Systematic index
Class DEMOSPONGIAE Sollas, Reference Sollas1885
Suborder HETEROSCLEROMORPHA Cárdenas, Perez & Boury-Esnault, Reference Cárdenas, Perez and Boury-Esnault2012
Order POLYMASTIIDA Morrow & Cárdenas, Reference Morrow and Cárdenas2015
Family POLYMASTIIDAE Gray, Reference Gray1867
Genus Polymastia Bowerbank, Reference Bowerbank1862
P. andrica de Laubenfels, Reference de Laubenfels1949
P. arctica (Merejkowsky, Reference Merejkowsky1878)
P. cf. bartletti de Laubenfels, Reference de Laubenfels1942
P. boletiformis (Lamarck, Reference Lamarck1815)
P. grimaldii (Topsent, Reference Topsent1913)
P. hemisphaerica (Sars, Reference Sars1872)
P. mamillaris (Müller, Reference Müller1806)
P. nivea (Hansen, Reference Hansen1885)
P. penicillus (Montagu, Reference Montagu1814)
P. svenseni sp. nov. P. thielei Koltun, Reference Koltun1964
P. uberrima (Schmidt, Reference Schmidt1870)
Polymastia sp.
Genus Quasillina Norman, Reference Norman1869
Q. brevis Bowerbank, Reference Bowerbank1866
Genus Sphaerotylus Topsent, Reference Topsent1898
S. borealis (Swarczewsky, Reference Swarczewsky1906)
S. capitatus (Vosmaer, Reference Vosmaer1885)
Genus Spinularia Gray, Reference Gray1867
S. njordi sp. nov.
S. sarsii (Ridley & Dendy, Reference Ridley and Dendy1886) comb. nov.
S. spinularia (Bowerbank, Reference Bowerbank1866)
Genus Tentorium Vosmaer, Reference Vosmaer and Bronn1887
T. semisuberites (Schmidt, Reference Schmidt1870)
Genus Weberella Vosmaer, Reference Vosmaer1885
W. bursa (Müller, Reference Müller1806)

Description of taxa

Family POLYMASTIIDAE Gray, Reference Gray1867

Genus Polymastia Bowerbank, Reference Bowerbank1862

Original description: Polymastia Bowerbank, Reference Bowerbank1862, p. 1104.

External morphology

Cushion-shaped sponges covering the substrate and occupying up to 6 cm² (Figure 2A). Surface strongly hispid, covered with sediment, with up to several tens of cylindrical or flattened, greyish or whitish papillae which are 1–12 mm long and 1–5 mm wide. In preserved sponges exhalant and inhalant papillae do not differ in size or shape.

Anatomy

Choanosome in alcohol yellowish or greyish, dense. Main choanosomal skeleton composed of radiating tracts (88–417 µm thick) of principal spicules crossing the cortex and forming a surface hispidation reinforced with exotyles (Figure 2B). Ascending tracts also form a framework of the papilla skeleton. Auxiliary choanosomal skeleton comprises free-scattered small spicules, being especially abundant in the subcortical area. Cortex in alcohol light-coloured, firm, not detachable. Cortical skeleton constituted by a superficial palisade (116–232 µm thick) of small spicules, a middle layer (40–272 µm thick) of collagen fibres with low density of spicules and an internal layer (56–170 µm thick) of tangentially arranged intermediary spicules (Figure 2C). Skeleton of the papilla walls composed of two layers only, the superficial palisade and the internal tangential layer. Single small and intermediary spicules reinforce the bulkheads separating aquiferous canals and vestibules in the papillae.

Spicules

(Measurements based on seven specimens, individual variation presented in Table 2)

Table 2. Individual variation of spicule dimensions of Polymastia andrica (given in μm as minimum–mean–maximum). Parameters: length, diameter of tyle, proximal diameter of shaft, maximum diameter of shaft, number of spicules measured (N).

Principal spicules – styles (in the Canadian sponges) or subtylostyles to styles (Norwegian sponges), usually straight, fusiform, with tyles (if present) slightly displaced along the shafts, occasionally polytylote. Length 613–1248–2132 µm, diameter of tyle (if present) 5.1–11.1–14.3 µm, proximal diameter of shaft 3.8–11.1–18.2 µm, maximum diameter of shaft 8.9–23.9–33.8 µm, N = 230.

Intermediary spicules – subtylostyles to styles, straight or gently bent, fusiform, occasionally with tyles slightly displaced along the shafts. Length 316–517–898 µm, diameter of tyle (if present) 6.4–9.9–15.6 µm, proximal diameter of shaft 5.1–9.1–14.3 µm, maximum diameter of shaft 7.6–13.2–26.0 µm, N = 229.

Small spicules – tylostyles, often gently bent in the proximal part, usually slender, occasionally stout. Length 100–176–286 µm, diameter of tyle 2.1–6.5–13 µm, proximal diameter of shaft 1.8–4.5–10.4 µm, maximum diameter of shaft 2.1–7.1–15.6 µm, N = 280.

Exotyles – filiform styles (Canadian sponges and individual ZMBN 98074 from Troms) or filiform subtylostyles with weakly developed, often slightly displaced tyles (other Norwegian sponges). Length 1314–2358–5500 µm, diameter of tyle (if present) 2.5–6.7–12.7 µm, proximal diameter of shaft 2.0–5.6–13 µm, maximum diameter of shaft 5.1–12.6–31.2 µm, N = 58.

Strongyles (registered only in individual CMNI1980-0436 from the Gulf of St. Lawrence) – straight, fusiform or slender, occasionally with one or two weakly developed tyles. Length 26–47–156 µm, proximal diameter of shaft 9.1–15.3–18.2 µm, maximal diameter of shaft 9.1–21–41.6 µm, N = 30.

Genetic data

CO1 sequences obtained from five individuals of Polymastia andrica are identical, but an intragenomic polymorphism was observed in 28S rDNA of one individual (Matrix M34256 in TreeBase). Polymastia andrica is closely related to P. arctica and P. grimaldii, sharing with them five synapomorphies in CO1 (Online resource 2, p. 1) and four synapomorphies in 28S rDNA (Online resource 3, p. 1), which distinguish these three species from all other polymastiids. 28S rDNA of P. andrica, P. arctica and P. grimaldii displays a high level of intraspecific and intragenomic polymorphism with some identical gene versions found in the individuals from different species (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b; Matrices M34250 and M34256 in TreeBase). On the contrary, the CO1 data are consistent. In this gene P. andrica and P. arctica share one synapomorphy distinguishing them from all other polymastiids, and, additionally P. andrica has one autapomorphy (Online resource 2, p. 1). Apart from this autapomorphy, P. andrica differs from P. arctica by eight base pairs (bps), from P. grimaldii by 12 bps and from the type species of Polymastia, P. mamillaris, by 32 bps in CO1 (Matrix M34248 in TreeBase).

External morphology

Cushion-shaped sponges covering the substrate and occupying up to 100 cm² (Figure 3A, B). Surface thickly or thinly hispid, usually covered with sediment, with up to several hundred papillae. In living sponges the colour of papillae and the areas of the surface free of sediment cream to yellowish. Most papillae inhalant, cylindrical in shape, 2–18 mm in length and 1–6 mm in diameter. Average density of the inhalant papillae 13 per 1 cm² of the surface. The inhalant papillae may bear at the summits threads with up to six buds arranged in line (Figure 3B). Exhalant papillae usually conical, 3–12 mm long, 3–7 mm wide at base and 1–5 mm wide at summit, with oscula about 0.5 mm in diameter. One sponge may have up to 19 exhalant papillae.

Anatomy

Choanosome in life orange, dense. Main choanosomal skeleton composed of radial, or longitudinal tracts (170–460 µm thick) of principal spicules branching in the subcortical area, crossing the cortex and forming a surface hispidation (Figure 3C). Ascending tracts also form a framework of the papilla skeleton. Auxiliary choanosomal skeleton comprises free-scattered bundles, each of two to five small spicules, being especially abundant in the subcortical area. Cortex in life cream-coloured, firm, not detachable. Cortical skeleton constituted by a superficial palisade (180–310 µm thick) of small spicules, a middle layer (90–180 µm thick) of collagen fibres with low density of spicules and an internal layer (160–250 µm thick) of tangentially arranged intermediary spicules (Figure 3D). Skeleton of the papilla walls composed of two layers only, the superficial palisade and the internal tangential layer. Single intermediary spicules reinforce the bulkheads separating aquiferous canals and vestibules in the papillae.

Spicules

(measurements based on 43 specimens)

Principal spicules – subtylostyles, straight, fusiform. Length 620–868–1100 µm, maximal diameter of shaft 8.8–14.3–20.0 µm, N = 500.

Intermediary spicules – subtylostyles, straight or gently bent, slender. Length 270–414–550 µm, diameter of shaft 5.0–9.5–17.5 µm, N = 500.

Small spicules – tylostyles, gently bent, fusiform. Length 120–161–215 µm, diameter of tyle 3.8–5.5–7.5 µm, maximal diameter of shaft 3.8–4.8–6.3 µm, N = 500.

Genetic data

CO1 sequences obtained from five individuals of Polymastia arctica are identical, but these individuals differ in 28S rDNA (Matrix M34250 in TreeBase) and, moreover, three of them exhibit a polymorphism in this gene (Matrix M34256 in TreeBase). By both genes P. arctica is closely related to P. andrica and P. grimaldii (see the synapomorphies in the Genetic data section for P. andrica above). 28S rDNA of these three species displays a high level of intraspecific and intragenomic polymorphism, while the CO1 data are consistent (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). In this gene P. arctica has two autapomorphies (Online resource 2, p. 1). Apart from them, P. arctica differs from P. andrica by 7 bps, from P. grimaldii by 11 bps and from the type species of Polymastia, P. mamillaris, by 28 bps in CO1 (Matrix M34248 in TreeBase).

External morphology

Cushion-shaped sponges covering the substrate. Surface smooth, free of sediment, with long papillae lacking visible oscula. Canadian sponge ~51 × 42 × 4 mm in size, with 45 cylindrical papillae, which are 14–44 mm long and 1–4 mm wide. In life the surface is brown and the papillae are yellowish (Figure 4A). In alcohol both the surface and the papillae have become whitish. Swedish sponge 12 × 9 × 0.7 mm in size, with one cylindrical papilla which is 12 mm long and 1.8 mm wide (Figure 4B). Surface and papilla are whitish in alcohol.

Anatomy

Choanosome in alcohol whitish, dense. In both sponges studied main choanosomal skeleton composed of tracts of principal spicules (Figure 4C). The tracts, 71–135 µm thick in the middle of the body, radiate towards the base and the cortex. Ascending tracts also form a framework of the papilla skeleton. Examination of the auxiliary choanosomal skeleton and the cortex in the Swedish individual was not possible because of its small size. In the Canadian sponge the auxiliary choanosomal skeleton comprises small and intermediary spicules, most free-scattered, some in bundles of three to seven. Cortex dense, but friable, not detachable. Cortical skeleton constituted by a superficial palisade (106–166 µm thick) of small spicules, which is overlapped with an inner layer (203–286 µm thick) of criss-cross intermediary spicules (Figure 4D).

Spicules

GNM 904:1 (Sweden):

Principal spicules – mainly styles, occasionally subtylostyles with weakly developed tyles, usually straight, fusiform. Length 568–752–905 µm, proximal diameter of shaft 2.5–10.2–12.7 µm, maximum diameter of shaft 6.4–14.1–16.5 µm, N = 30.

Intermediary spicules – subtylostyles to styles, usually gently curved, slightly fusiform. Length 246–391–503 µm, diameter of tyle (if present) 6.4–9.2–12.7 µm, proximal diameter of shaft 5.1–8.0–10.2 µm, maximum diameter of shaft 7.6–10.1–12.7 µm, N = 30.

Small spicules – tylostyles, usually gently curved, slender. Length 94–134–165 µm, diameter of tyle 3.8–5.2–7.6 µm, proximal diameter of shaft 2.0–3.6–5.1 µm, maximum diameter of shaft 2.5–4.0–5.1 µm, N = 30.

ZMBN 098111 (Canada):

Principal spicules – styles, usually straight, fusiform. Length 930–1162–1327 µm, proximal diameter of shaft 10.2–12.1–15.2 µm, maximum diameter of shaft 14.0–17.1–20.3 µm, N = 30.

Intermediary spicules – subtylostyles to styles, usually gently curved, slightly fusiform. Length 467–565–648 µm, diameter of tyle (if present) 8.9–10.2–12.7 µm, proximal diameter of shaft 7.6–8.4–10.2 µm, maximum diameter of shaft 10.2–11.8–15.2 µm, N = 30.

Small spicules – tylostyles, usually gently curved, slender. Length 127–161–192 µm, diameter of tyle 4.6–5.3–6.4 µm, proximal diameter of shaft 2.5–3.5–5.1 µm, maximum diameter of shaft 3.8–5–6.4 µm, N = 30.

Holotype USNM 22692 (according to de Laubenfels, Reference de Laubenfels1942):

Principal choanosomal spicules – tylostyles. Length 540–600 µm, diameter of shaft 9–12 µm.

Small choanosomal spicules – length 200 µm, diameter of shaft 4 µm.

Cortical spicules (de Laubenfels did not distinguish between small and intermediary cortical spicules) – tylostyles. Length 350–400 µm, diameter of shaft 6 µm.

Genetic data

The Canadian Polymastia bartletti and the Swedish Polymastia cf. bartletti are distinguished by two bps in CO1 (Matrix M34248 in TreeBase) and four bps in 28S rDNA (Matrix M34250 in TreeBase). At the same time these sponges share nine synapomorphies in CO1 (Online resource 2, p. 3) and two synapomorphies in 28S rDNA (Online resource 3, p. 3) distinguishing them from other polymastiids. Apart from these synapomorphies, both P. bartletti and P. cf. bartletti differ from morphologically similar P. nivea by 27 bps in CO1 (Matrix M34248 in TreeBase) and 60 bps in 28S rDNA (Matrix M34250 in TreeBase) and from the type species of Polymastia, P. mamillaris, by 61 bps in CO1 (Matrix M34248 in TreeBase) and 84 bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Sponges cushion-shaped, covering the substrate or massive (Figure 5A). The largest individuals may occupy up to 100 cm². Surface smooth, sometimes covered with sediment, with cylindrical or conical papillae. In living sponges both the surface and the papillae bright orange or yellow. Inhalant papillae 6–18 mm long and 2–5 mm wide. About 2–3 inhalant papillae per 1 cm² of the surface. Exhalant papillae 16–36 mm long and 3–6 mm wide, with well visible oscula at the summits. A sponge may bear 1–6 exhalant papillae.

Anatomy

Choanosome in life slightly darker than cortex, crumbly. Main choanosomal skeleton composed of tracts of principal spicules forming a reticulation or meanders (Figure 5B, C). Ascending tracts form a framework of the papilla skeleton. Auxiliary choanosomal skeleton comprises free-scattered principal spicules. Cortex leather-like, easily detachable. Cortical skeleton constituted by a superficial palisade (80–250 µm thick) of small spicules and an internal layer (169–420 µm thick) of criss-cross principal spicules (Figure 5C). Aquiferous cavities connected with ostia in the surface and separated by bundles of intermediary spicules lie in a space (125–400 µm thick) between the cortex and the choanosome. Both cortical layers extend to the walls of papillae. Each papilla bears several inhalant canals, and in exhalant papilla there are also one to three exhalant canals located midmost. Bulkheads separating the canals are reinforced with free-scattered principal spicules.

Spicules

(Measurements based on four specimens)

Principal spicules – subtylostyles, straight or gently curved, slender or slightly fusiform. Length 261–540–735 µm, proximal diameter of shaft 5.1–6.7–9.0 µm, maximum diameter of shaft 7.5–10.4–12.7 µm, N = 120.

Small spicules – subtylostyles with weakly developed tyles, usually gently bent in the proximal part, slender. Length 91–153–232 µm, proximal diameter 2.0–3.1–3.9 µm, maximum diameter of shaft 2.0–3.2–3.9 µm, N = 124.

Genetic data

In both CO1 and 28S rDNA phylogenies Polymastia boletiformis is the sister to morphologically quite distinct Quasillina brevis (Bowerbank, Reference Bowerbank1866) (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). These species share three synapomorphies in CO1 (Online resource 2, p. 4) and 24 synapomorphies in 28S rDNA (Online resource 3, p. 4). CO1 data were obtained from two specimens of P. boletiformis, of which one differs from Q. brevis just by one bp in this gene, while the other differs from Q. brevis by six bps (Matrix M34248 in TreeBase). 28S rDNA sequences obtained from six Scandinavian P. boletiformis are identical to the sequences of a British P. boletiformis (GenBank accessions HQ379232, HQ379306 and HQ379372, Morrow et al., Reference Morrow, Picton, Erpenbeck, Boury-Esnault, Maggs and Allcock2012) and display six synapomorphies distinguishing them from all other polymastiids (Online resource 3, p. 4). Apart from these synapomorphies, P. boletiformis differs from Q. brevis by 17 bps in 28S rDNA (Matrix M34250 in TreeBase) and from the type species of Polymastia, P. mamillaris by 64–67 bps in CO1 (considering the intraspecific polymorphism, Matrix M34248) and 89 bps in 28S rDNA (Matrix M34250).

External morphology

Lectotype with almost circular, flat upper surface, 40–41 mm in diameter, and convex basal surface with a central point 22 mm distant from the upper surface (Figure 6A–C). Upper surface strongly hispid, greyish, with a single central exhalant papilla, cylindrical in shape, 9 mm long and 4 mm in diameter, and 118 inhalant papillae, most flattened, slightly widened towards the top, 1–6 mm in length and 0.7–2 mm in diameter at base (Figure 6A). Basal surface sleek, beige to grey, damaged in a central point indicating that the sponge was attached to a tiny substrate (Figure 6C). A fringe of extra-long spicules, 1.5 mm wide, developed at the sponge edge between the upper and basal surface (Figure 6B). Other sponges discoid, hemispherical with either the upper or the basal surface being convex, or sometimes lenticular. Upper surface up to 200 cm², strongly hispid, usually covered with sediment, with up to 300 papillae, of which most are inhalant and one to six are exhalant, with well-visible oscula. The exhalant papillae cylindrical or conical, up to 16 mm in length. The inhalant papillae flattened, leaf-shaped, or sometimes cylindrical, up to 9 mm in length. Basal surface smooth, sometimes even sleek, attached to a small substrate only by a central point. Marginal fringe of extra-long spicules preventing sinking of the sponge into the sediment may be reduced in some individuals.

Anatomy

Choanosome in life pale orange or beige, firm (Figure 6G). Main choanosomal skeleton composed of tracts (65–655 µm thick) of principal spicules radiating from sponge base and dividing into two to four thinner tracts, which cross the upper cortex and form a surface hispidation (Figure 6G, H). Ascending tracts also form a framework of the papilla skeleton. Auxiliary choanosomal skeleton comprises free-scattered small spicules, especially concentrating below the upper cortex. Cortex in life whitish, firm, not detachable (Figure 6G). Skeleton of the upper cortex constituted by a superficial palisade (170–210 µm thick) of small spicules, a middle layer (100–180 µm thick) of collagen fibres with low density of spicules and an internal layer (100–140 µm thick) of tangentially arranged intermediary spicules (Figure 6I). Skeleton of the basal cortex (520–700 µm thick) formed by the peripheral tracts of principal spicules running parallel to the surface overlapped by a superficial palisade of small spicules and an inner confused mass of intermediary spicules (Figure 6J). Marginal fringe composed of bundles of extra-long spicules (exotyles) embedded into the cortex. Skeleton of the papilla walls composed of the superficial palisade and the internal tangential layer. Both inhalant and exhalant papillae with single central canals.

Spicules

(measurements based on 15 specimens)

Principal spicules – strongyloxeas, straight or gently curved. Length 1450–2358–3235, maximum diameter of shaft 21.0–24.8–29.2 µm, N = 450.

Intermediary spicules – tylostyles, straight or gently bent, fusiform. Length 212–445–671 µm, maximum diameter of shaft 15.8–18.4–24.0 µm, N = 450.

Small spicules – tylostyles to subtylostyles, straight or gently bent, usually slender. Length 147–228–287 µm, maximum diameter of shaft 3.8–6.4–7.8 µm, N = 450.

Exotyles (spicules of the marginal fringe) – flexuous styles, occasionally subtylostyles. Length 2020–4527–7000 µm, maximum diameter 8.0–9.4–10.6 µm, N = 150.

Genetic data

CO1 sequences obtained from three individuals of Polymastia grimaldii are identical. 28S rDNA available only from one of these individuals is polymorphic (Matrix M34256 in TreeBase). By both genes P. grimaldii is closely related to P. andrica and P. arctica (see the synapomorphies in the Genetic data section for P. andrica above). 28S rDNA of these three species displays intraspecific and intragenomic polymorphism, while the CO1 data are consistent (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). In CO1 P. grimaldii has one autapomorphy (Online resource 2, p. 1). Apart from the latter, this species differs from P. andrica by 12 bps, from P. arctica by 12 bps and from the type species of Polymastia, P. mamillaris, by 31 bps in CO1 (Matrix M34248 in TreeBase).

External morphology

Holotype hemispherical, 80–86 mm in diameter. Upper surface convex, knobbly, cream-coloured, with 18 papillae (Figure 8A). Papillae conical, 1–5 mm long and 1.5–3.5 mm wide at base, with considerably contracted oscula at the summits. Basal surface shaggy, pale grey in colour, attached to a bivalve shell by the central point (Figure 8B). A fringe of extra-long spicules, 4–9 mm wide, developed at the sponge edge separating the upper and basal surface. Other sponges hemispherical or discoid, up to 65 mm in diameter, with the marginal spicule fringe up to 13 mm in width. Upper surface whitish or cream-coloured in life, knobbly, with up to 30 conical papillae. In living sponges the papillae with well visible oscula. Under sampling and preservation the papillae stretch and the oscula contract. Basal surface shaggy or hispid, attached to a small substrate.

Anatomy

Choanosome in life yellowish or pale orange, firm. Main choanosomal skeleton composed of tracts (190–416 µm thick) of principal spicules radiating from the basal area and entering the cortex (Figure 8C). In the upper cortex the tracts run perpendicular to the surface and do not protrude. Some tracts ascend to the papillae. In the basal cortex the tracts run obliquely to the surface and stick out forming a thick hispidation. Auxiliary choanosomal skeleton comprises free-scattered small spicules and bundles of intermediary spicules concentrated in the subcortical area. Cortex in life whitish, firm, not detachable. Cortical skeleton constituted by a notched superficial palisade (366–522 µm thick) of small spicules and an internal layer (663–930 µm thick in the upper cortex and up to 1280 µm thick at the basal central point) of criss-cross intermediary spicules (Figure 8C, D). Marginal fringe composed of bundles of extra-long spicules (exotyles) embedded into the cortex. In the upper part of the body the cortex and the choanosome separated by an area with low concentration of spicules (127–206 µm thick). Papilla walls reinforced with the cortical palisade. Each papilla with a central exhalant canal and several peripheral inhalant canals.

Spicules

(Measurements based on 10 specimens)

Principal spicules – styles to subtylostyles, straight or gently curved, slightly fusiform. Length 1920–3125–5400, maximum diameter of shaft 10.9–20.2–32.3 µm, N = 200.

Intermediary spicules – tylostyles, straight, fusiform. Length 390–512–618 µm, maximum diameter of shaft 17.2–19.9–26.2 µm, N = 300.

Small spicules – tylostyles, usually gently bent in the distal part, slender. Length 160–229–305 µm, maximum diameter of shaft 4.2–5.8–8.4 µm, N = 300.

Exotyles (spicules of the marginal fringe) – styles, straight, slightly fusiform. Length 4990–6511–8015 µm, maximum diameter 45.8–47.5–50.1 µm, N = 100.

Genetic data

CO1 was obtained from six individuals of Polymastia hemisphaerica, while 28S rDNA were sequenced only from three of them. By both genes P. hemisphaerica is closely related to morphologically quite different P. thielei (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). These species share two synapomorphies in CO1 (Online resource 2, p. 2) and two synapomorphies in 28S rDNA (Online resource 3, p. 2) and, apart from them, differ from the type species of Polymastia, P. mamillaris, by 18 bps in CO1 (Matrix M34248 in TreeBase) and six bps in 28S rDNA (Matrix M34250 in TreeBase). At the same time P. hemisphaerica demonstrates an intraspecific polymorphism. In CO1 five individuals of this species differ from P. thielei just by one bp, while one individual, ZMBN 098056, differs from P. thielei by two bps (Matrix M34248 in TreeBase). On the contrary, by 28S rDNA ZMBN 098056 is identical to two other conspecific sponges differing from P. thielei just by one insertion in this gene, while another individual of P. hemisphaerica, ZMBN 098043 possessing the same insertion, is distinguished from both the conspecific individuals and P. thielei by three bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Cushion-shaped sponges covering the substrate and occupying up to 9 cm². Surface hispid, usually covered with sediment, with up to 30 papillae, 5–12 mm long and 2–5 mm wide at base (Figure 10A, B). In living sponges the papillae tapering towards the summits, some with visible oscula (Figure 10B). Colour of papillae whitish in life and cream-coloured in alcohol.

Anatomy

Choanosome in life cream-coloured, firm. Main choanosomal skeleton of radiating tracts (240–370 µm thick) of principal spicules dividing into two to three thinner tracts, which cross the cortex and form a surface hispidation (Figure 10C). Ascending tracts also form a framework of the papilla skeleton. Auxiliary choanosomal skeleton comprises free-scattered bundles, each of two to five small spicules, being especially abundant in the subcortical area. Cortex in life whitish, firm, not detachable. Cortical skeleton constituted by a superficial palisade (120–150 µm thick) of small spicules, a middle layer (65–105 µm thick) of collagen fibres with low density of spicules and an internal layer (85–155 µm thick) of tangentially arranged intermediary spicules (Figure 10D). Skeleton of the papilla walls composed of two layers only, the superficial palisade and the internal tangential layer.

Spicules

(Measurements based on three specimens, individual variation presented in Table 3)

Table 3. Individual variation of spicule dimensions of Polymastia mamillaris (given in μm as minimum–mean–maximum). Parameters: length, diameter of tyle, proximal diameter of shaft, maximum diameter of shaft, number of spicules measured (N).

Principal spicules – straight strongyloxeas or straight, fusiform styles to subtylostyles. Length 603–1075–1761 µm, diameter of tyle (if present) 5.6–9.8–15.2 µm, proximal diameter of shaft 2.5–8.3–12.7 µm, maximum diameter of shaft 7.6–18.0–29.2 µm, N = 90.

Intermediary spicules – styles, occasionally subtylostyles, usually straight, slightly fusiform. Length 241–422–538 µm, diameter of tyle (if present) 5.1–7.4–10.2 µm, proximal diameter of shaft 2.5–6.1–8.9 µm, maximum diameter of shaft 6.4–8.9–14.0 µm, N = 90.

Small spicules – tylostyles, gently curved or straight, stout. Length 94–148–206 µm, diameter of tyle 3.8–6.0–10.2 µm, proximal diameter of shaft 1.3–3.8–8.9 µm, maximum diameter of shaft 2.5–6.3–11.4 µm, N = 90.

Genetic data

CO1 sequences obtained from two individuals of Polymastia mamillaris are identical (Matrix M34248 in TreeBase), but these sponges are distinguished by one bp in 28S rDNA (Matrix M34250 in TreeBase). Polymastia mamillaris differs from all other polymastiids by five autapomorphies in CO1 (Online resource 2, p. 1) and one autapomorphy in 28S rDNA (Online resource 3, p. 1). More details on the differences between P. mamillaris and other Polymastia spp. are presented in the Genetic data sections for these species.

External morphology

All type specimens of Reniera nivea cream-coloured in alcohol, with smooth surface bearing damaged cylindrical papillae (Figure 11A–C). Lectotype ~30 × 17 × 6 mm, with 19 papillae (Figure 11A). Larger paralectotype 24 × 18 × 5 mm, with 20 papillae (Figure 11B). Smaller lectotype is a small sponge fragment with five papillae (Figure 11C). Holotype of Polymastia euplectella ~30 × 12 × 5 mm (Figure 11D). Surface smooth, with 18 papillae, 10–40 mm long and 3–7 mm wide at base, gently pointed at the summits. Colour of both the surface and papillae whitish in alcohol. Papilla walls display a conspicuous tracery network of spicules.

Other sponges cushion-shaped, covering the substrate and occupying up to 20 cm². Surface smooth, free of sediment, with up to 30 papillae (Figure 11E, F). Colour of the surface in life pale orange or pale yellow, sometimes whitish, in alcohol always becoming whitish. Papillae of most living individuals cylindrical, 8–60 mm in length and 2–8 mm in diameter, semitransparent with well-visible spicule network, oscula not visible (Figure 11E). Some sponges with much smaller (2–6 mm in length and 1–4 mm in diameter) papillae of the same colouration as the surface (Figure 11F).

Anatomy

Choanosome dense. Main choanosomal skeleton composed of longitudinal or radial tracts (110–310 µm thick) of principal spicules (Figure 11G). Auxiliary choanosomal skeleton comprises small and intermediary spicules, most free-scattered, some in bundles of three to seven. Cortex 275–460 µm thick, dense, but friable, not detachable, with small aquiferous cavities connected with ostia in the surface. Cortical skeleton constituted by a superficial palisade of small spicules, which is overlapped with an inner layer of criss-cross intermediary spicules (Figure 11G). Papilla with a single central canal enveloped by a network made of the tracts of principal spicules ascending from the choanosome crossed by bundles of intermediary spicules from the outside. Superficial layer of small spicules covers this network.

Spicules

(Measurements based on four specimens, individual variation presented in Table 4)

Table 4. Individual variation of spicule dimensions of Polymastia nivea (given in μm as minimum–mean–maximum). Parameters: length, diameter of tyle, proximal diameter of shaft, maximum diameter of shaft, number of spicules measured (N).

Principal spicules – strongyloxeas (ZMBN 000055), slender styles to subtylostyles (ZIN RAS 07102/07103, ZMBN 098044), or fusiform subtylostyles with displaced tyles (ZMBN 098085), usually straight, occasionally gently curved. Length 573–1194–1686 µm, diameter of tyle (if present) 8.9–10.2–11.4 µm, proximal diameter of shaft 2.5–9.6–15.2 µm, maximum diameter of shaft 8.9–17.4–25.4 µm, N = 120.

Intermediary spicules – gently curved tylostyles, usually stout or slightly fusiform (most sponges), occasionally slenderer (ZMBN 098085). Length 271–434–771 µm, diameter of tyle (if present) 5.1–11.9–18.2 µm, proximal diameter of shaft 3.8–8.4–12.7 µm, maximum diameter of shaft 7.6–14.7–21.6 µm, N = 120.

Small spicules – subtylostyles with weakly developed tyles, usually curved and slender. Length 114–164–231 µm, diameter of tyle 3.8–5.2–7.6 µm, proximal diameter of shaft 2.0–3.5–5.1 µm, maximum diameter of shaft 2.5–4.8–7.6 µm, N = 120.

Genetic data

CO1 was obtained from four individuals of Polymastia nivea, 28S rDNA was sequenced from three of them and no intraspecific polymorphism was revealed. In the phylogenies based on these genes P. nivea is closely related to P. penicillus (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b), although these species share just two synapomorphies in 28S rDNA distinguishing them from other polymastiids (Online resource 3, p. 3) and no such synapomorphies in CO1. At the same time P. nivea possesses one autapomorphy in CO1 (Online resource 2, p. 3) and four autapomorphies in 28S rDNA (Online resource 3, p. 3). Apart from these autapomorphies, P. nivea differs from P. penicillus by 6 bps in CO1 (Matrix M34248 in TreeBase) and 19 bps in 28S rDNA (Matrix M34250 in TreeBase) and from the type species of Polymastia, P. mamillaris, by 56 bps in CO1 (Matrix M34248 in TreeBase) and 85 bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Cushion-shaped sponges up to 10 mm thick, covering the substrate and occupying up to 300 cm² (Figure 13A, B). Surface velvety rather than hispid, with up to 200 papillae, of which several (one to five depending on sponge size) with visible oscula at the summits. In life the surface dirty grey to yellow or pale orange. The papillae cream-coloured to pale yellow, up to 12 mm in length and 5 mm in diameter, cylindrical or gently tapering towards the summits (Figure 13A). Under sampling the papillae contract and the oscula close (Figure 13B). Sponges usually buried in sediment with only the papillae protruding outwards.

Anatomy

Choanosome in alcohol firm, cream-coloured. Main choanosomal skeleton composed of longitudinal or radial tracts (125–360 µm thick) of principal spicules fanning under the cortex, crossing the cortex and forming a fine surface hispidation (Figure 13C). Auxiliary choanosomal skeleton comprises free-scattered intermediary spicules. Cortex in alcohol whitish, firm, not detachable. Cortical skeleton constituted by a superficial palisade (110–140 µm thick) of small spicules and an internal layer (350–500 µm thick) of tangentially arranged intermediary spicules (Figure 13C). Skeleton of the papilla walls is a framework of the tracts ascending from the choanosome and covered with the cortical layers.

Spicules

(Measurements based on four specimens)

Principal spicules – tylostyles (holotype and the Irish individual) or styles to subtylostyles with weakly developed, displaced tyles (Swedish sponges), usually straight and fusiform. Length 603–959–1490 µm, proximal diameter of shaft 2.5–8.3–12.7 µm, maximum diameter of shaft 7.6–12.3–20.3 µm, N = 120.

Intermediary spicules – tylostyles, occasionally subtylostyles with weakly developed tyles, gently curved or straight, usually slender, occasionally fusiform. Length 300–478–710 µm, diameter of tyle 5.1–8.0–10.2 µm, proximal diameter of shaft 2.5–6.4–8.9 µm, maximum diameter of shaft 5.1–10.0–15.2 µm, N = 120.

Small spicules – tylostyles, gently curved, slender or slightly fusiform. Length 79–155–201 µm, diameter of tyle 3.8–4.7–6.4 µm, proximal diameter of shaft 1.5–3.0–5.1 µm, maximum diameter of shaft 1.5–3.3–6.4 µm, N = 120.

Genetic data

28S rDNA sequences obtained from three individuals of Polymastia penicillus, two from Sweden and one from Northern Ireland, are identical. CO1 was obtained only from the Irish sponge, and this sequence is identical to the CO1 sequence from a Portuguese P. penicillus (GenBank accessions KF225486 and KF225487, Alex et al., Reference Alex, Silva, Vasconcelos and Antunes2013). In both 28S rDNA and CO1 phylogenies P. penicillus is related to P. nivea (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b), although these species share just two synapomorphies and display many differences (for details see the Genetic data section for P. nivea above). Polymastia penicillus is distinguished from all other polymastiids by two autapomorphies in 28S rDNA (Online resource 3, p. 3). Apart from them, P. penicillus differs from the type species of Polymastia, P. mamillaris, by 51 bps in CO1 (Matrix M34248 in TreeBase) and 82 bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Both holotype and paratype cushion-shaped, removed from a rock cliff. Surface, for the most part, smooth, cream-coloured in alcohol, with sparse rests of sediment and papillae, which may be conical tapering towards the summits, cylindrical or leaf-shaped expanding towards the summits. Holotype 105 × 52 × 13 mm, with 157 papillae 2–13 mm long and 1.5–5.5 mm (Figure 14A). Paratype 67 × 44 × 12 mm, with 76 papillae 2–15 mm long and 1.4–6.7 mm wide. Other sponges cushion-shaped, occupying up to 250 cm² of the substrate (Figure 14B). Surface cream-coloured or whitish in life, smooth, partly covered with sediment, with up to 400 papillae tapering towards the summits. Few papillae with visible oscula at the summits.

Anatomy

Choanosome in life pale orange or yellowish, firm. Main choanosomal skeleton composed of tracts (112–321 µm thick) of large spicules radiating from the base and ending in the cortex (Figure 14C). Ascending tracts also form a framework of the papilla skeleton. Auxiliary choanosomal skeleton comprises free-scattered large and small spicules. Cortex in life whitish, firm, not detachable. Cortical skeleton constituted by a superficial palisade (220–240 µm thick) of small spicules, a middle layer (130–150 µm thick) and an internal layer (100–125 µm thick), both composed of criss-cross large spicules lying loosely in the middle layer and much more condensed in the internal layer (Figure 14C). Skeleton of the papilla walls composed of two cortical layers, the superficial palisade and the internal layer.

Spicules

(Measurements based on three specimens, individual variation presented in Table 5)

Table 5. Individual variation of spicule dimensions of Polymastia svenseni (given in μm as minimum–mean–maximum). Parameters: length, diameter of tyle, proximal diameter of shaft, maximum diameter of shaft, number of spicules measured (N).

Large spicules – mainly styles (Figure 14D–F), occasionally subtylostyles with weakly developed and displaced tyles (Figure 14G–I), usually straight, sometimes gently curved, fusiform to a greater or lesser extent. Length 312–658–1364 µm, diameter of tyle (if present) 3.0–7.8–14.0 µm, proximal diameter of shaft 2.5–6.8–11.4 µm, maximum diameter of shaft 3.8–10.9–16.5 µm, N = 187. The large spicules vary greatly in size, both in the cortex and choanosome, but the frequency distribution of their dimensions exhibits just one peak and hence they cannot be divided into two size categories.

Small spicules – tylostyles, usually gently curved, slender (Figure 14J–O). Length 132–175–225 µm, diameter of tyle 3.6–4.7–5.1 µm, proximal diameter of shaft 2.0–2.8–3.8 µm, maximum diameter of shaft 2.5–3.7–5.1 µm, N = 90.

Genetic data

CO1 and 28S rDNA obtained from two individuals of Polymastia svenseni display no intraspecific polymorphism. B10–C1 region of 28S rDNA sequenced by Morrow et al. (Reference Morrow, Picton, Erpenbeck, Boury-Esnault, Maggs and Allcock2012) from an unidentified Irish Polymastia sp. (GenBank accession KF017187) is identical to the corresponding gene fragment of P. svenseni (about 1/3 length of our sequences). By both CO1 and 28S rDNA P. svenseni is closely related to a Norwegian Polymastia sp. described below, and by CO1 alone these two are closely related to an unidentified Canadian Polymastia (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b), for which no 28S rDNA is available and which is not covered by the present study. These sponges share nine synapomorphies in CO1 (Online resource 2, p. 3, Matrix M34248 in TreeBase). Polymastia svenseni and the Norwegian Polymastia sp. also share two synapomorphies in 28S rDNA distinguishing these taxa from all other polymastiids (Online resource 3, p. 3). At the same time P. svenseni is distinguished by two autapomorphies in 28S rDNA (Online resource 3, p. 3). Apart from these autapomorphies, it differs from the Norwegian Polymastia sp. by 21 bps in CO1 (Matrix M34248 in TreeBase), from the Canadian Polymastia sp. by 17 bps in CO1 (Matrix M34248 in TreeBase), and from the type species of Polymastia, P. mamillaris, by 65 bps in CO1 (Matrix M34248 in TreeBase) and 21 bps in 28S rDNA (Matrix M34250 in TreeBase). In the CO1 phylogeny the trio Polymastia svenseni + Norwegian Polymastia sp. + Canadian Polymastia sp. is the sister to the clade of seven other Polymastia spp. including P. mamillaris, although with a weak Bayesian support (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). In the 28S rDNA phylogeny the pair Polymastia svenseni + Norwegian Polymastia sp. is the sister to the same clade with a high support (the same study).

External morphology

Lectotype globular, about 50 mm in diameter, attached to small stones (Figure 15A). Surface velvety, pale beige with sparsely scattered small brown stains, bearing 18 papillae. The papillae crater-shaped (very short and wide) or conical, 1.5–5.5 mm long and 1.7–9.2 mm wide at base, most with well-visible oscula at the summits. Paratype ZIN RAS 10638 irregularly ovoid, 81 × 60 mm in diameter, split across, removed from the substrate (Figure 15B). Surface velvety, pale brown with darker stains, bearing 23 wart-like small papillae, the largest with oscula at the summits. Paratypes ZIN RAS 10639 are small, massive sponges on stones or removed from the substrates (Figure 15C–H). Surface, for the most part, velvety or knobbly, porous in some individuals, brownish, with one or few conical or crater-shaped papillae, all with oscula at the summits. Some paratypes with minute hispidation around the base. Other sponges massive, fist-shaped, globular or ovoid, up to 250 mm in diameter (Figure 15I). Surface knobbly, velvety or smooth, with well-visible ostia. Colour in life whitish, cream-coloured or beige, occasionally with large dark brown spots. In alcohol the colouration darkens and the ostia contract. Up to 30 papillae, all with oscula at the summits, crater-shaped in life and often stretching under sampling.

Anatomy

Choanosome pale brown to dark brown, both in life and in alcohol, somewhat loose, porous, with prominent meandering and anastomosing exhalant canals (up to 8 mm in diameter) running to the papillae. Main choanosomal skeleton composed of tracts (90–360 µm thick) of principal spicules radiating from the sponge base (Figure 15J). In the central part of the choanosome the tracts often meander and ramify, sometimes anastomose and form a network. Auxiliary choanosomal skeleton comprises small spicules, free-scattered or grouped in little bundles, especially abundant in a subcortical area (200–350 µm thick). Within the choanosome the walls of the exhalant canals paved with criss-cross small and intermediary spicules. Cortex in life cream-coloured, dense, but detachable. Cortical skeleton includes a superficial layer (340–650 µm thick) formed by bouquets of small spicules and an internal layer (150–250 µm thick) of criss-cross intermediary spicules (Figure 15K). A space (650–880 µm thick) between the spicule layers is occupied by oval aquiferous cavities (190–480 × 70–240 µm in diameter) connected with ostia which are located between the superficial spicule bouquets. Bulkheads between the aquiferous cavities reinforced with the ascending choanosomal tracts and criss-cross intermediary spicules. The papillae walls reinforced with the ascending choanosomal tracts and covered with the spicule cortical layers.

Spicules

(Measurements based on 10 specimens)

Principal spicules – styles to subtylostyles, usually straight and fusiform. Length 693–1277–1705 µm, proximal diameter of shaft 5.0–9.8–14.2 µm, maximum diameter of shaft 12.5–18.4–25.1 µm, N = 300.

Intermediary spicules – subtylostyles to tylostyles, straight or gently curved, fusiform. Length 445–539–648 µm, diameter of tyle 4.2–7.0–8.2 µm, proximal diameter of shaft 3.2–5.8–7.1 µm, maximum diameter of shaft 10.5–11.2–12.3 µm, N = 300.

Small spicules – tylostyles, gently curved, slender or slightly fusiform. Length 219–297–363 µm, diameter of tyle 3.8–5.5–7.4 µm, proximal diameter of shaft 1.7–3.8–5.7 µm, maximum diameter of shaft 4.1–6.8–9.3 µm, N = 300.

Genetic data

CO1 sequences obtained from five individuals of Polymastia thielei are identical. 28S rDNA was obtained only from one of these sponges. By both genes P. thielei is closely related to morphologically quite different P. hemisphaerica (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). The synapomorphies and differences between these species are described above in the Genetic data section for P. hemisphaerica.

External morphology

Holotype of Rinalda uberrima massive, ~46 × 27 × 29 mm, removed from the substrate (Figure 17A). Surface, for the most part, smooth, cream-coloured, with about 20 papillae and a minutely hispid greyish edging, 5–6 mm wide, on the undamaged side. Most papillae wart-like, weakly developed, but some conical, up to 5 mm long and 7 mm wide at base, with visible oscula at the summits. Lectotype and paralectotypes of Polymastia infrapilosa massive, removed from the substrates. Surface, for the most part, smooth, cream-coloured, with a minute hispidation, 6–7 mm wide, along the undamaged edge and conical, occasionally cylindrical, papillae bearing oscula at the summits. Lectotype ~42 × 38 × 21 mm, split across, with 49 papillae, which are 2–12 mm long, 2–8 mm wide at base and 1–2 mm wide at summit (Figure 17B, C). Paralectotypes ~36 × 30 × 16 mm, with 23 papillae, and 37 × 29.5 × 10 mm, with 30 papillae. The latter with several surface protuberances, each bearing one to three buds, 2–3 mm in diameter. Other sponges massive or globular, occupying up to 100 mm² of the substrate. Except for a marginal collar, the surface smooth or velvety, whitish in life, but often darkening in alcohol, with up to 150 conical or cylindrical papillae, in life all with visible oscula. The marginal collar is a rough, hispid or even shaggy area of various widths (Figure 17D).

Anatomy

Choanosome yellowish in life, but may become dark brown in alcohol, dense. Main choanosomal skeleton composed of tracts (207–571 µm thick) of principal spicules radiating from the sponge base and occasionally ramifying under the cortex (Figure 17E, F). Most tracts end in the cortex except for the marginal area where they protrude above the surface. Some tracts ascend to the papillae (Figure 17F). Auxiliary choanosomal skeleton comprises small bundles of intermediary spicules, especially abundant in a subcortical area (423–1484 µm thick). Cortex in life cream-coloured, firm, not detachable. Cortical skeleton includes a superficial palisade (201–257 µm thick) of small spicules, a middle layer of loosely and confusedly lying bundles of intermediary spicules (672–1437 µm thick) and an internal layer (181–326 µm thick) with a high concentration of criss-cross intermediary spicules. In the areas under the papillae the middle layer contains aquiferous cavities connected with the surface ostia (Figure 17F). The papillae walls reinforced with the ascending choanosomal tracts and covered with the superficial palisade and internal cortical layer. Several exhalant and inhalant canals running into the papillae are separated by bulkheads reinforced with the ascending tracts and free-scattered intermediary spicules.

Spicules

(Measurements based on nine specimens, individual variation presented in Table 6)

Table 6. Individual variation of spicule dimensions of Polymastia uberrima (given in μm as minimum–mean–maximum). Parameters: length, proximal diameter of shaft, maximum diameter of shaft, number of spicules measured (N).

Principal spicules – styles to subtylostyles, straight, fusiform. Length 715–1409–1889 µm, proximal diameter of shaft 7.9–13.1–17.2 µm, maximum diameter of shaft 10.7–23.1–30.4 µm, N = 270.

Intermediary spicules – styles to subtylostyles, occasionally tylostyles, straight or occasionally gently curved, fusiform. Length 381–550–706 µm, proximal diameter of shaft 5.8–8.5–12.5 µm, maximum diameter of shaft 7.2–11.8–16.5 µm, N = 270.

Small spicules – subtylostyles to tylostyles, gently curved or straight, fusiform. Length 153–218–327 µm, proximal diameter of shaft 2.2–3.1–4.5 µm, maximum diameter of shaft 3.3–6.4–8.9 µm, N = 270.

Genetic data

CO1 sequences obtained from two individuals of Polymastia uberrima are identical, but these sponges differ by one bp in 28S rDNA (Matrix M34250 in TreeBase). In both CO1 and 28S rDNA phylogenies P. uberrima falls in the clade with six other Polymastia spp. including the type species of this genus, P. mamillaris (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). However, P. uberrima does not have sister relation to any of these species. It is distinguished by two autapomorphies in CO1 (Online resource 2, p. 2) and three autapomorphies in 28S rDNA (Online resource 3, p. 2) from all other polymastiids. Apart from these autapomorphies, P. uberrima differs from P. mamillaris by 31 bps in CO1 (Matrix M34248 in TreeBase) and 15 bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Encrusting sponge, about 12 mm in diameter and 5 mm thick, removed from the substrate (Figure 19A). Surface strongly hispid, covered with sediment, bearing a conical papilla, 16.5 mm long and 4.6 mm wide at base, with a small osculum at the summit.

Anatomy

Choanosome in alcohol pale orange, firm. Main choanosomal skeleton composed of radiating tracts (92–106 µm thick) of principal spicules crossing the cortex and forming a surface hispidation reinforced with exotyles (Figure 19B). Auxiliary choanosomal skeleton comprises bundles of free-scattered small spicules. Cortex in alcohol light-coloured, firm, not detachable. Cortical skeleton constituted by a superficial palisade (170–200 µm thick) of small spicules and an internal layer (139–184 µm thick) of criss-cross intermediary spicules (Figure 19B).

Spicules

Principal spicules – subtylostyles with slightly displaced tyles, occasionally polytylote, straight, fusiform. Length 880–1257–2034 µm, diameter of tyle 8.1–12.2–17.8 µm, proximal diameter of shaft 6.4–9.7–11.4 µm, maximum diameter 12.7–16.8–20.3 µm, N = 30.

Intermediary spicules – subtylostyles, straight, slender. Length 442–557–693 µm, diameter of tyle 7.6–8.7–10.2 µm, proximal diameter of shaft 5.1–6.7–8.9 µm, maximum diameter 7.6–10.0–11.4 µm, N = 30.

Small spicules – tylostyles, often bent in the proximal part, stout. Length 132–162–183 µm, diameter of tyle 3.8–5.6–7.6 µm, proximal diameter of shaft 2.5–3.7–5.1 µm, maximum diameter of shaft 2.5–5.0–6.4 µm, N = 30.

Exotyles – filiform subtylostyles. Length 1860–2590–3770 µm, diameter of tyle 12.7–14.1–16.5 µm, proximal diameter of shaft 7.6–10.9–14.0 µm, maximum diameter of shaft 10.2–13.8–17.8 µm, N = 10.

Genetic data

The Norwegian Polymastia sp. described above is genetically very close to P. svenseni and an unidentified Canadian Polymastia (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). The relationships of this trio with other polymastiids and the synapomorphies between the Norwegian Polymastia sp. and P. svenseni are described in the Genetic data section for the latter species above. Three synapomorphies in CO1 distinguish the Norwegian Polymastia sp. and the Canadian Polymastia sp. from all other polymastiids (Online resource 2, p. 3, Matrix M34248 in TreeBase). At the same time the Norwegian Polymastia sp. is distinguished by two autapomorphies in this gene (Online resource 2, p. 3). Apart from them, it differs from the Canadian Polymastia sp. by four bps in CO1 (Matrix M34248 in TreeBase), from P. svenseni by 19 bps in CO1 (Matrix M34248 in TreeBase) and two bps in 28S rDNA (Matrix M34250 in TreeBase) and from the type species of Polymastia, P. mamillaris, by 68 bps in CO1 (Matrix M34248 in TreeBase) and 21 bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Lectotype of Polymastia brevis has an irregularly ovoid main body, ~25 mm in diameter and 28 mm high, sitting on a stalk, ~11 mm high and 7 mm in diameter and bearing a well developed cylindrical papilla, ~5 mm long and 3 mm in diameter, with an osculum at the summit (Figure 21A). Paralectotypes smaller, some with weakly developed papillae, others lacking papillae and bearing oscula directly on the body summits. Most other sponges columnar, up to 35 mm high and up to 8 mm in diameter, with no segregation between main body and stalk (Figure 21B). Few sponges with ovoid or pyriform main bodies sitting on stalks. Papillae, if present, are weakly developed. Colour in life pale orange or yellowish. Syntypes of Quasillina richardi are small fragments, one on a stalk lacking the major part of the main body, the other being a residual of the main body.

Anatomy

In life choanosome is an intensive yellow or orange, unstructured, semi-fluid mass without any spicule tracts. This mass is often washed away under preservation. Choanosomal skeleton comprises free-scattered bundles of small spicules (Figure 21C). Cortex in life pale orange or pale yellow, leather-like. Cortical skeleton comprises a superficial palisade (150–200 µm thick) of bouquets of small spicules and two inner overlapping layers, a layer of criss-cross large spicules (270–300 µm thick) located midst in the cortex and an internal layer (35–80 µm thick) of longitudinal tracts of large spicules (Figure 21D). Skeleton of the papilla wall is the same as the cortical skeleton (Figure 21E).

Spicules

(Measurements based on 15 specimens)

Principal spicules – subtylostyles to styles, straight, or occasionally gently curved, fusiform. Length 570–862–1098 µm, maximum diameter 11.2–17.8–25.5 µm, N = 450.

Small spicules – styles to subtylostyles, often bent in the distal part, slender. Length 140–227–306 µm, maximum diameter of shaft 1.9–4.0–5.8 µm, N = 450.

Genetic data

Data obtained from five individuals of Quasillina brevis are identical in both genes studied. Quasillina brevis is closely related, especially in the CO1 phylogeny, to morphologically distinct Polymastia boletiformis (see the synapomorphies in the Genetic data section for the latter species above). At the same time Q. brevis possesses six autapomorphies in 28S rDNA distinguishing it from all other polymastiids (Online resource 3, p. 4) and, apart from them, differs from P. boletiformis by 18 bps in this gene (Matrix M34250 in TreeBase).

External morphology

Sponges thickly encrusting or cushion-shaped, the largest up to 100 cm². Surface shaggy, silted with sediment making it dirty greyish or brownish in colour. Up to 50 cylindrical or conical papillae, whitish in life, but usually becoming pale yellow, brownish or pinkish in alcohol. On soft bottoms living sponges are often completely covered by sediment with only erect papillae protruding above (Figure 23A). On hard bottoms the sponges may contract the papillae. After sampling and fixation the papillae always considerably contract and invaginate into the surface hispidation. Oscula not visible in preserved sponges.

Skeleton

Choanosome in life orange, dense. Main choanosomal skeleton composed of longitudinal tracts of principal spicules which cross the cortex and make up a dense and thick surface hispidation (Figure 23B). Auxiliary choanosomal skeleton comprises small, occasionally intermediary, spicules often arranged in bundles, 3–7 spicules each. Cortex in life whitish, dense, not detachable. Cortical skeleton composed of a 115–120 µm thick superficial palisade of small spicules and an internal layer (~210 µm thick) of tangentially arranged intermediary spicules (Figure 23B). In areas around papillae these layers are separated by an intermediate, aspicular zone (about 100 µm thick). Exotyles cross the cortex and join the surface hispidation. Walls of papillae lack the tangential cortical layer. Single intermediary spicules scattered both in the walls and in the bulkheads between canals.

Spicules

(Measurements based on 10 specimens)

Principal spicules – styles to subtylostyles, often polytylote straight, slender. Length 1100–2423–5000 µm, diameter of shaft 12.0–16.2–19.0 µm, N = 100.

Intermediary spicules – tylostyles, usually straight, occasionally curved, slightly fusiform. Length 200–502–796 µm, diameter of tyle 6.9–9.2–11.1 µm, proximal diameter of shaft 5.0–7.1–9.0 µm, maximum diameter of shaft 6.9–10.8–14.3 µm, N = 100.

Small spicules – tylostyles, straight or curved, usually slender. Length 94–125–160 µm, diameter of tyle 3.9–4.6–5.1 µm, diameter of shaft 3.0–3.5–4.0 µm, N = 100.

Exotyles slender, 5100–6117–7520 µm long, usually with weakly developed or completely reduced proximal tyles. Shafts 13.8–17.2–20 µm in maximum diameter. Distal knobs (14.1–19.9–27.0 µm in diameter) usually irregularly fungiform or umbrelliform (Figure 23C), more rarely hemispherical or spherical, occasionally with short protuberances on the edges, sometimes slightly displaced along the shaft or comprising several swellings. Surface of the knobs and the adjacent portions of the shafts rough, wrinkled, granulated or tuberculated.

Genetic data

Of the three individuals of Sphaerotylus borealis, from which genetic data were obtained, two sponges differ neither by CO1, nor by 28S rDNA. The third individual is distinguished by two bps in 28S rDNA (Matrix M34250 in TreeBase), but no CO1 was obtained from it. In both CO1 and 28S rDNA phylogenies S. borealis does not group with any of the congeners (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). The difference between S. borealis and the type species of Sphaerotylus, S. capitatus, is 26 bps in CO1 (Matrix M34248 in TreeBase) and 86 bps in 28S rDNA, excluding the intraspecific polymorphism in both species (Matrix M34250 in TreeBase). At the same time S. borealis possessing just one autapomorphy in 28S rDNA (Online resource 3, p. 3) forms a clade with two morphologically quite distinct species, Polymastia cf. conigera Bowerbank, Reference Bowerbank1874 (a British species not covered by the present study) and Weberella bursa (the type species of Weberella Vosmaer, Reference Vosmaer1885 described below) in both CO1 and 28S rDNA phylogenies (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). However, the Bayesian support for this clade is weak (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). These three species share just two synapomorphies in 28S rDNA distinguishing them from all other polymastiids (Online resource 3, p. 3, Matrix M34250 in TreeBase), while the differences between them are large. Sphaerotylus borealis differs from P. cf. conigera by 17 bps in CO1 (Matrix M34248 in TreeBase) and 35 bps in 28S rDNA (Matrix M34250 in TreeBase) and from W. bursa by 7 bps in CO1 (Matrix M34248 in TreeBase) and 33 bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Sponges thickly encrusting, cushion-shaped or massive, fist- or dome-shaped, occupying up to 50 cm² of the substrate. Surface velvety, knobbly, dark brown in colour, with up to 30 papillae (Figure 25A). Papillae of living sponges whitish or pale yellow in colour, conical, with small, scarcely visible oscula at the summits. In alcohol-preserved specimens the papillae may be considerably contracted looking like tubercles, while their colour does not change much.

Skeleton

Choanosome in life yellowish or pale orange, dense. Main choanosomal skeleton composed of radial or longitudinal tracts of principal spicules which enter the cortex (Figure 25B). Auxiliary choanosomal skeleton comprises small and intermediary spicules usually scattered singly or sometimes arranged in small groups. Besides these spicules some individuals possess exotyles between the choanosomal tracts (Figure 25C). Cortex in life whitish, firm, not detachable. Cortical skeleton composed of a superficial palisade (~110 µm thick) of small spicules, an internal layer (about 170 µm thick) of tangentially arranged intermediary spicules and a middle layer (180–190 µm thick) with a low concentration of spicules (Figure 25D). Exotyles cross the cortex forming a dense superficial layer with their distal knobs rising above the palisade. Papillae walls without internal cortical layer. Single intermediary spicules scattered both in the papillae walls and in the bulkheads between the canals.

Spicules

(Measurements based on five specimens)

Principal spicules – subtylostyles to styles, often polytylote, straight, slightly fusiform or slender. Length 650–998–1505 µm, diameter of tyle, if present, 10.0–12.8–16.0 µm, proximal diameter of shaft 8.9–11.5–15.1 µm, maximum diameter of shaft 14.0–19.5–26.0 µm, N = 50.

Intermediary spicules – tylostyles, straight or gently curved, slender or slightly fusiform. Length 314–484–650 µm, diameter of tyle 9.1–11.4–14.0 µm, proximal diameter of shaft 6.9–8.8–11.0 µm, maximum diameter of shaft 9.0–13.0–16.5 µm, N = 50.

Small spicules – tylostyles, straight or curved, usually slender. Length 96–155–221 µm, diameter of tyle 2.9–4.6–6.1 µm, proximal diameter of shaft 1.1–2.3–3.2 µm, maximum diameter of shaft 2.0–5.0–7.0 µm, N = 50.

Exotyles straight or gently curved, slender, 650–974–1250 µm long. Proximal tyles varying from well-developed (6.8–11.0–14.0 µm in diameter) to reduced. Distal knobs usually regularly spherical (Figure 25E), occasionally hemispherical or elongated, 18.0–22.8–30.0 µm in diameter. Surface of the knobs and the adjacent portions of the shafts usually rough, spined or granulated. Shafts gradually expanding towards the distal knobs, N = 50.

Genetic data

CO1 sequences obtained from three individuals of Sphaerotylus capitatus are identical (Matrix M34248 in TreeBase). 28S rDNA sequences obtained only from two of these sponges differ by two bps (Matrix M34250 in TreeBase) and exhibit one synapomorphy distinguishing S. capitatus from other polymastiids (Online resource 3, p. 4). In the CO1 and 28S rDNA phylogenies S. capitatus forms a clade with two British unidentified species, Sphaerotylus sp. 1 and Sphaerotylus sp. 2, not covered by the present study (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). These three species share three synapomorphies in CO1 (Online resource 2, p. 4, Matrix M34248 in TreeBase) and three synapomorphies in 28S rDNA (Online resource 3, p. 4, Matrix M34250 in TreeBase) distinguishing them from all other polymastiids. One more synapomorphy in 28S rDNA is shared only by S. capitatus and Sphaerotylus sp. 1 (Online resource 3, p. 4, Matrix M34250 in TreeBase). Meanwhile, S. borealis, a Nordic species described above, does not fall in this clade (see the differences between S. borealis and S. capitatus in the Genetic data section for the former species).

External morphology

Holotype and both paratypes hemispherical, with a minutely and unevenly hispid surface edged with a narrow spicule fringe and bearing a single weakly developed papilla with an osculum at the summit. Holotype 16–17 mm in diameter and ~9 mm in height, attached to a volcanic porous concretion (Figure 27A). Surface dirty grey, with a whitish papilla. Paralectotype ZMBN 098041 17–18 mm in diameter and ~6 mm in height, attached to a basalt piece (Figure 27B). Surface dirty grey, with a whitish papilla. Paratype ZMBN 098038 was, before dissection, 11 mm in diameter and 4 mm in height, attached to small gravels. Surface was brownish, with a yellowish papilla located in a small depression. Other sponges hemispherical, lenticular or irregular, up to 24 mm in diameter. Surface, for the most part, hispid, occasionally shaggy, dark brown or dark grey because of the covering sediment. A single papilla and the surrounding area on the body top, which may be gently depressed, are smooth and pale in colour. Marginal spicule fringe up to 3 mm wide in the largest individuals.

Anatomy

Choanosome in alcohol light or dark brown, dense. Main choanosomal skeleton composed of tracts (96–310 µm thick) of principal spicules radiating from the basal area, where the sponge is attached to the substrate, occasionally ramifying, crossing the cortex and protruding above the surface (Figure 27C). At the body edge the protruding tracts form a prominent fringe. Some tracts ascend to the papilla walls. Auxiliary choanosomal skeleton comprises free-scattered small and intermediary spicules, the latter occasionally gathered in small bundles. Cortex in alcohol whitish or pale brown, firm, not detachable. Cortical skeleton comprises a superficial palisade (217–300 µm thick) of small spicules. In the central area of the upper cortex there is also an internal layer (116–494 µm thick) of criss-cross intermediary spicules. Under the papilla the palisade and the internal layer are separated by an aquiferous cavity (~268–810 µm in diameter).

Spicules

(Measurements based on seven specimens, individual variation presented in Table 7)

Table 7. Individual variation of spicule dimensions of Spinularia njordi (given in μm as minimum–mean–maximum). Parameters: length, diameter of tyle, proximal diameter of shaft, maximum diameter of shaft, number of spicules measured (N).

Principal spicules (Figure 27D) – subtylostyles to tylostyles, usually straight and slender. Length 1116–1492–2579 µm, diameter of tyle (if present) 8.9–13.3–16.5 µm, proximal diameter of shaft 6.4–9.1–14.0 µm, maximum diameter of shaft 8.9–14.9–21.6 µm, N = 284.

Intermediary spicules (Figure 27E) – tylostyles to subtylostyles, usually straight, occasionally gently curved, slender. Length 422–685–1128 µm, diameter of tyle (if present) 8.9–13.0–16.5 µm, proximal diameter of shaft 5.1–7.9–11.4 µm, maximum diameter of shaft 8.9–13.3–17.8 µm, N = 254.

Small spicules (Figure 27F) – tylostyles, often gently bent at the proximal part, occasionally straight, usually slightly fusiform. Length 201–328–422 µm, diameter of tyle 8.9–12.6–16.5 µm, proximal diameter of shaft 3.8–7.8–12.7 µm, maximum diameter of shaft 8.9–13.3–20.3 µm, N = 253.

Genetic data

Data obtained from three individuals of Spinularia njordi are identical in both genes studied. Moreover, the CO1 sequences from S. njordi are identical to those from the type species of Spinularia, S. spinularia, and the Norwegian individuals of S. sarsii, but not the Mozambican S. cf. sarsii (Online resource 2, p. 5). At the same time S. njordi displays seven autapomorphies in 28S rDNA distinguishing it from the congeners (Matrix M34250 in TreeBase). Of these autapomorphies one is unique among all polymastiid species from which 28S rDNA has ever been obtained (Online resource 3, p. 5).

External morphology

Lectotype discoid, flattened, with hispid, grey upper and basal surfaces and a marginal spicule fringe (Figure 29A, B). Body ~9 mm in diameter (excluding the fringe) and ~6 mm thick. Upper surface bears four tiny papillae with oscula at the summits (Figure 29A). Basal surface without any trace of the substrate (Figure 29B). Fringe 1.5–4 mm wide. All paralectotypes externally resemble the lectotype. Paralectotype BMNH 1887.5.2.38.2 is a body sector with a 3.0–3.5 mm wide fringe and without papillae. Paralectotype BMNH 1887.5.2.40 discoid, ~9 mm in diameter, with a convex, smooth basal surface and a flattened, hispid upper surface bearing a single papilla damaged at the summit (Figure 29E, F). Fringe 1.5–2.5 mm wide. One of the paralectotypes BMNH 1887.5.2.61 flattened, irregular, ~6 × 8 mm, with hispid upper and basal surfaces and without visible papillae. Fringe 1–2 mm wide. The other paralectotype BMNH 1887.5.2.61 discoid, flattened, ~4 mm in diameter, with an almost smooth basal surface and a hispid upper surface bearing a single papilla. Fringe 0.7–3.0 mm wide. Paralectotype BMNH 1887.5.2.66 discoid, ~5.0–5.5 mm in diameter, with a convex, almost smooth basal surface and a flattened, strongly hispid upper surface lacking visible papillae (Figure 29C, D). Fringe 1.3–2.6 mm wide. Other sponges discoid, lenticular, hemispherical, occasionally irregular, up to 13 mm in diameter (Figure 29G, H). Upper surface flattened, hispid or shaggy, covered with sediment, bearing a single papilla, more rarely few, small papillae with oscula at the summits (Figure 29G). Basal surface often convex, smooth, attached to the substrate with a central point (Figure 29H). A small substrate may be plunged into the basal cortex. Some individuals are free of any substrates. Width of the marginal fringe may reach half of body diameter.

Anatomy

Choanosome in alcohol light or dark brown, dense. Main choanosomal skeleton composed of tracts (119–283 µm thick) of principal spicules radiating from the central basal point, crossing the upper cortex and protruding above the surface (Figure 29I). Some tracts ascend to the papilla walls. Auxiliary choanosomal skeleton comprises free-scattered bundles of intermediary spicules. Cortex in alcohol whitish, firm, not detachable. Skeleton of the upper cortex comprises a superficial palisade (about 300 µm thick) of small spicules, a middle space (340–405 µm thick) with low concentration of spicules except for ascending choanosomal tracts and an internal layer (100–110 µm thick) of criss-cross intermediary spicules. Skeleton of the basal cortex formed of peripheral tracts of principal spicules running parallel to the surface and free-scattered single small spicules. Extra-long spicules (exotyles) composing the marginal fringe are embedded in the tracts.

Spicules

(Measurements based on 13 specimens)

Principal spicules – styles, occasionally subtylostyles, usually straight and fusiform. Length 871–1787–2900 µm, maximum diameter of shaft 13.0–19.3–26.6 µm, N = 130.

Intermediary spicules – subtylostyles to tylostyles, usually straight, slightly fusiform. Length 250–471–632 µm, maximum diameter of shaft 6.1– 7.6–8.7 µm, N = 390.

Small spicules – tylostyles, often gently bent at the proximal part, fusiform. Length 152–232–298 µm, maximum diameter of shaft 8.1–9.8–10.4, N = 390.

Exotyles (spicules of the marginal fringe) – styles, occasionally subtylostyles, straight or slightly curved, fusiform. Length 3890–5010–6030, μm, maximum diameter of shaft 24.5–27.3–29.8 µm, N = 70.

Genetic data

Certain genetic differences are revealed between the morphologically very similar Spinularia sarsii from Norway and Spinularia cf. sarsii from Mozambique. Data obtained from two Norwegian individuals are identical in both genes studied. Moreover, the CO1 sequences from these individuals are identical to those from the type species of Spinularia, S. spinularia, and S. njordi and display one synapomorphy distinguishing them from other polymastiids including the Mozambican S. cf. sarsii (Online resource 2, p. 5). In 28S rDNA the Norwegian S. sarsii differs from S. spinularia by 6 bps and from S. njordi by 12 bps (Matrix M34250 in TreeBase) and shares with them two synapomorphies (Online resource 3, p. 5). At the same time the Mozambican S. cf. sarsii is distinguished from all polymastiids by three autapomorphies in CO1 (Online resource 2, p. 5). Apart from these autapomorphies, it differs from the congeners by five bps in CO1 (Matrix M34248 in TreeBase). In 28S rDNA the Mozambican S. cf. sarsii differs from the Norwegian S. sarsii by 13 bps, from S. njordi by 18 bps and from S. spinularia by 14 bps (Matrix M34250 in TreeBase).

External morphology

Lectotype of Tethea spinularia cushion-shaped, ~23 × 15 × 12 mm, removed from the substrate (Figure 31A). Surface rough, beige in the central area and grey in the periphery, bearing 11 wart-like papillae, most with oscula at the summits. The most intact paralectotype cushion-shaped, ~9 × 8 × 5 mm, removed from the substrate. Surface minutely hispid, covered with grey sediment in the periphery and clean, pale orange in the central area around a single wart-like papilla. Two paralectotypes are fragments of cushion-shaped sponges with minutely hispid surface, without papillae, removed from the substrates. The smallest paralectotype is a tiny encrust on a stone. Holotype of Rhaphidorus setosus cushion-shaped, about 12 mm in diameter, considerably damaged, attached to a stone. Scandinavian sponges cushion-shaped, occupying up to 9 cm² of the substrate (Figure 31B). Surface minutely hispid, occasionally smooth and free of sediment in the central area and more hispid and covered with sediment in the periphery, bearing up to 15 papillae. Many individuals with tiny spicule fringes at the body edges. Papillae small, usually wart-like, with oscula at the summits.

Anatomy

Description is based on the lectotype of Tethea spinularia and Scandinavian individuals. Anatomy of the holotype of Rhaphidorus setosus is not studied because of its considerable damage. Choanosome in life pale orange, dense. Main choanosomal skeleton composed of tracts (72–380 µm thick) of principal spicules radiating from the base, crossing the cortex and protruding above the surface (Figure 31C). Some tracts ascend to the papilla walls. Auxiliary choanosomal skeleton comprises free-scattered bundles of small spicules spread all over the body, bundles of principal spicules concentrated in the basal area and lying perpendicular to the main tracts, and trichodragmata (dense packs, 69–391 long and 56–453 µm wide) of raphides concentrated in the subcortical area (Figures 31D & 32C–D). Cortex in life whitish, cream-coloured or pale brown, firm, not detachable. Cortical skeleton comprises a superficial palisade (368–643 µm thick) of small spicules and an inner space (256–1128 µm thick) with low concentration of spicules, both reinforced with the ascending choanosomal tracts. Papilla wall covered with a superficial palisade.

Spicules

Lectotype of Tethea spinularia, two Swedish individuals and seven Norwegian individuals:

Principal spicules (Figure 32A) – tylostyles with roundish, occasionally oval, tyles, usually straight and slender. Length 404–758–1355 µm, diameter of tyle 6.8–9.3–14.4 µm, proximal diameter of shaft 3.2–6.0–10.0 µm, maximum diameter of shaft 5.8–10.0–14.6 µm, N = 300.

Small spicules (Figure 32B) – tylostyles, straight or occasionally gently bent, slightly fusiform. Length 161–290–373 µm, diameter of tyle 6.6–8.8–11.5 µm, proximal diameter of shaft 2.8–5.6–7.8 µm, maximum diameter of shaft 5.4–8.8–13.4 µm, N = 300.

Raphides (Figure 32C–G) – thin monactines with one tip acerated (Figure 32G) and the other harpoon-shaped, with a blunt point and a lateral barb (Figure 32F). Length 65–79–85 µm, maximum diameter of shaft 0.3–0.4–0.4 µm, N = 200.

Holotype of Rhaphidorus setosus:

Principal spicules (Figure 32H) – tylostyles with roundish, occasionally oval, tyles, usually straight and slightly fusiform. Length 548–1458–2185 µm, diameter of tyle 10.5–16.2–20.2 µm, proximal diameter of shaft 7.4–14.1–19.5 µm, maximum diameter of shaft 11.9–17.5–22.8 µm, N = 30.

Small spicules (Figure 32I) – tylostyles, usually straight and slender. Length 216–252–330 µm, diameter of tyle 11.1–11.7–12.5 µm, proximal diameter of shaft 7.2–7.7–8.4 µm, maximum diameter of shaft 10.9–12.0–12.7 µm, N = 30.

Raphides (Figure 32J) – thin monactines with one tip acerated and the other bearing an umbrelliform (Figure 32K) or subspherical ornamentation (Figure 32L) with tiny jags along the edge. Length 233–245–260 µm, maximum diameter of shaft 1.0–1.2–1.3 µm, N = 20.

Genetic data

28S rDNA was obtained from five individuals of Spinularia spinularia, while CO1 was sequenced only from four of them. The CO1 sequences are identical, but a polymorphism is revealed in 28S rDNA. Two subspecies groups, one comprising three individuals and the other two individuals, differ by two bps in this gene (Matrix M34250 in TreeBase). The synapomorphies and distinctions of S. spinularia from the congeners are described in the Genetic data sections for S. njordi and S. sarsii.

External morphology

Holotype fungiform, ~16 mm high and 13–15 mm in diameter, removed from the substrate (Figure 34A, B). Lateral surface smooth, pale beige (Figure 34A). Upper surface minutely hispid, beige, with four small exhalant papillae at the summit (Figure 34B). Other sponges columnar, fungiform, occasionally drum-shaped, up to 35 mm high and 30 mm in diameter, with distinct difference between the smooth, palely coloured lateral surface and the more or less hispid, phaeochrous upper surface bearing one to 20 exhalant papillae. In some individuals the papillae considerably stretched, thread like, with the length exceeding the height of the main body by several times. When growing on soft sediments, the sponges often form long root-like structures made of spicule bundles.

Anatomy

Choanosome in life pale orange, pale yellow or light brown, dense. Main choanosomal skeleton composed of longitudinal tracts (430–1000 µm thick) of principal spicules running from the base, branching and entering the cortex (Figure 34C). Some tracts ascend to the papilla walls. No auxiliary choanosomal skeleton observed. Cortex in life whitish or light beige, firm, not detachable. Skeleton of the lateral cortex (500–780 µm thick) is a dense layer of criss-crossed intermediary spicules. Skeleton of the upper cortex (1000–1600 µm thick) comprises radiating tracts of principal spicules ascending from the choanosome perpendicular to the surface and a superficial palisade (450–650 µm thick) of small spicules.

Spicules

(Measurements based on 15 individuals)

Principal spicules – subtylostyles to tylostyles, usually straight and slender. Length 956–1642–2400 µm, maximum diameter of shaft 13.2–20.8–25.2 µm, N = 450.

Intermediary spicules – tylostyles, straight, fusiform. Length 810–955–1138 µm, maximum diameter of shaft 20.5–24.7–31.2 µm, N = 450.

Small spicules – tylostyles, straight, fusiform. Length 274–467–670 µm, maximum diameter of shaft 12.8–16.8–19.8 µm, N = 450.

Genetic data

In the CO1 phylogeny Tentorium semisuberites is the sister to the clade of Spinularia spp., but in the 28S rDNA it has no close relations (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). At the same time T. semisuberites possesses just one autapomorphy in CO1 distinguishing it from all other polymastiids (Online resource 2, p. 5). Moreover, an intraspecific polymorphism in both genes is observed in this species. The two individuals, from which the data were obtained, differ by two bps in CO1 (Matrix M34248 in TreeBase) and four bps in 28S rDNA (Matrix M34250 in TreeBase).

External morphology

Massive, fist-shape, or occasionally globular sponges occupying up to 100 cm² of the substrate (Figure 36A, B). Surface smooth, white or pale cream both in life and alcohol, with up to 200 papillae, all with oscula at the summits. The papillae conical, 2–8 mm long, up to 8 mm wide at base and 2 mm wide at summit.

Anatomy

Choanosome crumbly, pale yellow in life, but becoming slightly darker in alcohol. Main choanosomal skeleton composed of reticulating tracts (47–254 µm thick) of principal spicules (Figure 36C). Some tracts ascend to the cortex and the papillae. Auxiliary choanosomal skeleton comprises free-scattered small spicules. Cortex both in life and alcohol whitish, firm, but detachable. Cortical skeleton includes a superficial palisade (246–337 µm thick) composed of tufts of small spicules, a middle layer (513–1011 µm thick) with aquiferous cavities separated by the ascending and radiating choanosomal tracts and an internal layer (100–233 µm thick) of obliquely lying small spicules (Figure 36D). The cortical palisade and the internal layer stretch to the papillae walls. Each papilla has a large central exhalant canal and numerous small inhalant canals in the periphery. Bulkheads separating the canals reinforced with the ascending tracts of principal spicules and free-scattered small spicules.

Spicules

(Measurements based on 12 individuals)

Principal spicules – subtylostyles, occasionally styles, usually straight and slender. Length 407–538–700 µm, diameter of tyle 8.8–11.0–13.0 µm, proximal diameter of shaft 7.4–9.6–12.5 µm, maximum diameter of shaft 8.8–11.0–12.6, N = 360.

Small spicules – tylostyles, occasionally subtylostyles, usually straight and slender. Length 90–201–273 µm, diameter of tyle 2.5–4.8–7.7 µm, proximal diameter of shaft 1.9–3.3–5.0 µm, maximum diameter of shaft 1.9–3.6–5.3, N = 360.

Genetic data

Two individuals of Weberella bursa, from which the genetic data were obtained, differ neither by CO1, nor by 28S rDNA. In the phylogenies based on these genes W. bursa is the sister to morphologically quite distinct Polymastia cf. conigera (a British species not covered by the present study), although the Bayesian support for this relationship is weak (Plotkin et al., Reference Plotkin, Voigt, Willassen and Rapp2016b). These species share two unique synapomorphies in CO1 (Online resource 2, p. 3, Matrix M34248 in TreeBase) and three synapomorphies in 28S rDNA, of which one is unique and two are also shared by Sphaerotylus borealis (Online resource 3, p. 3, Matrix M34250 in TreeBase). The difference between W. bursa and P. cf. conigera is 13 bps in CO1 (Matrix M34248 in TreeBase) and five bps in 28S rDNA (Matrix M34250 in TreeBase). The distinctions between W. bursa and S. borealis are described in the Genetic data section for the latter species.