We describe a new specimen of the aïstopod Oestocephalus from Five Points, Ohio, which preserves much of the posterior braincase. The specimen, the largest aïstopod skull described, preserves the postorbital region to the occiput. The posterior braincase has coossified the basioccipital, exoccipitals, and opisthotic. The parasphenoid is rostrally restricted, toothless, and highly vaulted along the cultriform process. The lateral walls of the cultriform process are further reinforced by large longitudinally running, ventral flanges from the parietals. Two large endochondral ventral projections from the basioccipital, previously interpreted as basal tuberosities for hypaxial muscle insertion, are here instead interpreted as articulations for the branchial skeleton. This interpretation is further supported by traces of vasculature that is consistent with what is seen in gill-bearing species. A model for the reorganisation of the basicranial region on the transition from hyomandibula to stapes is proposed, which suggests that gills, or gill-support skeletal elements, might be further distributed along the tetrapod stem than previously thought. These data further support the placement of aïstopods in the tetrapod stem group and require a reconsideration of our understanding of early tetrapod evolution.

This study constitutes a first attempt to investigate sex differences in osmoregulatory capacity and metabolic responses in relation to hyper- and hypo-osmoregulation in the intertidal euryhaline crab Uca tangeri. Adult male and female specimens from Cadiz Bay, Spain (36°23′–37′N 6°8′–15′W), were acclimated to three different environmental salinities (12, 33 and 55 psu) during 7 days, and several parameters were assessed in haemolymph (osmolality, glucose, amino acids, triglycerides and lactate) as well as in metabolic key organs (hepatopancreas, anterior and posterior gills: glycogen, free glucose, amino acids and triglycerides). Specimens from both sex exhibited high and similar hyper- and hypo-osmoregulatory capacities. However, metabolite levels were differentially affected upon acclimation to low and high salinity in several metabolic organs and haemolymph of male and females: (i) glycogen in gills, (ii) free glucose in gills and hepatopancreas, (iii) amino acids in hepatopancreas, (iv) triglycerides in haemolymph, hepatopancreas and posterior gills, and (v) lactate in haemolymph. The results suggest the occurrence of differential metabolic adjustments upon hyper- and hypo-osmoregulation related to sex in the intertidal euryhaline crab U. tangeri.

Evidence of interference competition between the eimeriorin coccidian Aggregata sp. and the octopicolid copepod Octopicola superba at the level of the gills of naturally infected Octopus vulgaris is evaluated. Numerical and functional responses are considered for analysis, and the fundamental and realized spatial niches (FSNs and RSNs) are measured as part of the study. While it was not possible to measure the FSN of Aggregata sp., the analysis of the infection levels of O. superba recorded for non-concomitantly and concomitantly infected hosts suggests that the gills and body skin constitute, respectively, the main and accessory sites of infection of the parasite. According to the evidence found, the gills function mainly as an accessory site of infection of Aggregata sp., in specimens in which the caecum and intestine are massively infected. Evidence for a negative interaction between Aggregata sp. and O. superba has been found while controlling for a potential confounding effect of host size. Furthermore, the presence of O. superba on gill lamellae appears to have been negatively affected by the presence of Aggregata sp., while this latter remained mostly undisturbed. The mean number of oocysts of Aggregata sp. in the gills was higher in spring and summer, which were also the seasons presenting the broadest RSN for O. superba.

The morphologies of the hyobranchial apparatus in early tetrapods are reviewed, based primarily on first-hand examination and supplemented by published descriptions. The basic arrangement of the “aquatic” hyobranchium, with four pairs of branchial arches and internal gills, was conserved to a remarkable degree across the fish–to–tetrapod transition and was retained in further evolution in adults of several tetrapod lineages. Thus, a fish-like hyobranchium in basal tetrapods does not necessarily represent a larval or paedomorphic character, respectively, as was often suggested in analogy to extant salamanders. Rather, it represents the plesiomorphic state of the adult hyobranchium in tetrapods. The changes in the hyobranchium during the fish–to–tetrapod transition include the reduction of the number of skeletal elements and their morphological simplification. In all three presently discussed scenarios of lissamphibian origin, the temnospondyl, lepospondyl and diphyly hypotheses, the internal gills were reduced independently within temnospondyls and on the amniote stem below seymouriamorphs. Evidence of remodelling into a true “terrestrial” hyobranchium, with reduction of the posterior branchial arches and modification to support terrestrial tongue feeding, is scarce in early tetrapods. It evolved within temnospondyls in zatracheids, amphibamids and lissamphibians, as well as once or several times in early amniotes or in their immediate stem-forms.

The main purpose of this study was to establish the pattern of variability of some hemato-immunological parameters in the mangrove oyster, Crassostrea rhizophorae, from 3 different environmental conditions in Santa Catarina Island: two natural habitats (mangrove and rocks of the coastal bay) and one oyster culture station. The water quality was adequate in all localities. The animals were collected seasonally over a period of one year (n = 30, per locality). The oyster hemolymph comprised two basic cell populations, hyaline (HH) and granular hemocytes (GH). Both cell populations contained carbohydrates and glycogen in their cytoplasm (periodic acid Schiff reaction, PAS staining) and the occurrence of lysosomes was suggested by the detection of acid phosphatase (Gomori's method). Both hemocyte populations were able of phagocytosis of zymosan particles in vitro and producing cytotoxic molecules, such as the superoxide anions (nitroblue-tetrazolium, NBT reduction). The oyster hemograms significantly differed in the different habitats and also among seasons. The total circulating hemocyte counts (THC) and the percentage of GH in the mangrove and rock oysters always differed from each other, but not from those of the cultured oysters. The highest THC and the lowest percentage of GH were always found in summer. The total plasma protein concentration (PC) exhibited a similar seasonal pattern in all oyster populations, with a marked decrease in spring. The PC of the cultured oysters was almost always significantly lower than that of the other oyster populations. The plasma agglutinating titer was higher in the cultured oysters regardless of season. The histological organization of the oyster digestive gland and gills was basically similar to that of other oyster species. Their structural aspect did not show any detectable alteration, corroborating that the oysters were in good health. The results of this study will serve as a basis for further analyses on the monitoring of C. rhizophorae health status and environmental quality in different aquatic habitats.

The burrowing habits of thalassinidean shrimps presuppose their high susceptibility to the deleterious effects of gill fouling by particulate debris and epibionts. The structures and strategies used to prevent gill fouling were examined in Nihonotrypaea japonica and Upogebia major by morphological inference and aquarium observations. The gill complement of both species consists of 10 arthrobranchs, with flattened filaments of the phylloid trichobranch type. Nihonotrypaea japonica and U. major lack passive gill-cleaning setal systems in the branchial chamber, but were found to actively groom gills by inserting and brushing the gill filaments with a pad of dense setae on the distal segments of their fifth pereiopods (P5 brush). Grooming setae of the P5 brush in N. japonica are of serrate and plumose types, whereas they are serrate and pappose in U. major. Serrate setae with distally curved spiniform denticules were morphologically similar in both species. Phylogenetic mapping of the gill-cleaning mechanisms suggests that gill-cleaning characters are homoplasic and systematically conservative among the families of the Thalassinidea.

Des bivalves d'eau douce, Anodonta cygnea L., ont été récoltés dans une station de référence et transférés sur trois stations situées en amont (1) et en aval (2) d'une usine de pâte à papier blanchissant au chlore. Durant les 91 jours de l'expérience, de l'eau et des anodontes sont prélevés régulièrement au niveau des trois stations et les micropolluants organo-halogénés sont déterminés à l'aide des paramètres de groupe AOX et EOX. La qualité générale de l'eau se dégrade à l'aval des rejets de l'usine et présente une contamination chronique par les AOX, dont les concentrations moyennes sont multipliées par un facteur 9 à 16 par rapport à la station amont. Les anodontes exposés au niveau de la station amont ne montrent pas de variations significatives des concentrations en EOX. Par contre, une accumulation progressive des EOX est observée dans les branchies, les glandes digestives et les gonades chez les anodontes exposés à l'aval des rejets. Les facteurs d'accumulation, calculés comme le rapport entre les concentrations finales et les concentrations initiales, varient de 3.5 à 7.4 selon l'organe et la station considérée.

Conchyliocarida, from the Jurassic of France, have a conch-like carapace enclosing the whole body. The number of their somites, identified by the visible appendages, excludes them from Malacostraca. Caridean-like characters, including the large lamellar gills, bring them nearer to Malacostraca, end exclude them from other Classes. Their large functional compound eyes and the morphology of their limbs suggest a benthic life and predatory behaviour.

Conchyliocarida are represented by several forms at La Voulte sur Rhône, which are compared and contrasted to related forms elsewhere.