A new species of the genus Plagiorhynchus Lühe, 1911 from the intestine of the long-billed curlew (Numenius americanus) from northern Mexico is described. Plagiorhynchus (Plagiorhynchus) aznari n. sp. is morphologically distinguished from other congeneric species from the Americas by having a trunk expanded anteriorly and a cylindrical proboscis, armed with 19 longitudinal rows of hooks, with 14–15 hooks each row. Nearly complete sequences of the small subunit and large subunit of the nuclear ribosomal DNA of the new species were determined and compared with available sequences from GenBank. Phylogenetic analyses inferred from the two molecular markers consistently showed that P. (Plagiorhynchus) aznari n. sp. is closely related to P. (Plagiorhynchus) allisonae, and this clade is sister to a clade formed by P. (Prosthorhynchus) transversus and P. (Prosthorhynchus) cylindraceus from Plagiorhynchidae. The new species represents the second record of the genus in Mexico and the fourth species in the Americas. The phylogenetic relationships among the members of the order Polymorphida in this study provide significant insights into the evolution of ecological associations between parasites and their definitive hosts. Our analyses suggest that the colonization of marine mammals, fish-eating birds and waterfowl in Polymorphidae might have occurred independently, from a common ancestor of Centrorhynchidae and Plagiorhynchidae that colonized terrestrial birds and mammals.

We describe the infectivity, virulence, cultivating conditions, and phylogenetic positions of naturally occurring oomycete parasites of Daphnia, invertebrates which play a major role in aquatic food webs. Daphnia pulex individuals were found dead and covered by oomycete mycelia when exposed to pond sediments. We were able to extract 4 oomycete isolates from dead Daphnia and successfully cultivate them. Using the ITS and LSU rDNA sequences, we further showed these isolates to be distinct species. The isolates were experimentally demonstrated to be parasitic and not saprobic. After exposure to the parasites, Daphnia mortality was much higher than that reported for Daphnia infected with other known parasite species. Therefore, it is likely that oomycete parasites are important selective pressures in natural Daphnia populations. Moreover, their close phylogenetic relationship to parasites of fish and algae suggests that the stability of aquatic food webs (i.e. fish–Daphnia–algae) might be influenced by the shared parasite communities.

A phylogenetic study using large subunit ribosomal DNA sequence data of several species of Siphula, representing all phenotypically recognized species groups, suggests that Siphula is not monophyletic. One lineage, including the core group related to S. ceratites and the S. decumbens group, is placed with members of the Icmadophilaceae, whereas a second distinct lineage, comprising S. complanata, S. fragilis and their relatives, has evolved within the Coccotremataceae. To accommodate these species, the new genus Parasiphula is described as new to science. Parasiphula consists of species restricted to cool to cold latitudes of the Southern Hemisphere. The results show a remarkable case of parallel evolution of lineages that have lost sexual stages and propagate via thallus fragments.

The D1-D2 domains of LSU rDNA were used to reconstruct the phylogenetic relationships within the Ancyrocephalinae (Monogenea: Dactylogyridae) utilizing maximum-parsimony (MP), maximum-likelihood (ML), minimum evolution (ME) and neighbour-joining (NJ) methods. A total of 32 monogenean taxa were examined in the present study, including 9 Haliotrema species and 13 other species representing the Ancyrocephalinae, 4 Thaparocleidus species representing the Ancylodiscoididae, and 6 species representing the Diplectanidae which were used as multiple outgroups. All 4 analyses (i.e. MP, ML, ME and NJ) inferred the same interrelationship pattern: (Diplectanidae, (Ancylodiscoididae, Dactylogyridae)) with high bootstrap support. However, 9 Haliotrema species were dispersed to form 4 clades together with species from other genera, indicating the apparent non-monophyly of Haliotrema. Three major groups were defined based on reconstructed phylogenetic trees to explain the radiation of Haliotrema species. The morphology of the reproductive organ, particularly the male copulatory organ (MCO), was discussed to further understand the formation of each group. (1) Results of the present study indicated an intimate relationship among Metahaliotrema (2 species), Protogyrodactylus (4 species) and Haliotrema (2 of 9 species), and notably, all these species share vagina-absence. (2) Based on the present molecular analyses and the morphological characters of the MCO, we propose to transfer H. spirotubiforum and the undetermined Haliotrema sp. ZHDDb to Euryhaliotrema as new combinations. (3) We propose to erect a new genus to accommodate the Haliotrema species with horn-like shaped MCO. Taxonomic implications of the present molecular phylogenetic analyses are discussed. A wider range of taxa and more DNA markers displaying various evolutionary rates should be used to estimate phylogenetic relationships among species within the Ancyrocephalinae and Ancylodiscoididae in further studies.

Trypanosoma (Herpetosoma) grosi, which naturally parasitizes Apodemus spp., can experimentally infect Mongolian jirds (Meriones unguiculatus). Three isolates from A. agrarius, A. peninsulae, and A. speciosus (named SESUJI, HANTO, and AKHA isolates, respectively) of different geographical origin (AKHA from Japan, and the others from Vladivostok), exhibited different durations of parasitaemia in laboratory jirds (2 weeks for HANTO, and 3 weeks for the others). To assess the genetic background of these T. grosi isolates, their small (SSU) and large subunit (LSU) ribosomal RNA genes (rDNA) were sequenced along with those of 2 other Herpetosoma species from squirrels. The SSU rDNA sequences of these 3 species along with available sequences of 3 other Herpetosoma trypanosomes (T. lewisi, T. musculi and T. microti) seemed to reflect well the phylogenetic relationship of their hosts. Three isolates of T. grosi exhibited base changes at 2–6 positions of 2019-base 18S rDNA, at 5–29 positions of 1817/1818-base 28Sα rDNA, or 1–5 positions of 1557–1559-base 28Sβ rDNA, and none was separated from the other 2 isolates by rDNA nucleotide sequences. Since base changes of Herpetosoma trypanosomes at the level of inter- and intra-species might occur frequently in specified rDNA regions, the molecular analysis on these regions of rodent trypanosomes could help species/strain differentiation and systematic revision of Herpetosoma trypanosome species, which must be more abundant than presently known.

The genus Pseudo-nitzschia includes several species capable of producing domoic acid, the causative agent of Amnesic Shellfish Poisoning. Some of these species have been recorded frequently in the Gulf of Naples. For one of the species, P. multistriata, which has been recurrently found in our sampling area since 1995, this is the first report for European waters. Here we provide further details on the fine structure of this species. Pseudo-nitzschia multistriata was the only one found to produce domoic acid among all the Pseudo-nitzschia species from the Gulf of Naples, and this finding raises the number of potentially toxic species in this genus to nine. Phylogenetic relationships among several Pseudo-nitzschia species were assessed using the hypervariable domains (D1–D3) of the large subunit (LSU) rDNA. The match between the phylogeny obtained and important taxonomic characters used in this genus are discussed. Results show that P. multistriata clusters with wider species lacking a central larger interspace in the raphe. Close genetic relationships were determined between P. fraudulenta and P. subfraudulenta, and between P. pungens and P. multiseries. Genetic differences among these pairs of species are comparable to those among isolates of P. pseudodelicatissima from the Gulf of Naples, indicating high intraspecific genetic diversity of Pseudo-nitzschia species in the relatively conserved LSU region. This could explain the problematic results obtained when testing a match between species-specific Pseudo-nitzschia LSU probes and our sequences.

A new member of Delesseriaceae (Ceramiales, Rhodophyta) is described from Southern Taiwan and the Philippines. On the basis of comparative vegetative and reproductive morphology, and phylogenetic analysis inferred from nuclear-encoded large-subunit ribosomal DNA sequences (LSU rDNA), we conclude that it belongs in the genus Drachiella, tribe Schizoserideae, subfamily Phycodryoideae. The new taxon shares with other Drachiella species the absence of macro- and microscopic veins; diffuse growth by marginal and intercalary meristematic cells; a polystromatic, lobed thallus; abundance of rhizoidal marginal proliferations used for attachment; convoluted plastids in surface cells; abundant secondary pit connections among adjacent vegetative cells; large intercellular spaces between surface cells; procarps confined to the upper side of the thallus, circular in outline, consisting of a supporting cell bearing a strongly curved carpogonial branch and two sterile groups that remain undivided; vertical division of gonimoblast initial from auxiliary cell, and unilateral, monopodial branching of gonimoblasts; and mature cystocarps with a massive candelabrum-like fusion cell of fused gonimoblasts bearing carposporangia in branched chains. It is distinguished from the other members of the genus by thalli that consist of extensive tangled mats of prostrate and overlapping decumbent blades, procarps confined to the upper side of the thallus, and the lack of basal stalks or stipes. Whereas the Schizoserideae is predominantly a Southern Ocean tribe, one of the tribe's four genera, Drachiella, was known only from the eastern Atlantic and Mediterranean. We herein report the first record of the genus for the Indo-Pacific Ocean, and describe Drachiella liaoii, sp. nov., as a fourth species in the genus.

In order to elucidate the phylogeny and evolutionary history of the Bacillariaceae we conducted a phylogenetic analysis of 42 species (sequences were determined from more than two strains of many of the Pseudo-nitzschia species) based on the first 872 base pairs of nuclear-encoded large subunit (LSU) rDNA, which include some of the most variable domains. Four araphid genera were used as the outgroup in maximum likelihood, parsimony and distance analyses. The phylogenetic inferences revealed the Bacillariaceae as monophyletic (bootstrap support [ges ]90%). A clade comprising Pseudo-nitzschia, Fragilariopsis and Nitzschia americana (clade A) was supported by high bootstrap values ([ges ]94%) and agreed with the morphological features revealed by electron microscopy. Data for 29 taxa indicate a subdivision of clade A, one clade comprising Pseudo-nitzschia species, a second clade consisting of Pseudo-nitzschia species and Nitzschia americana, and a third clade comprising Fragilariopsis species. Pseudo-nitzschia as presently defined is paraphyletic and emendation of the genus is probably needed. The analyses suggested that Nitzschia is not monophyletic, as expected from the great morphological diversity within the genus. A cluster characterized by possession of detailed ornamentation on the frustule is indicated. Eighteen taxa (16 within the Bacillariaceae) were tested for production of domoic acid, a neurotoxic amino acid. Only P. australis, P. multiseries and P. seriata produced domoic acid, and these clustered together in all analyses. Since Nitzschia navis-varingica also produces domoic acid, but is distantly related to the cluster comprising the Pseudo-nitzschia domoic acid producers, it is most parsimonious to suggest that the ability of species in the Bacillariaceae to produce domoic acid has evolved at least twice.