Guitartia tridentata n. gen., n. sp (monhysterida: xyalidae) and macrodontium gaspari n. gen., n. sp (chromadorida: microlaimidae), free-living marine nematodes from the Caribbean sea

Two new genera of free-living marine nematodes are described from the muddy bottom of Cienfuegos Bay, Caribbean Sea. Guitartia n. gen. (Xyalidae, Monhysterida) is characterised by three long tooth-like structures in the stegostom, second and third circle of anterior sensilla separate and posterior genital branch of the female restricted to a long post-vulvar sac. The type species is Guitartia tridentata n. gen., n. sp. Within the Xyalidae, Guitartia n. gen. is morphologically close to Amphimonhystrella, Cobbia, Elzalia, Scaptrella and Valvaelaimus, all being characterised by sclerotised structures in the stoma and transverse striation of the body cuticle. Main features for discrimination are the type of stoma structure, the shape and relative size of amphidial fovea, the presence of a post-vulvar sac and gubernacular apophyses and the absence of terminal setae on the tail. Macrodontium n. gen. (Microlaimidae, Chromadorida) is characterised by a heavily sclerotised stoma with one large dorsal tooth and two smaller subventral teeth, sexual dimorphism in size and position of the amphidial fovea and males with a single anterior testis. The type species is Macrodontium gaspari n. gen., n. sp. Within the Microlaimidae, Macrodontium n. gen. is similar to the genera Acanthomicrolaimus and Bolbolaimus due to sclerotised stoma and presence of large dorsal tooth. The new genus is similar to Aponema in sexual dimorphism in the size of the amphidial fovea, monorchic males, presence of a gubernacular apophysis and conico-cylindrical tail shape. Morphological characters of diagnostic value within the family are the ornamentation of the body cuticle, relative length of cephalic sensilla, stoma sclerotisation and number of testes

Juvenile Hippocampus guttulatus from a neuston tow at the French-Belgian border

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Three new Chromadoropsis species (Nematoda, Desmodoridae) from Southern Africa and the North Sea

Three new Chromadoropsis species with four pharyngeal bulbi are described from Southern Africa, Namibia (S.W.A.) and the North Sea. C. granulosus sp.nov. is described from a sandy beach near Port Elizabeth. This species is characterized by a very distinct layer of yellow granules just below the cuticle. C. namibiensis sp.nov. is described from a sandy beach at Langstrand, Namibia. This species can be distinguished by the length and shape of the gubernaculum and spicules as well as the size of the capitulum. C. longispiculosa sp.nov. is described from the North Sea and is characterized by the long spicules and the presence of numerous porids. The genus Chromadoropsis Filipjev, 1918 is revised

Procamacolaimus tubifer Gerlach, 1953, Procamacolaimus africanus sp.nov. and Eontolaimus capensis gen.nov., sp.nov., (Nematoda, Leptolaimidae) from South Africa

A female and three males of Procamacolaimus tubifer Gerlach, 1953 are described and illustrated from Cape Receife Beach, Port Elizabeth. P. africanus sp.nov. is also described from Cape Receife Beach. It is compared with P. tubifer which it resembles but from which it can be differentiated by length of the buccal cavity, amphid size and the shape of the spicules. Eontolaimus capensisgen.nov., sp.nov. is described, also from the same sandy beach. This new genus is related to Deontolaimus papillatus de Man, 1880 from which it can be distinguished, among other things, by the absence of a tooth-like structure in the buccal cavity and the presence of pre-anal tubuli

Spiniferaphonte, a new genus of Laophontidae (Copepoda: Harpacticoida), with notes on the occurrence of processes on the caudal rami

A new genus and species of Laophontidae, Spiniferaphonte ornata n. gen., n. sp., is described from the coast of Kenya. The new genus is closely related to Laophontina and Wellsiphontina as shown by the following synapomorphies: a denticulate operculum, a sexually dimorphic P4 exopod (reduced chaetotaxy of the ultimate segment in the male), and the absence of sexual dimorphism in the P2 and P3 endopods. The two-segmented exopod of PI and the presence of a seta on the endopodal part of the male P5 are plesiomorphies indicating that the new genus represents a separate lineage within this group. The proposal of the new genus Spiniferaphonte is supported by the following autapomorphies: three smooth setae on the female P5 exopod and a robust, dorsally bent, and strongly sclerotised caudal seta V. Within the Laophontidae, it is striking that the presence of distinct, thorn-like processes on the caudal rami is limited to interstitial genera. Distinct processes on the proximal segments of the antennule and a proximally thickened caudal seta V also appear to be associated with this interstitiality. These structures may play a role in the movement and the anchoring of the animals in their interstitial habitat

Two new genera of Laophontidae (Copepoda: Harpacticoida) without sexual dimorphism in the endopods of the swimming legs

Two new monospecific genera of the harpacticoid family Laophontidae T. Scott, 1905 are described here. Apistophonte wasiniensis gen. et sp. n. was found along the Kenyan coast and Propephonte duangitensis gen. et sp. n. along the northern coast of Papua New Guinea. They differ from most other laophontid genera in the absence of sexual dimorphism in the endopods of the swimming legs. At first sight, both new species resemble each other very closely in habitus, integumental ornamentation, chaetotaxy of the swimming legs and absence of sexual dimorphism in the endopods. However, the detailed characteristics of A1, maxilla and male P5 show that the species are not congeneric. The structure of the first antennular segment of Propephonte gen. n. suggests a close relationship with Peltidiphonte Gheerardyn and Fiers, 2006. The exact affinities of Apistophonte gen. n. however remain difficult to assess

A morphometric analysis of the genus Terschellingia (nematoda, Linhomoeidae) with redefinition of the genus and key to the species

The cosmopolitan and often ecologically dominant genus Terschellingia (Nematoda, Linhomoeidae), with 37 nominal species, is taxonomically a problematic taxon. Its species show high morphological plasticity, possess few diagnostic morphological characters and identification keys are lacking. A revision of the genus was carried out based on morphological and morphometric data from the literature and from light and electron microscopic observations of specimens collected in Cienfuegos Bay, Caribbean Sea, Cuba. The diagnosis of the genus Terschellingia is emended. Of the current 37 nominal species, 15 are considered as valid species based on morphological characters related to size and position of amphidial fovea, presence/position of cephalic and cervical setae, presence/ size/ shape of oesophageal bulb, shape of spicular apparatus and shape of tail. Tabular and pictorial keys were provided based on these characters. Three sympatric species: T. communis, T. gourbaultae, and T. longicaudata were redescribed based on recently collected Cuban specimens. Each of them showed relatively large differences in body size in comparison with the respective type specimens, suggesting possible variation due to local environmental differences. The highest intraspecific variation pertains for the most widely spread cosmopolitan species T. longicaudata, suggesting that morphological plasticity enhanced adaptation to different environmental conditions. The notable taxonomic inflation within the genus (13 species inquirendae, 9 junior synonyms), probably also present in other highly specious genera of marine nematodes, can lead to an overestimation of the alpha-diversity for some taxa

The early life history of the clam Macoma balthica in a high CO₂ world

This study investigated the effects of experimentally manipulated seawater carbonate chemistry on several early life history processes of the Baltic tellin (Macoma balthica), a widely distributed bivalve that plays a critical role in the functioning of many coastal habitats. We demonstrate that ocean acidification significantly depresses fertilization, embryogenesis, larval development and survival during the pelagic phase. Fertilization and the formation of a D-shaped shell during embryogenesis were severely diminished: successful fertilization was reduced by 11% at a 0.6 pH unit decrease from present (pH 8.1) conditions, while hatching success was depressed by 34 and 87%, respectively at a 0.3 and 0.6 pH unit decrease. Under acidified conditions, larvae were still able to develop a shell during the post-embryonic phase, but higher larval mortality rates indicate that fewer larvae may metamorphose and settle in an acidified ocean. The cumulative impact of decreasing seawater pH on fertilization, embryogenesis and survival to the benthic stage is estimated to reduce the number of competent settlers by 38% for a 0.3 pH unit decrease, and by 89% for a 0.6 pH unit decrease from present conditions. Additionally, slower growth rates and a delayed metamorphosis at a smaller size were indicative for larvae developed under acidified conditions. This may further decline the recruit population size due to a longer subjection to perturbations, such as predation, during the pelagic phase. In general, early life history processes were most severely compromised at similar to pH 7.5, which corresponds to seawater undersaturated with respect to aragonite. Since recent models predict a comparable decrease in pH in coastal waters in the near future, this study indicates that future populations of Macoma balthica are likely to decline as a consequence of ongoing ocean acidification