The genus Cletocamptus (Harpacticoida, Canthocamptidae): a reappraisal, with proposal of a new subfamily, a new genus, and a new species

A new species of Cletocamptus closely related to C. helobius was found in sediment samples taken from a polluted estuarine system in north-western Mexico. The genus Cletocamptus was relegated to species incertae sedis in 1986, and this finding prompted us to evaluate the current taxonomic position of the genus within the Canthocamptidae. The latter has been subdivided in several, seemingly unnatural subfamilies in the past to better understand the relationships between its constituent taxa. In this study we propose a new subfamily, the Cletocamptinaesubfam. nov. for Amphibiperita, Cletocamptus, and Cletocamptoides gen. nov., defined by the synapomorphic subdistal ventral spinules on the rostrum. The genus Cletocamptoidesgen. nov. is proposed for C. helobius, C. merbokensis, and C. biushelosp. nov., and is supported by the ‘cletodid’ shape of the body and the reduced one-segmented endopod of the fourth swimming leg. Cletocamptus includes all the other species with long slender spinules on the posterior margin of prosomites and with the sexually modified inner spine on the second endopodal segment of the second swimming leg in the males. Amphibiperita retained the primitive female fifth leg with exopod and baseoendopod separated, and the primitive prehensile endopod of the first leg, but is defined by the loss of the antennary exopod. Other (syn)apomorphies are given, and the evolution of the mandibular palp is briefly discussed. Additionally, a diagnosis for the new subfamily, Cletocamptinaesubfam. nov., an amended narrower diagnosis for Cletocamptus, the diagnosis for Cletocamptoidesgen. nov., and a phylogenetic analysis supporting the proposal of these new taxa, are given.

­On two new species of Nannopus Brady, 1880 (Copepoda: Harpacticoida: Nannopodidae) from intertidal mudflats of the Korean west coast (Yellow Sea)

Two new species in the genus Nannopus Brady, 1880 (Copepoda: Harpacticoida) from intertidal mudflats of the Yellow Sea along the Korean peninsula, Nannopus cylindricus sp. nov. and N. robustus sp. nov., are described. Nannopus cylindricus belongs to the group of Nannopus species with seven elements on P4 exp-3. Within this group, it is closest to a cryptic species complex related to N. ganghwaensis Vakati, Kihara & Lee, 2016 based on an inflated caudal seta IV. However, N. cylindricus differs from the other species in this complex with respect to caudal seta V (inflated and heavily cylindrical at its base in N. cylindricus, inflated only in the N. ganghwaensis cryptic complex). Nannopus robustus belongs to the group of species displaying two setae on P2 enp-2. Within this group, N. robustus is closely related to N. serratus Vakati & Lee, 2017 based on the presence of one endopodal naked seta arising from a stem-like protrusion on the mandibular palp. However, N. robustus can be distinguished from N. serratus based on the following characters: outermost distal spine on P2 exp-3 (extremely strong, smooth and recurved in N. robustus, moderately strong, denticulate and normal-shaped in N. serratus, and spine 1.6 times as long in N. robustus as in N. serratus), P2 exp-2 inner seta (absent in N. robustus, present in N. serratus), shape of caudal seta V (anterior part distinctly cylindrical in N. robustus, normal-shaped in N. serratus), and ornamentation of caudal seta VI (naked in N. robustus, pinnate in N. serratus). An updated key to the 17 valid species of Nannopus is provided.

A new species of Hangangbathynella (Crustacea, Bathynellacea, Parabathynellidae) from South Korea

A new parabathynellid bathynellacean species, Hangangbathynella mihoensissp. nov., was found in the groundwater of the Geumgang River in South Korea. This is the first report of Hangangbathynella from a tributary of the Geumgang River. All previously-reported species were found in the Hangang River and the origins of the two rivers are distinct from each other. The new species can be distinguished from its congeners by the two-segmented mandibular palp and the absence of epipods on thoracopod II. In this study, we provide a description of the new species and an identification table for the genus Hangangbathynella. In addition, we obtained partial sequences of the mitochondrial cytochrome c oxidase subunit I gene for DNA barcoding.

New species of Sargassum-boring Limnoria Leach, 1814 (Crustacea, Isopoda, Limnoriidae) from Japan

A new marine Sargassum-boring species of Limnoria (Limnoriidae) is described on the basis of specimens obtained at Kamogawa-shi, Chiba Prefecture, Japan. Limnoria aspera sp. nov. shares a reduced mandibular palp to a seta, algal-feeding, and the clavate shaped epipod of the maxilliped with the other species of non-mandibular-palp group. L. aspera sp. nov. differs morphologically from the congeneric species by secondary unguis of pereopods and unique carinae of pleonite 5 and pleotelson. We describe the sequences of the mitochondrial COI gene and the nuclear 28S rDNA gene. L. aspera sp. nov. differs by 14.2–18.0% in p-distance based on COI sequences from other Japanese species, L. furca and L. nagatai.

Leptostracans (Crustacea: Phyllocarida) from mud volcanoes at the Gulf of Cadiz (NE Atlantic) with description of a new species of Sarsinebalia Dahl, 1985

Three leptostracan species (Crustacea: Phyllocarida) are reported from mud volcanoes at the Moroccan margin of the Gulf of Cadiz (NE Atlantic). Nebalia strausi Risso, 1826 and N. abyssicola Fage, 1929 were found in experimentally deployed organic substrates in Mercator, Meknès and Darwin mud volcanoes; N. abyssicola was also found among bathymodiolin bivalves and is recorded for the first time in the Atlantic Ocean. The third species was collected from the Gemini mud volcanoes and is described herein as Sarsinebalia ledoyeri sp. nov. The new species is characterised by having the eyes provided with ommatidia and lacking pigment, the ventral margin of the eye is concave along distal half, the antennular scale is more than twice as long as wide, the second article of the mandibular palp bears one seta on lateral surface about 0.5 times as long as the article and one subterminal seta longer than the third article, the distal article of the maxilla II endopod is about 1.8 times as long as the proximal article, the maxilla II exopod is clearly longer than the endopod proximal article, the lateral margin of the pleopod I exopod lacks setae and the posterodorsal border of pleonites VI–VII is provided with rounded to pointed denticles.

A New Species of Freshwater Amphipods Echinogammarus (Amphipoda, Gammaridae) from Algeria

Several samples of amphipods were obtained from six stations in the upper reach of the Youkous Stream, near Hammamet. This study describes a new species, Echinogammarus monodi n.sp., differing from other Echinogammarus species in the length of the first antenna, the setation of the third article of the mandibular palp (bearing three rows of A-setae and two rows of B-setae), the merus and carpus of pereopods 5 with long setae only, and the exopodite of uropod 3 with numerous groups of long simple setae. A full description of the new species and information about its distribution is given in this paper.

Species of the Maera-clade collected from Japan. Part 4: addenda to genera Maera Leach, 1814 and Quadrimaera Krapp-Schickel & Ruffo, 2000, with revised keys to Japanese species of the clade (Crustacea: Amphipoda: Maeridae)

Two new species of Maera Leach, 1814 and Quadrimaera Krapp-Schickel & Ruffo, 2000 included in the Maera-clade are described from Japan. Maera denticoxa sp. nov. was collected from Iwate and Hokkaido Prefectures and can be distinguished from its congeners by the small notches on the posteroventral margins of coxae 1–6. Quadrimaera angulata sp. nov. from north of Tanegashima Island in Kagoshima Prefecture is characterized by the distal tooth on the mandibular palp article 1, the rounded palm of the female gnathopod 2, and the angular posterodistal margin of the pereopod 7 basis. Keys to Japanese species of the Maera-clade are provided. In total, seventeen species included in the clade occur in Japan.

A New Deep-Sea Enhydrosoma (Copepoda, Harpacticoida, Cletodidae) from the Northern Gulf of Mexico

Enhydrosoma texana sp. nov. is described from the northern Gulf of Mexico. The new species is closely related to E. parapropinquum Gómez, 2003 from northwestern Mexico. Both species share several characters including an elongated cylindrical caudal ramus, an abexopodal seta of antennae, the structure of mouthpart appendages, seta formula of thoracic legs P1–P4, the shape of the P5 exopod in the female and the apophysis structure of P3 in males. However, the new species is distinguishable from E. parapropinquum by the shape of the rostrum, number of the antennular segments, the shape of the mandibular palp, the relative lengths of the thoracic legs, the shape of the apophysis of P3 in the male, setal number and length of the P5 exopod of the female, the length of the seta on P5 in the male and the relative lengths of the caudal ramus in both sexes. This is the deepest record of a species in the genus Enhydrosoma.

First record of the genus Boholina (Copepoda, Calanoida, Pseudocyclopidae) in Vietnam, with description of a new species from an anchialine cave in Tra Ban Island

A new species, Boholina reductasp. nov., was found in a brackish pool within an anchialine cave in Tra Ban Island in Bai Tu Long Bay, north Vietnam. The new species is clearly distinguished from all the six species currently known in the genus Boholina by the following unique characteristics: reduction of the septum between gonopores; narrow and pointed rostrum; basal segment of mandibular palp armed with three setae; maxillule without seta on the basal exite, and exopod with 11 setae; second and third endopodal segments of the maxilliped bearing three setae each; exopod of male right leg 5 2-segmented, with two strong and one vestigial spines on the outer margin of the distal segment; and last exopodal segment of female leg 5 bearing only one spine on the outer margin. We provide a description of the new species, along with detailed illustrations and scanning electron microscopy photographs. The identification key to Boholina species is updated as well. This is the first record of the genus Boholina from Vietnam.

A new species of Maraenobiotus (Copepoda, Harpacticoida) from Lena River Delta (North-Eastern Siberia)

A new species of harpacticoid copepod of the family Canthocamptidae, Maraenobiotus supermario sp. nov. is described. The new species was found in interstitial waters of the moss tundra of the Lena River Delta, Siberia. This species belongs to the vejdovskyi-species group. The new species differs from its congeners in the apical caudal setae lacking a bulbous proximal part, and in the unique structure of the mandibular palp with only one seta. We also present detailed figures and description of sensilla and pores on the somites surface, which could be used in the future to diagnose and solve taxonomic issues of this complex genus.