Oshoroclausia shibazakii, Uyeno & Kakui, 2015

Uyeno, Daisuke & Kakui, Keiichi, 2015, The First Record of a Species of Clausiidae (Copepoda: Cyclopoida) from Japanese Waters, with the Proposal of a New Genus, Species Diversity 20, pp. 153-158 : 154-157

Oshoroclausia shibazakii n. sp.

( Figs 1–3 )

Type material. Holotype female ( NSMT –Cr 24117) from sandy bottom off Oshoro Marine Station (43°12′33.30″N, 140°51′31.10″E), Oshoro Bay, Hokkaido, an inlet of the Sea of Japan, 1 m depth, 30 October 2013, leg. K. Kakui.

Description of adult female. Body ( Fig. 1A, B ) elongate, cylindrical, 5114 long comprising cephalothorax and indistinctly segmented post-cephalothoracic trunk. Cephalothorax longer than wide, 548×387, with projecting rostral area ( Fig. 1C ) bearing triangular ventral margin and pair of sensory elements ( Fig. 1D ). Segmentation of second to fifth pedigers, genital complex, and 3-segmented abdomen indistinct. Genital complex 509 at widest point, with paired lateral lobes ( Figs 1A, B , 2L). Caudal rami longer than wide 111×54, fused at base to anal somite, bearing one medial, one subterminal, and three small and one long distal setae; all setae naked.

Antennule ( Fig. 1F ) 3-segmented; proximal segment bearing two lobes; armature formula: 13, 6+1 aesthetasc, 7+1 aesthetasc; all setae naked. Antenna ( Fig. 1G ) 2-segmented; basal segment unarmed; terminal segment peanutshaped with median crease ( Fig. 1H ); proximal part covered with fine spinules and distal part bearing rounded protruding lobe covered with fine spinules, three small elements, and small, knob-like distal projection ( Fig. 1I ) armed with two serrate spines and two simple setae. Labrum ( Fig. 2A) triangular, bearing pointed conical posterocentral projection and ornamented with paired patches of fine spinules in basal region. Mandible ( Fig. 2B) rod-like, with distal pointed spine. Paragnath ( Fig. 2C) rounded, with horizontal concavity, surface covered with hairs. Maxillule ( Fig. 2D) with one medial and two distal setae. Maxilla ( Fig. 2E) 2-segmented; proximal segment (syncoxa) robust and unarmed; distal segment (basis) bifurcate, bearing patches of fine spinules on each tip and single blunt element on posterior margin. Maxilliped ( Fig. 2F) unsegmented, subdivided into large conical basal part with row of spinules on anterior margin and small, claw-like distal part.

Legs 1 to 4 ( Fig. 2G–J) biramous with 2-segmented rami; armature formula of legs shown in Table 1. All setae naked. Both rami of legs 1 and 2 and exopod of legs 3 and 4 bearing row of fine setules on outer margin. Intercoxal sclerites of legs 3 and 4 absent. Leg 5 ( Fig. 2K) 2-segmented; proximal segment (protopod) fused to pedigerous somite armed with single distal seta; terminal segment (exopod) rod-like, bearing three minute setae on posterior margin and conical tip with basal membranous crescent and apical seta. Leg 6 ( Fig. 2L) represented by two simple setae at base of lateral lobe of genital complex.

Coloration in life. Dull red ( Fig. 3A, B ).

Adult male. Unknown.

Host and habitat. The copepod was found in sediment on a sandy bottom. The host is unknown.

Etymology. The specific name of the new species, shibazakii , was chosen in honor of Mr. Koji Shibazaki, the administrator of the Oshoro Marine Station, Hokkaido University, as a tribute to his constant, devoted support for the many researchers who undertaken fieldwork there.

Newly established Japanese name for the family, the genus and the species. Gokai-mijinko.

Figures

Fig. 1. Oshoroclausia shibazakii n. g. n. sp., holotype, adult female, NSMT–Cr 24117. A, habitus, dorsal; B, habitus, lateral; C, anterior part of cephalothorax, dorsal; D, anterior part of cephalothorax, ventral; E, left caudal ramus, ventral; F, left antennule, anterior; G, right antenna, anterior; H, terminal segment of right antenna, posterior; I, distal part of right antenna, posterior. Scale bars: A, B, 1000µm; C, 100µm; D–F, 50µm; G, 30µm; H, 20µm; I, 10µm.

Fig. 3. Coloration of live specimen of Oshoroclausia shibazakii n. g. n. sp., holotype, adult female, NSMT–Cr 24117. A, habitus straight, dorsal; B, habitus curved, ventrolateral. Scale bar: 500µm.