Nodoscarus senisetatus, Kim & Boxshall, 2020

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 643-645

Nodoscarus senisetatus gen. et sp. nov.

( Fig. 437 )

Typematerial. Holotype (intact ♀, MNHN-IU-2009- 5231 ) , paratypes (2 intact ♀♀, MNHN-IU-2014-21460), anddissectedparatype (♀, figured) from Leptoclinides sp., ATIMOVATAE TA 41, southeast of Madagascar (24°50.2 Ś, 47°10.7 É), depth 20 m, MNHN coll., 09 June 2010.

Etymology. The specific name is derived from the Latin seni (=six) and set (=bristle), referring to the presence of six setae on the mandible of the new species.

Descriptionoffemale. Body ( Fig. 437A ) elongate, cylindrical, vermiform, unsegmented, straight, arched or sigmoid. Anterior third of body tapering anteriorly; posterior third of body narrower than mid-region. Body length 4.31 mm in figured, dissected specimen, 4.23 mm in holotype, and 2.88 and 2.90 mm in paratypes: body width 0.49 mm in dissected specimen. Body surface smooth (not wrinkled) in longer specimens, but displaying fine transverse wrinkles in shorter specimens (2 intact paratypes). Body surface ornamented with minute setules; setulation dense anteriorly but sparse in middle and posterior regions. Paired linear ovaries, occupying about half of body length, visible through body wall. Copulatory pore observable on posteroventral surface ( Fig. 437B ). Posterior end of body ( Fig. 437B ) bilobed, with deep median (anal) incision. Caudal rami and caudal setae absent.

Rostrum ( Fig. 437C ) large, longerthanwide, covered with setules over most of ventral surface but naked distally. Antennule ( Fig. 437C, D ) lobate, muchwiderthanlong, densely setulose, armed with about 8 setae, longest seta bluntly tipped, aesthetasc-like. Antenna ( Fig. 437E ) small, stout, 2-segmented; first segment (coxobasis) unarmed, 1.5 timeslongerthan wide; secondsegment (endopod) slightly longerthanwide (14×12 μm), half aslongas coxobasis: armed with 5 small setae distally plus stout terminal claw, 0.6 times as long as endopod, with pointed tip.

Labrum not discernible. Mouthparts positioned within pre-oral cavity; only 2 pairs of mouthparts present. Mandible (first pair, Fig. 437F ) lobate, armedwith 6 small, subequal setae. Maxillule (second pair, Fig. 437G ) lobate, bearing 2 setae at tip. Large, anteriorly-directed, post-oral protuberance present posterior to mouthparts ( Fig. 437C ). Maxillae, maxillipeds, and legs absent.

Male. Unknown.

Remarks. Nodoscarus senisetatus gen. et sp. nov. differs from all of its congeners described above in having only two pairs of mouthparts (mandibles and maxillules). The large rostrum, the stout antenna, and the distinct posteromedian incision of the body are additional features which help to distinguish the new species.

Figures

FIGURE 437. Nodoscarus senisetatus gen. et sp. nov., female. A, habitus, ventral; B, posterior end of body, ventral; C, cephalic region, ventral; D, antennule; E, antenna; F, mandible; G, maxillule. Scale bars: A, 0.5 mm; B, 0.1 mm; C, D, 0.02 mm; E–G, 0.01 mm.