Nodoscarus compressus, 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 : 642

Nodoscarus compressus gen. et sp. nov.

( Fig. 436 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21459 ) from Leptoclinides sp. (MNHN-IT-2008-4861 = MNHNA2/LEP/111), CRRF CRCHO 561, Baluan I., Papua New Guinea (2°32.27’S, 147°17.97’E), open reef, depth 24 m, L. Martin coll., 22 June 2003.

Etymology. The name of the new species refers to its laterally compressed body.

Descriptionoffemale. Body ( Fig. 436A ) vermiform, slightly compressed laterally, smooth, almost straight, unsegmented. Bodylength 6.07 mm; dorsoventraldepth of body 0.98 mm in middle. Both anterior and posterior regions of body narrowing; anterior region slightly curved ventrally; posterior end of body ( Fig. 436B ) weakly incised. No caudal rami or caudal setae present.

Rostrum ( Fig. 436C ) lobate, setulose. Antennule ( Fig. 436C, D ) also lobate, muchwiderthanlong, surface ornamented with numerous fine setules, armed with 5 or 6 small setae at anterodistal corner (1 short, blunt and aesthetasc-like). Antenna ( Fig. 436E ) stout, 2-segmented; first segment (coxobasis) unarmed; second segment (endopod) about 1.5 timeslongerthan wide (22×15 μm), about half as long as coxobasis: armed with 6 smallsetae (arranged as 2, 2, and 2) plus short, stout terminal claw, about half as long as endopod. Antenna, labrum, and first and second mouthparts positioned in indented pre-oral cavity.

Labrum ( Fig. 436C ) large, unornamented, constricted at proximal third, gradually broadening in distal twothirds, with almost straight posterior margin. Three pairs of mouthparts retained ( Fig. 436C ). Mandible ( Fig. 436F ) as unsegmented, digitiform lobe tipped with 1 naked seta. Maxillule ( Fig. 436G ) as stout lobe, bearing 6 naked setae (2 subdistal and 4 distal). Maxilla (third mouthpart, Fig. 436H ) positioned just posterior to pre-oral cavity ( Fig. 436C ), as small lobe tipped with 2 subequal, naked setae. Post-oral swelling present between third pair of mouthparts ( Fig. 436C ), directed anteriorly, covering posterior part of labrum, with rounded margin. Maxillipeds and legs absent

Male. Unknown.

Remarks. The unique numbers of setae on the mandible, maxillule, and maxilla, which are 1, 6, and 2, respectively, allow N. compressus gen. etsp. nov. to be readily differentiated from its congeners. The slightly compressed body of the new species is also an unusual and characteristic feature of N. compressus gen. et sp. nov.

Figures

FIGURE 436. Nodoscarus compressus gen. et sp. nov., female. A, habitus, right; B, posterior end of body, ventral; C, cephalic region, ventral; D, antennule; E, antenna; F, mandible; G, maxillule; H, maxilla. Scale bars: A, 0.5 mm; B, 0.1 mm; C, 0.05 mm; D, E, 0.02 mm; F–H, 0.01 mm.