Nobinerilla paucisetata, 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 : 296-299

Nobinerilla paucisetata gen. et sp. nov.

( Figs. 198 , 199 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21302 ) anddissectedparatype (♀, figured) from Aplidium nadaense (Nishikawa, 1980) (MNHN-IT-2008-576 = MNHNA 1 / APL.B/407), Brooker Channel, Calvados Island Chain, Louisiade Archipelago, Papua New Guinea (11°03.09’S, 152°28.62’E), depth 7 m, 01 June1999.

Additionalmaterial. 3 ♀♀ (MNHN-IU-2018-1845) and 1 dissected ♀ from Aplidium californicum (Ritter & Forsyth, 1917) , New Caledonia UA 33.

Etymology. The specific name is a combination of the Latin pauci (=few) and seta (=bristle), referring to the low number of setae on the third endopodal segment of leg 4.

Descriptionoffemale.Body( Fig.198A )compressed, 1.36 mm long. Cephalosome well defined from metasome. Metasome elongate, unsegmented, with very thin, soft exoskeleton and 2 pairs of lateral epimeral wings: both slightly incurved, with claw-like posterodistal process ornamented with membranous fringe along dorsal margin ( Fig. 198B, C ). Freeurosome ( Fig. 198D ) 5-segmented: genitalsomite 36×140 μm; 4 abdominalsomites 56×109, 40×109, 33×104, and 55×102 μm, respectively: lateral margins of abdomen more-or-less parallel. Caudal rami ( Fig. 198E ) widely separated from each other, about 2.8 times longer than wide (65×23 μm): armed with 6 naked setae; outer lateral and dorsal setae located at 46 and 68% of ramus length, respectively; longest and second longest setae 136 and 75 μm long, both longer than ramus.

Rostrum ( Fig. 198F ) much widerthan long, steeply tapering. Antennule ( Fig. 198G ) 195 μm long, 9-segmented; second segment partially subdivided proximally by line of unsclerotized cuticle; armature formula 3, 16, 6, 3, 1, 3, 2+aesthetasc, 4+aesthetasc, and 7+aesthetasc; aesthetascs on seventh and eighth segments very small. Antenna ( Fig. 198H ) 4-segmented; coxa and basis unarmed; first endopodal segment with 1 setaon inner margin; compound distal endopodal segment about 2.1 times longerthan wide (36×17 μm) and as long as first segment; armed with 7 setae plus large and strongly curved terminal claw, longer than segment.

Labrum ( Fig. 198I ) with large, linguiform posteromedianlobe and ornamented with minutesetules on both sides of posterior margin. Mandible ( Fig. 198J ) with 4 teeth on coxal gnathobase; basis with 1 small, naked setaon medial margin; exopod with 5 setae, outer distal seta shorter than other 4; endopod indistinctly articulated from basis, with 4 and 6 setae on first and second segments, respectively. Maxillule ( Fig. 198K ) armed as in N. minuta gen. et sp. nov. Maxilla ( Fig. 198L ) 5-segmented; syncoxawith 9 setae, including 3 setae on first endite; basis with slender claw plus 1 seta; endopod with 1, 1, and 2 setae on first to third segments, respectively. Maxilliped ( Fig. 199A ) unsegmented with 10 medial setae and 1 outer distal seta.

Legs 1–4 ( Fig. 199 B-F) with 3-segmented rami. Inner coxal seta present in leg 3, absent in legs 1, 2, and 4. Outer seta on basis large (longer than exopod) in leg 1, small in legs 2–4. Innerdistalspineonbasisofleg 1 extending beyond distal border of first endopodal segment, 30 μm long, with spinulose margins. Exopod of leg 1 slightly longer than endopod. In legs 2–4 both rami of right legs broader than those of left legs (cf. Fig. 199C and D ). In left legs 2–4, exopod 1.8 timeslongerthan endopod in legs 2 and 3, and 1.9 times longer in leg 4. Distal setae on third exopodal segment of legs 2–4 attenuated in left legs but blunt at tip and shortened in right legs. Armature formula for legs 1–4 as follows:

Figures

FIGURE 198. Nobinerilla paucisetata gen. et sp. nov., female. A, habitus, right; B, distal part of anterior metasomal wing; C, distal part of posterior metasomal wing; D, urosome, ventral; E, caudal ramus, dorsal; F, rostrum; G, antennule; H, antenna; I, labrum; J, mandible; K, maxillule; L, maxilla. Scale bars: A, 0.1 mm; B, C, E–L, 0.02 mm; D, 0.05 mm.

FIGURE 199. Nobinerilla paucisetata gen. et sp. nov., female. A, maxilliped; B, leg 1; C, left leg 2; D, right leg 2; E, left leg 3; F, left leg 4; G, left and right legs 5. Scale bars: A, 0.02 mm; B–G, 0.05 mm.