Nobinerilla minuta Kim & Boxshall 2020, gen. et sp. nov.

Nobinerilla minuta gen. et sp. nov.

(Figs. 196, 197)

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21300), paratypes (2 intact ♀♀, MNHN-IU-2014- 21301), anddissectedparatype (♀, figured) from Pseudodistoma poculum Monniot F. & Monniot C., 1996 (Holotype MNHN-IT-2008-7380 = MNHNA 1/ PSE /28), OCDN 0104- V, Kuop Atoll, Chuuk State, Micronesia (07°00.00’N, 151°56.05’E), depth 30 m, 01 June 1992.

Etymology. The name is derived from the Latin minut (=small), referring to the small body of the new species.

Descriptionoffemale. Body (Fig. 196A) small, 0.70 mmlong. Cephalosomewell-definedfrom metasome, with angular posterolateral corners. Metasome unsegmented, slightly swollen dorsally, with thin, soft exoskeleton and 2 pairs of lateral wings: each wing forming pointed posterolateral process ornamented with membranous fringe along dorsal margin. Free urosome (Fig. 196B) 5- segmented; 4 abdominalsomites 35×88, 29×75, 26×72, and 35×69 μm, respectively. Anal operculum large. Caudal ramus (Fig. 196C) tapering, 2.05 times longer than wide (39×19 μm): armed with 6 naked setae; longest and second longest setae 56 and 33 μm long; outer lateral and dorsal setae located at 57 and 77% of ramus length, respectively.

Rostrum (Fig. 196D) short, muchwiderthanlong, apical part distinctly narrower. Antennule (Fig. 196E) 125 μmlong, 9-segmented; armatureformula 3, 16, 6, 4, 1, 3, 2+aesthetasc, 4+aesthetasc, and 7+aesthetasc; eighth segment with incomplete subdivision in middle; all setae naked. Antenna (Fig. 196F) 4-segmented; coxa and basis unarmed; first endopodal segment with 1 seta on inner margin; compound distal endopodal segment slightly longer than first and about 1.9 times longerthan wide (25×13 μm); armed with 7 setae plus relatively large, strongly curved terminal claw, slightly longer than segment.

Labrum (Fig. 196G) with large, setulose posteromedianlobe. Mandible (Fig. 196H) with 5 teeth on coxal gnathobase; basis with rudimentary medial seta; exopodwith 5 subequal setae; endopodwith 4 and 6 setae on first and second segments, respectively. Maxillule (Fig. 196I) asin N. ovata gen. etsp. nov. Maxilla (Fig. 196J) 5-segmented; syncoxawith 8 setae, first endite characteristically with only 2 setae; basis with clawplus 1 seta; endopodwith 1, 1, and 2 setaeonfirst to third segments, respectively. Maxilliped (Fig. 197A) unsegmented with 8 (4+4) medial setae plus 1 outer distal seta.

Legs 1–4 (Fig. 197 B-E) with 3-segmented rami. Inner coxal seta present in leg 3, absent in legs 1, 2, and 4. Outer seta on basis large, plumose, as long as exopod in leg 1, smaller and naked in legs 2–4. Exopod subequal in length to endopod in leg 1, 1.8 times longer in leg 2, and 1.5 times longer in legs 3 and 4. All setae on exopods of right legs 2–4 blunt at tip and shorter than those of left legs. Second endopodal segment of right leg 4 bearing inner seta (Fig. 197F) but seta absent in left leg 4 (Fig. 197E). Armature formula for legs 1–4 as follows:

Leg 5 (Fig. 196B) consistingof 1 setaon protopod incorporated into somite, plus free exopod; exopodal segment (Fig. 197G) small, about 2.7 timeslongerthan wide (24×9 μm), with 1 outerdistalseta (25 μmlong) and 4 rows of spinules on inner surface.

Male. Unknown.

Remarks. Nobinerilla minuta gen. et sp. nov. is similar to the type species N. alata gen. et sp. nov. in several respects. They both have a 9-segmented antennule, 6 setae on the second endopodal segment of the mandible, and 9 setae (8 medial and 1 outer distal) on the maxilliped. However, the shape of the exopod of leg 5 is quite different: it is about 2.7 times longer than wide and ornamented with spinule rows in N. minuta gen. et sp. nov. but about 3.5 times longer than wide and naked (without spinule rows) in N. alata gen. et sp. nov. The most striking feature of the setation of N. minuta gen. et sp. nov. is the possession of only 2 setae on the first endite of the syncoxa of the maxilla. This characteristic serves to distinguish the new species from all congeneric species.