Nobinerilla mammillata, 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 : 285-290

Nobinerilla mammillata gen. et sp. nov.

( Figs. 192 , 193 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21296 ) , paratypes (5 intact ♀♀, MNHN-IU-2-14-21297), and dissected paratypes (2 ♀♀, figured) from Eudistoma amplum (Sluiter, 1909) (MNHN-IT-2008-3949 = MNHN A3/ EUD /84), CRRFOCDN 1174-L, Palau Islands, Venture ML (cave dwelling), depth 1 m, 05 July 1993.

Additionalmaterial. 1♀ (dissected)from E. amplum, OCDN 5053-A, Palau; 1 ♀ (dissected) from Eudistoma sp., Papua New Guinea (10°06.33 Ś, 150°57.68 É), depth 7 m, 20 January 2002.

Etymology. The specific name is derived from the Latin mammill (a teat), alluding to the shape of the posterolateral processes on the cephalosome.

Descriptionoffemale.Body( Fig.192A )compressed, strongly curved, and relatively small (length 1.45 mm). Cephalosome forming small nipple-shaped processes (arrowhead in Fig. 192A ) at posterolateral corners of dorsal shield. Metasomeunsegmented with thin, soft exoskeleton; fifth pedigerous somite incorporated into metasome. Freeurosome ( Fig. 192B ) 5-segmented: genital somite much wider than first abdominal somite. Anal somite with large anal operculum. Caudal ramus ( Fig. 192C ) 3.5 times longer than wide (104×30 μm) and 1.3 times longer than anal somite, slightly narrowing distally: armed with 6 naked setae; outer lateral and dorsal setae located at 50 and 75% of ramus length, respectively; distal largest seta 127 μm long, longerthan ramus; second largest seta 72 μm long.

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; III, I, 4	0-1; 0-1; 1, 2, 2
Leg 2	0-0	1-0	1-1; 1-1; 3, 1, 5	0-1; 0-2; 1, 2, 3
Leg 3	0-1	1-0	1-1; 1-1; 2, 1, 5	0-1; 0-2; 1, 2, 3
Leg 4	0-1	1-0	1-1; 1-1; 2, 1, 5	0-0; 0-1; 1, 2, 2

Rostrum ( Fig. 192D ) widerthan long, strongly tapering and narrowing at mid-length towards angular apex.Antennule( Fig.192E )clearly9-segmented;armature formula 3, 14+spine, 7, 3+aesthetasc, 1, 3, 2+aesthetasc, 5, and 7+aesthetasc; all setae naked. Antenna ( Fig. 192F ) stout, 4-segmented; coxa, basis and first endopodal segment unarmed; compound distal endopodal segment about 1.8 times longer than wide (42×24 μm), as long as first segment; armedwith 7 setae (all attenuated) plus terminal claw, longer than segment.

Labrum ( Fig. 192G ) simple, covered with dense setulesposterolaterally. Mandible ( Fig. 192H ) with 5 teeth and 1 subsidiary tooth between distal first and second teeth on coxal gnathobase ( Fig. 192I ); basis with 1 small seta on medial margin (arrowhead in Fig. 192H ); exopod unsegmented with 5 setae, distalmost seta shorterthan other 4; endopod incompletelyarticulatedfrom basis, with 4 and 7 setae on first and second segments, respectively. Paragnath with 1 short process apically and setules on medial margin. Maxillule ( Fig. 192J ) with 9 setae on arthrite, 1 on coxal endite, 2 on epipodite, 3 on basis, and 4 each on exopod and endopod; exopodal segment broadened, 2 outer setae broad and 2 inner setae much shorter than outer setae. Maxilla ( Fig. 193A ) 5-segmented; syncoxawith 3, 1, 2, and 3 setae on first to fourth endites, respectively; basis with strong claw plus 1 seta; endopod with 1, 1, and 2 setae on first to third segments, respectively. Maxilliped ( Fig. 193B ) 1-segmented and armed with 10 medial setae and 1 outer distal seta; surface ornamented with minute scattered spinules.

Legs 1–4 ( Fig. 193 C-F) with 3-segmented rami. Inner coxal seta absent in legs 1 and 2, present in legs 3 and 4. Inner coxal seta of leg 4 short and naked, absent in some specimens (as in Fig. 193F ). Outer seta on basis large (longer than exopod) in leg 1, butsmall inlegs 2–4. Inner distal spine on basis of leg 1 extending to distal border of firstendopodal segment, 39 μm long. Exopod 1.1 times longer than endopod in leg 1, about 2.4 times longer in leg 2, and 1.9 times longer inlegs 3 and 4. Third exopodal segment inlegs 2–4 elongated, distinctly longerthan first segment. Exopods of legs 2–4 bearing only setae. Distal setae on third exopodal segment of legs 2–4 attenuated in left legs, but short and blunt tipped in right legs (cf. Fig. 193F and G ). Inner seta on first exopodal segment of leg 4 vestigial. Inner setae on endopod of leg 1 very large. First endopodal segment of leg 4 lacking inner seta. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 193H ) 2-segmented. Left and right protopods fused to form wide protopodal plate armed with 1 seta at each outer distal corner, and ornamented with row of minute spinules near base of exopod; exopodal segment stout, about 2.0 timeslongerthan wide (45×22 μm), armed with 1 seta (50 μm long) at outer distal corner and ornamented with 4 rows of minute spinules on inner surface.

Male. Unknown.

Remarks. The nipple-shaped processes at the posterolateral corners of the cephalosome are a diagnostic feature of N. mammillata gen. et sp. nov. Schellenberg (1922) recorded the presence of similar processes in N. armata , but the latter species can be distinguished by having 3 setae on the endopod of the maxillule (cf. 4 in the new species), and in lacking the inner seta on the second exopodal segment of leg 1 (cf. seta present). The possession of 7 setae on the second endopodal segment of the mandible also is a diagnostic feature of the new species when compared to 6 setae in the type species N. alata gen. etsp. nov. and N. armata , and 5 setaein N. filipes and N. exilipes gen. etsp. nov. ( Table 4)

Figures

FIGURE 192. Nobinerilla mammillata gen. et sp. nov., female. A, habitus, right; B, urosome, ventral; C, caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible with seta on basis marked by arrowhead; I, mandibular gnathobase; J, maxillule. Scale bars: A, 0.2 mm; B, 0.1 mm; C, E, H, 0.05 mm; D, F, G, I, J, 0.02 mm.

FIGURE 193. Nobinerilla mammillata gen. et sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, left leg 2; E, left leg 3; F, left leg 4; G, distal segments of right leg 4. Scale bars: A, B, H, 0.02 mm; C, D–G, 0.05 mm.