Notodelphys cuspis sp. nov.

(Figs. 26–28)

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21216), allotype (intact ♂, MNHN-IU-2014-21217), paratypes (intact, 5 ♀♀, 1 ♂, MNHN-IU-2014-21218), and dissected paratypes (1♀, 1 ♂; figured) from Molgula occulta Kupffer, 1875 (MNHN-IT-2008-5629 = MNHN S3/ MOL.A/42), Dakar, Senegal, Stn 58-4-2B (depth 43– 44 m) & 58-2-19B (depth 12 m), IFAN coll., 1966–1969.

Etymology. Thename isderived from the Latin cuspi (= a point), referring to the tooth-like, spinous process on the inner distalcorner of the basis of leg 1.

Descriptionoffemale. Body (Fig. 26A) 2.76 mm long. Prosome consisting of cephalosome and first to third free pedigerous somites, with fourth pedigerous somite forming inflated brood pouch. Fifth pedigerous somite fused to thin-walled brood pouch. Free urosome (Fig. 26B) 5-segmented, consistingof genital and 4 abdominal somites: dimensions 127×233, 196×236, 211×215, 160×191, and 127×164 μm, respectively. Anal somite distinctly narrower than preceding somites. Caudal ramus (Fig. 26C) about 2.9 timeslongerthan wide (145×50 μm) and 1.14 times longer than anal somite, densely setulose along outerand inner margins, armedwith 6 pinnate setae; outer lateral seta positioned at 58% of ramus length.

Rostrum (Fig. 26D) 150×144 μm, tapering from broad basal region to rounded apex. Antennule (Fig. 26E) 360 μm long and 15-segmented; articulation between second (III-V) and third (VI-XI) segments incomplete; armatureformula 3, 5, 12, 4, 4+aesthetasc, 2, 2, 2, 1, 2, 1, 1, 2, 2+aesthetasc, and 7+aesthetasc; 3 setae (2 on first and 1 on second segment) pinnate, all other setae naked (as figured); setaon ninth (derived from segment XX) and twelfth segments (derived from XXIII) annulated at base. Antenna (Fig. 26F) 4-segmented; coxashortand unarmed; basis with 2 outer pinnate setae representing exopod (shorter seta about 65% length of longer one); first endopodal segment with 1 seta on inner margin; compound distal endopodal segment about 3.8 times as long as wide (121×32 μm), armed with terminal claw and 10 setae (arranged as 1, 1, 3, 2, and 3 from proximal to distal) and ornamented with 3 rows of spinules on outer surface; terminal claw small, about one-third length of segment; 3 distalsetae bluntly tipped.

Labrum (Fig. 26G) setulose along posterior margin, with protruding posterolateral corners and convex, spinulose mid-posterior lobe. Mandible (Fig. 26H) with 5 pointed teeth and 2 setae on coxal gnathobase; basis with 1 seta on medial margin; exopod unsegmented with 5 setae, distalmost seta markedly larger than others; endopod indistinctly defined from basis, armed with 4 and 9 setae on first and second segments, respectively. Paragnath (Fig. 27I) lobate, with denticle apically and setules on medial margin. Maxillule (Fig. 26J) armedwith 10 setae on arthrite, 1 on coxal endite, 2 on epipodite, 3 (proximal setamuch smaller than distal 2) on medial margin of basis, 4 on exopod; endopodindistinctly 2-segmented, with 1 setaon first segment and 4 on second segment; longest distal seta on second segment naked, outer seta broad proximally. Maxilla (Fig. 27A) 5-segmented; syncoxa with 9 setae, grouped as 3 + minute seta, 1, 2, and 3 on first to fourth endites; basis with strong curved claw and 1 seta; endopod slender, with 1, 1, and 3 setaeonfirst to third segments, respectively. Maxilliped (Fig. 27B) 3- segmented; first segment armed with 10 setae, 2 of which shorter and broader; second segment with 1 spiniform seta; third segment narrow and armed 1 large spiniform seta and 1 small naked seta.

Legs 1–4 with 3-segmented rami. Outer setaon basis short and naked in all legs (Fig. 27C, E, F). Leg 1 basis broad with projecting inner distal corner tipped with denticle originating internally (Fig. 27C, D) plus small, naked inner distal seta (not spine); third exopodal segment armed with 3 spines and 5 setae (terminal spine transformed to slightly curved seta); first endopodal segment as long as wide, not elongated. Legs 2–4 exopods armed only with setae; all outer setae naked. Armature formula for legs 1–4 as follows:

Leg 5 (Fig. 27G) protopod fused to brood pouch, not articulated at base, with blunt outer process tipped with pinnate seta; free exopodal segment quadrate (28×28 μm) with minute, rudimentary inner subdistal seta and naked distal seta; no spinules present on protopod or exopod.

Descriptionofmale. Body (Fig. 28A) narrow, 1.48 mm long. Cephalosome 316×464 μm, distinctly broader than following somites. First pedigerous somite slightly narrower than second pedigerous somite. Urosome 6- segmented, cylindrical, ventrally curved posteriorly. Anal somite ornamented with row of small spinules along posteroventral border (Fig. 28B). Caudal ramus (Fig. 28B) about 3.1 times longerthan wide, withsmall spinules distally and subdistally on ventral surface; setules sparse on outer and inner margins.

Rostrum as in female. Antennule (Fig. 28C) 10- segmented and geniculate between eighth and ninth segments; second segment with trace of articulation proximally; armatureformula 3, 17, 2, 2, 2, 4+aesthetasc, 2, 2, 1+aesthetasc, and 10+aesthetasc; eighth and ninth segments each with fused setal element forming dentiform process on anterior margin.Antenna, mouthparts, and legs 1–4, including basis of leg 1, as in female.

Leg 5 (Fig. 28D) similartothatof female. Leg 6 (Fig. 28D) represented by 2 naked setae of unequal length on distal margin of genital operculum.

Remarks. This species is characterised by two unique features. The third segment of the maxilliped is armed only with 2 setae, whereas the great majority of Notodelphys species carry 3 setae on thethird segment of the maxilliped. The only exceptions are N. weberi and N. cuspis sp. nov., with the former carrying 4 setae on this segment and the latter only 2 setae. In the new species, the basis of leg 1 is armed with a small seta instead of a spine, and a small spinous process is present at the inner distal angle: such a configuration is unknown elsewhere in the genus.