Prodoroixys bathybia Kim & Boxshall 2020, gen. et sp. nov.

Prodoroixys bathybia gen. et sp. nov.

(Figs. 338, 339)

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21386) from unknown host, BIOGAS 4 DS63, Atlantic, Golfe de Gascogne, “ Jean Charcot ” (47°33’N, 08°35’W), depth 2126 m, IFREMER coll., 26 February 1974.

Etymology. The specific name is derived from the Greek words bath (=deep) and bio (=life), referring to the discovery of the new species in the deep sea (2126 m).

Descriptionoffemale. Body (Fig. 338A) small, not swollen; bodylength 875μm. Prosome675 μmlong:dorsal cephalic shield large, lacking posterolateral processes, but with posterolateral corners produced, nipple-shaped. First to fourth pedigerous somites discernible by 3 dorsal constrictions on metasome; fourth pedigeroussomite containing large eggs inside. Fifth pedigeroussomite not defined. Freeurosome (Fig. 338B) 5-segmented: genital and 4 abdominalsomites 34×120, 47×119, 37×108, 28×94, and 51×81 μm, respectively. Caudal rami directed posteriorly, gently narrowing distally; each ramus (Fig. 338C) about 4.2 times longer than wide (83×20 μm), and ornamented with thin setules mainly on outer surface: armedwith 6 setae (outer lateral, dorsal, and 4 subdistal), outer distal and dorsal setae positioned at 36 and 45% of ramus length; all setae naked and shorter than width of ramus at base.

Rostrum (Fig. 338D) large, 70×44 μm, tapering evenly towards blunt apex. Antennule (Fig. 338E) 130 μmlong, 9-segmented; armatureformula 2, 13, 6, 5, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc. Antenna (Fig. 338F) stout, 4-segmented; proximal 3 segments unarmed; terminal segment about 2.5 times longerthan wide (37×15 μm) and as long as first endopodal segment: armedwith 8 setae (arranged as 1, 2, 2, and 3) plus terminal claw more than half length of segment.

Labrum (Fig. 338G) withsetulose posteriormarginand posteromedial lobe. Mandible (Fig. 338H) with broadened coxal gnathobasebearing 5 teeth and1 small seta: basiswith 1 setaonmedial margin: exopodwith 5 large, equal setae: endopod with 1 and 5 setae on first and second segments, respectively. Paragnath (Fig. 338I) assmalllobe bearing 1 denticle apically and setules on medial margin. Maxillule (Fig. 338J) armedwith 9 setae on arthrite, 1 each on coxal endite and epipodite, 2 on basis, 4 on exopod, and 3 on endopod. Maxilla (Fig. 338K) 5-segmented; syncoxawith 3, 1, 2, and 3 setaeon first to fourth endites, respectively; basis with smooth claw plus 2 setae; endopod with 1, 1, and 4 naked setae on first to third segments, respectively. Maxilliped (Fig. 339A) unsegmented, armedwith 10 setae (8 medial and 2 apical).

Legs 1–4 biramous with distinctly 3-segmented rami (Fig. 339 B-D). Innercoxalsetaabsentinlegs 1– 4. Exopodal segments of legs 1–3 bearing outer spines, but exopod of leg 4 with bluntly tipped setae. Armature formula for legs 1–4 as follows:

Leg 5 (Fig. 338B) represented by 2 indistinct lobes of posteroventral margin of somite; inner exopodal lobe tipped with 2 setae and outer protopodal lobe with 1 seta.

Male. Unknown.

Remarks. The major differences between Prodoroixys bathybia gen. et sp. nov. and P. antarctica gen. et sp. nov. are the more slender caudal rami in the former, the presence of 5 setae on the second endopodal segment of the mandible (cf. 6 or 7 in the type species), 4 setae on the third endopodal segment of the maxilla (cf. 3 in the type species), 10 setae on the maxilliped (cf. 6 to 9 setae in the type species), the absence of an inner coxal seta on leg 1 (cf. present in the type species), and the different armature states of the posterior swimming legs.