Prodoroixys bathybia, 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 : 510

Prodoroixys bathybia gen. et sp. nov.

( Figs. 338 , 339 )

Coxa Basis Exopod Endopod
Leg 1	0-0	1-I	I-1; I-1; III, 1, 4 0-1; 0-1; 1, 2, 2
Legs 2 & 30-0		1-0	I-1; I-1; III, I, 5	0-1; 0-1; 1, 2, 2
Leg 4	0-0	1-0	1-1; 1-1; 2, 1, 5	0-1; 0-1; 0, 2, 2

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.

Figures

FIGURE 338. Prodoroixys bathybia gen. et sp. nov., female. A, habitus, right; B, leg 5 and urosome, ventral; C, left caudal ramus, ventral; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, paragnath; J, maxillule; K, maxilla. Scale bars: A, 0.1 mm; B, 0.05 mm; C–K, 0.02 mm.

FIGURE 339. Prodoroixys bathybia gen. et sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 4. Scale bars: 0.02 mm.