Enteropsis obtusa, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, Zootaxa 1, pp. 1-286 : 273-275

Enteropsis obtusa sp. nov.

( Fig. 181 )

Type material. Holotype ♀ (MNHN-IU-2014-21584), 5 ♀♀ paratypes (MNHN-IU-2014-21585), and 1 ♀ paratype (dissected, MNHN-IU-2014-17399) from aẚstaplẚa cçrçlla Monniot F., 1974 (MNHN-IT-2008-3694 = MNHN A3 / DIS/35 ); Guadeloupe, Baille Argent face Nord, Stn 83-20, depth 1-3 m, Monniot coll., 04 April 1983.

Etymology. The name of the new species is derived from the Latin çbtus (=blunt), referring to the blunt posterior end of body.

Description of female. Body ( Fig. 181A, B ) eruciform, stout, indistinctly 6-segmented, consisting of cephalosome, first to fourth pedigerous somites, and genitoabdomen. Mean body length 1.0 mm (0.78-1.17 mm, n=7); dissected specimen 1.17 mm; maximum width 393 μm (across third pedigerous somite). Cephalosome ( Fig. 181C ) narrowing anteriorly, with rounded anterior margin; first to fourth pedigerous somites lacking dorsal tergites. Genitoabdomen wider than long; anal prominence (indicated by arrowhead in Fig. 181B ) small; genital apertures positioned subdistally on same plane as anal prominence. Caudal rami and caudal setae absent.

Rostrum absent, but sclerotized longitudinal sculpture present in rostral area ( Fig. 181C ). Antennule ( Fig. 181D ) 55 μm long, narrowing distally, 3-segmented; first segment unarmed; second segment with 1 seta on posterior mar- gin; third segment slightly shorter than second, armed with 7 setae. Antenna ( Fig. 181E ) 67 μm long, unarmed, consisting of spinulose basal segment and spinulose distal claw; claw 34 μm long, curved, as long as basal segment, with acutely pointed tip.

Labrum ( Fig. 181F ) spinulose, with convex posterior margin, 1 broad, triangular, tongue-like medial process and 2 densely spinulose setiform processes, 1 either side of medial process. Mandible absent. Maxillule ( Fig. 181G ) distally bilobed; longer inner lobe tipped with 2 spinulose setae and densely covered with setules in distal half of lobe; shorter outer lobe tipped with 2 equal, spinulose setae. Maxilla ( Fig. 181H ) massive, 2-segmented; proximal segment with strongly protruding medial margin and 1 blunt tubercle near apex of medial protrusion; distal segment terminating in strong claw, with 1 small seta proximally on posterolateral surface and patch of fine granular ornamentation near base of seta. Maxilliped absent.

Leg 1 ( Fig. 181I ) biramous with 2-segmented protopod; protopod spinulose on anterior surface. Rami rudimentary; exopod as conical claw, embedded in transparent covering; endopod wider than long, truncate. Legs 2-4 same as leg 1 in form and structure. Leg 5 absent. Leg 6 not visible in genital aperture.

Male. Unknown.

Remarks. bnterçpsẚs çbtusa sp. nov. can be clearly defined by its characteristic labrum which bears a broad, linguiform median process plus a pair of slender, setiform processes laterally. The caudal rami are absent in b. çbtusa sp. nov., as in four congeneric species (b. abbçttẚ, b. fusẚfçrmẚs, b. mẚnçr, and b. elçngata sp. nov.). However, in b. çbtusa sp. nov. the antennule is 3-segmented, in contrast to the 1-segmented condition in these congeners, and the inner and outer lobes of the maxillule are each tipped with 2 distinct, basally articulating setae, compared to the armature of the inner and outer lobes each bearing 2 setae and 2 cusps in b. abbçttẚ, 0 and 2 setae in b. fusẚfçrmẚs, 2 and 0 setae in b. mẚnçr, and 2 setae and 1 cusp in b. elçngata sp. nov. The new species can be characterised by the combination of the armature of the labrum, the lack of caudal rami, the 3-segmented antennule, and the 2 setaebearing lobes of the maxillule.

Figures

FIG. 181. bnterçpsẚs çbtusa sp. nov., female. A, habitus, dorsal; B, habitus, right; C, cephalosome, ventral; D, antennule; E, antenna; F, labrum; G, maxillule; H, maxilla; I, leg 1. Scale bars: A, B, 0.1 mm; C, 0.05 mm; D-I, 0.02 mm.