Enterocolides elongatus, 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 : 248

Enterocolides elongatus sp. nov.

( Figs. 163 , 164 )

Type material. Holotype ♀ (MNHN-IU-2014-21573, dissected and mounted on a slide) from aẚstaplẚa sp.; Red Sea coast of Israel, 1962.

Etymology. The name of the new species refers to its elongate body.

Description of female. Body ( Fig. 163 A-C) vermiform, cylindrical, curved dorsally; body length 1.58 mm; maximum width 292 μm (across fourth pedigerous somite). Cephalosome wider than long (154×192 μm), narrower than trunk, indistinctly articulated from trunk. Trunk unsegmented, gradually broadening posteriorly; first to fourth pedigerous somites defined from one another by weak lateral constrictions, each somite with pair of distinct tergal folds dorsolaterally ( Fig. 163A ) and pair of large, lobate ventral protrusions ( Fig. 163B ). First and second pedigerous somites ornamented with rows of minute spinules on dorsal surface ( Fig. 163A ). Genitoabdomen short, slightly longer than wide, unsegmented, not articulated from trunk, with copulatory pore ventrally and small anal prominence dorsally. Caudal rami very small, widely separated from each other; each ramus ( Fig. 163D ) about 1.8 times longer than wide (33×18 μm), unarmed, with parallel lateral margins and rounded distal margin.

Rostrum not developed. Antennule ( Fig. 163E ) tapering, about 65 μm long, incompletely 3-segmented, not articulated at base, but with sclerotized band at base; first segment with 1 small seta anterodistally and several blunt spinules in middle; second segment short with 2 setae on anterior margin; third segment with 5 setae, largest terminal seta process-like, not articulated at base. Antenna ( Fig. 163F ) lamellate, unsegmented, longer than wide, and ornamented with scattered rows of minute spinules on anterior and posterior surfaces; armed with 5 naked setae (4 distal and 1 subdistal).

Labrum ( Fig. 163G ) with convex posterior margin, ornamented with 3 groups of minute spinules on each side of ventral surface; with pair of narrow, spinulose palps. Mandible small, similar to labral palp. Maxillule ( Fig. 163H ) biramous, consisting of precoxa and palp; precoxa ( Fig. 163I ) terminating in spiniform process, with endite tipped with 1 spinulose spine and several spinules encircling spine, and armed with 2 spinulose spines near base of process; palp ( Fig. 163J ) bearing 4 spinulose spines on distal margin and 1 slender, naked seta on lateral margin. Maxilla ( Fig. 163K ) 2-segmented; proximal segment with strongly projecting mediodistal corner tipped with robust, spinulose spine; distal segment armed with 2 naked spines (1 distal and 1 subdistal) and 1 strong naked seta on posterior surface. Maxilliped absent.

Legs 1-4 ( Fig. 164 A-D) each consisting of unarmed 2-segmented protopod and unsegmented rami. Proximal segment (coxa) of protopod short, indistinct, ornamented with several rows of minute spinules. Exopods of legs 1 and 2 terminating in spiniform process and 1 small, claw-like spine subdistally on lateral margin. Lengths of exopods 40, 45, 58, and 38 μm, respectively, in legs 1-4; exopod of leg 3 ( Fig. 164C ) attenuated, acutely pointed distally; exopod of leg 4 tipped with 1 small spine ( Fig. 164D ). Endopods of legs 1-4 as large, flattened, laterally curved, tapering element, sclerotized along medial margin, acutely pointed distally in legs 1-3, but with blunt tip in leg 4. Sizes of endopods 102×29, 173×33, 179×38, and 147×36 μm, respectively, in legs 1-4.

Leg 5 ( Fig. 164E ) lamellate, wider than long, with obliquely rounded ventral margin and straight dorsal margin; armed with 2 minute, almost invisible setae.

Male. Unknown.

Remarks. In the possession of distinct rami on the swimming legs, the lamellate antenna and leg 5, and the labrum bearing a pair of palps, bnterçcçlẚdes elçngatus sp. nov. belongs to the bnterçcçla -bnterçcçlẚdes -iequerrea lineage. Within this small cluster of genera, the new species is included in bnterçcçlẚdes due to the presence of both antennules and antennae, and to the possession of unarmed endopods on swimming legs 1-4. However, the new species differs markedly from its two congeners, b. ecaudataus and b. pacẚfẚcus sp. nov. as follows: the endopods of the swimming legs are attenuated and extremely elongated, caudal rami are present (although very small), the first to fourth pedigerous somites bear dorsal tergal folds and ventral interpodal protrusions, and the precoxa of the maxillule and distal segment of the maxilla are armed with spines or spiniform processes. The relatively plesiomorphic condition of the maxillule and maxilla, and the apomorphic state of the swimming legs are the most notable characters defining the new species, but it is clear that the relationships between these genera are in need of further analysis, perhaps when males become known.

Figures

FIG. 163. bnterçcçlẚdes elçngatus sp. nov., female.A, habitus, dorsal (left leg 5 damaged); B, habitus, ventral; C, habitus, right; D, caudal ramus; E, antennule; F, antenna; G, labrum; H, maxillule; I, precoxa of maxillule; J, palp of maxillule; K, maxilla. Scale bars: A-C, 0.2 mm; D-K, 0.02 mm.

FIG. 164. bnterçcçlẚdes elçngatus sp. nov., female. A, leg 1; B, leg 2; C, leg 3; D, leg 4; E, leg 5. Scale bars: 0.05 mm.