Enterocola nodulosus, 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 : 235-236

Enterocola nodulosus sp. nov.

( Fig. 153 , 154 )

Type material. Holotype ♀ (MNHN-IU-2014-21563, dissected and mounted on a slide) from budẚstçma sp.; Indonesia, no other collection data.

Etymology. The name of the new species alludes to the presence of a distal nodule on the endopods of the swimming legs.

Description of female. Body ( Fig. 153 A-C) eruciform, curved dorsally; body length 909 μm; maximum width 350 μm (across second pedigerous somite). Cephalosome with convex posterodorsal margin. Trunk unsegmented, but pedigerous somites defined from one another by dorsal and lateral constrictions; second to fourth pedigerous somites each bearing pair of dorsal tergal folds ( Fig. 153A, C ) and single, large, plate-like ventral interpodal protrusion between left and right legs ( Fig. 153B ). Genitoabdomen ( Fig. 153D ) unsegmented dorsally but 4-segmented ventrally; segmentation indistinct between genital and first free abdominal somites. Free abdominal somites covered with ornamentation of minute spinules on all surfaces; anal prominence distinct. Caudal rami ( Fig. 153D ) straight, incompletely articulated from anal somite, gradually narrowing distally, unarmed, about 2.6 times longer than wide (100×38 μm).

Rostrum absent. Antennule ( Fig. 153E ) leaf-like, 39×27 μm, inflated posteriorly, with convex posterior margin; armed with 5 small, subequal setae at apex. Antenna ( Fig. 153F ) about 2.6 times longer than wide, incompletely 2- segmented, slightly curved medially; proximal segment unarmed; distal segment ornamented with minute spinules on convex surface; armed with 6 thin setae, lengths of setae I-VI 20, 18, 23, 19, 32, and 64 μm, respectively; seta I naked, but other 5 setae weakly pinnate; setae I-III widely separated from setae IV-VI.

Labrum ( Fig. 153G ) with spinulose, distally swollen palps. Mandible ( Fig. 153G ) spinulose, tapering, narrower than labral palp. Maxillule consisting of precoxa ( Fig. 153H ) and palm-shaped palp ( Fig. 153I ); precoxa with bifurcate distal part, 1 small tubercle subdistally, and endite in middle bearing 1 spinulose seta and more than 20 thin spinules; palp with 6 spinulose spines. Maxilla ( Fig. 153J ) with bifurcate, spinulose mediodistal process on proximal segment; distal segment with 1 robust, basally articulated, spinulose spine subdistally, 1 transverse row of minute spinules on middle of anterior surface, and 1 small seta on posterior surface. Maxilliped absent.

Legs 1-4 each consisting of unarmed, 2-segmented protopod and unsegmented rami. Exopods bearing patch of spinules proximally on lateral margin (( Fig. 154 A-C). Endopods armed distally with 2 naked setae and 1 nodule. Sizes of endopods 55×25, 55×24, 55×32, and 48×27 μm, respectively, in legs 1-4; endopods of legs 3 and 4 with markedly protruded lateral margin. Lengths of laterodistal and mediodistal setae 56 and 50, 55 and 43, 55 and 40, and 58 and 39 μm, respectively, in legs 1-4. Laterodistal setae longer than or as long as endopodal segments and about 1.1, 1.3, 1.4, and 1.5 times longer than mediodistal setae in legs 1-4, respectively.

Leg 5 ( Fig. 153K ) lamellate, unarmed, much wider than long (129×255 μm).

Male. Unknown.

Remarks. bnterçcçla nçdulçsus sp. nov. is characterized by the presence of a nodule (small tubercle) distally on the endopods of swimming legs 1 to 4. In addition, the unsegmented antennule of the new species is inflated and leaf-like. This form of the antennule (bulbous or D-shaped) is shared with ten known species of bnterçcçla ( Table 6 ). Interestingly, in species with this form of antennule, the body is small (mostly less than 1.0 mm long), and the laterodistal setae on the endopods of swimming legs are shorter than endopodal segments but as long as or longer than the mediodistal setae. Six of those species (b. parapterçphçrus, b. dẚcaudatus, b. quadrẚsetus sp. nov., b. mabulensẚs sp. nov., b. parvus sp. nov., and b. neçcaledçnẚcus sp. nov.) can be eliminated from further comparison because they have fewer than 6 setae on the antenna (cf. 6 setae in b. nçdulçsus sp. nov.), or 1 or 2 dorsal tubercles or processes on the cephalosome or pedigerous somites (cf. lacking in b. nçdulçsus sp. nov.).

The remaining four species (b. mammẚferus, b. pterçphçrus, b. rçbustus sp. nov., and b. angustus sp. nov.) can be distinguished from the new species as follows: in b. mammẚferus the caudal rami are wider than long (cf. about 2.6 times longer than wide in b. nçdulçsus sp. nov.), the antennule is armed with 4 setae (cf. 5 setae), the 6 setae on the antenna are subequal in length (cf. setae unequal), and the 2 distal setae on the endopods of legs 1-4 are almost equal in length, as described or illustrated by Ooishi (2010b). In b. pterçphçrus (as redescribed above), the ventral interpodal protrusion is absent on the pedigerous somites (cf. present, large in second to fourth pedigerous somites of b. nçdulçsus sp. nov.), the lateral seta (seta VI) of the antenna is 34 μm long, distinctly shorter than that of b. nçdulçsus sp. nov. (cf. 64 μm long), the labral palp is less expanded, and the mediodistal element of the proximal maxillary segment is articulated at base and simple, not bifurcate. In b. rçbustus sp. nov. the antennule is armed with 3 setae ((cf. 5 setae in b. nçdulçsus sp. nov.), the mediodistal element of the proximal maxillary segment is simple, not bifurcate, the setae on the antenna are shorter, the longest lateral seta (seta VI) is only 22 μm long (cf. 64 μm long), and the distal setae on the endopods of legs 1-4 are distinctly shorter than endopodal segments (cf. the setae are equal or subequal in length to endopodal segments in b. nçdulçsus sp. nov.). Finally, in b. angustus sp. nov. the caudal rami are strongly tapering and about 1.9 times longer than wide (cf. about 2.6 times longer than wide in b. nçdulçsus sp. nov.), the longest lateral seta (seta VI) of the antenna is 29 μm long (cf. 64 μm long), the ventral interpodal protrusions on pedigerous somites are obscure, weakly developed (cf. large and well developed), and the distal setae on the endopods of legs 1-4 are distinctly shorter than endopodal segment (cf. as long as or longer).

Figures

FIG. 153. bnterçcçla nçdulçsus sp. nov., female. A, habitus, dorsal; B, habitus, ventral; C, habitus, right; D, genitoabdomen, ventral; E, antennule; F, antenna; G, labrum and mandibles; H, precoxa of maxillule; I, palp of maxillule; J, maxilla; K, leg 5. Scale bars: A-C, 0.1 mm; D, K, 0.05 mm; E-J, 0.02 mm.

FIG. 154. bnterçcçla nçdulçsus sp. nov., female.A, leg 1; B, leg 3; C, leg 4. Scale bars: 0.02 mm.