Enterocola unisetosus, 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 : 241-244

Enterocola unisetosus sp. nov.

( Figs. 158 , 159 )

Type material. Holotype ♀ (MNHN-IU-2014-21568, dissected and mounted on a slide) from mçlyclẚnum sp.; Saldana Bay , South Africa, Monniot coll., 02 August 1996.

Etymology. The name is derived from the Latin unẚ (=one) and set (=a bristle), referring to the presence of a single seta on the endopods of legs 1-4.

Description of female. Body ( Fig. 158 A-C) eruciform, slightly curved dorsally; body length 1.48 mm; maximum width 480 μm (across second pedigerous somite). Cephalosome 240×338 μm, distinctly narrower than trunk, indistinctly defined from trunk. Trunk unsegmented, but with faint wrinkles dorsally and laterally between somites; first to third pedigerous somites bearing small dorsolateral tergal folds. Fourth pedigerous somite produced dorsally ( Fig. 158C ), bearing pair of ventral interpodal protrusions ( Fig. 158B ). Genitoabdomen ( Fig. 158D ) incompletely 4-segmented; anal prominence obscure. Caudal rami ( Fig. 158E ) short, 1.07 times longer than wide (61×57 μm), unarmed, with rounded distal margin.

Rostrum absent. Antennule ( Fig. 158F ) unsegmented, semicircular, wider than long (55×72 μm), armed with 1 small tubercle in middle of posterior side and 1 broad, naked seta (32 μm long) posterodistally; and ornamented with 2 rows of minute spinules distally. Antenna ( Fig. 158G ) indistinctly 2-segmented; proximal segment unarmed; distal segment armed with 6 setae; lengths of setae I-VI (medial to lateral) 36, 57, 54, 59, 69, and 58 μm, respectively.

Labrum ( Fig. 158H ) with scattered spinules on ventrolateral surface; palp spinulose, broad, leaf-like. Mandible ( Fig. 158H ) spinulose, gradually narrowing distally, narrower but longer than labral palp. Maxillule consisting of precoxa ( Fig. 158J ) and palp ( Fig. 158I ); precoxa bifurcate distally, with endite bearing 1 spinulose spine (without tuft of setules or spinules); palp armed with 6 stout, subequal spines (5 on distal margin and 1 on lateral margin). Maxilla ( Fig. 158K ) 2-segmented; mediodistal process of proximal segment truncate, bearing 2 small tubercles distally, surface covered with granules; distal segment bifurcate distally, with numerous granules on anterior surface and 1 stout seta proximally on posterior surface. Maxilliped absent.

Legs 1-4 each consisting of unarmed, distinctly 2-segmented protopod and unsegmented rami ( Fig. 159 A-C); protopods ornamented with multiple rows of fine spinules on anterior surface. Exopods of leg 1 and 2 with 2 small claws (distal and subdistal) and 3 patches of minute spinules on lateral margin ( Fig. 159A ); exopod of leg 3 attenuated, lacking claw or spinules ( Fig. 159B ); exopod of leg 4 tipped with small claw ( Fig. 159C ). Endopods of legs 1-4 armed with single seta distally; endopodal segments about twice longer than wide, with convex lateral margin. Setae on endopods about 1.2 times longer than endopodal segment.

Leg 5 ( Fig. 159D ) unarmed, wider than long (172×246 μm). Leg 6 ( Fig. 159E ) probably represented by 2 small spinules on genital operculum.

Male. Unknown.

Remarks. bnterçcçla unẚsetçsus sp. nov. is clearly recognizable by one striking feature: the presence of only a single seta on the endopods of swimming legs 1-4. No other species has 1 seta on all legs. In b. çlẚgçsetçsus sp. nov. the endopod of leg 4 is armed with 1 seta, but legs 1-3 typically have 2 setae. In some other bnterçcçla species, one of the 2 distal setae on the endopods can be reduced to a minute setule-like vestige, such as in legs 3 and 4 of b. cçnẚculus and b. mçnnẚçtẚ ( Ooishi, 2014a; Marchenkov & Boxshall, 2005), but in none of these has one of the distal setae been lost from all swimming legs, as in the new species. The leg setation of b. unẚsetçsus sp. nov. seems to represent an intermediate condition between the typical bnterçcçla pattern and that of bnterçcçlẚdes, in which the endopods of legs 3 and 4 are unarmed, as redefined in the present work.

Genus Enterocolides Chatton & Harant, 1922

Diagnosis. Female: Body form and most morphological features as in bnterçcçla, except as follows: genitoabdomen short, unsegmented, lacking caudal rami. Palp of maxillule lacking lateral seta, or this seta vestigial. Endopods of legs 1 and 2 unarmed or armed with 2 setae distally; endopods of legs 3 and 4 unarmed.

Type species. bnterçcçlẚdes ecaudatus Chatton & Harant, 1922 by original designation.

Remarks. Until now bnterçcçlẚdes has remained a monotypic genus and its type species was redescribed by Illg & Dudley (1980). In its original description, Chatton & Harant (1922) separated this genus from bnterçcçla by its unsegmented abdomen, the lack of caudal rami, the lack of setae on the endopods of swimming legs, the presence of a supplementary claw on the exopods of legs 1 and 2, and by the dorsal position of the anus. Later authors (Illg & Dudley, 1980; Boxshall & Halsey, 2004) recognized the absence of setae on the endopods of the swimming legs as a key character of bnterçcçlẚdes.

A new species bnterçcçlẚdes pacẚfẚcus sp. nov. is described below and is placed in bnterçcçlẚdes even though it carries a pair of setae on the endopods of legs 1 and 2. It shares the lobate genitoabdomen lacking caudal rami, the reduction of the lateral seta on the maxillular palp, and the lack of setae on the endopods of legs 3 and 4,with the type species bK ecaudatus and, on the balance of evidence available, we therefore place the new species in bnterçcçlẚdes rather than in bnterçcçla.

Figures

FIG. 158. bnterçcçla unẚsetçsus sp. nov., female.A, habitus, dorsal; B, habitus, ventral; C, habitus, right; D, leg 5 and genitoabdomen. dorsal; E, caudal rami; F, antennule; G, antenna; H, labrum and mandibles; I, palp of maxillule; J, precoxa of maxillule; K, maxilla. Scale bars: A-C, 0.2 mm; D, 0.1 mm; E, G, K, 0.05 mm; F, H-J, 0.02 mm.

FIG. 159. bnterçcçla unẚsetçsus sp. nov., female.A, leg 1; B, leg 3, C, leg 4; D, leg 5; E, genital aperture. Scale bars:A-C, 0.05 mm; D, 0.1 mm; E, 0.02 mm.