Enterocola oligosetosus, 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 : 237

Enterocola oligosetosus sp. nov.

( Figs. 155 , 156 )

Type material. Holotype ♀ (MNHN-IU-2014-21564), 3 ♀♀ paratypes (MNHN-IU-2014-21565), and 1 ♀ para- type (dissected, MNHN-IU-2014-21478) from aẚdemnum sp.; Guadeloupe, Îlet aux Pigeons, Stn 20, depth 5-12 m, Monniot coll., 27 December 1980.

Etymology. The name of the new species refers to the presence of a single seta on the endopod of leg 4.

Description of female. Body ( Fig. 155 A-C) eruciform, curved dorsally; body length 968 μm in largest dissect- ed specimen; maximum width 386 μm (across second pedigerous somite). Cephalosome clearly defined, 168×263 μm, distinctly narrower than trunk. Trunk inflated, unsegmented, but 4 anterior pedigerous somites defined by lateral constrictions between them; first to third pedigerous somites bearing small dorsolateral tergal folds; fourth pedigerous somite narrower than anterior pedigerous somites, bearing dorsal tergite. Ventral interpodal protrusions absent. Genitoabdomen ( Fig. 155D ) gradually narrowing posteriorly, 5-segmented; articulations obscure dorsally; articulation between last 2 somites incomplete. Caudal ramus ( Fig. 155E ) tapering, incompletely articulated from anal somite, about 1.85 times longer than wide (76×41 μm), blunt distally; armed with 1 weakly pinnate, dorsal seta at 70% of ramus length; seta length 44 μm, more than half length of ramus.

Rostrum absent. Antennule ( Fig. 155F ) incompletely 2-segmented, about 76×40 μm, with inflated proximal two-thirds and narrow distal third; proximal segment with convex posterior margin armed with 3 setae (1 subdistal and 2 distal); distal segment small, 11×7 μm, rectangular, armed with 4 setae on distal margin. Antenna ( Fig. 155G ) elongate, about 2.7 times longer than wide (145×54 μm), unsegmented, and ornamented with several patches of minute spinules on concave surface; armed with 5 unequal setae, lengths of setae (medial to lateral) 19, 9, 9, 45, and 41 μm, respectively; setae II and III small, close to each other and positioned at mediodistal corner, both setae widely separated from seta I and setae IV and V; seta IV and V distinctly larger than other setae, originating close to each other, positioned at laterodistal corner.

Labrum ( Fig. 155H ) with 2 patches of minute spinules on each side of ventral surface; palp densely spinulose, gradually expanded distally. Mandible ( Fig. 155H ) spinulose, about half as wide as labral palp. Maxillule consisting of precoxa ( Fig 156A ) and palp ( Fig. 156B ); precoxa with bifurcate distal part, 1 subdistal tubercle, and endite tipped with 1 seta, (proximally plumose and distally spinulose); palp with 5 spinulose setae on distal margin and 1 naked seta on lateral margin. Maxilla ( Fig. 155I ) 2-segmented; proximal segment with bifurcate mediodistal process bearing fine spinules distally; distal segment bifurcate distally, with 1 small seta proximally on posterior surface. Maxilliped absent.

Legs 1-4 each consisting of unarmed, 2-segmented protopod and unsegmented rami ( Fig. 156 C-E). Exopods with 3 patches of minute spinules along lateral margin. Endopods of legs 1-3 armed with 2 setae distally, but endopod of leg 4 armed with 1 seta distally (in 1 of 5 examined specimens, endopods of legs 2-4 armed with 1 seta), all setae weakly pinnate. Endopodal segments 59×30, 64×31, 64×30, and 58×33 μm, respectively, in legs 1-4. Lengths of laterodistal and mediodistal setae 59 and 42, 66 and 41, and 68 and 41 μm, respectively, in legs 1-3. Length of distal seta on leg 4 endopod 68 μm.

Leg 5 ( Fig. 155J ) unarmed, wider than long (98×180 μm).

Male. Unknown.

Remarks. This new species is very easily distinguishable from all of its congeners by the possession of a single seta on the endopod of leg 4. The combination of three other character states, the caudal ramus is armed with 1 seta, the antenna is elongate and armed with 5 setae, and the distal setae on the endopods of all swimming legs are pinnate, provides additional evidence supporting the establishment of the new species.

Figures

FIG. 155. bnterçcçla çlẚgçsetçsus sp. nov., female. A, habitus, dorsal; B, habitus, ventral; C, habitus, right; D, genitoabdomen, ventral; E, left caudal ramus, lateral; F, antennule; G, antenna; H, labrum and mandibles; I, maxilla; J, leg 5. Scale bars: A-C, 0.1 mm; D, J, 0.05 mm; E-I, 0.02 mm.

FIG. 156. bnterçcçla çlẚgçsetçsus sp. nov., female. A, precoxa of maxillule; B, palp of maxillule; C, leg 1; D, leg 3; E, leg 4. Scale bars: 0.02 mm.