Enterocola mabulensis, 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 : 212-213

Enterocola mabulensis sp. nov.

( Figs. 136 , 137 )

Type material. Holotype ♀ (MNHN-IU-2014-21548), 1 ♀ paratype (MNHN-IU-2014-21549), and 1 ♀ paratype (dissected, MNHN-IU-2014-17398) from aẚdemnum sp.; NW channel running due West from SMART resort, Mabul, Malaysia, ODHG 1301 W, depth 20 m, CRRF coll., 04 July 2004.

Etymology. The name of the new species is derived from its type locality, Mabul, Malaysia.

Description of female. Body ( Fig. 136 A-C) unsegmented, narrow, cylindrical, curved dorsally, and slightly compressed laterally. Body length 815 μm in dissected largest specimen; maximum width 230 μm (across fourth pedigerous somite). Cephalosome partially covered by cephalic shield; first pedigerous somite also partially covered with tergite. Second to fourth pedigerous somites each bearing well-developed dorsolateral tergal folds; these tergal folds digitiform, with blunt, posteriorly-directed tip in dorsal view ( Fig. 136A ) but tapering in lateral view ( Fig. 136C ). Ventral surface of trunk bearing single interpodal protrusion between left and right members of legs 1-4. Genitoabdomen short, obscurely defined from trunk, lacking any trace of articulation; anal prominence distinct. Caudal rami ( Fig. 136D ) unarmed, 1.53 times longer than wide (49×32 μm), narrowing distally, with rounded distal margin. Egg sac ( Fig. 136E ) 519×188 μm, slightly curved, containing 2 or 3 rows of eggs; each egg about 130 μm in diameter.

Rostrum absent. Antennule ( Fig. 136F ) small, about 1.3 times longer than wide (38×29 μm), widest in proxi- mal third, with straight anterior margin and inflated posterior margin; armed with 5 (1 subdistal and 4 distal) small setae, one distal seta 12 μm long (larger than other setae). Antenna ( Fig. 136G ) unsegmented, about 115×54 μm, ornamented with minute spinules on convex surface of distal region; armed with 5 minutely spinulose setae, setae at most as long as half width of antenna; lengths of setae I-V: 16, 21, 18, 18, and 27 μm, respectively.

Labrum ( Fig. 136H ) almost circular in ventral view; palp distally expanded, bulbous, covered with fine spinules. Mandible spinulose, tapering, much narrower than labral palp. Maxillule consisting of precoxa and palp; precoxa ( Fig. 136I ) with distal sclerotized part with bluntly bifurcate distal margin and 1 prominent tubercle on medial side; endite bearing 1 spiniform naked seta and more than 10 long setules: palp ( Fig. 136J ) with 6 spinulose setae. Maxilla ( Fig. 136K ) 2-segmented; proximal segment with mediodistal endite bearing large spinulose process; distal segment with bifurcate distal part, armed subdistally with 1 stout spine bearing numerous spinules on medial surface, plus 1 small seta proximally on posterior surface. Maxilliped absent.

Legs 1-4 consisting of unsegmented protopods and unsegmented rami ( Fig. 137 A-C); protopods unarmed. All exopods shorter than endopods: exopods of legs 1, 2, and 4 tipped with small cusp; exopod of leg 3 attenuated ( Fig. 137B ). Endopods of legs 1 and 2 subdivided by partial suture line on medial side; endopod of leg 4 with distinctly convex lateral margin. Endopods 42×22, 52×24, 47×22, and 35×22 μm, respectively, in legs 1-4. Laterodistal and mediodistal setae on endopods distinctly shorter than endopodal segments, 27 and 20 μm in leg 1, 25 and 22 μm in leg 2, and 31 and 25 μm in legs 3 and 4.

Leg 5 ( Fig. 137D ) unarmed, oval, 127×125 μm, not widened. Leg 6 probably represented by 1 small cusp in genital area ( Fig. 136L ).

Male. Unknown.

Remarks. The antenna of b. mabulensẚs sp. nov. is armed with 5 setae, a feature shared with three existing species: b. adnatus Ooishi, 2014; b. latẚceps, and b. parapterçphçrus. These three species can be distinguished from b. mabulensẚs sp. nov. by various different features, as follows: bK adnatus lacks caudal rami, the antennule is 2- segmented, and the endopodal setae on swimming legs are longer than the endopodal segments ( Ooishi, 2014a); bK latẚceps has caudal rami that are more than twice as long as wide (about 1.5 times longer in b. mabulensẚs sp. nov.), the antennule is armed with as many as 16 setae, and both rami of swimming legs are 2-segmented (Illg & Dudley, 1980); finally, in bK parapterçphçrus the caudal rami are more than twice as long as wide, as measured from Marchenkov & Boxshall (2005: Fig. 8g ), and the antenna is 2-segmented.

In all species of bnterçcçla for which leg 5 is known, this limb is wider than long. The ovoid form of leg 5 of female b. mabulensẚs sp. nov., which is slightly longer than wide, is unusual for the genus and may also serve to distinguish the new species.

Figures

FIG. 136. bnterçcçla mabulensẚs sp. nov., female. A, habitus, dorsal; B, habitus, ventral; C, habitus, right; D, caudal rami; E, egg sac; F, antennule; G, antenna; H, labrum; I, precoxa of maxillule; J, palp of maxillule; K, maxilla; L, genital aperture. Scale bars: A-C, E, 0.01 mm; D, F-L, 0.02 mm.

FIG. 137. bnterçcçla mabulensẚs sp. nov., female. A, leg 1; B, leg 3; C, leg 4; D, leg 5. Scale bars: A-C, 0.02 mm; D, 0.05 mm.

FIG. 8. Styelẚcçla bahusẚa Lützen, 1968, female.A, habitus, right; B, urosome, dorsal; C, right caudal ramus, ventral; D, antennule; E, antenna; F, mandible; G, paragnath; H, maxillule; I, maxilla; J, K, maxilliped; L, leg 5, medial; M, exopod of leg 5; N, genital aperture. Scale bars: A, 0.5 mm; B, L, M, 0.1 mm; C, D, G, I, 0.05 mm; E, F, H, J, K, N, 0.02 mm.