Enterocola australis Kim & Boxshall 2021, sp. nov.

Enterocola australis sp. nov.

(Figs. 144, 145)

Type material. Holotype ♀ (MNHN-IU-2014-21555), 7 ♀♀ paratypes (MNHN-IU-2014-21556), and 1 ♀ paratype (dissected, MNHN-IU-2014-21473) from mseudçdẚstçma sp. (MNHN-IT-2008-7383 = MNHN A1 / PSE/45); South Africa, Ouderkraal, SAA 55, depth 8 m, Griffiths coll., 18 August 1994.

Etymology. The specific name is derived from the Latin austral (=southern), indicating the location of the type locality in South Africa.

Description of female. Body (Fig. 144 A-C) eruciform, depressed, curved dorsally; body length 1.45 mm; maximum width 650 μm (across second pedigerous somite). Cephalosome 335×509 μm, well-defined from first pedigerous somite. Trunk distinctly segmented; first to fourth pedigerous somites bearing simple, distinct dorsal tergites, without dorsolateral tergal folds. Ventral interpodal protrusions not developed (Fig. 144B). Genitoabdomen (Fig. 144D) gradually narrowing posteriorly, unsegmented dorsally but 5-segmented ventrally, with many incomplete transverse rows of minute spinules (Fig. 144E, F); anal prominence distinct, with large anal opening (Fig. 142E). Caudal rami (Fig. 144 D-F) widely separated from each other, slightly divergent, unarmed, about 2.5 times longer than wide (133×54 μm), gradually narrowing distally towards rounded distal margin.

Rostrum absent.Antennule (Fig. 144G) indistinctly 2-segmented, tapering, 1.47 times longer than wide (100×68 μm); proximal segment with 4 setae and ornamented with scattered minute spinules distally; distal segment small, semicircular, armed with 3 small, setule-like setae on distal margin. Antenna (Fig. 144H) more than twice as long as wide (203×95 μm), obscurely 2-segmented, ornamented with rows of minute spinules on convex surface; proximal segment unarmed; distal segment with 6 naked setae (1 small seta on medial margin and 5 large setae on oblique distal margin); lengths of setae I-VI 27, 93, 93, 109, 125, and 118 μm, respectively; setae III-V geniculate near base; seta I positioned at 70% along medial margin of segment.

Labrum (Fig. 144I) with 3 patches of spinules on each side; palp spinulose, gradually narrowing distally, not expanded. Mandible (Fig. 144I) spinulose, slender, much narrower than labral palp. Maxillular precoxa (Fig. 144J) with bifurcate distal part; endite tipped with 1 spinulose spine and array of several spinules; palp (Fig. 145A) with 6 spinulose elements including slender lateral seta. Maxilla (Fig. 145B) 2-segmented; mediodistal endite on proximal segment bearing thick, basally articulating, spiniform element; distal segment bifurcate, smooth, with 1 small seta proximally. Maxilliped absent.

Legs 1-4 (Fig. 145 C-F) each consisting of 2-segmented protopod and 1-segmented rami; protopods unarmed. Exopods distinctly shorter than endopods; exopod of leg 3 not elongated. Endopods slender, more than twice as long as wide; 125×49, 139×48, 130×50, and 116×48 μm, respectively, in legs 1-4. Lengths of laterodistal and mediodistal setae 143 and 220, 130 and 215, 107 and 214, and 91 and 200 μm, respectively, in legs 1-4. Laterodistal setae much shorter than mediodistal setae.

Leg 5 (Fig. 145G) lamellate, wider than long (127×253 μm), armed with 2 setae (both 56 μm long) on distal margin and ornamented with numerous rows of minute spinules on convex surface; distance between 2 setae 123 μm.

Male. Unknown.

Remarks. In b. australẚs sp. nov. the laterodistal setae on the endopods of legs 1-4 are distinctly shorter than the mediodistal setae, less than 0.7 times as long as the latter. This is a distinctive feature of the new species, considering that the laterodistal setae are typically longer than the mediodistal setae in bnterçcçla species. Only four species, b. cçnẚculus, b. fulgens, b. latẚceps, and b. petẚtẚ Guille, 1964, are known to diverge from this pattern and are compared with the new species in more detail.

Unlike the new species, b. cçnẚculus lacks caudal rami (a characteristic feature of this species). In b. fulgens the caudal rami are about 1.6 times longer than wide (cf. 2.5 times in the new species), the antennule is 3-segmented (cf. indistinctly 2-segmented), and the distal setae on the endopods of legs 1-4 are much shorter than the endopodal segments (cf. often longer). In b. latẚceps the antennule is elongate (cf. not elongate in new species), both rami of legs 1-4 are 2-segmented (cf. 1-segmented), and the antenna is armed with 5 setae (cf. 6 setae). Finally, in the redescription of b. petẚtẚ by Illg & Dudley (1980) the caudal rami are as long as wide (cf. 2.5 times in new species), the first to fourth pedigerous somites bear tergal folds (cf. absent), and the endopodal segments of legs 1-4 are short, only slightly longer than wide (cf. more than twice as long as wide).

Other notable features of b. australẚs sp. nov., are the elongate endopods of legs 1-4 which are more than twice as long as wide, and leg 5 bears relatively large setae.