Haplostoma vanuatuense, 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 : 149

Haplostoma vanuatuense sp. nov.

( Fig. 96 )

Type material. Holotype ♀ (MNHN-IU-2018-1996, dissected and mounted on a slide) from ohçpalaea desme Monniot F., 2003 (Type MNHN-IT-2008-7888 = MNHN P1 / RHO.A/32); S. Anatom Is., Vanuatu, MUSORSTOM 8 cruise, RV “Alis”, Stn CP 961 (20°18´S, 169°50´E), depth 100-110 m, Bouchet & Richer de Forges-IRD coll., 21 September 1994.

Etymology. The type locality, Vanuatu, provides the name of the new species.

Description of female. Body ( Fig. 96A, B ) eruciform, narrow, slightly curved dorsally: body length 2.43 mm, maximum width 540 μm and maximum dorsoventral depth of 570 μm both at level of second pedigerous somite. Cephalosome and 4 metasomites defined by lateral constrictions; fourth metasomite compound, consisting of fused fourth and fifth pedigerous somites. Genitoabdomen slightly longer than wide (277×270 μm), distinctly 3-segment- ed, consisting of genital somite and 2-segmented abdomen. Genital somite comprising broad anterior and narrower posterior parts; genital apertures positioned dorsally. Caudal ramus ( Fig. 96C ) tapering, slightly wider than long (38×40 μm); armed with 1 claw-like distal spine, 1 subdistal seta, and 1 outer seta. Egg sac longer than body, coiled, containing about 5 rows of eggs; each egg about 200 μm in diameter.

Rostrum absent, but rostral area sclerotized ( Fig. 96D ). Antennule ( Fig. 96E ) incompletely 2-segmented, armed with 1 seta on proximal segment and 18 setae on distal segment; all setae short and bluntly tipped, except 5 longer, attenuated setae in distal region. Antenna ( Fig. 96F ) 2-segmented; proximal segment unarmed; distal segment narrower and shorter than proximal segment, 2.6 times longer than wide; armed with 4 simple spines, all articulated at base.

Labrum ( Fig. 96D ) well-developed, with 6 equal lobes along posterior margin, all of these lobes longer than wide and each with rounded apex. Mandible ( Fig. 96D ) twice as long as wide (33×16 μm), tapering, with 2 equal setae on apex. Maxillule and maxilla absent. Maxilliped ( Fig. 96G ) robust, 4-segmented; broad first segment unarmed; second segment bearing broad, short setae; small third and fourth segments unarmed; terminal claw small, bifurcate.

Leg 1 ( Fig. 96H ) consisting of protopod, exopod and endopod; protopod bearing 1 seta on outer margin; exopod incompletely defined from protopod, armed with 1 seta and 4 simple spines; endopod triangular, not articulated from protopod, shorter than exopod. Leg 2 ( Fig. 96I ) with 1 seta and 3 spines on exopod; endopod much larger than that of leg 1, as long as exopod, with small nipple-shaped tubercle on apex. Legs 3 and 4 similar to leg 2 in armature and shape, but lacking distal tubercle on endopod.

Leg 5 ( Fig. 96J ) small but distinct, digitiform, longer than wide (110×67 μm), not articulated at base; rounded distal margin armed with 4 thin setae (1 dorsal and 3 distal). Leg 6 ( Fig. 96K ) represented by 2 small spines, 1 larger spiniform process, and 7 denticles on genital operculum; 6 other internal denticles visible near leg 6.

Male. Unknown.

Remarks. eaplçstçma vanuatuense sp. nov. possesses 6 distinct, equal lobes on the posterior margin of the labrum and has a combination of 5, 4, 4, and 4 armature elements on the exopods of legs 1-4. Among previously known species only e. kẚmẚ Seo & Lee, 2001 recorded from the Sea of Japan ( Seo & Lee, 2001) shares both of these features. eaplçstçma kẚmẚ is distinguishable from e. vanuatuense sp. nov. by three main features: (1) the genitoabdomen is not segmented (cf. 3-segmented in e. vanuatuense sp. nov.); (2) the outer margins of legs 3 and 4 each bear a large protrusion near the base of the proximal seta (cf. such a protrusion is absent in e. vanuatuense sp. nov.); and (3) leg 5 is strongly tapering, with 1 proximal and 2 distal setae (cf. digitiform, with 1 proximal and 3 distal setae in e. vanuatuense sp. nov.). These differences are sufficient to justify the establishment of the new species.

Figures

FIG. 96. eaplçstçma vanuatuense sp. nov., female. A, habitus, dorsal; B, habitus, right; C, caudal rami, ventral; D, cephalic appendages ẚn sẚtu, ventral; E, antennule; F, antenna; F, maxilliped; H, leg 1; I, leg 2; J, leg 5; K, genital aperture. Scale bars: A, B, 0.5 mm; C, E-H, K 0.02 mm; D, J, 0.05 mm.