Haplostoma laticaudatum, 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 : 151

Haplostoma laticaudatum sp. nov.

( Figs 97 , 98 )

Type material. Holotype ♀ (MNHN-IU-2018-1997), 1 ♀ paratype (MNHN-IU-2018-1998), and 1 ♀ paratype (dis- sected MNHN-IU-2014-17384) from mseudçdẚstçma cyrnusense Pérès , 1952; Tunisia, no other collection data.

Etymology. The name is derived from the Latin lat (=broad) and cauda (=the tail), alluding to the broad caudal rami of the new species.

Description of female. Body ( Fig. 97A, B ) eruciform, slightly curved dorsally; body length 1.60 mm, maximum width 424 μm at region of leg 2. Cephalosome ( Fig. 97C, D ) not defined from first pedigerous somite ( Fig. 97A ), narrowing anteriorly. Metasomites defined only by constrictions; last metasomite consisting of fused fourth and fifth pedigerous somites. Genitoabdomen ( Fig. 97E ) consisting of genital somite and 2-segmented abdomen. Genital somite wider than long (118×200 μm), consisting of broader anterior and narrower posterior parts, with dorsal strip connecting paired genital apertures. First and second abdominal somites 27×109 and 55×90 μm, respec- tively. Caudal ramus ( Fig. 97F ) triangular, slightly wider than long (36×38 μm); armed with 1 seta on outer margin and 1 unequally bifurcate spine on apex. Egg sac longer than body, containing 2-4 rows of eggs; each egg about 140 μm in diameter.

Rostrum not developed, represented by produced frontal apex of cephalosome ( Fig. 97C ). Antennule ( Fig. 97G ) tapering, unsegmented, but with 3 or 4 partial suture lines along posterior side, armed with 16 small setae, fourth proximal seta with swollen base. Antenna ( Fig. 97H ) 2-segmented; proximal segment unarmed; distal segment as long as proximal, armed with 4 large, conical spines.

Labrum ( Fig. 97I ) with 6 large, blunt lobes along posterior margin, 2 lateral lobes on each side fused proximally (appearing as 2 bifurcate lobes and 2 simple lobes). Mandible ( Fig. 97I ) longer than wide, tipped with 1 or 2 small setae. Maxillule and maxilla absent. Maxilliped ( Fig. 98A ) tapering distally, 4-segmented; first segment unarmed; second segment incompletely articulated from first, slightly wider than long, armed with 2 small setae; third segment unarmed; fourth segment with small denticle at inner distal corner; terminal claw as long as fourth segment, with 1 small denticle proximally on inner margin.

Legs 1-4 consisting of protopod, exopod and endopod; protopods unarmed; exopods incompletely demarcated from protopod; endopods represented by broad protuberance. Exopod of leg 1 ( Fig. 98B ) armed with 1 seta and 4 simple spines. Exopod of leg 2 ( Fig. 98C ) armed with 1 seta and 3 simple spines. Legs 3 and 4 armed as leg 2.

Leg 5 ( Fig. 98D ) as conical tubercle, wider than long, bearing 1 proximal and 2 distal setae. Leg 6 ( Fig. 98E ) represented by 1 spinule and 3 spiniform processes on genital operculum; 9 small internal denticles present near leg 6.

Male. Unknown.

Remarks. Five species of eaplçstçma are now known to have 6 large lobes along the posterior margin of the labrum, as in e. latẚcaudatum sp. nov. They are e. banyulensẚs, e. kẚmẚ, e. eruca, e. pẚngue sp. nov., and e. vanuatuense sp. nov. Of these species, only in e. eruca are the 2 lateral lobes on each side of the labrum fused at base ( Ooishi & O’Reilly, 2004) as in e. latẚcaudatum sp. nov. eaplçstçma latẚcaudatum sp. nov. differs from e. eruca in having 1 spine plus 1 seta on the caudal ramus (vs. 2 spines and 1 seta in e. eruca), 3 spines plus 1 seta on the exopod of legs 3 and 4 (vs. 2 spines plus 1 seta in e. eruca), and a small leg 5 (vs. large leg 5, about 1.2 times longer than wide in e. eruca according to Ooishi & O’Reilly, 2004).

In e. latẚcaudatum sp. nov. the exopod of leg 1 is armed with 4 spines plus 1 seta and the exopods of legs 2-4 are each armed with 3 spines plus 1 seta. This combination of armature is shared with e. brevẚcauda (Canu, 1886), e. kẚmẚ, e. setẚferum Ooishi & Illg, 1977, and e. vanuatuense sp. nov., but, e. latẚcaudatum sp. nov. can be distinguished from these congeners by the different form of the labrum as mentioned above and by the differing armature of caudal ramus, which bears 2 armature elements (1 spine plus 1 seta) in contrast to 3 or more armature elements in these other four congeneric species.

Figures

FIG. 97. eaplçstçma latẚcaudatum sp. nov., female.A, habitus, dorsal; B, habitus, right; C, cephalic region, dorsal; D, cephalic region, ventral; E, genitoabdomen, dorsal; F, caudal rami, ventral; G, antennule; H, antenna; I, labrum and mandibles. Scale bars: A, B, 0.2 mm; C, D, E, 0.05 mm; F-I, 0.02 mm.

FIG. 98. eaplçstçma latẚcaudatum sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 5; E, genital aperture. Scale bars: A-C, E, 0.02 mm; D, 0.05 mm.