Haplostoma pingue, 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 : 145-149

Haplostoma pingue sp. nov.

( Figs. 94 , 95 )

Type material. Holotype ♀ (MNHN-IU-2018-1995, dissected and mounted on a slide) from Tr ẚdẚdemnum sp.; SW Cape, Republic of South Africa, depth 0 m (intertidal), 05 February 1996.

Etymology. The specific name is derived from the Latin pẚngu meaning “fatty”, referring to the stout body.

Description of female. Body ( Fig. 94A ) eruciform, slightly curved dorsally, consisting of fleshy anterior part and small genitoabdomen. Body length 2.08 mm; maximum width of body 790 μm across last metasomite. Anterior part of body strongly tapering anteriorly, divisible by constrictions into 5 somites comprising cephalosome and 4 metasomites; last metasomite compound, representing fused fourth and fifth pedigerous somites. Genitoabdomen ( Fig. 94B ) small, 215×277 μm, occupying about 10% of body length, 2-segmented; anterior somite containing geni- tal apparatus, strongly tapering posteriorly with transverse strip of sclerotization on dorsal surface ( Fig. 94C ); posterior somite (free abdomen) ( Fig. 94C ) clearly defined from anterior somite, wider than long. Caudal ramus ( Fig. 94C, D ) tapering, directed posteroventrally, 1.54 times longer than wide (40×26 μm); armed with 2 distal spines and 1 dorsal plus 2 lateral setae; proximal lateral seta small, spinule-like. Egg sac ( Fig. 94E ) stringy, 6.28×0.2 μm, much longer than body, containing 4 or 5 rows of eggs.

Rostrum ( Fig. 94F ) as small, sclerotized protuberance.Antennule ( Fig. 94G ) indistinctly 2-segmented; proximal segment swollen, subdivided by anterior partial suture line, with 4 broad setae (distal seta inserted on lobe); distal segment obscurely articulated from proximal segment, much smaller; armed with 11 setae and 1 aesthetasc.Antenna ( Fig. 94H ) 2-segmented; proximal segment unarmed; distal segment 1.4 times longer than proximal, armed with 4 simple spines along distal half of segment.

Labrum ( Fig. 95A ) with 6 tapering lobes along posterior margin; these labral lobes slightly longer than wide, 2 medial lobes each with partial subdivision at distal third; second outer lobes slightly longer than other 4. Mandible ( Figs. 94F , 95A ) as small lobe tipped with 2 setae; inner seta thicker than outer. Maxillule and maxilla absent. Maxilliped ( Fig. 95B ) consisting of 4 segments plus terminal claw; first segment much broader than long, unarmed; second segment about 1.3 times longer than wide, bearing 2 equal, small setae on medial side; third and fourth segments short and unarmed; terminal claw stout, unequally bifurcate.

Leg 1 ( Fig. 95C ) consisting of protopod and exopod; protopod unarmed, with broad inner distal protuberance representing endopod; exopod clearly articulated from protopod, armed with 1 seta and 4 simple spines. Legs 2-4 armed and shaped as in leg 1.

Leg 5 ( Fig. 95D ) conical, as long as wide, directed posterodorsally, with short dorsal and long ventral margins; armed with 3 small setae (1 proximal and 2 distal). Leg 6 ( Fig. 95E ) represented by 1 small spine, 1 setule, and 5 (1 larger and 4 smaller) spiniform processes on genital operculum; 4 internal spiniform elements present near leg 6.

Male. Unknown.

Remarks. eaplçstçma pẚngue sp. nov. possesses six large lobes along the posterior margin of the labrum. This derived feature is shared with e. banyulensẚs (Brément, 1909), e. eruca (Norman, 1869), and e. kẚmẚ Seo & Lee, 2001. The first two of these species were redescribed by Ooishi (2004a) and Ooishi & O’Reilly (2004), respectively. These four species can be readily distinguished from one another by the different armature of the caudal rami; the armature formulae of the caudal rami are: II+3 (2 spines and 3 setae) in eK pẚngue sp. nov., III+ 2 in e. banyulensẚsI I+ 2 in e. kẚmẚ, and II+ 1 in e. eruca. These species also differ in the armature patterns of the exopods of legs 1-4.

The exopods of legs 1-4 of e. pẚngue sp. nov. are all armed with 4 spines and 1 seta (the combination 5, 5, 5, and 5). Only e. ambẚguum Ooishi & Illg, 1977 is known to share this armature combination with e. pẚngue sp. nov., however, e. ambẚguum differs from e. pẚngue sp. nov. in having only 4 weak lobes on the posterior margin of the labrum, 1 spine and 3 setae (formula I+3) on the caudal ramus, an outer seta on the protopod of legs 1-4, and in lacking a free abdomen.

Figures

FIG. 94. eaplçstçma pẚngue sp. nov., female.A, habitus, right; B, posterior end of body, dorsal; C, abdomen, dorsal; D, caudal ramus, lateral; E, egg sac; F, cephalic appendages ẚn sẚtu, ventral; G, antennule; H, antenna. Scale bars: A, E, 0.5 mm; B, 0.2 mm; C, D, G, H, 0.02 mm; F, 0.05 mm.

FIG. 95. eaplçstçma pẚngue sp. nov., female. A, labrum and mandibles; B, maxilliped; C, leg 1; D, leg 5; E, genital aperture. Scale bars: A-C, E, 0.02 mm; D, 0.1 mm.