Haplostomides similis, 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 : 134-136

Haplostomides similis sp. nov.

( Figs. 87 , 88 )

Type material. Holotype ♀ (MNHN-IU-2018-1987), 5 ♀♀ intact paratypes (MNHN-IU-2018-1988), and 2 ♀♀ paratypes (dissected, MNHN-IU-2014-17380) from mçlyclẚnum macrçphyllum Michaelsen, 1919; New Caledonia, Stn NC 6, Mont Dore devant Îlet Bailly, depth 0 m, Monniot coll., 20 August 1985.

Etymology. The name of the new species reflects its close similarity to e. hawaẚẚensẚs Ooishi, 1994.

Description of female. Body ( Fig. 87A ) maggot-shaped, unsegmented, curved dorsally, gradually narrowing anteriorly. Body size variable; body length 3.53 mm in largest specimen. Legs 1-4 separated by intervals of 620, 870, and 970 μm; leg 4 isolated from posterior border of body by 970 μm. Genitoabdomen ( Fig. 87B ) very small, much wider than long, not demarcated from metasome. Caudal ramus ( Fig. 87C ) articulated from genitoabdomen, tapering, about 1.3 times longer than wide (29×22 μm), armed with 1 conical distal spine, 1 subdistal dorsal seta and 1 outer lateral seta. Egg sac ( Fig. 87D ) containing 3-5 rows of eggs, 2.16× 0.43 mm in measured sample; each egg about 170 μm in diameter.

Rostrum absent, but rostral area sclerotized and ornamented with paired rows of 4 minute denticles ( Fig. 87E ). Antennule ( Fig. 87F ) indistinctly 4-segmented, with 3, 2, 2, and 8 setae on first to fourth segments, respectively; first segment much broader than distal segments; 2 setae on second segment larger than other setae. Antenna ( Fig. 87G ) 3-segmented, consisting of broad coxa and basis and narrow endopod; coxa and basis unarmed; endopod shorter than basis, 2.5 times longer than wide (30×12 μm), gradually narrowing distally, armed with distal and sub- distal spines, both spines equal in size.

Labrum simple, unornamented, with convex posterior margin ( Fig. 87E ). Mandible ( Fig. 87H ) indistinctly 2- segmented; proximal segment tapering distally, unarmed; distal segment circular, much shorter than proximal segment, armed with 3 small setae distally. Maxillule ( Fig. 87I ) 2-segmented; proximal segment (precoxa) projecting mediodistally, with 2 equal setae on subdistal medial margin; distal segment (palp) with 5 setae (3 on outer margin and 2 on distal margin). Maxilla ( Fig. 85J ) lobate with 2 small setae (1 on medial margin and 1 apically). Maxilliped ( Fig. 88A ) 4-segmented; first segment wider than long, unarmed; second segment with 1 seta at inner distal corner; short third segment unarmed; fourth segment also unarmed; terminal claw small, pointed distally.

Legs 1-4 identical in form and armature ( Fig. 88B ). Protopod with outer seta. Exopod with 1 subdistal seta and 1 bifurcate distal spine; outer branch of distal spine much smaller than inner branch. Endopod rudimentary, represent- ed by small protuberance bearing 2 minute sensilla. Leg 5 ( Fig. 88C ) represented by 2 small setae on ventrolateral surface near posterior end of metasomal region ( Fig. 87B ). Leg 6 (Fig, 88D) probably represented by 2 spiniform elements in genital region accompanied by 5 dentiform elements.

Male. Unknown.

Remarks. According to the keys to species of ealçstçmẚdes provided by Ooishi (1994) and by Marchenkov & Boxshall (2003), eK sẚmẚlẚs sp. nov. would be identified as e. hawaẚẚensẚs Ooishi, 1994, based on the shared possession of 2 spines on the antenna, 3 setae on the mandible, 7 setae on the maxillule, and 2 setae on the maxilla. However, there are several significant differences which confirm the distinct status of eK sẚmẚlẚs sp. nov., as follows: (1) the maxillule of e. hawaẚẚensẚs bears 3 setae on the proximal segment and 4 setae on the distal segment, whereas the maxillule of e. sẚmẚlẚs sp. nov. bears 2 setae on the proximal segment and 5 setae on the distal segment; (2) the exopods of legs 1-4 of e. sẚmẚlẚs sp. nov. each bear 2 spines which are fused together at the base thus appearing as a single bifurcate spine, but in e. hawaẚẚensẚs, the 2 spines are separate; (3) leg 5 of e. sẚmẚlẚs sp. nov. is represented by 2 setae, but it consists of 3 setae in e. hawaẚẚensẚs; and (4) the antennule is 4-segmented in e. sẚmẚlẚs sp. nov., although the segmentation is incomplete, but unsegmented in e. hawaẚẚensẚs.

eaplçstçmẚdes hawaẚẚensẚs was originally described as an associate of mçlyclẚnum cçnstellatum Savigny, 1816 at Hawaii ( Ooishi, 1994) and it was subsequently reported from the same host, an invasive species in the Gulf of California ( Tovar et al., 2010). The new species is associated with mçlyclẚnum macrçphyllum collected in New Caledonia.

Figures

FIG. 87. eaplçstçmẚdes sẚmẚlẚs sp. nov., female. A, habitus, right; B, genitoabdomen, dorsal; C, right caudal ramus, dorsal; D, egg sac; E, cephalic appendages ẚn sẚtu, ventral; F, antennule; G, antenna; H, mandible; I, maxillule; J, maxilla. Scale bars: A, D, 0.5 mm; B, 0.05 mm; C, E, G, J, 0.02 mm; F, H, I, 0.01 mm.

FIG. 88. eaplçstçmẚdes sẚmẚlẚs sp. nov., female. A, maxilliped; B, leg 1; C, leg 5; D, genital aperture. Scale bars: 0.02 mm.

FIG. 85. eaplçstçmẚdes scçttẚ Chatton & Harant, 1924, female. A, habitus, dorsal; B, genitoabdomen, dorsal; C, right caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, mandible; H, maxillule; I, maxilla; J, maxilliped; K, leg 5; L, genital aperture. Scale bars: A, 0.2 mm; B, 0.1 mm; C-L, 0.01 mm.