Haplostomella binodosa, 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 : 184-186

Haplostomella binodosa sp. nov.

( Fig. 119 )

Type material. Holotype ♀ (MNHN-IU-2014-21532), 5 ♀♀ paratypes (MNHN-IU-2014-21533), and 2 ♀♀ para- types (dissected, MNHN-IU-2014-17393) from Cystçdytes rçseçlus Hartmeyer, 1912 (MNHN-IT-2008-2602 = MNHN A3 / CYS/4 ); Dakar, Senegal, Stn 17, dredge, I.F.A.N. coll., 21 January 1941.

Etymology. The specific name is derived from Latin bẚ (=two) and nçdus (swelling) and refers to the presence of double tubercles on the ventral body surface lateral to legs 1-4.

Description of female. Body ( Fig. 119A ) eruciform, relatively small, curved dorsally, with 4 pairs of dorsolateral folds, 1 each at level of legs 1-4. Body length 1.01 mm; maximum width 0.21 mm. Ventral surface of body bearing 4 short, blunt protrusions, between left and right members of each leg pair ( Fig. 119A ). Cephalosome defined from metasomal region by posterolateral margins of cephalic shield. Genitoabdomen not defined from metasomal region; genital apertures large, positioned dorsolaterally; genital operculum ( Fig. 119M ) bearing 3 teeth along distal border and 1 palm-like element on ventral side bearing 5 digits. Abdomen defined from genital region only by weak constriction, unsegmented but with slight constriction in middle; dorsoposterior region of abdomen bearing row of minute spinules on each side of anal slit ( Fig. 119C ). Caudal ramus ( Fig. 119C ) about 2.3 times longer than wide (36×16 μm), with 1 outer and 4 distal setae; outer seta positioned at 55% of ramus length.

Rostrum absent. Antennule ( Fig. 119D ) stout, unsegmented, almost as long as wide, with 5 setae (including 1 large seta) on anterior side and 7 setae (including 2 larger setae) on distal margin.Antenna ( Fig. 119E ) incompletely 2-segmented; proximal segment bearing 1 seta at inner distal corner; distal segment short, slightly longer than wide, with 1 blunt process, 1 leaf-like lobe, and apical seta.

Labrum ( Fig. 119F ) with concave posterior margin and protruded, unequally bilobed posterolateral corners. Mandible ( Fig. 119G ) consisting of short, lobate segment and recurved, hook-like distal spine bearing few small spinules distally. Maxillule absent. Maxilla ( Fig. 119H ) incompletely 2-segmented; broad proximal segment unarmed; narrower distal segment tipped with 1 seta. Maxilliped ( Fig. 119I ) broad, 2-segmented; proximal segment much broader than long, unarmed; distal segment as long as wide, bearing mediodistal protrusion and medial spine; terminal claw with transverse unsclerotized region in middle, representing trace of articulation between endopod and claw; with bicuspid tip.

Leg 1 ( Fig. 119J ) with broad protopod bearing 1 seta on outer margin, 1 large tubercle at inner distal corner, and several rows of minute spinules on anterior surface. Exopod bilobed; anterior lobe claw-like, bicuspid at tip; posterior lobe tipped with 1 setule. Endopod shorter and narrower than exopod, distinctly articulated from protopod, unornamented, with rounded distal margin. Ventral surface of body lateral to leg 1 bearing 2 globular tubercles. Leg 2 ( Fig. 119K ) similar to leg 1, but inner distal tubercle on protopod bilobed, and endopod broader and weakly bilobed. Legs 3 and 4 same as leg 2.

Leg 5 ( Fig. 119L ) rudimentary, as small lobe tipped with 2 setae.

Male. Unknown.

Remarks. Three major diagnostic features of eK bẚnçdçsa sp. nov. differentiate it from its congeners, as follows: (1) the distal element of the mandible is a hook-like, recurved spine; (2) the inner distal corner of the protopod of legs 1-4 bears a tubercle which is simple in leg 1, but bilobed in legs 2-4; and (3) legs 1-4 are accompanied by a pair of tubercles positioned on the ventrolateral surface of body lateral to each leg. The first of these features was previously recorded only in e. çceanẚca. The second feature, the inner distal tubercle or protrusion on the protopod of legs 1-4 has been recorded in several species of eaplçstçmella, but only e. unẚserẚata sp. nov. is comparable with e. bẚnçdçsa sp. nov. in sharing a small, clearly defined tubercle (in other species the protrusion is large and not clearly defined from the protopod). The third diagnostic feature, the number of tubercle(s) on the ventral surface lateral to legs 1-4 is variable according to species and has been recorded or illustrated as 4 in e. australẚensẚs, e. dẚstẚncta, and e. halçcynthẚae; 3 in e. çceanẚca; 2 or 3 in e. ççẚshẚae sp. nov., and 1 in e. unẚserẚata sp. nov. and e. multẚnçdçsa sp. nov. Therefore, the new species can be distinguished from its congeners by the combination of the above three diagnostic features.

Figures

FIG. 119. eaplçstçmella bẚnçdçsa sp. nov., female. A, habitus, right; B, genitoabdomen, dorsal; C, caudal rami, dorsal; D, antennule; E, antenna; F, labrum; G, mandible; H, maxilla; I, maxilliped; J, leg 1; K, leg 2; L, leg 5; M, genital aperture. Scale bars: A, 0.1 mm; B, 0.05 mm; C, 0.02 mm; D-M, 0.01 mm.