Haplostomella multinodosa, 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 : 182

Haplostomella multinodosa sp. nov.

( Figs. 117 , 118 )

Type material. Holotype ♀ (MNHN-IU-2014-21531) and 1 ♀ paratype (MNHN-IU-2014-17392, dissected) from oẚtterella rubra Abbott & Trason, 1968; British Columbia, Canada, seapool rocks (48°49’N, 125°12’15”W), depth 40 m, Pennachetti coll., date unknown.

Etymology. The specific name is derived from the Latin mult (=many) and nçd (=swelling), and alludes to the presence of multiple interpodal tubercles associated with legs 1-4.

Description of female. Body ( Fig. 117A ) eruciform, unsegmented, slightly curved dorsally; body length 1.85 mm; maximum width 429 μm (in middle). Anterior part of body tapering anteriorly; cephalosome partially defined by posterolateral margins of cephalic shield. Metasomal region lacking any division, with 5 pairs semicircular dorsolateral folds, each pair located at level of legs 1-5, respectively: last pair of folds smaller than anterior 4 pairs. Genitoabdomen ( Fig. 117B ) short, occupying less than 20% of body length, unsegmented, not demarcated from metasome, strongly tapering; genital apertures ( Fig. 118D ) large, positioned dorsolaterally; genital operculum bearing 3 teeth distally and row of 4 denticles on ventral side. Caudal ramus ( Fig. 117C ) 2.0 times longer than wide (40×20 μm), gradually narrowing distally; armed with 5 setae (1 on outer margin, 1 subdistal dorsal, and 3 distal); seta on outer margin smaller than other caudal setae and positioned at 65% length of ramus. Egg sac ( Fig. 117D ) about 1.57× 0.41 mm, containing multiseriate eggs; each egg about 180 μm in diameter.

Rostrum absent. Antennule ( Fig. 117E ) about 85 μm long, unsegmented, with traces of 3 weak articulations along posterior side; armed with 15 setae (3 distal setae larger than others). Antenna ( Fig. 117F ) broad, 3-segment- ed; first segment unarmed; second segment wider than long, with short outer and longer inner margins, and with 1 seta at inner distal corner; third segment 1.5 times longer than wide, with 1 setiform process, 2 setae (including very small one) and 1 spinulose lobe.

Labrum ( Fig. 117G ) much wider than long, unornamented, with concave posterior margin. Mandible ( Fig. 117H ) consisting of segment plus strong, straight distal spine bearing 1 row of spinules distally. Maxillule absent. Maxilla ( Fig. 117I ) unsegmented, but divisible into broad proximal and narrower distal parts; armed with 2 setae (1 apical and 1 subapical). Maxilliped ( Fig. 117J ) broad, 2-segmented; proximal segment very broad, unarmed; distal segment with several patches of minute spinules on posterior surface ( Fig. 117K ), bluntly protruded mediodistal corner, and 1 acutely pointed spine on anteromedial surface; terminal claw with bicuspid tip.

Leg 1 ( Fig. 117L ) consisting of protopod, exopod, and endopod. Protopod bearing 1 small seta on outer margin, 1 short tubercle on posterior margin between rami, and 4 tubercles at inner distal corner. Exopod with bifurcate anterior lobe and rounded posterior lobe lacking distal seta. Endopod wider than long, with 1 large tubercle on anterior surface. Ventral lateral surface of body lateral to leg 1 bearing 1 tubercle. Ventral surface of body between left and right legs 1 bearing 10 rounded interpodal tubercles (replacing intercoxal plate). Leg 2 ( Fig. 118A ) similar to leg 1, except bearing 2 distal tubercles on endopod (large outer and small inner). Leg 3 same as leg 2. Leg 4 ( Fig. 118B ) similar to leg 2, except bearing 9 interpodal tubercles and 2 small tubercles at inner distal corner of endopod.

Leg 5 ( Fig. 118C ) as tapering, rudimentary lobe, wider than long, tipped with 2 small setae.

Male. Unknown.

Remarks. eaplçstçmella multẚnçdçsa sp. nov. is a very distinctive species, readily distinguishable from all of its congeners by the possession of the characteristic, multiple interpodal tubercles between left and right members of legs 1-4 of the female. These can be observed without dissection and it is likely these tubercles are derived from the transformed intercoxal plate. Tubercles are also present at the inner distal corner of protopods (invariably 4) and on the endopods (1 on leg 1 and 2 on legs 2-4). As additional diagnostic features of the new species, the ventral body surface lateral to each of legs 1-4 bears a single tubercle (a feature shared with e. unẚserẚata sp. nov.), the mandible bears a strong spine, and the body is unsegmented, lacking any trace of segmentation.

Figures

FIG. 117. eaplçstçmella multẚnçdçsa sp. nov., female. A, habitus, right; B, genitoabdomen, dorsal; C, caudal rami, dorsal; D, egg sac; E, antennule; F, antenna; G, labrum; H, mandible; I, maxilla; J, maxilliped; K distal segment of maxilliped, posterior; L, leg 1. Scale bars: A, 0.2 mm; B, 0.1 mm; C, E-L, 0.02 mm; D, 0.5 mm.

FIG. 118. eaplçstçmella multẚnçdçsa sp. nov., female. A, leg 2; B, leg 4; C, leg 5; D, genital aperture. Scale bars: A-C, 0.02 mm; D, 0.05 mm.