Haplostomella tuberculata (Chatton & Harant, 1924)

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 : 172

Haplostomella tuberculata (Chatton & Harant, 1924)

( Fig. 111 )

Material examined. 33 ♀♀ (MNHN-IU-2014-21525, 2 ♀♀ dissected) in Aplẚdẚum nçrdmannẚ Milne Edwards, 1841; Greece, Stn 486, Koukouras coll., date unknown .

Redescription of female. Body ( Fig. 111A ) eruciform, consisting of cephalosome, cylindrical metasome, and small genitoabdomen. Body length 2.36 mm, maximum width 545 μm (across anterior third): cephalosome 190×290 μm, incompletely separated from metasome, but distinctly defined by its narrowness. Metasome unsegmented, lack- ing any constriction, with 5 pairs of small dorsolateral folds (vestiges of tergites), each pair located at level of leg pair (legs 1 to 5). Genitoabdomen ( Fig. 111B, C ) tapering, unsegmented, not articulated from metasome, occupying about 16% of body length, with narrow posterior half; genital apertures positioned dorsolaterally; genital operculum large, rounded, with 3 strong denticles. Caudal rami ( Fig. 111D ) incompletely articulated from abdomen, narrowing distally, 2.64 times longer than wide (95×36 μm); armed with 4 distinct setae (3 distal and 1 dorsal) and 1 small setule located midway along outer margin.

Rostrum short with convex posterior margin. Antennule ( Fig. 111E ) incompletely 2-segmented, about 2.2 times longer than wide, bearing 16 setae; all setae characteristically small, setule-like, subequal in length. Antenna ( Fig. 111F ) indistinctly 3-segmented and curved ventrally; first segment longest but unarmed; second segment distally bearing 1 small seta and 1 row of several spinules; third segment bearing 1 subdistal and 2 distal, small setae, 1 spinulose lobate process subdistally, and patch of spinules in middle.

Labrum ( Fig. 111G ) short, unornamented, with broadly convex posterior margin. Mandible ( Fig. 111H ) 1- segmented, digitiform, with 2 weak swellings on medial margin, and tipped with 1 naked seta. Maxillule absent. Maxilla ( Fig. 111I ) 1-segmented, with 2 weak swellings on subdistal medial margin, tipped with 1 weakly pinnate seta. Maxilliped ( Fig. 111J ) robust, consisting of 2 segments plus terminal claw; proximal segment (syncoxa) much broader than long, unarmed; distal segment (basis) as long as wide, bearing 1 spine and 1 spinulose, lobate process at mediodistal corner, and ornamented with numerous minute spinules on outer (ventral) surface; terminal claw pointed distally and directed between mediodistal process and spine of distal segment.

Leg 1 ( Fig. 111K ) consisting of unsegmented protopod, exopod and endopod. Intercoxal plate absent. Protopod broad, with 1 seta on outer margin. Exopod bilobed; anterior lobe claw-like, sclerotized, pointed distally, bearing small, mammiform subdistal process; posterior lobe broader than anterior, rounded distally, tipped with 1 small setule. Unarmed endopod broader than long, broader than exopod, with slightly concave distal margin. Legs 2-4 same as leg 1.

Leg 5 ( Fig. 111B, C, L ) as small lobe tipped with 3 small, naked setae.

Male. Unknown.

Remarks. The above specimens are identified as eK tuberculata on the basis of the close agreement between these specimens and the original description of this species given by Chatton & Harant (1924a), as follows: (1) the metasome bears 5 pairs of small dorsolateral folds (vestiges of tergites); (2) the form of the genitoabdomen in lateral view is the same as illustrated in the original description; (3) the antennule is incompletely 2-segmented and armed with equally small setae; (4) the caudal ramus bears 4 distal setae; (5) the mandible and maxilla are each tipped with 1 seta; and (6) leg 5 bears 3 setae. Chatton & Harant (1924a) gave a measurement of 1.5 mm for the body length of the type specimens; this is significantly shorter than 2.36 mm for our measured specimen. This length difference can probably be explained by variation in the state of maturity of the material: Chatton & Harant (1924a) mentioned that the type specimens were immature females. In addition, we have observed that females of eaplçstçmella are highly elastic and will swell up gradually when immersed in lactic acid for study.

Figures

FIG. 111. eaplçstçmella tuberculata (Chatton & Harant, 1924), female. A, habitus, dorsal; B, posterior part of body, dorsal; C, posterior part of body, left; D, caudal rami, dorsal; E, antennule; F, antenna; G, labrum; H, mandible; I, maxilla; J, maxilliped; K, leg 1; L. leg 5. Scale bars: A, 0.2 mm; B, C, 0.1 mm; D, 0.05 mm; E-L, 0.02 mm.