Haplostomella bilobata Kim & Boxshall 2021, sp. nov.
Creators: name: Kim, Il-Hoi
name: Boxshall, Geoff A.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Cyclopoida
Ascidicolidae
Haplostomella
Haplostomella bilobata

description: Haplostomella bilobata sp. nov.   
(Figs. 112, 113)  
 Type material. Holotype ♀ (MNHN-IU-2014-21526), 2 ♀♀ paratypes (MNHN-IU-2014-21527), and 2 ♀♀, 1 ♂ paratypes (dissected, MNHN-IU-2014-17389) from Apl ẚdẚum sp.; Kerguelen Islands, no other collection data.   
 Etymology. The specific name alludes to the presence of a pair of lobes on the labrum of the new species.   
 Description of female. Body (Fig. 112A, B) eruciform, consisting of unsegmented anterior part and short abdomen. Body length 2.04 mm; maximum width 496 μm (across region of leg 4). Anterior half of body slightly tapering anteriorly; cephalosome narrower than metasome, incompletely defined from metasome by posterolateral margins of cephalic shield. Cylindrical metasomal region incorporating leg 5, with 5 pairs of small dorsolateral folds; last pair at level of leg 5 much smaller than anterior 4 pairs. Genital somite completely fused to metasome; paired genital apertures (Fig. 112L) positioned dorsolaterally. Genital operculum bearing 3 teeth inside. Abdomen (Fig. 112C) tapering, 3-segmented, but articulation incomplete between last 2 somites. Caudal ramus (Fig. 112D) about 2.9 times longer than wide (69×24 μm), slightly longer than anal somite, with 5 subequal, naked setae (1 lateral and 4 distal); lateral seta positioned at 63% of ramus length. Egg sac (Fig. 112B) 1.40× 0.34 mm; each egg about 115 μm in diameter.   
Rostrum absent. Antennule (Fig. 112E) 100 μm long, 2-segmented; proximal segment with 9 setae; distal seg- ment small, only 17 μm long, subdivided in middle, with 5 setae and 1 short aesthetasc; all setae naked. Antenna (Fig. 112F) indistinctly 2-segmented; proximal segment unarmed; distal segment with 1 seta on inner margin, 1 short, blunt seta plus 1 lobate process subdistally, and tipped with 1 seta.  
Labrum (Fig. 112G) short and broad, characteristically with pair of large lobes on posterior margin. Mandible and maxillule absent. Maxilla (Fig. 112H) distinctly 2-segmented; broad proximal segment unarmed; distal segment shorter and narrower than proximal segment, distally armed with 2 setae; outer seta pinnate, small medial seta naked and located on tip of digitiform process of segment. Maxilliped (Fig. 112I) consisting of 2 segments plus terminal claw; proximal segment broad and unarmed; distal segment as long as wide, with short medial margin and longer outer margin, bearing 1 broad, plate-like process and 1 acute spine near mediodistal corner; terminal claw stout with bicuspid tip.  
Leg 1 (Fig. 112J) consisting of protopod, exopod, and endopod; protopod obscurely defined at medial side, with 1 seta on outer margin; exopod distally bilobed, anterior lobe claw-like, with bicuspid tip, posterior lobe tipped with 1 small seta; endopod large, semicircular, more than twice as wide as exopod, and ornamented with rows of minute spinules. Legs 2-4 same as leg 1.  
Leg 5 (Fig. 112A, K) as rudimentary lobe tipped with 2 small setae.  
 Description of male. Body (Fig. 113A) narrow, cyclopiform, clearly segmented, with distinct prosome-urosome division. Body length 809 μm. Maximum width of body 205 μm across third pedigerous somite. Prosome consisting of cephalosome and 4 pedigerous somites. Urosome (Fig. 113B) 6-segmented, consisting of fifth pedigerous somite, genital somite and 4-segmented abdomen. Genital somite as long as wide. Four abdominal somites 50× 70m 50×61, 36×50, and 23×43 μm, respectively. Caudal ramus (Fig. 113C) rectangular, 2.24 times longer than wide (38×17 μm), armed with 6 setae (1 small outer, 1 dorsal, and 4 broad distal).   
Rostrum absent. Antennule 7-segmented; armature on segments uncertain due to many setae missing. Antenna as in female. Labrum, mandible, maxillule, and maxilla absent. Maxilliped (Fig. 113D) 2-segmented; proximal segment short and unarmed; distal segment 1.5 times longer than wide, with 1 spine subdistally and 1 small lobe at mediodistal corner; terminal claw strongly curved, with bicuspid tip.  
Legs 1-4 (Fig. 113 E-H) biramous, consisting of coxa, basis, exopod, and endopod. Coxa unarmed; basis with outer seta; basis of leg 1 additionally with inner distal spine. Exopods 3-segmented in all swimming legs. Endopods 1-segmented in leg 1, but 3-segmented in legs 2-4. All setae on swimming legs geniculate proximally, and all spines fringed with broad membranes bilaterally. Endopod of leg 1 and third exopodal segment of leg 2 with bicuspid outer distal corner. Third exopodal segment of legs 3 and 4 with tricuspid outer distal corner.  
Leg 5 (Fig. 113B) represented by free exopod tipped with 2 unequal setae. Leg 6 represented by 1 seta on distolateral apex of genital operculum.  
 Remarks. Species of ealçstçmella seldom bear any lobes on the labrum in the female. The only known exception is eK magellanẚca (Chatton & Brément, 1910) in which the labrum bears 2 pairs of lobes, as illustrated by Chatton & Brément (1910). Therefore, eK bẚlçbata sp. nov. can be distinguished from all other species of the genus by the possession of a single pair of lobes on the female labrum. Other diagnostic features of the female of e. bẚlçbata sp. nov. include: (1) the abdomen is 3-segmented, a feature shared only with e. australẚensẚs Gotto, 1970; (2) the antennule is distinctly 2-segmented, which is a unique feature of the new species; (3) the mandible is absent, a feature shared only with e. reducta Ooishi & Illg, 1977; and (4) the maxilla is distinctly 2-segmented and armed with 2 setae on its distal segment, a feature shared only with e. bçrealẚs. The combination of these diagnostic features serves to characterize the new species.
description: Published as part of Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods (Cyclopoida) associated with ascidian hosts: Ascidicolidae, Buproridae, Botryllophilidae, and Enteropsidae, with descriptions of 84 new species, pp. 1-286 in Zootaxa 1 on pages 172-176, DOI: 10.11646/zootaxa.4978.1.1, http://zenodo.org/record/4820443