Hamistyelicola monniotorum, 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 : 25-28

Hamistyelicola monniotorum gen. et sp. nov.

( Figs. 12 , 13 )

Type material. Holotype ♀ (MNHN-IU-2018-1944, dissected and mounted on a slide) from myura gangelẚçn (Savigny, 1816); Ibo, Mozambique, AURACEA 1995 cruise, depth 0 - 20 m, Monniot coll., November 1995.

Etymology. The name of this new species is dedicated to Drs. Claude and Françoise Monniot who collected the copepod material studied in the present work.

Description of female. Body ( Fig. 12A ) slender, cylindrical, and distinctly segmented. Body length 2.83 mm; maximum body width 500 μm across third pedigerous somite. Prosome consisting of cephalosome and 4 pedigerous somites, occupying 44% of body length. Urosome 6-segmented, but articulation indistinct between fifth pedigerous somite and genital somite. Genital somite much shorter than first abdominal somite; genital aperture positioned dorsally. Four abdominal somites 335×269, 388×246, 299×201, and 132×166 μm, respectively; penultimate abdominal somite ornamented with numerous minute spinules dorsally and ventrally along posterior margin ( Fig. 12B ). Caudal rami ( Fig. 12B ) widely separated from each other, slightly divergent; each ramus about 4 times longer than wide (177×44 μm), gradually narrowing distally: armed with 6 small setae; outer and subdistal dorsal setae positioned at 53% and 80% of ramus length, respectively; largest of 4 distal setae 67 μm long, longer than proximal width of ramus, all other setae shorter than proximal width of ramus.

Rostrum absent. Antennule ( Fig. 12C ) 7-segmented, gradually narrowing distally; armature formula 4, 6, 5, 3, 3, 3, and 9+2 aesthetascs; first segment subdivided on one surface into 2 parts each bearing 2 setae; some of shorter setae on third to fifth segments finely spinulose unilaterally. Antenna ( Fig. 12D ) 3-segmented, consisting of coxbasis and 2-segmented endopod; coxobasis about twice as long as wide and armed with 1 spine distally (52 μm long); first endopodal segment distinctly shorter than coxobasis, armed with 1 spine (32 μm long) near middle and ornamented with several rows of fine spinules; second endopodal segment 3.0 times longer than wide (75×25 μm), armed with terminal claw, 2 spiniform setae on anterior (inner) margin, and 1 subdistal and 2 distal setae; ornamented with several rows of fine spinules; terminal claw small, less than half length of second endopodal segment.

Labrum weak, flexible, easily destroyed. Mandible (Fig, 12E) consisting of coxa and palp; coxal gnathobase bearing 4 major teeth on medial margin and 2 denticles and row of spinules on proximal margin; palp unsegmented, biramous, armed with 1 large seta on tip of small exopod and 6 setae (2 medial and 4 distal) on fused basis + endopod. Maxillule ( Fig. 12F ) consisting of precoxa bearing 9 setae on arthrite and biramous palp comprising basis and articulating exopod and endopod; armed with 5 setae on basis, 2 setae on exopod, and 6 setae on endopod. Maxilla ( Fig. 12G ) consisting of syncoxa, basis, and rudimentary endopod; syncoxa broad, bearing 1 endite tipped with 3 setae; basis lacking claw, blunt at tip, bearing 4 setae (2 subdistal and 2 distal); endopod small, with 5 setae. Maxilliped ( Fig. 13A ) as tapering lobe bearing 5 setae (2 on medial margin and 3 apically).

Legs 1-4 broad, biramous with 2-segmented rami ( Fig. 13 B-D); coxa lacking inner seta; outer seta on basis large; spines on rami distinct, but setae lacking from both rami of legs 1-4. Second segment of leg 1 endopod ( Fig. 13B ) quadrilobate along distal margin, all these lobes marginally spinulose. Second (distal) segment of exopod of leg 2-4 transformed to large, powerful hook ( Fig. 13C, D ). Second endopodal segment of legs 2-4 bearing longitudinal groove receiving exopodal hook and 2 horizontal rows of spinules on posterior surface. First endopodal segment of leg 4 bearing inner spine, but this spine absent in legs 1-3. Armature formula for legs 1-4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-0; II, I, II	0-0; IV
Legs 2 & 3	0-0	1-0	I-0; hook	0-0; II, II, II
Leg 4	0-0	1-0	I-0; hook	0-1; II, II, I

Leg 5 ( Fig. 13E ) consisting of protopod and small exopod; protopod lamellate, 252×252 μm, slightly oblong, with 1 seta distally; exopod 1.15 times longer than wide (54×47 μm), bearing 4 large and 2 small setae: lengths of large setae 280, 457, 485, and 308 μm long, respectively, from ventral to dorsal; 2 small setae 39 and 67 μm. Leg 6 ( Fig. 13F ) represented by 3 teeth on genital operculum.

Male. Unknown.

Remarks. eamẚstyelẚcçla mçnnẚçtçrum gen. et sp. nov. is distinguishable from e. lẚghtẚ (Illg & Dudley, 1980) comb. nov. as follows: (1) a small tubercle is present at the distal border of the anal somite (near the base of the caudal ramus), as figured by Illg & Dudley (1980) in the original description of e. lẚghtẚ comb. nov., but is absent in e. mçnnẚçtçrum gen. et sp. nov.; (2) the exopod and endopod of the maxillule are fused with the basis in e. lẚghtẚ, but distinctly articulated from the basis in e. mçnnẚçtçrum gen. et sp. nov.; (3) the maxilliped is armed with 4 setae in e. lẚghtẚ comb. nov., but with 5 setae in e. mçnnẚçtçrum gen. et sp. nov.; (4) the second exopodal segment of leg 1 is armed with 6 spines in e. lẚghtẚ comb. nov., but with 5 spines in e. mçnnẚçtçrum gen. et sp. nov.; and (5) the first endopodal segment of legs 2 and 3 bears an inner spine in e. lẚghtẚ comb. nov., but this spine is absent in e. mçnnẚçtçrum gen. et sp. nov.

Figures

FIG. 12. eamẚstyelẚcçla mçnnẚçtçrum gen. et sp. nov., female. A, habitus, dorsal; B, distal part of urosome, dorsal; C, antennule; D, antenna; E, mandible; F, maxillule; G, maxilla. Scale bars: A, 0.2 mm; B, 0.1 mm; C-G, 0.05 mm.

FIG. 13. eamẚstyelẚcçla mçnnẚçtçrum gen. et sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 4; E, leg 5; F, genital aperture. Scale bars: A-D, F, 0.02 mm; E, 0.1 mm.