Botryllophilus coniorhynchus, 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 : 95-99

Botryllophilus coniorhynchus sp. nov.

( Figs. 60-62 )

Type material. Holotype ♀ (MNHN-IU-2018-1973), 3 ♀♀ paratypes (intact, MNHN-IU-2018-1974), and 2 ♀♀ paratypes (dissected, MNHN-IU-2014-17376) from Aplẚdẚum falklandẚcum Millar, 1960 (MNHN-IT-2008-386 = MNHN A1 / APL.B/532); Antarctic, Terre Adélie, CEAMARC cruise, RV “Aurore Australis”, Stn 18EV479 (66º10’S, 139º41’E), depth 402-437 m, IPEV-AAD-MNHN coll., 15 January 2008.

Etymology. The name of the new species is derived from the Greek cçnẚ (= a cone) and rhynch (= a snout), and refers to the conical rostrum.

Description of female. Body ( Fig. 60A, B ) asymmetrical, 1.15 mm long. Anterior part of body comprising cephalosome to fifth pedigerous somite, 0.73 mm long, invariably slightly curved to right side, unsegmented but with 4 weak constrictions dorsally and laterally; lateral margins parallel. Body width 0.33 mm across middle of anterior part. Posterior part of body ( Fig. 60C ) consisting of genital and 4 abdominal somites. Genital apertures positioned dorsally on genital somite. Caudal ramus ( Fig. 60D ) armed with 4 claws and 1 seta; 1 outer distal claw bluntly tipped, other claw not articulated with ramus.

Rostrum ( Fig. 61A ) distinct, conical, longer than wide (57×42 μm). Antennule ( Fig. 60E ) short, about 115 μm long, strongly tapering, with markedly broadened first and second segments; terminal segment subdivided on posterior side; armature formula 9 (3 large and 6 small), 5 (2 large and 3 small), 2 (1 large and 1 small), and 12. Left antenna ( Fig. 60F ) apparently 5-segmented, consisting of coxa, basis, and 3-segmented endopod; proximal 3 segments unarmed; second endopodal segment (fourth segment) 46×18 μm, with 2 bluntly tipped setae on inner margin; third endopodal segment 17×16 μm, with 4 (2 shorter inner and 2 longer outer) bluntly tipped setae on distal margin. Right antenna similar in size and segmentation to left antenna; 2 setae on second endopodal segment and 2 inner distal setae on third endopodal segment slightly longer than those of left antenna and distally spinulose ( Fig. 60G ); 2 outer distal setae distinctly shorter than those of left antenna.

Labrum ( Fig. 60H ) with large, semicircular posteromedian lobe. Mandible ( Fig. 60I ) with 1 bifurcate tooth and 2 shorter teeth on coxal gnathobase; palp with 2 lobes in middle of inner margin, armed with 9 setae arranged as 3, 2, 2, and 2. Maxillule ( Fig. 61B ) consisting of precoxa and palp; precoxa with 5 distinct setae on arthrite; palp 3-segmented, consisting of coxa, basis, and endopod; coxa unarmed (lacking seta of epipodite); basis with 2 setae on medial margin, 3 setae on outer margin, and setulose distal lobe; endopod articulated from basis, armed with 3 setae on distal margin. Maxilla ( Fig. 61C ) indistinctly 3-segmented and armed with 2, 4, and 3 setae on first to third segments, respectively. Maxilliped ( Fig. 62A ) 4-segmented; syncoxa large, with 1 small seta proximally on inner margin and patch of spinules subdistally on inner side; basis with 2 small isolated setae; short first endopodal segment unarmed; second endopodal segment with 2 small setules and 1 pointed inner distal process; terminal claw small, about half as long as second endopodal segment.

Legs 1-4 ( Figs. 61 D-G, 62B-E) biramous, with 1-segmented exopods and 2-segmented endopods; coxa unarmed; basis with 1 seta on outer margin. Basis of legs 1-3 with 1 prominent, spiniform process at inner distal corner and 2 to 4 spinules on distal margin near base of endopod; basis of leg 4 with 2 patches of several spinules at each inner distal corner and on distal margin. Spines on exopods of right legs 1-3 elongate. Exopods of right legs 1 and 2 armed with 1 seta (outer proximal element) and 5 spines. Numbers of spines (Roman numerals) and setae (Arabic numerals) on right and left legs 1-4 as follows:

Leg 5 ( Fig. 62F ) positioned dorsolaterally on fifth pedigerous somite, evenly tapering, 2.4 times longer than wide (140×58 μm), with 1 small seta proximally and 2 small plus 1 larger seta distally; larger distal seta longer than leg (exopodal) segment. Leg 6 ( Fig. 62G ) represented by 1 spinule and 2 spinule-like processes on genital operculum; 9 small denticle-like elements on surface adjacent to leg 6.

Male. Unknown.

Remarks. Three outstanding features serve to characterize BK cçnẚçrhynchus sp. nov. as follows: (1) the exopods of right legs 1 and 2 each carry 1 seta in addition to spines; (2) the combination of armature elements on right legs 1-4 is 6-6-6-4, and (3) the endopod of the antenna is apparently 3-segmented, the segmentation has not been recorded previously in Bçtryllçphẚlus and, as it appears incomplete, it may represent a distinct fold in the cuticle rather than a true articulation. The combination of armature elements on the exopods of left legs 1-4 (5-5-5-4) also is unusual, known previously only in B. banyulensẚs.

Figures

FIG. 60. Bçtryllçphẚlus cçnẚçrhynchus sp. nov., female. A, habitus, dorsal; B, habitus, left; C, posterior region of body, dorsal; D, caudal ramus; E, antennule; F, left antenna; G, distal part of right antenna; H, labrum; I, mandible. Scale bars: A-C, 0.1 mm; D-I, 0.02 mm.

FIG. 61. Bçtryllçphẚlus cçnẚçrhynchus sp. nov., female.A, rostrum; B, maxillule; C, maxilla; D, right leg 1; E, left leg 1; F, right leg 2; G, left leg 2. Scale bars: 0.02 mm.

FIG. 62. Bçtryllçphẚlus cçnẚçrhynchus sp. nov., female. A, maxilliped; B, right leg 3; C, left leg 3; D, right leg 4; E, left leg 4; F, leg 5; G, genital aperture. Scale bars: A-E, G, 0.02 mm; F, 0.05 mm.