Bonnierilla cheliphora, Kim & Boxshall, 2020

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 264-269

Bonnierilla cheliphora sp. nov.

( Figs. 178 , 179 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21286 ) , paratype (intact ♀, MNHN-IU-2014-21287), and dissectedparatype (♀, figured) from Herdmania momus (Savigny, 1816) , Canal Woodin, New Caledonia, depth 32 m, Monniot coll., 12 March 1987.

Additionalmaterial. 2 ♀♀ (MNHN-IU-2018-1841) from H. momus, Récif Néokumbi , New Caledonia, 1987.

Etymology. The specific name is derived from the Greek chel (claw) and phor (carry), referring to the presence of a claw on the caudal ramus.

Descriptionoffemale.Body( Fig.178A )compressed; body length 2.05 mm. Cephalosome well-defined from metasome; metasome of unexpanded, dissected specimen ( Fig. 178A ) 4-segmented, but unsegmented in swollen specimen. Fifth pedigerous somite fused with metasome. Freeurosome ( Fig. 178B ) 5-segmented: genitalsomite very short, 77×327 μm; abdominal somites gradually shorter and narrower towards posterior; 273×336, 227×295, 127×232, and 90×177 μm, respectively. Anal somite distinctly shorter than third abdominal somite. Caudalramus ( Fig. 178C ) slender, curved, gradually narrowing distally, about 4.7 times longer than wide (227×48 μm): armed with 5 setae and 1 claw (2 setae at mid-length and 3 setae+1 claw distally); two middle setae located at 50 and 55% of ramus length; distal claw articulated at base, shortand conical ( Fig. 178D ); all setae small, shorter than maximum width of ramus.

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; III, I, 4	0-1; 0-1; 1, 2, 2
Leg 2	0-0	1-0	0-1; 0-1; I, I, 5	0-1; 0-2; 1, 2, 3
Leg 3	0-1	1-0	0-1; 0-1; I, I, 5	0-1; 0-2; 1, 2, 3
Leg 4	0-1	1-0	0-0; 0-1; I, I, 5	0-1; 0-2; 1, 2, 2

Rostrum ( Fig. 178E ) about twice as wide as long (80×156 μm), semicircular, with rounded distal margin. Antennule ( Fig. 178F ) 8-segmented; armatureformula 3, 15+spine, 8, 5, 3, 2, 3, and 7+aesthetasc; first and second segments much broader than distal segments; all setae naked. Antenna ( Fig. 178G ) slender; coxa unarmed; basis 2.3 timeslongerthan wide, with 1 smallseta distally; first endopodal segment 1.5 times longer than wide, with 1 small seta subdistally; compound distal segment about 4.6 times longer than wide (120×26 μm) and 1.5 times longer than first; armed with 9 setae (distal 3 blunt at tip) plus terminal claw, less than half length of segment.

Labrum ( Fig. 178H ) ornamented with setules on both sides of posterior margin and spinules in middle. Mandible ( Fig. 178I ) with 5 teeth on cutting margin of coxa; basiswith 1 seta, 5 setae on exopod, 4 on first endopodal segment and 9 on second; distal outer seta on exopod about two-thirds as long as other 4 setae on exopod. Maxillule ( Fig. 178J ) with very broad, conical setaon coxal endite, otherwise similarto B. tenuipedis sp. nov. described above. Maxilla ( Fig. 178K ) also as in B. tenuipedis sp. nov. Maxilliped ( Fig. 179A ) distinctly 2-segmented with 10 setae on first segment and 2 setae on second.

Legs 1–4 ( Fig. 179 B-E) with 3-segmented rami. Inner coxal seta absent in legs 1 and 2, but present in legs 3 and 4. Outer seta on basis large, longer than exopod in leg 1, but small in legs 2–4. Inner distal spine basis of leg 1 extending beyond distal border of first endopodal segment, spinulose along inner margin. Third endopodal segment of leg 1 bearing 5 setae. Exopod 1.5 times longer than endopod in leg 1, about 1.9 times longer in legs 2 and 3, and twice as long in leg 4. In legs 2–4 first exopodal segment elongate, distinctly longerthan second and third segments combined, 3.7 times longer than wide in leg 2, 4.1 times longer in leg 3, and 4.3 times longer in leg 4. Inner setae on exopods of legs 2–4 small and naked. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 179F ) 2-segmented; protopod short, with 1 nakedsetaatouterdistalcornerand rowof spinulesalong innerdistal border; exopod elongate, 5.3 times longer than wide (170×32 μm), with straight sides but narrowing slightly towards tip; armed with 2 very unequal setae distally and with 4 rows of spinules on inner surface.

Male. Unknown.

Remarks. This new species is characterised by the possession of a short, conical claw on the caudal ramus, which represents a transformed seta. This caudal claw has not been recorded before, except in B. armata , in which the presence of a spine in distal part of the caudal ramus was mentioned by Schellenberg (1922). Bonnierilla armata differs from B. cheliphora sp. nov. in various characters: B. armata lacks an inner coxal seta in all biramous swimming legs, and there is no inner distal spine on the basis of leg 1. In contrast inner coxal setae are present inlegs 3 and 4 of the new species and the inner spine is present on the basis of leg 1. In addition, the second segment of the maxilliped bears only a single seta in B. armata compared to 2 setae in B. cheliphora sp. nov.

Figures

FIGURE 178. Bonnierilla cheliphora sp. nov., female. A, habitus, right; B, urosome, ventral; C, caudal ramus; D, distal part of caudal ramus; E, rostrum; F, antennule; G, antenna; H, labrum; I, mandible; J, maxillule; K, maxilla. Scale bars: A, B, 0.2 mm; C, E–K, 0.05 mm; D, 0.02 mm.

FIGURE 179. Bonnierilla cheliphora sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 3; E, leg 4; F, leg 5. Scale bars: 0.05 mm.