Debruma deplanata, Kim & Boxshall, 2021

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods associated with Ascidian hosts (Tunicata): Intramolgidae and Lichomolgidae, with descriptions of four new genera and 13 new species, Zootaxa 5013 (1), pp. 1-75 : 13-16

Debruma deplanata sp. nov.

( Figs. 7 , 8 )

Type material. Holotype ♀ (MNHN-IU-2014-21595, dissected and mounted on a slide) from Asc ẚdẚa ornata Monniot F. & Monniot C., 2001 (MNHN-IT-2008-2621 = MNHN A3 /CYS/135); Offshore sand cay, West side of White Island , Camiguin Island, the Philippines (09°15.38´N, 124°39.12´E), depth 18 m; CRCHO 148 , Site Caminguin 4, CRRF coll., 19 April 1997.

Etymology. The specific name is derived from the Latin deplanat (meaning “flattened”) referring to the flattened body of the new species.

Description of female. Body ( Fig. 7A ) stout, dorsoventrally flattened. Body length 1.24 mm; prosome 808×555 μm, oval in dorsal view. Urosome ( Fig. 7B ) stocky, 5-segmented. Fifth pedigerous somite 182 μm wide, with minute spinules at lateral apices. Genital double-somite 204×193 μm; genital apertures located dorsolaterally about at mi- dlength of double-somite. Three free abdominal somites much shorter than wide, 48×132, 48×106, and 39×100 μm, respectively. Posteroventral margins of genital double-somite and 3 free abdominal somites fringed with crenate membrane ( Fig. 7C ). Caudal ramus very short, 36×45 μm, about 1.25 times wider than long, armed with 6 setae; setae II and VII naked; setae III and VI pinnate; setae IV and V missing. Egg sac ( Fig. 8A ) fusiform, 680×250 μm; each egg about 73 μm in diameter.

Rostrum ( Fig. 7D ) tapering. Antennule ( Fig. 7E ) 315 μm long, 7-segmented; terminal segment shortest; arma- ture formula 4, 13, 6, 3, 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc; all setae naked. Antenna ( Fig. 7F ) slender, consisting of coxobasis and 3-segmented endopod; coxobasis with 1 seta at inner distal corner; first endopodal segment longest, with 1 seta on inner margin and ornamented with fine spinules proximally and distally on outer margin; small second endopodal segment bearing 4 inner setae; third endopodal segment about 5.8 times longer than wide (121×21 μm), and ornamented with fine spinules on proximal outer margin; armed with 3 minute setae and 3 slender claws distally (2 claws longer and annulated, 1 short, non-annulated).

Labrum ( Fig. 7G ) deeply incised, with rounded posterior lobes. Mandible ( Fig. 7H ) constricted between basal part and blade; blade also constricted proximally, ornamented with spinules proximally along inner and outer margins; distal two-thirds of blade serrate along outer margin but smooth along inner margin. Maxillule ( Fig 7I ) lobate, with 1 small subdistal seta and 2 stiff distal setae directed crossways. Maxilla ( Fig. 7J ) consisting of unarmed syncoxa and basis terminating in gently curved, slender lash bearing row of spinules along convex outer margin, and armed with broad anterior seta and minute inner seta. Maxilliped ( Fig. 7K ) reduced, 2-segmented; proximal segment (syncoxa) unarmed; distal segment tapering, bluntly tipped, armed with 2 setae in middle, 1 small spine subdistally, and 2 patches (proximal and distal) of minute spinules.

Leg 1 ( Fig. 8B ), leg 2 ( Fig. 8C ) and leg 3 with 3-segmented rami. Leg 4 ( Fig. 8D ) with 3-segmented exopod and 2-segmented endopod. Inner distal margin of basis ornamented with spinules in leg 1 but with setules in legs 2–4. Leg 4 coxa with inner seta slightly expanded and naked; second endopodal segment 45×20 μm, with distal spine 48 μm long. Armature formula for legs 1–4 as follows:

Coxa Basis Exopod Endopod

Leg 1: 0-1 1-0 I-0; I-1; III, I, 4 0-1; 0-1; I, 1, 4

Leg 2: 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 3

Leg 3: 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 2

Leg 4: 0-1 1-0 I-0; I-1; II, I, 5 0-1; 0, I, 0

Leg 5 consisting of outer dorsal seta inserted on fifth pedigerous somite and free exopod; exopodal segment ( Fig. 8E ) about 1.6 times longer than wide (81×51 μm), gradually broadening distally, with hyaline fringe along inner margin; armed with 1 seta (155 μm long) and 1 broad, knife-shaped spine (67 μm long). Leg 6 ( Fig. 8F ) rep- resented by 1 pinnate seta, 1 spinulose seta and 1 small spine on genital operculum.

Male. Unknown.

Remarks. aebruma has been a monotypic genus represented only by the type species a. clavelẚnae Humes & Stock, 1973, found associated with the ascidian host Clavelẚna pẚcta (Verrill, 1900) in Bermuda ( Humes & Stock, 1973). aebruma deplanata sp. nov. differs from a. clavelẚnae as follows: (1) the body of the female is stocky (vs. slender in a. clavelẚnae); (2) the caudal ramus is wider than long (vs. 3.1 times longer than wide in a. clavelẚnae, according to Humes & Stock, 1973); (3) the third endopodal segment of the antenna is about 5.8 times longer than wide (vs. 2.8 times longer than wide in a. clavelẚnae); (4) the blade of the mandible is constricted proximally (vs. evenly attenuated in a. clavelẚnae); (5) the maxillule is armed with 3 setae (vs. armed with a single seta in a. clavelẚnae); and (5) the distal segment of the female maxilliped is tapering (vs. subdistally expanded in a. clavelẚnae). These differences are sufficient to justify the establishment of the new species.

Genus Henicoxiphium Illg & Humes, 1971

Remarks. The genus eenẚcoxẚphẚum consists of only a single species, eK redactum Illg & Humes, 1971 described as an associate of the ascidian Styela plẚcata (Lesueur, 1823) in Florida and North Carolina, USA (Illg & Humes, 1971). The most significant diagnostic feature of eenẚcoxẚphẚum is the endopod of leg 4 which is 3-segmented and the third segment is armed with a single distal spine (the armature formula for the endopod of leg 4 is 0-1; 0-1; 0, I, 0).

Figures

FIGURE 7. aebruma deplanata sp. nov., female. A, habitus, dorsal; B, urosome, dorsal; C, right side of abdomen, ventral; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule; J, maxilla; K, maxilliped. Scale bars:A, 0.2 mm; B, 0.1 mm; C, G–K, 0.02 mm; D–F, 0.05 mm.

FIGURE 8. aebruma deplanata sp. nov., female. A, egg sac; B, leg 1; C, leg 2; D, leg 4; E, exopod of leg 5; F, right genital aperture. Scale bars: A, 0.2 mm; B–F, 0.05 mm.