Bathycuma coremium, Corbera, 2008

Corbera, Jordi, 2008, Deep-sea Bodotriidae (Crustacea: Cumacea) from New Caledonia, Fiji and Indonesia, Zoological Journal of the Linnean Society 152 (2), pp. 227-254 : 251-253

BATHYCUMA COREMIUM SP. NOV. ( FIGS 22 , 23 )

Type material: Holotype: adult male, New Caledonia, BIOCAL, stn CP72, 22°09.02′S, 167°33.18′E, 2100– 2110 m, 4.ix.1985 (MNHN-Cu1101) ; Paratype: stn CP75, 22°18.65′S, 167°23.30′E, 825–860 m, 5.ix.1985,

1 preadult male without last 3 pleonites partially dissected in one slide (MNHN-Cu1102).

Diagnosis: Mid-dorsal line of carapace serrate on its anterior half, eyelobe reaching near the pseudorostral tip. Pleon without carinae. Distal process of maxilliped 3 not reaching the end of merus. Uropod rami of the same length and longer than peduncle; article 1 of endopod slightly longer than article 2.

Description: Adult male, 9.4 mm total length. Carapace ( Fig. 22A ) one-quarter total length, mid-dorsal carina with a paired row of teeth on its anterior half. Pseudorostral lobes meeting in front of the eyelobe, which is rounded and reach beyond half length of pseudorostrum lobes. Antennal notch shallow, anterolateral angle rounded (acute and with serration on the lateral margin in the preadult male; Fig. 22B ). Pleonite 6 produced between the uropods.

Antennule ( Fig. 22C ), peduncle article 1 the longest; article 3 longer than article 2; main flagellum 2-articulate, article 1 expanded at base and with a brush of sensory setae on the expansion; accessory flagellum rudimentary covered by sensory setae. Right mandible ( Fig. 22D ) with 16 setae between pars incisiva and pars molaris. Maxillule ( Fig. 22E ) palp with two unequal filaments, inner endite with five setae, three simple, one trifid and one serrulate. Maxilla ( Fig. 22F ), with simple and serrulate setae.

Maxilliped 1 ( Fig. 22G ) basis with seven plumose setae and one plumoserrate seta on inner margin, distally produced reaching carpus; carpus with seven hand-like flattened setae on the inner margin; propodus with two setae on distal inner corner. Maxilliped 2 ( Fig. 22H ) basis longer than rest of appendage, with three long pappose setae distally; merus with a long pappose seta on inner margin and a shorter one on distal outer corner; carpus longer than merus, with a long pappose seta on distal margin; propodus shorter than carpus, with three simple setae on distal inner corner and one pappose seta on outer corner. Maxilliped 3 ( Fig. 23A ), basis more than twice as long as rest of appendage, expanded distally reaching half length of merus, with three plumose setae on inner margin and six setae on inner margin of process, which has some teeth; merus with a plumose seta and a tooth on distal outer corner; carpus longer than merus, with two plumose setae on inner margin and one on distal outer corner. Pereopod 1 all articles lost except the basis in both specimens. Pereopod 2 ( Fig. 23B ), basis shorter than rest of appendage, with a simple seta on distal lower corner; ischium very short; merus longer than carpus, the last has three simple setae on distal lower corner; dactylus more than four times as long as propodus, with seven cuspidate setae on lower margin and four terminally. Pereopod 3 ( Fig. 23C ) basis longer than rest of appendage; ischium with a long simple seta; merus longer than ischium and shorter than carpus, with a long simple seta; carpus with four long simple setae on distal corner; propodus with a long simple seta on distal corner. Pereopod 4 ( Fig. 23D ), basis shorter than rest of appendage; merus longer than ischium and shorter than carpus; carpus with three long simple setae on distal corner; propodus with a long simple seta on distal corner. Pereopod 5 ( Fig. 23E ), basis rather shorter than rest of appendage; carpus more than twice as long as ischium; propodus with four long simple setae on distal corner.

Uropod peduncle ( Fig. 23F ) shorter than pleonite 6, with eight simple setae of two different lengths on inner margin. Rami subequal and longer than peduncle. Endopod 2-articulate, article 1 longer than article 2, with 14 and eight simple setae on inner margin, respectively, two long and two short simple setae distally. Exopod with plumose and simple setae on inner margin and four long and one short simple setae terminally.

Etymology: From the Greek korema meaning broom, referring to the brush of sensory setae that male has on the first antenna.

Remarks: From the 14 species of the genus Bathycuma up to now known, only six have the following combination of characters: article 1 of uropod endopod longer than article 2, no carinae on the pleon somites and dorsal carina of carapace at least partially serrate. In four of them, B. capense ( Zimmer, 1921) , B. brevirostre ( Norman, 1879) , B. longirostre Calman, 1905 and B. declinatum Gamô, 1989 , the eye-lobe is obsolete, not reaching half length of pseudorostral lobes. B. granulatum Gamô, 1989 has the article 1 of uropod endopod more than twice as long as article 2 and B. elongatum Hansen, 1895 has no ischium in pereopod 2. These features are not shared by B. coremium , which moreover has the uropod endopod longer than the peduncle.

B. brevirostre is here included between the group of species having article 1 of uropod endopod longer than article 2, although this feature is not stated in this way in the keys of Day (1978) and Petrescu (1995). This is probably a mistake as Norman (1879), in the original description of Leucon brevirostris , pointed out: ‘inner branch with first segment longer than second’. Similarly, Bonnier (1896) describing Vaunthompsonia caeca (a synonym of Bathycuma brevirostris ) clearly figured article 1 as longer than 2.

Figures

Figure 22. Bathycuma coremium sp. nov., adult male holotype (A, C) and preadult male paratype (B, D–H). A, whole animal in lateral view; B, anterior half of carapace showing the serrate anterolateral margin of a preadult male; C, antenna 1; D, right mandible; E, maxilla 1; F, maxilla 2; G, maxilliped 1; H, maxilliped 2.

Figure 23. Bathycuma coremium sp. nov., adult male holotype: A, maxilliped 3; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, uropod.