Cyclocaris franki, Horton & Thurston, 2014

Horton, Tammy & Thurston, Michael H., 2014, A revision of the bathyal and abyssal necrophage genus Cyclocaris Stebbing, 1888 (Crustacea: Amphipoda: Cyclocaridae) with the addition of two new species from the Atlantic Ocean, Zootaxa 3796 (3), pp. 507-527 : 518-523

Cyclocaris franki sp. nov.

( Figures 8–11 )

Cyclocaris tahitensis (not Stebbing, 1888).— Chevreux, 1903: 89–90.— Chevreux, 1935: 31, pl. 4, fig. 4.

Cyclocaris sp. Barnard & Karaman, 1991: 479. Lowry & Stoddart, 1994: 153.

Type material. Holotype: dissected female, 20.5 mm, carcass and seven slides; Sta. 56761#1, DEMAR, 30 October 2001 (bottom time 23 hours 15 minutes), 06˚ 18.68’S 10˚ 44.86’W, 2059 m, Angola Slope ; NHMUK 2014 . 459 . Allotype: adult male, 15.5 mm, same data as holotype; NHMUK 2014 . 460 . Paratypes: 39 specimens, same data as holotype; NHMUK 2014 . 461– 470.

Additional material examined. Specimens retained in the Discovery Collections, National Oceanography Centre, Southampton.

7822#7, BN 2.4, 5 March 1972, 08º 59.1’N 20º 16.3’W – 08º 59.9’N 20º 16.2’W, 1203 m, Sierra Leone Rise; 1 specimen.

56770#1, DEMAR, 1 November, 2001 (bottom time 27 hours 47 minutes), 06˚ 12.88’S 10˚47.14’W, 1850 m, Angola Slope ; 1 female specimen.

56734#1, DEMAR, 26 October 2001, (bottom time 22 hours 14 minutes), 06˚ 10.14’S 10˚ 46.62’W, 1859 m; 6 female specimens .

Etymology. The species is named in honour of the first author’s son, Frank.

Description. Holotype female, 20.5 mm. Head: exposed, deeper than long, rather short dorsally but telescoped into peraeonite 1; lateral cephalic lobe moderate, subquadrate; rostrum small. Eyes: four, red pigmented, lacking ommatidea, pigment fades in alcohol; upper, undefined elongate shape spreading towards and covered by peraeonite 1; lower, larger, in cephalic lobe but partly covered by coxa 3. Antenna 1: short, 0.12 x body; peduncular article 1 short; peduncular article 2 short, 0.3 x article 1; peduncular article 3 short, 0.3 x article 1; primary flagellum nine-articulate; accessory flagellum long, 0.5 x primary flagellum, five-articulate, article 1 as long as articles 2–5 combined; callynophore strong two-field; calceoli absent. Antenna 2: short, 1.65 x antenna 1; peduncle without brush setae, not geniculate; peduncle article 1 not greatly enlarged; peduncle article 3 short, 0.5 x article 4; articles 4 and 5 not enlarged; flagellum well developed, 22-articulate.

Mouthpart bundle: subquadrate. Epistome and upper lip: separate, rounded, weakly produced, epistome dominant. Mandible: incisor smooth, weakly convex, with two small ventral ‘teeth’; lacinia mobilis present on left mandible only, a slender peg without ornamentation; accessory setal rows with ten simple robust setae and many setules; molar a setose, proximally directed, non-triturating flap; palp attached distally; article 1 short, broader than long; article 2 slender, length 3.9 x breadth, with 14 A2 setae on distal 0.4; article 3 slender, tapering, length 4.1 x breadth, with 17 D3 setae and three E3 setae. Lower lip: outer plates gaping, setose marginally, inner lobes present, small, molar processes prominent, rounded distally. Maxilla 1: inner plate slender, with eight pappose setae along inner margin; outer plate with 11 setal-teeth in a 7/4 crown arrangement, ST1–6 weakly one-, two- or threecuspidate, ST7 simple, ST7 displaced from ST6, STA–C one-cuspidate, STD, displaced from A–C, simple; palp large, two-articulate, article 1 short, article 2 broadened with three short robust setae on tridentate apical margin, one flag seta, three subapical robust setae, and one pappose seta on dorsal margin (not figured as damaged). Maxilla 2: inner plate short, 0.67 x length of outer plate, tapering, with rows of marginal and submarginal pappose and simple setae; outer plate with marginal and apical stout and slender setae. Maxilliped: inner plate large, subtriangular, with three very small nodular spines on strongly oblique apical margin, oblique setal row strong, with eight pappose setae; outer plate large, subovate, with 14 pappose setae and three robust setae apically and laterally, and about twenty minute nodular setae on medial margin; palp large, four-articulate, article 2 slender, length 2.4 x breadth, article 3 long, slender, length 3.1 x width, dactyl well-developed, slender, with three short subterminal setae.

Gnathopod 1: simple; coxa vestigial, anterior margin straight, posterior margin convex; basis long, slender, length 5.5 x breadth, anterior margin straight, with four simple setae, posterior margin straight, with two simple setae; ischium long, length 3.4 x breadth; carpus very long, subquadrate, lacking posterior lobe, margins subparallel, length 4.2 x. breadth, 1.3 x length of propodus; propodus long, subquadrate, length 4.9 x breadth, margins weakly convergent, anterior weakly convex, posterior weakly concave, palm absent; dactylus simple, length 0.34 x propodus, with subterminal setae. Gnathopod 2: subchelate; coxa vestigial, subrectangular; basis long, slender, curved, anterior margin convex, length 5.3 x breadth; ischium long, length 4.2 x breadth; carpus very long, length 5.6 x breadth, margins subparallel, posterior margin straight, 2.0 x length of propodus; propodus subovate, length 2.9 x breadth, setulose, palm acute, weakly convex, serrate distally; dactylus inserted near middle of propodus distal margin, reaching corner of palm. Peraeopod 3: coxa large, weakly expanded, broadly rounded distally; basis weakly sinuous, margins subparallel; merus narrowly produced anterodistally, extending 0.39 x length of carpus; dactyl slender, curved, 0.43 x length of propodus. Peraeopod 4: coxa as deep as wide, posteroventral lobe short, broadly rounded; distal articles as in peraeopod 3. Peraeopods 5–7: subequal in length. Peraeopod 5: coxa unequally bilobate, posterior lobe deeper, strongly produced posteriorly; basis expanded, subrectangular, posterior margin convex, posterodistal margin broadly rounded; merus produced posterodistally, extending 0.22 x length of carpus, propodus slender, length 6.4 x breadth; dactylus slender, curved, 0.38 x length of propodus. Peraeopod 6: coxa subrectangular, expanded posteriorly; basis expanded, posterior margin convex, distally bevelled, posterodistal lobe rounded; merus slender, posterior margin weakly convex, weakly produced. Peraeopod 7: coxa posterior lobate; basis expanded, tapering distally, posterior margin convex, posterodistal lobe narrowly rounded; merus slender, weakly produced posterodistally. Gills: gnathopod 2 to peraeopod 7; peraeopod 7 gill large. Oostegites: gnathopod 2 to peraeopod 5.

Pleonites 1 to 3: not carinate. Epimeron 1: broadly rounded ventrally. Epimeron 2: subrectangular; anteroventral corner rounded, posteroventral corner with acute tooth, posterior margin sinuous, ventral margin setose. Epimeron 3: expanded distally; anteroventral corner rounded, posteroventral corner with subacute tooth, posterior margin concave, ventral margin setose. Urosome: urosomite 1 lacking rounded boss; urosomite 2 occluded dorsally; urosomite 3 produced posterolaterally, markedly concave dorsally, with strong dorsolateral flanges. Uropod 1: peduncle with 5 dorsolateral robust setae and 5 dorsomedial robust setae; inner ramus 0.68 x length of peduncle, with 2 dorsomedial setae; outer ramus as long as inner ramus, with 3 dorsolateral setae. Uropod 2: peduncle with 1 dorsomedial robust seta; inner ramus as long as peduncle, with 2 lateral and 5 medial setae; outer ramus 0.83 x inner ramus, with 2 lateral and 3 medial setae. Uropod 3: peduncle short, with 3 dorsomedial setae; rami subequal, lanceolate, with plumose setae on medial margins; inner ramus 1.7 x peduncle, with 2 lateral and 2 medial robust setae; outer ramus 2-articulate, article 2 length 0.23 x article 1 with 2 lateral and 1 medial robust setae. Telson: long, lobes tapering, length 2.3 x breadth, cleft 85%; lobes with 4 dorsolateral robust setae, apices weakly notched, lacking robust setae.

Male. Similar to female except for calceoli on both antennae and a longer callynophore.

Remarks. This species is most closely related to Cyclocaris lowryi . It can be distinguished from that species by characters of pereopods 5–7. C. franki has the basis of peraeopod 5 produced posterodistally, the basis of peraeopod 6 emarginate posterodistally, and peraeopods 5–7 with broad meral articles (length/breadth ratios 1.6, 1.7 and 2.1 respectively). In contrast, C. lowryi has the basis of peraeopod 5 broadly rounded and produced distally, the basis of peraeopod 6 convex posterodistally, and peraeopods 5–7 with narrow meral articles (length/breadth ratios 2.2, 2.7 and 2.9 respectively). C. franki can be distinguished from C. tahitensis by the lack of eyelobes and the broadly rounded posterodistal lobe of coxa 4 of the latter.

C. franki differs from C. guilelmi in having subacute triangular eyelobes and four evanescent red-pigmented ocular patches in contrast to the broadly convex anteroventral head margin and permanent yellow-brown ocular pigment covering the whole head of the latter species.

The single specimen from Monaco Station 1206 close to the Cape Verde Islands, collected at a depth of 1477 m and recorded as C. tahitensis by Chevreux (1903, 1935) belongs to this species. Chevreux noted that the only differences he could find between the Tahiti specimen ( C. tahitensis ) and his specimen were that pereopods 5–7 were more spinose and the apices of the telson were a little different.

All known material of C. franki has been obtained from baited benthic traps.

Distribution. Atlantic Ocean. Angolan continental margin, 1850–2059 m; Sierra Leone Rise, 1203 m (present material); Cape Verde Islands, 1477 m ( Chevreux, 1903, 1935).

Figures

FIGURE 8. C. franki sp. nov.: holotype; adult female, 20.5 mm, antennae and gnathopods. Paratype; adult female, 26.5 mm, habitus.

FIGURE 9. C. franki sp. nov.: holotype; adult female, 20.5 mm, mouthparts.

FIGURE 10. C. franki sp. nov.: holotype; adult female, 20.5 mm, peraeopods, uropods and telson.

FIGURE 11. C. franki sp. nov.: holotype; adult female, 20.5 mm, head. Allotype; adult male, 15.5 mm, head.