Haploniscus monoceros, Brökeland, Wiebke, 2010

Brökeland, Wiebke, 2010, Description of four new species from the Haploniscus unicornis Menzies, 1956 complex (Isopoda: Asellota: Haploniscidae), Zootaxa 2536, pp. 1-35 : 10

Haploniscus monoceros n. sp.

( Figs 6–8 )

Holotype: DIVA 2-HA549, adult male, length 1.66 mm, coll.: RV Meteor, M63/2, DIVA 2 expedition, MUC station 99, 0°37.20’ N 6°28.14’ W, 5167 m, Guinea Basin, southeast Atlantic, ZMH K- 42429.

Paratype: DIVA 2-HA234, adult male (stage VI), length 1.67 mm, coll.: RV Meteor, M63/2, DIVA 2 expedition, EBS station 89-6, 0°42.95’ N 5°31.29’ W, 5142 m, Guinea Basin, ZMH K- 42430.

Etymology. Monoceros is the Greek name of the constellation “Unicorn” and alludes to Haploniscus unicornis (Latin “single-horned”), the eponymous species of the complex.

Diagnosis. Rostrum length 0.5 head length. Pereonites 3–5 broadest, body tapering slightly anteriorly and posteriorly. Lateral margins of pleotelson tapering posteriorly, pleotelson process length 0.5 pleotelson length, 1.9 width. Pleopod 1 lateral margins tapering continuously into neck; distance basal margin–neck 0.8 total length, neck width 0.3 maximum width. Pleopod 2 endopod only slightly elongated, total length 1.3 protopod length, 6.0 width; article 2 length 3.5 article 1 length.

Description (stage VI male). Body ( Fig. 6 A–F) length 2.7 width. Head length 0.7 width. Posterior angles of pereonites 2–7 and anterior angles of pereonites 3–5 acute. Pleotelson length 0.3 body length, 0.8 width.

Antenna 1 ( Fig. 7 G) peduncular article 1 length 1.6 width, with 3 penicillate setae distally; article 2 length 1.3 article 1 length, 2.45 width, with1 simple and 4 penicillate setae distally; article 3 length 0.3 article 1 length, width 0.5 article 1 width, with 2 simple setae distally. Flagellum with 4 articles; article 1 shortest, with 2 penicillate setae; article 2 longest, about 2.8 article 1 length, with 1 aesthetasc and 1 simple seta; article 3 with 2 aesthetascs and 1 simple seta, article 4 with 3 aesthetascs (one broken off), 2 simple setae and 1 small penicillate seta.

Antenna 2 ( Fig. 7 F) peduncular article 2 with 2 simple setae; article 3 length 1.9 width, with 2 long simple setae dorsally, dorsal tooth with 2 simple setae; article 4 0.6 article 3 length, 1.1 width, with 2 simple setae distally; distal articles missing.

Pereopods ( Figs 7 A–E; 8C, D): Basis of all pereopods with 2 long simple setae ventrally; basis of pereopods 2 and 3 with 2 penicillate setae, of pereopods 4–7 with 3 penicillate setae dorsally (2 broken off on pereopod 6). Ischium with 1–2 simple setae dorsally and ventrally each. Merus with 2 setae of different length distoventrally; pereopod 1 with 4, pereopod 2 with 3, pereopods 3–7 with 2 setae distodorsally, 1 dorsal seta of pereopod 1 long and stout. Carpus with 2 or 3 simple setae ventrally; pereopods 1–6 with 1 short simple seta (broken off on pereopod 7) distodorsally, pereopods 2–7 with 1 penicillate seta (broken off on some pereopods) distodorsally. Propodus with 3–5 setae ventrally, peropods 1–3 with 1 simple seta distodorsally (broken off on remaining pereopods), pereopods 2–7 with 1 penicillate seta distodorsally. Dactylus of pereopod 1 with 5, of pereopods 2–3 with 4 and of pereopods 6–7 with 2 setae near insertion of unguis (distal propodus and dactylus missing on pereopods 4 and 5).

Pleopod 1 ( Fig. 8 A) length 0.8 pleotelson length, about 2.3 width; widest part after about 0.20 of its length.

Pleopod 2 ( Fig. 8 B) protopod length 1.9 width, with about 9 long setae along outer margin.

Pleopod 3 ( Fig. 8 E) endopod length 1.6 width. Exopod length 0.7 endopod length, 2.0 width.

Pleopod 4 ( Fig. 8 F) endopod length 2.1 width. Exopod length 0.6 endopod length, 3.1 width, plumose seta length about 1.7 exopod length.

Pleopod 5 ( Fig. 8 G) length 2.4 width.

Uropod ( Fig. 6 E) extending beyond posterior margin, not reaching tips of pleotelson processes.

Distribution. Found in the Guinea Basin, Southeast Atlantic.

Figures

FIGURE 6. Haploniscus monoceros n. sp., male paratype, ZMH K- 42430 (A, B, E) and holotype, ZMH K- 42429 (C, D, F); A, habitus, dorsal view; B, habitus, lateral view; C; head, dorsal view; D, head, lateral view; E, posterior body, ventral view; F, pleotelson process, lateral view. Scale bar 1 mm for A, B, E and 0.5 mm for C, D, F.

FIGURE 7. Haploniscus monoceros n. sp., male paratype, ZMH K- 42430; A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, antenna 2; G, antenna 1. Scale bar 0.1 mm.

FIGURE 8. Haploniscus monoceros n. sp., male holotype, ZMH K- 42430; A, pleopod 1; B, pleopod 2; C, pereopod 6; D, pereopod 7; E, pleopod 3; F, pleopod 4; G, pleopod 5. Scale bars 0.1 mm.