Archasterope weddellensis Kornicker 1975

Archasterope weddellensis (Kornicker, 1975)

(Figs. 2–8)

1975 Empoulsenia weddellensis, new species Kornicker: 514–524, figs. 323–328.

1986 Empoulsenia weddellensis Kornicker, 1975 — Hartmann: 1986, 153.

1989 Empoulsenia weddelensis Kornicker, 1975 — Hartmann: 1989, 236 (spelling error). 1990 Empoulsenia weddellensis Kornicker, 1975 — Hartmann: 1990, 200.

1996 Archasterope weddellensis (Kornicker, 1975) —Kornicker: in Kornicker & Poore 1996, 142 (list), 143 (key).

Material (Fig. 1). R/V “Polarstern”, ANT XXII /3, PS 67, 2005:

Stat. 151-1: ZMH-K-41903—adult female (length 3.26 mm), 2 juveniles (2.71 and 2.83 mm) and 6 possible juveniles (1.0– 1.97 mm);

Stat. 151-7: ZMH-K-41905—immature male (3.2 mm), 16 adult females (3.20–3.30 mm) and 11 juveniles (1.66–2.23 mm);

Stat. 153-7: ZMH-K-41904—adult female (3.3 mm), 12 adult females (3.18–3.44 mm) and 42 juveniles (1.22– 2.90 mm);

R/V “Polarstern”, ANT XIX /3, PS 61, 2002:

Stat. 46-7: ZMH-K-45819 6 adult females and 4 juveniles; ZMH-K-45820 2 adult females and 2 juveniles.

Description of adult female. Carapace (Figs. 2, 3). Carapace is elongated in lateral view, with evenly rounded posterior margin. Length 3.11–3.44 mm. Greatest height at mid-length. Infold: about 30 setae forming irregular row just within and parallel to antero-dorsal margin above incisur; about 25 short setae between this row and row of 15 setae along dorsal margin of rostrum (Fig. 2 B–D); about 40 setae present below incisur and on antero-ventral infold (Figs. 2 E, F, 3 A); broad list of posterior infold with about 20 broad transparent setae (= hyaline spines) with pores at bases, and about 100 more setae; posterior infold between broad list and posterior end of valve with 5 processes and about 16 setae (Fig. 3 B–D).

First antenna (Figs. 4 C–E; 5 A, B). 1st joint with medial and lateral spines (Fig. 4 C, D); 2nd joint also with medial and lateral spines, 1 short disto-lateral seta and without dorsal seta (broken?); 3rd joint with 1 small bare ventral seta and 6 long dorsal setae (all with long spines) (Fig. 3 C, E); 4th joint with 2 short ventral and 1 long dorsal setae. Sensory seta of 5th joint with short proximal filament and 6 long terminal filaments. 6th joint with medial seta. 7th joint (Fig. 5 A, B): a-claw smooth, c-seta with 3 marginal and 2 terminal filaments. 8th joint (Fig. 5 A, B): d- and e-setae bare, d-seta somewhat shorter and more slender than e-seta; f-seta with 4 marginal and 2 terminal filaments; g-seta with 4–5 marginal and 1–2 terminal filaments.

Second antenna (Fig. 5 C–F). Protopodite with short slender medial seta (Fig. 5 D, E). Endopodite 3-jointed with terminal filament only slightly longer than stem (Fig. 5 D, F). Exopodite 9th joint with large terminal process (Fig. 5 C).

Mandible (Figs. 6 A–E; 7 A–D). Coxale endite (Fig. 7 A, B): ventral branch with spines forming 4 rows and tip with 2 small spines; ventral margin of dorsal branch with 6 pairs of teeth, small process set with setules and tip represented by 2 slender long spines. Basale endite (Figs. 6 A; 7 C, D) with 4 dentate terminal setae, glandular peg, 2 dwarf setae and 2 triaenid setae (Fig. 6 E, F). U-shaped margin depression and short triaenid seta present on basale proximal endite. Dorsal margin of basale with 4–6 middle setae (Fig. 6 A–C). Exopodite about one-third the length of 1st endopodite joint, with hirsute tip and 2 terminal setae (Fig. 6 A–C). Endopodite first joint with 3 long spinous ventral setae. Second joint (Fig. 6 A, D, E): dorsal margin with 2 midlength slender proximal setae with short spines, stout spinous a-, b-, c- and d-setae, 1 slender short seta between a- and b-setae, 1 slender long seta between b- and c-setae, 1 slender long seta between c- and d-setae and 8 cleaning setae (4 at base of b-seta and 4 at base of c-seta); ventral margin with 3 long spinous setae. Third joint with stout claw and 5 setae.

Maxilla (Fig. 7 E, F). Epipodial appendage large with long narrow tip (Fig. 7 E). Proximal and distal endites each with 3 long setae. Dorsal margin of basale with 1 proximal and 3–4 short setae, all bare; ventral margin with 7 short proximal and 1 long distal setae, all bare. Endopodite: suture between 1st and 2nd joints absent; 1st joint with 1 short alpha-seta and 1 long beta-seta; seta of end joint slightly longer than beta-seta on 1st joint.

Fifth limb (Fig. 7 G). Epipodial appendage with about 70 setae. Spinous exopodial seta reach distal end of comb. Comb with 4 setae near ventral margin.

Sixth limb (Figs. 6 F; 8 A). Anterior margin with upper and lower setae; antero-ventral corner and flap with total of 5–6 setae (Fig. 6 F); postero-ventral margin with 21–24 setae.

Seventh limb (Fig. 8 B). Each limb with 16–17 setae: 12–13 proximal (6+6 or 6+7) and 4 distal setae (2+2), each seta with 3–4 bells; opposing terminal combs each with 13 teeth with pointed tip.

Caudal furca (Fig. 8 C, D). Left lamella with 9 claws and right lamella with 10 claws (3 posterior ones on each lamella seta-like); claws 1–6 (7) with small teeth on posterior edge (Fig. 8 C).

Medial and lateral eyes (Fig. 4 C, D). Medial eye large, bare; lateral eye small with several ommatidia.

Rod-shaped organ (Fig. 4 A, B, D). 1-jointed, widening near middle and tapering to rounded tip.

Lips (Fig. 4 D, F): Upper lip consisting of hirsute left and right lobe on low central part, each lobe with one small process.

Description of immature male.

Carapace. Length 3.2 mm. Smaller rounded at posterior than female. Greatest height at the first third of the carapace.

Second antenna (Fig. 8 H). Endopodite: 3-jointed; 1st and 2nd joints bare; suture between 1st and 2nd joints indistinct; 3rd joint with proximal ventral seta with blunt tip.

Rod-shaped organ (Fig. 8 E, F). Two jointed, slightly tapered.

Upper lip (Fig. 8 F, G). Upper lip consisting of hirsute left and right lobe on low central part, left lobe with 2 small spines (of which 1 spine placed on process) and right lobe with 1 small process (Fig. 8 G).

Remarks. Our specimens are somewhat different from the specimen described by Kornicker 1975 (see Table 3).

number of transparent and common (in brackets) setae on list of 34–35 (160) 20 (100) posterior infold

Distribution. This species lives in the Weddell Sea and adjacent waters at a depth range of 132–2124 m (Kornicker 1975; Hartmann 1986, 1989, 1990; herein).