Skogsbergiella

Chavtur, Vladimir G. & Keyser, Dietmar, 2015, Benthic Ostracods of Skogsbergiella (Myodocopina: Cylindroleberididae) from the Southern Ocean, Zootaxa 4048 (4), pp. 508-522 : 516-521

Skogsbergiella species A

( Figs 7–10 )

Material. One adult female, ZMH K- 41907, length 3.24 mm, appendages are mounted on slide (ZMH-K 41907/1) and valves are preserved in alcohol (ZMH-K 41907/2), stored in the collection of the Zoological Museum in University of Hamburg, Germany.

Type locality. R/V “Polarstern, ANT VIII/5: adult female, Station: 16-423, 75°49.9´S – 27°31.7´W to 74°51.55´S – 27°40.3´W, depth 475 m, Agassiz trawl on 18 January 1990.

Description of adult female. Carapace ( Fig. 7 ): Elongate with evenly rounded posterior. Length 3.24 mm. Greatest height in middle (51%). Anterior and posterior infolds not well defined (Figs. B, C). List on posterior infold with 2 setae between hyaline setae ( Fig. 7 D).

First antenna ( Figs 8 D, E): 1st segment bare; 2nd segment with spines on ventral and dorsal surface, with 1 dorsal long spinous and 1 lateral short bare setae; 3rd segment with 6 spinous dorsal setae and 1 short recurved bare ventral seta; 4th segment with 1 long dorsal seta with short marginal spines and 1–2 short ventral setae; sensory of 5th segment with slender proximal filament, distal filaments broken; setae on 7th (excluding a-seta) and 8th segments broken.

Second antenna ( Figs 8 F–J): Protopodite with short slender medial seta ( Fig. 8 F, J). Endopodite 2-segmented: 1st segment bare; 2nd segment with long terminal seta. Exopodite: 9th segment with 2 terminal spines ( Fig. 8 H, G, I) and without spines on right limb.

Mandible ( Figs 9 , 10 A): Branch of coxale endite broken and lost. Basale: endite with 4 terminal spinous setae, distally with 4 tridentid setae with some marginal pairs of spines and 1 dwarf seta and proximally with glandular peg and 1 tridentid seta; 1 tridentid seta on basale near endite; dorsal margin of basale with 2 long terminal setae, 1 short subterminal seta and 6 middle setae. Exopodite about one-half length or somewhat shorter than dorsal margin of 1st endopodite segment and with 2 short bare subterminal setae. Endopodite: 1st segment with 3 long ventral setae and 2 dorsoterminal long spines; 2nd segment with 3 long terminal setae on ventral margin, dorsal margin with 1 short proximal seta and stout spinous a-, b-, c- and d-setae, 2–3 short setae between a- and b-setae, 2 fairly long setae between b- and c-setae, 1 long seta between c- and d-setae and 1 long seta near base of d-seta; 2 rows of 4–5 and 5 setae present medially between b- and d-setae; 3rd segment with 1 claw and 5 setae of which 3 are long setae.

Maxilla ( Fig. 10 B): Epipodial appendage triangular and hirsute. Proximal endite with 4 long setae; distal endite with 3 long setae. Basale dorsally spinous: dorsal margin with 1 proximal and 1 distal short setae; ventral margin with 1 short proximal and 1 long spinous terminal setae; lateral side with 1 short proximal seta. Endopodite: anterior margin with minute seta, posterior margin with 1 long spinous terminal seta; end segment with 1 long spinous terminal seta.

Fifth limb ( Fig. 10 C, E): Epipodial appendage deformed. Lateral side with long stout exopodite seta (extending slightly past end of comb, double seta near base of exopodite seta) and 6 near ventral margin.

Sixth limb ( Figs.10 D, F, G, H): Anterior margin only with 1 upper seta; anteroventral corner with 5 setae; lateral flap with 1 seta; posteroventral margin with 26 setae.

Seventh limb: Limb with 26–28 setae, 24–26 proximal (12+12 on left and 13+13 on right limbs) and 4 terminal (2+2); opposing terminal combs with 16 spinous teeth on each side.

Caudal furca. Each lamella with 9 claws, 1st–7th claws and 8th– 9th claw-like setae.

Eyes ( Figs 8 A, B, D). Lateral eye well developed and about 2/3 diameter of medial eye; anterior surface of medial eye hirsute.

Rod-shaped organ ( Fig. 8 C, D): 1-segmented, fairly elongate and thick with rounded tip.

Comparison. Skogsbergiella species A is closely related to S. skogsbergi Kornicker, 1971 but differs by lesser size of carapace, number of middle setae on dorsal margin of mandibular basale and teeth on combs of seventh limb ( Table 1 ). Also it is similar to S. senex Kornicker, 1996 (in: Kornicker & Poore, 1996) with following exceptions: lateral eyes present, dorsal margin of mandibular basale with 6–7 setae ( Table 1 ).

Remarks. Skogsbergiella species A is described in open nomenclature because the material is of poor quality, its carapace is covered with dirt and many setae on limbs are broken.

Characteristics

spinifera

skogsbergi scotti macrothrix locus pax senex tetratrix A species

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S S S S S S S S S Material. R.V. “Polarstern“, PS 61, ANT XIX/3, ANDEEP I cruise, Station 46-7-E: juvenile (1. 57 mm), taken with an epibenthic sledge trawled from 60°39.19´S, 53°56.85´W, depth 2889.2 m to 60°38.06´S, 53°57.51´W, depth 2892.8 m, on 30 January 2002. R.V. “Polarstern”, PS 67, ANT XXII/3, ANDEEP III cruise Station 133-2, juvenile (1. 78 mm), epibenthic sledge trawled from 62°46.49´S, 53°3.50´W, to 62°46.38´S – 53°3.98´W, depth 1580 m, 16 March 2005.

Figures

FIGURE 7. Skogsbergiella species A (Adult female—ZMH-K 41907). A, right valve of carapace in lateral view; B, rostrum infold; C, posterior infold of left valve; D, pores and flap-like setae along posterior list.

FIGURE 8. Skogsbergiella species A (Adult female—ZMH-K 41907). A and B, lateral eyes; C, rod-shaped organ; D, rodshaped organ, lateral and medial eyes, and first antenna (terminal setae on first antenna not shown); E, distal half of first antenna (distal and terminal setae not shown); F, second antenna (without 2 – 9 exopodite segments); G, exopodite of second antenna (without setae on 3 – 9 segments); H and I, distal part of exopodite on second antenna (with and without setae); J, detail of second antenna.

FIGURE 9. Skogsbergiella species A (Adult female—ZMH-K 41907). A, mandible (only main setae shown); B and D, dorsal margin of middle mandible; E and F, dorsal side of 2 nd endopodite segment of mandible; G, distal part of mandible; H, basale endite and proximal part of basale on mandible; I, detail of basale endite and basale segment on mandible; J, detail of basale endite on mandible.

FIGURE 10. Skogsbergiella species A (Adult female—ZMH-K 41907). A, dorsal margin of basale on mandible; B, maxilla; C and E, comb of fifth limb; D, F, and H, anterior of sixth limb; G, sixth limb.