Parasterope cf. styx Kornicker, 1975

Chavtur, Vladimir G. & Keyser, Dietmar, 2016, Description of new members of the family Cylindroleberididae (Ostracoda: Cylindroleberidoidea) from the Southern Ocean, Zootaxa 4137 (3), pp. 301-329 : 313-319

Parasterope cf. styx Kornicker, 1975

( Figs. 9 A–D, 10–13)

1975 Parasterope styx , new species Kornicker: 432–436, figs. 270, 271.

Material ( Fig. 1 ). R/V “Polarstern”, ANT XIX /3, PS 61, 2002:

Stat. 42-2: ZMH-K-41909—immature male (length 2.10 mm).

Description of immature male. Carapace ( Fig. 9 ) oval in lateral view with greatest height near middle. Length 2.10 mm. Incisur well below middle of valve. Infold behind rostrum with 18 setae between list and outer margin; about 14 setae on rostral list; only 2 setae between list and incisur; infold below incisur with about 40 setae. Posterior infold between broad list and valve margin without setae.

First antenna ( Fig. 10 C, D). First joint with list of faint spines near ventral margin; 2nd joint with spines forming clusters on lateral surface, 1 long seta on dorsal margin with long proximal and short distal marginal spines, and 1 short distal bare lateral seta near dorsal margin; 3rd joint with 1 short seta on ventral margin and 6 long spinous setae on dorsal margin; 3rd plus 4th joint somewhat longer than wide; 4th joint with 1 long seta (with short marginal spines) near dorsal margin and 2 midlength bare setae on ventral margin; sensory seta of 5th joint with 6 filaments (4 proximal and 2 distal); seta of 6th limb slightly longer than a-claw of 7th limb. 7th joint ( Fig. 10 C): aclaw bare, b-seta with 3 proximal and 2 terminal filaments, c-seta broken. 8th joint ( Fig. 10 C): d-seta minute, e-seta bare, f-seta with 16 short proximal and 2 long terminal filaments, g-seta with 6 long proximal and 2 long terminal filaments.

Second antenna ( Fig. 10 E–H). Protopodite with short slender medial seta ( Fig. 10 f). Endopodite: 3-jointed; 1st and 2nd joints bare; 3rd joint with proximal ventral seta with blunt tip.

Mandible ( Figs. 11 A–D; 12 A–D, G). Ventral branch of coxale endite broken and lost. Basale endite with glandular peg, 4 terminal spinous setae, only 2 triaenid setae and 1 dwarf seta about three-fifth the length of triaenid seta ( Fig. 12 C, D). Basale: ventral margin with U-shaped sclerotized area and with minute thick spines, dorsal margin without midlength setae. Exopodite with hirsute tip and only 1 short subterminal seta not quite reaching end of 1st endopodite joint ( Fig. 12 A, B). Endopodite: 1st joint with 3 long spinous ventral setae; dorsal margin of 2nd joint with single spinous proximal seta about half length of a-seta, and spinous a- (or a1- and a2- setae on right limb, see Fig. 11 D), b-, c-, and d-setae, 1 short and 1 long seta between b- and c-setae, 1 seta below d-seta; medial surface with 2–3 cleaning setae between b- and c-setae.

Maxilla ( Fig. 12 F, E). Epipodial appendage slightly hirsute. Proximal and distal endites each with 3 long spinous setae. Basale: dorsal surface hirsute; medial surface with 1 proximal seta near base of epipodite; lateral seta absent (?); dorsal margin with 1 seta; ventral margin with 1 proximal and 1 distal seta; 1st endopodite joint with 1 short dorsal and 1 long ventral seta; 2nd joint with long terminal seta; suture between 1st and 2nd joints indistinct.

Fifth limb ( Fig. 13 A, B). Epipodial appendage with about 60 plumose setae. Comb with long setules and 3 short and 1 long bare setae near ventral margin. Exopodial stout plumose seta reaching past end of comb and with small swelling in middle.

Sixth limb ( Fig. 13 C, D). Antero-ventral corner with 2 short bare setae; anterior without seta at lower suture, but with 5 medial short bare setae, postero-ventral margin with 16 spinous setae.

Seventh limb ( Fig. 13 E). Limb with 12 setae, 9 in proximal group (4+5) and 3 in distal group (1+2); each seta with 3 bells; opposing combs of terminus each with 7 teeth with bifurcate tip.

Caudal furca ( Fig. 13 F, G). Left lamella with 5 claws and 3 posterior setae, and right lamella with 6 claws and 2 posterior setae; posterior margin of each lamella and adjacent margin of body with minute spines.

Medial and Lateral eyes ( Fig. 10 A, B). Medial eye large with brown central part. Lateral eyes absent.

Rod-shaped organ ( Fig. 10 A, B). 2-jointed; 1st joint very short, 2nd joint long and rounded tip. Upper lip ( Fig. 10 A). Lip consisting of two hirsute lobes each lobe with 2 spines; flap present on each side of mouth.

Remarks. Our specimen somewhat differs from specimen described by Kornicker 1975 (see Table 5).

Character Female (Kornicker immature male

1975) (herein) Carapace length (mm) 2.01 2.10 number setae in row above incisur 11 14 number setae between list and incisor 14 2 number transparent setae on infold behind rostrum 40–50 18 between list and outer margin

First antenna filaments on g-seta 6 8 Mandible number triaenid setae on basale endite 3 2

ventral setae on comb 5 4–6 Sixth limb seta on anterior margin 6–7 5 setae in antero-ventral corner 1 2 Distribution. The species was collected at the type-locality, on the crest of the west rise of the Peru-Chile Trench and the Scotia Sea at depth range 3670–4303 m.

Figures

FIGURE 1. Map of the area with stations where ostracods of the family Cylindroleberididae were found within this study.

FIGURE 9. Parasterope cf. styx (Immature male—ZMH-K- 41909: A – D) and Bathyleberis grossmani (Adult female—E). Alateral view of right valve, B—rostrum and anterior infold of left valve, C—list and posterior margin of right valve, D—central adductor muscle attachments, E—lateral view of left valve.

FIGURE 10. Parasterope cf. styx (Immature male—ZMH-K- 41909). A—medial eye and rod-shaped organ, B— 1 st antenna, medial eye, rod-shaped organ, anterior body and upper lip, C—distal part of 1 st antenna, D—terminal part of 1 st antenna, E— 2 nd antenna, F—short medial seta on protopodite of 2 nd antenna, G—distal part of exopodite on 2 nd antenna, H and I—endopodite of 2 nd antenna.

FIGURE 11. Parasterope cf. styx (Immature male—ZMH-K- 41909). A—mandible (only main setae shown), B—endopodite and exopodite of mandible, C and D—dorsal surface of 2 nd endopodite segment of mandible.

FIGURE 12. Parasterope cf. styx (Immature male—ZMH-K- 41909). A—exopodite and 1 st endopodite segment of mandible, B—exopodite mandible, C and D—basale endite of mandible, E and F maxilla, G—ventral surface of basale of mandible.

FIGURE 13. Parasterope cf. styx (Immature male—ZMH-K- 41909). A and B—comb and exopodial seta of 5 th limb, C— 6 th limb, D—ventral and antero-ventral margins of 6 th limb, E— 7 th limb, F— 6 th – 8 th pairs of furcal claws and posterior part of body, G—left caudal furca and posterior part of body.