Parasterope sohni Kornicker & Caraion 1974

Parasterope sohni

HOLOTYPE.—[USNM 141556], ovigerous female, length 1.78 mm. Valves and some appendages in alcohol, remaining appendages on slide, in collection of Museum of Natural History “Grigore Antipa,” Bucharest Romania.

TYPE-LOCALITY.—Station X054.

ETYMOLOGY.—The species is named in honor of Dr. I. Gregory Sohn.

ADDITIONAL SPECIMENS.—USNM 141829, 1 A-l male, Station X043.

DISTRIBUTION.—Collected off Spanish Sahara and Mauritania at depths of 480–534 m (Figures 2, 3).

DESCRIPTION OF FEMALE (Figure 7).—Carapace elongate in lateral view, greatest height at valve middle (Figure 7a); dorsal and ventral margins evenly rounded and subparallel; incisur just below valve middle (Figure 7b); posterodorsal margin angular.

Infold (Figure 7c): Behind rostrum with about 6 bristles along list, about 10 bristles between list and incisur, and about 25 bristles anterior and dorsal to list; about 25 bristles on broad anteroventral infold; about 10 bristles along ventral infold to point opposite lowermost hyaline flaplike bristle on posterior list. List beginning near inner margin of anterior part of infold (Figure 7b), extending along ventral infold and meeting with slight overlap the posteroventral corner of broad posterior list; broad posterior list with about 21 broad transparent bristles, 2–4 long bristles on anterior part, and about 25 short bristles, 1 or 2 short bristles between each transparent bristle; about 8 short bristles and 5 faint processes between broad posterior list and posterior margin of valve; dorsal part of posterior infold with field of about 21 minute processes.

Selvage: Lamellar prolongation with marginal fringe along lower margin of incisur.

Size: [USNM 141556], holotype, length 1.78 mm, height 0.88 mm, height 49 percent of length.

First antenna (Figure 7d): 1st and 2nd joints with spines on lateral and medial surfaces; terminal margin of 1st joint with small process just dorsal to midline on medial side; 2nd joint with short spinous lateral bristle and long spinous dorsal bristle; 3rd joint with minute ventral bristle and 6 long spinous dorsal bristles; 3rd plus 4th joints wider than long, separated by distinct suture; 4th joint with concave distal margin and 3 bristles, 1 long spinous dorsal bristle and 2 slender spinous (very faint spines) ventral bristles (longer of these almost reaching middle of 6th joint, shorter bristles reaching just past middle of 5th joint); 4th joint with minute spines forming single row on lateral surface; sensory bristle of 5th joint long, with 6 terminal filaments; no spines on 5th joint; medial bristle of 6th joint with few marginal spines. Seventh joint: a-bristle shorter than bristle of 6th joint; b-bristle reaching past tip of sensory bristle of 5th joint, with 5 filaments including stem (proximal filament just reaching past proximal end of next filament); c-bristle reaching past sensory bristle, with 9 marginal filaments plus 1 near tip. Eighth joint: d-bristle minute; e-bristle bare and reaching tip of sensory bristle; f-bristle bent dorsally, with 3 marginal filaments, tip bifurcate; g-bristle slightly longer than c-bristle, with 5 marginal filaments, tip bifurcate.

Second antenna: Protopodite with short spines forming rows on dorsal part of medial surface, and small medial bristle. Endopodite 3-jointed but distal joint not marked by suture (marked only by break in sclerotization of vestment); terminal bristle about one and one-half length of stem. Exopodite: 1st joint with long hairs forming clusters along distal part of dorsal margin; 2nd to 8th joints with short faint spines forming row along distal margins; bristle of 2nd joint just reaching 9th joint, with fairly long spines along ventral margin and a few hairs proximally along dorsal margin; bristles of 3rd to 8th joints with natatory hairs; 9th joint with minute lateral spine with square tip consisting of 5 points, and 3 bristles (2 long with natatory hairs, 1 short and either bare or with minute faint marginal spines); minute basal spines present on joints 6 to 8.

Mandible (Figure 7f): Coxale endite: small slender bristle present near base of ventral branch; ventral branch with 5 or 6 oblique rows of rather short spines; tip of ventral branch with 3 minute teeth; 1 additional minute spine present on dorsal margin just proximal to tip; dorsal branch with 7 or 8 angular nodes along ventral margin and small main spine; margin between main spine and tip of dorsal branch with minute spines (tip of branch obscure on single endite examined; dorsal branch of right mandible absent, possibly remained in mouth of specimen); dorsal margin of branch dentate distally. Basale: endite with usual 4 pectinate end bristles, 2 short dwarf bristles, elongate glandular peg and 3 triaenid bristles with 6–9 pairs of marginal spines (excluding terminal pair); dorsal margin of basale with spinous midbristle, and 2 spinous terminal bristles (lateral of these slightly shorter than midbristle; medial bristle reaching past middle of end joint of endopodite; both bristles missing on left limb). Endopodite: 1st joint with 3 long spinous ventral bristles; ventral margin of 2nd joint with 3 spinous terminal bristles; dorsal margin with short stout spines forming row proximal to single proximal bristle, and stout spinous a-, b-, c-, and d-bristles; 1 long spinous lateral bristle present between b- and c-bristles, and c- and d-bristles; 1 short spinous bristle (slightly medially) present between a- and b-bristles; 2 medial spinous cleaning bristles between b- and c-bristles; 5 medial spinous cleaning bristles forming oblique row from point just proximal to b-bristle to point just proximal to base of c-bristle; 1 long spinous medial bristle (about three-fourth length of d-bristle) present just distal to base of d-bristle; medial surface with few short spines forming rows; end joint with dorsal claw and 5 bristles, 4 long, 1 short, all with spines. Exopodite hirsute distally, with 2 short bristles reaching distal margin of 1st endopodite joint.

Maxilla (Figure 7g): Epipodite appendage hirsute, with pointed tip reaching to about middle of dorsal margin of basale; endite I with 4 bristles, 3 long, 1 short; endite II with 3 long bristles. Basale with hairs on medial surface and dorsal margin; medial surface with 1 short proximal bristle near dorsal margin; lateral surface with 1 proximal bristle (longer than proximal bristle on medial surface); ventral margin with 1 proximal backward-pointing bristle and 1 short distal bristle (latter bristle with base on lateral surface) and long spinous terminal bristle; dorsal margin with short distal bristle. Endopodite: 1st joint with 1 short dorsal bristle and 1 long -bristle with faint marginal spines; end joint with long spinous terminal bristle extending just past end of -bristle.

Fifth limb (Figure 7h): Epipodial appendage with 58 bristles; 1 slender bare bristle ventral to base of stout spinous exopodial bristle; 4 additional bristles (2 pairs) near ventral margin of comb; 1 additional bristle almost on ventral edge of comb near proximal paired bristles.

Sixth limb (Figure 7i): Medial surface with minute bristle in anterodorsal corner; anterior margin with 1 upper bristle and 1 lower bristle; anteroventral corner with 3 spinous bristles; lateral flap without bristles; posteroventral margin with 6 or 7 bristles near middle; medial and lateral surfaces hirsute.

Seventh limb (Figure 7j): Proximal and distal groups each with 6 bristles (3 + 3); each bristle with 3 to 5 bells. Terminus with opposing combs, each with 12–14 spinous teeth.

Furca: Each lamella with 10 claws of which posterior 2 or 3 are small bristle-like; claws 1 to 7 with long and short teeth along posterior margins; some main claws with hairs along anterior margins.

Rod-shaped organ: Elongate, 1-jointed, with rounded tip (Figure 7e).

Eyes: Medial eye without pigment, bare (Figure 7e); lateral eye minute, consisting of reddish brown pigment spots without ommatidia (Figure 7k,l).

Posterior: Dorsum consisting of short spinous thumblike process (Figure 7n).

Upper lip: Consisting of 2 hirsute lobes and hirsute lateral flap on each side; 1 or 2 minute anterior spines present on each lobe and 1 longer slender spine on anterior of saddle between lobes (Figure 7m).

Genitalia: Oval sclerotized process on each side (Figure 7n). Brush organ not observed.

Eggs: [USNM 141556] with 4 eggs in marsupium.

DESCRIPTION A-1 MALE.—Carapace similar in shape to female; USNM 141829, length 1.65 mm, height 0.83, height 50 percent length.

First antenna: Sensory bristle of 5th joint with 1 short proximal and 6 long terminal filaments.

Second antenna: Endopodite 3-jointed: 1st joint bare; 2nd joint elongate with 2 short distal bristles; 3rd joint elongate with 1 proximal bristle, tip rounded.

Mandible: Similar to that of female in having 1 short and 1 long terminal bristle on dorsal margin of basale; dorsal margin of 2nd endopodite joint of endopodite with 2 proximal bristles.

Sixth limb: Middle of end joint with 4 or 5 short bristles, anteroventral corner of end joint with 3 short bristles; anterior margin of limb with upper and lower bristles.

Seventh limb: Each limb with 12 bristles, 6 proximal (3 + 3), 6 terminal (3 + 3).

Furca: Each lamella with 9 claws; posterior 2 small, bristle-like.

Rod-shaped organ: Similar to that on female.

Eyes: Lateral eye minute, similar to that of adult female. Medial eye similar to that of female.

Posterior: Thumblike spinous process similar to that of female.

Upper lip: Similar to that of female.