Parasterope styx Kornicker 1975

“Parasterope styx, new species

Figures 270, 271

HOLOTYPE.—USNM 137259, gravid female, length 2.01 mm. Valves and some appendages in alcohol, remaining appendages on slides.

TYPE-LOCALITY.—Vema Cruise 17, station V-17-6.

ETYMOLOGY.—The specific name "styx" is derived from the Greek and Latin "Styx" [= a river in the nether world of mythology] in reference to the great depth from which the specimen was collected.

MATERIAL.—Holotype.

DIAGNOSIS OF ADULT FEMALE.—Carapace oval in lateral view with greatest height near middle; 1 bristle present on posterior infold between broad list and valve margin; carapace length about 2.01 mm.

Mandible: Dorsal margin of basale with 2 faint rows of short spines on proximal part and without midbristle.

Maxilla: Basale hirsute with 1 distal bristle on dorsal margin.

Sixth limb: Anterior margin without bristle at lower suture, but with 6 or 7 bristles above upper suture.

Seventh limb: With 12 or 13 bristles.

Lateral eyes: Absent.

DESCRIPTION OF FEMALE.—Carapace oval in lateral view with incisur well below valve middle.

Infold: Infold behind rostrum with 40 to 50 bristles between list and outer margin; about 11 bristles on rostral list; about 14 bristles between list and incisur; infold below incisur with about 40 bristles; about 25 to 35 bristles on infold along ventral margin; list present starting near inner margin of anterior part of infold below incisur, extending along ventral infold, and continuing on posterior infold where it broadens; posterior list with about 35 broad transparent bristles and about 20 small bristles, not more than 1 small bristle between adjacent transparent bristles; 1 bristle present between broad posterior list and posterior margin of valve near dorsal end of list.

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

Size: USNM 137259, length 2.01 mm, height 1.48 mm.

First antenna: Medial and lateral surfaces of 1st joint with spines forming clusters; 2nd joint with spines forming clusters on proximal part of dorsal margin, few faint spines on ventral margin, 1 long bristle on dorsal margin with long proximal and short distal marginal spines, and 1 short distal spinous lateral bristle near dorsal margin; ventral margin of 3rd joint with 1 short bare bristle; dorsal margin with 6 bristles in 5 groups of 1, 1, 1, 1, 2 bristles, medial bristle of distal pair with short marginal spines, others with long proximal and short distal spines; 3rd plus 4th joints longer than wide; medial proximal margin of 3rd joint concave, lateral margin linear; distal margin of 4th joint slightly concave, distinct; dorsal margin of 4th joint with 1 long bristle with long marginal spines; ventral margin with 2 spinous bristles (longer of these reaching past distal end of 6th joint, other reaching to middle of ventral margin of 6th joint); sensory bristle of 5th joint with 6 filaments (proximal filament more slender than others); lateral surface of both 2nd and 5th joints with spines forming short row parallel to distal edge and near dorsal margin; medial bristle of 6th joint spinous, almost reaching end of sensory bristle of 5th joint. Seventh joint: a-claw with short spines along middle of dorsal margin; b-bristle broken but with S spinous marginal filaments on remaining part; c-bristle with 6 filaments including tip. Eighth joint: d-bristle absent or minute; e-bristle bare, almost reaching tip of sensory bristle; f-bristle bent at right angle to stem, broken on specimen, but with 2 marginal filaments on remaining part; g-bristle with 6 filaments including tip, some with marginal spines.

Second antenna: Protopodite with small medial bristle and spines along dorsal margin and dorsal part of medial surface. Endopodite 3-jointed; suture separating 2nd and 3rd joints indistinct on right limb of holotype, fairly distinct on left limb; terminal filament of 3rd joint about 4 times length of stem. Exopodite: 1st joint with cluster of long distal hairs on inner margin; bristle of 2nd joint reaching past 9th joint and with numerous narrow spines along ventral margin and fewer spines along dorsal margin; bristles of joints 3 to 8 with natatory hairs; 9th joint of right limb with 4 bristles, 2 long with natatory hairs, 2 short bare or with short marginal spines; 9th joint of left limb of holotype with 2 long bristles with natatory hairs and 1 short bristle with short marginal spines; joints 3 to 8 with short basal spines, joint 9 with short lateral spine; comb of short spines present along distal margins of joints 2 to 8.

Mandible: Ventral branch of coxale endite with 4 oblique rows of spines, and 2 slender spines and few hairs at tip; ventral margin of dorsal branch with about 6 pairs of weakly developed teeth and small main spine; dorsal bristle with short marginal hairs; small bristle present at basis of endite. Basale endite with glandular peg, 4 terminal bristles, 3 triaenid bristles with 6 to 8 pairs of marginal spines excluding terminal pair, and 1 dwarf bristle about two-thirds length of triaenid bristle. Basale: ventral margin with U-shaped sclerotized area: dorsal margin with 2 faint rows of short spines on proximal part and 2 long spinous terminal bristles. Exopodite with hirsute tip and 2 short terminal bristles not quite reaching end of 1st endopodite joint. Endopodite: 1st joint with 3 long spinous ventral bristles; dorsal margin of 2nd joint with single spinous proximal bristle about half length of a-bristle, and spinous a-, b-, c-, and d-bristles; medial surface spinous with 1 or 2 short bristles between b- and c-bristles, 3 to 5 spinous cleaning bristles forming oblique row between c- and d-bristles, 1 long spinous bristle distal to base of d-bristle; lateral surface with 1 long spinous bristle between b- and c-bristles and between c- and d-bristles; ventral margin of 2nd joint with 3 long spinous terminal bristles; end joint with long dorsal claw with minute teeth along middle of inner margin and 5 long spinous bristles.

Maxilla: Epipodite elongate hirsute; proximal endite with 4 spinous bristles, 3 long, 1 short; distal endite with 3 spinous bristles, middle bristle shorter than others. Basale hirsute; medial surface with 1 proximal bristle near base of epipodite; dorsal margin with 1 distal bristle; lateral surface with 1 short proximal bristle; ventral margin with 1 long proximal bristle, 1 short distal bristle and 1 long spinous terminal bristle. Endopodite: 1st joint with clusters of spines, short anterior bristle and long spinous 6-bristle; end joint with long spinous terminal bristle.

Fifth limb: Epipodial appendage with 72 bristles. Dorsal margin of comb bare except for hairs present at distal end. Exopodite: stout plumose bristle reaching past end of comb; 1 slender bristle near basis of main bristle; 5 bristles near ventral margin.

Sixth limb: Anteroventral corner with 1 minute medial bristle; anterior margin without bristle at lower suture, but with 6 or 7 medial bristles above upper suture; anteroventral corner with 1 or 2 bristles; posteroventral margin with 15 or 16 bristles; medial and lateral surfaces and margins of limb hirsute.

Sixth limb: One limb with 12 bristles, 6 in proximal group (2 + 4) and 6 in distal group (3 + 3); other limb with 13 bristles, 8 in proximal group (4 + 4) and 5 in distal group (2 + 3); each bristle with 2 to 4 bells; opposing combs of terminus each with 7 or 8 teeth; teeth bifurcate consisting of spinous outer part and smooth tipped inner part.

Furca: Each lamella with 9 claws including 3 posterior secondary bristlelike annulate claws. Primary claws with long and short teeth along posterior margins, some also with thin hairs along anterior margins.

Posterior: Posterior forming right angle, spinous.

Rod-shaped organ and eyes: Rod-shaped organ 1-jointed with rounded tip. Medial eye hirsute with reddish brown central part in preserved specimen. Lateral eyes not present.

Upper lip: Lip consisting of two hirsute lobes with linear ventral margin, each lobe with 2 spines; segment between lobes with 1 anterior spine; hirsute flap present on each side of mouth.

Eggs: USNM 137259 with 9 well-developed eggs and larvae.

COMPARISONS.—The new species differs from previously described Parasterope in having more than 2 anterior bristles on the 6th limb. The absence of lateral eyes is uncommon in the genus. The dwarf bristle on the basale endite of the mandible of P. styx is unusually long.

DISTRIBUTION.—This species was collected only at the type-locality, on the crest of the west rise of the Peru-Chile Trench, at a depth of 4303 m.”

(Kornicker, 1975B, p.432-436)

Parasterope styx Kornicker, 1975

Parasterope styx Kornicker. 1975a:432, figs. 270, 271.

Parasterope species A.—Kornicker, 1985:410–412 [part, only specimens from sample DS-60].

Parasterope species B.—Kornicker, 1985:410–412 [part, excluding specimen from sample DS-55 referred to Synasterope hirpex, herein].

HOLOTYPE.—Ovigerous female, length 2.01 mm, USNM 137259.

TYPE LOCALITY.—Vema Cruise 17, 37°57′S, 75°08′W, South Pacific, west of Chile, 4303 m, sta V-17–6.

MATERIAL.—BIOGAS III, R.V. Jean Charcot, sta 2: sample DS-41:1 adult female (USNM 158585) + 1 adult male (USNM 193255). BIOGAS IV, R.V. Jean Charcot, sta 1: sample DS-60: 1 instar I + 1 adult female (USNM 193254). BIOGAS V, sta 2: sample DS-66: 1 A–1 female. BIOGAS VI, R.V. Jean Charcot, sta 2: sample DS-75: 1 A–1 female.

DISTRIBUTION.—West of Bay of Biscay and west of Chile, 3250–4303 m.

SUPPLEMENTARY DESCRIPTION OF ADULT FEMALE (Figures 51, 52).—Carapace oval in lateral view with incisur below valve middle (Figure 51a, f).

Infold (Figure 51f, g): Infold behind rostrum with about 33 bristles between list and outer margin, about 6 on rostral list, and about 10 bristles between list and incisur; single bristle on list near inner end of incisur. Broad list ventral to incisur with about 30 bristles. Infold along ventral margin with about 23 bristles. List present starting near inner margin of anterior part of infold below incisur, extending along ventral infold, and continuing on posterior infold where it broadens; broad posterior list with about 30 transparent flap-like bristles and about 25 small bristles (generally 1 small bristle between adjacent flap-like bristles, but a few small bristles forming pairs between adjacent flap-like bristles). A single bristle between posterior end of list and posterior margin of valve observed only on right valve. A small indistinct process present between broad posterior list and edge of left valve near dorsal end; process absent on right valve.

Vestment (Figure 51g): Slender spines forming rows present on vestment lining anterodorsal, posterior and posterodorsal parts of valves proximal to inner margin of infold.

Size: USNM 193254, length 1.86 mm, height 1.34 mm; USNM 158585, length 2.00 mm, height 1.42 mm.

First Antenna (Figure 51e, h, i): 1st joint with medial and lateral hairs and spines. 2nd joint with medial, lateral, dorsal and ventral spines and 2 bristles (1 dorsal with stout marginal spines, 1 lateral with short marginal spines). 3rd joint with well-defined distal margin, minute spines on ventral margin and forming short row on lateral surface, short bristle on ventral margin, and 6 spinous dorsal bristles in 5 groups of 1, 1, 1, 1, and 2 bristles (medial bristle of distal pair with short marginal spines, others with long proximal spines). 3rd plus 4th joints longer than wide; 4th joint with slightly concave distal margins, short medial spines forming rows near dorsal margin, and 3 bristles with short marginal spines (1 ventral, 2 dorsal). 5th joint with stiff distal spines on dorsal margin and smaller spines at midlength; minute lateral spines forming rows near dorsal margin at midlength and terminal; sensory bristle with 6 terminal filaments (proximal 2 slightly more slender than others; tips of filaments and stem not shown on illustrated limb). 6th joint with stout medial bristle with short marginal spines. 7th joint: a-bristle claw-like, (tip broken off on both limbs of specimen examined, marginal spines absent from stumps); b-bristle with 3 distal filaments (with marginal hairs) excluding stem; c-bristle with tip broken of on illustrated limb, 6 filaments on remaining part. 8th joint: d-bristle minute, represented by peg with rounded tip; e-bristle broken off on illustrated limb, bare, well developed; f-bristle bent dorsally, tip missing on illustrated limb but with 4 marginal filaments on remaining part (distal of these with short marginal hairs); g-bristle with tip broken off on illustrated limb, with 4 filaments on remaining part.

Second Antenna (Figure 51j): Protopodite with small distal medial bristle and spines forming rows along dorsal margin and dorsal part of medial surface. Endopodite 3-jointed, with well-defined sutures separating joints; terminal filament about 3 times length of stem. Exopodite: 1st joint with long hairs forming rows along distal inner margin; bristle of 2nd joint reaching past 9th joint and with numerous spines along ventral margin; bristles of joints 3–8 with natatory hairs, some with few indistinct ventral spines near midlength; 9th joint with 4 bristles (2 long with natatory hairs, 2 short with short marginal spines); joints 3–8 with short basal spines and minute spines forming short row along distal dorsal edge; 9th joint with short pointed lateral spine about length of joint.

Mandible (Figure 51k): Coxale endite broken off both limbs of specimen examined. Basale endite with glandular peg, 4 end bristles, 3 triaenid bristles with 5–7 pairs of marginal spines excluding terminal pair, and 1 dwarf bristle about length of triaenid bristle. Basale: ventral margin with U-shaped sclerotized area, and short stout spines forming row (bases of most spines on lateral side); dorsal margin with 2 long spinous terminal bristles; medial surface with slender spines forming rows at midheight of joint. Exopodite with hirsute tip and 2 terminal bristles reaching proximal end of 1st endopodial joint. 1st endopodial joint with 3 long spinous ventral bristles. 2nd endopodial joint: ventral margin with 3 long spinous terminal bristles; dorsal margin with short proximal bristle about length of a-bristle, and stout spinous a-, b-, c-, and d-bristles; medial surface with spines forming rows, 1 cleaning bristles just distal to base of b-bristle, 4 cleaning bristles forming oblique row near base of c-bristle, and 1 long bristle (with short marginal spines) just distal to base of d-bristle; lateral surface with 1 long bristle (with short marginal spines) between b- and c-bristles, and 1 long bristle (with short marginal spines) between c- and d-bristles. End joint with long dorsal claw with slender spines along middle of inner margin, and 5 spinous bristles. (Not all marginal spines shown on illustrated bristles.)

Maxilla (Figure 52a): Epipodite elongate, hirsute with tapering tip. Endite I with 1 short and 3 long bristles; endite II with 3 long bristles. Basale hirsute; medial surface with 1 proximal bristles near midheight and 1 distal bristle near dorsal margin; ventral margin with fairly long proximal bristle and long, stout, spinous, terminal bristle; proximal lateral bristle not observed (possible obscured). 1st endopodial joint with long hairs forming row, 1 short anterior bristle, and 1 long spinous terminal bristle; 2nd joint with long spinous terminal bristle. (Not all marginal spines shown on illustrated bristles).

Fifth Limb (Figure 52b): Epipodite with about 70 bristles. Stout plumose exopodial bristle reaching past distal end of comb; 1 slender bristle just ventral to base of stout bristle and 5 bristles near ventral margin of comb (distal of these more slender than others).

Sixth Limb (Figure 51l): Trunk: anterodorsal corner with small ringed medial bristle; anterior margin without bristle at lower suture and 5 or 6 medial bristles dorsal to upper suture. Skirt: anteroventral corner with 1 or 2 slender bristles; posteroventral margin with 17 bristles; lateral flap with anterior hairs but no bristles. Medial and lateral surfaces and margins of limb hirsute.

Seventh Limb (Figure 52c): One limb with 13 bristles, 7 in proximal group (3 + 4) and 6 in distal group (3 + 3); other limb with 6 bristles in proximal group (3 + 3) and distal bristles unknown (broken off); each bristle with 2–4 bells. Terminus with opposing combs, each with 8 or 9 teeth (each tooth comprising spinous outer part and smooth tipped inner part).

Furca (Figure 52d): Each lamella with 9 claws including 3 ringed bristle-like claws; primary claws with long and short teeth along posterior margins and some with thin hairs along anterior margins; claw 1 of right lamella anterior to claw 1 of left lamella.

Bellonci Organ (Figure 51b, m): Elongate broadening near middle, with rounded tip.

Eyes (Figure 51b, m): Medial eye with nucleus of dark brown pigment when viewed in transmitted light and with marginal hairs. Lateral eyes absent.

Upper Lip (Figures 51c, d, n, 52e): Comprising 2 hirsute lobes (each with 6 spines) separated by saddle with 2 or 3 spines (Figure 52e). In lateral view all spines may not be visible (Figure 52c). Hirsute lateral flap present on each side of mouth (Figures 51c, n, 52e).

Posterior of Body (Figure 52d): Margin just dorsal to furca with minute spines; segment dorsal to midheight of posterior with long hairs along ventral and slender spines on dorsal posterodorsal corner broadly rounded and bearing spines forming short rows. Gill-like structures narrow, poorly defined except at distal ends.

Y-Sclerite (Figure 52d): Typical for subfamily.

Parasites: USNM 193254 + 2 A-1 females from DS-66, –75 with cyproniscid isopod (either juvenile or adult male) within carapace.

DESCRIPTION OF ADULT MALE (Figures 53, 54).—Carapace more elongate than that of female and with more open incisur, hairs forming vertical row near posterior end (Figure 53a).

Infold: Not examined.

Size: USNM 193255, length 2.44 mm, height 1.64 mm. First Antenna (Figure 53b): 1st joint with medial and lateral hairs and spines; 2nd joint with medial, lateral, ventral, and dorsal spines and hairs and 2 bristles (1 dorsal with stout marginal spines proximally and more slender hairs distally, 1 lateral with long proximal and short distal hairs). Suture between 2nd and 3rd joints and 3rd and 4th joints oblique; trapezoidal 3rd joint with small bristle on short ventral margin, and on long dorsal margin 6 spinous bristles in 5 groups of 1, 1, 1, 1, and 2 bristles (all bristles with long proximal and short distal spines). 4th joint trapezoidal with 1 stout bristle (with short marginal spines) on short dorsal margin and 2 slender bristles (with short marginal spines) on long ventral margin. 5th joint short, without spines (spines present on female 5th joint); sensory bristle stout with abundant filaments. 6th joint with numerous muscles forming bundle narrowing distally; medial bristle with base near dorsal margin (bristle about same length as combined joints 5–8, and with short marginal spines). 7th joint: a-bristle claw-like, broken on both limbs of specimen examined; b-bristle about twice length of bristle of 6th joint, with about 5 marginal filaments and long slender bare tip; c-bristle very long, with short section of tip missing on specimen examined, and with 33 short filaments on remaining part 8th joint: d-bristle absent; e-bristle about length of b-bristle, bare with blunt tip; f-bristle similar to c-bristle; g-bristle about twice length of b-bristle, with about 10 filaments.

Second Antenna (Figure 53c): Protopodite with small distal medial bristle. Endopodite 3-jointed: 1st joint bare, about length of 2nd joint; 2nd joint with 2 bristles distal to midlength; 3rd joint with long proximal filament, 6 rounded processes on margin just distal to filament, and pointed tip with 3 or 4 ridges along inner edge. Exopodite: elongate 1st joint with short spines forming rows along ventral margin and longer spines near distal end; 2nd joint about same length as combined joints 3–5; bristles of joints 2–8 long, with natatory hairs; 9th joint with 3 long bristles with natatory hairs (a 4th bristle probably broken off on limb examined); joints 2–8 with fairly long spines forming row along distal margin; 9th joint with short lateral spine with spines along flat distal end.

Mandible (Figure 54a): Coxale endite broken off both limbs of specimen examined. Basale: endite similar to that of adult female; dorsal margin with fairly long bare midbristle and 2 stout spinous terminal bristles; medial surface with small spines forming rows near midheight; ventral margin and lateral surface without short stout spines present on adult female. Exopodite similar to that of adult female. 1st endopodial joint longer than that of female but with similar bristles. 2nd endopodial joint: ventral margin with 3 long spinous terminal bristles; dorsal margin with 2 proximal bristles (proximal of these about length, and distal about length of a-bristle), stout a-, b-, c-, and d-bristles (all with marginal spines); medial surface with 1 or 2 cleaning bristles between b- and c-bristles but closer to b-bristle, 5 cleaning bristles forming oblique row near base of c-bristle, and 1 long bristle (with short marginal spines) just distal to base of d-bristle, and spines forming rows; lateral surface with long bristle (with short marginal spines) between b- and c-bristles (broken off on illustrated right limb but present on left limb), and 1 long bristle (with short marginal spines between c- and d-bristles. End joint similar to that of female.

Maxilla (Figure 53d, e): Similar to that of adult female except marginal spines not observed on teminal bristle of 2nd endopodial joint.

Fifth Limb (Figure 53f): Similar to that of adult female.

Sixth Limb (Figure 54b): Trunk: anterodorsal corner with small ringed bristle with slender tip; anterior margin without bristle at lower suture and 5 medial bristles dorsal to upper suture. Skirt: anteroventral corner with 1 slender bristle; posteroventral margin with 14 hirsute bristles; lateral flap with anterior hairs but no bristles. Medial and lateral surfaces and margins hirsute.

Seventh Limb (Figure 54c): Single limb examined with 12 bristles, 6 in proximal group (3 on each side) and same number and distribution in distal group; each bristle with up to 4 bells. Terminus with opposing combs, each with 7 or 8 teeth similar to those of female.

Furca (Figure 53g): Each lamella with 8 claws including 2 ringed bristle-like claws which follow the 6 primary claws; claw 1 of examined specimen with very sparsely distributed teeth along posterior margin; claws 2–6 with numerous long and short teeth along posterior margins and hairs along anterior margins; bristle-like claws with few marginal spines; claw 1 of right lamella anterior to claw 1 of left lamella.

Bellonci Organ (Figure 54d): Similar to that female.

Eyes (Figure 54d): Medial eye with light brown pigment when viewed in transmitted light and with indistinct marginal hairs. Lateral eyes absent.

Upper Lip (Figure 54e): Left and right lobes each with 3 or 4 anterior spines; middle saddle with 1 stout and 2 minute anterior spines.

Posterior of Body (Figure 53g), Y-Sclerite: In general, similar to that of adult female.

Genitalia (Figure 53g): Lobate with few bristles.

Parasites: USNM 193255 with cyproniscid isopod (either juvenile or adult male) within carapace.