Xandarasterope storthynx Kornicker ex Kornicker & Poore 1996

Xandarasterope storthynx Kornicker

Xandarasterope species A. Kornicker, 1994, fig. 111d-f.

ETYMOLOGY.—From the Greek storthynx (point, spike).

HOLOTYPE.—NMV J40026, partly dissected adult female in alcohol.

TYPE LOCALITY.—Slope 66, 38°40.29′S, 149°18.06′E, Victoria, 96 km S of Point Hicks; depth 2900 m.

PARATYPES.—Slope 17: USNM 193999, 1 ovigerous female on slide and in alcohol; NMV J40023, 1 juvenile in alcohol. Slope 66: USNM 193958, 1 ovigerous female on slide and in alcohol; NMV J40024, 1 late juvenile (length 2.02 mm, height 1.45 mm); NMV J40025, 1 early juvenile (length 1.64 mm, height 1.22 mm).

DISTRIBUTION.—Slope 17, 2250 m. Slope 66, 2900 m.

DESCRIPTION OF ADULT FEMALE (Figures 70–73).—Carapace oval in lateral view with incisur ventral to valve midheight; dorsal and ventral margins strongly convex (Figures 70a, 73a,c).

Infold: Rostral infold dorsal to list of right valve of USNM 193958 with about 10 long bristles, 30 short bristles, and about 10 empty sockets once containing bristles (Figure 70c); rostral infold with about 6 long bristle along list and about 25 long bristles between list and incisur (Figure 70c); anteroventral infold with about 90 bristles; narrow list with anterior end near inner end of incisur continues along ventral margin then broadens along posteroventral and posterior infolds (Figure 70d,e); ventral infold to point opposite ventral hyaline flap-like bristle on broad posteroventral list with about 60 bristles between list and valve edge; posteroventral and posterior infolds (from point opposite ventral flap-like bristle) with row of about 11 long bristles followed by about 40 shorter bristles (not all shown in Figure 70d,e); 7 short tubular processes between posterior list and valve edge in same region as row of small bristles (Figure 70d); broad posteroventral and posterior list with 28–31 broad hyaline flap-like bristles and 64 (USNM 193999) to 108 (USNM 193958) closely spaced slender bristles (about 16 long, remainder short; generally about 2–4 slender bristles between each pair of flap-like bristles) in row anterior to hyaline flap-like bristles (not all shown in Figure 70d,e); some flap-like bristles longer and broader than others and with about 10 tubular pores at base (not all shown in Figure 70d,e); on left valve only of USNM 193958 posterior part of ventral infold with small crescent-like structures (the 10 posterior of these shown in Figure 70e).

Selvage: Short fringed lamellar prolongation along inner part of ventral edge of incisur (Figure 70c). Short fringed segment also present on right valve just dorsal to dorsal end of broad posterior list.

Vestment: Vestment proximal to anterodorsal infold with long spines; a few spines on posterodorsal vestment just dorsal to broad posterior list.

Central Adductor Muscle Attachments (Figures 70b, 73c,d): Comprising 53–56 small ovoid attachments.

Carapace Size (length, height in mm): Slope 17: USNM 193999, 2.22, 1.68, height 76% of length. Slope 66: Holotype, 2.39, 1.99, height 83% of length; USNM 193958, 2.37, 1.85, height 78% of length. Length range 2.22–2.39, height range 1.68–1.99; range of height as percent of length 76–83.

First Antenna: 1st and 2nd joints spinous; 2nd joint with long spinous dorsal bristle and backward-pointing lateral bristle (Figure 70f). 3rd joint with distinct suture separating it from 4th joint, with row of distal spines on ventral margin extending onto lateral surface, 1 small bare ventral bristle, and 6 dorsal bristles (proximal 4 single with long spines; next 2 paired (lateral with long spines, medial with short spines)). 4th joint with ventral spines, 2 small ventral bristles (bare or with short spines), and 1 long dorsal bristle with short spines. Sensory bristle of 5th joint long slender, with short proximal filament and 6 long distal filaments. Medial bristle of 6th joint long, with short spines. 7th joint (Figure 70g): a-bristle claw-like with minute dorsal spines in proximal third; b-bristle about ; longer than a-bristle, with 4 marginal filaments; c-bristle about 2 times length of a-bristle, with 9 marginal filaments. 8th joint (Figures 70f,g, 73b): d- and e-bristles filament-like, slightly longer than f-bristle, bare with blunt tips; e-bristle stouter than d-bristle (distal part of d- and e-bristles broken off on USNM 193958 (Figure 70f), but on holotype d-bristle complete on left limb, and e-bristle complete on right limb (composite shown in Figure 73b)); f-bristle almost twice length of a-bristle, bent dorsally, with 5 marginal filaments; g-bristle about same length as c-bristle, with 8 marginal filaments.

Second Antenna (Figures 71a, 73e): Protopodite with abundant slender spines on dorsal and ventral margins and medial surface, and small bare distomedial bristle. Endopodite well developed, distinctly 3-jointed, with long terminal filament. Exopodite: 1st joint with few distal spines on concave margin (not shown); bristle of 2nd joint reaching end of 9th joint, with abundant fairly short hair-like spines; bristles of joints 3–8 with natatory hairs, some also with minute spines at about ; length; 9th joint with 3 bristles (2 long with natatory hairs, 1 short (dorsal) with few small hairs); joints 2–8 with row of small spines along distal edges but no basal spines; 9th joint with 1 or 2 small lateral spines.

Mandible: Coxale endite (Figure 71b): Dorsal branch with long slender bare bristle near base of ventral branch (dorsal branch broken off on both limbs of USNM 193958); ventral branch with 3 or 4 oblique rows of slender spines and tip with 3 small teeth (dorsal larger). Basale endite with small glandular peg, 2 dwarf bristles, 5 triaenid bristles with 14–19 pairs of spines excluding terminal pair, and 4 spinous end bristles (Figure 71c). Basale (Figure 71c): Ventral margin with 1 triaenid bristle (with 8–11 paired spines excluding terminal pair) close to base of endite and proximal to U-shaped boss, and several fairly stout spines distal to U-shaped boss; dorsal margin with spines and 2 long stout terminal bristles with short spines; medial and lateral surfaces with rows of spines. Exopodite reaching midlength of dorsal margin of 1st endopodial joint, hirsute with 2 short subterminal bristles (Figure 71c). 1st endopodial joint with 3 long ventral bristles (shortest with short spines, others with long spines). 2nd endopodial joint: Dorsal margin with 3 short slender proximal bristles (Figure 71c), stout spinous a-, b-, c-, and d-bristles (all about same width and length), long spinous lateral e-bristle between b- and c-bristles, long stout lateral f-bristle (about same length as d-bristle) between c- and d-bristles, and long stout spinous medial g-bristle just distal to base of d-bristle; medial surface with spines, and 16–18 spinous cleaning bristles near dorsal margin (not shown); ventral margin with 3 long spinous terminal bristles (Figure 71d). 3rd endopodial joint with straight dorsal claw with few minute ventral teeth at midlength and 1 short and 4 long spinous bristles (Figure 71d).

Maxilla (Figure 71e): Endite I with 1 short bristle and 3 long spinous bristles; endite II with 3 long spinous bristles and 1 minute bare bristle. Epipodite hirsute, with narrow tip reaching to about midlength of dorsal margin of basale. Basale: hirsute; dorsal margin with 2 bristles (1 proximal, 1 distal); ventral margin with 6 slender bristles on USNM 193999 and 9 or 10 on USNM 193958, and 1 long spinous terminal bristle; lateral side with short proximal bristle near midheight. 1st endopodial joint with ventral and dorsal hairs, short distal alpha-bristle, and long beta-bristle. 2nd endopodial joint with terminal bristle either shorter than beta-bristle or about same length.

Fifth Limb (Figure 72a): Comb with stout spinous exopodial bristle reaching past tip of comb, 2 slender bristles just ventral to base of stout bristle, 2 pairs of bristles closer to ventral edge of comb, long hairs (not all shown) on dorsal edge of tip, and abundant short slender hairs (with bases on medial side and medial to ventral bristles) along ventral edge; 4 bristles with bases on lateral side almost on ventral margin (1 proximal, 1 at midlength, 2 near tip).

Sixth Limb (Figure 72b): Small medial spine in proximal anterior corner. Anterior margin with a short bristle at upper and lower endite sutures; anteroventral corner with 2 short bristles on USNM 193999 and 4 short bristles on USNM 193958; lateral flap with 2 or 3 hirsute bristles (anteroventral corner plus lateral flap with total of 5–7 bristles); ventral and posterior margins with 23–29 bristles (posterior 7 or 8 plumose, others with long proximal and short distal hairs). Limb hirsute.

Seventh Limb (Figure 72c): Each limb with 17–22 bristles (holotype and USNM 193999 with 17 or 18 bristles; USNM 193958 with 22 bristles); 2 long proximal and 2 long terminal bristles with 4 or 5 bells, others with 2 or 3 bells. Terminus with opposing combs, each with 12–15 spinous teeth.

Furca (Figures 71f, 72d, 73f,g): Each lamella with 6 stout claws followed by 3 ringed bristle-like claws; 2 or 3 lateral bristles (similar to bristle-like claws) present almost on ventral margin (1 between claws 2 and 3, 1 between claws 3 and 4, and 1 or none between claws 4 and 5); right lamella anterior to left by width of base of claw 1.

Bellonci Organ (Figures 71g, 73h): Elongate, broadening and striated near midlength; sides subparallel or tapered distal to broad segment; tip broadly rounded.

Eyes: Lateral eyes absent. Medial eye unpigmented, with abundant dorsal hairs (Figures 71g, 73h).

Lips (Figures 72e, 73i): Upper lip with 2 hirsute lobes separated by saddle; anterior margin of saddle hirsute, undulate, with 1–3 short spines, and appearing more sclerotized than usual for members of subfamily; each lobe with stout anterior spine. Lower lip a hirsute flap on each side of mouth.

Genitalia (Figure 72g): An indistinct oval on each side of body anterior to furca.

Gills: 7 long gills on each side of body.

Anterior of Body: Without anterior process.

Posterior of Body (Figures 71f, 72f, 73g): Middle part hirsute; short thumb-like dorsal process with stiff spines.

Y-Sclerite (Figure 72f): Typical for subfamily.

Eggs: Slope 17: USNM 193999 with 9 well-developed eggs in marsupium (length of 1 egg 0.46 mm). Slope 66: USNM 193958 with 10 eggs in marsupium (length of 1 egg 0.55 mm). Location of 1 egg in each specimen shown in Figures 70a, 73c.

Parasites: Holotype with a juvenile nematode (identified as parasitic by Duane Hope, Smithsonian Institution). (The nematode was observed on a slide after the ostracode was partly dissected; whether it was originally inside the shell or inside the body of the ostracode is not known. The body and carapace of the holotype were examined later and no additional nematodes are present. The nematode is mounted in glycerine on a separate slide deposited with the holotype of X. storthynx in the Museum of Victoria.)