Bathyleberis toxotes Kornicker 1986

Bathyleberis toxotes

ETYMOLOGY.—The specific name is from the Greek toxotes (“archer, bowman”) and is named for Thomas E. Bowman.

HOLOTYPE.—USNM 158232, adult female on slides and in alcohol.

TYPE-LOCALITY.—Gulf of Mexico, off Galveston, Texas, R/V Gyre, cruise 11, sta 8.

PARATYPES.—R/V Gyre, cruise 10, sta 16, USNM 158498, 1 juvenile male. R/V Gyre, cruise 11: USNM 158233A, 158233B, 1 adult female and 1 juvenile male, respectively, from same sample as holotype; USNM 158497, 1 juvenile female (molting), sta 2; USNM 158495, 1 adult female, sta 7; USNM 158496, 1 juvenile male, sta 12.

DISTRIBUTION.—Continental shelf off Texas at depths of 50–58 m.

DESCRIPTION OF ADULT FEMALE (Figures 26, 27).—Carapace extremely elongate with incisur at midlength of anterior margin; dorsal and ventral margins linear, parallel; anterior and posterior margins almost evenly rounded (Figure 26a,b,d).

Infold: Infold behind rostrum with about 25 bristles forming row near and parallel to anterior margin of rostrum (Figure 26e); about 10 smaller additional bristles along anterior end of dorsal margin; about 9 bristles forming row parallel to and just above dorsal margin of incisur; about 15 additional bristles in vicinity of rostral list; numerous minute bristles present on rostral infold posterior to the row of bristles just within anterior margin of rostrum; about 4 small bristles present at inner end of ventral margin of incisur; about 36 bristles on broad anteroventral infold in area extending from incisur to point where bristles form single row along ventral margin; ventral margin with about 30 bristles forming single row ending posteriorly at point where list becomes broad. List beginning at inner margin of anterior part of infold near incisur, extending along ventral margin, and continuing on posteroventral and posterior infold where it broadens; broad posteroventral and posterior list with about 17 broad transparent flap-like bristles and about 27 small bristles (1 or 2 small bristles between each pair of flap-like bristles); posteroventral infold with about 16 bristles between broad list and valve edge (posterior 3 or 4 of these bristles unusually long); posterior infold with 4 or 5 processes between list and valve margin (Figure 26f). Selvage ventral to incisur bearing broad lamella prolongation.

Selvage: Broad lamella prolongation with marginal fringe present along ventral margin of incisur; fringed lamella prolongation also present along posterodorsal margin; serrated selvage observed along posterior edge of valve (not shown in illustrated valve).

Size: USNM 158232, length 1.78 mm, height 0.93 mm, height 52.2 percent of length; USNM 158495, 1.71 mm, height 0.74 mm, height 43.3 percent of length; USNM 158233A, length 1.73 mm, height 0.75 mm, height 43.4 percent of length.

First Antenna (Figure 26g): 1st joint with lateral spines. 2nd joint with ventral and lateral spines and 1 spinous dorsal bristle. 3rd joint with poorly defined suture separating it from 4th joint; 3rd joint with small ventral bristle and 6 dorsal bristles (proximal 5 of these with long marginal spines; distal bristle with short marginal spines); 4th joint with 1 dorsal bristle with short marginal spines, 2 ventral bristles, and spines forming rows on lateral surface and ventral margin. 5th and 6th joints separated by diagonal suture; 5th joint with lateral spines forming distal row near dorsal margin; sensory bristle short, stout, with small proximal filament, and 6 long terminal filaments; 6th joint with few lateral spines forming rows, and 1 stout medial bristle. 7th joint: a-claw bare, recurved, about same length as combined lengths of 5th and 6th joints; b-bristle stout, almost twice length of a-claw, with 4 marginal filaments (the distal of these with marginal spines); c-bristle almost twice length of b-bristle, with 8 short marginal filaments. 8th joint: d- and e-bristles on small pedestal bearing lateral pore; d-bristle shorter than b-bristle, slender, unringed, with pointed tip and faint marginal spines; e-bristle stouter and longer than d-bristle, with distinct proximal rings and faint more closely spaced distal rings, tip blunt; f-bristle bent dorsally, with 5 marginal filaments, some with spines; g-bristle same length as c-bristle, with 5 marginal filaments.

Second Antenna (Figure 26h): Protopodite with medial and dorsal spines, and minute, distal, medial bristle. Endopodite with only 1 distinct suture near middle; long terminal bristle with blunt tip. Exopodite: bristle of 2nd joint reaching distal end of 9th joint, with few proximal ventral spines followed by slender, spine-like hairs along both margins; long bristles of joints 3–8 with few proximal spines and distal natatory hairs; 9th joint with 3 bristles (1 long, 1 medium, both with natatory hairs, 1 short, with small marginal hairs); joints 4–8 with small triangular basal spines; 9th joint with stout lateral spine about twice length of spine of 8th joint, and about length of 9th joint; joints 2–8 with slender spines forming row along distal margin (spines along medial side of 3rd joint much longer than others).

Mandible: Coxale endite (Figure 26j): minute medial bristle near base of ventral branch; ventral branch with spines forming 4 groups and tip with 3 minute teeth (ventral of these larger than others); ventral margin of dorsal branch with 4 teeth (some paired) followed by small recurved tooth and then main spine; margin of branch between main spine and tip appearing smooth and bearing 3 or 4 distal hairs; tip extended with fairly long marginal hairs; dorsal bristle hirsute (broken off on illustrated limb); dorsal margin of dorsal branch with few distal serrations. Basale endite with 3 pectinate terminal bristles, 3 triaenid bristles (with 3 pairs of teeth in addition to terminal pair), 2 minute dwarf bristles, and glandular peg (Figure 26i). Basale: ventral margin with 1 small medial bristle proximal to U-shaped depression; dorsal margin with 3 spinous bristles (1 at midlength, 2 terminal); lateral surface with spines forming rows (more abundant near dorsal margin). Exopodite minute, hirsute, with 2 small terminal bristles (Figure 26k). 1st endopodial joint with 3 stout, spinous, ventral bristles. 2nd endopodial joint: ventral margin with 3 stout terminal bristles; dorsal margin with 3 small proximal spines (2 of these with bases on medial surface; see detail on Figure 26i), 2 small proximal bristles, and stout, spinous, a-, b-, c-, and d-bristles; lateral surface with long bristle between c- and d-bristles; medial side near mid length of dorsal margin with 1 short cleaning bristle between a- and b-bristles, 1 cleaning bristle between b- and c-bristles, 6 cleaning bristles forming oblique row near base of c-bristle, and 1 long spinous bristle just distal to base of d-bristle; medial surface also with spines forming few rows near ventral margin. 3rd endopodial joint with short, straight, terminal claw, and 5 spinous bristles.

Maxilla (Figure 27a): Epipodial appendage hirsute distally; tip not reaching midbristle located near dorsal margin of basale. Endite I with 4 bristles (3 long, 1 short); endite II with 3 long bristles. Basale: medial surface and dorsal margin hirsute; medial side with 1 proximal bristle, and 1 midbristle near dorsal margin; ventral margin with 1 proximal bristle, 1 minute distal bristle, and 1 long, spinous, terminal bristle; lateral side with 1 short proximal bristle. 1st endopodial joint hirsute, with 1 short anterior bristle, and 1 long beta-bristle. 2nd endopodial joint with terminal bristle extending past beta-bristle.

Fifth Limb: Comb (Figure 27b): dorsal margin with long distal hairs; lateral side with long, spinous, exopodial bristle, 2 small slender bristles near base of long bristle, 2 pairs of small bristles near middle of ventral margin, 1 longer bristle proximal to paired bristles and closer to ventral margin, and 2 distal bristles with bases very close to ventral margin; ventral margin with 28 bristles forming single row (bristles with marginal hairs that flair near tip of bristle; distal bristle longer than others).

Sixth Limb (Figure 27c): Anterior margin with well-defined endite sutures, each bearing 1 spinous bristle; anterior tip of skirt with 6 spinous bristles; lateral flap with long hairs but no bristles; middle part of ventral margin of skirt with 12 or 13 spinous bristles separated by narrow space from 6 longer hirsute bristles. No medial spine observed near proximal anterior corner of limb.

Seventh Limb (Figure 27d): Each limb with 6 proximal bristles (3 on each side) and 6 distal bristles (3 on each side); each bristle with up to 5 bells; terminus consisting of opposing combs, each with about 12 spinous teeth.

Furca (Figure 26l): Each lamella with 10 claws, posterior of these bent dorsally; main claws with teeth along posterior margins (some teeth longer than others), and hairs along anterior margins.

Bellonci Organ (Figure 26m): Elongate with rounded tip.

Eyes (Figure 26m): Medial eye unpigmented, with few dorsal hairs. Lateral eye smaller than medial eye, unpigmented, with 6 divided ommatidia.

Upper Lip (Figure 26m): Consisting of 2 hirsute lobes, each with minute anterior spines some distance from ventral edge of lobe; a spinous hirsute flap present on each side of mouth posterior to lobes.

Genitalia (Figure 26l): Oval organ on each side of body anterior to furca (dotted on illustration).

Posterior of Body (Figures 26c): Posterodorsal corner rounded, hirsute.

Y-Sclerite (Figures 26c,l): Dorsal branch well developed; ventral branch longer than usual for subfamily, oriented posteroventrally.

COMPARISONS.—The only previously described species of Bathyleberis having a minute mandibular exopodite similar to that of the new species B. toxotes is B. california Baker, 1979:287. A supplementary description of the latter species based on a female paratype from California is presented herein. The major difference in the morphology of B. californica and B. toxotes is size. The length of the female B. californica is given by Baker (1979:293) as 2.66–2.69 mm, whereas the range of length of the female B. toxotes based on 3 specimens is 1.71–1.78 mm. An additional difference is that about of the length of the posterior 3 or 4 bristles of the posteroventral infold of B. toxotes extends past the valve edge, whereas bristles in a similar position on B. californica are relatively short (compare Figure 25b with Figure 26f). Also, the stem of the sensory bristle of the 5th joint of the female 1st antenna of B. toxotes is relatively shorter than that of B. californica: the base of the proximal terminal filament of the sensory bristle of B. toxotes is proximal to the base of the c-bristle, whereas it is either opposite the base of the c-bristle, or is distal to it, on B. californica (compare Figure 25c with Figure 26g).

Synasterope Kornicker, 1975

TYPE-SPECIES.—Synasterope implumis Poulsen, 1965:421, subsequent designation by Kornicker (1975:440).

DISTRIBUTION.—Members of this genus are widespread between latitudes of about 42°N and 73°S. Known depth range 1–4450 m. The genus is reported from the Gulf of Mexico for the first time herein.

COMPOSITION.—The genus is represented in the study area by 8 species: Synasterope species 1 (Bowen et al., 1979, fig. 3); S. longiseta Poulsen, 1965:417; S. implumis Poulsen, 1965:421; S. serrata Poulsen, 1965:427; S. cushmani Kornicker, 1974a:11; S. setisparsa (Kornicker, 1958:239); S. psitticina (Darby, 1965:31); S. williamsae, new species. The key includes only species in study area.