Eusarsiella gettlesoni Kornicker 1986

Eusarsiella gettlesoni

ETYMOLOGY.—The species is named after its collector, David Gettleson, Texas A & M University.

HOLOTYPE.—USNM 154182, ovigerous female in alcohol.

TYPE-LOCALITY.—R/V Gyre cruise 11, station 7, Gulf of Mexico, off Galveston, Texas, water depth 53 m.

PARATYPES.—Louisiana continental shelf: 1 specimen, sta THR-1; 2 ovigerous females, 2 adult males, and 1 specimen, sta THR-2; 1 ovigerous female, sta THR-3. Texas continental shelf: R/V Gyre, cruise 10: USNM 154184, 1 adult female, USNM 156884, 1 specimen, sta 8; USNM 156904, 2 specimens, sta 16. Cruise 11: USNM 156819, 1 juvenile, USNM 156891, 2 specimens, USNM 156892, 1 specimen, sta 5; USNM 156824, 156825, 2 adult males, USNM 156826, 1 ovigerous female + 2 juveniles, USNM 156878, 1 specimen, USNM 156887, 2 specimens, USNM 156889, 4 specimens, USNM 156901, 3 specimens, sta 7; USNM 156897, 2 specimens, sta 11.

DISTRIBUTION.—Continental shelf off Louisiana and Texas (Figure 1). Known depth range 50–65 m (Table 1).

DESCRIPTION OF ADULT FEMALE (Figures 79, 80, Plate 21).—Carapace oval in lateral view with prominent caudal process and without rostrum or incisur (Figure 79, Plate 21a).

Ornamentation (Figures 79, 80a, Plate 21): Continuous oval rib present on each valve approximately parallel to outer margin of valve except for posterior extension near middle of posterior end; long bristles distributed along oval rib and along anterior and ventral margins of valves; surface of valve with small flat-bottomed fossae; an inward pointing row of short bristles with broad tips present around perimeter of each fossae; surface of oval rib with numerous short bristles with bulbous tips covered by minute knobs; surface of valves between fossae with minute papillae; patches of short bristles similar to those forming perimeter of fossae are scattered over valve surface (papillae are missing from these patches); bottom of fossae bare or with few small bristles. Surface not coated with gelatinous film.

Infold (Figure 80b,c): Anterior infold with minute bristle near middle of anterior margin; infold of caudal process with 5 or 6 small bristles and 1 bristle near inner edge of infold; 1 small bristle near inner margin of infold present anterior to caudal process; posterior infold with 2 setose bristles.

Size: USNM 154184, length 0.88 mm, height including caudal process 0.72 mm, height excluding caudal process 0.70 mm; USNM 156826 length, 0.93 mm, height including caudal process 0.93 mm, height excluding caudal process 0.90 mm; USNM 156887, length 0.97 mm, height including caudal process 0.85 mm, height excluding caudal process 0.79 mm.

First Antenna (Figure 80d): First joint bare. Second joint with 1 dorsal bristle and few spines along dorsal margin. Third and fourth joints fused; third joint with long dorsal and short ventral bristle; fourth joint with short dorsal bristle and 2 long ventral bristles. Sensory bristle of fifth joint with 3 minute filaments, 1 proximal, 1 near middle, 1 subterminal; medial bristle of sixth joint short. Seventh joint: a-bristle bare, about two-thirds length of dorsal margin of fifth joint; b-bristle bare, about same length as a- bristle; c-bristle same length or slightly longer than sensory bristle of fifth joint, with 2 or 3 minute marginal filaments. Eighth joint: d- and e-bristles bare with blunt tips, slightly shorter than c-bristle; f-bristle slightly shorter than c- bristle, with 2 minute marginal filaments; g-bristle about same length as c-bristle, with 3 minute marginal filaments; c-, f-, and g-bristles terminating in minute spine.

Second Antenna (Figure 80e): Protopodite bare. Endopodite with 1 proximal bristle and short terminal protuberance. Exopodite: first joint with minute medial bristle on terminal margin; bristle of second joint with slender proximal spines along ventral margin and distal natatory hairs; bristles of joints 3–6 with natatory hairs and a few slender hair-like ventral spines; bristles of joints 7 and 8 with natatory hairs; ninth joint with 2 bristles: 1 long with natatory hairs, 1 short, dorsal, bare or with faint, short marginal spines; joints 2–8 with short spines forming row along distal margins.

Mandible (Figure 80f,n,o): Coxale with proximal medial spine and fringe of hairs along ventral margin. Basale: 5 small bristles near ventral margin; dorsal margin with 2 minute subterminal bristles. Endopodite: First joint: medial surface with numerous spines; dorsal margin with few minute terminal spines forming row extending onto medial surface; ventral margin with stout terminal claw; 1 minute medial bristle present near base of claw; second joint with stout terminal claw on ventral margin; end joint with stout terminal claw with minute ventral and dorsal bristle near base.

Maxilla (Figure 80g,p): Coxale with short dorsal bristle; 3 endites with total of 14 bristles; basale with 1 short bristle near exopodite. Endopodite: first joint with spinous alpha- and beta- bristles; end joint with 2 a-bristles, 1 c-bristle and 5 pectinate terminal bristles. Exopodite with 2 bristles, 1 of these slightly more than length of other (Figure 80p).

Fifth Limb (Figure 80h,q): Single endite with 1 short bristle. Exopodite: first joint lobate with 2 bristles; second to fifth joints hirsute, fused, with total of 7 bristles.

Sixth Limb (Figure 80i): Single endite with 3 short bristles; end joint with 7–9 spinous bristles and 2 posterior hirsute bristles; long hairs present in the vicinity of posterior margin of end joint.

Seventh Limb (Figure 80j): Two proximal bristles with up to 5 bells; 5 distal bristles, 2 on one side, 3 on other, with 3–8 bells; bells decrease in size distally; terminus with opposing combs, with about 5 faint teeth.

Furca (Figure 80k): Each lamella with 5 claws; claw 1 continuous with lamella, claws 2–5 separated from lamella by suture; claws 1–5 with teeth along posterior margins, some longer than others; faint spines along anterior margin of lamella; several very slender spines on lamella following claw 5; USNM 156826 with long stiff medial hairs at base of claw 5 and following claw 5 of left lamella.

Bellonci Organ (figure 80l): Elongate, broadening distally with rounded tip.

Eyes: Medial eye pigmented, bare (Figure 80l). Lateral eye pigmented, about same size as medial eye, with about 4 ommatidia.

Brush-like Organ (Figure 80m): Consisting of 5 minute bristles dorsal to genitalia.

Genitalia (Figure 80m): Consisting of a small kidney-shaped process on each side of body.

Y-Sclerite (Figure 80m): Normal for family.

Posterior of Body: Bare without processes.

Eggs: USNM 156826 with 2 eggs and small, unextruded eggs.

DESCRIPTION OF ADULT MALE (Figures 81, 82).—Carapace more elongate than that of female and with prominent rostrum.

Ornamentation (Figure 81): Oval ridge somewhat similar to that of female but posterior end more triangular, ridge missing in vicinity of rostrum, and ridge less well developed between the 2 posterodorsal processes than elsewhere. Fossae and bristles similar to those of female.

Infold: Not examined.

Size (measurements include caudal process): USNM 156825, length 0.89 mm, height 0.62 mm; USNM 156824, length 0.83 mm, height 0.55 mm.

First Antenna (Figure 82a): First joint bare. Second joint with single dorsal bristle. Third and fourth joints fused; third joint with short dorsal bristle and minute ventral bristle; fourth joint with 2 ventral bristles near middle of joint and 1 dorsal bristle. Fifth joint small, located ventrally between fourth and sixth joints; sensory bristle with basal cup bearing abundant slender filaments and single stout bristle with 4 slender, fairly long, filaments. Sixth joint long, with small distal medial bristle. Seventh joint: a-bristle bare, about twice length of bristle of sixth joint; b-bristle bare, slightly longer than a-bristle; c-bristle reaching slightly past tip of sensory bristle of fifth joint, with 3 marginal filaments. Eighth joint: d- and e-bristles bare with blunt tips not reaching tip of sensory bristle; f-bristle about same length as d-bristle, with 3 marginal filaments; g-bristle slightly longer than d-bristle, with 3 marginal filaments.

Second Antenna (Figure 82b): Protopodite bare. Endopodite 3-jointed: first joint with 1 proximal anterior bristle; second joint elongate with 1 short proximal bristle; third joint elongate, reflexed on second joint and much longer than it, with 2 small terminal or subterminal bristles. Exopodite: first joint with 1 small terminal, medial bristle with open tip; bristle of second joint with about 10 proximal, slender, ventral spines and natatory hairs; bristles of joints 3–7 with natatory hairs and few slender ventral spines; bristle of eighth joint and both bristles (dorsal of these short) of ninth joint with only natatory hairs; joints 2–6 with minute spines forming row along distal margin.

Mandible (Figure 82c): Coxale endite consisting of single spine; ventral margin of coxale without hairs. Basale: medial side with 4 bristles (1 near middle, 3 near ventral margin); ventral margin with 1 bristle near middle; dorsal margin with 2 subterminal bristles. Exopodite hirsute, with base on lateral side but distal part on medial side. Endopodite: dorsal margin of first joint with indentation into which exopodite fits; ventral margin with 1 long distal bristle; medial surface with spines; dorsal margin of second joint with 1 long midbristle; ventral margin with 2 subterminal bristles (1 long, 1 very short); medial surface with spines; end joint with 1 unringed, terminal claw, 1 fairly long ventral bristle, and 2 minute bristles (1 ventral and 1 dorsal to base of terminal claw).

Maxilla (Figure 82d): Limb reduced. Precoxale and coxale with fringe of dorsal hairs; coxale with single dorsal bristle. Bristles weak (obscure on limbs examined and not all shown on cited figure).

Fifth Limb (Figure 82e): Single endite with 1 short bristle. Exopodite reduced: first joint with 2 bristles; remaining joints fused, with total of about 6 bristles. Epipodial appendage with about 28 bristles.

Sixth Limb (Figure 82f): Single endite with 3 short bristles; end joint with total of 11 bristles, the posterior 2 of these more hirsute than others.

Seventh Limb (Figure 82g): Each limb with 4 terminal bristles, each with 6 or 7 bells. Terminus bare, without opposing combs.

Furca (Figure 82h): Each lamella with 5 pointed claws; long and short pointed teeth present along posterior margins of claws 1 and 2, remaining claws with mainly short pointed teeth; 3 minute spines on left lamella following claw 5.

Bellonci Organ (Figure 82i): Elongate, broadening distally with rounded tip.

Eyes: Medial eye pigmented, bare (Figure 82i). Lateral eyes pigmented, slightly larger than medial eye, each with about 8 small ommatidia (Figure 82j).

Copulatory Organ (Figure 82h): Each copulatory limb consisting of 3 lobes bearing several bristles; distal lobe with terminal sclerotized hook.

Y-Sclerite (Figure 82h): Normal for family.

Posterior of Body: Bare without processes.

COMPARISONS: The carapace of the new species E. gettlesoni resembles that of E. ozotothrix Kornicker and Bowen, 1976. The female differs from that species in not having a terminal bristle on the endopodite of the second antenna. Also, the oval rib on the valve of E. ozotothrix is mainly defined by bristles, whereas the oval rib of E. gettlesoni is mainly defined by shell.