Eusarsiella bakeri Kornicker 1986

Eusarsiella bakeri

ETYMOLOGY.—This species is named for James H. Baker.

HOLOTYPE.—USNM 154183, ovigerous female on slides and in alcohol.

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

PARATYPES.—Southwest Florida continental shelf: 1 ovigerous female, sta 4; 3 ovigerous females, 2 adult females, 1 juvenile, sta 22; 2 adult females, sta 24; 4 ovigerous females, 4 adult females, 1 juvenile, 1 specimen, sta 28. Louisiana continental shelf, 1 ovigerous female, sta THR-2. Texas continental shelf: R/V Gyre cruise 11, USNM 158179, 1 ovigerous female, USNM 158172, 158177, 2 females, sta 8; USMN 158175, 2 adult females, sta 9; USNM 158174, 1 adult female, sta 11; USNM 158117, 1 ovigerous female, USNM 158173, 2 adult females, sta 12. R/V Longhorn, USNM 193110, 1 stage IV male, sta 3; USNM 193109, 1 adult female, 2 ovigerous females, sta 6. Transect SB, adjacent to Southern Bank, USNM 193111, 1 adult female, sta 3.

DISTRIBUTION.—Gulf of Mexico, on continental shelf off Florida, Louisiana, and Texas (Figure 4). Known depth range 51.75–91 m (Table 1).

DESCRIPTION OF ADULT FEMALE (Figures 96–98; PLATES 31–34).—Carapace oval in lateral view with elongate caudal process and without rostrum or incisur (Figure 96; Plates 31a,b, 32 a,c).

Ornamentation (Figures 96, 97b; Plates 32b,d, 33, 34): Continuous oval ridge composed of shell present on each valve approximately parallel to outer margin except for posteroventral corner in vicinity of caudal process (Figure 96, Plate 31a); ridge bearing about 7 small processes along posterior and posteroventral edge, the posterior 2 being larger than others (Figure 96; Plates 31a, 34a); ridge and processes with minute papillae (Plate 33c); long bristles distributed along oval ridge and along anterior and ventral margins of valves (Plates 31, 34c,d); surface of valves with small flat-bottomed fossae (Plates 32b,d, 33a,b, 34a,b); an inward pointing row of 5–10 short processes present around perimeter of fossae except in vicinity of central muscle attachment and valve edges where processes around perimeter of fossae are smaller and more numerous (Plates 32b, 33b); some fossae coalesce to form large fossae (Figure 97b); 5 processes present along posterior edge of valve and 2 smaller processes along ventral edge anterior to caudal process (Figure 96; Plate 31a,b); short bristles or papillae along anterior margin of valve with bulbous tips covered by minute knobs (Plate 33d). Surface of valves not coated with gelatinous film.

Infold (Figure 97a): Anterior infold with minute bristle near inner edge just below middle of anterior valve margin; infold of caudal process with 4 small bristles and 1 bristle near inner edge of infold; posterior infold with 2 setose bristles; 1 small bristle near inner edge of infold just anterior to caudal process.

Central Adductor Muscle Attachments (Figure 97c): Consisting of about 12 oval attachments visible on inner side of valve.

Size: USNM 154183, length including caudal process 0.83 mm, length excluding caudal process 0.80 mm; height including caudal process 0.67 mm, height excluding caudal process 0.64 mm. USNM 158117, length including caudal process 0.89 mm, length excluding caudal process 0.82 mm; height including caudal process 0.76 mm, height excluding caudal process 0.68 mm. USNM 158172, length including caudal process 0.83 mm, length excluding caudal process 0.82; height including caudal process 0.71 mm, height excluding caudal process 0.66 mm.

First Antenna (Figure 97d): First joint bare. Second joint with 1 dorsal bristle. Third and fourth joints fused; third joint with long dorsal bristle and shorter ventral bristle; fourth joint with short dorsal bristle and 2 longer ventral bristles. Sensory bristle of fifth joint with 2 minute filaments, 1 proximal, 1 near middle. Sixth joint with short medial bristle. Seventh joint: a- bristle with few spines, about same length as fifth joint; b-bristle bare, shorter than a-bristle; c- bristle about same length as sensory bristle of fifth joint, with 3 small marginal filaments. Eighth joint: d- and e-bristles bare with blunt tips, slightly shorter than c-bristle; f-bristle shorter than c-bristle, with 1 or 2 minute filaments; g-bristle about same length as c-bristle, with 3 minute marginal filaments.

Second Antenna (Figure 97e): Protopodite bare. Endopodite with 2 proximal anterior bristles and short terminal protuberance. Expodite: first joint with small medial bristle on terminal margin; bristle of second joint with slender ventral spines and distal natatory hairs; bristles of joints 3–8 with few slender, proximal, ventral spines and natatory hairs; ninth joint with 1 long bristle with natatory hairs and slender, proximal ventral spines, and 1 short bare dorsal bristle.

Mandible (Figure 97f,g): Coxale with proximal medial spine and fringe of hairs along ventral margin (Figure 97f): Basale: 4 small bristles near ventral margin; dorsal margin with minute subterminal spine. Endopodite: first joint: medial surface with medial spines; dorsal margin with small spines forming terminal row; ventral margin with stout terminal claw; second joint with stout terminal claw on ventral margin; dorsal margin with minute subterminal bristle; end joint with stout terminal claw with minute ventral and dorsal bristle near base.

Maxilla (Figure 97h): Coxale with short dorsal bristle; 3 endites with total of about 14 bristles. Basale with 1 short bristle near exopodite. Exopodite with 2 bristles, 1 of these more than length of other. Endopodite: first joint with spinous alpha- and beta-bristles; end joint with 2 a-bristles, 1 c-bristle, and 5 pectinate end bristles.

Fifth Limb (Figure 97i): Single endite with 1 short bristle. Exopodite: first joint lobate with 2 bristles; second to fifth joints fused, hirsute with total of 8 bristles.

Sixth Limb (Figure 98a–c): Single endite with 3 short bristles; end joint with 7–10 spinous bristles and 3 posterior hirsute bristles; long hairs present in vicinity of posterior margin of end joint.

Seventh Limb (Figure 98d): Two proximal bristles present, each with 4 or 5 bells; 6 distal bristles, 3 on each side, with 2–6 bells; terminus with opposing combs, each with 3 or 4 teeth.

Furca (Figure 98e): Each lamella with 5 claws; claw 1 continuous with lamella, claws 2–5 separated from lamella by suture; posterior margins of claws with pointed teeth, some longer than others; 2 slender spines on lamella following claw 5 on right lamella, about 5 on left.

Bellonci Organ (Figure 98f,g): Elongate, broadening distally with rounded tip.

Eyes (Figure 98f,g): Lateral eyes unpigmented, small, with about 8 minute yellow globules (ommatidia?) Medial eye unpigmented bare, larger than lateral eye.

Brush-like Organ (Figure 98e): Consisting of several minute bristles near genitalia.

Y-Sclerite (Figure 98e): Normal for family.

Posterior of Body: Bare, without processes.

Eggs: USNM 154183 with 3 eggs; USNM 158117 with 2 eggs and small, unextruded eggs.

COMPARISONS.—The oval ridge on each valve of the new species E. bakeri differs from that of E. cornuta Poulsen, 1965, in being narrower in the posterior half, in having smaller posterior processes, and in not having anterior processes. Also, the fossae of E. bakeri are without the central pore present in the fossae of E. cornuta, and the shell surface between fossae of E. bakeri is not punctate like that of E. cornuta. The long teeth on claw 1 of the caudal furca of E. bakeri are sharply pointed, not blunt as on E. cornuta. The carapace of E. bakeri differs from that of E. gettlesoni in having more processes on the oval ridge, in having a longer caudal process, and in having more and smaller inward pointing processes along the perimeters of the fossae within the oval ridge (except for the fossae near the central adductor muscle attachments).