Eusarsiella uncus Kornicker 1986

Eusarsiella uncus

Sarsiella sculpta.—Kornicker, 1958:252, figs. 47:6A,B; 82:D,E; 88:D,K,E,O,S.

Eusarsiella sculpta.—Poulsen, 1965:92 [applies to Kornicker's specimens only].

Not Sarsiella sculpta Brady, 1890:516.

Not Sarsiella sculpta sensu Darby, 1965:34 [= Sarsiella radiicosta Darby].

ETYMOLOGY.—The specific name from the Latin uncus (hook, barb, angle), in reference to the hook-like margins of the tip of the seventh limb of this species.

HOLOTYPE.—USNM 156713, 1 adult female on slides and in alcohol.

TYPE-LOCALITY.—Card Sound, Florida.

PARATYPE.—USNM 122915, 1 adult female.

DISTRIBUTION.—Card Sound, Florida, Bimini, Bahamas (Figure 4). Known depth range 2–20 m (Table 1).

DESCRIPTION OF ADULT FEMALE (Figures 83–85; Plates 22, 23).—Carapace oval in lateral view with projecting, triangular, caudal process, and bulbous posterodorsal area (Figure 83; Plate 22a–c). Anterior and ventral valve margins distinctly crenulate (Figure 83; Plate 22a).

Ornamentation (Figures 83, 84a; Plates 22, 23): Each valve with low narrow upper and lower ribs (Figure 83; Plate 22a); surface of valves with shallow but distinct fossae (Plates 22, 23c); long hairs scattered over valve surface and along anterior margin (Figure 84a; Plates 22, 23a,b); some bristles emerging from closed pore with narrow peripheral lip (Plate 23a); bristles may have ribbed flattened proximal part and minute pore (Plate 23b); bottoms of fossae and valve surface between fossae with minute processes (Plates 22d–f, 23a,c–f); posterior part of dorsal margin with 2 minute processes (Figure 83; Plate 22a); posterior margin with 4 minute processes (Figure 83; Plate (22a,d).

Infold: Anterior infold with minute bristle near inner edge (Figure 84a); infold of caudal process with 10 or 11 slender bristles forming row (Figure 84b,c); infold anterior to caudal process with minute bristles forming groups of 1–3 bristles along inner margin of infold (Figure 84b); posterior infold with 2 setal bristles dorsal to caudal process (Figure 84b).

Selvage: Wide lamellar prolongation with smooth outer edge present along anterior and ventral valve margins.

Size: USNM 156713, length 1.65 mm, height including caudal process 1.47 mm, height excluding caudal process 1.42 mm. Measurements given by Kornicker (1958:252) of 2 females: length 1.65 mm, height 1.45 mm; length 1.54 mm, height 1.31 mm.

First Antenna (Figure 84d,e): First joint bare. Second joint with 1 dorsal bristle with few short marginal spines. Third and fourth joints fused; third joint short with 2 bristles (1 short, ventral, 1 longer, dorsal); long fourth joint with 4 bristles (3 ventral, 1 dorsal). Sensory bristle of long fifth joint with 2 minute marginal filaments. Bristle of minute, fused, sixth joint with 1 short medial bristle. Seventh joint: a-bristle bare, about twice length of bristle of sixth joint; b-bristle about one-third longer than a-bristle, with 1 minute marginal filament; c-bristle extending slightly past sensory bristle of fifth joint, with 3 minute marginal filaments. Eighth joint: d- and e-bristles bare with blunt tips (d-bristle about twice length of b-bristle, e-bristle shorter than d-bristle); f-bristle about same length as d-bristle, with 1 minute filament near tip; g-bristle only slightly shorter than c-bristle, with 2 minute marginal filaments.

Second Antenna: Protopodite bare. Endopodite 1-jointed with 1 short proximal anterior bristle and small terminal node bearing 1 minute bristle (Figure 84f). Exopodite: first joint with minute, medial, terminal bristle (appearing to have open tip); bristle of second joint about twice length of combined exopodial joints 2–9, with 10 or 11 stout, proximal, ventral spines and distal natatory hairs; bristles of joints 3–8 with stout, proximal, ventral spines and distal natatory hairs; ninth joint with 2 bristles (1 long with proximal ventral spines and distal natatory hairs, 1 shorter and with few short marginal hairs); a few minute spines observed along distal margin of joints 5–7.

Mandible (Figure 84g): Coxale endite consisting of small spine (broken off on illustrated limb); ventral margin of coxale with slender spines and hairs. Basale: 6 bristles present in vicinity of ventral margin; dorsal margin with 1 minute bristle near middle and 2 small terminal bristles. First endopodial joint: medial surface with numerous spines; ventral margin with stout terminal claw. Second endopodial joint with minute dorsal bristle and stout ventral claw. End joint with stout terminal claw and 3 minute bristles (1 dorsal, 2 ventral).

Maxilla (Figure 84h,i): Endites I—III with about 6, 4, and 5 bristles, respectively. Coxale with short bare bristle on distoanterior margin. Exopodite with 3 bristles (1 long, 2 short). Endopodite: first joint with stout spinous and pectinate alpha- and beta-bristles; second joint with 2 small a-bristles, 1 small c-bristle, and 5 pectinate end bristles.

Fifth Limb (Figure 85a): Single endite with 1 small bristle. Exopodite: first joint with 2 spinous bristles; remaining joints not well defined; second joint with 3 long terminal bristles and 1 small proximal bristle (the latter could be interpreted as being on third joint); joints 3–5 with total of 6 bristles.

Sixth Limb (Figure 85b): Single endite with 3 bristles (2 short, 1 long). End joint projecting posteriorly; ventral margin with 12 bristles with short marginal spines followed by space, and then 2 stout hirsute bristles.

Seventh Limb (Figure 85c): Each limb with 6 or 7 proximal bristles (3 or 4 on each side), and 6 terminal bristles (3 on each side); each bristle with up to 7 bells. Terminus having V-shaped opening with 2 to 4 stout teeth distally on each margin, giving hook-like appearance to each margin.

Furca (Figure 85d): Each lamella with 5 claws followed by 4 or 5 small, stout, spines; claw 1 fused with lamella, remaining claws separated from lamella by suture; posterior margin of claws with groups of teeth forming row, some teeth longer than others.

Bellonci Organ (Figure 85e): Elongate broadening distally, with rounded tip.

Eyes (Figure 85e): Medial eye bare, lightly pigmented. Lateral eye smaller than medial eye, lightly pigmented, with 5 ommatidia.

Upper Lip (Figure 85e): Helmet shaped.

Anterior of Body (Figure 85e): Triangular process present between medial eye and upper lip.

Y-Sclerite (Figure 85f): Typical for genus.

Eggs: USNM 156713 with small unextruded eggs (Figure 85f).

Gut Content: USNM 156713 with crustacean fragments in gut (including urosome of adult female harpacticoid copepod; identified by T.E. Bowman, 1976; Figure 85f).

Epiphytes: Valves of USNM 156713 with diatoms attached by short thin thread (Plates 22d,f, 23c–f).

COMPARISONS.—The deep V-shaped angle of the terminus of the seventh limb of E. uncus with its hook-like margins differs from that of other species in the genus. Also, the elongate posterior projection of the sixth limb proximal to the 2 hirsute bristles is unusual. The shape and ornamentation of the carapace easily distinguishes E. uncus from many other species of Eusarsiella. Several specimens similar in lateral outline to Eusarsiella uncus were collected on the east Florida shelf and on the East Flower Garden off Texas. The specimens are smaller (length 1.44 mm), have 2 rather than 1 proximal bristle on the endopodite of the female second antenna and are lacking horizontal ribs on the carapace. Remaining appendages, including the seventh limb, are similar to those of E. uncus. The specimens are to be tentatively considered an undescribed species.