Eusarsiella vema Kornicker 1986

Eusarsiella vema

ETYMOLOGY.—The species is named for the R/V Vema.

HOLOTYPE.—USNM 156798, ovigerous female, on slides and in alcohol.

TYPE-LOCALITY.—R/V Vema Cruise 16, station V-16-65, off Cape Breton Island, Nova Scotia, Canada (46°45′N, 56°22′W).

PARATYPES.—All from same sample as holotype: USNM 158110, 158111, 2 ovigerous females; USNM 158112, 1 A-1 male; USNM 158113, 2 juveniles.

DISTRIBUTION.—Collected only at type-locality. Depth 42 m (Table 1).

DESCRIPTION OF ADULT FEMALE (Figures 99–101a–e).—Carapace oval in lateral view with projecting caudal process; posterodorsal part of each valve inflated forming large bulbous process; narrow angular ridge terminating in small posterior pointing process superimposed on each posterodorsal bulbous process; in dorsal view posterior end of processes truncate (Figures 99, 100a).

Ornamentation: Surface not coated with amorphous gel; surface bristles sparse except along valve margins; minute, short, stout spines visible on surface when viewed at high magnification (× 40 objective).

Infold (Figure 100b–d): Anterior infold with 1 minute bristle near inner margin (Figure 100b); infold of caudal process with 5–7 scattered bristles (Figure 100c–d); 2 setose bristles present on posterior infold just ventral to posterior ends of bulbous processes; several minute bristles present along inner margin of infold anterior and dorsal to caudal process.

Selvage: Broad lamellar prolongation with smooth margin present along anterior, ventral, and posterior margins of each valve; prolongation extending past caudal process with square end (Figure 100c).

Size (including caudal process): USNM 156798, length 1.28 mm, height 1.31 mm; USNM 158110, length 1.27 mm, height 1.26 mm; USNM 158111, length 1.28 mm, height 1.25 mm.

First Antenna (Figure 100e,f): First joint bare. second joint with dorsal spines and 1 dorsal bristle. Third and fourth joints fused; third joint with dorsal bristle; fourth joint with 1 dorsal and 2 ventral bristles. Long fifth joint with dorsal spines; sensory bristle with minute filament near middle and spine at tip. Minute sixth joint with small medial bristle. Seventh joint: a-bristle much longer than medial bristle of sixth joint; b-bristle about length of sensory bristle of fifth joint, with spine at tip; c-bristle same length as sensory bristle, with spine at tip. Eighth joint: d- and e- bristles bare with blunt tips; d-bristle almost same length as c-bristle; e-bristle about three-fourths length of c-bristle (broken on illustrated limb); f-bristle only slightly shorter than c-bristle, with spine at tip; g-bristle same length as c-bristle, with spine at tip.

Second Antenna (Figure 100g): Protopodite bare. Endopodite 1-jointed with 2 short, proximal, anterior bristles and 1 minute, terminal, unringed bristle. Exopodite: elongate first joint with ventral hairs forming rows and 1 small, recurved, terminal, medial bristle; bristle of second joint long, with proximal ventral spines and distal natatory hairs; bristle of third joint with few proximal ventral spines and distal natatory hairs; bristles of joints 4–8 with only natatory hairs; ninth joint with 2 bristles (1 long with few proximal ventral spines and distal natatory hairs, 1 short bare).

Mandible (Figure 100h): Coxale: endite consisting of stout process with marginal spines; ventral margin of joint with long hairs. Basale: ventral margin with 3 bristles, 1 short and 2 minute; medial side near ventral margin with 1 minute bristle; lateral side near ventral margin with 2 minute bristles; dorsal margin with 3 minute bristles (1 near middle, 2 subterminal). Exopodite absent. First endopodial joint: dorsal margin undulate proximally and with spines forming terminal row; ventral margin with or without small spine and with stout terminal claw; medial surface with scattered spines. Second endopodial joint with stout ventral claw and small dorsal bristle. Third endopodial joint with stout terminal claw and 2 small bristles (1 ventral, 1 dorsal).

Maxilla (Figure 100i): Dorsal margin of coxale with fringed lamellar prolongation and short terminal bristle. Endites I to III each with 4–6 bristles, total of about 15, some pectinate. Basale with 1 bristle near exopodite. Exopodite with 3 bristles (1 long, spinous, 2 short, bare). Endopodite: first joint with spinous and pectinate alpha- and beta-bristles; second joint with 5 pectinate end bristles, 2 slender a-bristles, and 1 slender c-bristle.

Fifth Limb (Figure 101a): Single endite with short bare bristle with open tubelike tip. Exopodite: first joint with 2 spinous bristles; second to fifth joints fused, with total of 9 spinous bristles (these probably consist of 3 on second joint; 1 outer and 3 inner on third joint, and 2 on combined fourth and fifth joints).

Sixth Limb (Figures 100j, 100b): Single endite with 1 short, stout, spinous, terminal bristle and 2 minute proximal medial bristles; end joint with 15 or 16 slender spinous bristles and 2 stout, hirsute, posterior bristles.

Seventh Limb (Figure 101c): Each limb with 8 bristles, 2 proximal (1 on each side), 6 terminal (3 on each side); each bristle with up to 5 bells. Terminus consisting of opposing combs, each with several faint teeth.

Furca (Figure 101d): Each lamella with 5 long slender claws; claw 1 without basal suture; marginal teeth on claws consisting of both long and short teeth; several spines present along lamella following claw 5.

Bellonci Organ (Figure 100e): Elongate, single jointed, with rounded tip.

Eyes (Figure 100e) Medial eye lightly pigmented, bare. Lateral eye about same size as medial eye, with brown pigment and 5 ommatidia.

Upper lip (Figure 101e): Helmet shaped.

Genitalia (Figure 100k): Oval sclerotized ring on each side of body.

Y-Sclerite (Figure 100k): Typical for family.

Eggs: USNM 156798 with 5 eggs in marsupium and several smaller unextruded eggs.

DESCRIPTION OF A–1 MALE (Figure 101f–i).—Carapace more truncate posteriorly than that of adult female; each valve with pointed process present in posterodorsal part but without inflated bulbous process present on adult female (Figure 101f).

Size: USNM 158112, length 1.13 mm, height 1.00 mm.

First Antenna: Similar to that of adult female (also without ventral bristle on third joint).

Second Antenna (Figure 101g): Protopodite and exopodite similar to that of adult female. Endopodite elongate, 3-jointed: first joint with 2 small proximal anterior bristles; second joint elongate with 3 small ventral bristles; third joint elongate with 1 small terminal bristle.

Mandible: Exopodite represented by minute bristle on distal lateral margin of basale some distance from dorsal margin (Figure 101h).

Maxilla, Fifth and Sixth Limbs: Not examined in detail but, in general, similar to that of adult female.

Seventh Limb: Absent.

Furca: Similar to that of adult female.

Bellonci Organ (Figure 101i): Similar to that of adult female.

Eyes (Figure 101i): Medial eye bare, with light amber pigment. Lateral eye about same size as medial eye, pigmented light amber, with about 10 ommatidia.

COMPARISONS.—The new species, E. vema, differs from E. gigacantha, E. greyi, and E. alata in lacking a ventral bristle on the third joint of the first antenna. It differs from E. athrix and E. absens, which also lack a ventral bristle on the third joint of the first antenna, in having a longer caudal process.