Vargula lusca Kornicker 1975

Vargula lusca

HOLOTYPE.—USNM 128056, gravid ♀, length 2.79 mm. Valves and some appendages in alcohol, remaining appendages on slides.

TYPE-LOCALITY.—Eltanin Cruise 27, station 1981, subantarctic.

ETYMOLOGY.—The specific name “lusca” from the Latin “luscus” [= one-eyed, half-blind] refers to the absence of lateral eyes.

MATERIAL.—Holotype.

DIAGNOSIS.—Carapace length of female, about 2.79 mm. Caudal process narrow or not evident.

Seventh limb: Single spinous peg present opposite comb.

Furca: Claws 2 and 4 of female continuous with lamella.

Upper lip: Posterior margins of tusks with glandular openings forming narrow steps.

Lateral eye: Absent.

DESCRIPTION OF FEMALE.—Carapace elongate with convex dorsal and almost linear ventral outline in lateral view (Figure 104a); incisur narrow, deep (Figure 104g); posterior with small projecting caudal process (Figure 104b); on left valve of holotype, upper end of caudal process defined by concavity where merging with posterior margin of valve above caudal process; on right valve concavity less evident and posterior margin evenly rounded.

Infold (Figure 104c-f): Infold behind rostrum with about 15 or 16 bristles, some double; inner corner of incisur with usual 2 bristles; lower margin of incisur with 1 or 2 short bristles near inner corner and row of about 30 long double bristles forming row on list along anteroventral infold; 2 or 3 bristles observed on list along ventral margin. Posterior infold: crescent shaped, extending from ventral margin to point located on posterior margin at about one-half to three-fourths of valve height; ridge along inner margin of crescent with about 16 minute bristles; ridge on right valve broadening near upper part (Figure 104c); pores present along outer edge of crescent.

Selvage: Similar to that on V. subantarctica.

Muscle scars: Central muscle scars consisting of about 16 individual scars.

Size (Figure 82): USNM 128056, length 2.79 mm, height 1.75 mm.

First antenna: Distal lateral surface of 1st joint with short spines forming clusters oblique to dorsal margin; 2nd joint with spines forming clusters on ventral and dorsal margins and medial and lateral surfaces; 3rd joint with 2 spinous bristles, 1 dorsal near middle, 1 ventral terminal; medial surface with clusters of short spines; 4th joint with 2 spinous terminal bristles, 1 ventral, 1 dorsal; sensory bristle of 5th joint with 10 long proximal and 3 shorter distal filaments, some proximal filaments finely pectinate; medial bristle of 6th joint with spines, shorter than a-bristle of 7th joint. Seventh joint: a-bristle with widely separated small marginal spines; b-bristle with 5 short filaments, some pectinate; c-bristle broken, 8 filaments on remaining part, some pectinate. Eighth joint: d- and e-bristles bare, about twice length of b-bristle; f- and g-bristles long with 12 filaments, including tip, some filaments pectinate.

Second antenna (Figure 104h,i): Protopodite with short spinous medial bristle. Endopodite 3-jointed: 1st joint with 4 proximal bristles, 1 longer than others, and 1 medium length distal bristle with faint marginal spines; 2nd joint with 1 bristle reaching beyond distal end of 3rd joint; 3rd joint with long terminal filament. Exopodite: ventral margin of bristle of 2nd joint with 8 or 9 stout spines; joints 3 to 9 with basal spines; 2nd joint with short spines along ventral margin; 9th joint with 4 bristles, 1 short bare, 3 long with natatory hairs and without spines; joints 2 to 8 with faint short spines along distal margins; bristles on joints 3 to 8 with natatory hairs.

Mandible (Figure 104j-l): Coxale endite spinous with small bristle near base; peg present between 2 stout terminal spines of endite. Basale: ventral margin with 2 a-bristles, 1 b-bristle, 2 c-bristles, and 2 d-bristles (Figure 104j); dorsal margin with 3 spinous bristles, 1 distal to middle, 2 terminal. Exopodite reaching end of 1st endopodite joint and with 2 spinous bristles, inner bristle 2 to 3 times length of outer bristle. Endopodite: ventral margin of 1st joint with 4 bristles, 2 long, 1 short, 1 minute; dorsal margin of 2nd joint with about 20 bristles, long and short, similar to those of V. subantarctica. Ventral margin of 2nd joint with 3 groups of bristles with 1, 1, and 2 bristles; medial bristle of distal pair spinelike (Figure 104k); end joint with 3 claws and 4 bristles, medial ventral bristle minute, 2 large ventral claws with rather large teeth near middle of ventral margin.

Maxilla (Figures 104m, 105a): Endite I with about 11 bristles, endite II with 5 bristles, endite III with 1 proximal and 5 terminal bristles; some endite bristles with triaenid tips; spines present on coxale near dorsal margin. Coxale with stout plumose bristle. Exopodite hirsute with usual 3 bristles, similar to that on V. subantarctica. First joint of endopodite with 2 α-bristles (outer bristle plumose to tip, inner bristle with short marginal spines), and 3 β-bristles, outer 2 pectinate, inner and shorter bristle with few spines; cutting edge consisting of rounded tooth. Second joint of endopodite with 4 a-bristles, 3 b-, c-, and d-bristles: anterior 2 a-bristles with few marginal spines, next with 12 stout spines, posterior bristle longer than others and 5 marginal spines; anterior 2 b-bristles pectinate along posterior margins, posterior b-bristle with 4 strong teeth near middle of anterior margin and 1 tooth on posterior margin; 1 short bare c-bristle, middle c-bristle with about 18 teeth along anterior margin, posterior c-bristle with 19 long teeth along anterior margin; anterior d-bristle with about 8 teeth along anterior margin, middle d-bristle with 12 teeth on anterior margin, posterior d-bristle longer than others and with about 26 teeth along anterior margin.

Fifth limb (Figure 105b): Epipodial appendage with 57 bristles; sclerotized process of protopodite with undulate margin. Exopodite: anterior margin of 1st joint with plumose bristle near protopodite process and 3 spinous distal bristles similar to those on V. subantarctica; main tooth with 6 teeth, proximal peg and spinous bristle; 2nd joint with 1 posterior c-bristle, 1 anterior d-bristle, 4 a-bristles, 4 b-bristles, and 3 b′-bristles; inner lobe of 3rd joint with 1 proximal plumose bristle and 2 longer terminal bristles with short marginal spines; outer lobe of 3rd joint with 2 bristles (outer bristle with long proximal and short distal spines, inner bristle with short marginal spines); 4th joint separated from 5th by suture; 4th joint with 4 spinous bristles; 5th joint with 2 spinous bristles; small spined process present on inner corner of terminal margin of 5th joint; joints 3 to 5 hirsute.

Sixth limb (Figure 105c): Smaller than 6th limb of V. subantarctica, but with similar distribution of bristles, except all bristles of end joint with long proximal and short distal spines except posterior 2, which are plumose; total number of bristles on end joint 10 or 11.

Seventh limb: Each limb with 25 or 26 bristles, 12 or 13 in distal group (6 or 7 ventral, 6 dorsal), and 12 to 14 in proximal group (5 or 6 ventral, 7 or 8 dorsal); each bristle with 1 to 6 bells; terminal ventral comb with 7 elongate teeth; 4 or 5 short square-tipped teeth present on either side of elongate teeth; single peg with spines near tip present opposite comb (Figure 105d).

Furca: Similar to V. subantarctica.

Rod-shaped organ and eyes (Figure 105e): Medial eye and rod-shaped organ similar to that of V. subantarctica. Lateral eyes absent.

Upper lip: Similar to that of V. subantarctica except for glandular openings along posterior margins of tusks which form narrower horizontal steps.

Genitalia: See Figure 105f.

Eggs: USNM 128056 with 19 eggs in brood chamber.

Parasites: Appendages of USNM 128056 with numerous ovoid protistans.

COMPARISONS.—The new species V. lusca is closely related to V. antarctica and V. subantarctica. It differs from both species in lacking lateral eyes. Its carapace is also smaller than that of V. antarctica. The posterior margin of the tusks on the upper lip of V. lusca is not as steplike in lateral view as the tusks of V. subantarctica. The tusks of V. lusca do not bear the inner tooth present on V. dentata. The furca of V. lusca differs from that of V. sutura in having the 2nd and 4th claws united to the lamella. The 7th limb of V. lusca does not have the hooklike process present on the 7th limb of V. hamata.

DISTRIBUTION.—This species was collected only at the type-locality south of Tasmania at a depth of 910–915 m (Figure 83).