Vargula fugax Kornicker 1994

Vargula fugax

ETYMOLOGY.—From the Latin fugax (fleet, swift).

HOLOTYPE.—Adult female on slide and in alcohol in collection of the Museum of Victoria.

TYPE LOCALITY.—Slope 32, 38°21.90′S, 149°20.00′E, Victoria, S of Point Hicks; depth 1000 m.

PARATYPES.—Slope 53: adult male with cryptoniscid isopods, on slide and in alcohol; 3 undissected specimens in alcohol (1 adult male, 2 juveniles).

DISTRIBUTION.—Slope 32, 1000 m. Slope 53,996 m.

DESCRIPTION OF ADULT FEMALE (Figures 11, 12, 110n).—Carapace with small incisur and narrow projecting caudal process near midheight (Figure 11a); ventral edge of incisur with minute triangular projection past valve edge (Figure 11f). Surface of carapace with widely spaced pits (Figure 11b,c).

Infold: Rostral infold with 23 bristles (mostly divided) forming row parallel to anterior and ventral edges of valve, 2 bristles near edge close to inner end of incisur, and 1 long divided bristle at midheight. 2 small bristles proximal to inner end of incisur (Figure 11f). Infold extending from incisur to about midlength of ventral margin with 40 bristles. List anterior to caudal process broad with broad flange with row of about 25 stout triangular spines (some bare, others with slender marginal spine) along posterior edge, 3 or 4 small spines at ventral end (Figure 11e,h), and about 15 minute triangular processes beneath flange (each of 13 processes shown as dots in Figure 11e, not shown in Figure 11h).

Selvage: Broad lamellar prolongation along anterior margin of rostrum and ventral edge of incisur, absent along dorsal margin of incisur (lamellar prolongation stippled in Figure 11g). Narrow lamellar prolongation along ventral margin of valve; selvage absent along posterior edge of caudal process. Lamellar prolongation along ventral edge of incisur and along ventral margin of valve with minute spines along distal edge (not shown).

Central Adductor Muscle Attachments: Central cluster with about 11 elongate and oval attachments (Figure 11d).

Carapace Size (length, height in mm): Holotype, 3.5, 2.2, height 63% of length.

First Antenna: 1st joint bare. 2nd joint spinous. 3rd joint with dorsal spines and 2 spinous bristles (1 dorsal at about joint length, 1 ventral, subterminal); length of ventral margin about that of dorsal margin. 4th joint with dorsal spines and 2 spinous bristles (1 dorsal, 1 ventral). 5th joint with dorsal spines at midlength; sensory bristle with 10 filaments (8 stout proximal, 2 slender distal) and bifurcate tip. Medial bristle of 6th joint short spinous, with base near dorsal margin. 7th joint: a-bristle spinous, about longer than bristle of 6th joint; b-bristle about 2 times length of a-bristle, with 5 short marginal filaments, some with spines; c-bristle about 3 times length of b-bristle, with about 9 short marginal filaments (some with spines) and bifurcate tip. 8th joint: d- and e-bristles about same length as b-bristle, bare with blunt tips; f- and g-bristles similar to c-bristle (f-bristle slightly shorter).

Second Antenna: Protopodite with short spinous medial bristle (Figures 11i, 110n). Endopodite 3-jointed (Figure 11i): 1st joint with 4 proximal bristles (1 long, 3 short) and 1 long spinous distal bristle; 2nd joint elongate with 1 short terminal bristle; 3rd joint with long terminal filament about twice length of stem. Exopodite: bristle of 2nd joint reaching just past 9th joint, with 17 stout ventral spines and about 8 small hair-like dorsal spines; bristles of joints 3–8 long with natatory hairs, no spines; 9th joint with 4 bristles (2 long and 1 medium with natatory hairs, 1 short dorsal (obscured on holotype); joints 3–8 with basal spines longer on distal joints (spine of 8th joint slightly longer than 9th joint); lateral spine of 9th joint about same length as spine of 8th joint.

Mandible: Coxale endite with 2 terminal spines stouter but about same length as other spines, with minute peg between spines (Figure 12a); small bristle present at base of endite. Basale: medial surface with distal spines near dorsal margin (Figure 12c); ventral margin with 2 a-bristles, 1 b-bristle, 2 c-bristles (longer bristle twice length of shorter d-bristle), and 2 d-bristles (long d-bristle broken off both limbs of holotype) (all bristles ringed, rings not shown in Figure 12b); dorsal margin with 1 long distal bristle and 2 subterminal bristles, all with long spines (Figure 12b,c). Exopodite spinous, about same length as dorsal margin of 1st endopodial joint, with 2 subterminal bristles (distal shorter and with few spines, proximal with many spines) (Figure 12c). 1st endopodial joint with 4 ventral bristles (2 long with long spines, 1 short with short spines, 1 minute bare). 2nd endopodial joint: ventral margin with 2 single ringed bristles and 2 terminal, ringed, paired, pointed bristles (medial slightly shorter but about same width, bare; lateral with indistinct dorsal spines (spines not shown in Figure 12d); dorsal margin with 7 long bristles (longest just reaches 3rd endopodial joint) and about 16 short bristles, most with spines; medial and ventral surfaces spinous. 3rd endopodial joint with 3 claws (dorsal claw with few teeth, others with many stout teeth) and 4 bristles (lateral dorsal bristle stouter than lateral ventral bristle, weakly ringed, clawlike with pointed tip) (Figure 12d).

Maxilla: Endite bristles of holotype obscured; endite III with short proximal bristle near base of exopodite (Figure 12e). Dorsal margin of coxale with short hirsute fringe and stout bristle with few long hairs (Figure 12e). Basale with long ventral bristle. Exopodite well developed, hirsute, with plumose proximal bristle and 2 terminal bristles (bristle closest to proximal bristle with long spines, other with short spines) (Figure 12e). 1st endopodial joint tapered, with spines along dorsal margin, narrow cutting tooth with single cusp, 2 ringed alpha-bristles (outer plumose, inner with few hairs) and 3 ringed beta-bristles (outer 2 pectinate) (Figure 12f). 2nd endopodial joint with 4 ringed a-bristles (3rd counted from anterior stout pectinate, others slender bare), 3 ringed pectinate b-bristles, 3 ringed c-bristles (smallest bare, others pectinate), and 3 pectinate d-bristles (posterior ringed, others unringed) (Figure 12g–i). Rings not shown on all ringed bristles.

Fifth Limb: With 51 exopodial bristles. Protopodial tooth elongate with rounded tip, tooth appearing sclerotized only along edge (Figure 12j). Endite I with 1 small proximal anterior bristle (Figure 12j) and 5 spinous terminal bristles; endite II with 7 spinous and pectinate bristles; endite III with 6 spinous and pectinate bristles (Figure 12k). 1st exopodial joint: main tooth with stout bare sclerotized triangular tooth and 6 pectinate teeth (largest tooth folded under in illustrated compressed left limb of USNM 193859 (Figure 12k)); stout bristle with long proximal spines proximal to triangular tooth (Figure 12k); anterior side with row of 3 bristles (with long proximal spines). 2nd exopodial joint with 4 ringed pectinate a-bristles, 4 ringed pectinate b′-bristles, 4 ringed pectinate b″-bristles, 1 posterior c-bristle with long proximal and short distal spines, and 1 anterior d-bristle with long proximal and short distal spines (Figure 12j). 3rd exopodial joint hirsute (Figure 12j): inner lobe with 1 proximal ringed bristle with long proximal spines and 2 terminal bristles with short spines (outer with spines confined to tip); outer lobe with 2 ringed terminal bristles with long proximal and short distal spines. 4th joint with 4 or 5 bristles (bristle on posterior side with long proximal spines and small distal teeth, others either bare or with short spines); few small spines but no process on edge of joint close to 5th joint (Figure 12j). 5th joint well developed but not separated from 4th joint by suture, with 2 ringed terminal bristles (1 with long proximal and short distal spines, other with only short spines) (Figure 12j). Joints 3–5 hirsute, but relatively few hairs on inner lobe of 3rd joint.

Sixth Limb (Figure 11j): With 2 epipodial bristles (bare or with short spines). Endite I with 2 spinous medial bristles and 1 spinous terminal bristle; endite II with 3 spinous medial bristles and 2 spinous terminal bristles; endites III and IV each with 1 spinous medial bristle and 3 terminal bristles (middle shorter). End joint with 15 or 16 spinous bristles (long bristles with long proximal and short distal spines; short bristles with short spines) followed by space and then 3 plumose bristles (anterior shorter, bare in distal part).

Seventh Limb: Holotype: one limb with 29 bristles (terminal group with 7 bristles on comb side and 5 on peg side (proximal ends shown in Figure 11k); proximal group with 7 bristles on comb side and 10 on peg side); other limb with 30 bristles (terminal group with 6 bristles on comb side and 6 on peg side; proximal group with 7 bristles on comb side and 11 on peg side). Each bristle with up to 7 bells. Comb with 4 short flat-tipped teeth on each side of 4 longer teeth with rounded tips (Figure 11k). Single peg with few indistinct spines opposite comb. Limb not expanded distally.

Furca (Figure 12l): Each lamella with 9 articulated claws decreasing in length and width posteriorly along lamella; all claws with teeth along posterior edge (some slightly smaller than others); claw 1 with row of medial teeth only slightly stouter than teeth along posterior edge; claw 1 of right lamella anterior to claw 1 of left lamella by width of base.

Bellonci Organ (Figure 12n): Cylindrical with rounded tip.

Eyes: Lateral eye minute, indistinct, with few light amber-colored cells, but no ommatidia (eye could be easily overlooked) (Figure 12n). Medial eye with undulate ventral edge and amber-colored area near middle (Figure 12n).

Upper Lip (Figure 12m): Anterior unpaired part with short transparent tubes on glandular openings (not shown). Paired posterior part with 2 long tapering hirsute (hairs in 3 rows: anterior, posterior, lateral) tusks with large sclerotized proximal tooth on posterior edge; tip of each tusk with small diaphanous process that may be on glandular opening; 5 or 6 small glandular openings present along posterior edge of each tusk.

Genitalia (Figure 12l): Holotype with elongate genitalia (each with attached spermatophore) on each side of body anterior to furca.

Anterior of Body (Figure 11l): Small rounded anterior process just ventral to attachments of 1st antennae.

Posterior of Body: Evenly rounded, bare.

Y-Sclerite: Typical for genus.

Eggs: Holotype with 20 unextruded eggs, 10 on each side (Figure 11a shows 6 eggs of left side as seen through shell). Diameter of typical egg 0.25 mm.

DESCRIPTION OF ADULT MALE (Figure 13).—Carapace smaller and less elongate than that of adult female (Figure 13a) and with similar surface pits (Figure 13b).

Infold: Not examined in detail but, in general, similar to that of adult female.

Central Adductor Muscle Attachments (Figure 13c,d): About 17 elongate and oval scars, some compound.

Carapace Size (length, height in mm): Slope 53: dissected paratype, 3.24, 2.23, height 69% of length; undissected paratype, 3.07, 2.05, height 67% of length;

First Antenna (Figure 13e): Joints 1–4 and 6 similar to those of adult female. 5th joint with dorsal spines at midlength (not shown); sensory bristle of 5th joint with 12 filaments (9 stout proximal, 3 slender distal) and bifurcate tip. 7th joint: a-bristle spinous (spines not shown), about twice length of bristle of 6th joint; b-bristle about twice length of a-bristle, with 5 filaments (proximal filament stout with round process followed by large diaphanous sucker (with marginal hairs) and minute node near pointed tip, next 4 filaments slender, bare except for terminal spine); c-bristle about 3 times length of b-bristle, with 9 filaments (proximal filament similar to that of proximal filament of b-bristle (paratype with large sucker of c-bristle of right limb slightly smaller than sucker of b-bristle, but opposite relationship on left limb), next 8 filaments slender, bare or with few minute proximal spines) and bifurcate tip. 8th joint: d- and e-bristles slightly longer than b-bristle, bare with blunt tips; f-bristle slightly longer than c-bristle, with 9 filaments (most with few teeth) and bifurcate tip; g-bristle with about same number of filaments (most with few small teeth) as f-bristle (tip of bristle broken off on both limbs of paratype.

Second Antenna: Protopodite and endopodite similar to those of adult female. Exopodite: bristle of 2nd joint with about 12 ventral spines and few slender subterminal hair-like dorsal spines; all 4 bristles of 9th joint with natatory hairs; branch otherwise similar to that of adult female.

Mandible: Similar to that of adult female. Long d-bristle of basale with long proximal and short distal spines.

Maxilla: Endite I broad with about 11 spinous bristles; endite II small with about 6 bristles; endite III small, obscured, with about 5 bristles. Coxale with stout dorsal bristle with many long proximal and shorter distal spines. Remaining part of limb similar to that of adult female.

Fifth Limb: Epipodite fragmented and endite bristles not counted. Protopodial tooth similar to that of adult female. Except for 2nd joint having 5 rather than 4 ringed pectinate b′-bristles, exopodial joints 1–3 similar to those of adult female. 4th exopodial joint with 4 bristles (3 anterior with short spines, 1 posterior with long proximal and short distal spines); 5th exopodial joint well developed, fused to 4th joint, with 2 bristles (both bristles of left limb of paratype with long proximal and short distal spines; 1 of the bristles on right limb with only short spines).

Sixth Limb: With 2 small epipodial bristles (bare or with short spines). Endite I with 2 or 3 spinous medial bristles and 1 spinous terminal bristle; endite II with 2 or 3 spinous medial bristles and 2 spinous terminal bristles; endite III with 1 spinous medial bristle and 3 spinous terminal bristles; endite IV with 1 spinous medial bristle and 4 spinous terminal bristles. End joint with 15–17 spinous bristles (4 or 5 of short bristles with short spines, others with long proximal and short distal spines) and then 2 stout plumose bristles. Right limb of USNM 194009 with short space between anterior bristles and 3 posterior bristles; space absent on left limb).

Seventh Limb: Paratype: one limb with 23 bristles (terminal group with 7 on comb side and 5 on peg side; proximal group with 5 on comb side and 6 on peg side); other limb with 28 bristles (terminal group with 7 on comb side and 6 on peg side; proximal group with 7 on comb side and 8 on peg side). Each bristle with up to 7 bells. Comb with 5 short flat-tipped teeth on each side of 3 longer teeth with rounded tips. Single peg (bare or with few indistinct spines) opposite comb.

Furca: Similar to that of adult female.

Bellonci Organ (Figure 13f): Tapering slightly distally, with pointed tip; amber coloring where stippled in Figure 13f

Eyes: Lateral eye minute indistinct with light amber cells (not ommatidia) (Figure 13f,g). Medial eye small but larger than lateral eye, with amber coloring (Figure 13f). (The lateral eyes of the species are difficult to see but are defined slightly better in the male. The eyes are not visible through the shell.)

Upper Lip: Similar to that of adult female.

Genitalia (Figure 13i): Large copulatory limb with sclerotized triangular tip and small ringed bristles on each side of body anterior to furca (not all bristles shown).

Anterior of Body: Similar to that of adult female.

Posterior of Body (Figure 13h): Bare, with about 7 “segments” between dorsal end of girdle and heart.

Y-Sclerite (Figure 13j): Typical for subfamily.

Parasites: Dissected adult male paratype with 2 male or juvenile cryptoniscid isopods attached to right side of body posterior.

COMPARISONS.—The upper lip of V. fugax resembles that of V. tubulata Poulsen, 1962:198, but claws 2 and 4 of the furca of the species are nonarticulated, and the 7th limb bears a stout jaw rather than a cylindrical peg and, also, has bristles distal to the base of the jaw. The combination of a long caudal process near valve midheight, all furcal claws articulated, and a proximal tooth on the tusks of the upper lip is not present on previously described species of Vargula. The adult male of V. fugax is unusual in not having filaments with small suckers on the b- and c-bristles of the 7th joint of the 1st antennae. Only Cypridinodes assymetrica Brady, 1902, has been reported previously as not having filaments with small suckers (Poulsen, 1962:278). The present species has been referred to Vargula rather than Cypridinodes because of the lack of multiple serrations posterior to the tusks of the upper lip and lack of a jaw on tip of 7th limb.