Dantya fossula Kornicker 1983

Dantya fossula

ETYMOLOYG.—The specific name from the Latin fossula diminutive of fossa, meaning ditch, in reference to the numerous fossae on the carapace.

MATERIAL.—Station 110, R/V Benthédi; 12°–25′36″S, 46° 16′12″E; south part of Zélée Bank, Mozambique Channel; 10 Apr 1977; depth 24 m; collected with suction device equipped with 1 mm net by Centre National de Tri d'Océanographie Biologique (CENTOB), France; received from Dr. Michael Segonzac: holotype, adult female on slide and in alcohol; unique specimen; deposited in the Muséum National d'Histoire Naturelle, Paris, France.

DESCRIPTION OF ADULT FEMALE (Figures 1–3).—Carapace elongate, with narrow rostrum overhanging incisur, and with projecting caudal process (Figure 1).

Ornamentation (Figures 1, 2a): Each valve with several ribs: dorsal rib extending from upper edge of rostrum to posterodorsal corner of valve; upper lateral rib extending from lower margin of rostrum to posterodorsal corner of valve; lower lateral rib extending from anteroventral corner of valve to lower edge of caudal process; upper and lower lateral ribs connected by vertical rib midway between incisur and central adductor muscle attachment; slender vertical rib extending from vicinity of central adductor muscle attachment to dorsal rib; narrow, crenulate, ventral ridge extending from upper lateral rib in vicinity of incisur to caudal process; 3 or 4 radial ribs connecting ventral rib with lower lateral rib (Figure 1). Surface with abundant shallow fossae containing minute pustules; two minute bristles present at inner end of incisur (Figure 2a); bristles sparsely distributed over valve surface and more numerous along ventral margin; 2 bristles present on inner side of rostrum near its ventral margin (Figure 2a).

Infold (Figure 2a,b): Rostral infold with 3 spinous bristles forming row along edge of valve that lies near posterior end of rostrum (Figure 2a); infold of caudal process with 8 broad spinous bristles forming row along edge of lip near anterior part of process, and 2 small bare bristles near posterior edge of process (Figure 2b); anteroventral infold with short bristle.

Selvage (Figure 2a,b): Wide lamellar prolongation along anteroventral and ventral margins; prolongation bearing long streamers in vicinity of anteroventral corner but not elsewhere; anteroventral selvage terminating near ventral bristle on infold of rostrum; margin of selvage between ventral bristle and anteroventral corner of valve with narrow fringe but no long streamers; dorsal selvage extending from anterodorsal corner of rostrum to anterior juncture of hingement broad with marginal fringe; lamellar prolongation absent at bases of 3 bristles on rostral infold; posterior edge of caudal process without lamellar prolongation.

Size: Holotype, length 1.01 mm, height 0.50 mm.

First Antenna (Figure 2c): 1st joint bare. 2nd joint with dorsal midbristle. 3rd joint short, not separated from 4th joint by suture, with 2 bristles (1 ventral, 1 dorsal); 4th joint elongate, with 3 spinous bristles (2 ventral, 1 dorsal). 5th joint elongate; sensory bristle with 4 marginal filaments and minute process at tip. 6th joint minute, fused to 5th joint; medial bristle longer than 5th joint and with faint marginal spines. 7th joint: a-bristle about twice length of 5th joint, with spines along ventral margin; b-bristle about same length as a-bristle, with short filament distal to middle and minute process at tip; c-bristle same length as sensory bristle of 5th joint, with 4 marginal filaments and minute process at tip. 8th joint: d-and e-bristles bare, about same length as c-bristle, with blunt tips; f-bristle shorter than c-bristle, with 2 proximal filaments, 2 smaller spine-like distal filaments, and minute process at tip; g-bristle about same length as c-bristle, with 5 marginal filaments and minute process at tip. Filaments on sensory bristle and on b-, c-, f-, and g-bristles with spine-like, drawn-out tips.

Second Antenna (Figure 2d): Protopodite bare. Endopodite 2-jointed: 1st joint with 2 short proximal anterior bristles; 2nd joint small with 1 fairly long spinous bristle (tip of bristle broken off on illustrated limb). Exopodite: 1st joint elongate with minute terminal recurved bristle; 2nd joint with fairly long medial spines forming 2 fan-like arrangements on distal margin; similar spines forming single fan-like arrangements on joints 37; joints 4–8 with basal spine (spines similar in size, except that of joint 4 being slightly smaller); basal spine of 8th joint longer than small 9th joint; bristle of 2nd joint with slender proximal ventral spines and few smaller slender distal spines on both ventral and dorsal margins; bristles of joints 3–8 with stout proximal ventral spines, proximal dorsal hairs, and distal natatory hairs on both margins; 9th joint with 2 bristles (longer of these only slightly longer than combined lengths of joints 2–9; smaller bristle about half that length; longer bristle with few small, proximal spines).

Mandible (Figure 2e): Coxale endite consisting of stout pointed process with long proximal hairs and stout distal spines; ventral margin of coxale with long hairs. Basale: dorsal margin with 1 short ringed bristle distal to middle and 2 terminal bristles (1 long, 1 short); medial side with 2 small bristles near ventral margin; lateral side with 3 small bristles near ventral margin; ventral margin with 1 small proximal bristle. Exopodite minute, with 1 terminal bristle reaching well past middle of dorsal margin of 1st endopodial joint. 1st endopodial joint: dorsal margin with terminal spines forming row; ventral margin with 1 small bristle and 2 stout claws (proximal claw spinous; distal claw with about 9 slender teeth). 2nd endopodial joint: dorsal margin with 3 bristles near middle; ventral margin with 2 stout claws (proximal of these spinous; other with proximal ventral teeth); medial side with spines forming rows; minute spines present on ventral margin at base of distal claw; lateral side with small bristle near base of distal claw; medial surface with spines forming rows. 3rd endopodial joint with 2 long stout claws with proximal teeth on ventral margin, 2 ringed lateral bristles near ventral margin, 1 short spinous dorsal claw, and 1 small faint medial spine-like bristle adjacent to short dorsal claw.

Maxilla (Figure 2f): 3 endites with total of about 16 claws and bristles. Basale with bristle near middle of distal medial margin (not shown on illustrated limb). Exopodite with 3 bristles (2 long, 1 slightly shorter). Endopodite: 1st joint with distal anterior spines and a spinous alpha-and beta-bristle (alpha-bristle more slender than beta-bristle); end joint with 1 small medial c-bristle, 2 fairly long, spinous a-bristles, and 5 short, stout, terminal bristles (outer of these with slender proximal teeth and distal spines, others with stout proximal teeth).

Fifth Limb (Figure 3a–c): Epipodial appendage with 37 bristles. Three endites present: endite I with 2 short bristles; endite II with 4 spinous bristles; endite III with 4 or 5 bristles. Exopodite: 1st joint with small proximal inner lobe (with small bristle), and large rounded tooth; 2nd joint with large triangular tooth and about 4 bristles (3 along proximal outer edge, 1 close to inner edge); 3rd joint with 2 short bristles on outer lobe (no inner lobe observed); 4th and 5th joints fused, with total of 4 bristles.

Sixth Limb (Figure 3d): 4 endites present: endite I with 3 short bristles; endite II minute, with 2 bristles; endite III with 5 bristles; endite IV with 3 or 4 bristles; end joint with 7 bristles (4 anterior bristles with short marginal spines; followed by 2 bristles with long proximal hairs and short distal spines; posterior 2 bristles with long marginal hairs); a single ringed bristle on posterior margin interpreted as being epipodial bristle; medial surface of limb hirsute.

Seventh Limb (Figure 3e,f): Each limb with 3 proximal bristles, each with up to 4 bells, and 6 terminal bristles (3 on each side) with up to 6 bells; terminus consisting of comb with about 5 teeth opposite 2 short faint pegs.

Furca (Figure 3g): Each lamella with 6 claws; claw 4 stouter than claw 3; claw 1 fused to lamella, remaining claws separated from lamella by suture; teeth along posterior margin of claw 1 consisting of 3 sets, each with 6–10 teeth (not all shown on Figure 3g) increasing in length distally; the 3 sets of teeth followed by about 12 small teeth of equal length; anterior margin of lamella and medial surface proximal to claw 1 with long hairs forming clusters; remaining claws with teeth along anterior and posterior margins. (Number of teeth on claws not shown accurately in illustrated lamella.)

Bellonci Organ (Figure 3i, j): Elongate, with about 10 proximal sutures; tip rounded.

Eyes: Lateral eyes small, each with 5 light amber, divided ommatidia (Figure 3h,i). Medial eye about same size as lateral eye, unpigmented (Figure 3i).

Upper Lip (Figure 3k): Rounded with minute spines.

Brush-like Organ (Figure 3l): Consisting of about 5 minute bristles in vicinity of genitalia.

Y-Sclerite (Figure 3l): Branching distally.

Eggs: Holotype with 1 egg in marsupium.

COMPARISONS.—The new species D. fossula differs from Dantya magnifica Kornicker and Cohen, 1978:493, in having a rostrum that overhangs the incisur, forming an acute angle with the anterior margin of the valve ventral to the rostrum, not a right-angle as on D. magnifica. Also, the surface of D. magnifica bears reticulations and knob-like processes absent on D. fossula.