Harbansus schornikovi (Kornicker & Caraion 1977)

Euphilomedes schornikovi

HOLOTVPE.—USNM 156644, 1 A-1 male, on slides and in alcohol.

TYPE-LOCALITY.—Thalassa station X053.

ETYMOLOGY.—The species is named after Professor E. I. Schornikov, Hydrobiological Laboratory, Institute of Marine Biology of the Far Eastern Scientific Center of the Academy of Science, Vladivostok, USSR.

MATERIAL.—“Grigore Antipa” 462, paratype, instar III female, from same station as holotype.

DESCRIPTION OF A-1 MALE (Figures 19–21).—Carapace with elongate rostrum and projecting caudal process (Figures 19, 20a,b); valve edge cutting diagonally across outer ventral corner of rostrum (Figure 20b).

Ornamentation: Surface with shallow fossae and scattered short and long bristles (Figure 19).

Infold: Rostral infold with 4–6 bristles (Figure 20b); infold just below incisur with 1 short bristle (Figure 20b); anteroventral infold with about 6 ridges but no bristles; ventral infold without bristles; posteroventral infold including caudal process with 7 bristles near inner margin of infold (Figure 20a); caudal process with “pocket” with 5 spinous bristles along upper part of inner edge (Figure 20a); outer edge of caudal process with 3 minute bristles (Figure 20a).

Selvage: Wide lamellar prolongation with marginal fringe present along anterior, ventral, and posterior margins; prolongation divided at inner end of incisur (Figure 20b).

Central Muscle Attachment Scars: Consisting of elongate and oval individual scars (Figures 19, 20c).

Size: USNM 156644, length 0.96 mm, height 0.60 mm.

First Antenna (Figure 20d): 1st joint: bare. 2nd joint: 1 dorsal and 1 ventral bristle, spines on medial surface near ventral margin and on lateral surface near terminal end. 3rd joint: 3 bristles (1 ventral, 2 dorsal). 4th joint: 4 bristles (2 ventral, 2 dorsal), and with few spines on medial surface near ventral margin; 5th joint: sensory bristle with about 6 short marginal filaments and tip consisting of 4 longer filaments. 6th joint: medial bristle about same length as 5th joint, with marginal spines. 7th joint: a-bristle about one-third longer than bristle of 6th joint; b-bristle slightly longer than twice length of a-bristle, with 1 short filament near middle and 3 terminal filaments; c-bristle slightly longer than b-bristles, with 5 marginal filaments and 1 short and 3 longer filaments at tip. 8th joint: d- and e-bristles bare, same length as c-bristle; f-bristle about same length as c-bristle, with 2 marginal filaments and 1 short and 3 long terminal filaments; g-bristle about same length as f-bristle, with 2 marginal filaments and 4 terminal filaments (1 short, 3 long).

Second Antenna: Protopodite bare. Endopodite 3-jointed (Figure 20e): 1st joint short with 2 minute bristles; 2nd joint elongate with 3 ventral bristles; 3rd joint elongate with 1 proximal ventral bristle and 2 short terminal bristles. Exopodite: 1st joint with minute medial bristle on terminal margin; joints 2–8 with fairly long distal spines forming row; joints 3 or 4 to 7 or 8 with small basal spine; bristles of joints 2–8 short with stout ventral spines; 9th joint with 3 bristles, all short (Figure 20f) (longer of these ventral and with few stout ventral spines, remaining 2 with more slender ventral spines).

Mandible (Figures 20g, 21a): Coxale endite bifurcate, without basal bristle. Basale: spinous medial side with 4 short proximal bristles near ventral margin and 1 at middle of ventral margin; ventral margin with I or 2 distal bristles; lateral side with 2 bristles near ventral margin; dorsal margin with 1 bristle distal to middle and 2 terminal. Exopodite hirsute, reaching middle of dorsal margin of 1st endopodite joint, with 2 terminal bristles. Endopodite: 1st joint with ventral bristles (2 long, 1 short); 2nd joint with 4 distal bristles on ventral margin forming 2 groups, each with 2 bristles; middle of dorsal margin with 7 bristles forming 2 groups (2 bristles in proximal group, 5 in distal group); medial side of joint with spines forming row near proximal group of bristles on dorsal margin; 3rd joint with 3 bristles and 3 claws (2 long with ventral spines, and 1 short, dorsal).

Maxilla (Figure 21b–d): Coxale with spinous dorsal bristle. Endites I and II each with about 6 bristles: endite III with 1 proximal and 7 terminal bristles. Basale with 2 long bristles on distal ventral margin. Exopodite short with 3 bristles (2 long, 1 short). Endopodite: 1st joint with 1 α-bristle with long proximal spines and 2 β-bristles; end joint with 3 a-bristles with long hairs near middle, 2 b-bristles (outer bristle with long proximal hairs and short distal spines, inner bristle clawlike, bare), 2 short slender c-bristles, and 3 stout d-bristles (Figure 21c,d).

Fifth Limb (Figure 21e,f): Epipodial appendage with 42 bristles. 3 endites with numerous bristles. Exopodite: 1st joint with main tooth obscured on specimen examined but consisting of about 4 teeth, distal margin with 2 anterior bristles, posterior bristles obscure on specimen examined, outer distal corner with hirsute lobe with spinous bristle; 2nd joint with large squarish tooth with 2 low nodes on inner edge; 3rd joint with 2 short hirsute bristles on outer lobe and 3 bristles on inner lobe (2 much longer than bristles on outer lobe); 4th and 5th joints fused, with total of 5 bristles.

Sixth Limb (Figure 21g): 1 hirsute bristle in place of epipodial appendage; endite I with 3 bristles; endite II with 3 terminal bristles; endite III with 7 terminal bristles; endite IV with 5 terminal bristles; end joint not projecting posteriorly, with 8 marginal bristles (posterior 2 bristles hirsute, remaining bristles and those of endites with long proximal hairs and short distal spines); surface of limb hirsute.

Seventh Limb (Figure 21h): No proximal bristles; distal group with 4 tapered bristles, each with 3 bells and distal marginal spines; terminus with comb of 5 teeth opposing 2 pegs.

Furca (Figure 2i): Each lamella with 6 claws: claws 1, 2, 4 primary; claws 3, 5, 6 secondary; claw 1 with teeth forming lateral and medial row along posterior margin with largest tooth medially and distally; remaining claws with teeth along posterior margins; hairs present near base of claw 1 and following claw 6.

Rod-shaped Organ (Figure 21j,k) Elongate, weak suture present proximal to middle, tip pointed; part distal to middle with wide and narrow sections but without sutures.

Eyes: Medial eye not well-defined, bare (Figure 21j); sac with many minute yellow cells in vicinity where lateral eye generally occurs may be lateral eye.

Upper Lip: Helmet-shaped with anterior process (Figure 21i)

Y-Sclerite: Type usually present in family (Figure 21i).

Genitalia: Not observed.

DESCRIPTION OF INSTAR III FEMALE (Figure 22).—Carapace similar in shape and ornamentation to that of A-1 male (Figure 22a). Infold not examined.

Size: “Grigore Antipa” 462, length 0.90 mm, height 0.45 mm.

First Antenna: Not examined in detail, but similar to that of A-1 male.

Second. Antenna: Protopodite bare. Endopodite 2-jointed (Figure 22b,c): 1st joint with 1 short bristle; 2nd joint elongate with 1 or 2 ventral bristles (1 long with long proximal and short distal spines, other bristle when present short), and 1 spinous terminal bristle. Exopodite: distal margin of 1st joint with well developed medial bristle, about one-fourth length of 2nd joint; bristles of joints 2 to 8 short, with stout ventral spines; 9th joint with 3 bristles (1 bristle same length as joints 4 to 9 combined, with 4 stout ventral spines; remaining bristles very short with short, slender, marginal spines); joints 2–8 with spines forming terminal row; small basal spines on some joints.

Mandible, Maxilla: Not examined in detail but similar to those of A-1 male.

Fifth Limb (Figure 22d): Epipodial appendage with 36 bristles. 3 narrow endites with total of about 15 bristles. Exopodite: 1st joint with main tooth with 3 teeth bearing small secondary teeth, short stout pectinate spine proximal to main tooth; 2nd joint with large square tooth, posterior side with group of 3 bristles (2 long, 1 short and pectinate); 3rd joint with inner lobe with 3 bristles, outer lobe with 2; 4th and 5th joints fused, with total of 5 bristles.

Sixth Limb: Not examined in detail but similar to that of A-1 male.

Seventh Limb: Elongate, without bristles or terminal comb (Figure 22e).

Furca, Rod-shaped Organ, Medial Eye: Similar to those of A-1 male.

Lateral Eye: Round sac with about 6 minute yellowish cells present on each side may be lateral eyes (Figure 22f).

COMPARISONS:—The new species E. schornikovi has in common with two other species (Philomedes paucichelata Kornicker, 1958, and Tetragonodon rhabdion (Kornicker, 1970) the presence of only 6 claws on the furca with the 3rd claw being smaller than the 4th. The three species should probably be referred to a new genus. E. schornikovi differs from P. paucichelata in having 2 bristles instead of 1 on the 2nd joint of the 1st antenna, and in having a long terminal bristle on the 2nd joint of the endopodite of the female 2nd antenna. (The terminal ends of the endopodites of several specimens of Philomedes paucichelata from Charlotte Harbor, Florida, examined by the senior author were either bare or bore a minute bristle.) E. schornikovi differs from T. rhabdion in having a well developed rod-shaped organ and a long terminal bristle on the 2nd joint of the endopodite of the female 2nd antenna. Some species of Pseudophilomedes also have only 6 furcal claws, but the 2nd exopodial joint of the female 5th limb of members of that genus is prolonged, not short as on E. schornikovi.

Tetragonodon Brady and Norman, 1896

One species of Tetragonodon was collected, T. ctenorynchus (Brady, 1887), which is the type-species of the genus. The male of the species is described for the first time. The male of the genus was previously unknown. Of particular interest is the fact that the sensory bristle of the male 1st antenna bears proximal filaments in a cup not unlike that on the sensory bristle of males in the family Sarsiellidae.

DISTRIBUTION.—Only three species of the genus are known. One species lives along the western coast of Africa and Europe between latitudes 20°41′N and 38°38′N at depths of 636–2995 m; a second species lives in the Gulf of Mexico at a depth of 1000–1200 m, and a third lives in the Peru-Chile Trench at a depth of 991–1015 m. Empty valves have been collected at shallower depths (7– 152 m) in the Atlantic Ocean off Puerto Rico and in Colon Harbor, Panama. Specimens of T. ctenorynchus in the present collection are from off the northern end of the Islamic Republic of Mauritania at a depth of 1120 m. A possible fourth species from the west coast of Morocco, Tetragonodon erinaceus Brady and Norman, 1896, was correctly referred by Müller (1912:51) to “Cypridinidarum genera dubia et species dubiae.”