Asteropterygion thomassini Kornicker 1981

Asteropterygion thomassini Group

COMPOSITION AND DISTRIBUTION.—The species of the Asteropterygion thomassini Group and their distribution are as follows: A. thomassini, new species, Madagascar; A. spinosum (Poulsen, 1965), off Mombasa, Kenya; A. thailandicum (Poulsen, 1965), off Thailand; A. nodulosum (Poulsen, 1965), off South Africa; A. skogsbergi (Poulsen, 1965), off Mombasa, Kenya, and Mtwara, Tanzania; A. oculitristis (Darby, 1965), Atlantic Ocean from Georgia to Florida, Pacific Ocean in vicinity of Baja California, and Panama, Gulf of Mexico in vicinity of Florida and south Texas; A. hulingsi (Kornicker, 1975a), off Argentina; A. setiferum (Kornicker and Caraion, 1974), off Mauritania and Ivory Coast; A. aff. setiferum, south of Luanda, Angola, in shallow water; A. romei, new species, off Tanzania and Kenya.

Species of this group have been collected at intertidal depths and also as deep as 80 m. The type-locality of Asteropterygion setiferum is listed as 1100 m (Kornicker and Caraion, 1974:66), but in view of the many shallower records of that species, and the generally shallower depths (shelf depths) at which members of the genus are collected, I am inclined to consider the 1100 m record to be atypical, or possibly the result of error.

DIAGNOSIS.—The a-bristle of 1st antenna distinctly clawlike, usually with blunt tip recurved dorsally.

Asteropterygion thomassini

HOLOTYPE.—USNM 151161, adult male, length 2.28 mm, on slides and in alcohol.

TYPE-LOCALITY.—Sta 734, Madagascar.

ETYMOLOGY.—The species name is from that of the collector of the holotype, Dr. Bernard A. Thomassin.

PARATYPES.—Madagascar: USNM 157222, 157169, 1 ovigerous female, station 712; USNM 157223, 1 specimen, sta 224; USNM 157224, 1 ovigerous female, sta 240; USNM 157225, 2 specimens, sta 274; USNM 157226, 1 juvenile, sta 231; USNM 157227, 1 juvenile, sta 256; USNM 157228, 1 adult , sta 259; USNM 157229, 157408, 17 specimens, sta 259; USNM 157230, 1 specimen, sta 230; USNM 157231, 1 adult , sta 259; USNM 157232, 1 ovigerous , sta 259; USNM 157233, 1 ovigerous , sta 738; USNM 157234, 5 specimens, sta 738; USNM 157235, 1 juvenile, sta 191; USNM 157236, 2 specimens, sta 274; USNM 157237, 1 specimen, sta 270; USNM 157238, 2 specimens, sta 262; USNM 157239, 3 specimens, sta 272; USNM 157240, 3 specimens, sta 778; USNM 157241, 1 specimen, sta 259; USNM 157242, 1 specimen, sta 761; USNM 157243, 2 specimens, sta 261; USNM 157244, 2 specimens, sta 737; USNM 157245, 3 specimens, sta 822; USNM 157246, 1 specimen, sta 230; USNM 157247, 1 specimen, sta 236; USNM 157248, 1 specimen, sta 779; USNM 157249, 2 specimens, sta 693; USNM 157250, 1 specimen, sta 274; USNM 157251, 1 specimen, sta 224B; USNM 157252, 3 specimens, sta 621; USNM 157253, 15 specimens, sta 259; USNM 157254, 1 specimen, sta 274; USNM 157255, 1 specimen, sta 240; USNM 157256, 1 specimen, sta 616; USNM 157257, 1 specimen, sta 734; USNM 157258, 4 specimens, sta 259; USNM 157259, 1 specimen, sta 622; USNM 157260, 1 specimen, sta 257; USNM 157261, 7 specimens, sta 259; USNM 157262, 1 specimen, sta 726; USNM 157263, 1 specimen, sta 814; USNM 157264, 1 specimen, sta 172; USNM 157265, 1 specimen, sta 227; USNM 157266, 6 specimens, sta 270; USNM 157267, 1 specimen, sta 257; USNM 157268, 1 specimen, sta 228; USNM 157269, 1 specimen, sta 191; USNM 157270, 1 specimen, sta 255; USNM 157271, 2 specimens, sta 262; USNM 157272, 2 specimens, sta 878; USNM 157273, 2 specimens, sta 880; USNM 157274, 2 specimens, sta 259; USNM 157275, 1 specimen, sta 270; USNM 157276, 1 specimen, sta 259; USNM 157277, 1 specimen, sta 263; USNM 157278, 1 specimen, sta 876; USNM 157279, 1 specimen, sta 272; USNM 157280, 1 specimen, sta 270; USNM 157281, 1 specimen, sta 330; USNM 157282, 1 specimen, sta 255; USNM 157283, 1 specimen, sta 623; USNM 157284, 1 specimen, sta 228; USNM 157285, 1 specimen, sta 600; USNM 157286, 2 specimens, sta 236; USNM 157287, 1 specimen, sta 617; USNM 157288, 1 specimen, sta 240; USNM 157289, 1 specimen, sta 678. Sent to Museum of National History Paris: 1 specimen sta 172; 1 specimen, sta 227; 2 specimens, sta 263; 1 specimen, sta 691; 2 specimens, sta 712.

DISTRIBUTION (Figure 131).—Collected only in the Tuléar coral reef complex, southwest Madagascar at depths of up to 60 m.

DESCRIPTION OF ADULT MALE (Figures 143–146, Plates 138–142).—Carapace with evenly rounded ventral margin and dorsal margin tapering posteriorly (Figure 143, Plate 138a); valve highest at midlength, longest at midheight, and widest in vicinity of ventral rib; outer edge of valves fairly deeply indented except along middle part of anterior edge of rostrum; lateral protuberance projecting past lower corner of rostrum; low rib lying just within anterodorsal valve edge extending from rostrum to valve midlength; a larger rib lying parallel and ventral to anterodorsal rib extending from rostrum to just past valve midlength and terminating in 1 or 2 small processes; large midrib branching from previous rib just posterior to rostrum and extending almost to valve midlength where it branches to form 2 ribs that continue almost to posterior end of valve where each terminates in stout protuberance; a lower, very large rib lying just within and parallel to ventral margin terminating at each end in processes extending well past valve edge; 3 low vertical ribs connecting ventral rib and midrib, 1 near anterior end of valve, 2 near posterior end; 2 small backward-pointing processes present near posterior edge of valve (1 between posterior ends of branches of midrib and 1 near posterior end of lower branch of midrib) (Plates 138a–c).

Ornamentation: Surface with large fossae (Plates 138, 139a,c); single row of fossae between low anterodorsal rib and larger rib lying ventral to low rib; 2 rows of fossae between the 2 posterior branches of midrib; 3–4 rows of fossae between midrib and ventral rib; 1 or 2 rows of fossae between ventral rib and ventral edge of valve; surface of fossae with minute pustules (Plates 138d,e, 139a–d); long bristles scattered over valve surface and forming row along anterodorsal, anterior, ventral, and posterior valve margins (Plates 138b,e, 139c–f, 140); bristles more abundant along edges of rostrum and incisur; some bristles with pore near base (Plate 139e), with tube exiting from pore (Plate 140a–c), and some with papillae (Plate 140f).

Infold: Rostral infold with 18 long bristles forming row paralleling valve edge (Figure 144a, Plate 141a–d); 7 shorter bristles present between row of long bristles and anterior valve margin; several minute bristles and pores present posterior to row of long bristles; 6 small bristles present on anterodorsal infold forming continuation of row of long rostral bristles; 5 small bristles forming row present on infold posterior to inner end of incisur; list extending from anteroventral infold to near posterior end of ventral margin; 22 bristles present along anteroventral and ventral infold (these bristles ventral to list on anterior part of ventral infold and on list on posterior part of ventral infold); about 4 minute bristles or pores present on anteroventral infold near valve edge; posterior infold broad with bristles forming 3 rows (Figure 144b, Plate 141e): outer row with about 11 long and 5 shorter bristles (Plates 141e, 142a,b); middle row with about 11 slender setose bristles smaller than long bristles in outer row (Plates 141e, 142a,c,e); inner row with about 21 stout tubular bristles (about 12 of these longer than others) (Plates 141e, 142a,c,d,f,g).

Selvage: Broad lamellar prolongation present along anterior, ventral, and posterior margins (Plate 141a); fringe present on outer edge of prolongation along anterodorsal margins, posterior three-fourths of ventral margin and along posterior margin (Plate 141e,f), possibly elsewhere, but many valves apparently without fringe.

Size: USNM 151161, length 2.28 mm, height 1.70 mm; USNM 157228, length 2.43 mm, height 1.76 mm; USNM 157231, length 2.25 mm, height 1.62 mm.

First Antenna (Figure 144c): 1st joint with lateral and medial spines; second joint with 5 dorsal bristles (4 proximal, 1 distal) and spines on medial side near ventral and distal margins; 3rd joint short, triangular, with 1 short ventral bristle and 3 dorsal bristles (1 near middle, 2 subterminal); 4th joint short, with 4 terminal bristles (1 dorsal, 3 ventral (1 long, 2 short)); 5th joint triangular with stout filamentous sensory bristle; 6th joint elongate with short medial bristle. 7th joint: a-claw smooth with weak rings distally; b-bristle slightly more than twice length of a-claw, with 6 marginal filaments excluding stem; c-bristle about 3-times length of a-claw, with 20 marginal filaments excluding stem. 8th joint: d- and e-bristles bare with blunt tips, shorter than b-bristle; f-bristle curved dorsally near base, about same length as c-bristle, with 7 marginal filaments excluding stem; g-bristle with tip missing on specimen examined, remaining part about same length as c-bristle, with about 14 marginal filaments excluding stem.

Second Antenna (Figure 144d,e): Protopodite with spinous medial bristle but without spines. Endopodite 3-jointed: 1st joint with short proximal and long distal part, with 5 short proximal bristles; 2nd joint elongate with 5 distal ventral bristles; 3rd joint reflexed on 2nd, curved, with 1 short proximal bristle on convex margin; tip with 6 stout teeth. Exopodite: bristles of joints 2–8 with natatory hairs and few widely separated, slender, ventral spines; 9th joint with 5 bristles with natatory hairs (2 short, 3 long); no basal spines present.

Mandible (Figure 145a,b): Coxale endite with small bristle near base of ventral branch; ventral branch with 11 oblique rows of hairs (proximal) and spines and tip with 2 stout teeth with several minute spines forming row between them; dorsal branch with 5 teeth projecting ventrally along ventral margin; main spine short with hairs along anterior margin; tip of dorsal branch with short spine with long hirsute bristle near its base (long bristle broken on illustrated endite, Figure 145b); margin between main spine and tip serrate; dorsal margin of dorsal branch serrate opposite distal teeth on ventral margin. Basale: endite with 6 pectinate end bristles, 5 triaenid bristles (one pair of spines very long), and 2 subequal, short, slender bristles; ventral margin of basale with 2 long spinous bristles, 2 triaenid bristles (one pair of spines very long), and 1 short spinous bristle; dorsal margin of basale with 5 slender proximal bristles, 1 short, slender, subterminal bristle, and 2 long, stout, terminal bristles; medial side with spines forming clusters on dorsal half. Exopodite with hirsute tip reaching distal end of 1st endopodite joint, with 2 subterminal ventral bristles. Endopodite: 1st joint with 5 ventral bristles (2 near middle of ventral margin, 3 terminal on ventral margin (bases on medial side)); ventral margin of 2nd joint with 4 long subterminal bristles; dorsal margin with numerous bristles; medial side with spines forming rows; end joint with 3 stout claws and 3 bristles; ventral and middle claws of end joint about same size, dorsal claw about 79 percent length of other claws.

Maxilla (Figure 145c,d): Epipodite long, slender; endite I with 4 long stout bristles and 2 minute bristles; endite II with 1 long stout bristle and 4 short slender bristles. Basale: ventral margin with 7 short slender bristles and 1 long, stout, terminal bristle with base of bristle on lateral side; dorsal margin with 4 or 5 proximal bristles (2–3 long, 1–3 short) and 6 or 7 distal bristles (2–3 long, 4–5 short); medial side hirsute, with 1 distal bristle. Endopodite: 1st joint hirsute, with 3 short dorsal bristles and 1 long hirsute beta-bristle terminally on ventral margin, end joint with 5 terminal bristles. Exopodite not observed.

Fifth Limb (Figure 144f): Dorsal margin of comb hirsute with bases of hairs on lateral side; lateral side with 1 short proximal bristle near dorsal margin, 1 stout, hirsute, exopodial bristle, and about 5 short slender bristles just posterior to stout bristle, and closer to ventral margin.

Sixth Limb (Figure 146a): Anterior margin with single distinct suture; margin above suture with medial bristles forming inner row and outer row; inner row with 10 short bristles with long hairs along proximal two-thirds; outer row with 14 longer hirsute bristles; margin below suture with 6 or 7 short, slender, hirsute bristles; about 13 stout spinous bristles present medial to lateral flap (some of these bristles could be considered to be on anterior part of ventral margin); ventral margin posterior to lateral flap with 8 spinous bristles; lateral flap with 2 fairly stout hirsute bristles followed by 6 short, slender, hirsute bristles; hirsute posteroventral margin tapering to rounded tip; distal end of posterior edge of narrow proximal part of limb with 1 short, hirsute, epipodial bristle; medial surface near ventral margin of limb with several minute bristles near ventral margin.

limb, lateral view; b, right lamella of furca and right Y-sclerite, lateral view.

Seventh Limb (Figure 144g): Each limb with about 31 bristles, about 14 on one side and 17 on other side, some segments with 2 bristles (1 on each side); each bristle with 1 to 7 bells but no marginal spines; terminus with opposing combs, each with total of 13–16 A- and B-teeth (see Kornicker, 1975b:13, fig. 8, for description of A- and B-teeth).

Furca (Figure 146b): Each lamella with 3 long stout claws followed by 7 short, slender, secondary claws; main claws with medial and lateral teeth forming rows along posterior margin; secondary teeth with slender teeth or spines along posterior and anterior margins; anterior margin of lamella with slender spines; long hairs present medially on lamellae at bases of main claws.

Rod-shaped Organ (Figure 145e): Elongate, broadening near middle, with rounded tip.

Eyes: Medial eye large, pigmented, bare (Figure 145e). Lateral eye about same size as medial eye, pigmented, with about 16 ommatidia (some embedded in pigment difficult to discern) (Figure 145e,f).

Posterior (Figure 145g): Hirsute; dorsal process fingerlike with spinous lobe at tip.

Upper Lip (Figure 145e): Consisting of hirsute lobe on each side of saddle; each lobe with about 3 anterior spines; a hirsute flap posterior to each lobe.

Brush-like Organ: Not observed.

Genitalia: Copulatory organ small.

Y-Sclerite (Figure 145h): Slightly sinusoidal.

Gill-like Structures: Well developed (tips of 2 gills shown in Figure 145g).

DESCRIPTION OF ADULT FEMALE (Figures 147–149, Plates 143–148).—Carapace similar to that of adult male except for being larger and having more rounded posterodorsal margin (Plates 143a,b, 146a).

Ornamentation: Surface with large fossae with minute papillae on bottom (Plates 143c,d, 144b,d, 146c); surface between papillae with minute processes having digitate tips (Plate 144d,e); surface of papillae within fossae pustulose (Plate 144e); surface of valve between fossae with papillae in some areas (Plate 143c) and with vesicular structure in other areas (Plate 144a,c).

Infold: Rostral infold with about 54 bristles forming row paralleling valve edge (Plates 145a–c, 146d); about 60 shorter bristles present between row of long bristles and anterior valve margin; list extending from point posterior to incisur to point near posterior end of ventral margin; about 46 small bristles present between list and anteroventral and ventral margins of valve (Plate 147a); posterior infold broad with bristles present in 3 areas (Plates 145d, 146d, 147b,c); outer area with about 22 long and 17 short bristles (Plates 145d, 146b,d, 147b,c,f, 148a–c); middle area with about 11 short bristles (Plate 147b–e); inner area with about 24 bristles of which about 10 are longer than others (Plates 147b,c, 148d,e).

Selvage: Similar to that of adult male (Plates 145c,d, 147a–c).

Size: USNM 157169, length 3.29 mm, height, 2.53 mm; USNM 157224, length 4.03 mm, height 2.96 mm; USNM 157232, length 3.00 mm, height 2.29 mm; USNM 157223, length 3.61 mm, height 2.59 mm.

First Antenna (Figure 147a,b): 1st joint with lateral and medial spines. 2nd joint with 5 dorsal bristles (4 proximal, 1 distal) and spines on medial side near ventral and distal margins. 3rd joint short, triangular, with 1 short ventral bristle and 3 dorsal bristles (1 near middle, 2 terminal). 4th joint short, with 5 bristles (1 dorsal, 4 ventral (1 very long, 3 short)). 5th joint long; sensory bristle with 4 or 5 short proximal filaments, 2 long subterminal filaments, and with tip of stem consisting of 2 long terminal filaments. 6th joint short with small medial bristle with spine at tip. 7th joint: a-claw smooth with weak rings distally; b-bristle about twice length of a-claw, with 5 marginal filaments excluding stem; c-bristle about one-fourth longer than b-bristle, with 7 marginal filaments excluding stem. 8th joint: d- and e-bristles bare with blunt tips, about same length as b-bristle; f-bristle curved dorsally near base, slightly shorter than c-bristle, with 8 marginal filaments excluding stem; g-bristle slightly longer than c-bristle, with 9 marginal filaments excluding stem.

Second Antenna (Figures 147c, 149a): Protopodite with medial bristle and long hairs along ventral margin. Endopodite 3-jointed: 1st joint weakly divided into proximal and distal parts on some specimens, with 5–21 proximal bristles; 2nd joint elongate, bare; suture between 2nd and 3rd joints indicated by slight restriction along margin; 3rd joint short with relatively short subterminal bristle. Exopodite: 1st joint with minute, recurved, medial bristle on distal margin; bristles of joints 2–8 with stout ventral spines and natatory hairs; 9th joint with 3 long ventral bristles with ventral spines and natatory hairs, and 2 shorter bristles with only natatory hairs; neither basal spines nor short spines forming rows along distal margins of joints present.

Mandible: Coxale endite (Figures 147d, 149b): small bristle present near base of ventral branch; ventral branch with spines and hairs forming about 10 oblique rows; hairs present on coxale proximal to ventral branch; tip of ventral branch with 2 stout teeth and 1 minute dorsal tooth (dorsal tooth with minute lateral spines); dorsal branch with 4–5 teeth along ventral margin; main spine with short hairs along anterior margin; tip of dorsal branch with short spine with long hirsute bristle near its base; margin between main spine and tip serrate; ventral margin of dorsal branch serrate opposite teeth on ventral margin. Basale: endite with 5 or 6 pectinate end bristles, 6–9 triaenid bristles (1 pair of spines very long), 3–5 subequal, short, slender bristles and 2 glandular processes; ventral margin of basale with 4 or 5 triaenid bristles (1 pair of spines very long), 1 long spinous bristle and 2 or 3 small bristles (the distal 1 or 2 of these with bases on lateral side); USNM 157244 with 1 or 2 short proximal bristles near ventral margin; dorsal margin of basale with 4–10 slender proximal bristles, 1–4 short, slender, subterminal bristles, and 2 long, stout, terminal bristles; medial side with spines forming rows on dorsal half. Exopodite similar to that on adult male. Endopodite: 1st joint with 6 ventral bristles; ventral margin of 2nd joint with 3 long subterminal bristles; dorsal margin with numerous bristles; medial side with spines forming rows and numerous cleaning bristles; end joint with 3 stout claws (dorsal claw about 70 percent of other claws) and 3 bristles (2 short, ventral, 1 long, lateral).

Maxilla (Figures 148a, 149c): Epipodite long, slender, hirsute ventrally and distally; endite I with 3 long stout bristles and 1 minute bristle; endite II with 2 long stout bristles and 1 short slender bristle; endite III with 1 long stout bristle, about 10 medium-to-long slender bristles, and 3 or 4 short slender bristles (USNM 157169 with fewer bristles on endite III; not all endites shown in Figure 148a). Basale: ventral margin with 5–7 slender bristles and 1 long, stout, spinous, terminal bristle; dorsal margin with 8–16 proximal bristles of various lengths and 6–12 distal bristles of various lengths; lateral side with 1 proximal bristle; medial side hirsute with 1 distal bristle. Exopodite minute with 3 bristles (1 fairly long, 2 short). Endopodite: 1st joint hirsute, with 1 or 2 short dorsal bristles, and 1 long hirsute beta-bristle terminally on ventral margin; end joint with 5 terminal bristles.

Fifth Limb (Figures 147e, 149d): Dorsal margin of comb hirsute with bases of hairs on lateral side, and 1–4 bristles at proximal end; lateral side with 1 short proximal bristle and 0 to 4 short distal bristles near dorsal margin, 1 stout, hirsute, epipodial bristle, 2 short bristles near middle posterior to base of stout epipodial bristle, and 5 or 6 short bristles near ventral margin posterior to stout epipodial bristle; ventral margin with hirsute bristles forming 2 rows except for about 6 distal bristles that form single row (bristles forming lateral row longer but fewer in number than bristles forming medial row).

Sixth Limb (Figure 149e): Anterior margin with single distinct suture; margin above suture with bristles forming 2 rows, inner medial row with about 12 bristles with long hairs proximally and short spines distally, outer row with about 30 longer, hirsute bristles (bristle near suture longer than others); margin below suture with single medial row of about 13 hirsute bristles; about 18 bristles present medial to lateral flap; ventral margin posterior to lateral flap with 8 or 9 spinous bristles; lateral flap with about 12 hirsute bristles (these decreasing in length posteriorly along edge of flap); hirsute posterior margin of skirt tapering to rounded tip with 0 or 1 short hirsute bristle; medial surface of skirt with numerous minute bristles near ventral and anterior margins; 1 or 2 short hirsute bristles present in place of epipodial appendage.

Seventh Limb: Each limb with 58–69 bristles, 24–32 on one side, 29–38 on the other, many segments with 2 bristles (1 on each side); some segments with 3 bristles (1 on one side, 2 on the other), each bristle with up to 8 bells; terminus with opposing combs, each with 16–22 teeth (Figure 149f).

Furca: Each lamella with 3 long stout claws followed by 6–10 slender secondary claws, otherwise similar to furca of adult male.

Rod-shaped Organ (Figures 148b, 149g): Elongate, broadening near middle, tapering to rounded tip, some specimens with suture proximal to middle.

Eyes (Figures 148b,c, 149g,h), Posterior of Body (Figure 148d); Y-Sclerite, Gill-like Structures: Similar to those of adult male, but exact number of ommatidia in lateral eye difficult to determine because of pigment.

Upper Lip (Figures 148b, 149i): Similar to that of adult male except anterior spines not observed.

Brush-like Organ: Not observed.

Number of Eggs in Marsupium: USNM 157232—19; USNM 157169—21, USNM 157224—19.

Protistans: Stalked protistans abundant along anterior margin of USNM 157224 (Plate 145a–c,e,f).

COMPARISONS.—Two species of Asteropterygion have been described from east Africa, both from the vicinity of Mombasa: A. skogsbergi (Poulsen, 1965) and A. spinosum (Poulsen, 1965). The carapace of A. thomassini differs from that of A. spinosum in not having short curved spines on its outer surface. The carapace of A. thomassini bears more ribs than that of A. skogsbergi. One species of Asteropterygion has been described from the Union of South Africa—A. nodulosum (Poulsen, 1965). That species has rimmed fossae touching each other and no central ribs in anterior half of valves.