Amboleberis antyx Kornicker 1981

Amboleberis antyx

ENTYMOLOGY.—The specific name from the Greek antyx (rim, edge, frame) in reference to the vertical ridge posterior to the incisur on the valves of the species.

HOLOTYPE.—USNM 157625, juvenile female (instar IV?), on slides and in alcohol.

TYPE-LOCALITY.—Station BT–230, Madagascar.

PARATYPES.—Madagascar: USNM 157728, 1 adult male, sta BT-172; USNM 157736, 157738, 3 specimens, sta BT-222; USNM 157726, 1 juvenile male, sta BT-230.

DISTRIBUTION.—Madagascar at depths of 21–29 m (Figure 39).

DESCRIPTION OF JUVENILE FEMALE (Instar IV?) (Figures 67, 68, Plates 47–49).—Carapace oval in lateral view (Figure 67a, Plate 47a), with deep incisur near middle of anterior margin (Plate 47a,b); valve widest just posterior to middle (Plate 47c).

Ornamentation: Anterior margin without scalloped border; vertical ridge present posterior to incisur and intersecting ventral margin of valve (Plate 47a,b); surface of valve with abundant minute pits with low narrow rims (Plate 48 d,e); bristles present emerging from open pores without rims (Plate 47d–f), with single narrow rim (Plate 48a), or concentric rims (Plate 48b,c); pores with single rim and without bristles also present (Plates 47f, 48d).

Infold: Ventral and posterior segments of infold broader than usual in members of genus, but with similar types of bristles (Plate 49).

Concretions: Abundant in each valve of holotype (Plate 47a–c); concretions not penetrating outer layer of shell (Plate 48f).

Size: USNM 157625, length 1.85 mm, height 1.63 mm.

First Antenna (Figure 67b); 1st joint with long hairs along ventral margin and on medial surface near ventral margin, and short, slender, lateral spines near distal dorsal margin. 2nd joint: hairs along ventral and dorsal margins and on medial and lateral surfaces; dorsal margin with 2 bristles; lateral surface with 1 distal bristle. 3rd joint: short ventral margin with 1 small bristle; long dorsal margin with 6 bristles; lateral surface with hairs near dorsal margin. 4th joint: short dorsal margin with 1 long terminal bristle; long ventral margin with 3 terminal bristles (1 long, 2 short); medial side with long hairs near dorsal margin. 5th joint: medial side with long hairs near dorsal margin; sensory bristle with 5 short proximal filaments and 7 long terminal filaments. 6th joint: well-defined, with 1 long medial bristle. 7th joint: a-bristle clawlike, with about 16 stout teeth along proximal half of dorsal margin; b-bristle about one-third longer than a-bristle, with about 6 marginal filaments excluding tip; c-bristle reaching well past tip of sensory bristle of 5th joint, with about 9 marginal filaments excluding tip. 8th joint: d- and e-bristles bare with blunt tips reaching just past tip of sensory bristle; f-bristle bent dorsally, distal part broken off on specimen examined, but with 4 or 5 ventral filaments on remaining part; g-bristle broken off on specimen.

Second Antenna (Figure 67c-e): Protopodite with few hairs along ventral margin and short, distal, medial bristle. Endopodite: proximal and distal parts of 1st joint each with 4 or 5 short bristles; 2nd joint bare; 3rd joint with long terminal bristle. Exopodite: 1st joint with few slender spines along dorsal margin and minute, distal, medial spine; 2nd joint with spinous bristle just reaching 9th joint; minute teeth forming medial row at base of bristle of 2nd joint; bristles of joints 3–8 with stout ventral spines and natatory hairs; 9th joint with stout lateral spine and 4 bristles (2 long with ventral spines and natatory hairs, 2 short with only natatory hairs); joints 2–8 with stout basal spines and minute spines forming row along distal margin.

Mandible (Figure 68a): Coxale endite: slender bristle present at base of ventral branch; ventral branch with spines forming about 5 oblique rows; tip with 3 minute teeth (dorsal of these blunt); ventral margin of dorsal branch with 6 processes proximal to small main spine; tip terminating in long bristle; posterior margin of main spine and margin between main spine and tip of dorsal branch with minute spines. Basale endite: tip with about 5 end-type bristles; ventral margin of endite with about 8 triaenid bristles (paired teeth decreasing in length distally along bristle); 4 dwarf bristles present (distal of these longer than others). Basale: ventral margin with 4 or 5 triaenid bristles of same type as on endite and 2 longer, distal, spinous bristles; medial side hirsute, with 1 minute proximal bristle near ventral margin; lateral side hirsute, with 3 distal bristles near ventral margin; dorsal margin with 9–11 short and medium bristles and 2 longer, spinous, distal bristles. Exopodite: hirsute tip reaching just past distal end of 1st endopodial joint, with 2 spinous ventral bristles (distal of these shorter than other). Endopodite: 1st joint with 6 ventral bristles (1 of these minute); ventral margin of 2nd joint with bristles forming 2 distal groups (proximal of these with 3 bristles, other with 2); dorsal margin and medial surface near dorsal margin with numerous bristles (about 3 of the cleaning bristles with stout marginal spines); medial surface with few spines forming distal rows; end joint with 3 claws, 1 long lateral bristle, and 2 ventral bristles.

Maxilla (Figure 67f): Epipodite with few faint spines and tip reaching about two-thirds length of dorsal margin of basale. Endite I with 3 or 4 long bristles; endite II with 1 short and 2 long bristles; endite III with 2 long bristles; 5 short bristles present just distal to bases of bristles of endite III. Basale: Dorsal margin with 3 short proximal bristles with bases on medial surface and 4 distal bristles; ventral margin with 10 short proximal bristles, 3 long distal bristles, and 1 long, spinous, terminal bristle; lateral surface with 1 short proximal bristle. Medial surface with 3 short distal bristles. Exopodite: minute lobe with 1 long and 2 short bristles. Endopodite: 1st joint with 3 short bristles on anterior margin and 1 long spinous beta-bristle; end joint with 5 or 6 bristles.

Fifth Limb (Figure 67g): Lateral surface of comb with stout spinous exopodial bristle reaching past end of comb, 4 minute bristles just proximal to base of stout bristle, 8 small bristles near margin ventral to base of stout bristle, and 2 short proximal and 2 short distal bristles near ventral margin.

Sixth Limb (Figure 68b): Anterior margin with 2 distinct sutures; margin dorsal to upper suture with bristles forming 3 rows containing 9 bristles in inner row, 8 bristles in middle row, and 12 shorter and more slender bristles in outer row; margin between sutures with 2 bristles in inner row, 2 in middle row (ventral of these quite long), and 3 bristles in outer row; margin ventral to lower suture with 5 short slender bristles forming single row (continuance of outer row present dorsal to suture); lateral flap with 2 slender spinous bristles; ventral margin of skirt with numerous bristles; posterior end of skirt with 4 hirsute bristles; 1 short hirsute bristle present in place of epipodial appendage.

Seventh Limb: Each limb with 39 or 40 bristles, 18 to 21 on each side; many joints with 2 bristles, 1 on each side; each bristle with up to 5 bells; many bristles strongly tapering distally (a juvenile character); terminus with opposing combs, each with about 19 spinous teeth of various types (Figure 67h).

Furca (Figures 67i, 68e): Each lamella with 4 stout claws, 1 short bristle between claws 3 and 4, but closer to claw 4, and 4 bristles following claw 4; space between claw 4 and following bristle wider on left lamella than on right lamella, main claws with stout teeth separated by smaller teeth, and with small teeth distally.

Rod-shaped Organ (Figure 68d): Elongate, broadening near middle, than tapering to rounded tip.

Eyes: Medial eye bare, without pigment (Figure 68d). Lateral eye about same size as medial eye, without pigment, with about 28 ommatidia (Figure 68c).

Upper Lip (Figure 68d): Consisting of 2 hirsute lobes with medial saddle bearing few anterior hairlike spines; hirsute lateral flap on each side of mouth.

Posterior (Figure 68e): Hirsute, but without dorsal process.

Y-Sclerite (Figure 68e): Normal for genus.

DESCRIPTION OF ADULT MALE (Figures 69, 70, Plates 50–51).—Carapace oval in lateral view (Figure 69a); hairs present near posterior end of each valve (Figure 69a, Plate 50a).

Ornamentation: Anterior margin without scalloped border (Plate 50c); vertical ridge present posterior to incisur and intersecting ventral margin of valve (Figure 69a, Plate 50a,b); surface of valve with abundant minute pores (Plate 50d); bristles present emerging from closed pores (Plate 50d, 51a), and from open pores without rims, with single rim, and with concentric rims (Plate 50d–f); pores without bristles also present (Plate 50d,f). Surface appearing matted where outer layer of shell missing (Plate 51b).

Infold (Plate 51c,e,f): Similar to that of female.

Central Adductor Muscle Attachments (Figure 69a, Plate 51d): Typical for genus.

Size: USNM 157728, length 2.00 mm, height 1.60 mm.

First Antenna (Figure 69b–d): 1st joint bare. 2nd joint: hairs along ventral margin, on medial side near ventral margin, and on medial side near middle of distal margin; dorsal margin with 1 bare distal bristle (an empty socket near middle of margin suggests that another bristle may have broken off); lateral side bare. 3rd joint: short ventral margin with 1 small bristle; long dorsal margin with 6 bare bristles; lateral side with hairs near dorsal margin. 4th joint: short dorsal margin with 1 long, bare, terminal bristle; long ventral margin with 4 bristles (1 long, 3 very short). 5th joint with stout filamentous sensory bristle (distal end broken off on both limbs of USNM 157778). 6th joint with long, bare, medial bristle on distal end near dorsal margin. 7th joint: a-bristle clawlike, with about 11 proximal teeth along dorsal margin (not all shown in Figure 69b); b-bristle about one and one-half times longer than a-bristle, with 8 marginal filaments including tip; c-bristle about 3 times length of b-bristle and almost 5 times length of a-bristle, with about 17 filaments including tip (proximal filaments with widened proximal section, Figure 69d). 8th joint: d- and e-bristles bare with blunt tips, more than twice length of a-bristle; f-bristle about 3-times length of a-bristle and almost twice length of b-bristle, with about 13 filaments including tip (proximal filaments with widened proximal section, similar to those of c-bristle, but bristle only about two-thirds length of c-bristle); g-bristle same length as f-bristle, with about 16 filaments.

Second Antenna: Protopodite with short, distal, medial bristle; no ventral hairs observed. Endopodite (Figure 69e): proximal part of elongate 1st joint with 4 minute bristles, distal part with 3 minute bristles; elongate 2nd joint with 7 or 8 short bristles; elongate 3rd joint reflexed on 2nd, with 1 long proximal bristle, 2 small terminal bristles, and ridges along inner margin. Exopodite: 1st joint with few slender spines along dorsal margin and minute, straight, distal, medial spine; bristle of 2nd joint more than twice length of combined length of joints 2–9, with ventral spines and natatory hairs; minute teeth forming medial row at base of bristle of 2nd joint; bristles of joints 3–8 with stout ventral spines and natatory hairs; 9th joint with stout lateral spine and 5 bristles (2 long with ventral spines and natatory hairs, 1 medium and 2 short with only natatory hairs); joints 2–8 with stout basal spines and minute spines forming row along distal margin.

Mandible: Coxale endite: ventral margin of dorsal branch with 8 processes proximal to short main spine (Figure 69f), otherwise similar to that of female. Basale endite similar to that of female. Basale: ventral margin with 5 triaenid bristles (bristles similar to those of female) and 3 longer, distal, spinous bristles; medial side without hairs, but with 2 minute bristles near ventral margin; lateral side with 3 small distal bristles near ventral margin; dorsal margin with 10 short proximal bristles and 2 long, spinous, distal bristles. Exopodite similar to that of female. Endopodite: 1st joint similar to that of female; ventral margin of 2nd joint with bristles forming 2 distal groups (proximal of these with 5 bristles, distal with 2); remaining part of 2nd joint as well as 3rd joint similar to those of female.

Maxilla (Figure 70a,b): Endites I and II each with 1 short and 3 long bristles; endite III with 3 long bristles; 5 medial bristles present just distal to endites. Basale: dorsal margin with 1 short bristle with base on medial surface and 3 distal bristles; ventral margin with 12 or 13 short proximal bristles, 2 long, spinous, distal bristles (proximal of these extremely stout) and 1 long, spinous, terminal bristle; medial surface with 4 distal bristles (ventral of these long, others short). Exopodite: minute lobe with 1 long and 2 short bristles. Endopodite: 1st joint with 3 short bristles on anterior margin and 1 long beta-bristle; end joint with 5 or 6 bristles.

Fifth Limb (Figure 70c): Lateral surface with stout, spinous, exopodial bristle and 3 minute bristles proximal to base of stout bristle; only 3 of the 12 small lateral bristles observed near ventral margin of comb of female also observed on male, but bristles possibly broken off on male; dorsal margin with 4 minute proximal bristles, and hairs along distal end; dorsal margin without processes.

Sixth Limb: Similar to that of female except 1 of the limbs without epipodial bristle, other with 1 bristle as on female.

Seventh Limb: Similar to that of female, but bristles not counted.

Furca: Similar to that of female, except some of bristles following claw 4 broken off, probably about 6 originally present.

Rod-shaped Organ (Figure 70d): Similar to that of female.

Eyes: Medial eye similar to that of female except with brown pigment (Figure 70d). Lateral eye about same size as medial eye, with black pigment and about 33 ommatidia forming 5 rows (Figure 69g).

Upper Lip (Figure 69h), Posterior of Body, Y-Sclerite: Similar to those of Female.

COMPARISONS.—The only other species of Amboleberis having a verticle rib posterior to the incisur is A. americana. That species differs from A. antyx in having nodes along the posterior margin of the 5th joint of the 1st antenna and in not having teeth on the a-bristle of the 1st antenna.

ASTEROPTERONINAE, new subfamily

COMPOSITION.—This new subfamily is comprised of 7 genera: Asteropella Poulsen, 1965; Microasteropteron Poulsen, 1965; Asteropteron Skogsberg, 1920; Actinoseta Kornicker, 1958; Asteropterygion, new genus; Pteromeniscus, new genus; Omegasterope, new genus.

DISTRIBUTION (Figure 1).—From about 42°S to about 42°N. Pteromeniscus intesi, new species, collected at 270–699 m appears to be a bathyal species; except for 1 sample containing Asteropterygion setiferum collected at 1100 m off Mauritania, remaining species of Asteropteroninae have not been collected below about 100 m.

DIAGNOSIS.—Carapaces generally oval in lateral view, but some with posterodorsal projections; incisur generally forming right angle between ventral margin of rostrum and anterior margin of valve below rostrum, not forming the deep incisur of the type present in the Cylindroleberidinae and Cyclasteropinae; with the exception of some species of Actinoseta, surface with ribs and large processes; surface details usually more complex than found in other subfamilies of the Cylindroleberididae; bristle pores with concentric rims present on many species of Cylindroleberidinae and Cyclasteropinae not present; dorsal margin of each valve of Actinoseta with groove and spur dentition; carapace of adult male generally smaller than that of adult female, but not more elongate, and without vertical row of hairs near posterior edge; central adductor muscle attachments generally consisting of many discrete, individual, ovoid scars forming cluster.

First Antenna: Dorsal margin of 5th joint without teeth or nodes; sensory bristle of 5th joint of female variable (see Figure 9 for examples), generally with fewer filaments than on either the sensory bristle of Cylindroleberidinae or Cyclasteropinae; a-bristle of 7th joint either bristle-like or clawlike; c- and f-bristles of adult male not extra long as on most species of Cylindroleberidinae and Cyclasteropinae; development of d- and e-bristles varies considerably among genera and species (see Figure 10 for examples).

Second Antenna: Second exopodial joint of adult male not extra long as in Cylindroleberidinae and Cyclasteropinae; exopodial joints without basal spines (except Asteropterygion hirsutum); 9th joint with 1–5 (rarely 6) bristles; exopodial bristles of both sexes generally with spines as well as hairs. Endopodite of female 1-jointed in Microasteropteron, 3-jointed in other genera but joints often fused; endopodial joints variable in relative lengths and armature of hairs and bristles among genera (see Figure 12 for examples). Endopodite of adult male 3-jointed; 3rd joint reflexed on 2nd and varying in length among different genera (see Figure 13 for examples).

Maxilla: Exopodite variable: absent, consisting of 1 or 2 bristles, or small lobe with up to 3 bristles. Endopodite with 3–7 bristles on end joint.

Fifth Limb: Comb of adult males without processes such as those on adult males of Cyclasteropinae; dorsal margins of combs generally hirsute, and with a few minute bristles on some species; lateral side of comb with 1–2 long bristles and several short bristles; position of the more slender of the 2 long bristles proximally located on some genera.

Sixth Limb: Limb of Microasteropteron resembling those of the Cylindroleberidinae; limbs of other taxa resembling more those of Cyclasteropinae; limbs either without, or with 1–4 epipodial bristles; anterior margin of trunk with numerous bristles (except Microasteropteron, which has 2–4 bristles on anterior margin of trunk); ventral margin of skirt with numerous bristles; posterior tip of skirt without bristles, or with 1–5 bristles (see Figure 14 for examples).

Seventh Limb: Terminus with opposing combs or with teeth not distinctly separated into opposing combs; type of comb varies among genera (see Figure 15 for examples).

Furca: Distribution of main and secondary claws varies among genera, but no species with bristles or secondary claws between main claws (see Figure 16 for examples).

Upper Lip: Spineation of lobes varies: no spines, several small spines, 1 very long spine (see Figure 17 for examples).

Posterior of Body: Fingerlike dorsal process well developed on all members.

Gills: Gills generally well developed, but fairly small on some species.

COMPARISONS.—The new subfamily Asteropteroninae differs from the Cylindroleberidinae and Cyclasteropinae in many ways; for example, the carapace of most genera of Asteropteroninae have ribs, ridges, and processes absent on carapaces of other subfamilies. Some species of Actinoseta, which have fairly smooth carapaces, are exceptions; members of Actinoseta have spur and groove dentition along the dorsal margin not present on any members of other subfamilies. The incisurs on carapaces of most Asteropteroninae differ from those in the other families in being formed by a right angle, or a fairly open acute angle, between the ventral margin of the rostrum and the anterior margin of the valve below the rostrum; on the carapaces of the other subfamilies, the incisur forms a slit extending into the anterior margin just below the rostrum. The central adductor muscle attachments of Asteropteroninae differ from those of the Cyclasteropinae in consisting of small ovoid scars without a spiral arrangement. The microstructures of the surface of members of the Asteropteroninae are extremely variable, and generally more complex than the other subfamilies, especially that of the Cylindroleberidinae. The sensory bristle on the 5th joint of the adult female of members of Asteropteroninae are variable (see Figure 9 for examples), but differ considerably from members of other subfamilies. The 2nd antennae of members of the Asteropteroninae differ from those of the Cyclasteropinae in not having basal spines on exopodial joints (except for Asteropterygion hirsutum). For other differences see discussion of Cypridinacea (p. 42).