Asteropterygion peterseni Kornicker 1981

Asteropterygion peterseni

ETYMOLOGY.—The species is named for Hans Petersen, Institute of Zoology, University of Hamburg.

HOLOTYPE.—USNM 157702, ovigerous female in alcohol.

TYPE-LOCALITY.—Off Tanzania, in vicinity of Kunduchi, exact water depth unknown, between 0–25 m, sample probably collected from about 0.5 m; collected 17 Jan 1974.

PARATYPE.—USNM 157701, ovigerous female on slides and in alcohol, from same sample as holotype; USNM 157716, 1 specimen, sta 107, from off Tanzania; USNM 157717, 1 specimen, sta 54, from off Tanzania.

DISTRIBUTION (Figure 131).—Continental shelf of Tanzania, probable depth 0–25 m.

DESCRIPTION OF ADULT FEMALE (Figures 160–163, Plates 171–175).—Each valve with 2 prominent horizontal ribs; upper of these linear, other slightly concave dorsally (Plate 171a–d). A 3rd narrow rib paralleling dorsal margin. The 2 prominent ribs terminating posteriorly in small backward-pointing process. A long backward-pointing process present at midheight of valve between the 2 prominent horizontal ribs; posterior margin of valve with small caudal process, and a posterior process just ventral to posterior process of upper prominent horizontal rib; tip of rostrum pointed and extending past valve edge; area of valve ventral to rostrum depressed and with anterior process extending past edge of valve.

Ornamentation: Surface with numerous shallow fossae containing small pustules (Plates 171e, 172a,d); Surface between fossae with minute fenestella and pustules (Plate 172b,c).

Infold (Plates 172e,f, 173a–d): Normal for genus.

Size: USNM 157701, length 2.69 mm, height 2.04 mm; USNM 157702, length 2.76 mm, height 2.01 mm.

First Antenna (Figure 160a): 1st joint with long medial and lateral hairs forming rows near ventral margin. 2nd joint: ventral margin with long hairs; medial side with hairs forming rows near ventral margin and along distal margin; dorsal margin with proximal hairs and 5 bristles (4 proximal, 1 distal). 3rd joint: short ventral margin with 1 short bristle; long dorsal margin with 1 proximal and 2 terminal bristles. 4th joint: short dorsal margin with 1 terminal bristle; long ventral margin with 4 small terminal bristles. 5th joint: sensory bristle with 5 short proximal filaments, 2 long, distal, marginal filaments, and bifurcating tip. 6th joint with small medial bristle. 7th joint: a-bristle about same length as dorsal margin of joints 4–8; distal end ringed and drawn out to pointed tip, bristle-like; b-bristle reaching past tip of a-bristle, with 4 marginal filaments and bifurcate tip; c-bristle slightly longer than sensory bristle of 5th joint, with 9 marginal filaments and bifurcate tip. 8th joint: d- and e-bristle about same length as b-bristle, bare with blunt tips; f-bristle slightly bent dorsally in proximal part, slightly longer than b-bristle, with 7 ventral filaments and bifurcate tip; g-bristle slightly longer than c-bristle, with 8 marginal filaments and bifurcate tip.

Second Antenna (Figure 160b): Protopodite with hairs along ventral and dorsal margins and on medial surface near ventral margin, and medial bristle about same length as longest bristle on 1st endopodial joint. Endopodite 3-jointed: 1st joint with 15 bristles; 2nd joint bare, weakly delimited from 3rd joint; 3rd joint with long subterminal bristle and very faint, minute, terminal spine. Exopodite: 1st joint with minute medial spine on distal margin; bristle of 2nd joint very long, with natatory hairs and slender ventral spines; bristles of joints 3–8 with natatory hairs and slender ventral spines; 9th joint with 5 bristles (3 with natatory hairs and slender ventral spines, 2 with only natatory hairs); joints 2–8 with long hairs along inner distal margin; basal spines absent.

Mandible (Figure 161): Coxale endite: small medial bristle present near base of ventral branch; ventral branch with proximal hairs, spines forming about 8 oblique rows, and tip with 3 minute teeth; ventral margin of dorsal branch with 5 nodes and small main spine; tip with small pointed process posterior to base of long dorsal bristle; margin between main spine and tip serrate; dorsal margin of branch serrate. Basale endite: tip with 6 end-type bristles; ventral margin with 7 triaenid bristles having 1 pair of teeth much longer than others; 6 dwarf bristles present (distal of these about three times length of others). Basale: ventral margin with 2 proximal triaenid bristles, 1 long, spinous, distal bristle, and 4 small bristles; dorsal margin with 4–5 short proximal bristles and 5 distal bristles (3 short, 2 very long); medial surface with long hairs near dorsal margin. Exopodite reaching distal margin of 1st endopodial joint, hirsute, with 2 ventral bristles (exopodite of right limb of 157701 with proximal bristle shorter than distal bristle, but distal bristle shorter than proximal bristle on left limb). Endopodite: 1st joint with 6 ventral bristles; ventral margin of 2nd joint with bristles forming 2 groups, each with 2 bristles; dorsal margin and medial surface (near dorsal margin) of 2nd joint with numerous bristles (a few of the cleaning bristles with broad marginal spines not shown in illustrated limb); medial surface with spines forming rows; end joint with 3 claws (dorsal of these shorter than others and with ventral spines), 1 long lateral bristle, and 2 short ventral bristles.

Maxilla (Figure 162): Epipodial appendage hirsute, tip reaching distal bristles on dorsal margin of basale. Endites I and II each with 2 long stout bristles and 1 minute bristle; endite III with 1 or 2 long stout bristles and about 10 shorter bristles (some of these may be on basale). Basale: dorsal margin spinous, with 13 proximal bristles with bases on medial surface, and 11 distal bristles (some of these with bases on medial surface); ventral margin with 5–7 short bristles and 1 long terminal bristle (base of latter on lateral surface); medial surface with 1 distal bristle near ventral margin. Exopodite consisting of 1 long and 2 shorter bristles. Endopodite: 1st joint spinous, with 4 anterior bristles and 1 long spinous beta-bristle; end joint with 5 bristles.

Fifth Limb (Figure 163a): Dorsal margin of comb hirsute near middle and distally, with 5 proximal and 3 distal short bristles; lateral surface with long, stout, spinous bristle almost reaching end of comb, about 7 short bristles proximal and ventral to base of stout bristle, and 2 short distal bristles with bases almost on ventral margin.

Sixth Limb (Figure 163b): Anterior margin with distinct suture separating trunk from skirt and more proximal faint suture; anterior margin of trunk dorsal to upper suture with spinous bristles forming 2 rows (9 bristles in inner row, 16 longer bristles in outer row); margin between sutures with 1 bristle in inner row and 4 bristles in outer row; anterior margin of skirt ventral to lower suture with 3 bristles; lateral flap with about 10 slender spinous bristles; anterior end and ventral margin of skirt with about 15 spinous bristles; posterior end of skirt hirsute, without bristles; medial surface of skirt with many minute bristles; a single spinous bristle in place of epipodial appendage.

Seventh Limb (Figure 16c): Each limb with 51–57 bristles, 25–32 on each side; each bristle with up to 6 bells; some joints with up to 4 bristles, 2 on each side; terminus with opposing combs, each with about 18 spinous teeth of various types.

Furca (Figure 160d): Each lamella with 3 main claws followed by 8 unringed secondary claws; main claws with anterior hairs and posterior teeth consisting of 2 rows of stout teeth separated by several smaller teeth; secondary claws with teeth along posterior margin and hairs and few teeth along anterior margin; anterior margin of lamella with short hairs; long hairs present on medial side of lamellae near bases of main claws, and along edge of lamella following main claws.

Rod-shaped Organ (Figure 160e, Plates 173e,f, 174a,b): Elongate with suture proximal to widened middle part; tip narrow, rounded.

Eyes: Medial eye bare, with black pigment (Figure 160e, Plate 173e,f). Lateral eye about same size as medial eye, with black pigment and about 17 ommatidia (Figure 160f).

Upper Lip (Figure 160g,h, Plates 173e, 174a,c, 175): Each lobe hirsute, with anterior spines; middle saddle with anterior spines; hirsute lateral flap present on each side of mouth.

Posterior of Body (Figure 163d): Posterior hirsute, with fingerlike dorsum with long hairs at tip.

Y-Sclerite (Figure 160i): Normal for genus.

Eggs: USNM 157701 with 20 eggs in marsupium; USNM 157702 with 10 eggs in marsupium (Figure 163c).

COMPARISONS.—The carapace of the new species, A. peterseni, is similar to that of Asteropterygion skogsbergi (Poulsen, 1965). Based on the description of the latter species by Poulsen (1965:206), differences between the 2 species are as follows:

A. skogsbergi

A. peterseni

a-bristle of 1st antenna short and clawlike (-), long and bristle-like distally (+)

− +

Coxale endite of mandible without basal bristle (-), with basal bristle (+)

− +

Upper lip without spines on middle part (-), with spines on middle part (+)

− +

Posterior of body with strongly tapering process very wide at middle (-), with cylindrical process (+).

− +

Pteromeniscus, new genus

TYPE SPECIES.—Pteromeniscus intesi, new species, herein, monotypic.

ETYMOLOGY.—Generic name derived from the Greek ptero (wing or fin) plus meniskos (crescent) in reference to the crescent-shaped alar projection on the valves of the type-species. Gender masculine.

DISTRIBUTION.—Continental slope of Mauritania at depths of 270–699 m (Figure 125).

DIAGNOSIS.—Carapace with broad flange parallel to, and just within, valve margins, except in vicinity of minute incisur, where it is absent; crescentlike lateral ridge with midpart ventral to central adductor muscle attachment area.

First Antenna: Sensory bristle of female (known only from instar III) with few, short, proximal filaments, 1 long filament near middle reaching tip of stem, and 3 shorter terminal filaments including stem. Medial bristle of 6th joint fairly long. Eighth joint: d- and e-bristles well developed but not longer than a-bristle of 7th joint.

Second Antenna: Endopodite 3-jointed: 1st and 2nd joints short, bare; 3rd joint elongate, hirsute, with long terminal bristle.

Mandible: Ventral margin of basale only with triaenid bristles.

Maxilla: End joint of endopodite with 3 bristles.

Fifth Limb: Lateral side of comb with 2 long and several short bristles.

Sixth Limb: Without epipodial bristle. Posterior end of skirt with 1 short bristle on type-species.

Seventh Limb: Terminus with recurved teeth of similar type.

Furca: Each lamella of type-species with 7 primary claws: claws 1 and 2 similar in length, remaining claws decreasing in length proximally along lamella.

Lateral Eye: Absent on type species.

Upper Lip: Each lobe of lip of type-species with stout anterior process.

Posterior of Body: With hirsute thumblike process.

COMPARISONS.—The carapace of Pteromeniscus differs from that of Asteropella in having a crescentic rib ventral to the central adductor muscle attachment area rather than a linear rib going through, or just dorsal to, the attachment area. The 1st antenna of female Pteromeniscus (known only from instar III) differs from the 1st antennae of species of Asteropella in having a sensory bristle with a long filament near the middle, in having a bristlelike rather than a clawlike a-bristle, and in having a d-bristle almost the same length as the e-bristle (the latter is rarely present in Asteropella). The claws on the caudal furca of Pteromeniscus are not as sharply separated into primary and secondary claws as those on the caudal furca of species of Asteropella, nor does each lamella of the furca of Pteromeniscus bear a long, laterally placed, proximal bristle such as those present on many species of Asteropella. Claws 1 and 2 are closer together than these claws on the furca of Asteropella. The endopodite of the 2nd antenna of Pteromeniscus is quite small relative to the exopodite when compared with the endopodite and exopodite of species of Asteropella.

The 1st antenna of female Pteromeniscus differs from that of Asteropteron in having a sensory bristle with a long filament near the middle and in having a well-developed d-bristle. The endopodite of the 2nd antenna of female Pteromeniscus is much longer relative to the exopodite when compared with those of Asteropteron. The general appearance of the peripheral ridge on the carapace of Pteromeniscus resembles that on the carapace of species of Asteropella rather than that on the carapace of species of Asteropteron. Claws 1 and 2 of the furca are closer together on Pteromeniscus than they are on Asteropteron. The carapace of Pteromeniscus does not resemble those of Asteropterygion. Claws 1 and 2 of the furca are closer together on Pteromeniscus than they are on Asteropterygion.