Tetraleberis tanzania Kornicker 1981

Tetraleberis tanzania

ETYMOLOGY.—Specific name from the locality of the holotype.

HOLOTYPE.—USNM 157414, 1 female (adult or A-1 instar), on slides and in alcohol.

TYPE–LOCALITY.—Station 80, off Tanzania.

ALLOTYPE.—USNM 157415, 1 adult male from off Tanzania, station not designated, off East Kunduchi.

NON-TYPES.—USNM 157627, 157628, 2 juvenile females (probably instar II) from off Somalia, Indian Ocean, sta 9-446. Madagascar: USNM 157740, 1 juvenile, sta BT-622; USNM 157721, 1 adult male, sta BT-623; USNM 157748, 2 juveniles, BT-740; USNM 157730, 1 late juvenile, BT-822D.

DISTRIBUTION (Figure 44).—Somalia, Indian Ocean, at depth of about 65 m; Madagascar at depths of 7–12 m; Tanzania at unknown depth but not deeper than 25 m.

DESCRIPTION OF FEMALE (Probably Adult or A1 Instar) (Figures 53–55a; Plates 37–40).—Carapace oval in lateral view with deep incisur at middle of anterior margin (Figure 53a; Plate 37a,c,d).

Ornamentation: Fossae and ridges absent. Anterodorsal and anteroventral margin with unscalloped ridge (Plate 37d-f). Bristles with pore near base emerging from open pores without rims (Plate 38c) and open pores with 6–8 more-or-less concentric rims (Plate 38a,b,d,f); bristles from rimmed pores longer than those from unrimmed pores; minute simple pores sparsely distributed on valve surface (Plate 38a,d,e); abundant minute punctae on valve's surface visible only at very high magnification (Plate 38e); minute papillae observed in some areas (not illustrated); anterior, ventral, and posterior margins with long bristles forming row just lateral to selvage (Plate 37).

Infold: Anterodorsal, anteroventral, and ventral infolds with numerous bristles (Plate 39a-c); posterodorsal list with long and short tubular bristles (Plates 39d-f, 40); tubular bristles with small proximal flap with digitate distal edge (Plate 40a,b), and with digitate open tips (Plate 40c,e,f); short bristles, with fingerlike tips, forming row just proximal to tubular bristles (Plate 40c,d); a few minute tubular bristles present distal to the row of long and short tubular bristles (Plate 39e,f); bristles of various lengths forming row between posterior list and valve edge (Plate 39d-f). Anteroventral list with lamellar prolongation (Plate 39c).

Selvage: Lamellar prolongation of selvage along anterodorsal margin with marginal fringe (Plate 37f).

Central Adductor Muscle Attachments: Normal for genus.

Size: USNM 157414, length 3.2 mm, height 2.8 mm.

First Antenna (Figure 53b,c): 1st joint with long lateral and medial hairs near ventral margin, and minute spines forming medial row near distal margin. 2nd joint: long medial and lateral hairs near ventral margin; dorsal margin with 5 bristles; lateral side with 5 or 6 distal bristles. 3rd joint: short ventral margin with small bristle; long dorsal margin with 14 spinous bristles; lateral side with hairs near dorsal margin. 4th joint: short dorsal margin with 1 long spinous bristle; long ventral margin with 5 terminal bristles (1 long, 4 short). 5th joint: dorsal margin with stout sclerotized tooth proximal to middle; lateral and medial sides with long hairs near dorsal margin distal to protuberance; sensory bristle of 5th joint with 7 short marginal filaments and 9 longer terminal filaments (the proximal terminal filament much shorter than others). 6th joint with spinous medial bristle extending past tip of a-bristle of 7th joint: 7th joint: a-bristle clawlike, bare, equal in length to combined lengths of joints 5–8; b-bristle stout, about one and one-half times longer than a-claw, with about 10 filaments including 4 at tip; c-bristle longer than sensory bristle of 5th joint, with 13 marginal filaments (excluding tip). 8th joint: d- and e-bristles bare, with blunt tips reaching tip of sensory bristle; f-bristle bent dorsally, with 11 ventral marginal filaments; g-bristile about same length as c-bristle, with 13 marginal filaments (excluding tip).

Second Antenna (Figure 53d-g): Protopodite with long hairs along ventral margin and on medial surface near ventral margin, and 1 short, bare, distal, medial bristle. Endopodite: 1st joint divided into proximal part with 3 small bristles, and distal part with 6 short bristles; 2nd joint bare, with well-defined sutures separating it from 1st and 3rd joints; 3rd joint with long terminal bristle with blunt tip. Exopodite: 1st joint with spines along dorsal margin and on medial and lateral surfaces near dorsal margin, and minute, straight, terminal, medial spine; bristle of 2nd joint about five-sixth length of dorsal margin of 1st joint, with abundant short hairs (these could be called slender spines but are not similar to stout spines on bristles of other exopodial joints); bristles of joints 3–8 with natatory hairs and stout proximal ventral spines; 9th joint with 5 bristles (3 with proximal ventral spines and natatory hairs, 2 with only natatory hairs); joints 2–8 with large basal spines; 9th joint with lateral spine equal to length of joint; joints 2–8 with minute spines forming row along distal margin.

Mandible (Figure 53h): Coxale endite broken off both limbs of specimen examined; small bristle present near base of ventral branch. Basale endite: tip of endite with 4 or 5 end-type bristles; margin with about 14 triaenid bristles with small paired teeth (teeth not shown in Figure 53h); inner margin with 6 dwarf bristles (distal of these longer than others). Basale: ventral margin with 12 triaenid bristles (with 8–10 pairs of distal teeth excluding terminal pair) and 2 longer, spinous, distal bristles; dorsal margin with proximal hairs followed by 9 short or medium bristles and 2 long bristles; medial side with 5 short bristles near ventral margin, and long hairs on dorsal half of joint. Exopodite hirsute, tip not quite reaching distal end of 1st endopodial joint, with 2 ventral bristles (distal of these quite short). Endopodite: ventral margin of 1st joint with 8 bristles (7 of these forming row extending onto medial surface); ventral margin of 2nd joint with bristles forming 2 distal groups (3 bristles in proximal group, 2 in other); dorsal margin and medial surface near dorsal margin with about 35 bristles (about 3 of the larger cleaning bristles with stout marginal spines); end joint with 3 long bare claws, 1 long, spinous, lateral bristle (spines not shown in figure 53h, and 2 ventral bristles (1 long, 1 short).

Maxilla (Figures 53i, 54a): Epipodial appendage long, slender, tapering to slender point, with minute spines near ventral margin. Endite I with 3 stout bristles; endite II with 1 small bristle and 2 stout bristles; endite III with 3 or 4 fairly stout bristles; 9 short bristles present anterior to bases of bristles of endite III. Basale: dorsal margin hirsute, with 6 proximal bristles (with bases on medial side) and about 7 distal bristles; ventral margin with 15 short bristles, 2 long distal bristles and 1 long, spinous, terminal bristle; medial surface with 6 distal bristles (longest of these near ventral margin); lateral side with 1 short proximal bristle. Exopodite: small lobe with 1 long and 2 short bristles. Endopodite: 1st joint spinous, with 1 short anterior bristle proximal to middle and 1 long spinous beta-bristle; end joint with 5 spinous bristles.

Fifth Limb (Figure 54b, c): Dorsal margin of comb slightly convex, with abundant short hairs that continue along anterior margin, and 5 small proximal bristles; lateral side with stout, spinous, exopodial bristle just reaching distal end of comb, 3 minute bristles just posterior to base of stout exopodial bristle, and 5 small bristles near ventral margin posterior to base of stout exopodial bristle; ventral margin with long bristles with short marginal spines and shorter bristles with long flaring hairs near tip (Figure 54c).

Sixth Limb (Figure 55a): Anterior margin with a well-defined upper suture ventral to trunk middle and a poorly defined lower suture near juncture of trunk and skirt. Anterior margin dorsal to upper suture with bristles forming 3 rows: 18 short, stout, spinous bristles in inner row, about 20 slender spinous bristles in middle row (distal of these longer than others), and about 23 short, very slender, spinous bristles in outer row. Anterior margin between upper and lower sutures with 5 spinous bristles in inner row, 5 spinous bristles in middle row (the distal of these very long), and 6 spinous bristles in outer row. A single row of about 15 short, slender, spinous bristles present near anterior margin of skirt between lower suture and ventral margin of skirt. Lateral flap with 5 slender hirsute bristles (flap of illustrated limb not in its usual lateral position). Ventral margin of skirt with numerous bristles continuing almost to posterior tip of skirt. Posterior tip of skirt with 3 short, stout, hirsute bristles. Five small bristles in place of epipodial appendage. No medial spines present in anterodorsal corner of trunk. Limb hirsute.

Seventh Limb: Each limb with about 90 bristles, 45 on each side; each bristle with up to 8 bells; most bristle-bearing joints with 2 bristles, 1 on each side, but distal joints with 3 or 4 bristles, 1 or 2 on each side. Terminus with opposing combs, each with about 20 teeth of various types (Figure 54d).

Furca (Figure 54e-g): Each lamella with 4 stout main claws, 1 slender spinous bristle between claws 3 and 4 (closer to claw 4), and 7 additional slender bristles following claw 4; main claws with teeth of equal length forming medial and lateral row along concave margin; each pair of teeth with minute tooth between them (Figure 54g); bristle between claws 3 and 4 shorter than claw 4; bristles following claw 4 with stout and slender spines along anterior and posterior margins; main claws with hairs along convex margin; right lamella with hairs along anterior margin; hairs present on medial side of main claws near base and between and following bristles posterior to main claws; space between claw 4 and following bristle slightly wider on right lamella than on left lamella.

Rod-shaped Organ (Figure 53j): Elongate with suture proximal to widened middle part, tapering to rounded tip.

Eyes: Medial eye without dark pigment, bare (Figure 53j). Lateral eye about same size as medial eye, pigmented black, with about 46 ommatidia (outline of eye shown in Figure 53a).

Upper Lip Figure 53k): Each lobe with a few minute slender anterior spines, and long hairs along ventral and posterior surfaces; a lateral hirsute flap present on each side of mouth.

Posterior of Body (Figure 54h): Hirsute; dorsal process represented by small bulge with long hairs.

DESCRIPTION OF ADULT MALE (Figure 56, 57).—Carapace more elongate than that of female, and with hairs forming vertical row near posterior (Figure 56a).

Ornamentation: Similar to that of female.

Infold: Not examined.

Size: USNM 157415, length 3.8 mm, height 2.5 mm; USNM 157721, length 3.6 mm, height 2.6 mm.

First Antenna (Figure 56b): 1st joint with medial hairs near ventral margin. 2nd joint: dorsal margin with 4 bristles; medial side spinous; lateral side with 4 distal bristles and long hairs in distal ventral corner. 3rd joint: short ventral margin with 1 short bristle; long dorsal margin with 11 bristles. 4th joint: ventral margin with 5 terminal bristles (1 of these very small); dorsal margin with 1 long spinous bristle. 5th joint: dorsal margin with single protuberance distal to middle; ventral margin slightly undulate; sensory bristle with abundant filaments of which 8 at tip thicker than others. 6th joint with fairly short medial bristle near dorsal margin. 7th joint: a-bristle claw-like, bare, about equal in length to combined lengths of joints 6–8, base of bristle on short pedestal; b-bristle about 4 times length of a-bristle, with about 13 marginal filaments; c-bristle very long, tip broken off, with 60 filaments on remaining part (filaments with narrow flare near base). 8th joint: d- and e-bristles bare, broken off on both limbs of specimen examined, but remaining part more than twice length of a-bristle; f-bristle very long, tip broken off, with 60 filaments on remaining part (filaments with narrow flare near base); g-bristle same length as f-bristle, with about 21 marginal filaments.

Second Antenna: Protopodite bare except for minute distal medial bristle (Figure 56c). Endopodite (Figure 56c,h): 1st joint with 2 minute proximal bristles and 4 small bristles near middle; 2nd joint very long, with 4 small distal bristles; 3rd joint reflexed on 2nd, with proximal triangular process bearing long bristle; tip of 3rd joint rounded, weakly ridged, and with subterminal, weakly ringed bristle. Exopodite (Figure 56d): 1st joint with minute spines along concave margin and small, straight, medial, terminal spine; bristle of 2nd joint as long as bristles of joints 3–8, with natatory hairs, no spines; bristles of joints 2–8 with natatory hairs, no spines; 9th joint with 3 long, 1 medium, and 1 short bristle, all with natatory hairs, no spines; joints 2–8 with slender basal spines; basal spine of joint 8 about equal in length to length of dorsal margin of 9th joint; lateral spine of 9th joint small with rounded tip; joints 2–8 with short spines on lateral terminal margin, and long hairs along distal dorsal edge.

Mandible (Figure 56e): Coxale endite broken off on both limbs of specimen examined; small bristle present near base of ventral branch. Basale endite: tip with 1 very long and 5 or 6 shorter end-type bristles; ventral margin of endite with 14 triaenid bristles with minute, paired teeth near tip (some of these bristles could be on ventral margin of basale); inner margin of endite with 6 dwarf bristles forming row (distal of these longer than others). Basale: ventral margin with 9 short spinous bristles and 2 long, spinous, distal bristles (the short bristles have distal teeth so minute that they do not appear to be of triaenid type); dorsal margin with 10 short bristles and 2 long distal bristles; medial side with 3 minute bristles near ventral margin; lateral side with 2 minute bristles near ventral margin. Exopodite hirsute, with tip reaching just past distal edge of 1st endopodial joint, with 2 bristles on ventral margin (distal of these short). Endopodite: 1st joint with 8 bristles on ventral margin (7 of these form row extending onto medial side); ventral margin of 2nd endopodial joint with bristles forming 2 groups (3 bristles in proximal group, 2 in other); dorsal margin and medial side of 2nd joint with abundant bristles (none of the cleaning bristles with stout marginal spines as on female); end joint with 3 stout claws, 1 long, stout, lateral bristle, and 2 ventral bristles.

Maxilla (Figure 57a): Epipodite with slender pointed tip reaching past middle of dorsal margin of basale, with minute spines near ventral margin. Endite I with 1 minute bristle and 3 long stout bristles; endite II with 1 minute bristle and 2 long stout bristles; endite III with 3 long bristles; 7 short slender bristles present distal to bases of bristles of endite III. Basale: dorsal margin spinous, with 5 proximal bristles (bases on medial side) and 5 or 6 distal bristles; medial side with 5 distal bristles (longer of these near ventral margin), and with proximal spines near ventral margin; lateral side with 1 short proximal bristle; ventral margin with 12 or 13 short bristles, 2 long distal bristles, and 1 very long, spinous, terminal bristle. Exopodite consisting of lobe with 3 short bristles. Endopodite: 1st joint spinous, with 1 small bristle proximal to middle of anterior margin, and long beta-bristle; end joint with 6 terminal bristles.

Fifth Limb (Figure 57b): Dorsal margin of comb with 4 minute bristles proximal to low process; anterodorsal margin hirsute and sloping gradually to base of 1st anteroventral bristle; exopodial and ventral bristles similar to those of adult female.

Sixth Limb (Figure 57e): 4 small bristles in place of epipodial appendage; 1 limb with 2 bristles at posterior tip of skirt, other with 3 (possibly 4); limb otherwise similar to that of adult female, but remaining bristles not counted.

Seventh Limb: Single limb examined with 77 bristles, 38 or 39 on each side; each bristle with up to 6 bells. Terminus similar to that of adult female.

Furca and Rod-shaped Organ (Figure 57 c,f): Similar to those of adult female.

Eyes: Medial eye similar to that of adult female (Figure 57c,f). Lateral eye slightly larger than medial eye, about 15 percent longer than that of adult female, pigmented black; ommatidia not counted but appearing to have number similar to that of female (Figure 56f).

Upper Lip (Figures 56g 57g): Similar to that of adult female, but anterior spines appear to be short hairs rather than spines.

Posterior of Body: Similar to that of adult female.

Y-Sclerite (Figure 57d): Arcuate.

DESCRIPTION OF JUVENILE FEMALE (probably instar II) (Figure 55b-k).—Carapace shape and ornamentation similar to that of previously described female (Figure 55b).

Infold: Not examined.

Size: USNM 157627, length 1.18 mm, height 0.94 mm; USNM 157628, length 1.19 mm, height 0.92 mm.

First Antenna (Figure 55c): 1st joint with long lateral and medial hairs near ventral margin, and minute spines forming medial row near distal margin. 2nd joint: long medial and lateral hairs near ventral margin; dorsal margin with few long hairs and 1 distal spinous bristle; lateral side with 1 distal bristle. 3rd joint: short ventral margin with 1 short bristle; long dorsal margin with 1 spinous bristle proximal to middle; lateral side with long hairs near dorsal margin. 4th joint: short dorsal margin with 1 long, spinous, terminal bristle; long ventral margin with few long hairs but no bristles. 5th joint: dorsal margin with stout tooth proximal to middle; lateral and medial sides with few long hairs near dorsal margin; sensory bristle of 5th joint with 1 fairly long filament just distal to middle, and 5 long terminal filaments. 6th joint with spinous medial bristle reaching past tip of a-bristle of 7th joint. 7th joint: a-bristle clawlike, bare, about same length as dorsal margin of 5th joint; b-bristle stout, about one and one-half times length of a-bristle, with bifurcate tip, no proximal filaments; c-bristle longer than sensory bristle, with 5 marginal filaments. 8th joint: d- and e-bristles bare, with blunt tips just reaching past tip of sensory bristle of 5th joint; f-bristle bent dorsally, with 3 or 4 short proximal filaments on ventral margin; g-bristle reaching past tip of sensory bristle but shorter than c-bristle, with 5 marginal filaments.

Second Antenna: Protopodite similar to previously described female. Endopodite: 1st joint with 1 short distal bristle; 2nd joint bare, with well-defined sutures separating it from 1st and 3rd joints; 3rd joint with long terminal filament with blunt tip. Exopodite (Figure 55d): similar to that of previously described female except with only 3 bristles on 9th joint (1 long bristle with few small, proximal, ventral spines, and natatory hairs; 1 short bristle with short, closely spaced, marginal spines along both margins; and 1 very short bare bristle).

Mandible: Coxale endite (Figure 55e): ventral branch broken off; small bristle present near base of ventral branch; ventral margin of dorsal branch with 3 nodes followed by 2 backward pointing, curved processes with spines along concave margins; spines present along margin between processes and tip of branch; tip of dorsal branch with long bristle; dorsal margin of dorsal branch with few serrations. Basale endite: tip with 3 end-type bristles; ventral margin with 2 triaenid bristles, each with 4 pairs of widely spaced proximal spines and about 12 pairs of distal marginal teeth decreasing in length distally along bristle; also present, 1 dwarf bristle with length about one-half that of triaenid bristles. Basale: ventral margin with 1 triaenid bristle with 7 pairs of slender, widely spaced, proximal spines and 8 pairs of distal teeth excluding terminal (similar to those on basale endite); dorsal margin with 2 short bristles near middle, and 2 long distal bristles; medial side with spines and hairs. Exopodite reaching past distal dorsal margin of 1st endopodial joint, with 2 ventral bristles (distal of these short). Endopodite: ventral margin with 3 long spinous bristles; ventral margin of 2nd joint with distal bristles forming 2 groups (1 bristle in proximal group and 2 in other); dorsal margin with 3 long stout bristles; medial side with 1 long spinous bristle near distal dorsal corner and 4 cleaning bristles (largest of these with stout marginal spines); end joint with 3 long stout claws, 1 long lateral bristle, and 2 ventral bristles (1 long, 1 short).

Maxilla: Epipodial appendage long, slender, tapering to slender tip. Endite I with 1 small bristle and 1 long stout bristle; endites II and III combined with 1 short bristle and 3 long stout bristles. Basale: dorsal margin spinous, with 1 short, spinous, proximal bristle (actually on medial side) and 1 long distal bristle; ventral margin with 2 short spinous bristles, 2 long, spinous, distal bristles, and 1 very long, spinous, terminal bristle; medial side with 1 long distal bristle near ventral margin, and spines proximally, distally, and along ventral margin. Endopodite: 1st joint spinous, with 1 short bristle proximal to middle of anterior margin, and 1 long beta-bristle; end joint with 5 bristles. Exopodite consisting of small lobe with 3 bristles (1 long, 2 short).

Fifth Limb: Short hairs of comb along both distal half of dorsal margin and anterodorsal corner becoming slightly longer on anterior margin; lateral side with stout, spinous, epipodial bristle just reaching past end of comb, 3 minute bristles just posterior to base of stout epipodial bristle, and 5 small bristles near ventral margin in vicinity of base of stout epipodial bristle (2 bristles just posterior, and 3 just anterior to base of stout epipodial bristle); bristles along ventral margin similar to those on comb of previously described female.

Sixth Limb (Figure 55f): Limb hirsute; anterior margin with 1 distinct suture; margin dorsal to suture with 1 short, spinous, medial bristle in dorsal corner, and 1 long spinous bristle immediately above suture.

Seventh Limb (Figure 55g): Small, bare.

Furca (Figure 55h): Each limb with 4 stout claws followed by 1 short, stout, spinous bristle; teeth along posterior margin of main claws consisting of long teeth separated by 3 or 4 smaller teeth (distribution of teeth differs from that of previously described female); hairs present on lamella following claws; all claws distinctly separated from lamella by suture.

Rod-shaped Organ (Figure 55j): Similar to that of previously described female.

Eyes: Medial eye similar to that of previously described female (Figure 55j). Lateral eye about same size as medial eye, pigmented black, with about 15 ommatidia (Figure 55i).

Upper Lip (Figure 55j): Similar to that of previously described female but no anterior spines observed.

Posterior of Body (Figure 55k): Similar to that of previously described female.

Y-Sclerite (Figure 55k): Dorsal socket near middle; parts anterior and posterior to socket forming distinct angle.

Gill-like Structures: 7 well-developed structures on each side of posterior of body.

COMPARISONS.—The new species, T. tanzania, differs from T. brevis (Müller, 1890) in the morphology of the sensory bristle on the 5th joint of the 1st antenna of the female. The sensory bristle of T. tanzania bears 7 short marginal filaments, whereas this bristle on T. brevis bears 2–4 short marginal filaments. Of course, the variability of this character on both species is not known, but in other species in the subfamily, the number of short filaments is fairly constant, although occasionally a rare specimen has been observed to vary from the norm (e.g., in Leuroleberis zealandica (Baird, 1850) (see Kornicker, 1979).

The distal epipodial bristles on the 6th limb of specimens of T. tanzania collected off Madagascar appear to be longer than those bristles on specimens collected off Tanzania. In that respect the Madagascan specimens are similar to Tetraleberis maddocksae. The latter species has very slender spines on the bristles of the exopodite of the 2nd antenna, whereas the spines are stout on T. tanzania. Adult males of the 2 species will be difficult to separate, because spines are not present on the exopodial bristles of adult males of T. tanzania, and also may not be present on adult males of T. maddocksae, which is unknown.

Tetraleberis species 1

MATERIAL.—USNM 157416, 1 juvenile (instar I) from station 9–446, Indian Ocean

DISTRIBUTION.—Off Somalia at depth of about 65 m (Figure 44). Because of having only 1 early juvenile of this species in the collection it has been left in open nomenclature.

DESCRIPTION OF JUVENILE, INSTAR I (Figures 58, 59, Plate 41).—Carapace oval in lateral view with fairly deep incisur and pointed rostrum (Figure 58a, Plate 41a,b).

Ornamentation: Anterior margin without scalloped ridge; no vertical ridge present posterior to incisur; surface with minute reticulations (Plate 41c–f,h); bristles emerging from open pores both with single rim (Plate 41h) and concentric rims (Plate 41c–f); minute pores without bristles also present (Plate 411f).

Infold: Typical for genus.

Selvage: Selvage along anterior margin of rostrum with marginal fringe (Plate 41g).

Size: USNM 157416, length 1.33 mm, height 1.10 mm.

First Antenna (Figure 58b–d): Joints 1–6 hirsute. 3rd joint with 1 long dorsal and 1 short ventral bristle. 5th joint with teeth forming row along dorsal margin; sensory bristle without filaments. 6th joint with long, spinous, medial bristle. 7th joint: a-bristle clawlike, pectinate along dorsal margin; b-bristle about same length as a-bristle, bare; c-bristle reaching past sensory bristle of 5th joint, bare. 8th joint: d- and e-bristles about same length as sensory bristle, bare with blunt tips; f-bristle bent dorsally, bare; g-bristle about same length as c-bristle, bare.

Second Antenna (Figure 58e,f): Protopodite with short, medial, distal bristle. Endopodite 3-jointed: 1st and 2nd joints bare; 3rd joint with long terminal bristle. Exopodite with 9 joints: 1st joint with medial spine on distal margin; bristle of 2nd joint reaching 9th joint, with numerous slender marginal spines; bristles of joints 3 and 4 with slender ventral spines and natatory hairs; bristles of joints 5–8 with natatory hairs, no spines; 9th joint with 2 bristles (dorsal of these with short hairs, other with long natatory hairs, no spines); joints 3–8 with stout basal spines; 9th joint with stout lateral spine; joints 2–8 with minute spines forming row along distal margin.

Mandible (Figure 58g): Coxale endite broken off both limbs of USNM 157416, but slender bristle present near base of ventral branch (not shown on illustrated limb). Basale endite: tip with 2 end-type bristles; ventral margin with 1 fairly long dwarf bristle and 1 long bristle with marginal hairs. Basale: ventral margin with 1 triaenid bristle near endite (paired teeth of triaenid bristle decreasing in size distally along bristle); dorsal margin with 1 bristle near middle and 2 terminally. Exopodite hirsute, reaching past distal end of 1st endopodial joint, with 2 ventral bristles (distal of these short). Endopodite: 1st joint with 2 long ventral bristles (left limb only of USNM 157416 also with 1 dorsal bristle); ventral margin of 2nd joint with 1 long, spinous, terminal bristle; dorsal margin and medial surface of 2nd joint near dorsal margin with total of 6 bristles; medial side of 2nd joint with long spines forming rows; end joint with 3 long, spinous, clawlike bristles and 1 long, spinous, ventral bristle.

Maxilla (Figure 58h): Epipodial appendage about two-thirds length of dorsal margin of basale. Endites with total of 4 long bristles. Basale: dorsal margin with 1 proximal bristle with base on medial side; ventral margin with 3 long distal bristles and 1 very long terminal bristle. Exopodite consisting of small lobe with 1 long and 2 short bristles. Endopodite: 1st joint with 1 short anterior bristle and 1 long beta-bristle; end joint with 4 or 5 bristles.

Fifth Limb: Present but not examined in detail.

Sixth Limb (Figure 59a): Hirsute, but without bristles.

Seventh Limb: Absent.

Furca (Figure 58i): Each lamella with 4 claws, but no bristles; all claws with teeth along posterior margins; claws 1 and 2 with teeth near middle longer than others, especially on claw 2; sutures at bases of claws 3 and 4, if present, not well developed.

Rod-shaped Organ Figure 59b): Elongate with unevenly rounded tip.

Eyes: Medial eye bare, without pigment (Figure 59b). Lateral eye about same size as medial eye, with amber pigment and about 20 ommatidia (Figure 59b).

Upper Lip (Figure 59b): Consisting of 2 hirsute lobes, middle saddle, and hirsute lateral flaps, 1 on each side of mouth.

Posterior (Figure 59c): Spinous but without dorsal process.

COMPARISONS.—No other species in the genus has a row of minute teeth along the dorsal margin of the 5th joint of the 1st antenna.

Tetraleberis species indeterminate

MATERIAL.—USNM 157698, 1 juvenile (instar I), sta LK-35, Indian Ocean (Figure 60a); this specimen is without teeth or processes on dorsal margin of the 5th joint of the 1st antenna, has a bare clawlike a-bristle on the 1st antenna, bears 4 claws on each lamella of the furca, and does not have a vertical ridge posterior to the incisur on the carapace; length 1.07 mm, height 0.86 mm. USNM 157699, 2 juveniles (instar I), sta 9446 (Figure 60b,c), Indian Ocean; both specimens similar to previous specimen (USNM 157698), except a-bristle of 1st antenna pectinate along dorsal margin; length 0.91 mm, height 0.79 mm; length 0.92 mm, height 0.77 mm. USNM 134476, 1 juvenile (instar I), length 0.87 mm, height 0.70 mm, from Kagami-ga-ura Bay, Tateyama, Japan (Figure 61); the 1st antenna is without a node on the dorsal margin and the bristles of the 7th and 8th joints are without filaments; no bristles are on the 6th limb, and the 7th limb is absent; each furcal lamella has 4 main claws but no bristle between claws 3 and 4, and spines are present in place of bristles following claw 4. USNM 157801, 4 juveniles, from Bab el Mandeb; may be T. tanzania, but insufficiently developed to be certain.

DISTRIBUTION.—Off Somalia at about 65 m; off Zanzibar Island at 20 m; Bab el Mandeb at 24 m; in plankton (0–1 m below surface) off Tateyama, Japan, bottom depth 3–6 m. (Figure 44).

Amboleberis, new genus

ETYMOLOGY.—The generic name derived from the Greek ambon (ridge) plus leberis (sloughed skin) in reference to the vertical ridge posterior to the incisur of species in this genus. Gender feminine.

TYPE-SPECIES.—Asterope americana Müller, 1890.

COMPOSITION AND DISTRIBUTION (Figure 39).—Amboleberis antyx: Madagascar. Amboleberis americana: Pacific Ocean: Panama, Costa Rica. Atlantic Ocean: South Carolina, Georgia and Florida Shelf, Dry Tortugas, Brazil, Bahamas, Florida keys. Gulf of Mexico: Florida, Texas. Caribbean Sea: Belize. Depth range surface to 53.5 m.

Two species are referred to this genus: Amboleberis americana (Müller, 1890) and Amboleberis antyx, new species.

DIAGNOSIS OF FEMALE.—Carapace with vertical ridge with dorsal end just posterior to inner end of incisur and ventral end curving posteriorly to intercept ventral margin of valve (also on carapace of adult male); valves oval in lateral view with deep anterior incisur;

Ornamentation: Surface without abundant shallow fossae; bristles scattered over valve surface emerging both from open pores without rims and open pores with concentric rims; pores without bristles also present; abundant pits visible on surface when viewed at very high magnification (×10,000); anteroventral and anterodorsal borders without scalloped edge.

First Antenna: Sensory bristle of adult female of A. americana with 7 short proximal and 8 or 9 long terminal filaments; sensory bristle of juvenile female (instar IV?) of A. antyx with 5 short proximal and 7 long terminal filaments. Clawlike a-bristle of A. americana bare, that of A. antyx with teeth proximally along dorsal margin.

Second Antenna: Most exopodial bristles with stout ventral spines; exopodial joints 2–8 with stout basal spines.

Maxilla: Exopodite with 3 bristles present.

Fifth Limb: Dorsal and ventral margin of comb subparallel.

Seventh Limb: Terminus consisting of opposing combs, 1 on each side. Adult female of A. americana with 64 bristles; juvenile female (instar IV?) A. antyx with 39 or 40 bristles.

Furca: Each lamella with 4, stout claws, 1 short bristle between claws 3 and 4, but closer to claw 4, and several bristles following 4th claw (6 bristles on adult A. americana, 4 on instar IV? A. antyx).

COMPARISONS.—The vertical ridge posterior to the incisur and intersecting the ventral margin of each valve distinguishes Amboleberis from Tetraleberis the only other genus in the tribe. A similar ridge is present on the carapace of Cyclasterope fascigera (see Plate 1a).