Prionotoleberis gyion Kornicker 1974

Prionotoleberis gyion

ETYMOLOGY.—The specific name gyion from the Greek noun meaning “limb.”

HOLOTYPE.—Juvenile male, USNM 120344; valves in alcohol, some appendages on slides, others in alcohol.

PARATYPE.—Female instar in the collections of the Zoological Station of Naples, Italy; valves in alcohol, some appendages on slides, others in alcohol.

TYPE-LOCALITY.—Gulf of Naples, Italy, near Benta Palumma.

MATERIAL.—1 juvenile (estimated at N-1 instar) collected in muddy sand from near Benta Palumma, Gulf of Naples, at depth of 55 m, on 27 April 1966 by L. S. Kornicker; 1 juvenile (estimated as N-2 instar) collected in same sample as instar above.

DISTRIBUTION.—Gulf of Naples.

DESCRIPTION OF MALE INSTAR (Figure 18).—Carapace elongate, oval in lateral view with height 49 percent of length; anterior and posterior ends evenly rounded (Figure 18a); inferior tip of rostrum with short broad spines (not readily visible except under oil immersion); inner angle of incisur acute with lateral overlap of dorsal edge.

Ornamentation: Shell smooth without hairs or pits; valves almost opaque, but with lateral eyes and muscle scars visible in lateral view.

Infold (Figures 18d–f, 19c–f): Broad anteriorly and posteriorly, narrow ventrally; infold above incisur with about 12 bristles in row parallel to upper edge of incisur, 16 long (some spinous) and 14 short bristles in row parallel to anterodorsal margin of valve, about 7 bristles on low transverse ridge, and 6 bristles between the bristles on transverse ridge and anterior margin of valve; infold below rostrum with about 25 long, and numerous very short, bristles followed by about 12 long bristles evenly spaced along the ventral margin; posterior ridge with broad transparent spines and short spines; infold between posterior ridge and posterior margin of valve with numerous bristles in row parallel to posteroventral margin, and 5 or 6 faint minute processes.

Hinge: Linear along dorsal margin.

Marginal pore canals: Fairly numerous along free margins.

Central muscle scars (Figure 15b,c): Consisting of 14–16 individual oval scars.

Selvage: Lamellar prolongation narrow, bare, except for fringe of short hairs along anterodorsal margin of each valve, and long hairs along lower edge of incisur (Figure 19c–d).

Size: Length 1.54 mm, height 0.75 mm; height 49 percent of length.

Micromorphology based on scanning-electron photomicrographs: Outer surface with scattered long bristles emerging from open pores ringed by concentric ridges (Figure 19a); minute simple pore often near ringed pore (Figure 19a); open pores with raised rim widely spaced on surface of valve (Figure 19b). Fringed lamellar prologation present on selvage along lower margin of incisur (Figure 19c–d). Posterior list with flaplike bristles with pores and tubes at their bases alternating with simple bristles emerging from open pores (Figure 19e–f).

First antenna (Figure 18g): 1st and 2nd joints with clusters of spines medially and laterally; 2nd joint with spinous distolateral bristle, and long spinous subterminal bristle on dorsal margin; 3rd joint with short ventral bristle and 6 spinous dorsal bristles; 4th joint with 3 spinous terminal bristles, 1 dorsally, 2 ventrally; 3rd and 4th joints separated by weak suture; sensory bristle of 5th joint with thick trunk, 1 short proximal filament and 6 terminal filaments; 6th joint with spinous medial bristle overreaching claw of 7th joint. 7th joint with a-, b-, and c-bristles: b-bristles clawlike, curved; b-bristle with 4 marginal filaments; c-bristle with 8 marginal filaments. 8th joint with e-, f-, and g-bristles: e-bristle about one half length of g-bristle; f-bristle at right angles to stem, with about 6 short spines proximally, and 5 marginal filaments distally, 2 of the filaments with marginal spines; g-bristle with 6 marginal filaments.

Second antenna (Figure 18h): Protopodite with medial distal bristle, 1 or 2 spines along anterior margin, and clusters of spines on medial surface. Endopodite 3-jointed, with long bristle near middle of 3rd joint. Exopodite: 1st joint with medial spines in cluster subterminally near inner margin; joints 3–9 with large basal spines; joints 2–8 with short distal spines in row along lateral and medial margins; joints 3–9 with short peg and spines present on corner of joint opposite basal spine; bristle of 2nd joint terminating close to proximal margin of 9th joint, and with ventral margin having stout spines proximally and slender spines distally; bristles of joints 3 and 4 with many ventral spines; bristles of joints 5–7 with few; bristles of joints 3–8 with natatory hairs; 9th joint with 2 unequal long bristles with natatory hairs, and 2 unequal short bristles with marginal spines.

Right mandible (Figure 18i): Basale: lateral surface with clusters of spines; dorsal margin with 3 long spinous bristles, 1 medial near middle, and 2 subterminal; endite with 4 triaenid bristles having 3 pairs of spines distally, 4 spinous bristles, 2 bare dwarf bristles and glandular peg. Exopodite about three-fourths length of 1st endopodite joint, with 2 short bristles and hairs terminally. Endopodite; 1st and 2nd joints each with 3 spinous ventral bristles; dorsal margin of 2nd endopodite joint with stout a-, b-, c-, and d-bristles, 1 short spinous bristle proximal to b-bristles, 1 short spinous bristle medially between a- and b-bristles, 2 short spinous bristles medially between b- and c-bristles, 5 spinous bristles in transverse row medially near d-bristle, 1 long slender spinous bristle between c- and d-bristles, and 1 medium spinous bristle distal and medial to d-bristle; d-bristle with marginal spines; c-bristle stouter and shorter than b- and c-bristles; 3rd endopodite joint with stout dorsal claw and 5 bristles, 3 stout, 2 slender. Coxale endite: ventral branch with sharp spines in 4 rows, and tip with 3 stout spines; dorsal branch with ventral margin with 1 pointed double-tooth followed by 3 rounded double-teeth and 4 small projections; main tooth of dorsal branch with spines along inner margin; dorsal margin of dorsal branch serrate; distal bristle of endite overreaching tip; small medial bristle present near basis of ventral branch.

Left mandible: Left mandible differing from right in having no proximal bristle on dorsal margin of 2nd joint of endopodite, and in having only 1 triaenid bristle, 3 spinous bristles, 2 dwarf bristles, and glandular peg on basale endite (the sparsity of bristles on the endite suggests that it is abnormal).

Maxilla (Figure 18k): Endites covered with debris and could not be observed; in other features, similar to that of female described below.

Fifth limb: Similar to that of female described below.

Sixth limb (appendage with some bristles missing, and coated with much debris; Figure 18j): Anterior margin with 2 endite bristles and short hairs; anteroventral corner with 3 or 4 spinous bristles; anterior margin of lateral sole with 1 spinous bristle and numerous long hairs; ventral margin posterior to lateral sole with hairs followed by 14 (estimated) bristles with long proximal and short distal spines, 2 bristles with long spines, a space without spines and then 5 bristles with long spines; posterior margin and medial surface hirsute: 2 small medial bristles present proximally near anterior margin.

Seventh limb (Figure 18l): Terminus with opposing combs, each comb with about 16 spinous teeth. Bristles in distal group: 6, proximal group: 6, each with 2–4 bells; tip of each bristle elongate, spinous.

Upper lip (Figure 18o): With low unpaired anterior part, and a pair of hirsute lobes posteriorly; each posterior lobe with elongate, hirsute, lateral lobe.

Furca (considerable debris in vicinity of secondary claws making observation difficult; Figure 18m): Each lamella with about 5 stout curved claws and 3 weak secondary claws, some bristle-like; stout claws with teeth along concave margins; claws 1–3 with fine spines along distal part of convex margins.

Eyes: Lateral eye (Figure 18n) pigmented, with about 19 ommatidia; medial eye (Figure 18p) pigmented, about same size as lateral eye.

Rod-shaped organ (Figure 18p): Elongate, expanding near middle and tapering distally.

Gills: 7 elongate gills present on each side of posterior.

DESCRIPTION OF FEMALE INSTAR (Figure 20).—Carapace quite similar to that of male instar described above except for size and minor variations in bristle distribution on inner lamella (Figure 20a–f). Minute indistinct processes (5 or 6) present between posterior list and valve margin.

Size: Length 1.39 mm, height 0.71 mm, height 51 percent of length.

First antenna (Figure 20g): Proximal filament on sensory bristle slightly longer than on male; f-bristle of 8th joint without short proximal spines; d-bristle present as short stump; other features similar to limb of male instar described above.

Second antenna (Figure 20h): Endopodite 3-jointed with long terminal bristle on 3rd joint. Exopodite without cluster of subterminal spines on medial surface of 1st joint, and with 1 short and 2 long bristles on 9th joint. In other features similar to appendage of male instar described above.

Mandible (Figure 20i,j): Basale endite with 3 triaenid bristles, 4 spinous bristles, 2 dwarf bristles and glandular peg. 2nd endopodite joint: short proximal bristle present on dorsal margin; a-, b-, c-, d-bristles with marginal spines. Other features similar to that of male instar described above.

Maxilla (Figure 20k): Epipodial appendage hirsute, pointed distally, less than one-half length of protopodite; proximal endite with 4 bristles, 3 long and 1 short; distal endite with 5 or 6 bristles, 3 long and 1 or 2 short. Basale: ventral margin with 1 short proximal and 1 long distal bristle; dorsal margin with 3 short bristles; medial surface hirsute with 1 short bristle near center anterior to endites.

Endopodite: 1st joint spinous, with 1 short subterminal bristle anteriorly and 1 long bristle posteriorly; 2nd joint with long terminal bristle.

Fifth limb (Figure 20l): Comb: Dorsal margin bare, straight (folded over in illustration); long lateral bristle spinous, considerably overreaching tip of comb; lateral side with 5 short bristles between basis of long bristle and ventral margin of comb; anterior edge with long hairs; ventral margin hirsute, and with numerous spinous bristles.

Sixth limb (Figure 20m): Anterior margin with 2 endite bristles and short hairs; anteroventral corner with 2 or 3 spinous bristles; anterior margin of lateral sole with 1 spinous bristle and numerous long hairs; ventral margin posterior to lateral sole with hairs followed by 14 bristles with long proximal and short distal spines, 2 bristles with long spines, a space without spines but with marginal hairs, and then 5 bristles with long spines; posterior margin and medial surface hirsute.

Seventh limb, rod-shaped organ, eyes (Figure 20n): Similar to those of male instar described above.

Furca: Similar to male instar except for having fewer secondary claws.

Polyleberis, new genus

ETYMOLOGY.—The generic name Polyleberis is from the Greek poly (many) + leberis (sloughed skin). Gender: feminine.

TYPE-SPECIES.—Polyleberis mackenziei, new species.

Additional specimens of the type-species, including adult females, were collected off Mauritania (Kornicker and Caraion, 1974). The diagnosis of the genus is based partly on those specimens.

DIAGNOSIS OF GENUS.—First antenna: Sensory bristle on adult female without short proximal filament and with 7–9 terminal filaments; d-bristle of 8th joint absent or minute. Mandible: Exopodite less than one-third length of dorsal margin of 1st joint of endopodite; no long slender bristle between b- and c-bristles of 2nd joint of endopodite; 2nd and 3rd joints of endopodite separated by suture, and longer than 1st joint. Maxilla: End joint with only 1 long bristle.

COMPARISONS.—The only other genus with a short exopodite on the mandible is Cylindroleberis. Polyleberis differs from that genus in not having a short proximal filament on the sensory bristle on the 1st antenna of the adult female.