Igene bryx Kornicker 1992

Igene bryx

ETYMOLOGY.—From the Greek bryx (depth of the sea) in reference to the abyssal depth at which the species was collected.

HOLOTYPE.—MNHN Os 451, undissected adult female in alcohol.

TYPE LOCALITY.—Sta 87-CH, 3 Apr 1977, SE Glorioso Islands, 11°44′S, 47°35′E, depth 3716 m.

PARATYPES.—Sta 87-CH: USNM 193749, 1 ovigerous female on slide and in alcohol; USNM 193750, 1 adult female in alcohol (body posterior to maxilla missing from specimen); Paris, 1 juvenile (length 0.94 mm, height 0.58 mm; 6 claws on each lamella of furca).

DISTRIBUTION.—Collected only at type locality.

DESCRIPTION OF ADULT FEMALE (Figures 68–71).—Carapace oval in lateral view with prominant rostrum and broad incisur (Figures 68a,b,d–f, 71j). Posteroventral corner with small but distinct projecting caudal process (Figure 68h,i). In lateral view anterior corner of rostrum pointed, posterior corner rounded (Figure 68b,e), and distal edge concave. Outer surface of carapace with sparsely distributed unbranched bristles (Figure 68e,i). Carapace uncalcified (preserved specimens flexible).

Infold: Infold of rostrum with short list extending from posterior corner (Figure 68g). Narrow list with anterior end in vicinity of anteroventral striae continues along ventral and posterior parts of infold and terminates in posterior juncture of dorsal hinge; distance between list and valve edge greatest in vicinity of caudal process and just anterior to process; part of infold between list and valve edge opaque whereas part of infold between list and inner margin of infold transparent. Infold of rostrum with 8 or 9 spinous bristles in row oblique to anterior edge (Figure 68g), 2 short bristles between rostral list and incisur, and 1 short bristle just posterior to ventral end of incisur (Figure 68g). Anteroventral infold with about 10 striae but no bristles; anterior of ventral infold without bristles; posterior with about 20 small bristles along list; list of posterior infold (including caudal process) with about 14 bristles (including about 8 fairly long unbranched bristles) (Figure 68h, not all bristles shown); infold in vicinity of caudal process between list and valve edge with 7 small bristles; ventral and posterior parts of infold between list and inner margin of infold without bristles.

Selvage: Broad lamellar prolongation along anterior, ventral, and posterior margins of carapace and also along anterior part of dorsal margin; prolongation unsegmented (with smooth outer edge) between anterior juncture of dorsal hinge and anterodorsal corner of carapace; prolongation segmented (with fringe of long hairs along outer edge) along anterior and ventral edge of rostrum; prolongation divided at inner end of incisur; prolongation along ventral edge of incisur broad, striate at inner end of incisur, and with fringe of hairs along outer edge (Figure 68b,f); prolongation at inner end of ventral edge of incisur and along anterior of ventral margin with long medial bristles (some with bases on prolongation near proximal edge, but most with bases on valve edge); prolongation along posterior of ventral edge of carapace unsegmented and with fringe along outer edge; prolongation narrow (without fringe) along caudal process and on ventral edge of carapace just anterior to process; prolongation between dorsal end of caudal process and posterior juncture of dorsal hinge broad, nonstriated, with long distal fringe on ventral and without fringe on dorsal , and with 2nd narrow prolongation (with distal fringe) along inner of broad prolongation.

Carapace Size: MNHN Os 451, holotype, left valve, length 1.51 mm, height 1.22 mm; USNM 193749, length 1.49 mm, height 1.10 mm; USNM 193750, length 1.49 mm, height 0.90 mm.

First Antenna (Figure 69a,b): 1st joint with medial and lateral spines. 2nd joint with medial and lateral spines and 2 spinous bristles (1 dorsal, 1 lateral). 3rd joint short, dorsal edge longer than ventral, with medial and lateral spines, small distal spines on ventral margin, and 2 or 3 spinous bristles (1 ventral, 1 or 2 dorsal). 4th joint with medial spines and 4 spinous bristles (3 ventral, 1 dorsal). Sensory bristle of long 5th joint with 3 short proximal, 1 longer subterminal, and 4 short terminal filaments. 6th joint fused to 5th, minute, with spinous medial bristle. 7th joint: a-bristle slightly longer than bristle of 6th joint, with short marginal spines; b-bristle about twice length of a-bristle, with 1 short proximal and 4 short terminal filaments; c-bristle same length as sensory bristle of 5th joint, with 3 short proximal and 4 terminal filaments. 8th joint: d- and e-bristles about same length as c-bristle, bare with blunt tips; f-bristle slightly shorter than c-bristle, with 2 proximal and 4 terminal filaments; g-bristle same length as c-bristle, with 4 proximal and 4 terminal filaments. (Not all filaments illustrated.)

Second Antenna: Dorsal half of protopodite with medial spines and hairs (Figure 69c). Endopodite 2-jointed (Figure 69d): 1st joint with 4 bare bristles (bases appear to be on medial ridge that may be part of protopodite); 2nd joint with long ventral bristle with long hairs, and short bare ringed terminal bristle. Exopodite: 1st joint with minute, straight, tubular, medial bristle; bristles of joints 1–8 bare, each only slightly longer than total length of joints 2–9 and each with minute talon-like tip; 9th joint with 6 bristles (4 shortest bristles dorsal, with short marginal spines; 2 longer bristles ventral, with 3 or 4 short distal ventral spines) (Figure 69e); joints 2–8 with 1 or 2 rows of distal spines. (Exopodite of right limb of USNM 193479 (Figure 69e) aberrant in having short 5th, 6th, and 9th joints, and no bristles on joints 5 and 8.)

Mandible (Figure 69f): Coxale endite deeply bifurcate, spinous, with minute ringed bristle near base. Basale: medial surface with rows of spines, abundant long hairs near ventral margin, 3 stout pectinate bristles and 2 short, slender, spinous, ringed bristles at proximal ventral corner, and 1 longer bristle (with long proximal and short distal spines) at midlength; ventral margin with 4 or 5 bristles (2 or 3 proximal bristles shorter) with long proximal and short distal spines; dorsal margin with 3 spinous bristles (1 at about length of margin, 2 terminal); lateral surface with rows of spines and abundant hairs in ventral half. Exopodite about length of dorsal margin of 1st endopodial joint, with hirsute distal pad and 2 subterminal bristles (outer bristle with short spines, inner bristle longer and with wreaths of long spines and small distal spines). Endopodite: 1st joint with 3 spinous ventral bristles, and row of medial spines near distal dorsal corner. 2nd joint: proximal medial surface with rows of spines; ventral margin with spinous bristles forming 2 groups (2 in proximal group, 3 in distal); dorsal margin with spinous bristles forming 2 closely spaced groups (proximal group with 3 spinous bristles, distal with 6). 3rd joint with 3 claws (dorsal claw short, medial claw long with few ventral teeth at midlength, lateral claw longest) and 3 bristles.

Maxilla: Dorsal margin of precoxale and coxale with dorsal fringe of hairs. Coxale with fairly long plumose dorsal bristle (Figure 71d). Endite I broad with 10 spinous and pectinate bristles (Figure 71a); endite II narrow, with 6 spinous and pectinate bristles (Figure 71b); endite III narrow, with proximal hairs and about 7 spinous and pectinate bristles (Figure 71c); 1 proximal bristle on either 1st or 2nd endite (Figure 71b,d). Basale with 2 long spinous bristles (1 ventral, 1 medial, none dorsal) (Figure 71d). Exopodite short with 3 bristles (proximal short with few marginal spines, outer of 2 long terminal bristles with long proximal hairs and short distal spines, inner long bristle bare or with short spines) (Figure 71d). Endopodite: 1st joint with spines along anterior margin, 1 long alpha-bristle with long hairs at midlength and spine at tip, and 3 beta-bristles (bare or with few spines, all with tubular tips; posterior bristle on small pedestal) (Figure 71d,f,g). 2nd joint with 3 bare lateral a-bristles with tubular tips, 2 b-bristles (anterior ringed, with marginal spines, posterior claw-like with marginal teeth), 2 ringed c-bristles with tubular tips, and 3 pectinate d-bristles (2 anterior claw-like, posterior bristle ringed) (Figure 71e–g).

Fifth Limb: Epipodite with 41 or 42 bristles. Endites I and II each with 6 or 7 bristles (Figure 69g,h); endite III with 9 or 10 bristles (Figure 69i). 1st exopodial joint: main tooth with 4 pectinate teeth (proximal tooth slender with long thin spine-like cusps; following tooth stouter, with 5 pointed cusps; next tooth stoutest, with 5 pointed cusps (proximal cusp much larger than others); protuberance anterior to distal tooth smooth, rounded (Figure 69j,k)); 1 spinous bristle just proximal to main tooth; anterior side of joint with 2 long bristles at midwidth and 1 short bristle on small lobe at proximal outer corner (Figure 69j). 2nd exopodial joint: large flat triangular tooth; inner edge of tooth obscured and teeth not observed; posterior side with stout c-bristle and 3 bristles forming row (1 small bristle on each side of large bristle) (Figure 69l). Inner lobe of 3rd joint obscured (with about 3 bristles); outer lobe with 2 hirsute bristles; fused 4th and 5th joints with total of 6 spinous bristles (Figure 69m).

Sixth Limb (Figure 70a): Single epipodial bristle with long proximal and short distal hairs. Endite I with 2 or 3 short plumose medial bristles and 1 long terminal bristle with wreaths of long hairs; endite II with 1 short spinous medial bristle and 3 long spinous terminal bristles; endite III with 6 or 7 spinous terminal bristles; endite IV with 7 spinous terminal bristles. End joint with 9 hirsute and spinous bristles.

Seventh Limb (Figure 70b,c): Proximal group with 2 bristles (1 on each side) with distal spines and 3 or 4 bells; terminal group with 5 spinous bristles (2 on comb side with 4 or 5 bells; 3 on peg side with 1, 5, and 5 bells). Terminus with about 5 spinous teeth in comb opposite 2 pegs (1 with round tip, other pointed) (Figure 70c).

Furca (Figure 70d): Each lamella with 9 slender claws decreasing in length posteriorly along lamella; claws 1–4 with stout teeth along posterior edge interspersed with smaller teeth; claws 5–9 with slender spine-like teeth along posterior edge, some claws with spines along anterior edge; claws 1–4 or 5 with long medial spines in row near base; long spines on lamella following last claw. Right lamella anterior to left by width of base of claw 1.

Bellonci Organ (Figures 68c, 70e,f): Short, conical, spinous, unsegmented. (On both specimens examined (USNM 193749, 193750) Bellonci organ covered by debris.)

Eyes: Medial and lateral eyes absent.

Upper Lip (Figure 70e,g): Conical with tubular processes on anterior tip.

Brush Organ (Figures 70h, 71h): 10 minute bristles in row on each side of body dorsal to genitalia.

Genitalia (Figures 70h, 71h): Yellow oval on each side of body anterior to anus.

Anterior of Body: With single round process midway between Bellonci organ and upper lip (Figure 70e,g). Sclerotized process projecting laterally on body at each side of upper lip (Figure 70e,g).

Posterior of Body (Figure 70h): Posterior spinous; posterodorsal corner evenly rounded, bare.

Y-Scelerite (Figure 70h): Dorsal branch long; ventral branch short, bifurcate distally.

Eggs: Single egg of USNM 193749 with well-developed internal embryo having 2nd antenna with exopodite and shell with incisur (Figure 71i); maximum length of egg 0.37 mm; lateral eyes absent.

DISTRIBUTION.—Widespread between latitudes of 45°N and 53°S, generally at depths of intertidal to 560 m, possibly deeper on the continental slope (Cohen and Kornicker, 1987:2).

COMPOSITION.—This family includes 3 genera (Cohen and Kornicker, 1987:1–8): Rutiderma Brady and Norman, 1896; Alternochelata Kornicker, 1958; and Scleraner Kornicker, 1975a. Only Rutiderma are in the present collection.

Rutiderma Brady and Norman, 1896

TYPE SPECIES.—Rutiderma compressa Brady and Norman, 1896:673.

DISTRIBUTION.—Widespread between latitudes of 45°N and 53°S and depths of intertidal to 317 m (questionably collected at 1834 m) (Cohen and Kornicker, 1987:3). Hartmann (1974:237) reported juveniles from the Pacific coast of South Africa and in the vicinity of Mozambique, Indian Ocean, as Rutiderma cf. compressa Brady and Norman.

COMPOSITION.—Including 2 new species described herein the genus contains 28 species plus about 11 left in open nomenclature (Cohen and Kornicker, 1987:2; Kornicker, 1991:81).