“Igene illex, new species
Figures 1-3
ETYMOLOGY.—From the Latin illex (contrary to law, lawless).
HOLOTYPE.—Undissected adult female in alcohol in the collection of the Museum of Victoria.
TYPE LOCALITY.—Slope 6, 34°51.90'S, 151°12.60’E, New South Wales, off Nowra; depth 770 m.
PARATYPES.—Slope 6: ovigerous female on slide and in alcohol. Slope 53: USNM 194008, A-l male on slide and in alcohol; 1 instar I in alcohol; 2 late instars in alcohol.
DISTRIBUTION.—Slope 6,770 m. Slope 53, 996 m.
REMARKS.—The A-l male was described prior to finding an adult female in the collection. Because of that sequence the description of the adult female follows that of the A-l male.
DESCRIPTION OF A-l MALE.—Carapace oval in lateral view with prominant rostrum, broad incisur, rounded posterior, and slight bulge at anteroventral corner. Outer surface with long undivided bristles abundant along margins and sparse elsewhere, and sparse short slender bristles. Carapace of USNM 194008 uncalcified, flexible.
Infold: Infold of rostrum with row of 12 or 13 divided bristles (some spinous) parallel to anterior edge of rostrum; 2 additional bristles on ventral edge near incisur, 1 small bristle present on infold posterior to inner end of incisur, anteroventral infold with 8 striae but no bristles; 2nd of the striae from outer edge of valve continues as narrow list along ventral and posterior margins; list located at about midwidth of infold along anterior 2/3 of ventral margin but close to inner margin of infold along posterior 1/3 of ventral and posterior margins; ventral infold without bristles; infold of posteroventral corner and posterior margin with about 24 bare undivided short bristles between list and shell edge, most bristles close to list; outer edge of posterior infold with numerous minute pores or processes.
Selvage: Broad lamellar prolongation with marginal fringe of long hairs along anterior and ventral margins but narrow without fringe along posterior margin; prolongation segmented along edge of rostrum and along inner part of ventral margin of incisur, prolongation divided at inner end of incisur, anteroventral and anterior half of ventral prolongation with long streamers (some with bases on prolongation near proximal edge, but most with bases on valve edge).
Central Adductor Muscle Attachments: With 3 elongate and about 14 oval attachments.
Carapace Size (length, height in mm): USNM 194008, 1.62, 1.08.
First Antenna: 1st joint with long medial hairs. 2nd joint with long spines along ventral and dorsal margins and distally on lateral side near ventral margin, and 3 spinous bristles (1 dorsal, 1 ventral, 1 lateral). 3rd joint short with dorsal margin longer than ventral, with 3 bristles (1 ventral, 2 dorsal). 4th joint with 4 spinous bristles (3 ventral, 1 dorsal). Sensory bristle of 5th joint with about 5 short proximal and 5 longer terminal filaments. 6th joint fused to 5th, with small medial bristle. 7th joint: a-bristle about 3 times length of bristle of 6th joint, with short marginal spines; b-bristle about twice length of a-bristle, with 1 short proximal and 4 longer terminal filaments; c-bristle shorter than sensory bristle of 5th joint, with 6 short proximal and 5 longer terminal filaments. 8th joint: d- and e-bristles same length as sensory bristle of 5th joint, bare with blunt tips; f-bristle shorter than c-bristle, with 5 short proximal and 5 longer terminal filaments; g-bristle same length as bristle of 5th joint, with 3 short proximal and 5 longer terminal filaments.
Second Antenna: Protopodite with rows of medial spines near midlength. Endopodite 3-jointed: 1st joint short with 5 small bare bristles; 2nd joint elongate with 1 long spinous bristle and 2 short bristles with terminal spine; 3rd joint elongate with 3 bristles (1 proximal, 2 terminal) with terminal spine. Exopodite: 1st joint with minute, straight, tubular, medial bristle; bristles of joints 2-8 slightly longer than combined lengths of joints 2-8, bare, each with minute talon-like tip; 9th joint with 6 bristles (3 shortest form dorsal group and bear short marginal spines; 3 longer bristles terminal, bare or with few distal ventral spines and talon-like tips); joints 2-8 with terminal rows of short and long spines.
Mandible: Coxale endite deeply bifurcate, spinous, with minute ringed bristle near base. Basale: medial surface with rows of spines and long hairs, 5 proximal bristles (3 stout pectinate, 2 short slender spinous ringed), and 1 longer bristle (with long proximal and short distal spines) at midlength; 6 bristles (with long proximal and short distal spines) on or near ventral margin (terminal bristle longest); lateral surface with proximal spines; dorsal margin with 3 bristles (1 near midlength, 2 subterminal). Exopodite about same length as dorsal margin of 1st endopodial joint, with hirsute distal pad and 2 subterminal bristles (proximal bristle longer, with long spines near midlength; distal short bristle with indistinct short marginal spines). 1st endopodial joint with 4 spinous ventral bristles (3 long, 1 short), and row of spines along distal dorsal corner. 2nd endopodial joint: medial surface with proximal rows of spines; ventral margin with distal spinous bristles forming 2 groups (proximal with 3 bristles; distal with 2 or 3); dorsal margin with spinous bristles forming 2 closely spaced groups (proximal with 3 bristles; distal with 7 longer bristles). 3rd endopodial joint with 2 claws (dorsal claw short) and 3 ringed bristles (an oval "socket" proximal to base of terminal claw on both limbs of USNM 194008 probably indicates a missing medial claw). (Rings and spines of bristles not always shown.)
Maxilla: Coxale with dorsal fringe and long dorsal bristle with long proximal hairs and short distal spines. Endite I broad with 10 spinous and pectinate bristles (endite II narrow, with 5 spinous and pectinate bristles; endite III long narrow, hirsute, with 10 spinous and pectinate bristles; 1 additional long proximal bristle (with short spines) on either endite II or III. Basale with 3 long spinous bristles (2 ventral, 1 dorsal). Exopodite short with 3 bristles (proximal short with short spines, 2 terminal long with long proximal and short distal spines). 1st endopodial joint with spines along anterior margin, 1 long alpha-bristle and 4 beta-bristles. 2nd endopodial joint with 3 slender a-bristles, 2 b-bristles (anterior ringed, posterior claw-like), 2 ringed c-bristles, and 3 d-bristles (2 anterior claw-like, posterior bristle-like ringed).
Fifth Limb: Endites I and II each with 6 or 7 spinous bristles; endite III with about 10 spinous bristles. 1st exopodial joint: main tooth with 4 pectinate teeth (distal tooth largest and with large anterior triangular cusp); spinous ringed bristle proximal to main tooth; anterior side of joint with 2 long bristles at midwidth and 1 smaller spinous bristle as well as stout spines on lobe at outer corner. 2nd exopodial joint: large flat triangular with 2 small cusps on inner edge; posterior side with stout c-bristle and row of 3 bristles (1 small bristle on each side of stout bristle). Inner lobe of 3rd exopodial joint with 3 bristles (bare or with minute spines); outer lobe with 2 bristles with long hairs. Fused 4th and 5th exopodial joints with total of 6 spinous bristles.
Sixth Limb: With 3 short epipodial bristles with long proximal hairs. Endite I with 2 short plumose medial and 1 long terminal bristle with wreaths of long spines; endite II with 1 spinous medial and 3 long spinous terminal bristles; endite III with 1 spinous medial and 7 or 8 spinous terminal bristles; endite IV with 1 spinous medial and 7 spinous terminal bristles. End joint with 12 or 13 spinous and hirsute bristles (include 2 slender bristles with long proximal and short distal spines on distal posterior edge of joint (bristles of this type not previously reported on posterior edge of Philomedidae)).
Seventh Limb: Proximal group with 4 bristles (2 on each side) of similar length, each with 2 or 3 bells; terminal group with 5 bristles (2 on comb side, each with 3 or 4 bells; 3 on peg side, each with 2-4 bells), some with few distal spines; short bristles slightly bulbous proximally (juvenile character). Terminus with comb of about 14 short alate teeth opposite 2 pegs with rounded tips.
Furca: Each lamella with 9 articulated claws decreasing in length and width posteriorly along lamella; all claws with stout teeth along posterior edge; claw 1 with posterior teeth 2-6 stouter than teeth 1, 7-10, and with row of stout medial teeth; claws 7-9 with small teeth along anterior edge; claws 1-8 with row of very long medial hairs near base; long spines present on edge of lamella after last claw; anterior edge of right lamella with distal spines.
Bellonci Organ: Short bare with minute triangular process at tip.
Eyes: Medial eye small with dark brown pigment. Lateral eye larger than medial eye with numerous small amber-colored cells.
Upper Lip: Conical with minute process on anterior tip, hirsute.
Genitalia: Not developed.
Posterior of Body: Posterior with rows of hairs and spines; posterodorsal comer with row of spines. Y-Sclerite: Unbranched with broad club-like anterior end.
DESCRIPTION OF ADULT FEMALE.—Carapacesimilar in shape and ornamentation to that of A-l male.
Infold: Infold of rostrum with 17 bristles parallel to anterior edge and 2 additional bristles on ventral edge near incisur. Remainder of infold not examined.
Selvage and Central Adductor Muscle Attachments: Similar to those of A-l male.
Carapace Size (length, height in mm): Slope 6: holotype and paratype, 1.74, 1.18.
First Antenna: Joints 1-6 similar to those of A-l male. C-bristle of 7th joint about same length as f-bristle of 8th joint, and both only slightly shorter than g-bristle of 8th joint; g-bristle same length as sensory bristle of 5th joint; filaments of bristle of 5th joint and bristles of 7th and 8th joints not counted but appear similar to those of A-l male.
Second Antenna: Protopodite similar to that of A-l male. Endopodite 2-jointed: 1st joint short, with 5 slender bare bristles; 2nd joint elongate, tapering distally, with long spinous ventral and short bare terminal bristle. Exopodite: 1st joint with minute, straight, tubular, medial terminal bristle; bristles of joints 2-5 about same length as combined joints 2-8, bare, each with minute talon-like tip (tip broken off on most bristles); bristles of joints 6-8 broken, without spines or hairs on remaining part; 9th joint with 7 bristles (4 shortest with short spines form dorsal group; 3 longer bristles broken, without spines or hairs on remaining part); most joints without usual row of terminal spines.
Mandible: Coxale endite, exopodite, and 1st endopodial joint similar to those of A-l male. Basale with 7 bristles on or near ventral margin, otherwise similar to that of A-l male. 2nd endopodial joint: dorsal margin with 4 bristles in proximal group and 6 longer bristles in distal group; ventral margin with 3 spinous bristles in both proximal and distal groups; medial surface with spines. 3rd endopodial joint with 3 claws (dorsal claw 1/4 to l/2 length of longest claw; medial claw about 3/4 length of lateral claw) and 3 bristles.
Maxilla: Coxale, basale, exopodite, and 1st endopodial joint similar to those of A-l male. Endites similar to those of A-l male except endite II with 6 bristles. Bristles of 2nd endopodial joint obscured.
Fifth Limb: Endites with about same number of bristles as on A-l male. Exopodite similar to that of A-l male.
Sixth Limb: Epipodite and endites similar to those of A-l male. End joint with 16 bristles including 3 slender bristles (with long thin hairs at midlength) along posterior edge dorsal to the 2 stout plumose bristles on posteroventral corner, shape of end joint similar to that of A-l male.
Seventh Limb: Proximal group with 4 bristles (2 on each side) of similar length, each with 4 bells. Terminal group with 5 bristles (2 or 3 on comb side, each with 3-5 bells; 2 or 3 on peg side, each with 3-5 bells), some with indistinct distal spines. Comb and pegs similar to those of A-l male.
Furca: Paratype from Slope 6 with 9 claws on right lamella and 10 on left; claws and lamellae, in general, similar to those of A-l male.
Bellonci Organ: Similar to that of A-l male except minute triangular terminal process absent
Eyes: Medial eye similar to that of A-l male. Lateral eyes absent
Upper Lip, Posterior of Body, and YSclerite: Similar to those of A-l male.
Genitalia: Small oval on each side of body anterior to furca.
Number of Eggs: Paratype from Slope 1 with 5 eggs in marsupium (length of typical egg 0.42 mm).
Behavior: Long bristles of joints 6-9 of the exopodite of the 2nd antenna of the ovigerous paratype from Slope 6 as well as the holotype (adult female without eggs in marsupium) are broken, indicating that those females are no longer capable of swimming. Broken bristles have been reported previously on other genera of the Philomedidae (Komicker, 1975:74), but not on Igene. Natatory hairs are absent on exopodial bristles of adult females of I. walleni and I. bryx but no bristles are broken. The broken bristles of the female I. illex suggest that the missing parts have natatory hairs.
COMPARISONS.—The carapace of I. bryx differs from that of I. illex in having a projecting caudal process. The 2nd endopodial joint of the female 2nd antenna of I. illex differs from those of I. walleni and I. curtus in having a terminal bristle; the terminal bristle of I. illex is much longer than that of I. bryx. The 7th limbs of I. illex differ from those of I. curtus and I. walleni in having more comb teeth and terminal pegs. The Y-sclerite is unknown for I. curtus, but on I. walleni and I. bryx the sclerite is branched; whereas it is unbranched with a broad anterior end on I. illex. The posterior margin of the end joint of the 6th limb of I. illex bears 2 or 3 slender bristles dorsal to the 2 stout plumose bristles on the posteroventral comer; these have not been reported on previously described species of Philomedidae. The male I. illex has lateral eyes; they are absent on I. walleni and I. bryx, which are from much deeper water, the male is unknown for I. curtus.
REMARKS.—The Y-sclerite of I. illex resembles that of species of Zeugophilomedes Kornicker, 1983b:478. The distribution of the furcal claws of I. illex clearly shows that the species should not be referred to Zeugophilomedes. Species of Tetragonodon Brady and Norman, 1896:667, as revised by Kornicker (1989:82), also have an unbranched Y-sclerite, but unlike that of I. illex, it is slender and without a broad tip. Igene illex is referred to the Philomedinae rather than the Pseudophilomedinae because of the backward projecting end joint of the 6th limb; however, without knowledge of the morphology of the sensory bristle of the 5th joint of the 1st antenna of the adult male, the referral cannot be made with certainty. The unusual Y-sclerite of I. illex may warrent proposal of a new genus for species of Philomedinae having the club-like sclerite and a furca having no secondary claws between primary claws.”
(Kornicker, 1995, pp. 3-8)
