“Metaschisma nex, new species
Figures 69-71, 111b
ETYMOLOGY.—From the Latin nex (violent death).
HOLOTYPE.—Undissected ovigerous female in collection of the Museum of Victoria.
TYPE LOCALITY.—Slope 1, 34°59.52'S, 151°5.94'E, New South Wales, off Nowra; depth 204 m.
PARATYPES.—Slope 1: USNM 193930, adult female on slide and in alcohol; USNM 193931, ovigerous female on slide and in alcohol; USNM 193932, A-l male on slide and in alcohol; 15 specimens (adult females (at least 1 ovigerous) plus late juveniles).
DISTRIBUTION.—Slope 1,204 m.
DESCRIPTION OF ADULT FEMALE.— Carapace oval in lateral view with broad rostrum and small indented incisur. Posterior margin without projecting caudal process.
Ornamentation: Surface reticulate with borders of reticulations formed by rows of minute spine-like papillae with pointed or blunt tips; papillae especially visible along valve edges. Bristles of 2 types present: 1, long slender bristles with triangular base; 2, more abundant shorter and stouter bristles, some tapering from base to tip, others with fairly parallel sides except for tapering tip; bristles with parallel sides longer near posterior margin.
Infold: Rostral infold with 11 or 12 long spinous bristles and 5-8 short thread-like bristles; paired bristles present at inner end of incisur. Anteroventral infold with 1 short bristle just ventral to inner end of incisur followed by space, 1 thin bristle, and 5 or 6 spinous bristles; about 9 striations parallel to valve edge in vicinity of bristles. Broad infold in posteroventral comer with about 10 short bare bristles either on or distal to list and several thread-like bristles proximal to list near inner margin of infold; a few additional bristles along list just anterior to posteroventral comer.
Selvage: Broad lamellar prolongation along anterior, anteroventral, and ventral margins with fringe of long and short filaments; many long filaments with thin marginal hairs; prolongation divided at inner end of incisur, prolongation narrower and without long filaments in immediate vicinity of posteroventral corner.
Central Adductor Muscle Attachments: Including about 11 ovoid attachments.
Carapace Size (length, height in mm): Slope 1: holotype, 1.49, 1.00; USNM 193930, 1.49, 1.02; USNM 193931, 1.47, 1.04; 2 unnumbered paratypes: 1.47, 0.99; 1.46,0.99.
First Antenna: 1 st joint bare. 2nd joint with ventral, dorsal, and medial spines, lateral spines along distal edge, and 3 spinous bristles (1 ventral, 1 dorsal, 1 lateral). 3rd joint with few short ventral and medial spines, numerous long dorsal and lateral hairs, and 2 short spinous bristles (1 ventral, 1 dorsal). 4th joint with ventral and dorsal hairs and 4 bristles (1 dorsal with short spines, 3 ventral with long and short spines). 5th joint with spines on distal corners, and long ventral bristle with 4 short proximal filaments and several short terminal filaments. 6th joint fused to 5th, with short spinous medial bristle. 7th joint: a-bristle about same length as bristle of 6th joint; b-bristle small, slightly shorter than a-bristle, with minute distal filament; c-bristle long, with 3 very small proximal filaments, 1 very short distal filament, and 4 short terminal filaments including stem; joint with row of lateral hairs (the hairs could be interpreted to be on 6th joint). 8th joint: d- and e-bristles about same length as c-bristle, bare with blunt tips; f-bristle about 3/4 length of c-bristle, with 1 minute distal filament and several minute terminal filaments; g-bristle about same length as bristle of 5th joint, slightly longer than c-bristle, with 2 minute proximal filaments, 1 minute distal filament, and several minute filaments at tip.
Second Antenna: Protopodite bare. Endopodite 2-jointed: 1st joint with 5 short bare proximal bristles and 1 spinous distal bristle of similar length; 2nd joint elongate with 1 long bristle (with long and short spines) at midlength, and 1 shorter terminal bristle with short spines. Exopodite: 1st joint with minute terminal medial tubular bristle; bristles of joints 2-5 short bare; on both limbs of USNM 193930 and 193931 bristles of joints 6-8 broken off near base, without spines or hairs on stumps; 9th joint with 6 or 7 bristles (4 stout, 2 or 3 short slender), all except a short slender bristle (on USNM 193931) broken off near base (1 slender bristle with short spines on stump, others without spines or hairs on stumps).
Mandible: Coxale with long spines near endite; endite bifurcate (tip of 1 prong broken off on USNM 193930), with long proximal spines and short distal teeth; minute peg between prongs. Basale: unusually short; medial side with few distal spines, 4 proximal bristles (2 stout unringed, 2 slender ringed spinous), 1 short, slender, ringed, spinous bristle at midlength, and 1 slender, ringed, spinous, distal bristle near ventral margin; ventral margin with 1 short, slender, ringed, spinous, proximal bristle; lateral side with long proximal hairs near ventral margin; dorsal margin with 1 short ringed bristle at distal 3/4, and 2 subterminal bristles (1 short ringed, 1 long ringed with few marginal hairs). Exopodite a minute node with single terminal bristle with few short spines. 1st endopodial joint: medial side with spines forming row along distal edge and 1 short spinous ringed distal bristle near ventral margin; ventral margin with spines, 2 minute ringed distal bristles with short marginal spines, and 1 short ringed bristle (missing on illustrated left limb of USNM 193930, interpreted to be broken off); dorsal margin with terminal row of short spines; broad internal promoter muscles extend from 1st joint to sclerite attached to ventral terminal corner of 3rd joint. 2nd endopodial joint short stout, tapering distally; dorsal margin with proximal spines and 6 short ringed spinous bristles at about midlength; medial surface with 2 short ringed spinous a-bristles near ventral margin; ventral margin with proximal spines and 1 stout claw-like b-bristle (with marginal teeth) distal to a-bristles, and 1 stout terminal claw-like c-bristle with marginal teeth; lateral side with few rows of spines and minute ringed terminal d-bristle near ventral margin. 3rd endopodial joint with 2 minute medial spine-like bristles at joint midlength, 3 short slender ringed a-bristles with bases medial to terminal claws, 1 fairly long pointed ventral b-bristle with 3-5 stout proximal ventral teeth and distal rings, and 1 long stout bare terminal claw-like c-bristle with right-angle bend near base, indistinct minute proximal ventral spines, and few transverse grooves or ridges near tip. (Letters used to designate bristles of 2nd and 3rd endopodial joints explained in Kornicker (1985a:2).)
Maxilla: Precoxale and coxale with dorsal fringe. Coxale with stout plumose dorsal bristle. Endite I broad spinous with 6 bristles (1 small, 3 claw-like, 2 long stout); endite II narrow with 5 bristles (3 slender spinous, 2 claw-like pectinate); endite III small with 3 bristles (1 or 2 claw-like). Basale with 2 slender spinous bristles (1 ventral). Exopodite represented by 2 stout plumose bristles with bases on slight rise, but without usual lobe. 1st endopodial joint with 1 spinous alpha-bristle and 1 spinous beta-bristle of similar length (joint folded in illustrated mounted limb of USNM 192930 and only stump of beta-bristle present). 2nd endopodial joint with 6 bristles (3 claw-like unringed pectinate, 3 shorter slender ringed spinous).
Fifth Limb: Endite I with 2 bristles; endite II with small triangular tooth and 2 bristles; endite III with small triangular tooth, 1 small unringed bristle (with 1 tooth) adjacent to triangular tooth, and 3 bristles (1 claw-like). 1st exopodial joint: with long fang-like tooth with 3-5 cusps (excluding tip of tooth) along distal inner edge; anterior side of joint with 1 short bristle at mid width of distal edge; posterior side of joint with 1 proximal bristle near inner edge of fang-like tooth. 2nd exopodial joint with 3 teeth along inner edge: distal tooth fang-like with 6-9 small pointed cusps along inner margin (limbs of USNM 193931 with row of 6 cusps on posterior side and row of 2 or 3 on anterior side); middle tooth with 5 pointed cusps along inner edge (including tip of tooth); proximal tooth with 3 or 4 pointed cusps along inner edge (including tip of tooth); posterior side of joint with long spinous bristle at midwidth. 3rd exopodial joint without inner lobe but with 1 spinous bristle in usual place of inner lobe (this could be interpreted to be on 2nd joint), and 2 stout bristles (with abundant long proximal hairs and short distal spines) on outer lobe. 4th and 5th exopodial joints fused hirsute, with total of 4 spinous and pectinate bristles (1 claw-like).
Sixth Limb: With 2 short plumose epipodial bristles. Endite I with 3 spinous bristles (2 short, 1 longer); endite II spinous, with 2 or 3 long spinous terminal bristles; endite III spinous, with 2 or 3 long spinous terminal bristles; endite IV spinous, with 2 long spinous terminal bristles. End joint spinous, with 10 bristles (posterior 3 plumose, remaining bristles with long proximal spines or hairs and short distal spines).
Seventh Limb: Proximal group with 4 cylindrical bristles, 2 on each side with distal spines and 1 or 2 minute bells; terminal segment with 4 cylindrical bristles (longer than those of proximal group), 2 on each side with distal spines and 2 or 3 minute bells. Terminus with comb of about 17 alate teeth opposite 2 pegs (longest peg with marginal spines).
Furca: Each lamella with 11 articulated claws; claws 1, 2, 4, 6 primary; most lateral teeth broken off primary claws of USNM 193930 except proximally and distally on claw 1, and proximally on claw 2 of left lamella; claw 1 with 3 large medial teeth in row; right lamella anterior to left by width of base of claw 1 and with few long spines along anterior edge; lamellae following claws with abundant long hairs.
Bellonci Organ: Elongate with weak suture at proximal 1/3; part distal to suture hirsute and tapers to point
Eyes: Lateral eye small, with brown pigment but no ommatidia. Medial eye larger man lateral eye, with brown pigment.
Upper Lip: Rounded with 2 minute anterior spines (no glandular processes observed).
Genitalia: Small amber-colored oval on each side of body anterior to furca.
Anterior of Body: 1 or 2 small rounded processes at midheight
Posterior of Body: Evenly rounded with spines ventral to midheight
Y-Sclerite: With ventral branch, and posterior end bent ventrally.
Eggs: Slope 1: holotype with 5 eggs in marsupium; USNM 193930 with 2 fairly large unextruded eggs on each side of body; USNM 193931 with 3 eggs in marsupium, length of typical egg 0.35 mm; unnumbered paratype with 6 eggs in marsupium.
DESCRIPTION OF A-l MALE.—Carapace similar in shape and ornamentation to that of adult female. Infold not examined.
Carapace Size (length, height in mm): USNM 193932 (valves slightly distorted) 1.33,0.84.
First Antenna: Joints with same number of bristles as on adult female. 7th joint: b-bristle distinct, ringed, about same length as a-bristle, with 3 filaments (1 small at midlength, 1 small at distal 3/4, and 1 minute subterminal).
Second Antenna: Protopodite bare. Endopodite 3-jointed: 1st joint with 4 or 5 short ventral bristles (3 or 4 proximal, 1 distal); 2nd joint elongate with 3 (1 long, 2 short) spinous ventral bristles; 3rd joint elongate with 1 slender dorsal bristle at 'A length and 2 short terminal bristles. Exopodite: 1st joint with minute terminal tubular medial bristle; bristles of joints 2-8 short bare; 9th joint with 6 bare bristles (3 short stout 1 short slender, 2 minute); joints 2-8 with row of minute spines along distal edge.
Mandible: Coxalc and basale similar to that of adult female. 1st endopodial joint: only 2 long bristles observed on or near ventral margin (2 small bristles present on adult female not observed, possibly obscured). 2nd endopodial joint: dorsal margin with 4 or 5 bristles; joint otherwise similar to mat of adult female. 3rd endopodial joint: ventral pointed b-bristle with 4 proximal ventral teeth; joint otherwise similar to that of adult female.
Maxilla: Similar to that of adult female.
Fifth Limb: Epipodite with 46 bristles. Limb similar to that of adult female.
Sixth Limb: With 2 epipodial bristles. Endites 1, II, and IV with 2 bristles; endite III with 3 bristles. End joint with 7 bristles.
Seventh Limb: Distribution of bristles similar to those of adult female but bristles tapered (juvenile character); all bristles with distal spines; proximal bristles with 1 or 2 bells, terminal bristles with 2 bells. Terminal comb with 11 teeth opposite 2 elongate curved pegs (inner peg longer spinous).
Furca: Each lamella with 10 claws; claws 1, 2, 4, and 6 primary claws.
Bellonci Organ: Similar to that of adult male but without suture.
Eyes: Medial eye similar to mat of adult female. Lateral eye about same size as medial eye, about twice size of lateral eye of adult female, with black pigment and many small cells, but no ommatidia apparent.”
(Kornicker, 1994, p.123-128)
