“Rheina relax Kornicker, new species
Figures 52-54
ETYMOLOGY.—From the Latin relax (loosen, slacken, unbend).
HOLOTYPE.—NMV J40009, undissected ovigerous female in alcohol.
TYPE LOCALITY.—Slope 85, 41°52.87'S, 148°37.93’E to 41°59.56'S, 148°31.13'E, Tasmania, 37 km NE of Cape Tourville, Freycinet Peninsula; collected in 3 m Isaac –Kidd midwater trawl sample that hit bottom; bottom depth 124-478 m. (Because only 1 species was collected (3 adult females plus 3 juveniles), it is likely that specimens came from the water column.)
PARATYPES.—Slope 21:1 partly dissected A-2 juvenile in alcohol (length 1.07 mm, height 0.70 mm); 1 undissected A-2 juvenile in alcohol. Slope 85: USNM 194017, adult female with choniostomatid copepods, on slide and in alcohol; USNM 194018, partly dissected ovigerous female with cryptoniscid isopod in alcohol; NMV J17675, 1 undissected ovigerous female with torn shell in alcohol, lost, and 3 undissected juveniles in alcohol.
DISTRIBUTION.—Slope 21, 220 m. Slope 85, 124-478 m (see "Type Locality" above for comments on depth).
DESCRIPTION OF ADULT FEMALE.— Carapace elongate; anterior edge of rostrum either straight or with slight concavity; posterior end truncate or with very slight concavity at dorsal end of caudal process.
Ornamentation: Carapace smooth but indistinct striations observed on some specimens just posterior to incisur.
Infold: Infold of rostrum with well-defined list with 6 or 7 bristles along anterior half and 1 longer bristle near posterior end; row of 9 bristles dorsal to rostral list and 1 small bristle posterior to row; 2 bristles near inner end of incisur and 1 bristle posterior to them; anteroventral infold and anterior 1/3 of ventral infold with row of about 30 closely spaced bristles; posterior 2/3 of ventral infold with row of about 16 widely spaced bristles; broad list of caudal process with row of 7-9 minute bristles near posterior edge; no bristles posterior to broad list. Right valve with long bar with posterior end just dorsal to broad list of caudal process and anterior end at posterior juncture of hinge.
Selvage: Lamellar prolongation of selvage broad and striate along lower margin of incisur, narrow and without striations elsewhere.
Central Adductor Muscle Attachments: About 18 oval attachments.
Carapace Size (length, height in mm): Slope 85: NMV J40009 (holotype), 1.36, 0.86, height 63% of length; USNM 194017, 1.67, 1.05, height 63% of length; USNM 194018, 1.57, 0.96, height 61% of length; NMV J17675, torn specimen length about 1.6. Length range 1.36-1.67; height range 0.86-1.05; range of height as percent of length 61-63.
First Antenna: 1st joint bare. 2nd joint spinous. 3rd joint short with indistinct medial spines and 2 spinous bristles (1 ventral, 1 dorsal). 4th joint with 2 spinous bristles (1 ventral, 1 dorsal). Sensory bristle of 5th joint with 8 long stout proximal filaments (only proximal part of most filaments shown), 3 shorter slender distal filaments, and bifurcate tip. 6th joint with short spinous medial bristle near dorsal margin. 7th joint: a-bristle longer than bristle of 6th joint, spinous; b-bristle about twice length of a-bristle, with 5 short proximal filaments; c-bristle with tip missing on both limbs of USNM 194017, remaining part longer than bristle of 5th joint, with 7 filaments (some with few spines). 8th joint: d-and e-bristles about twice length of b-bristle, bare with blunt tips; f-bristle long but with tip missing, 8 filaments (some with spines) on remaining part; g-bristle about 1/2 longer than bristle of 5th joint, with 10 filaments (some with spines) and bifurcate tip. (Only a- and b-bristles of 7th joint and no bristles of 8th joint shown.)
Second Antenna: Protopodite with short bare distal medial bristle. Endopodite 3-jointed: 1st joint with 4 proximal bristles (distal of these longer than others) and 1 short distal bristle; 2nd joint very long, bare; 3rd joint short with very long terminal filament. Exopodite: Joint 1 with few distal spines along dorsal margin; bristle of 2nd joint short, reaching 7th joint, ventral margin with 1 slender indistinct proximal spine and 7 stout pointed spines (spine 3rd from last longer than others); bristle of joint 3 long, with about 25 proximal ventral spines (proximal 14 of these fairly transparent), proximal dorsal hairs, and distal hairs on both margins; bristles of joints 4-8 long, with natatory hairs, no spines; 9th joint with 2 long bristles (dorsal of these shorter) with natatory hairs; joints 3-8 with small basal spines increasing in size on distal joints (spine of 8th joint about half length of 9th joint); 9th joint with lateral spine at distal dorsal corner (spine as long as joint); joints 2-8 with minute spines along distal edge; joint 2 also with few indistinct spines along ventral edge.
Mandible: Coxale endite spinous, bifurcate with 2 stout terminal prongs, with unringed bristle near base. Basale: Ventral margin with 2 small a-bristles, 1 small lateral b-bristle, 2 c-bristles, and 2 d-bristles (1 very long); dorsal margin with 3 bristles (1 at distal 2/3, 2 subterminal); medial surface with long spines in proximal ventral corner and short indistinct spines near dorsal edge. Exopodite about same length as dorsal margin of 1st endopodial joint, hirsute distally, with 2 distal ventral bristles (proximal bristle more than twice length of other). 1st endopodial joint with 4 ventral bristles (2 long, 1 short, 1 minute); distal dorsal corner of joint with row of spines. 2nd endopodial joint: Spinous ventral margin with 2 single and 2 paired bristles; medial of paired bristles unringed, stouter than other and with 5 stout dorsal teeth; dorsal margin with about 17 bristles (9 short cleaning bristles with long spines, 1 short bare bristle, and 7 long bristles) (bristles not shown); medial surface with rows of spines. 3rd endopodial joint with 1 slender dorsal claw, 2 stout claws at midwidth, and 3 bristles (longest lateral and with somewhat broader proximal part).
Maxilla: Endite I with 8 spinous bristles (some with spear-like tips and some with triaenid-type tips); endite II with 4 spinous bristles; endite III with 1 proximal bristle (could be interpreted to be on basale) and 5 terminal spinous bristles. Precoxale and coxale with dorsal hairs; coxale with stout hirsute dorsal bristle. Bristles of basale obscured on mounted limbs of USNM 194017, but left limb interpreted to have 2 bristles (1 long, 1 short) and right limb with 1 short bristle. Exopodite well developed, hirsute, with 1 plumose proximal bristle and 2 terminal bristles (middle plumose, other with indistinct short hairs). 1st endopodial joint; cutting tooth with 3 cusps; dorsal margin spinous, with 2 spinous alpha-bristles; ventral margin with 2 beta-bristles (medial bristle stout pectinate, lateral bristle shorter slender bare). 2nd endopodial joint with 3 a-bristles (inner 2 pectinate, outer bare), 2 spinous b-bristles (1 more than twice length of other), 2 pectinate c-bristles, and 3 pectinate d-bristles (posterior ringed, 2 others unringed, claw-like). (Right limb twisted.)
Fifth Limb: 3 endites with spinous and pectinate bristles. Protopodite with short lobate sclerotized anterior tooth. 1st exopodial joint: anterior side with row of 3 bristles (with long proximal hairs) plus 1 bristle with long proximal hairs closer to protopodial tooth; main tooth with smooth triangular proximal tooth and 6 pectinate teeth; bristle with long proximal hairs proximal to smooth tooth. 2nd exopodial joint: with 3 pectinate a-bristles (smallest bristle weakly ringed, others unringed), 6 ringed pectinate b-bristles (only 2 b-bristles shown), 1 stout c-bristle with long proximal and short distal spines, and 1 stout d-bristle with long proximal hairs. 3rd exopodial joint: Inner lobe with short proximal bristle with long proximal hairs, and 2 terminal bristles with short hairs; outer lobe hirsute, with 2 terminal bristles (outer with long proximal and short distal spines, inner with few indistinct short hairs). 4th and 5th exopodial joints fused, hirsute, each estimated joint with 2 bristles; short slender process with terminal spines present between estimated joints.
Sixth Limb: With 4 bare epipodial bristles. Endite I with 2 short medial and 1 long terminal bristle; endite II with either 1 short medial and 3 terminal bristles (middle bristle short, with base on medial side of edge), or 2 short medial and 2 long terminal bristles; endite III with 1 medial and 3 terminal bristles; endite IV with 1 medial and 2 terminal bristles; all endite bristles spinous. End joint with 7 anterior bristles (with 1 wreath of long proximal spines and short distal spines) followed by 1 bristle (with many long proximal and short distal spines) and 2 plumose bristles. Medial side of limb hirsute (not all hairs shown); lateral side of end joint with long stiff spines. Limb with brown pigment indicated by stippling in illustration.
Seventh Limb: Limb with 15-17 bristles: 2-4 proximal and 6 terminal on comb side; 4 proximal and 3 terminal on jaw side; bristles with 1-5 bells. Comb with 11 teeth (3 long teeth in middle, 2 shorter narrow teeth (with indistinct marginal spines) and 2 short broad flat-tipped teeth on each side); a short sclerotized prong with 3 minute teeth located along inner side of comb (detail in illustration). A sclerotized jaw with about 14 teeth (2 large and about 5 small along each edge) just proximal to inner bristles at base of comb.
Furca: Right lamella anterior to left by width of base of claw 1; each lamella with 9 claws; claw 3 slenderer than claw 4 but about same length; claws 2 and 4 nonarticulated; all claws with teeth along posterior margins. (Illustrated furca with most claws broken.)
Bellonci Organ: Short, cylindrical, with triangular tip with small terminal process.
Eyes: Medial eye small, bare, with brown pigment (stippled). Lateral eye large, about 3 times size of medial eye, with about 24 ommatidia and brown pigment (stippled) between ommatidia.
Upper Lip: Anteroventral unpaired part with fairly large glandular processes; paired tusks well developed, each with proximal pedestal, 3 or 4 glandular openings near tip, and with long hairs along anterior and posterior edges; posterior lobes of lip evenly rounded, hirsute.
Genitalia: Unusually large lobe with attached spermatophore on each side of body just anterior to furca.
Anterior of Body: With rounded anterior process between medial eye and upper lip.
Posterior of Body: Evenly rounded, bare.
Y-Sclerite: Typical for subfamily.
Eggs: Holotype with 8 eggs in marsupium, length of typical egg 0.29 mm; USNM 194018 with 8 eggs (length of typical egg including transparent vellum 0.31 mm; length without vellum 0.28 mm); NMV J17675, torn specimen with 1 egg in marsupium (some may have been lost), length with vellum 0.33 mm, length without vellum, 0.27 mm.
Parasites: USNM 194017 with choniostomatid copepods in marsupium: 1 female, 1 copepodite, and 14 egg sacs (some egg sacs with fairly well-developed copepodites, others with round eggs); USNM 194018 with 1 male or juvenile cryptoniscid isopod within ostracode carapace (ventral side of isopod adjacent to ventral part of body of ostracode; anterior end of isopod pointing anteriorly).
COMPARISONS.—Rheina relax differs from R. prex in having a lateral eye, in having both claws 2 and 4 of furca unarticulated, in having a jaw on the 7th limb, and in having only 2 bristles on the 9th exopodial joint of the 2nd antenna.”
(Kornicker & Poore, 1996, p.95-100)