"Thaumatoconcha sandersi, new species FIGURES 11i, 12g, 13e, I8a-c, 59-62
HOLOTYPE—USNM 143793, adult male, appendages on slides, carapace and some appendages in alcohol.
TYPE-LOCALITY—USNS Eltanin, Cruise 4, station 135, 62°40'S, 64°06'W to 62°37/S, 63°57'W, Drake Passage, 3715-3752 m.
PARATYPES—USNM 127275, 7 specimens from type-locality (includes 1 adult male and 2 adult females); USNM 143752, 2 specimens (1 adult male, 1 adult female).
ETYMOLOGY—Species named for Dr. Howard L. Sanders.
OTHER LOCALITIES—USNM 143752 from USCGC Glacier, station 0023, 72°47'30"S, 30°28'18"W, Weddell Sea, 3658 m.
DIAGNOSIS—Surface smooth with 1-3 anteroventral ridges and straight anteroventral margin (specimens on hand decalcified); length of male 1.78 to 1.89 mm; dorsal margin of 3rd joint of 1st antenna longer than dorsal margin of 4th joint; endopodite of mandible with 1 dorsal bristle on 1st joint and 2 on 2nd joint; rod-shaped organ with rounded tip; anterior lobe of male copulatory organ with slender recurved terminal process.
DESCRIPTION OF ADULT MALE—Valves subround, height of anterior margin greater than posterior; straight anteroventral margin delimited by a dorsal and a ventral forward pointing short protuberance; anterodorsal margin broadly convex, merging with short gently curved dorsal margin at a point about one-third greatest length; posterior margin evenly rounded; ventral margin curving gently forward and downward to point in front of subcentral adductor muscle-scar, then curving upward to join anteroventral margin below protuberance; dorsal outline subelliptical, greatest width at approximate midlength; end outline subelliptical, greatest width slightly above midheight.
Ornamentation: Specimens decalcified; surface smooth; anteroventral surface with 1 to 3 thin ridges parallel to valve margin; protuberances smooth, relatively stout.
Adductor muscle-scar: Scar subcentrally located, subelliptical, greatest diameter trending towards posterior end of hinge; attachment ends consist of 9 subequal pie-shaped segments radially arranged.
Size: USNM 143793, length 1.78 mm, height 1.63 mm, USNM 127275E, length 1.89 mm, height 1.56 mm, USNM 143752B, length 1.78 mm, height 1.50 mm.
First antenna: Similar to that of T. radiata.
Second antenna: Exopodite with 8 joints; limb otherwise similar to that of T. radiata.
Mandible: Third endopodial joint with 6 bristles; limb otherwise similar to that of T. radiata.
Maxilla, 6th limb, furca, rod-shaped organ, lips, posterior of body: Similar to those of T. radiata.
Fifth limb: Ventral margin of 1st exopodial joint with 11 bristles; limb otherwise similar to that of T. radiata.
Copulatory organ: Anterior lobe with slender recurved terminal process.
DESCRIPTION OF ADULT FEMALE—Carapace similar to that of male but slightly larger.
Size: USNM 127275A, length 1.99 mm, height 1.67 mm; USNM 127275C, length 2.00 mm, height 1.69 mm, USNM 143752A, length 1.94 mm, height 1.65 mm.
First antenna: Similar to that of T. radiata.
Second antenna: Exopodite with 8 joints; limb otherwise similar to that of T. radiata.
Mandible, maxilla, 6th limb, 7th limb, furca, rod-shaped organ, lips, posterior of body: Similar to those of male.
Fifth limb: Ventral margin of 1st exopodial joint with 6 bristles; limb otherwise similar to that of male.
COMPARISONS—See Table 13." (Kornicker & Sohn 1976, p.83-85)
