Neotanais persephone, a New Species of Hadal Tanaidacean (Crustacea: Peracarida)

Neotanais persephone, a new species of tanaidacean and the first reported from the Puerto Rico Trench, is described and figured. The material represents the greatest depth record for the order from the Atlantic Ocean and for the genus worldwide. The species is placed within the american us group of species and is most similar to N. hadalis Wolff. Rudimentary oostegites are present on several copulatory males. In the course of faunal investigations of the tropical Atlantic Ocean, the research vessels JOHNELLIOTTPILLSBURYand JAMES M. GILLISS of the University of Miami's Rosenstiel School of Marine and Atmospheric Science occupied 30 bottom stations at depths greater than 6,000 ill in the Puerto Rico Trench. Tanaidaceans, all belonging to a new species of Neotanais, were collected at nine of these stations. This material includes the deepest confirmed records of any known member of the genus (but see bathymetric distribution below). The recent publication of a monograph on the Neotanaidae (Gardiner, 1975) allows these specimens to be placed properly in the family. They are described below. It is my intention to follow this brief report with a fuller account of the species, particularly with regard to the unusual combination of secondary sexual characteristics displayed by some of the specimens. In the following description, length to width and width to length ratios are abbreviated LW and WL, respectively. Depths in meters are corrected for sound velocity using Matthews' tables (Matthews, 1939). In the diagnoses, especially important characters are preceded by an asterisk (* ) . Characters shared by copulatory males and other instars are preceded by a dagger (t). Terminology follows that of Gardiner (1975). Neotanais persephone new species Figures 1-5 Material examined.-PILLSBURY Sta. 1166, 19° 47'N, 66° 17.5'W, 8,005 m, 10-ft Blake trawl, 20 January 1970; 4 juveniles (one with what may be very weak t gonopore rudiments and another unusually large-19.4 mm), 3 P ~ 1, 1 P ~ 2, 3 P t, 1 Cop t, fragments of 2 (not Cop t ).-PILLSBURY Sta. 1168, 19°42.5'N, 67°05'W, 8,381 m, 40-ft otter trawl, 21 January 1970; 1 P~2, 1 Pt, 9 Copt (six of these with rudimentary oostegites and one represented only by fragments of carapace and pereonite 2).-PILLSBURY Sta. 1380, 19°37.7'N, 65°04.0'W, 7,709-7,732 m, 40-ft otter trawl, 4 July 1971; 3 juveniles (of which 2 may be P t').PILLSBURYSta. 1382, 19°16'N, 65°50.7'W, 7,6227,714 m, 40-ft otter trawl, 5 July 1971; 2 juveniles (one is large enough to be P t -17.7 mm'), 1 P ~ 1. -PILLSBURY Sta. 1384, 19°45'N, 67°00'W, 8,3208,360 m, 40-ft otter trawl, 6 July 1971; 2 juveniles. -PILLSBURY Sta. 1406, 19°31.8'N, 68°07.5'W, 8,245-8,320 m, 40-ft otter trawl, 16-17 July 1971; 12 juveniles (one with what may be very weak t gonopore rudiments), 5 P~l, 1 P~2 (holotype), 1 Pt, 1 Copt (allotype).-GILLIss Sta. 56, 19°38'N, 68°00'W, 7,781-8,343 m, 40-ft otter trawl, 16-17 January 1973; 2 juveniles (of which one may be Pt'), 1 P~2, 1 Copt, 1 fragment (not Cop t ).-GILLISS Sta. 59, 19°22.9'N, 66° 50.0'W, 7,820-7,860 m, 40-ft otter trawl, 18 January 1973; 1 juvenile.-GILLIss Sta. 113, 19°26'N, 66°25.1'W, 8,016-8,027 m, 40-ft otter trawl, 14 July 1975; 1 P ~ 1. Diagnosis.-Neotanais belonging to the americanus group of species (Gardiner, 1975:43-44 ). Stages other than copulatory male. *tPereonite 6 always and *pereonites 1 The material for PII.LSRURY 1380, 1382, 1384 and Oll.L1SS 56, 59 was preserved in Bouin's fixative. As a result, the specimens have completely decalcified and thc <1 gonopore rudimcnts, if present, arc invisible.