Astronesthes nigroides, a New Species of Stomiatoid Fish from the Eastern Pacific Ocean

Abstract

Holotype.-USNM 179754; collected July 18, 1958 at 38055.7'N, 137044.6'W, at a depth of 225 meters. Standard length 77.8 mm. This is the only known specimen. Comparative Diagnosis.-A species of Astronesthes with the anal origin directly below the end of the dorsal base; a barbel that is slightly shorter than the head and which has the terminal third slightly swollen; luminous material covering most of the operculum other than the preopercle; 14 dorsal rays; 15 anal rays; 10 IP photophores which bend outward only slightly at the pectoral base; 17 PV; 19 VAV; 15 OV; 20 VAL; and 13 AC photophores. In barbel structure, A. nigroides resembles only A. niger. In the presence of luminous material on the operculum, it resembles only A. cyaneus. In twelve meristic characters used here, it is within the range or no more than one integer away from the recorded extreme of nine characters for both A. niger and A. cyaneus. A. richardsoni (= A. filifer) and A. splendidus agree in as many characters, but the entire facies of these two species is different, the former having, among other differences, no terminal modification of the barbel, the latter a bulb with several small distal filaments. A. nigroides is compared with these four species in Table I. Description.-Depth of body nearly 6 in standard length; caudal peduncle depth less tha one-third of greatest body depth. Head 4.4 in standard length. Bony orbit 3.6 in head length, equal to snout. Upper jaw about five-sixths of head length. Premaxilla with two long, barbed fangs anteriorly, the second longest, and three groups of two small teeth; maxilla with 19 contiguous, pointed teeth, slanting backward, in a comblike series. Mandible with a tiny anterior tooth, followed by a large, barbed fang and then five groups of two or three small teeth, with a few tiny teeth between and lateral to them. A tooth