A Review of the Eel Genera Leptenchelys and Muraenichthys, with the Description of a New Genus, Schismorhynchus , and a New Species, Muraenichthys cbilensis'

The echeline genus Leptencbelys is recognized as monotypic and differs markedly from M uraenich th ys. Scbism orbyncbus, genus novum, is erected for M uraenichth ys labialis Seale. The genus M uraenichthys contains 19 known species in the tropical, subtropical, and temperate Indo-Pacific Ocean. M. cbilensis, a new species showing affinities to southern Australian congeners, is the first known from the New World. The present distribution of Muraenichthys and of the closely related genera Schultzidia and Scbi smorbyncbas is perhaps explained by paleogeography, paleoclimatology, and adult habitat preferences. Muraenichthys species may be grouped by differences in posterior nostril condition, dentition, and head pore placement. The following changes in taxonomy are proposed : Leptenchelys pinnaceps Schultz = Callechelys melanotaenia Bleeker. M uraenichth ys tasmaniensis McCulloch and Scolencb elys tasmaniensis smithi Whitley = Muraenichth ys vermifo rmis Peters. M. ogilbyi Fowler = M. macropterus Bleeker. THE OPHICHTHID GENERA M uraenichthys and Leptencbelys currently comprise heterogeneous assemblages of elongate worm-eels, each generically assembled for lack of outstanding characters of specialization. Recent work by various authors has both clarified and confused these complex genera. Schultz and Woods (19 49) gave a key to the species of Muraenichthys and described two new species. Schultz et al. (1953) later separated Leptencbelys from M uraenichthys and described a new species, Leptench elys pinnaceps. My examination of the holotype of L. vermiformis Myers and Wade, 1941 (USNM 101785) , the genotype, has shown it to lack a median ventral snout groove and to possess low, unconstricted gill openings, in the latter character differing markedly from the species of M uraenichth ys. Examination of the paratype of Leptencb elys pinnaceps (USNM 202543) has shown the taxon to be a junior synonym of Callechelys m elanotaenia Bleeker, 1864. The remaining species previously referred to Lep1 Contribut ion from the Scripps Institution of Oceanography, Uni versity of California, San Diego . Revised manuscript received Febru ary 5, 1970. 2 Gr aduate D epartment , Scripps Inst itution of Oceanography , University of Californ ia, San D iego (La Jolla, California 92037 ). tencbelys, M uraenichth ys labialis Seale, 1917, is similar to species of M ttraenichthys but differs in' its grooved snout and elongate anterior nostrils. Until now, only tropical, subtropical, and temperate Indo-West Pacific species have properly been referred to M ttraenichth ys. The discovery of an undescribed species collected by the 1965 "Anton Bruun" expeditions in the offshore islands of Chile represents the first record of this speciose genus in the New World. Th e purposes of this review are : (a) to describe a new genus, Scbismorbyncus, (b) to provide a key to the identification of the species of Mttraenichthys and related genera, (c) to describe a new species, M . cbilensis, (d) to discuss the possible origins and the dispersal of M . cbilensis or its ancestral species to the New World, and (e) to clarify the species within M ttraenichthys and to discuss species omitted by or described since Schultz and Woods ( 1949). MATERIALS AND METHODS All measurements are straight-line measurements, made either with a 300-mm ruler with 0.5 mm gradations ( for standard length , trunk