AMERICAN MUSEUM No Vitates PUBLISHED by the AMERICAN MUSEUM of NATURAL HISTORY CENTRAL PARK WEST at 79TH STREET, NEW YORK, N.Y
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AMERICAN MUSEUM No vitates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3102, 33 pp., 10 figures June 24, 1994 A New Genus for South American Snakes Related to Rhadinaea obtusa Cope (Colubridae) and Resurrection of Taeniophallus Cope for the "Rhadinaea" brevirostris Group CHARLES W. MYERS' AND JOHN E. CADLE2 CONTENTS Abstract ........................................................ 2 Introduction .................................................... 2 Taeniophallus Cope, 1895 ........................................ 4 Discussion .................................................... 4 Psomophis, new genus ............................................ 6 Description ................................................... 7 Osteology ................................................... 7 Hemipenes .................................................. 9 Discussion .................................................... 12 Unusual Hemipenes ......................................... 12 A Premaxillary Modification .................................. 14 Synopses of Species .............................................. 16 Key to Species ................................................. 16 Psomophis genimaculatus (Boettger) ............................. 16 Psomophis joberti (Sauvage) ..................................... 20 Psomophis obtusus (Cope) ...................................... 23 ' Chairman and Curator, Department of Herpetology and Ichthyology, American Museum of Natural History. 2 Academy of Natural Sciences of Philadelphia; presently Associate Curator and Associate Professor of Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA. Copyright © American Museum of Natural History 1994 ISSN 0003-0082 / Price $3.40 2 AMERICAN MUSEUM NOVITATES NO. 3102 Relationships of Psomophis ................ ........................... 26 Acknowledgments ........................................... 29 Appendix: Museum Abbreviations and Locality Records ......... .................. 29 References ........................................... 30 ABSTRACT Psomophis, new genus, is erected to accom- The species of Psomophis are most likely to be modate three species of South American colubrid confused with species of the "Rhadinaea" brevi- snakes: Rhadinaea obtusa Cope, 1863 (type spe- rostris group (sensu Myers). Possible relationships cies), Enicognathus joberti Sauvage, 1884, and of the brevirostris group to the "Liophis" or Liophisgenimaculata Boettger, 1885. The last spe- "Rhadinaea" undulata group (i.e., Echinanthera cies is here resurrected from the synonymy ofjob- Cope, sensu stricto) remain to be investigated, in- erti. These snakes differ from all other South asmuch as a recent claim of hemipenial synapo- American colubrid genera in the combined char- morphy cannot be corroborated. Rediscovery of acters ofsmall size, high number ofventral scales, Lygophis nicagus-nominal type species ofthe un- midbody scale rows 17 or 19 with lateral reduction used name Taeniophallus Cope-allows, for pres- posteriorly, distinctively shaped premaxillary bone, ent purposes, convenient resurrection of Taenio- and peculiar hemipenis. phallus for the brevirostris group. The new genus The hemipenis is deeply bilobed, lacking apical Psomophis differs in fundamental hemipenial and discs, with the lobes individually capitate (bicap- other characters from Echinanthera and Taenio- itate) and pseudocalyculate (becoming acalyculate phallus. upon eversion); the lobes bear large spinulate pa- Reasons are footnoted for a few incidental tax- pillae (soft spines) on the sulcate sides but are nude onomic conclusions on Neotropical xenodontines, on the asulcate sides; the organ is spinose proximal including (1) suggested removal ofPliocercus (cor- to the lobes; the sulcus spermaticus is deeply forked al snake mimics) from the synonymy of Urotheca, and centrolineal. Psomophis probably is allied with an apparently monophyletic sister group, and (2) a large group of South American "xenodontine" removal ofthe genera Saphenophis and Tropidod- colubrids, but relationships among most genera ryas from the tribe Pseudoboini, which is returned within that assemblage are presently unclear. to Bailey's 1967 concept. INTRODUCTION The Neotropical snake genera Rhadinaea cies-genimaculata Boettger (=joberti Sauvage), ob- and Liophis historically have accommodated tusa Cope, and steinbachi Boulenger-are under in- many species ofrelatively generalized terres- vestigation and can conveniently (but improperly) be included in the genus Liophis, where they also have trial colubrids. They are among the largest been placed by various authors. Also in this category genera of Neotropical colubrids, each with is "Liophis" undulatus and its several relatives, which more than 30 recognized species according comprise an undescribed genus according to Joseph to recent revisions (Myers, 1974; Dixon, R. Bailey (personal commun.), who has data on the 1980). Myers (1969, 1973) had provisionally group. transferred several species previously as- Dixon (1980) necessarily referred the above signed to these and other genera to Lygophis species to incertae sedis during his process of (= Liophis sensu Dixon) before erecting the redefining Liophis. Since then, Di-Bernardo genus Saphenophis to hold them. Myers (1992) has properly resurrected Echinanthera (1974: 22) similarly excluded several other Cope for the undulatus group (but see below), enigmatic species from Rhadinaea by trans- and Myers and McDowell (in manuscript) ferring them temporarily to Liophis, which have clarified the relationships of "Rhadi- was taxonomically confused anyway: naea" steinbachi. Certain species that have been referred to Rhadi- Since 1974, it has seemed evident that the naea by other authors actually are not assignable to remaining epithets mentioned above-geni- any genus as presently defined. Three of these spe- maculata,joberti, and obtusa -belong to spe- 1 994 MYERS AND CADLE: SOUTH AMERICAN SNAKES 3 cies in a small monophyletic group in need which therefore is not a "new" genus4 as of a new generic name. There was uncertain- thought by Bailey (vide supra)-we disagree ty, however, over the interpretation of par- with Di-Bemardo's stated reasons for includ- ticular hemipenial features based solely on ing the "Rhadinaea" brevirostris group with- dissection ofretracted organs. But an everted in a resurrected Echinanthera (see below, Re- hemipenis is finally available and a generic marks under Taeniophallus). Therefore, we name and synopsis of the species are pre- shall use the name Echinanthera in its strict sented herewith. sense, that is, for the nominal species that Some of the nomenclatural changes re- seem closely related to the generic type (Apo- ferred to above require us to be explicit about rophis cyanopleurus Cope), including E. usage of generic names. We use Liophis in amoena, E. cyanopleura, E. melanostigma, the sense of Dixon (1980) and Myers (1986), and E. undulata. as the plesiomorphic member ofthe tribe Xe- nodontini. Unless qualified by "s.l." (sensu Nonetheless, the brevirostris group should lato), we currently use the name Rhadinaea not be maintained in Rhadinaea. Myers in a revised sense to refer to all species of (1974: 232, 236) stated that, Rhadinaea sensu Myers (1974) except for the eight Central and South American species of the taxonomic position ofthe brevirostris group should Myers' lateristriga group3 and the six South be re-evaluated as data become available on the sys- American species of his brevirostris group. tematics ofother groups ofSouth American colubrids There is potential confusion between spe- ... The possibility should also be kept in mind that the brevirostris group might have been independently cies of the new genus and members of the evolved from alsophiine ancestry-although reason- "Rhadinaea" brevirostris group, which was ably conclusive evidence should be presented by any- placed in Echinanthera by Di-Bernardo one wishing to remove that group from Rhadinaea. (1992). Although we have been aware for some time that Echinanthera is an available Support for removal of the brevirostris name for the "Liophis" undulatus group- group from Rhadinaea subsequently was pro- vided by Cadle (1984a, 1984b), whose im- 3 The Rhadinaea lateristriga group = Urotheca sensu munological studies ofserum albumins dem- stricto, an assemblage of curiously patterned xenodon- onstrated that the large assemblage commonly tines that share hemipenial and caudal resemblances (now referred to as xenodontines consists princi- perceived as synapomorphies) with vividly ringed coral pally oftwo large Neotropical clades, one pri- snake mimics ofthe genus Pliocercus (Myers, 1974: 230, marily Central American, the other South 233; Savage and Crother, 1989). Although Savage and American. Moreover, those data suggested Crother (op. cit.) properly addressed one ofthe problems substantial evolutionary and temporal diver- of paraphyly in Myers' revision of Rhadinaea, we dis- gence between members of the two clades agree with their submerging of Pliocercus in the synon- (Cadle, 1 984c, 1985). With respect to Rhad- ymy of Urotheca. Present evidence suggests that Pliocercus and Urotheca inaea, the immunological data demonstrated s.s. are monophyletic sister groups-each of which is a clear association of most species with the characterized by synapomorphies of color pattern, in- cluding Micrurus-like rings in the former and a longi- tudinal white line(s) in