Australasian Journal of Herpetology 1 Australasian Journal of Herpetology 6 (2009):1-21. ISSN 1836-5698 (Print) ISSN 1836-5779 (Online) A reclassification of the Rattlesnakes; species formerly exclusively referred to the Genera Crotalus and Sistrurus. Raymond Hoser 488 Park Road, Park Orchards, Victoria, 3114, Australia. Phone: +61 3 9812 3322 Fax: 9812 3355 E-mail: [email protected] Submitted 24 February 2009, Accepted 1 March 2009, Published 9 March 2009. ABSTRACT In spite of the fact that the taxonomy of most rattlesnakes at the species level has been established for many years, the genus Crotalus as referred to by most taxonomists up to 2008 failed to properly distinguish relationships within the group commonly defined as “rattlesnakes”. The genera Crotalus and Sistrurus (the latter sometimes subsumed in whole or part within Crotalus) as defined by most authors also fails to properly delineate relationships between taxa and fails to account for the modern definition and use of the “genus” level in terms of grouping closely related species only. This paper principally redefines the rattlesnakes at both genus and subgenus levels, formally naming a number of well-recognised species and species groups at the genus level for the first time. In summary rattlesnakes are subdivided into nine genera for which names were previously available for a total of five. For the other four genera, they are formally defined, diagnosed and named for the first time. A further seven well-defined subgenera are also defined and named for the first time. Later workers may choose to elevate some or all of these to full genus level. Keywords: new taxa, snake, rattlesnake, taxonomy, Crotalus, Sistrurus, Piersonus, Matteoea, Cummingea, Hoserea, Caudisona, Aechmophrys, Uropsophus, Cottonus, Smythus, Pillotus, Sayersus, Mullinsus, Edwardsus, Crutchfieldus. INTRODUCTION overlooked taxa have been formally named since Rattlesnakes are among the most well-studied Klauber’s seminal 1972 work, with the bulk of new serpents in the world. For a detailed appraisal of work (post 2000) involved in resolving the specific these snakes, see for example Gloyd (1940), status of snakes referred to at the subspecies level Klauber (1972), McDiarmid (1999), Schuett, et. al. for some time prior, largely through the use of new (2002), Campbell and Lamar (2004) and the many molecular methods. sources cited therein and other more recent Newly named taxa based on apparently previously publications that are readily available. unseen rattlesnakes include: Crotalus lannomi Both predating and postdating those major Tanner, 1966, C. tancitarensis Alvarado-Diaz and publications there has been the inevitable disputes Campbell, 2004 and C. ericsmithi Campbell and among herpetologists in terms of the status of given Villela 2008, but even these distinct new species populations in terms of their species, or subspecies have close affinities with other earlier named status (see examples below). (species-level) taxa as seen in their generic and However only a handful of new hitherto unknown or subgeneric placements below and would in the Hoser 2009 - Australasian Journal of Herpetology 6:1-21 Hoser 2009 - Available online at www.herp.net Copyright- Kotabi Publishing - All rights reserved 2 Australasian Journal of Herpetology absence of contrary evidence readily key out to I deferred splitting or naming further subgenera for other species within their assigned genus or distinct taxa such as “C. cerastes” (from other/s), subgenus and not another. pending further research by myself or others. (For the above trio of species taxa, lannomi and Some of the herein named subgenera may be ericsmithi to Matteoa gen. nov. and tancitarensis to elevated by other herpetologists to the rank of full Cottonus subgen. nov.). genus. As mentioned, other taxa first described as All are named here either by resurrection of subspecies have been elevated to full species available names or the designation of new ones. ranking or relegated to synonymy based on a Numerous phylogeny’s have been published, number of detailed studies, including molecular. including by Klauber 1972 and more recently several Some of these studies (post 1990) and results have by Murphy et. al. 2002 and others, including those been ignored for the purposes of this paper pending cited already. further confirmation of the results by other The relationships between the species as indicated herpetologists. by the authors have been broadly consistent in spite Most authors have referred to the rattlers with of various means used to derive their results. (usually nine) large plates on the crown of the head Newly described species (post 1990) derived from to the genus Sistrurus. This is often touted as a the splitting of species into more than one, generally “primitive form”, with the rest being assigned to the in accordance with subspecies designations, are catch-all genus Crotalus. obviously (and in the absence of evidence to the Within the generally recognised genus Sistrurus, contrary) to be placed in the same genus or one of the three species, S. ravus is regarded by subgenus, even if not recognised or mentioned in most authors as quite separate from the other two the text of this paper. (e.g. Knight, et. al. 1993, McCranie 1988), with Molecular methods are currently being used to recent papers sometimes reassigning the taxon to identify new species on a regular basis and so it is “Crotalus” (e.g. Bryson, 2007, Valencia Hernandez obvious that the species list/s within this paper will et. al. 2007). not be complete. This itself creates further problems in that in too The results of Murphy et. al. 2002, using molecular many ways the taxon has affinities with other data to identify groups of rattlesnakes by Sistrurus. relationships broadly accord with those of Klauber In reality the only sensible options are to subsume 1972 who at the time was relying on virtually Sistrurus within Crotalus (as in to “lump”) or everything but molecular data. alternatively to create a new genus for the taxon. Where the results differ, the main cause appears to In line with the above and as the placement of ravus be a lack of information or data, especially in the in Crotalus isn’t in accordance with all the evidence, case of early conclusions by Klauber (1972 or it is herein placed in a new formally named genus of earlier), shown to be in error by later authors. it’s own, namely Piersonus gen. nov. Most of Klauber’s errors related to rarer or little Within the genus Crotalus as recognised to 2008, known taxa for which Klauber had little if any access there are numerous distinct subgroups which should to specimens. be recognised as genera in their own right, including The purpose of this paper is not to voluminously for example the so-called atrox group, the so-called rehash the detail of these earlier studies, including long-tailed rattlers and others. all the intricate details of their studies and the Authors who have tackled the problem of grouping results. rattlesnakes into their most obvious subgroups This paper does not by any means seek to rehash include: Gloyd (1940), Klauber (1956) and again in the general knowledge base for rattlesnakes or for (1972), Brattstrom (1964) and Foote and MacMahon that matter provide elaborate descriptions of taxa (1977) all as detailed and summarized in Murphy et. beyond that deemed necessary to formally resolve al. (2002). the taxonomy and nomenclature of this group of Unnamed subgroups are formally named for the first snakes. time. Instead this paper’s main aim is to formally describe As mentioned in the abstract, the total number of and name the relevant groups at either the genus well-defined species groups for all rattlesnakes is level or the subgenus level as appropriate to resolve now nine (9) well defined genera, along with an and stabilize the taxonomy and nomenclature of the additional seven (7) well-defined subgenera within rattlesnakes in accordance with the ICZN’s rules as these. published in 1999 (effective 2000) (cited here as Hoser 2009 - Australasian Journal of Herpetology 6:1-21 Hoser 2009 - Available online at www.herp.net Copyright- Kotabi Publishing - All rights reserved Australasian Journal of Herpetology 3 ICZN 1999) and similar. subgroups, each at the genus level a long time ago. In the main the phylogeny accepted is similar to that Comparative splits of taxa as diverse as “Egernia” published by Murphy et. al. 2002, with relevant skinks and pythons in Australia (Wells and changes in accordance with findings by other Wellington (1984) and (for the “Egernia”), supported authors since then and allowing for the formal by Gardner et. al. 2008), and other groups initially descriptions or redefinitions of new taxa at various lumped in large genera for convenience’s sake have levels that have been accepted herein. long ago had their phylogeny’s sorted out and then A logical question that will be asked by some, is why been split into genera more reflective of the origins should the “established” genus “Crotalus” be split up and relationships of the component species. into the obvious subgroups with their own genus Put simply, the time has come for the same to be names? done for the group generally known as the In retort, I’d ask, why hasn’t it been split up already? rattlesnakes, now consisting of about fifty described and broadly accepted species level taxa and who’s In answer to the second question, which in part ancient origins are now not in doubt. answers the first I note the following. NOTES ON THE FOLLOWING DESCRIPTIONS Klauber’s seminal works on the rattlesnakes including Klauber 1972, were regarded by many as Detail has been kept to a minimum. the defining tome/s on these snakes. He For simplicity’s sake, generally recognised or named recognised just two genera (Sistrurus and Crotalus) subspecies have been generally ignored unless in line with most other herpetologists of the time.