A Revision of Snakes of the Genus Conophis Part 1

A Revision of Snakes of the Genus Conophis (Family Colubridae, from Middle America).

by John Wellman.

INTRODUCTION

Need for a comprehensive systematic review of the snakes of the genus _Conophis_ was pointed out by Stuart (1954a, b). Since these snakes appeared to be of zoogeographic importance in the Central American region, I undertook the review as set forth on the following pages.

ACKNOWLEDGMENTS

For permission to examine specimens, and for information concerning specimens in their care, I am grateful to Mr. L. C. Battersby and Miss Alice G. C. Grandison, British Museum (Natural History); Mr. Charles M. Bogert and Dr. Richard G. Zweifel, American Museum of Natural History; Dr. Doris M. Cochran, United States National Museum; Prof.

William B. Davis, Agricultural and Mechanical College of Texas; Dr.

Josef Eiselt, Naturhistorisches Museums, Vienna; Prof. Norman Hartweg and Prof. Laurence C. Stuart, Museum of Zoology, University of Michigan; Dr. Robert F. Inger, Chicago Natural History Museum; Dr.

Alan E. Leviton, California Academy of Sciences; Mr. Edmond V.

Malnate, Academy of Natural Sciences, Philadelphia; Prof. George S.

Myers, Stanford University Natural History Museum; Mr. Wilfred T.

Neill, Ross Allen's Reptile Inst.i.tute; Mr. Neil D. Richmond, Carnegie Museum; Dr. William J. Riemer, University of Florida Collections; Prof. Robert C. Stebbins, Museum of Vertebrate Zoology, University of California; Prof. Hobart M. Smith, University of Illinois Natural History Museum; and Dr. Ernest E. Williams, Museum of Comparative Zoology, Harvard.

Prof. William E. Duellman supplied invaluable information and guidance in my study. I am grateful to Prof. E. Raymond Hall for use of facilities of the Museum of Natural History and editorial a.s.sistance.

I thank Prof. Laurence C. Stuart and Prof. Edward H. Taylor for information and suggestions. My own field experience in Middle America came as a result of a.s.sisting Professor Duellman in his own researches supported by a grant from the National Science Foundation (NSF-G 9827). For these things I am deeply grateful. Specimens that I have seen alive were collected by field companions Dale L. Hoyt and Jerome B. Tulecke. Finally, I am grateful to my wife, Margaret L. Wellman, for much help including typing much of the ma.n.u.script.

MATERIALS AND METHODS

Of the 325 specimens of the genus _Conophis_ available to me, representing most of those in museum collections, scale counts were made in the usual manner on 309. Ventrals were counted following the system proposed by Dowling (1951:97-99); the a.n.a.l plate was not included. The anteroposterior position of the place where reduction occurs in the number of the dorsal rows of scales is designated by citing the number of the ventral scale directly beneath that place.

Measurements were taken to the nearest millimeter by means of a millimeter stick. Body length is the distance from the tip of the snout to the posterior edge of the a.n.a.l plate; tail length, from the latter point to the tip of the tail; and total length, the sum of the body plus tail.

Descriptions of color are based on preserved specimens. Where descriptions of the color of living individuals are given, the data were taken from Kodachrome slides made available to me by William E.

Duellman. Due to the transient nature of the longitudinal dark stripes in these snakes, no standard terminology has been devised, except that the posterior continuations of the stripes which on the head pa.s.s through the eye are termed lateral stripes; the posterior continuations of the median stripe of the head are termed dorsolateral stripes. A paravertebral stripe is one that is present on the scale-row on either side of, but not including, the mid-dorsal (vertebral) scale-row.

In order to reduce confusion in the discussion of variation, the numbers designating the rows of dorsal scales are written as 1st, 2nd, whereas the numbers designating the stripes are written as first, second.

Except in three dried skeletons, teeth were counted on dentigerous bones _in situ_. Since teeth are often missing, the sockets were counted in order to obtain an accurate count.

In accounts of the species and subspecies, the observed range of variation is followed by the mean in parentheses; in some instances the mean is followed by the standard deviation, also in parentheses.

An example is 65-79 (70.6 3.93).

Each synonymy includes all generic and specific combinations known to me that have been used for the genus, and, in addition, references to catalogues, checklists, and reports of collections.

Localities of occurrence that are not plotted on the distribution maps are recorded in italic type under Specimens Examined. In the list of Specimens Examined the localities and specimens are listed in the following order: countries in alphabetical order; states or departments in alphabetical order in each country; localities in alphabetical order in each state or department; museum numbers in numerical order after the abbreviations of names of museums. When more than one specimen bears a single catalogue number, the number of specimens is given in parentheses following the museum catalogue number. Specimens for which data are given only as to country or to state or department are listed first after the name of that political unit under "no specific locality."

The abbreviations for the museum collections are:

AMNH American Museum of Natural History ANSP Academy of Natural Sciences of Philadelphia BMNH British Museum (Natural History) CAS California Academy of Sciences CNHM Chicago Natural History Museum ERA-WTN E. Ross Allen-Wilfred T. Neill, Ross Allen's Reptile Inst.i.tute KU University of Kansas Museum of Natural History MCZ Museum of Comparative Zoology, Harvard MVZ Museum of Vertebrate Zoology, University of California NMW Naturhistorisches Museums Wien, Vienna SU Stanford University Natural History Museum TCWC Texas Cooperative Wildlife Collection, Agricultural and Mechanical College of Texas UF University of Florida Collections UIMNH University of Illinois Museum of Natural History UMMZ University of Michigan Museum of Zoology USNM United States National Museum

Family COLUBRIDAE

Subfamily Xenodontinae

Genus =Conophis= Peters

_Tomodon_ (part) Dumeril, Bibron and Dumeril, Erpetologie Generale, 7(pt.2):936, February 7(pt.2):936, February 25, 1854 (_lineatus_ and _vittatus_); Salvin, Proc. Zool. Soc. London, 28:455, 1860 (_pulcher_).

_Psammophis_ (part), Gunther, Catalogue of Colubrine Snakes in the Collection of the British Museum, London, 1858:135 (_lineatus_).

_Conophis_ Peters, Monatsb. Akad. Wiss. Berlin, 1860:519-520, pl., fig. 3 (_vittatus_); Cope, Proc. Acad. Nat. Sci.

Philadelphia, 13:300, December 28, 1861 (_lineatus concolor_); Proc. Acad. Nat. Sci. Philadelphia, 18:318-319, February 20, 1867 (_lineatus concolor_); Proc. Acad. Nat. Sci.

Philadelphia, ser. 2, 8:137, 1876 (_pulcher_); Bocourt in Dumeril, Bocourt and Mocquard, Mission Scientifique au Mexique et dans l'Amerique Centrale, 2:643-644, pl. 38, fig. 5, 1886 (_lineatus lineatus_); Cope, Proc. Amer. Philos. Soc., 23:489, October 28, 1886; Hoffmann, Kla.s.sen und Ordnungen des Thier-Reichs. Reptilien. Bd. 6, 3:1707, 1890; Cope, Trans.

Amer. Philos. Soc., 18:207, April 15, 1895; Dunn, Bull.

Antivenin Inst. Amer., 2(1):21, 24, April, 1928; Copeia, no.

4:214, December 31, 1937 (_nevermanni_).

_Tachymenis_ (in part), Garman, Bull. Ess.e.x Inst., 16:33, January 9, 1884 (_vittatus_ and _lineatus_).

_Erythrolamprus_ (in part), Ditmars, Bull. Antivenin Inst.

Amer., 2(2):27-29, June.

_Coniophanes_ (in part), Wettstein, Sitz. Akad. Wiss. Wien, mathem-naturw. kl. 143:37-38, 1934 (_nevermanni_).

_Historical summary._--In 1854 Dumeril, Bibron and Dumeril described and figured _Tomodon lineatum_ from America. In 1860 Peters described and figured as a new genus and species, _Conophis vittatus_, based on a specimen that he had obtained from a dealer in Hamburg. The provenance of this specimen is not known, for it was discovered aboard a ship near the mouth of the Mississippi River. It was not until 1871 that Cope included _lineatus_ in the genus _Conophis_. Cope (1861) proposed the name _Conophis vittatus_ (_nec_ Peters, 1860). Later (1900) he changed its name to _Conophis lineaticeps_. Early uncertainty of the relationships of the species _lineatus_ caused Gunther (1858) to place it in the genus _Psammophis_. With the exception of Garman (1884a and 1884b) who placed _lineatus_ in the genus _Tachymenis_, and Wettstein (1934) who reported five specimens of _Conophis nevermanni_ as _Coniophanes i. imperialis_, all specimens reported after 1876 were placed in the genus _Conophis_.

The only previous attempt to review the systematics of this genus was made by Smith (1941) who based his study primarily on specimens in the United States National Museum. He examined only 28 specimens, including none of one species (_nevermanni_).

_Description._--Hemip.e.n.i.s slightly bifurcate having forked sulcus spermaticus, large spines near base, and smaller spines or papillae on flounces nearer apices; prediastemal maxillary teeth 8-12, subequal in length, and followed by short diastema and one enlarged fang or two; fangs grooved, only one functional at any one time, unless snake is in process of shedding teeth; teeth 6-10 on palatine, 15 to 19 on pterygoid, 15 to 21 on dentary; teeth on dentary decreasing in size posteriorly; large parotid (venom) gland on either side of head in temporal region; head shields of basically unmodified colubrid type excepting decurved rostral; rostral concave below and therein modified for burrowing; internasals and prefrontals paired; nasals divided; loreal single; preocular one, rarely two; postoculars, two; supral.a.b.i.als, 7-8, 3rd and 4th or 4th and 5th under eye; infral.a.b.i.als, 8-11, usually 9 or 10; temporals, normally 1 plus 2 plus 3; chin-shields subequal in length; ventrals, 149-183, rounded and overlapping; caudals, 55-89, paired and imbricate; a.n.a.l divided; dorsal scales smooth and in 19 rows at mid-body with no apical pits or keels; scale reduction normally involving fusion of 3rd and 4th rows, resulting in 17 scale-rows near tail; tail length more than 20 per cent of body length; maximum total length exceeding 1.1 meters; dorsal color pattern consisting of dark stripes, or no darkening, on paler ground-color; ventral surfaces immaculate pale yellowish or white, except on specimens having single lateral dark spots on some or all ventrals; pupil round; diurnal or crepuscular; feeding primarily on small lizards, sometimes on small mammals or other snakes.

_Distribution._--Semi-arid regions of southern Mexico and Central America as far south as Costa Rica.

KEY TO THE SPECIES AND SUBSPECIES

Although many juveniles differ greatly in general coloration from the adults, both the juveniles and the adults of any species or subspecies can be identified from the following key; juveniles differ from adults in extent and intensity of dark pigmentation but not in rows of scales involved.

1. Seven supral.a.b.i.als (3rd and 4th below orbit); 3 to 8 dark stripes along body 2

Eight supral.a.b.i.als (4th and 5th below orbit); unstriped or with more than 4 dark stripes along body, or dark with 2 or 4 pale stripes 3