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# A Revision of Snakes of the Genus Conophis (Family Colubridae, from Middle America) ### By Wellman, John

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UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Volume 15, No. 6, pp. 251-295, 9 figs.

October 4, 1963

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

BY JOHN WELLMAN

UNIVERSITY OF KANSAS LAWRENCE 1963

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Theodore H. Eaton, Jr.

Volume 15, No. 6, pp. 251-295, 9 figs. Published October 4, 1963

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY JEAN M. NEIBARGER. STATE PRINTER TOPEKA. KANSAS 1963

[Illustration: Union Label]

29-5936

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

BY

JOHN WELLMAN

CONTENTS

PAGE

INTRODUCTION 253

ACKNOWLEDGMENTS 254

MATERIALS AND METHODS 254

GENUS Conophis Peters 255 Key to the Species and Subspecies 257 Analysis of Characters 257 Scutellation 258 Size and Proportions 258 Color Pattern 260 Sexual Dimorphism 260 _C. lineatus_ 262 _C. lineatus dunni_ 262 _C. lineatus lineatus_ 267 _C. lineatus concolor_ 270 _C. nevermanni_ 272 _C. pulcher_ 274 _C. vittatus_ 277 Skull 282 Dentition 288 Vertebrae 288 Hemipenes 289 Food and Feeding 289 Effect of Poison 290

TAXONOMIC RELATIONSHIPS AND EVOLUTION 291

SUMMARY 292

LITERATURE CITED 293

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 Institute; 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 assistance. 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 assisting 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 manuscript.

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 anal 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 anal 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 pass 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 Institute 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), Guenther, 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, Klassen 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. Essex 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 Guenther (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._--Hemipenis 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; supralabials, 7-8, 3rd and 4th or 4th and 5th under eye; infralabials, 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; anal 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 supralabials (3rd and 4th below orbit); 3 to 8 dark stripes along body 2

Eight supralabials (4th and 5th below orbit); unstriped or with more than 4 dark stripes along body, or dark with 2 or 4 pale stripes 3

2. Dark stripes involving no more than one longitudinal scale-row _C. lineatus lineatus_ (part), p. 267

Dark stripes involving at least two adjacent scale-rows _C. vittatus_, p. 277

3. Supralabials having black borders above; head and body generally black with 2 or 4 white lines running length of body _C. nevermanni_, p. 272

Supralabials immaculate or having dark borders below; head and body usually pale with dark stripes, or without stripes 4

4. Lateral dark stripe through eye involving upper half of second scale-row; dark stripe on paravertebral row, at least posteriorly _C. pulcher_, p. 274

Lateral dark stripe becoming indistinct on body, or restricted to 4th or 3rd and 4th rows anteriorly, not involving 2nd scale-row on anterior 1/3 of body (an auxiliary lateral stripe sometimes present involving 2nd row); no paravertebral stripes 5

5. Stripes disappearing posteriorly (except for small spots of pigment on scale-row 4 or 7); 1st scale-row unpigmented _C. lineatus concolor_, p. 270

Stripes present posteriorly; 1st scale-row pigmented 6

6. Lateral stripes narrow on nape, restricted to 4th scale-row on body _C. lineatus lineatus_ (part), p. 267

Lateral stripes involving 3rd and 4th rows, at least on nape _C. lineatus dunni_, p. 262

Analysis of Characters

Characters showing inter-specific and intra-specific variation and that have a wide range of variation were analyzed statistically, when possible, in order to determine extent of variation. One character (see table 3) was analyzed for sexual dimorphism, and for it the coefficient of difference is also given. The statistical terms and formulae have been adopted from Mayr, Linsley and Usinger (1953). Dorsal head shields varied individually and were of no taxonomic importance. Osteological and hemipeneal characters did not show enough variation to be considered here.

Scutellation

Labials, dorsals, ventrals, and subcaudals were the most useful scales.

_Labials._--All species usually have eight supralabials except _C. vittatus_, which has seven. The only other population having a relatively high frequency of occurrence of seven supralabials is _C. l. lineatus_. In specimens having eight supralabials, the fourth and fifth enter the orbit; in specimens having seven supralabials, the third and fourth enter the orbit (the second and third are fused). Usually there are ten infralabials, sometimes nine or eleven; specimens having seven supralabials usually have nine infralabials, sometimes eight, rarely ten.

_Dorsals._--Although there is no variation in the number of rows of dorsal scales, there is some in the method of scale reduction. There are 19 rows of dorsal scales from close behind the head to about midway on the body where two rows are lost, leaving 17 rows from there to near the base of the tail. This reduction is accomplished by fusion of the scales of the 3rd and 4th rows or sometimes by the dropping out of the 3rd row. The place at which reduction occurs in number of dorsal scales in relation to the ventral (scale) directly below is highly variable and of little taxonomic importance (table 1).

TABLE 1.--VARIATION IN THE PLACE OF DOSAL SCALE REDUCTION IN CONOPHIS.

Key to Columns ==================================== Std. Dev. = Standard Deviation Std. Err. = Standard Error Coe. Var. = Coefficient of Variation

==============+===========+========+=======+======+======+====== | Number of | | | Std. | Std. | Coe. Taxon | Specimens | Range | Mean | Dev. | Err. | Var. --------------+-----------+--------+-------+------+------+------ _l. concolor_ | 45 | 89-114 | 102.5 | 5.57 | 0.83 | 5.43 _l. dunni_ | 36 | 91-111 | 102.1 | 4.59 | 0.77 | 4.50 _l. lineatus_ | 26 | 91-107 | 100.2 | 3.59 | 0.72 | 3.58 _nevermanni_ | 6 | 84- 97 | 93.2 | 4.71 | 1.92 | 5.05 _pulcher_ | 26 | 94-119 | 104.6 | 4.90 | 0.96 | 4.68 _vittatus_ | 170 | 84-118 | 102.3 | 6.60 | 0.16 | 6.45 --------------+-----------+--------+-------+------+------+------

_Ventrals._--The number of ventral scutes varies from 149-183, and shows no significant variation in the means (table 2).

_Subcaudals._--The number of subcaudal scutes varies from 55 to 89. In some populations there is no overlap in the range of variation of males and females. The total variation and sexual dimorphism are analyzed in table 3.

Size and Proportions

Although considerable variation in size is observable, little taxonomic use is made of size since sufficient series are not available to determine age classes. The subspecies attaining the largest size is _C. lineatus concolor_; all others are smaller and of about the same size and proportions. The longest specimen, a male of _C. l. concolor_, has a body length of 893 mm., a tail length of 274 mm., and a total length of 1167 mm.

TABLE 2.--VARIATION IN THE NUMBER OF VENTRALS IN CONOPHIS.

Key to Columns ==================================== Std. Dev. = Standard Deviation Std. Err. = Standard Error Coe. Var. = Coefficient of Variation

==============+===========+=========+=======+======+======+====== | Number of | | | Std. | Std. | Coe. Taxon | Specimens | Range | Mean | Dev. | Err. | Var. --------------+-----------+---------+-------+------+------+------ _l. concolor_ | 45 | 158-170 | 163.7 | 1.56 | 0.23 | 0.95 _l. dunni_ | 36 | 159-178 | 167.2 | 4.56 | 0.76 | 2.72 _l. lineatus_ | 26 | 157-169 | 163.5 | 3.59 | 0.72 | 2.20 _nevermanni_ | 6 | 173-183 | 176.5 | 4.00 | 1.63 | 2.27 _pulcher_ | 26 | 149-180 | 169.5 | 5.31 | 1.04 | 3.13 _vittatus_ | 171 | 149-180 | 163.7 | 6.33 | 0.15 | 3.87 --------------+-----------+---------+-------+------+------+------

TABLE 3.--SEXUAL DIMORPHISM AS INDICATED BY VARIATION IN THE NUMBER OF SUBCAUDALS IN CONOPHIS.

Key to Columns ==================================== Num. Spc. = Number of Specimens Std. Dev. = Standard Deviation Std. Err. = Standard Error Coe. Var. = Coefficient of Variation Coe. Dif. = Coefficient of Difference

====================+=====+====+=======+======+======+======+======+===== | |Num.| | | Std. | Std. | Coe. | Coe. Taxon | Sex |Spc.| Range | Mean | Dev. | Err. | Var. | Dif. --------------------+-----+----+-------+------+------+------+------+----- _lineatus concolor_ | [M] | 22 | 68-74 | 70.3 | 2.14 | 0.46 | 3.04 | | | | | | | | | 1.97 | [F] | 16 | 56-65 | 61.8 | 2.18 | 0.55 | 3.53 | | | | | | | | | _lineatus dunni_ | [M] | 14 | 67-80 | 74.5 | 3.86 | 1.03 | 5.18 | | | | | | | | | 0.95 | [F] | 16 | 60-72 | 67.1 | 3.91 | 0.97 | 5.82 | | | | | | | | | _lineatus lineatus_ | [M] | 11 | 67-73 | 69.8 | 6.17 | 1.85 | 8.84 | | | | | | | | | 0.60 | [F] | 9 | 60-66 | 62.4 | 6.17 | 2.06 | 9.89 | | | | | | | | | _nevermanni_ | [M] | 3 | 82-89 | 85.3 | .... | .... | .... | | | | | | | | | .... | [F] | 2 | 71-76 | 73.5 | .... | .... | .... | | | | | | | | | _pulcher_ | [M] | 7 | 70-79 | 74.3 | 3.11 | 1.17 | 4.19 | | | | | | | | | 0.93 | [F] | 11 | 65-71 | 68.2 | 3.42 | 1.08 | 5.01 | | | | | | | | | _vittatus_ | [M] | 95 | 59-76 | 67.8 | 3.33 | 0.34 | 4.91 | | | | | | | | | 1.28 | [F] | 58 | 55-66 | 60.0 | 2.75 | 0.36 | 4.58 | --------------------+-----+----+-------+------+------+------+------+-----

Color Pattern

This is the primary feature used to separate species and subspecies in this genus. The color pattern consists of three black or deep brown stripes on the dorsal part of the head, one mid-dorsally, and one on each side of the head passing through the eye. On the body, there are usually dark longitudinal stripes on a pale tan or white background. There may be as few as three in _vittatus_, and as many as 13 in _l. dunni_; except that there is none in _C. l. concolor_. There are two pairs of primary dark stripes. The first is the body stripe that is the posterior extension of the stripe which on the head passes through the eye and is termed the lateral stripe. The other primary stripe is the posterior continuation of the mid-dorsal head stripe. Usually it is split into two dorsolateral stripes on the body. Stripes may be present on the scale-row to either side of the primary stripe. These stripes are usually dark brown or black and are the secondary stripes. Finally, additional stripes may be present that are paler brown and bear no direct relationship to the primary stripes. These are auxiliary stripes.

Every stripe originates either as broad continuous stripe or as a row of spots or dashes, forming a discontinuous stripe, which in some specimens becomes continuous posteriorly. The stripes are usually black or deep brown, although auxiliary stripes are sometimes paler. The dorsal ground color is pale brown, tan, olive, or white; usually the ground color is palest ventrally and darkest dorsally.

In some specimens of _Conophis_ the lateral tips of the ventrals are spotted, one spot on each end of each ventral. Otherwise, the ventrals are immaculate white.

In some species there is considerable ontogenetic change in color pattern, although the juveniles bear the basic color characteristics of the adults. For example, juveniles of the sympatric species _C. lineatus dunni_ and _C. pulcher_ can be separated on the basis of which scale-rows are darkly pigmented. _C. l. dunni_ has eight stripes in juveniles and as many as 13 in adults. Juveniles show a greater contrast between the black stripes and the pale ground color than do adults. With increased age (size) the stripes in some populations become paler and are split; simultaneously the ground color becomes darker.

Sexual Dimorphism

Sexual dimorphism is evident in all species and subspecies of _Conophis_. Differences always exist in the number of subcaudals and in the tail/body ratio; males have more subcaudals and relatively longer tails than do females (table 3). Otherwise, there is little sexual dimorphism in these snakes. Males and females cannot be differentiated by any feature of coloration.

Formulation of a biological concept of the species as defined by Mayr (1942) is difficult when most of the data primarily relied upon are from preserved specimens. Nevertheless, a total view of variation was attempted so that differences within and between populations could be recognized. Differences, between populations, that seem to be part of a continuous or internal cline (Huxley, 1942) are not used for characterizing subspecies.

[Illustration: FIG. 1. Patterns of dorsal coloration at mid-body of adults of all species and subspecies of the genus _Conophis_ except _C. lineatus concolor_. A. _C. lineatus dunni_ (UMMZ 107339) from Santa Rosa, Guatemala. B. _C. lineatus dunni_ (UMMZ 116537) from 1.5 mi. N Matagalpa, Nicaragua. C. _C. lineatus dunni_ (ANSP 3480) from "San Jose," Costa Rica. D. _C. l. lineatus_ (KU 23253) from Rio Blanco, 20 km. WNW Piedras Negras, Veracruz, Mexico. E. _C. nevermanni_ (ANSP 22424) "San Jose," Costa Rica. F. _C. pulcher_ (UIMNH 33646) from Soconusco, Chiapas, Mexico. G. _C. vittatus_ (KU 39626) from Atencingo, Puebla, Mexico. H. _C. vittatus_ (TCWC 9473) from 1 mi. S Colotlipa, Guerrero, Mexico. I. _C. vittatus_ (UMMZ 82653) from "vicinity of" Salina Cruz, Oaxaca, Mexico. Approximately x 3/4.]

=Conophis lineatus= (Dumeril, Bibron and Dumeril)

_Tomodon lineatum_ (in part) Dumeril, Bibron and Dumeril, Erpetologie Generale, 7(pt. 2):936-938, February 25, 1854.

_Diagnosis._--No dark pigmentation posterior to nape; lateral dark stripe anteriorly passing through eye and posteriorly involving 4th or 3rd and 4th scale-rows only; first scale-row darkly pigmented; no paravertebral dark stripe; six to thirteen (or no) dark stripes at mid-body; usually eight (sometimes seven) supralabials immaculate white or having dark ventral margins.