REPTILIA: SQUAMATA: SERPENTES: COLUBRIDAE 352.1 TRIMORPHODON Catalogue of American Amphibians and Reptiles. SCOTT, NORMAN J., JR., AND ROY W. MCDIARMID. 1984. Tri- morpkodon. Trimorphodon Cope Lyre Snakes Trimorphodon Cope, 1861:297, Type species, Lycodon lyro- phanes Cope, 1860, by original designation. Eteirodipsas Jan, 1863:105. Type species, Dipsas biscutata Du- m?ril, Bibron, and Dum?r?l, 1854, by subsequent designation (Smith and Taylor, 1945; Mertens, 1952). Hetaerodipsas Berg, 1901:90. Emendation of Eteirodipsas Jan. ? CONTENT. TWO species are recognized: T biscutatus and T. tau. ? DEnNlTlON AND DuGNOSis. A colubrid snake genus with lat- eral head scales fragmented, numerous, and variable in number, loreols generally 2 or 3 (2-5), preoculars generally 3 or 4 (2-5), postoculars generally 3 (2-4), temporals generally 2 or 3 (1-5) + 3 or 4 (2-5); supralabials genereUy 8 or 9 (7-10), infraiabials generally 11 or 12(9~14); dorsal scales smooth (or bluntly keeled in some males) with paired apical pits, generally in 21-25 rows at midbody with posterior reductitxi; anal plate divided or single; sub- caudals paired; head distinct from body; eye moderate to large with vertically elliptical pupil; body and taU moderately slender to very slender and laterally compressed; length to over 1500 mm; color pattern composed of black or brown blotches, usually with pale centers which tend to divide the primary Uotches into secondary blotches which in turn may be divided; small blotches sometimes present dorsally between large blotches or laterally in a row; head pattern tisually complex with a broad pale collar (tau) or pale chev- ron or lyre (most biscutatus) on the nape; pale interocular bor often present; ground color brown, tan, gray, or brick red with juvenile color pattern more intense and sharply defined; venter paler than dorsum and noticeably opalescent, may be spotted or mottled. Maxillary teeth 10-12, anterior 2 or 3 much larger than others which gradually decrease in size posteriorly to diastema wliich is followed by 1 or 2 enlarged teeth, deeply grooved on anterior face; anterior mandibular teeth enlarged; Duvernoy's gland well developed. Vertebrae short, broad and flat; wider than long, neural spine low and thin; haemal spine barely indicated as a slightly raised keel. Hypapophyses blade-like, present on anterior vertebrae only. Hemipenis 14-25 si?icaudals long, single, and attenuate; sul- cus single, reaching to tip; basal quarter naked, with or without tiny spinales; next distal fifth with thickened sulcal lips and covered with large spines and spinules, or naked (specimens from southern and Baja California); this part followed by two or three pockets on asulcate aide with naked pouches and thick, spinulate lips; these pockets followed by a short naked neck that ends in another pocket under the distal portion of the organ, which is finger-shaped and covered with rows of spinulate papillae. Both species are nocturnal, oviparous, and primarily feed on lizards. In North and Ontral American colubrid snakes, an undivided sulcus spermaticus, elliptical pupil, generally smooth scales, and enlarged grooved posterior maxillary teeth preceded by a diastema, define three genera: Leptodeira, Imantodes, and Trimorphodon (Dunn, 1928). Trimorphodon is further distinguished by having more than one loreal, a pocketed, non-capitate hemipenis, and slighdy oblique scale rows (Duelfanan, 1958). ? DESCRIPTIONS. Generic descriptions are found in Cope (1861, 1900), Boulenger (1896), Brown (1901), Phisalix (1922), Taylor (1939), and Duellman (1958); hemipenes ore described by Klauber (1940) and Smith (1941). ? ILLUSTRATIONS, See species accounts. ? DISTRIBUTION. The genus ranges from southern California, southern Nevada, southwestern Utah, Arizona, southern New Mex- ico, and western Texas south through the entire peninsula of Baja California, on (^rralvo, San Marcos, and Tibur?n islands of the Gulf of California, in all of the Pacific states of M?xico plus Chi- huahua, [hirongo, Tamaulipas, Aguascalientes, Guanajuato, Hidal- go, M?xico, Morelos, Puebla, (^eretaro, San Luis Potos?, Veracruz, and Zacatecas; through the Pacific lowlands and some dry interior valleys of Guatemala, Honduras, El Salvador, and Nicaragua to Guanacaste and Puntarenas provinces of northwestern Costa Rica. A record for Panam? (Boulenger, 1896) is not confirmed and prob- ably erroneous. Elevational range from sea level to 2600 m. ? FOSSIL RECORD. See species accounts. ? PERTINENT LITERATURE. McDiarmid and Scott (1970) re- viewed T. tau, and Gehlbach (1971) revised T. biscutatus-, see these and the species accounts for additional references. ? KEY TO SPECIES, Pole band on nape broad with a straight or slightly indented posterior border; most dorsal dark saddles confluent with dark markings on ventrals 7^ tau Pale band on nape narrow and chevron or lyre shaped, posterior border A or U-shaped; most dorsal dark saddles separated from dark spots on tips of ventrals T. biscutatus ? NOMENCLATURAL HISTORY. Cope (1861) described Trimor- phodon based on specimens of Lycodon lyrophanes Cope from Baja California Sur, the description of Dipsas biscutata Dum?ril, Bibron, and Dum?ril from M?xico, and a specimen that Cope ex- amined from Nicaragua, Both taxa are now included in T biscu- tatus. In 1869, Clope described three additional forms: 71 tau, upsilon, and major. McDiarmid and Scott (1970) showed that 7ri- morpkodon tau and upsilon represented one species {T. iau); T. major was made a synonym of T. biscutatus (Cope, 1887), Sub- sequent work consisted of two stages, a long period during which several new forms were described, and a recent period during which all of these have been assigned to one of the two species now composing the genus (see references in Species Accounts). Eteirodipsas was described by Jan (1863) to include Dipsas biscutata, Dvun?ril, Bibron, and Dum?ril, Dipsas colubrina Schle- gel, Coluber annulatus Linnaeus, and rhomboidalis Jan, a variety of E. annulatus. Jan's (1863; Jan and Sordelli, 1872) biscutata included both species (biscutatus and tau) currently in Trimorpho- don. Boulenger (1896) placed biscutatus in Trimorphodon and annulatus in Leptodeira (rhomboidalis is a nomen nudum), re- taining colubrina as the only species of Eteirodipsas. Smith and Taylor (1945) explicitly designated Dipsas biscutata as the type species of Eteirodipsas (Mertens, 1952). ? ETYMOLOCY, Trimorphodon refers to the three tooth shapes in the upper jaw: the long, recurved anterior teeth, the shorter middle teeth, and the elongate, grooved fangs at the rear. The gender is masculine. MAP. Shading indicates estimated range of the genus Trimorpho- don. Open circles indicate presumed isolated populations; question marks indicate areas where the genus probably occurs but no rec- ords are available and a questionable record from Guatemala. 352.2 COMMENT The placement of Trimorphodon within the family Colubridae is probably as unsettled as that of any genus. Cope (1900) placed it with a group of 13 Old and New World genera characterized by grooved fangs and a calyculate or spinose hemipenis with a single sulcus spermaticus. Although Cope (1900) mentioned "calyces few and irregular" on the hemipenis of Trimorpkodon, neither Cope's drawings (Plate 28, Figure 7) nor our observations indiate calyces. Dunn (1928) rejected the emphasis that Cope placed on grooved fangs and included Trimorphodon with Hypsiglena and Lepto- deira in a colubrine group having enlarged rear teeth either grooved or not and a capitate hemipenis with a simple sulcus. We do not know bow Dunn defined a capitate hemipenis, but we do not con- sider that of Trimorphodon to be capitate because the capitulum does not have a free overhanging edge on the sulcate side. Dunn (1928) may have been repeating Cope's observations that the head is very distinct. Dueilman (1958), using Dunn's arrangement, com- pared the same three genera and concluded that Trimorphodon was distantly related to the other two. Underwood (1967), using hemipenial and retinal characters, tenatively placed Trimorphodon and Hypsiglena in one heterogeneous family (Natricidae) and Lep- todeira in another (Homakipsidae). DowUng (1975) doubtfully placed Trimorphodon in a small tribe with Phyllorhynchu? and the ori- ental Oligodon because it did not fit well elsewhere. However Dow- ling and Dueilman (1978) returned to the classification of (>ope (1893, et seq.), and included the genus in a heterogeneous array of neotropical forms. This placement conflicts with the biocheinical data which agree in allying Trimorphodon with a group of mostly North American genera, including Elapke, Pituophis. and Lam- propeltis (Georgfi and Dessauer, 1970; Minton and Salanitro, 1972; Schwaner and Dessauer, 1982; Cjidle, in press). These studies also coincide in placing the relationships of Trimorpkodon far from the North American Nerodia-lhamnophii series (George and Des- sauer, 1970; Minton and Salanitro, 1972), from Leptodeira and other neotropical xenodontines (Minton and Salanitro, 1972; Cadle and Sarich, 1981; Cadle, in press), and from various elapids and Cr?talos (Cadle and Sarich, 1981; Cadle and (Gorman, 1981). On the other band. Bury et al. (1970) showed that the karyotype of Trimorphodon is distinct from a variety of genera from western North America, including Lampropeltis and Pituophis, Most early attempts to clarify the relationships of Trimorphodon have been misled by an inadequate description of the hemipenis and by the unusual combination of characters (e.g., vertical pupil; enlarged, grooved posterior maxillary teeth; noncalyculate hem^ienis with large pockets), and even now no close relatives of Trimorpkodon have been identified. LITERATURE CITED Berg, Charles. 1901. Herpetological notes. Comun. Mus. Nac. Buenos Aires l(8):289-291. Boulenger, George A. 1896. Catalogue of the snakes m the British Museum (Natural History). Vol. 3. London, xiv + 727 p. Brown, Arthur E. 1901. A review of the genera and species of American snakes north of Mexico. Proc. Acad. Natur. Sei. Philadelphia 33:10-110. Bury, R. Bruce, Franklin Cress, and Oorge C. Gorman. 1970. Koryotypic survey of some colubrid snakes firom western NiKth America. Herpetologica 26(4):461-466. Cadle, John E. In press. Phylogenetic relationships among ad- vanced snak?: a molecular perspective. Univ. of CaUfomia, Publ. Zool. ?, and George C. Gorman. 1981. Albumin immunological evi- dence and the relationships of sea snakes. J. Herpetol. 15(3): 329-344. ?, and Vincent M. Sarich. 1981. An immunological assessment of the phylogenetic position of New World coral snakes. J. Zool.. London 195:157-167. Cope, Edward D. 1860. Notes and descriptions of new and little known species of American reptiles. Proc. Acad. Natur. Sei. Philadelphia 12:339-345. ? 1861. Contributions to the ophiology of Lower California, Mexico and Central America. Ibid. 13:292-306. ? "1869" (1870). Seventh contribution to the herpetology of tropical America. Proc. Amer. Phil. Soc. 11:147-169, ? 1887. Catalogue of the batrachians and reptiles of Central America and Mexico. Bull. U.S. Nat. Mus. (32): 1-98. ? 1893. Prodromus of a new system of the non-venomous snakes. Amer. Natur. 27(3l7):477-483. ? 1900. llie crocodilians, lizards, and snakes of North Amer- ica. Ann. Rep. U.S. Nat. Mus. 1898:153-1270 -I- 36 pi. DowUng, Hemdon G. 1975. The nearctic snake fauna, p. 190- 202. In H. G. DowUng (ed.) 1974 yearbook of herpetology. Herpetological Information Search Systems (8):v -i- 256. ?, and William E. Dueilman. 1978. Systematic herpetology: a synopraa of families and higher categories. Herpetological In- formation Search Systems (7):vii 4-147-1- viii. Dueilman, William E. 1958. A monographic study of the colubrid snake genus Leptodeira. Bull. Amet. Mus. Natur. Hist. 114(1): 1-152. Dum?ril, Andre M. C, CaMel Bifaron, and Auguste Dum?ril. 1854. Erp?tologie g?n?rale ou histoire naturelle compl?te des reptiles. Vol. 7, part 2. Librairie Encyclopedkpie de Roret, Paris. 755 p. Dunn, Emmett R. 1928. A tentative key and arrangment of the American genera of colubridae. Bull. Antivenin Inst. Amer. 2(l):18-24. Gefalbach, Frederick R. 1971. Lyre snakes of the Trimorphodon bitcutatus cranplex: a tanmcoiiic resume. Herpetokigica 27(2): 200-211. Gewge, Daniel W., and Herbert C. Dessauer. 1970. Immunolog- ical correspondence of tronsferrins and the relationships of colubrid snakes. Corop. Biochem. Physiol. 33:617-627. Ian, Georges. 1863. Elenco sistem?tico degli ofidi descritti e disegnati per I'iconografia gen?rale. Lombardi, Milan, vii -H 143 p. ?, and Ferdinand Sordelti. 1872. Iconographie g?n?rale des ophidiens. Milan. Vol. 3, livr. 39, pL 1, fig. 3. Klauber, Laurence M. 1940. The lyre snakes (genus Trimorpho- don) of the United States. Trans. San Diego Soc. Natur. Hist. 9(19):163-194. McDiarmid, Roy W., and Norman J. Scott, Jr. 1970. Gec^apbic variation and systematic status of Mexican lyre snakes of the Trimorphodon tau group (Colubridae). Los Angeles County Mus. Contrib. Sei. (179):l-43. Mertens, Robert. 1952. Nomenklatorisches ?ber die Schlangen- gattung Eteirodipsas. Senckenbergiana 32(5-6):307-308. Minton, Sherman A., Jr., and Sylvia K. Salanitro. 1972. Sero- logicai relationships among some colubrid snakes. Copeia 1972(2):246-252. Phisaliz, Marie. 1922. Animaux venimeux et venins. Vol. 2. Masson et Cie, Paris. 864 p. Scfawaner, Terry D., and Herbert C. Dessauer. 1982. Compara- tive bnmunodiffusion survey of snake transferrins focused on the relationships of the natricines. (?apeia 1982(3):541-549. Smith, Hobart M. 1941. Notes on the snake genus Trimorpho- don. Proc. U.S. Nat. Mus. 91(3130):149-168. ?, and Edward H. Taylor. 194S. An annotated checklist and key to the snakes of M?xico. U.S. Nat. Mus. Bull. (187):iv -h 1-239. Taylor, Edward H. "1938" (1939). On Mexican snakes of the genera Xrimjorphodon and Hypsiglena. Univ. Kansas Sei. BuU. 25(16):357-383. Underwood, Garth. 1967. A contribution to the classification of snakes. Trustees British Mus. (Natur. Hist.), London, x H- 179 p. NORMAN J. SCMTT, JR., U.S. FISH AND WIIFUFE SERVICE, UNIVERSITY OF NEW MEXICO, ALBUQUERQUE, NEW MEXICO 87131 AND ROY W. MCDIARMID, U.S. FISH AND WILDUFE SERVICE, NA- TIONAL MUSEUM OF NATURAL HISTORY, WASHINGTON, D.C. 20560 Primary editor for this account, Larry David Wilson. Published 10 October 1984 and Copyright 1984 by the SOCIETY FOR THE STUDY OF AMPHIBIANS AND REPTILES.