Part 4

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 | | 22 | 68-74 | 70.3 | 2.14 | 0.46 | 3.04 | | | | | | | | | 1.97 | | 16 | 56-65 | 61.8 | 2.18 | 0.55 | 3.53 | | | | | | | | | lineatus dunni | | 14 | 67-80 | 74.5 | 3.86 | 1.03 | 5.18 | | | | | | | | | 0.95 | | 16 | 60-72 | 67.1 | 3.91 | 0.97 | 5.82 | | | | | | | | | lineatus lineatus | | 11 | 67-73 | 69.8 | 6.17 | 1.85 | 8.84 | | | | | | | | | 0.60 | | 9 | 60-66 | 62.4 | 6.17 | 2.06 | 9.89 | | | | | | | | | nevermanni | | 3 | 82-89 | 85.3 | .... | .... | .... | | | | | | | | | .... | | 2 | 71-76 | 73.5 | .... | .... | .... | | | | | | | | | pulcher | | 7 | 70-79 | 74.3 | 3.11 | 1.17 | 4.19 | | | | | | | | | 0.93 | | 11 | 65-71 | 68.2 | 3.42 | 1.08 | 5.01 | | | | | | | | | vittatus | | 95 | 59-76 | 67.8 | 3.33 | 0.34 | 4.91 | | | | | | | | | 1.28 | | 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.

=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.

Variation.--The variation in this species is discussed more completely in the descriptions of the subspecies. One hundred and seven specimens have 157 to 178 (164.8) ventrals. Eighty-eight of these snakes having complete tails have 56 to 80 (68.0) subcaudals; the number of ventrals plus subcaudals varies from 222 to 247 (233.5) in 87 of these. On 107 specimens the reduction from 19 to 17 dorsal scale-rows takes place between ventrals 89 and 114 (101.8). Sexual dimorphism is evident in the number of subcaudals; there are, on the average, fewer subcaudals in females than in males of each subspecies. The largest specimen is a male C. l. concolor (USNM 46345) from Chichen Itza, Yucatan, Mexico, having a body length of 893 mm., a tail length of 274 mm. and a total length of 1167 mm. The smallest is a juvenile C. l. dunni (MCZ 49749) from Tegucigalpa, Honduras, having a body length of 162 mm., a tail length of 51 mm. and a total length of 213 mm.

The greatest variation is in coloration. Dark color, or lack thereof, has been used to separate the subspecies of C. lineatus. The ground-color is pale brown, pale olive or white, either with no stripes on the body or with eight to thirteen dark stripes at mid-body. Specimens having dark stripes on the body always have black or dark brown pigmentation on the first, 4th and 7th dorsal scale-rows. In some there is dark pigmentation on the 2nd, 3rd, 8th and 10th rows of scales. The stripes appear on the nape or farther posteriorly, usually on the anterior third of the body, either as a series of spots or dashes that form a continuous stripe farther posteriorly or as a continuous stripe.

The ventrals usually have more or less conspicuous dark spots laterally on those specimens having dark stripes present on the dorsum; spots are absent on all specimens having no dorsal stripes and on some specimens having dorsal stripes. Except for the dark lateral spots (when present) the ventrals are immaculate white. Usually the dorsal ground-color is pale tan, especially on the striped forms. The ground-color is usually palest on the lower dorsal scale rows and darkest dorsally.

Three populations are separable as subspecies; one has no stripes on the body and occurs in the Yucatan Peninsula. The other two have stripes on the dorsum and vary clinally in coloration from the north (Veracruz, Mexico) to south (Costa Rica) (Fig. 2). Reasons for separating these widespread, variable snakes into two subspecies are that they are discontinuous in distribution (the population in Veracruz is disjunct from the one that extends from Guatemala to Costa Rica), and that these populations have distinctly different color patterns.

=Conophis lineatus dunni= Smith

Psammophis lineatus, Guenther, Catalogue of Colubrine Snakes in the Collection of the British Museum, p. 135, 1858.

Conophis lineatus, Cope, 3rd Ann. Rept. Peabody Acad. Sci., p. 82, 1871; Proc. Acad. Nat. Sci. Philadelphia, 23:204, October 24, 1871; Journ. Acad. Nat. Sci. Philadelphia, ser. 2, 8:137, 1876; Bull. U. S. Natl. Mus., 32:77, 1887; Guenther, Biologia Centrali-Americana, p. 165, March, 1895; Boulenger, Catalogue of the Snakes in the British Museum (Natural History), 3:122-123, 1896; Werner, Arch. Naturges., 90, abt. A, 12:143, 1925; Schmidt, Zool. Ser. Field Mus. Nat. Hist., 12:199-200, November 21, 1928; Amaral, Mem. Inst. Butantan, 4:212, 1929; Werner, Zool. Jahrb., 57:184, 1929; Stuart, Occas. Papers Mus. Zool. Univ. Michigan, 292:5, June 29, 1934; Dunn, Copeia, no. 4:214, December 31, 1937.

Conophis lineatus similis Smith, Journ. Washington Acad. Sci., 31:123-124, March 15, 1941 (Type.--United States National Museum, No. 79963; type locality.--Managua, Nicaragua; nec Bocourt in Dumeril, Bibron and Mocquard, Mission Scientifique au Mexique et dans l'Amerique Centrale, 2:647-648, 1886); Cochran, Bull. U. S. Natl. Mus., 220:167, 1961.

Conophis lineatus dunni Smith, Proc. U. S. Natl. Mus. 92:394-395, November 5, 1942; Savage, Trans. Kansas Acad. Sci., 50:483-486, December 31, 1949; Taylor, Univ. Kansas Sci. Bull., 34(pt. 1):145, October 1, 1951; Neill and Allen, Publ. Res. Div. Ross Allen's Rept. Inst., 2:56, November 10, 1959; Herpetologica, 16:146-148, fig. 2, September 23, 1960.

Conophis pulcher pulcher, Stuart, Misc. Publ. Mus. Zool. Univ. Michigan, 69:79, June 12, 1948; Contr. Lab. Vert. Biol. Univ. Michigan, 45:24, May, 1950; Contr. Lab. Vert. Biol. Univ. Michigan, 49:14, August, 1951; Contr. Lab. Vert. Biol. Univ. Michigan, 65:19-20 (part), March, 1954.

Conophis pulcher plagosus, Mertens, Zool. Anz., 148:93, February, 1952; Abhand. Senken. Naturw. Gesell., 487:61-62, December 1, 1952.

Conophis lineatus nevermanni, Taylor, Univ. Kansas Sci. Bull., 37(pt. 1):563-565, fig. 16, October 15, 1955.