Variation.—Thirty-six specimens have 159 to 178 (167.2 ± 4.56) ventrals. Thirty of these snakes having complete tails have 60 to 80 (70.5 ± 5.36) subcaudals; the number of ventrals plus subcaudals varies from 224 to 247 (237.6). In 36 specimens the reduction from 19 to 17 dorsal scales takes place between ventrals 91 and 111 (102.1 ± 4.59). Sexual dimorphism is evident in the number of subcaudals; 16 females have 60 to 72 (67.1), and 14 males have 67 to 80 (74.5) subcaudals. The largest specimen (ERA-WTN BH-300) is a female from Augustine, British Honduras, having a body length of 732 mm., a tail length of 183 mm. and a total length of 915 mm. A juvenile (MCZ 49794) from Tegucigalpa, Honduras, has 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. The ground-color is pale brown or white with dark stripes of black or deep brown present dorsally and laterally. Some specimens from Costa Rica have as many as 13 dark stripes at mid-body ([fig. 1, C]). In these snakes the first row of dorsal scales bears a series of large, slightly elongated, dark spots; on the 2nd row a narrow dark brown stripe on the middle of the scales; on the 3rd a black stripe on the dorsal one-third to one-half of the scales; on the 4th and the 7th rows black stripes on the medial half of the scales of each row; on the 8th and 10th (vertebral) rows dark brown stripes on the medial third of the scales of each row. A specimen from Guatemala (UMMZ 107339) shows the greatest reduction of stripes and dark pigmentation ([fig. 1, A]); it has only eight stripes at mid-body: on the first row of dorsal scales a discontinuous stripe is formed by a series of dashes; the 3rd row bears a series of small black spots near the base and tip of each scale; the 4th and 7th rows bear continuous black stripes on the medial third to fourth of the scales of each row; the 8th row has extremely small dark spots near the tips of some scales.
The primary stripes, characteristic of the species lineatus, are those on the 1st, 4th and 7th rows of dorsal scales; these are the most prominent stripes. In some specimens these primary stripes begin as spots or dashes on the nape and become continuous stripes posteriorly; in others they are continuous for the length of the body. The stripe on the 1st row is most variable; usually it consists of only a discontinuous series of dashes for most of its length. The secondary stripes are those on the 3rd and 8th rows; of these, only the one on the 3rd scale-row is present on the nape. The stripe on the 3rd row in combination with the dark stripe on the 4th row is the posterior continuation of the dark stripe that on the head passes through the eye; this stripe is characteristic of C. lineatus dunni. Both secondary stripes usually begin anteriorly as a series of spots or dashes and become continuous stripes posteriorly; occasionally near the base of the tail they fuse with the primary stripes on the 4th and 7th rows. In some specimens in Costa Rica indistinct stripes are present on the 10th (posteriorly the 9th) rows, and in some specimens in Honduras, Nicaragua, and Costa Rica similar indistinct stripes are present on the 2nd row.
Usually there are more or less conspicuous dark spots laterally on the ventrals, but in some specimens there are no spots. Except for the dark lateral spots (when present) the ventrals are immaculate white. The dorsal ground-color is a pale brown or brownish white in preserved specimens on the 1st, 2nd, 3rd and 4th rows of scales where dark stripes or spots are not present. The ground-color of the dorsum between the 5th rows on each side is a somewhat darker shade of pale to medium brown.
Never is more than the lower one-third of each of the supralabials brown. In many specimens little or no brown is present on the lower margins of these scales. Some of the specimens having brown on the supralabials also have dusky markings of tan or gray on the chin and infralabials. Specimens from the northern part of the range (Guatemala) less frequently have dark chins and supralabials than do specimens from the southern part of the range (Costa Rica). There is, nevertheless, at any one locality considerable variation in the amount of dark pigmentation present on the chin and supralabials, thereby indicating that the slight geographic trend in this character is not significant.
Probably the most common pattern of dorsal coloration consists of eight or ten dark stripes ([fig. 1, B]). In snakes having this pattern the stripes on the 1st, 3rd, 4th and 7th rows are always present and prominent, although those on the 1st and 3rd rows sometimes are present as discontinuous rows of dashes. The ground-color from the venter to the 7th row is usually pale brown, and that dorsally between the 7th rows on each side is usually a darker, medium brown. A series of spots or dashes or a continuous stripe is sometimes present on the 8th row of scales.
Snakes having a larger number of dark stripes and more dark pigmentation occur in the southern part of the range. There seems to be a cline from paler snakes having fewer stripes in the north to darker snakes in the south.
| Fig. 3. Patterns of dorsal coloration at mid-body of juveniles of two sympatric species of Conophis. A. C. lineatus dunni (MCZ 49794) from Tegucigalpa, Honduras. B. C. pulcher (MCZ 49791) from Tegucigalpa, Honduras. Approximately × 1. |
In juveniles, there are six or eight black stripes boldly contrasting with a white or pale tan ground-color ([fig. 3, A]). The first pair of stripes is on the 1st scale-row; the second pair, on the 3rd and 4th scale-rows; the third pair, on the 7th row; the fourth pair (when present), on the 8th row. Ontogenetic change in coloration consists of the splitting of the second pair of dark stripes in the juvenile. Additional stripes may form later on the 2nd and/or 10th rows of dorsal scales.
Remarks.—Savage (1949:483-486) stated that his specimen of C. l. dunni (from Honduras) resembled l. lineatus in having secondary stripes on the 2nd and 8th rows and dark pigmentation throughout the length of the 2nd row. As can be seen from the preceding discussion of variation, a specimen having this color pattern is clearly within the observed range of variation of l. dunni. The specimen in no way represents an intergrade between C. l. dunni and l. lineatus.