Chironius fuscus (Linnaeus)

Myers, C. W. & Donnelly, M. A., 2008, The Summit Herpetofauna Of Auyantepui, Venezuela: Report From The Robert G. Goelet American Museum-Terramar Expedition, Bulletin of the American Museum of Natural History 2008 (308), pp. 1-147 : 121-123

Chironius fuscus (Linnaeus) Figure 73

Coluber fuscus Linnaeus, 1758: 222–223 . ‘‘ Habitat in Asia’’ in error.

Chironius fuscus: Roze, 1966: 97 . Peters and Orejas-Miranda, 1970: 60. Dixon et al., 1993: 113, 261 (generic revision; BMNH specimen listed from ‘‘south side Auyantepui, 2283 m [in error for 6850 ft. 5 2088 m]’’).

MATERIAL: Southern side of Auyantepui (‘‘below final cliff face’’), 6850 ft. [2088 m]: BMNH 1976.235, collected by Adrian Warren, August 17, 1974. Camp 3, 1850 m: AMNH R-155717 (fragment of shed skin, tentatively identified), from the 1994 AMNH –TERRAMAR Expedition to Auyantepui.

The one whole summit specimen (fig. 73) is a female, probably subadult, 937 mm total length, 279 mm tail length (29.8 % of total length). Dorsal scales completely smooth except for a few weak anal ridges laterally above cloacal region, in 10-10-10 rows; apical pits absent. Ventrals 158, subcaudals 103, paired; anal plate entire. Supralabials 9/8, 2nd–3rd touching loreal, 4th–6th in eye; infralabials 8, first five touching anterior genials. Preoculars 1, postoculars 2. Temporals 1 + 1. About 41 maxillary teeth on right. Color in preservative indistinctly marked with dark gray transverse bands; the bands are separated by white middorsal scales anteriorly on the body and by whitish transverse lines posteriorly. These markings along with black scale edges and small spots give an overall mottled appearance of gray, black, and white (fig. 73 top).34 Supralabials mostly yellowish white, with labials 2–3 having dark posterior edges. An ill-defined

34 Some remaining patches of stratum corneum suggest that the living coloration is in shades of brown.

black postocular stripe extending from eye across lower part of primary temporal and upper part of ultimate supralabial. Underside of head immaculate yellowish white; black transverse lines across bases of anterior ventrals, these lines becoming heavier, with intervening black spots posteriorly (fig. 73 bottom).

The fragment of shed skin is from a small snake of juvenile size. The scales are relatively large, in 10 rows anteriorly, eight rows posteriorly; no keeled scales are discernible; apical pits absent over most of body, but relatively large pits are present on some scales posteriorly on the neck, with paired pits being more common than single ones. The eyes are relatively large; there are two postoculars and 1 + 2 temporals; both postocular scales are in contact with the primary temporal. Anal plate torn.

REMARKS

The shed skin from Camp 3 is fragmentary but identifiable to genus and may also represent Chironius fuscus , although the possibility of a second congener on the Auyán summit cannot be excluded. Most other Chironius species in southern Venezuela ( carinatus , exoletus , and multiventris) are differentiated from the material at hand by presence of 12 rows of dorsal scales anteriorly and at midbody. Chironius scurrulus has 10 midbody rows of smooth (unkeeled) scales, as do the whole specimen and skin fragment from Auyantepui; these materials, in fact, key out to scurrulus in Dixon et al. (1993: 57). However, immature fuscus may lack completely the key character of keeling ( Dixon et al., 1993: 116); the whole specimen (fig. 73) has a color pattern consistent with fuscus and this identity was confirmed by Dixon et al. (1993: 261) in their Specimens Examined section.

Roze (1958a: 266; 1966: 95) listed three Auyantepui specimens of Chironius carinatus from the 1937–1938 AMNH–Phelps Venezuelan Expedition. The AMNH catalog shows that all were collected well below the summit. Two specimens (AMNH R-61020, 61024) were collected by W. H. Phelps at 1100 m (3609 ft.). The third specimen (AMNH R-61036) was obtained by Phelps near the base of Auyantepui, at 460 m (1509 ft.). The last is a specimen of Chironius exoletus according to Dixon et al. (1993: 258 in Specimens Examined).