Oriental Rat Snake

Ptyas mucosa, commonly known as the Oriental rat snake, or Indian rat snake, is a common non-venomous species of colubrid snake found in parts of South and Southeast Asia. These are large snakes. Typical mature total length is around 1.5 to 1.95 m (4 ft 11 in to 6 ft 5 in) though some exceed 2 m (6 ft 7 in). The record length for this species was 3.7 m (12 ft 2 in), second only to their cousin Ptyas carinata among living colubrid snakes. Despite their large size, oriental ratsnakes are usually quite slender with even a specimen of 2 m (6 ft 7 in) commonly measuring 4 to 6 cm (1.6 to 2.4 in) only around in diameter. Furthermore, the average weight of ratsnakes caught in Java was around 877 to 940 g (1.933 to 2.072 lb), though larger males of over 2.3 m (7 ft 7 in) (which average mildly larger of the two sexes in the species) may easily weigh over 2.5 kg (5.5 lb). Their color varies from pale browns in dry regions to nearly black in moist forest areas. Rat snakes are diurnal, semi-arboreal, non-venomous, and fast-moving. Rat snakes eat a variety of prey and are frequently found in urban areas where rodents thrive.

Etymology

The International Code for Zoological Nomenclature (ICZN) directs that the grammatical gender of any given species name should follow logically from the gender of its associated genus name. As Ptyas is a feminine word form (from πτυάς, a Greek word for a venom-spitting snake), the proper form of the species name is mucosa (a Late Latin word meaning "slimy"). Reference materials older than 2004 often show the masculine form, mucosus, and the CITES list continues to list the species this way.

Distribution

Found in Afghanistan, Bangladesh, Myanmar, Cambodia, China (Zhejiang, Hubei, Jiangxi, Fujian, Guangdong, Hainan, Guangxi, Yunnan, Tibet, Hong Kong), Taiwan, India (including Andaman and Nicobar Islands), Sri Lanka, Indonesia (Sumatra, Java, Bali), Iran, Laos, West Malaysia, Nepal, Myanmar, Pakistan (Sindh area), Thailand, Turkmenistan and Vietnam.

Description

Description from Boulenger's Fauna of British India: Reptilia and Batrachia volume of 1890:

Snout obtuse, slightly projecting; eye large; rostral a little broader than deep, visible from above; suture between the internasals shorter than that between the prefrontals; frontal as long as its distance from the end of the snout, as long as the parietals or slightly shorter; usually three loreals; one large preocular, with a small subocular below; two postoculars; temporals 2+2; 8 Upper labials, fourth and fifth entering the eye; 5 Lower labials in contact with the anterior chin shields, which are shorter than the posterior; the latter in contact anteriorly. Dorsal scales in 17 rows at midbody, more or less strongly keeled on the posterior part of the body. Ventrals 190–208; anal divided; subcaudals 95–135, divided. Brown above, frequently with more or less distinct black crossbands on the posterior part of the body and on the tail; young usually with light crossbands on the front half of the body. Lower surface yellowish; the posterior ventral and the caudal shields may be edged with black.