Hypnale walli

Hypnale walli, or Wall's hump-nosed viper,[2] is a venomous pitviper species endemic to Sri Lanka. The smallest member of its genus, it is distinguished by having a strongly upturned nose and lower scale counts. No subspecies are currently recognized.[3]

Hypnale walli
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Hypnale
Species:
H. walli
Binomial name
Hypnale walli
Gloyd, 1977
Synonyms[1]
  • Ancistrodon hypnale
    — Boulenger, 1896 (part)
  • Ancistrodon millardi
    — Wall, 1921 (part?)
  • Ancistrodon nepa
    — M.A. Smith, 1943 (part)
  • Agkistrodon nepa
    — Deraniyagala, 1955 (part?)
  • Hypnale walli
    Gloyd, 1977

Etymology

The specific name, walli, is in honor of Ceylonese-born British herpetologist Frank Wall.[4]

Description

The smallest member of the genus Hypnale, the only male with a complete tail measured 30.5 cm (12.0 in) in total length with a tail of 4.3 cm (1 3⁄4 in) (14% of total length), while the largest female was 28.3 cm (11 1⁄4 in) in total length with a tail of 3.5 cm (1 1⁄2 in) (12% of total length). The body is stoutly built.[2]

This species is distinguished from H. hypnale by a snout that has a strongly upturned tip. This is due to an extended rostral scale, which is immediately followed by a raised wart-like hump covered with 10 minute scales. Also, the hemipenes have clearly visible spines. It is distinguished from H. nepa by its lower scale counts.[2]

The scalation includes 17 rows of dorsal scales at midbody that usually lack keels, 7 supralabial scales, 120-126 ventral scales, and 28-33 subcaudal scales.[2]

Regarding the color pattern, Gloyd and Conant (1990) examined a number of preserved specimens, mentioning that some were so faded as to render the pattern almost invisible. One of these, however, had a faint narrow stripe down the center of its back. In general, the color pattern is described as consisting of a series of 18-24 dorsolateral small subtriangular brown blotches, pointing upwards. These are slightly darker than the ground color, except for the upper edges that may be considerably darker. A pair of dark brown blotches are present on the side of the head, along with a pair of dark stripes curving backward on the sides of the neck. The ventral surface is strongly flecked and dappled with grayish brown.[2]

Geographic range

Hypnale walli is found in Sri Lanka. The type locality given is "Kanneliya Forest, Udugama Southern Province, Ceylon [Sri Lanka], elevation approximately 1,000 ft [300 m]".[1]

Taxonomy

According to Gloyd and Conant (1990), the taxonomic status of this species is unclear. Although described here as a species, it may eventually be classified as a subspecies of H. nepa, or even as the minimum extreme for H. nepa with regard to its low ventral and subcaudal scale counts, as well as its relatively short tail.[2]

References
  1. McDiarmid RW, Campbell JA, Touré T (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  2. Gloyd HK, Conant R (1990). Snakes of the Agkistrodon Complex: A Monographic Review. Oxford, Ohio: Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. ISBN 0-916984-20-6.
  3. "Hypnale walli". Integrated Taxonomic Information System. Retrieved 8 August 2008.
  4. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Hypnale walli, p. 279).

Further reading
  • Gloyd HK (1977). "Descriptions of new taxa of crotalid snakes from China and Ceylon (Sri Lanka)". Proc. Biol. Soc. Washington 90: 1002-1015. ("Hypnale walli, new species", pp. 1011-1014).
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