Thursday, March 3, 2016

[Herpetology • 2016] Wallaceophis gujaratensis • A New Miocene-Divergent Lineage of Old World Racer Snake (Serpentes: Colubridae) from India


Wallaceophis gujaratenesis 
Mirza, Vyas, Patel, Maheta & Sanap, 2016

Abstract

A distinctive early Miocene-divergent lineage of Old world racer snakes is described as a new genus and species based on three specimens collected from the western Indian state of Gujarat. Wallaceophis gen. et. gujaratenesis sp. nov. is a members of a clade of old world racers. The monotypic genus represents a distinct lineage among old world racers is recovered as a sister taxa to Lytorhynchus based on ~3047bp of combined nuclear (cmos) and mitochondrial molecular data (cytb, ND4, 12s, 16s). The snake is distinct morphologically in having a unique dorsal scale reduction formula not reported from any known colubrid snake genus. Uncorrected pairwise sequence divergence for nuclear gene cmos between Wallaceophis gen. et. gujaratenesis sp. nov. other members of the clade containing old world racers and whip snake is 21–36%.

Fig 6. Wallaceophis gen. etgujaratensis sp. nov. holotype male NCBS HA-105 in life.
Photo by Z. Mirza.  DOI: 10.1371/journal.pone.0148380 

Systematics

Wallaceophis gen. nov. Mirza, Vyas, Patel & Sanap, 2016.
urn:lsid:zoobank.org:act:43CA682D-4EE0-4653-95B6-6F4E0C2FAEDE

Type species: Wallaceophis gujarateneis sp. nov.

Diagnosis: A medium sized snake in relation to members of the family measuring SVL 250–930 mm differing from most colubrid genera in lacking hypapophyses on posterior dorsal vertebrae (Fig 2) and in bearing nine maxillary teeth and the posterior-most teeth are subequal, nine palatine teeth. Dorsal scale reduction characterized by vertebral reductions, increase of scale rows posterior to neck, a single lateral reduction at midbody and regular vertebral reductions in posterior half of the body. Rostral not visible from above, a small presubocular present. Eight supralabials, fourth and fifth in contact with orbit, anal undivided, 215–216 ventrals, 51–54 subcaudals, hemipenis subcylindrical, spinose throughout and 3–4 dorsal scale row wide black longitudinal stripe running from the post nasal to the tail tip on each side on a wheat colored dorsum.


Wallaceophis gen. nov. may be distinguished from most members of the family Colubridae in lacking hypapophyses on posterior dorsal vertebrae. This condition is present in racers and whip snake of the genera Platyceps, Hemorrhois, Spalerosophis, Hemerophis, Dolichophis, Hierophis, Eirenis, Orientocoluber, Coluber, Macroprotodon, Bamanophis and Lytorhynchus. Wallaceophis gen. nov. differs from these genera in bearing unique vertebral dorsal scale reductions (vs. lateral reductions in Platyceps, Hemorrhois, Hemerophis, Dolichophis, Hierophis, Eirenis, Orientocoluber, Coluber, Macroprotodon, Bamanophis and Lytorhynchus); nine maxillary teeth (vs. 15–17 in Spalerosophis, 14–19 in Platyceps, 13–16 in Hemorrhois, 17–20 in Hemerophis, 16–18 in Hierophis, 16–26 in Eirenis, 15–19 in Bamanophis); presubocular present (vs. absent in Macroprotodon, Orientocoluber, Bamanophis). The new genus is closely related to the genus Lytorhynchus based on ~3047bp of nuclear and mitochondrial gene sequences however differs from it in having vertebral dorsal scale reduction (vs. lateral in Lytorhynchus); nine palatine teeth (vs. 3–5 in Lytorhynchus).

Etymology: The proposed generic name is a compound of two words, the first being a patronym honoring Alfred Russel Wallace for his pioneering work on biogeography and for co-discovering the theory of natural selection with a suffix ‘ophis’ (όφις) meaning snake in Greek. Gender of the proposed generic name is masculine.


Fig 6. Wallaceophis gen. et. gujaratensis sp. nov. holotype male NCBS HA-105 head illustration showing scalation, (A) lateral view, (B) dorsal view.

Wallaceophis gujaratensis sp. nov. Mirza, Vyas, Patel, Maheta & Sanap, 2016.
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Holotype: male, NCBS HA-105, collected from Khengariya village, Viramgam taluka, Ahmedabad district, Gujarat state, India (23.0217946 N, 72.0217584 E, altitude 21m) by Jaydeep Maheta on 24th July 2014.
Paratypes: female BNHS 3503, collected form near Amreli, Amreli district,
Gujarat state, India by Viral Joshi on 20th March 2013.

Etymology: The specific epithet refers to Gujarat state in western India where the new species was discovered.

Suggested common name: Wallace’s striped snake/ Wallace’s racer


Natural History & Distribution: The type specimen was collected from a manmade water hole near an irrigation canal along with a few juveniles of Xenochropis piscator. The species appears to be diurnal as it was collected at ca. 11:15 hours. The type locality, Khengariya village, is situated in the dry plains of central-western region of Gujarat state. According to Champion and Seth [29] the type locality falls under Desert thorn forest. The floral composition of this area is made up of Acacia senegal, Acacia leucophloea, Euphorbia neriifolia, Capparis spp., Zizyphus spp., etc. The region falls under the drier parts of the country. The annual precipitation is 838mm. Majority of the precipitation occurs during the months of July and August. The temperature varies from as low as 12°C during winter and as high as 43°C during the hot summer days. These conditions create a harsh environmental condition for any life form living in this area. The snake was immersed in water to wash it upon which the snake dived to the base of the bucket and remained submerged for about five minutes. The holotype was also found in water suggesting that the snake might prefer areas in proximity to water sources. While photographing the snake, the snake made attempts to dig into the substrate which suggest that the snake is fossorial in nature. An individual retained in captivity was offered a Hemidactylus sp. which was readily accepted. We have also been able to collect the secondary information about the species’ habits and habitat from local ‘snake rescuers’ and wildlife photographers on the basis of colored images/photographic evidences. This yielded information denotes that the species inhabits other parts of the state too, including the holotype, paratype and the specimen NCBS HA-108 (Fig 7). The information from various sources and collection sites of specimens shows that species is distributed in four different sub biotic land regions as 4B1Saurashtra Plateau, 4B2-Bhal, 4B4 Plains and 4B5Plains of Gujarat and this entire land mass further falls in 4B Semi-Arid Gujarat-Rajputana Provinces as per the Biogeographic Zone Classification of Rodgers and Panwar. For a summary of distribution localities.


Discussion and Conclusion

Phylogenetic analysis based on a total of 3047bp of concatenated nuclear and mitochondrial genes shows that Wallaceophis gen. nov. is a member of a clade of arid snake species within Colubrinae containing the genera Hemorrhois, Platyceps, Hierophis, Hemerophis, Eirenis, Dolichophis, Orientocoluber, Bamanophis, Macroprotodon and Lytorhynchus (Fig 8). The relationships recovered from our analysis are congruent with those of Pyron et al.. Wallaceophis gen. nov. is genetically most similar to the genus Lytorhynchus with an uncorrected pairwise sequence divergence of 21.5% for nuclear cmos gene and is recovered as a sister taxa of the new genus with a deep divergence. The new genus shows 23–36% uncorrected pairwise sequence divergence for nuclear cmos gene from other genera of the clade (Table 3). Our analyses are preliminary and must however be confirmed after incorporation of more taxa of the genus Lytorhynchus as well as data for additional nuclear genes. Based on morphology Wallaceophis gen. nov. can be readily distinguished from all members of the old world racers in have a unique dorsal scale row reduction pattern in addition to bearing fewer maxillary teeth.


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Zeeshan A. Mirza, Raju Vyas,  Harshil Patel,  Jaydeep Maheta  and  Rajesh V. Sanap. 2016. A New Miocene-Divergent Lineage of Old World Racer Snake from India. PLoS ONE. 11(3): e0148380. DOI: 10.1371/journal.pone.0148380

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