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Psammophis leightoni BOULENGER, 1902

Abstract from Taft, J. M., Maritz, B., & Tolley, K. A. (2021).

Climate shifts during the Quaternary Period have driven changes in regional range dynamics for many species, influencing population structure of species and in some cases promoting speciation. Within southern Africa, the psammophine snakes Psammophis trinasalis and P. namibensis were historically considered subspecies of P. leightoni but were elevated to species rank based on
ecological differences. Preliminary phylogenetic analyses suggested intraspecific, not interspecific genetic variation between these taxa, but this finding was based on very limited data and could not be confirmed. To assess the level of genetic differentiation within the P. leightoni species complex, we explored the evolutionary history of these snakes by combining phylogenetic analyses, species distribution modelling and an examination of morphology. We generated a comprehensive, multi-gene phylogeny for Psammophis that included wider geographic sampling of the three species in the complex. Using this phylogeny, Bayesian and distance-based species delimitation analyses showed intraspecific, not interspecific divergences between taxa in the complex, suggesting that they  collectively represent a single taxon. Furthermore, non-metric multidimensional scaling analysis of scalation characters showed no differences between the species.
Moreover, palaeo-modelling at three time periods since the last interglacial period suggest tat there have been varying levels of connectivity between these taxa, which has likely facilitated gene flow between them. Given the evidence, we propose that the P. leightoni complex represents a single species and therefore formally synonymise the three species.

Discussion paragraph in Taft e.a. 2021:
"The currently described species within the Psammophis leightoni complex form a single, well-supported clade. Genetic structure within this clade divergences are shallow compared to other species in the genus, and our analyses indicate the clade represents a single, widespread taxon rather than three separate species. Likewise, species distribution models suggest that there has been connectivity among the distributions of the three taxa, but the degree of connectivity has varied over time. Despite some variation in body coloration and patterning across the range, there are no morphological differences to support their status as separate species. Therefore, we revise the taxonomy by formally relegating both P. namibensis Broadley, 1975 and P. trinasalis Werner, (1902) into synonymy with P. leightoni Boulenger, 1902. Psammophis leightoni Boulenger, 1902 published in February 1902 takes precedence over P. trinasalis Werner, 1902 published in March 1902.

 


 

Subspecies Psammophis leightoni trinasalis WERNER 1902 and Psammophis leightoni namibensis BROADLEY 1975 have been elevated to full species status, but Taft e.a. 2021 revised this again.
Common Names Cape Sand Snake 
Synonym Psammophis leightoni BOULENGER 1902
Psammophis leightoni — BROADLEY 2002
Psammophis leightoni — MATTISON 2007: 111 
Distribution Republic of South Africa (W Cape Province)  

Reptile Atlas of Southern Africa: click here to find a distribution map

   
Comment Nomenclature: PETERS’ name is a junior homonym of Psammophis furcatus (BIANCONI 1859) = Psammophis punctulatus DUMÉRIL & BIBRON 1854.

Distribution: see map in BROADLEY 2002.

Description: (24 specimens examined). Nostril pierced between 3 nasals, upper posterior with a posterior prolongation; preocular 1, in broad contact with frontal; postoculars 2; temporals basically 2+2+3, but with frequent fusions; supralabials 8, fourth & fifth entering orbit; infralabials 10 (rarely 9), the first 4 in contact with anterior sublinguals; dorsal scales in 17-17-13 rows; ventrals 155-169; cloacal shield divided; subcaudals 92-112. Brandstätter (1995, Fig. 45) has published a SEM micrograph of a dorsal scale from NMZB 3570 from the Cape Flats.
Dark brown above, top of head with a yellow stripe along the internasal/prefrontal sutures, most of supralabials, pre- and post-oculars yellow, two yellow bars across back of head. Vertebral scale row with a fine yellow line (often broken up), a yellow lateral stripe passes through scale rows 3 & 4 or fourth only, scales in outer row white at base (Broadley 1983, Fig. 84). The “chain pattern” on the side of the neck is illustrated by Boulenger (1902, pl. xii). Chin with a pattern of black streaks, ventrals with a mottled grey median band, widened at the free edge of each ventral and fading posteriorly [from BROADLEY 2002]. 
References
  • Auerbach,R.D. 1987. The Amphibians and Reptiles of Botswana. Mokwepa Consultants, Botswana, 295 pp.
  • Bauer, A.M., and Branch, W.R. 2003. The herpetofauna of the Richtersveld National Park, Northern Cape Province, Republic of South Africa. Herpetological Natural History 8: 111-160 [2001]
  • Bauer, Aaron M.; Branch, William R. & Haacke, Wulf D. 1993. The herpetofauna of the Kamanjab area and adjacent Damaraland, Namibia. Madoqua (Windhoek), 18 (2): 117-145.
  • Bauer,A.M.; Günther,R. & Klipfel,M. 1995. The herpetological contributions of Wilhelm C.H. Peters (1815-1883). SSAR Facsimile Reprints in Herpetology, 714 pp.
  • Boulenger, G. A. 1902. Description of a new snake of the genus Psammophis, from Cape Colony. Proc. Zool. Soc. London 1902: 126 - get paper here
  • Branch, William R. 1993. A Photographic Guide to Snakes and Other Reptiles of Southern Africa. Cape Town: Struik Publishers, 144 S.
  • Broadley, D.G. 1975. A review of Psammophis leightoni and Psammophis notosticus in southem Africa (Serpentes: Colubridae). Arnoldia 7 (13): 1-17
  • Broadley, D.G. 2002. A review of the species of Psammophis Boie found south of Latitude 12° S (Serpentes: Psammophiinae). African Journal of Herpetology 51 (2): 83-119
  • FitzSimons, V.F.M. 1974. A field guide to the snakes of Southern Africa. 2nd edition. COLLINS, 221 pp. [first ed. 1970]
  • Fitzsimons, V.F.M.; Brain, C.K. 1958. A Short account of the Reptiles of the Kalahari Gemsbok National Park. Koedoe, 1(1): 99-104 - get paper here
  • Mattison, Chris 2007. The New Encyclopedia of Snakes. Princeton University Press
  • Peters, Wilhem Carl Hartwig 1867. Über eine Sammlung von Flederthieren und Amphibien aus Otjimbingue in Südwestafrica, welche Hr. Missionär Hahn dem zoologischen Museum zugesandt hat. Monatsber. königl. Akad. Wiss. Berlin. 1867 (April): 234-237
  • Shine, Richard; William R. Branch, Jonathan K. Webb, Peter S. Harlow, and Terri Shine 2006. Sexual Dimorphism, Reproductive Biology, and Dietary Habits of Psammophiine Snakes (Colubridae) from Southern Africa. Copeia 2006 (4): 650-664
  • Werner, F. 1902. Über westafrikanische Reptilien. Verh. Zool. Bot. Ges. Wien 52: 332-348
 
 

http://www.animalsandearth.com/en/photo/view/id/37827-fork-marked-sand-snake-psammophis-leightoni-on-pebbles-and-fine-sand-namib-desert-namibia#/1/tag/Psammophis%20Leightoni/viewed/

Hunter and Habitat in the Central Kalahari Desert, by George B. Silberbauer:

 

Sources

The Reptile Database