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Psammophine snakes

 

Presentation

Let us first start with an instructive presentation by the well known herpetologist Stephen Spawls.
City College Norwich biology and chemistry lecturer, Mr Spawls, from Spixworth, grew up in Kenya and it was here that he developed his enduring interest as a herpetologist. He has had a lifelong interest in African wildlife, and a particular passion for snakes and chameleons. For the books he wrote about African herpetology, click here.
Click on the picture or here to see the presentation, or click to download a Powerpoint Presentation.
 

 


Classification

Classification schemes are dependant on the actuality of papers on which they are based. A full classification scheme can be found on the webiste of Animal Diversity Web, but this is already outdated.

Vidal e.a. 2007 "investigated the higher-level relationships of caenophidian snakes with seven nuclear protein-coding genes and obtained a well-supported topology. Accordingly, some adjustments to the current classification of Caenophidiaare made to better reflect the relationships of the groups. The phylogeny also indicates that, ancestrally, caenophidian snakes areAsian and nocturnal in origin, although living species occur on nearly all continents and are ecologically diverse." The for our group of snakes relevant part of their taxonomic classification scheme is:

Superfamily Elapoidea Boie, 1827
Family Elapidae Boie, 1827
    (Subfamilies: Elapinae Boie, 1827 and Hydrophiinae Fitzinger, 1843)
Family Lamprophiidae Fitzinger, 1843
    (Subfamilies: Psammophiinae Bonaparte, 1845, Atractaspidinae Günther, 1858,
    “Lamprophiinae” Fitzinger, 1843 and “Pseudoxyrhophiinae” Dowling, 1975)

In Vidal e.a. (2008) the classification is given more in detail:
" The Elapoidea includes the Elapidae and a large (~60 genera, 280 sp.) and mostly African (including Madagascar) radiation termed Lamprophiidae by Vidal et al. (2007), that includes at least four major groups: the psammophiines, atractaspidines, lamprophiines and pseudoxyrhophiines." And: "The lamprophiids (~60 genera, 280 sp.) include four major groups: the psammophiines (~7 genera, 42 sp.), atractaspidines (~12 genera, 70 sp.), lamprophiines (~ 19 genera, 88 sp.) and pseudoxyrhophiines (~20 genera, 80 sp.) (Vidal 2002; Vidal & Hedges 2002a; Vidal et al. 2007). Following Vidal et al. (2007, 2009), Fry et al. (2008), and Vonk et al. (2008), we treat these groups as subfamilies of the African lamprophiid radiation, although others have afforded them family status, including Lamprophiidae, Psammophiidae, Pseudoxyrhophiidae (Kelly et al. 2008) and  Atractaspididae (Branch 1998; Zaher 1999; Shine et al. 2006), while additional families, Prosymnidae (genus Prosymna) and Pseudaspididae (genera Pseudaspis and Pythonodipsas), have recently been proposed (Kelly et al. in press).

Scheme from Vidal a.o. 2007:

In 2011 Pyron e.a presented a new, large-scale, likelihood-based phylogeny for the colubroids, including 761 species sampled for up to five genes. The following scheme is for Psammophiinae.

First, Pyron e.a. define crown-group Colubroidea to consist of the extant families Colubridae, Elapidae, Homalopsidae, Lamprophiidae, Pareatidae, Viperidae, and Xenodermatidae. The result for the psammophiids is:

Superfamily Colubroidea. Family Lamprophiidae, Subfamily Psammophiinae    

In their view the correct term for the family is also Psammophiinae.

Kelly 2008:

A recent paper is Christopher M.. Kelly, Nigel P. Barker, Martin H. Villet, Donald G. Broadley and William R. Bran, The snake family Psammophiidae (Reptilia: Serpentes): Phylogenetics and species delimitation in the African sand snakes (Psammophis Boie, 1825) and allied genera. (2008). They describe the family as follows:

"Psammophiidae Bourgeois, 1968 occurs throughout Africa, the Middle East, Madagascar, southern Europe and south-central Asia, and currently includes eight genera and about 50 extant species (Table 1), of which around 30 belong to the type genus Psammophis Boie, 1825. Other genera include Dipsina Jan, 1863 (one species), Dromophis Peters, 1869 (two species), Hemirhagerrhis Boettger, 1893 (four species), Malpolon Fitzinger, 1826 (three species), Mimophis Günther, 1868 (one species), Psammophylax Fitzinger, 1843 (four species), and Rhamphiophis Peters, 1854 (five species)."

Concerning the place of former Rhamphiophis acutus within the family, they conclude:
"In clade B, the strong support for a sister relationship between Psammophylax and R. acutus renders the genus Rhamphiophis diphyletic. Broadley (1971) provides a review and taxonomic history of R. acutus, noting that in several respects (dentition and colouration) this taxon forms a link between Rhamphiophis and Psammophylax. The most distinctive synapomorphy of Rhamphiophis is its shortened and reinforced skull (adaptations for digging), a characteristic that is less pronounced in R. acutus ([Broadley, 1971] and [Chirio and Ineich, 1991]). It is clear that this character is homoplasious, and we transfer the three subspecies of R. acutus to the genus Psammophylax, i.e. Psammophylax acutus acutus (Günther, 1888) (comb. nov.), Psammophylax acutus jappi (Broadley, 1971) (comb. nov.) and Psammophylax acutus togoensis (Matschie, 1893) (comb. nov.). "

The consequence for the dentition description of Psammophylax is:
"This change increases the dental variation in Psammophylax and necessitates the following modification to the diagnosis provided by Broadley (1977b): ‘The maxilla bears 9–13 subequal teeth, separated by a diastema from two enlarged grooved fangs on the posterior end of the bone; palatine teeth 7–11; pterygoid 9–23; dentary 15–24.’"

Concerning the place of Dromophis within the family, they conclude:
"Dromophis praeornatus and Dromophis lineatus occupy divergent and well-supported positions nested deeply within Psammophis, in clades 5 and 7 respectively (Fig. 1). We therefore relegate the genus Dromophis to the synonymy of Psammophis, forming Psammophis praeornatus (Schlegel, 1837) (comb. nov) and Psammophis lineatus (Dumèril & Bibron, 1854) (comb. nov.). "

The consequence for the dentition description of Psammophis is:
"The generic diagnosis provided for Psammophis by Broadley (1983) should thus be modified as follows: ‘Maxillary teeth usually 10–16, 3–5 small teeth anteriorly, followed after a distinct interspace by two much enlarged recurved and fang-like teeth (below anterior border of eye), which are followed, after a second interspace, by 3–7 small teeth and then two strongly enlarged grooved fangs (below the posterior border of the eye). In P. praeornatus and P. lineatus (formerly assigned to the genus Dromophis) there is a continuous series of 10–16 small teeth (median longest) preceding the large grooved fangs below the posterior border of the eye. Anterior mandibular teeth strongly enlarged.’ "


Characteristics

Philippe Geniez, Alexandre Cluchier & Cornelius C. De Haan, 2006 describe the Psammophiinae in the following way.
Psammophines are a colubrid tribe or subfamily of mostly African snakes, consisting of 8 genera and about 44 species. These are characterized, in males, by their tiny hemipenes, quasi filiform and 3-4 subcaudals short (BOGERT 1940) and, in both sexes, by their valvular nostril enabling “self-rubbing” (DE HAAN 2003, DE HAAN & CLUCHIER 2005). Moreover, lack of significant sexual dimorphism in tail length seems to be generalized in the whole tribe, anyway for sure in Malpolon monspessulanus (DE HAAN 1999).

Picture from Bogert 1940.

Sexing these snakes is very difficult. One safe methode is taking a close look at the anal part of shed skins. See the pictures of the sheddings of some males on this site.

Broadley knew it back in 1959: "Sexual dimorphism. The sexes cannot be separated on scale counts. Sexing is made difficult by the small size of the hemipenes. The everted hemipenes of a 1466 mm. Essexvale males were only 12 mm. in length and 2 mm. in diameter.
 

 

Picture thanks to Cornélius de Haan

Dentition of Psammophiids, picture from Bogert 1940.

 

According to Cottone & Bauer 2009, sand snakes of the genus Psammophis consist of ~30 species in which species boundaries and taxonomic allocations have been widely disputed. Psammophis species are often the most common and conspicuous snakes throughout their ranges in Africa and Palearctic Asia. Unlike most snakes, psammophiids in tropical and temperate regions display little to no sexual size dimorphisme (SSD), exhibit little intrageneric variation in diet, and generally have low fecundities.


Further reading

A wonderful website about the herpetofauna of Ethiopia and adjacent territory can be found on www.herpetology-africa-ethiopia.com. The author is Vladimir Trailin. Many psammophiid snakes are treated there, with beautiful pictures.
The only problem is, that the website is in Csech, and not yet translated. However, I tried Google Translate with acceptable result, in my case in Dutch.