Dipsas incerta (JAN, 1863)
Can you confirm these amateur observations of Dipsas incerta?
|Higher Taxa||Colubridae (Dipsadinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||Jan's Snail-eater|
|Synonym||Leptognathus incertus JAN 1863: 101|
Dipsas incerta — PARKER 1935
Dipsas incerta — PETERS & OREJAS-MIRANDA 1970: 86
Dipsas incerta — PASSOS et al. 2004
Dipsas incerta — WALLACH et al. 2014: 232
|Distribution||French Guiana, Suriname, Guiana, Brazil (Espirito Santo to Santa Catarina; Rio Grande do Sul, Rio de Janeiro)|
Type locality: “Gujana francese” (= French Guiana) but this record was disputed by Peters (1960).
|Types||Holotype: lost; originally MSNM (Milano), Department of Ornithology of the Museo Civico di Storia Naturale, Milano, Italy but destroyed during the Second World War (PASSOS et al. 2004). Neotype: BMNH 1922.214.171.124 (formerly 126.96.36.1999), adult male, SVL 435 mm, TL 215 mm, obtained from the collection of Dr. Van Lidth de Jeude, Surinam (neotype designation by Passos 2004 invalid fide Harvey 2008).|
|Comment||Synonymy: Leptognathus alternans FISCHER 1885 has been removed from the synonymy of D. incerta by PASSOS et al. (2004). D. copei has been synonymized with D. incerta by PASSOS et al. 2004 and revalidated by HARVEY 2008. The neotype designated by PASSOS et al. (2004) is invalid fide HARVEY 2008.|
Characters: According to Jan (1863) and Jan and Sordelli (1870), the holotype of L. incertus possesses 15 dorsal scales rows, vertebral row approximately twice as large as adjacent scales; loreal enters the orbit; 1 preocular; 2 postoculars; no subocular; temporals 2 + 3 + 2; 9 supralabials, fourth to sixth in contact with the orbit; infralabials 10 on both sides, first pair in contact behind the symphisial; first to fifth pair touch the first pair of genials; fifth and sixth touch the second pair of genials; number of pairs of genials 3 or 4.
Boulenger (1896) provided a key to the species of the genus Leptognathus. According to this key, L. alternans and L. incertus differ in the number of ventrals, subcaudals, and preocular scales. Leptognathus alternans (male; n = 1) has 197 ventrals, 110 subcaudals, and 2 preoculars scales, while L. incertus (male; n = 1) has 204 ventrals, 122 subcaudals, and 1 preocular scale. The specimen of L. alternans examined by Boulenger (1896) was the holotype, while the specimen associated with L. incertus was from São José dos Campos, State of São Paulo. The colour patterns described by Boulenger (1896) for these two specimens are quite similar, the differences being easily acceptable as falling within normal intraspecific variation. The same interpretation can be used to justify the differences in the pholidosis of the specimens.
Distribution: not in Venezuela (Luis Esqueda, pers. comm., 21 April 2016, see also Natera-Mumaw et al. 2015).