A New Species of the Genus Rhabdophis Fitzinger,1843(Squamata:Colubridae)in Southwestern Sichuan,China

The genus Rhabdophis is a group of widely distributed snakes with more than 20 species.Recent field surveys uncovered a species in southwestern China,which has long been considered as R.pentasupralabialis.Combined molecular and morphological analyses revealed it as a new species Rhabdophis chiwen sp.nov.Based on 12 specimens,this new species is distinguished by the following characters:1)dorsal body saddlebrown,dorsal scales typically with black margins forming spots and stripes,the margin of the outer row forming two faint dorsolateral black cross-bars alongside body;2)ventral scales 151–159,the outer margin of ventral scales and several lateral rows of dorsal scales forming ventrolateral longitudinal brownish-red coloration,with faint black spots in the middle of ventral scales;3)a black oblique stripe present below eyes,often with a black spot between the 2 nd and 3 rd supralabial and a black stripe on the 5 th supralabial;4)eyes dark khaki,pupils black;5)infralabials usually 7,the first four in contact with anterior chin-shields;6)temporal scales 1+1;7)dorsal scales in 15 rows,feebly keeled except the outer 1–2 rows;8)anal scale divided;subcaudals 45–59;9)preocular 1 and postoculars 3(occasionally 2);10)body medium-sized(snout-vent length:adult males 404–431 mm,adult females 409–476 mm);11)tail moderate(tail length/total length in adult males 0.205–0.238,in adult females0.172–0.193).With the discovery of this new species,the total number of species in genus Rhabdophis is 28 with 12 th species known to occur in China.

Do predators prefer toxic animals?A case of chemical discrimination by an Asian snake that sequesters firefly toxins

Several Asian natricine snakes of the genus Rhabdophis feed on toads and sequester steroidal cardiac toxins known as bufadienolides(BDs)from them.A recent study revealed that species of the Rhabdophis nuchalis Group ingest lampyrine fireflies to sequester BDs.Although several species of fireflies are distributed in the habitat of the R.nuchalis Group,only lampyrine fireflies,which have BDs,are included in the diet of these snakes.Thus,we hypothesized that the R.nuchalis Group chemically distinguishes fireflies that have BDs from those that do not have BDs.We also predicted that the R.nuchalis Group detects BDs as the chemical cue of toxin source.To test these predictions,we conducted 3 behavioral experiments using Rhabdophis chiwen,which belongs to the R.nuchalis Group.In the first experiment,R.chiwen showed a moderate tongue flicking response to cinobufagin,a compound of BDs.On the other hand,the snake showed a higher response to the chemical stimuli of lampyrine fireflies(BD fireflies)than those of lucioline fireflies(non-BD fireflies).In the second experiment,in which we provided live BD and non-BD fireflies,the snake voluntarily consumed only the former.In the third,a Y-maze experiment,the snake tended to select the chemical trail of BD fireflies more frequently than that of non-BD fireflies.These results demonstrated that R.chiwen discriminates BD fireflies from non-BD fireflies,but the prediction that BDs are involved in this discrimination was not fully supported.To identify the proximate mechanisms of the recognition of novel toxic prey in the R.nuchalis Group,further investigation is necessary.