The giant flying squirrels (Petaurista) belong to the subfamily Sciurinae and are distributed from Pakistan and Nepal to East Asia, North Indochina and Southeast Asia. They are nocturnal small mammals primarily feed on fruits, flowers and branches, occasionally on eggs and insects. Attribute to the skin membrane between its legs, it could glide for rather long distance. There have been reports of distances up to 75 meters (250 ft.) or greater. The earliest record of flying squirrels was in the first Chinese dictionary “Erya”, and its excrement is the commonly adopted material in the history of traditional Chinese medicine.

So far, 43 diverse species and subspecies of the polymorphic genus Petaurista have been reported. Their highly variable external morphology has resulted in taxonomic discrepancies, and molecular phylogenetic studies have been limited by taxon sampling. Since 2000, scientists begin to try to clarify this controversial taxonomy by using molecular techniques. Most recently, in a study conducted by Dr. LI Song (Kunming Institute of Zoology, CAS) and his colleagues, 35 cytochrome b gene have been analyzed to reconstruct the phylogeny to obtain a more accurate picture of the evolutionary relationships, species differentiation and divergence pattern of Petaurista.

In LI’s present study, 4 major clades and 15 putative species have been recognized, which enable them to discuss the taxonomy of Petaurista at a preliminary level. By combing molecular phylogenetics with classical macrosystematics, the taxonomic status of P. marica, P. caniceps and P. sybilla have been discussed.

The results indicated that the P. caniceps is morphologically distinguishable from all other Petaurista by the absence of any unique white speckling over the back and a grey forehead. P. caniceps is sympatrically distributed with P. marica in southwestern China. And, it is noteworthy that the species from western and middle Yunnan, China are also genetically distinguishable and were identified as 2 putative species in species delimitation analyses. Meanwhile, P. marica and P. sybilla may have diverged from P. elegans 4.47 Ma and that the former 2 taxa split during the early to middle Pleistocene.

Furthermore, by using Bayesian relaxed molecular clock approaches and fossil data, the correlation between the evolutionary history of Petaurista and climate change has been analyzed. An estimation of the molecular divergence time demonstrated that the diversification and speciation of Petaurista began during the later Miocene and may have been affected by the uplifting of the Qinghai-Tibet plateau and subsequent climate change.

The main findings of this study have been published on PLoS ONE (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0070461).