A cladistic analysis reveals an eastern Tibetan occurrence ofTaiwanoserica(Coleoptera: Scarabaeidae)

Abstract

Abstract. The systematic position of some newly discovered Serica species from the eastern margin of the Tibetan Plateau (Sichuan, China) is explored through a phylogenetic analysis based on 117 morphological characters using the parsimony criterion. The resulting consensus tree of this analysis reveals that three of these taxa belong to the lineage of Taiwanoserica as supposed initially due to their general external appearance. Based on the occurrence of related taxa and on the topology of Taiwanoserica taxa as well, it must be assumed that Taiwanoserica originated also in the eastern Tibetan mountains. Four new species are described: Serica (sensu lato) silviae n. sp., Serica (Taiwanoserica) wenchuanensis n. sp., Serica (Taiwanoserica) sigipinensis n. sp., Serica (Taiwanoserica) chengtuensis n. sp.Resumé. Une analyse cladistique révèle une occurence est-tibétaine de Taiwanoserica (Coleoptera : Scarabaeidae). La position systématique d'espèces du genre Sericea, nouvellement découvertes à la bordure est du Plateau Tibétain (Sichuan, Chine), est déterminée par l' étude phylogénétique en parsimonie basée sur l'analyse de 11 caractères morphologiques. L'arbre de consensus qui résulte de cette analyse montre que trois de ces taxons appartiennent à la lignée des Taiwanoserica comme suggéré initialement par leur apparence morphologique externe. A partir de la distribution des taxons de Taiwanosericea et des taxons proches, on peut supposer que ce genre est originaire de l'est de la chaîne tibétaine. Quatre nouvelles espèces sont décrites : Serica (sensu lato) silviae n. sp., Serica (Taiwanoserica) wenchuanensis n. sp., Serica (Taiwanoserica) sigipinensis n. sp., Serica (Taiwanoserica) chengtuensis n. sp. Beside the Japanese archipelago, Taiwan is for Scarabs one of the best explored regions in East Asia. Due its richness of endemism and huge biodiversity due to the altitudinal and climatological variety it have been also an attractive object for biogeography (e.g. Mey 1997;Choi 2000;Lin et al. 2002). Th is study of the chafer group Taiwanoserica Nomura1974 illustrates, indeed, how much species classifi cation and biogeographical investigation of Taiwan's fauna rely on the exploration of the so far only poorly studied neighbouring areas of East and South-East Asia . Taiwanoserica was established for a couple of species (Nomura 1974), which was believed so far to be entirely endemic to Taiwanese archipelago even after numerous taxa have been discovered additionally (Kobayashi 1983;1988;1993;Kobayashi & Yu 2000;Ahrens 2002). Currently it contains 20 species inhabiting all the higher elevations in Taiwan. Recently it has been shown (Ahrens 2007a) that they are very closely related to the genus Serica MacLeay 1819. In consequence of its systematic position between clades assigned so far to Serica, Taiwanoserica was downgraded to a subgenus of Serica (Ahrens 2007b). Among a rich material that I received form the Smithsonian Institution (USNM) for identifi cation four new forms have been discovered from Sichuan. Th ese indiv...