The phylogeny of the genus Lasioserica inferred from adult morphology - implications on the evolution of montane fauna of the south Asian orogenic belt (Coleoptera: Scarabaeidae: Sericini)

Abstract

The species of Lasioserica are highly diversified within the south Asian orogenic belt, such as the Himalaya, south-eastern Tibet and the mountains of northern Indochina. The study presents a preliminary phylogeny of Lasioserica based on adult morphology. Sixty-one species were examined for the cladistic analysis based on parsimony using successive approximations weighting and including 84 characters. As a result of the phylogenetic hypothesis on Lasioserica elaborated here, the taxonomic definition of Lasioserica and the validity of Amiserica are questionable and need to be revised. Taxonomic conclusions are here limited so far to the genus assignment of Amiserica antennalis (Nomura 1974) comb. n. The cladistic analysis revealed a large monophyletic clade of Lasioserica containing almost all species assigned to this group so far. Among this monophylum the following pattern have become evident: (1) a number of ancestral lineages from the eastern Himalaya and Indochina, (2) a large clade with almost exclusively Himalayan species and (3) one clade with only Chinese and Indochinese taxa. Based on this topology we may suggest that the more recent evolution of Lasioserica was more independent in these two major regions (Himalaya/Indochina). There is comparatively good evidence from range positions of closely related species for allopatric geographical speciation in Lasioserica with the majority of closely related central Himalayan species occurring allopatrically or parapatrically. The tree topology does not permit conclusions whether speciation progressed more often from east to west or vice versa. More easterly distributed lineages in the Himalaya seem to contrast this pattern with a greater part of closely related species occurring sympatrically. Since cumulative ranges of the major lineages of the Himalayan clade overlap in all respects, diversification of the almost strictly Himalayan clade of Lasioserica should be attributed to a rather long and persistent evolution within the Himalaya.