Systematics of Nitidulinae (Coleoptera : Nitidulidae): phylogenetic relationships, convexity and the origin of phallalophagy

Nitiduline beetle genera of the Cyllodes complex are studied in the context of a phylogenetic analysis of 19 ingroup and eight outgroup taxa and 63 ch aracters derived from adult morphology and host relationship. In this analy sis, the Cyllodes complex is shown to be monophyletic. By eliminating the p roblematic taxon Camptodes and a priori weighting of the presence/absence o f procoxal rests, two monophyletic taxa are obtained within the Cyllodes co mplex (Cyllodes and Oxycnemus groups). A phylogenetic analysis of 13 termin al taxa represented by larval and adult semaphoronts shows a monophyletic C yllodes complex in one of two trees. The Cyllodes complex is formally recog nised as Cyllodini Everts, containing two or more monophyletic groups that are recognised on an informal basis. The Oxycnemus group is well supported and may include the enigmatic genus Camptodes. Taxonomic actions include tw o synonymies under Apsectochilus Reitter (= Meoncerus Sharp, syn. nov.; = L ordyrops Reitter, syn. nov.) and type species designations for Neotropical genera described by David Sharp (Apsectochilus, Eusphaerius, Mecyllodes, an d Somatoxus). Carinocyllodes, gen. nov. (type species: Eusphaerius lubricus Leschen & Carlton) is described and includes two additional species (C. be lli, sp. nov. and C. depressus, sp. nov.). Convexity is a character complex in nitidulids, and must be partitioned for phylogenetic reconstruction and character analysis. Two classes of charact er variation (dependent and independent) are discussed with regard to the e volution of convexity in the context of cladograms. A highly convex form wi th the capability to roll into a ball by tucking the head beneath the proth orax has evolved at least one or more times in Nitidulidae and several time s in unrelated beetle families. Fungal host-use patterns are highly concordant with the phylogenetic branch ing pattern in Cyllodini. Most members are associated with large-bodied Bas idiomycetes, with the exception of Camptodes which occurs on flowers and de velops in rotten vegetation. Most species of the Oxycnemus group are restri cted to Phallales, an obligate host pattern that is old relative to those a ssociations in the remaining Cyllodini that occur on other fungi. Another s ignificant shift occurred from phallalophagy to phytophagy if the hypothesi s is accepted that Camptodes is a member of the Oxycnemus group.