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Background Meligethes are pollen-beetles associated with flowers of Rosaceae as larvae. This genus currently consists of 63 known species in two subgenera, Meligethes and Odonthogethes, predominantly occurring in the eastern Palaearctic. We analyzed 74 morphological and ecological characters (169 states) of all species, as well as of 11 outgroup species from 7 Meligethinae genera (including Brassicogethes), to investigate their phylogeny. We also conducted a parallel molecular analysis on 9 Meligethes, 9 Odonthogethes, 3 Brassicogethes and 2 Meligethinus species based on DNA sequence data from mitochondrial (COI, 16S) and nuclear (CAD) genes. Results Morphological phylogenetic reconstructions supported the monophyly of the whole genus and clades corresponding to purported subgenera Meligethes s.str. and Odonthogethes. Main species-groups were mostly confirmed, however some unresolved polytomies remained. Molecular data placed members of Brassicogethes (including 42 mostly W Palearctic species associated with Brassicaceae) as sister to Odonthogethes, with this clade being sister to Meligethes s.str. This phylogenetic scenario suggests that monophyletic Meligethes s.str., Odonthogethes and Brassicogethes should be regarded alternatively as three subgenera of a monophyletic Meligethes, or three genera in a monophyletic genus-complex, with mutually monophyletic Brassicogethes and Odonthogethes. Molecular analyses estimated the origin of this lineage at ca. 14–15 Mya from a common stem including Meligethinus. Conclusions We hypothesize that the ancestor of Meligethes specialized on Rosaceae in the Middle Miocene (likely in Langhian Age) and subsequently radiated during Late Miocene and Plio-Pleistocene maintaining a trophic niche on this plant family. This radiation was primarily due to geographic isolation in E Asiatic mountain systems. Combined evidence from morphology, ancestral state parsimony reconstruction of host-plant associations and molecular evidence suggested that Rosoideae (Rosa spp.) represented the ancestral hosts of Meligethes s.str., followed by an independent shift of ancestral Odonthogethes (ca. 9–15 Mya) on Rubus (Rosoideae) and members of Rosaceae Spiraeoideae. Other ancestral Odonthogethes probably shifted again on the unrelated plant family Brassicaceae (maybe 8–14 Mya in S China), allowing a rapid westward radiation of the Brassicogethes clade.

The genus Meligethinus Grouvelle, 1906 represents a small group of pollen beetles, including some twenty species distributed from southern Palaearctic areas to northern Oriental and Afrotropical regions. All constituent species appear to be strictly associated as larvae and adults to male inflorescences of palms (Monocots: Arecaceae). Two new species of this genus (Meligethinus mondlanei sp. nov. and M. hamerlae sp. nov.) were recently discovered in southern Mozambique, and are described herein. Both are associated as larvae with male inflorescences of the widespread eastern African palm Phoenix reclinata Jacq. The two new species are compared with related taxa from central Africa. Additionally, the presence of additional species of the same genus in southern Mozambique is reported, and the local associations of several Meligethinus species are discussed.

Five new species of the genus Lamiogethes Audisio & Cline are described from western, central and southern China: L. falcatus sp. n. (Sichuan), L. hastipenis sp. n. (Hubei), L. sagittalis sp. n. (Shaanxi), L. unditibiis sp. n. (Chongqing), and L. limaelytralis sp. n. (Sichuan). The first four new species appear to be morphologically related to Lamiogethes ancestor (Kirejtshuk, 1980) (comb. n.) from Central China, and allied taxa. Lamiogethes limaelytralis sp. n. appears to be more isolated, probably with relationships to the recently described L. forcipenis Liu, Huang, Cline & Audisio, 2017 and L. convexistrigosus Liu, Huang, Cline & Audisio, 2017 from Sichuan. All new species differ from other closely related taxa by details of the body shape and color, as well as the shape of the male and/or female genitalia.

Four new species of Meligethes Stephens, 1830, M. (s.str.) macrofemoratus (Shaanxi, Ningxia), M. (s.str.) yak (NW Sichuan), M. (s.str.) auropilosus (Tibet) and M. (Odontogethes) aurorugosus (Tibet) spp. nov., are described and illustrated from China. Diagnostic characters distinguishing these new species from closely related taxa are discussed. The previously unknown male of Meligethes (s.str.) aureolineatus Audisio, Sabatelli & Jelinek, 2015 from Sichuan and the previously unknown female of M. (Odontogethes) scrobescens Chen, Lin, Huang & Yang, 2015 from Sichuan are also described. Additional data are also presented on the geographic distribution and life history of other Chinese Meligethes species.

One new species, Cyllodes quinquemaculatus Liu, Yang & Huang, sp. nov., one newly recorded species, Cyllodes accentus Kirejtshuk, 1985, from China and one previously known species, Cyllodes bifascies (Walker, 1859), are described. Photos of their habitus, antenna, mouthparts, and genitalia are provided. A species checklist of Cyllodes from China is presented.