Taxonomic Revision of the Genus Miltotranes Zimmerman, 1994 (Coleoptera: Curculionidae: Molytinae), the Bowenia-Pollinating Cycad Weevils in Australia, with Description of a New Species and Implications for the Systematics of Bowenia.

Abstract

Simple SummaryMiltotranes Zimmerman, 1994 is a genus of weevils pollinating Bowenia cycads belonging to two small endemic Australian species included in the IUCN Red List of Threatened Species and CITES Appendix II. We provide the first taxonomic revision of Miltotranes resulting in the identification of two previously described species and a newly recognised species, M. wilsoni sp. n. from the McIlwraith Range of the Cape York Peninsula. Morphological comparison reveals its affinity to Tranes, whose species are the pollinators of Macrozamia and Lepidozamia cycads. It appears that the association of Miltotranes with Bowenia may represent a secondary host switch in the Tranes group due to a closer relationship between Macrozamia, Lepidozamia and African Encephalartos than with Bowenia. The coincidence of the geographic ranges of Miltotranes weevils with distribution of their cycad hosts indicates that the isolated Bowenia population in the McIlwraith Range may represent a distinct, third species of Bowenia. Likely, the conspecificity of the Miltotranes weevils occurring in the Wet Tropics also suggests that several morphologically enigmatic localised populations represent B. spectabilis, confirming earlier botanical conclusions. The present study highlights the significance of systematic study of tightly plant-associated insects and its relevance for the taxonomy of their host plants.The Australian endemic weevils of the genus Miltotranes Zimmerman, 1994 (Curculionidae: Molytinae: Tranes group), comprising two species, M. prosternalis (Lea, 1929) and M. subopacus (Lea, 1929), are highly host-specific and the only known pollinators of Bowenia cycads, which comprise two CITES-protected species restricted to Tropical Queensland in Australia. In the present study, the taxonomy of Miltotranes is reviewed, a lectotype for the name Tranes prosternalis Lea, 1929 is designated and a new species associated with the Bowenia population in the McIlwraith Range is described as M. wilsoni sp. n. The descriptions and diagnoses of all species are supplemented with illustrations of their habitus and salient structures, and an identification key to all species and a distribution map are provided. Potential implications of the new species and of the taxonomy and biogeography of Miltotranes overall on the systematics and conservation of Bowenia are discussed.