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Mark G. Volkovitsh. 2019.
Larval morphology of the jewel beetles of the subfamily Polycestinae and its significance for the taxonomy and phylogeny (Coleoptera: Buprestidae).
Oral Presentation on: Immature Beetles Meeting 2019. October 3-4, Prague, Czech Republic.
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Slide 1. Larval morphology of the jewel beetles of the subfamily Polycestinae and its significance for the taxonomy and phylogeny (Coleoptera: Buprestidae) Mark G. Volkovitsh Slide 2. Buprestoidea and Polycestinae: Taxonomic compositions and species numbers Buprestidae is one of the largest coleopteran families counting about 15,300 species. Subfamily Polycestinae, which considered rather primitive, takes the 4th place in the family being significantly inferior to Agrilinae, Buprestinae and Chrysochroinae. It includes about 1300 species belonging to 13 tribes and 82 genera, among them 35 genera are monotypic and only 11 genera comprise more than 20 species, with 3 genera counting above 100 species; more than half of polycestine species belong to Acmaeoderini. Polycestine larvae demonstrate almost the entire spectrum of morpho-ecological and functional adaptations and evolutionary trends inherent in Buprestidae. Slide 3. Current state of knowledge of polycestine larvae The larvae of about 100 (8%) species from 24 (29.6%) genera and 11 tribes of Polycestinae have been described so far; the larvae of Perucolini and Bulini are still unknown; larvae of Acmaeoderini are best studied, while the larvae of other groups are known only for individual or very few species. The only larval key to buprestid higher taxa including Polycestinae was published by Cobos (1986). Larval characters of supraspecific taxa were analyzed by Volkovitsh & Hawkeswood (1999) and Volkovitsh & Bily (2015). Slide 4. Host plants of known polycestine larvae The vast majority of polycestine larvae develop on angiosperms. Associations of prospherioidtaxa Xyroscelidini, Prospheriniand Buliniwith such ancient relicsas Zamiaceaefrom Cycadophyta, Araucariacea and Podocarpaceae are most intriguing. Contrary to other Polyctesini,the species of Chrysophana group associated with gymnosperms. It is noteworthy that a number of polycestinespecies feeds on the plants characteristic ofmangrove communities. Feeding of Thryncopygini on Nolinaceae and leaf-mining Paratrachys on Ficusare regarded as most specialized. Slide 5. Morpho-ecological types of buprestid larvae General structure of buprestid larvae is determined by their habitats - either soil dwelling (schizopoid and julodoidmorpho-ecological types) or inside plant tissues (buprestoid, agriloid, and trachyoid types). Slide 6. Morpho-ecological types of polycestine larvae Polycestine larvae are predominantly buprestoid while the larvae of leaf-mining Paratrachysbelong to trachyoid type.Depending on the habitats (subcortical, xylophagous, grassy stem borers, etc.) and the hardness of the food substrate,several morpho-ecological subtypes distinguished within the buprestoid type. Leaf-miner trachyoid type occurs only in Polycestinae and Agrilinae. Slide 7. Diagnostic characters of Polycestinae larvae Polycestine larvae can be recognized by a complex of characters, of which a single pronotal groove (occurring also in Gabellinae and Agrilinae) and presence of additional lobe on stipes (except prospherioid genera) are most important. From Galbellinae they differ mainly by mouthpart structure, from Agrilinae - by presence of proventriculus, buprestoid spiracles and mouthparts. Slide 8. Phyletic lineages of Polycestinae Three phyletic lineages are established within Polycestinae: prospherioid, polycestioid, and acmaeoderioid. Slide 9. Fragment of phylogenetic tree for Polycestinae, Julodinae, Schizopodidae, outgroups based on molecular phylogenetic study The distinguishing ofpolycestioid and acmaeoderioid lineages is supported by molecular studies which in turn do not support the separation of prospherioid lineage from polycestioid one. The most strange thing is a position of Haplostethini as a sister group of Julodinaewhich according to the authors determines their rank of distinct subfamily. Slide 10. Prospherioid lineage Separation of presumably most primitive Gondwanianprospherioid lineageis supported only by absence of additional lobe on larval stipes (plesiomorphy). As seen on the phylogenetic tree, Xyroscelidini is sister to Thrincopygini + Chrysophana clade (though without a nodal support), while Astraeus is located in the base of polycestioid clade. Slide 11. Polycestioid lineage: Thryncopigini, Chrysophana-gr., Polyctesini Larval characters in part support the affinity of Thrincopygini and Polyctesini, while Chrysophana differs from all other genera of Polyctesini not only in larval morphology but also in host plants (Gymnosperms) and together with Beerelus deserves the separation in distinct tribe. Slide 12. Polycestioid lineage: Polycestini, Tyndarini Unique larval synapomorphies were found in all studied genera of Polycestini (paired sclerotized ring-shaped structures on the thoracic and 1st abdominal segment, multiple campaniformsensilla on mouth parts) and Tyndarini (expanded metathorax). Slide 13. Acmaeoderioid lineage: Ptosimini, Paratracheini Most primitive states are found in Ptosimini: Ptosima still retains microsetal areas on prementum, lackingin Sponsor. Larval characters and feeding habits conflict with a placement of Sponsor in Paratracheini, in the same time they support close relationship of Paratrachys with Ptosimini.In spite of extreme specialization resulting from leaf-minning habit, the larvae of Paratrachys retain many buprestoidstates such as proventriculus, spiracles, and mouthparts which never occur in the mining larvae of Tracheini (Agrilinae). Slide 14. Acmaeoderioid lineage: Acmaeoderini, Haplostethini Larvae of Acmaeoderina demonstrate the most advanced states of many characters, such as complete reduction of microsetal areas on labrum, prementum and integuments. Taxonomic position and relationship of Haplostethiniare still enigmatic. Despite of the results of molecular study,the larval morphology of Mastogenius is very similar to that of Polycestini and acmaeoderioid taxa what give grounds to treat Haplostethini as a member of Acmaeoderioid lineage or as belonging to a separate lineage within Polycestinae. Slide 15. Conclusions This study demonstrates a great importance of larval morphology for taxonomy and phylogenetics not only Polycestinae but entire Buprestoidea. Slide 16. Acknowledgements Slide 17. Thanks for your time!