Abstract
The cryptic assassin bug subfamily Physoderinae is characterized by a distinctly uneven species and genus-level diversity across continents, but the lack of a phylogeny has so far precluded investigations into the biogeographic history of the group. Endemic Madagascan Physoderinae (11 of the 15 genera) exhibit broad morphological diversity, but the large (38 spp.) and seemingly uniform genus Physoderes is widely distributed across the Oriental and Australasian regions. The three remaining genera are small or even monotypic and restricted to the Neotropical (Cryptophysoderes, Leptophysoderes) and Afrotropical (Porcelloderes) regions. To investigate relationships among Physoderinae, with emphasis on the monophyly of the Madagascan fauna and the monophyly of Physoderes, we conducted a cladistic analysis based on 57 morphological characters and complete genus-level taxon sampling. We found that the Madagascan fauna is not monophyletic, indicating that the island was colonized more than once, although the great majority of Madagascan taxa are part of a single clade. Overall relationships are recovered as Afrotropical Porcelloderes + [(Neotropical Cryptophysoderes, Leptophysoderes) + (Madagascan, Oriental and Australasian taxa)]. Physoderes is shown to be polyphyletic and 3 new genera, Breviphysoderes gen. nov., Macrophysoderes gen. nov. and Nanophysoderes gen. nov., are erected to accommodate new species and several species previously classified as Physoderes. A taxonomic revision of Physoderes and allied genera is conducted. Diagnoses, updated distribution ranges, habitus and genitalic images, and identification keys are provided. A total of 17 synonymies are given, and 15 new species and 3 new genera are described, focusing on the diversity of Physoderinae in the Oriental and Australasian regions. The new species are Breviphysoderes fulvopicta gen. et sp. nov., B. tenebrosa gen. et sp. nov., Macrophysoderes cirripilosa gen. et sp. nov., M. elongata gen. et sp. nov., M. finisterre gen. et sp. nov., M. grandis gen. et sp. nov., Paraphysoderes popeye sp. nov., Physoderes anamalaiensis sp. nov., P. brevipennis sp. nov., P. minime sp. nov., P. muluensis sp. nov., P. mysorensis sp. nov., P. nigripennis sp. nov., P. ractepilosa sp. nov. and P. tricolor sp. nov.
Highlights
Clade A (Fig. 2) almost exclusively consists of Madagascan taxa, with the exception of Paraphysoderes popeye sp. nov., which we describe below as a new species from Papua New Guinea and which in our analysis is recovered as the sister taxon to the Madagascan species of Paraphysoderes Villiers, 1962
Divergences within the genus Physoderes were hypothesized to be as recent as 5 Mya
The nonmonophyletic nature of the Madagascan Physoderinae indicates that the evolutionary history of this group in the Madagascan region cannot be explained by a single colonization event with subsequent radiation
Summary
The reduviid subfamily Physoderinae is among the lesser-known groups of assassin bugs due to cryptic habits, restriction of most species to apparently small endemic ranges in wet-tropical areas of the Old and New Worlds, and the overall small number of genera and species compared to other reduviid subfamilies (Rédei 2012; Weirauch et al 2014): only 70 species classified into 15 genera are described to date (Maldonado 1990; Weirauch 2006; Davranoglou 2014; Davranoglou et al 2015). The physoderine fauna of Madagascar and the nearby Comoros Islands (11 genera with 29 spp.; Villiers 1962) shows considerable morphological diversity, with some taxa resembling assassin bugs in other subfamilies, such as Tribelocephaloides Villiers, 1962 and Mimoelasmodema Villiers, 1962, that superficially resemble Tribelocephalini (in the subfamily Ectrichodiinae) and Elasmodeminae, respectively (Villiers 1962; Weirauch et al 2014; Forthman & Weirauch 2017; Fig. 2). But morphologically relatively uniform, the Oriental and Australasian fauna of Physoderinae comprises 38 species currently classified within a single genus – Physoderes Westwood, 1845 (Maldonado 1990; Cao et al 2011; Chlond 2011). Villiers (e.g., 1962, 1968) described the majority of the physoderine diversity in Madagascar during the 1950s and 1960s, and Miller (e.g., 1940, 1941) described the Oriental and Australasian Physoderes species in South-East Asia and the Pacific from the 1940s to the 1960s
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