Phylogenetics and biogeography of the endemic Madagascan millipede assassin bugs (Hemiptera: Reduviidae: Ectrichodiinae)

Abstract

For at least the past 80my, Madagascar, a major biodiversity hotspot, has been isolated from all other landmasses. This long-term isolation, along with geologic and climatic factors within Madagascar and throughout the Indian Ocean, has undoubtedly influenced the evolution of the island's biota. However, few systematic analyses incorporating modern divergence dating and biogeographic analyses have focused on Madagascan insects. The diverse Madagascan millipede assassin bugs (Heteroptera: Reduviidae: Ectrichodiinae) offer an opportunity to contribute to a limited body of insect-related research that explores Madagascar's historical biogeography. A molecular dataset (COI mtDNA and 18S, 28S D2 and D3-D5 rDNAs) for 56 taxa (39 ingroup) and a combined morphological (145 characters) and molecular dataset for 110 taxa (93 ingroup) are analyzed with maximum likelihood (ML) and parsimony approaches. Based on the molecular ML phylogeny, divergence times were estimated using fossil and secondary calibrations and biogeographic analyses performed using DIVA, DEC, and DEC+j models to determine the role and patterns of vicariance and dispersal in the origin of Madagascan Ectrichodiinae. Results indicate that Ectrichodiinae in Madagascar do not form a monophyletic group, different clades are closely related to Afrotropical and Oriental lineages, and have colonized the island via transoceanic dispersal at least twice from the Oriental region and once from the Afrotropical region in the last ∼68my. Additionally, the DEC+j and DIVA models infer a single out-of-Madagascar dispersal event to the Afrotropical region. Oceanic and geologic factors that may have facilitated dispersal between these three regions are discussed. Results of the combined analyses are used to explore character support for Madagascan taxa and inform taxonomic diagnoses. Our results are congruent with the small but growing body of biogeographic research supporting Cenozoic transoceanic dispersal for Madagascan invertebrates to and from Oriental and Afrotropical regions.

Uncovering hidden biodiversity: phylogeny and taxonomy of Physoderinae (Reduviidae, Heteroptera), with emphasis on Physoderes Westwood in the Oriental and Australasian regions

“…Finally, it also remains to be tested whether the Madagascan Physoderinae are monophyletic, representing a single clade and potentially therefore a radiation in adaptation to different habitats or other biotic or abiotic factors. Alternatively, the Madagascan fauna might represent several unrelated lineages, as recently shown for the assassin bug subfamily Ectrichodiinae (Forthman & Weirauch 2016). …”

Millipede assassins and allies (Heteroptera: Reduviidae: Ectrichodiinae, Tribelocephalinae): total evidence phylogeny, revised classification and evolution of sexual dimorphism

“…A total of 16 terminals lacked information on male morphology because the males remain unknown or the species could not be determined. Despite the possibility of extreme sexual dimorphism in these 16 terminals, we follow Forthman & Weirauch () and infer only male morphological characters that are probably static between males and females (e.g. antennal segmentation, relative lengths of labial segments, scutellar apical processes, etc.)…”

“…Furthermore, the recently described genus Tribelocodia shows a mix of characters thought to be diagnostic for both Ectrichodiinae and Tribelocephalinae, and was recovered as part of the Tribelocephalinae in that analysis. More recently, phylogenetic hypotheses in Forthman & Weirauch (), based on separate and combined morphological and molecular data, supported the monophyly of both subfamilies in most analyses, but Ectrichodiinae were rendered paraphyletic with respect to Tribelocephalinae in the parsimony analyses on the molecular dataset. None of the published analyses included an extensive sample of the genus‐level diversity of Ectrichodiinae and Tribelocephalinae, and only Forthman & Weirauch () combined morphological and molecular data.…”

“…More recently, phylogenetic hypotheses in Forthman & Weirauch (), based on separate and combined morphological and molecular data, supported the monophyly of both subfamilies in most analyses, but Ectrichodiinae were rendered paraphyletic with respect to Tribelocephalinae in the parsimony analyses on the molecular dataset. None of the published analyses included an extensive sample of the genus‐level diversity of Ectrichodiinae and Tribelocephalinae, and only Forthman & Weirauch () combined morphological and molecular data. A densely sampled, well‐resolved and well‐supported phylogeny of Ectrichodiinae and Tribelocephalinae is key to investigating the evolution of sexual dimorphism in this group.…”

“…Despite the diversity of sexually dimorphic characters and the size of the group, which make Ectrichodiinae a compelling study system, investigations into the evolution of sexual dimorphism are currently impeded by a lack of comprehensive phylogenetic hypotheses for this group. Recent morphological and molecular phylogenetic or phylogenomic analyses of Reduviidae incorporated few representatives of Ectrichodiinae (Weirauch, , ; Weirauch & Munro, ; Hwang & Weirauch, ; Zhang et al ., ), except for a combined morphological and molecular analysis that focused on Madagascan Ectrichodiinae (Forthman & Weirauch, ). These studies support Ectrichodiinae (or part thereof; see later) as the sister taxon to Tribelocephalinae, a moderate‐sized subfamily (150 species, 16 genera) that comprises mostly cryptically coloured species that display little sexual dimorphism (Maldonado, , ; Rédei, ; Weirauch, ; Ishikawa et al ., ; Davranoglou, ; Weirauch et al ., ).…”