Old Lineage on an Old Island: Pixibinthus, a New Cricket Genus Endemic to New Caledonia Shed Light on Gryllid Diversification in a Hotspot of Biodiversity

Abstract

Few studies have focused on the early colonization of New Caledonia by insects, after the re-emergence of the main island, 37 Myr ago. Here we investigate the mode and tempo of evolution of a new endemic cricket genus, Pixibinthus, recently discovered in southern New Caledonia. First we formally describe this new monotypic genus found exclusively in the open shrubby vegetation on metalliferous soils, named ‘maquis minier’, unique to New Caledonia. We then reconstruct a dated molecular phylogeny based on five mitochondrial and four nuclear loci in order to establish relationships of Pixibinthus within Eneopterinae crickets. Pixibinthus is recovered as thesister clade of the endemic genus Agnotecous, mostly rainforest-dwellers. Dating results show that the island colonization by their common ancestor occurred around 34.7 Myr, shortly after New Caledonia re-emergence. Pixibinthus and Agnotecous are then one of the oldest insect lineages documented so far for New Caledonia. This discovery highlights for the first time two clear-cut ecological specializations between sister clades, as Agnotecous is mainly found in rainforests with 19 species, whereas Pixibinthus is found in open habitats with a single documented species. The preference of Pixibinthus for open habitats and of Agnotecous for forest habitats nicely fits an acoustic specialization, either explained by differences in body size or in acoustic properties of their respective habitats. We hypothesize that landscape dynamics, linked to major past climatic events and recent change in fire regimes are possible causes for both present-day low diversity and rarity in genus Pixibinthus. The unique evolutionary history of this old New Caledonian lineage stresses the importance to increase our knowledge on the faunal biodiversity of ‘maquis minier’, in order to better understand the origin and past dynamics of New Caledonian biota.

In and out of the Neotropics: historical biogeography of Eneopterinae crickets

“…Centuriarus and Gnominthus form a clade located between the paraphyletic Lebinthus and the clade ( Agnotecous , Pixibinthus ), also found in Anso et al . (). The genus Swezwilderia , previously considered as Eneopterinae incertae sedis (Robillard & Desutter‐Grandcolas, ), is confirmed within the tribe Lebinthini, as suggested by previous studies (Nattier et al ., ; Chintauan‐Marquier et al ., ).…”

Ten false ideas about New Caledonia biogeography

“…Second, to perform decisive tests, we need to carefully consider a relevant and accurate taxonomic or geographical sample (e.g. Nattier et al, 2011;Swenson et al, 2014;Anso et al, 2016;Skipwith et al, 2016). Sampling accuracy often needs to be improved by long field and taxonomic studies (Najt and Matile, 1997;Najt and Grandcolas, 2002;Grandcolas, 2008Grandcolas, , 2009Guilbert et al, 2014).…”

Phylogenetic relationships in the cricket tribe Xenogryllini (Orthoptera, Gryllidae, Eneopterinae) and description of the Indian genusIndigryllusgen. nov.

“…The tribe Xenogryllini is composed of three genera and 12 valid spe- For outgroup selection, we referred to a previous study (Anso et al, 2016) and selected eight species representing all five tribes of the Eneopterinae subfamily, as well as two more distant species belonging to the subfamily Gryllinae. Whenever possible, we obtained DNA sequence data from the same previous voucher specimens.…”