Ninetine spiders in Brazilian Caatinga and Cerrado: revision of Kambiwa and description of Sertana gen. nov. (Araneae, Pholcidae), with analyses of predicted range shifts due to climate change

Among daddy long-legs spiders (Pholcidae), Ninetinae is a distinctive subfamily that comprises short-legged, fast-running spiders. Most species are small or tiny, lead reclusive lives, and are largely restricted to semiarid regions, which together has made them poorly collected and poorly known. Here, we build on focused recent collections in the Brazilian Cerrado and Caatinga biomes, two of the World’s richest tropical savanna, xeric shrubland and thorn forest regions. Our focus is on the taxonomy of the genus Kambiwa Huber, 2000 that previously contained only two nominal species, each known from a single locality. Combining morphological and molecular (CO1 barcode) data, we describe six new species in Kambiwa (K. brumado Huber sp. nov.; K. coribe Huber sp. nov.; K. ibo Huber sp. nov.; K. itacarambi Huber sp. nov.; K. maracas Huber sp. nov.; K. mucuge Huber sp. nov.), redescribe the type species K. neotropica (Kraus, 1957), and synonymize the monotypic genus Pemona Huber, 2019 with Kambiwa, resulting in the new combination K. sapo (Huber, 2019) comb. nov. In addition, we describe a new genus of superficially Kambiwa-like spiders from the same geographic region: Sertana Huber gen. nov., with five new species (S. bumba Huber gen. et sp. nov.; S. capivara Huber gen. et sp. nov.; S. igapora Huber gen. et sp. nov.; S. lapa Huber gen. et sp. nov.; S. sagarana Huber gen. et sp. nov.). In line with previous efforts to explore the processes underlying the geographical distribution of Ninetinae, we also evaluate the potential effects of future climate change on the environmental niche occupied by three selected species of Kambiwa. Our results corroborate previous findings that demonstrate an altitude-mediated response to climate change. For a highland species, areas of high habitat suitability almost disappear under more severe climate change scenarios. For two species with lowland records, the areas with high habitat suitability increase significantly. Finally, we analyze the male karyotype of K. ibo which consists of 28 chromosomes including a X1X2X3Y system. All chromosomes are biarmed except for the Y chromosome. This contribution concludes a series of publications on the subfamily Ninetinae. We use this opportunity to summarize current knowledge about the subfamily, to discuss open questions and knowledge gaps, and to suggest further research topics focusing on these tiny but exceptional pholcids.