Where are they from and where are they going? Detecting areas of endemism, distribution patterns and conservation status of the order Spirostreptida in Brazil (Diplopoda, Juliformia)

Abstract

Millipedes are well-known for their limited dispersal abilities with species restricted to mountains, islands, and patches of forest being important models for formulating and testing biogeographic hypotheses. The order Spirostreptida is composed of nearly 1300 species distributed across the Afrotropical, Oriental, and Neotropical regions. The order is divided into the suborders Cambalidea and Spirostreptidea with the families Pseudonannolenidae (Cambalidea) and Spirostreptidae (Spirostreptidea) occurring in Brazil. To date, there have been no studies on the biogeography of Neotropical Spirostreptida. We employed a multi-approach analysis with Parsimony Analysis of Endemicity, Endemicity Analysis, and Infomap, to detect areas of endemism and patterns of distribution of the order in Brazil. Six areas of endemism are proposed for the 133 Brazilian species: Northern Serra Geral, Southeastern mountain ranges, Cerrado and Atlantic Forest zone, Eastern Cerrado and Serra do Espinhaço, Pantanal, and Southern Amazon and Cerrado zone. Most endemic areas fall within the Atlantic Forest, which has been previously shown to be an important area of endemism for many invertebrate taxa. The richest biomes are the Atlantic Forest with 75 species and the Cerrado with 55 species, while the least rich biomes are the Caatinga with six species and the Pampa with three species. Although the southeastern region of Brazil has the highest species richness, it also has the highest concentration of threatened species. Based on International Union for Conservation of Nature (IUCN) criteria, most Brazilian Spirostreptida are either endangered or critically endangered, with the highest concentration of endangered taxa occurring in the Atlantic Forest biome.