Melanesia holds the world’s most diverse and intact insular amphibian fauna

Abstract

Identifying hotspots of biological diversity is a key step in conservation prioritisation. Melanesia—centred on the vast island of New Guinea—is increasingly recognised for its exceptionally species-rich and endemic biota. Here we show that Melanesia has the world’s most diverse insular amphibian fauna, with over 7% of recognised global frog species in less than 0.7% of the world’s land area, and over 97% of species endemic. We further estimate that nearly 200 additional candidate species have been discovered but remain unnamed, pointing to a total fauna in excess of 700 species. Nearly 60% of the Melanesian frog fauna is in a lineage of direct-developing microhylids characterised by smaller distributions than co-occurring frog families, suggesting lineage-specific high beta diversity is a key driver of Melanesian anuran megadiversity. A comprehensive conservation status assessment further highlights geographic concentrations of recently described range-restricted threatened taxa that warrant urgent conservation actions. Nonetheless, by world standards, the Melanesian frog fauna is relatively intact, with 6% of assessed species listed as threatened and no documented extinctions; and thus it provides an unparalleled opportunity to understand and conserve a megadiverse and relatively intact insular biota.

A new species of torrent-breeding treefrog (Pelodryadidae: Litoria) from the mountains of Papua, Indonesia, with new records and observations of Litoria dorsivena (Tyler, 1968)

“…Species in the group show a great diversity in body size, form and ornamentation, degree of sexual-size dimorphism and potentially also the extent to which they are tied to stream environments throughout their lives (Günther and Richards 2005). We are aware of at least 15 other candidate species in this guild, and we emphasise that large areas of New Guinea remain undersurveyed, especially in Indonesia (Oliver et al 2022). Given precipitous declines in high-elevation torrent-breeding Litoria in nearby Australia (Bower et al 2017), cryptic extinction risk (i.e., where knowledge gaps and predictors of vulnerability overlap: McDonald et al 2022) is an important issue for this clade.…”

“…Given precipitous declines in high-elevation torrent-breeding Litoria in nearby Australia (Bower et al 2017), cryptic extinction risk (i.e., where knowledge gaps and predictors of vulnerability overlap: McDonald et al 2022) is an important issue for this clade. In this context, documenting and understanding the diversity of this fascinating radiation is a high research priority for Melanesian frogs (Oliver et al 2022).…”

“…The mountains of New Guinea are home to a diverse and highly endemic frog biota (Menzies 2006;Oliver et al 2022). One prominent component of these upland biotas consists of approximately 20 species of torrent-breeding treefrogs in the family Pelodryadidae that most workers in Melanesia currently ascribe to the genus Litoria (Menzies 2006;Richards et al 2021).…”

A new species of insular treefrog in the Litoria thesaurensis species group from the Nakanai Mountains, New Britain, Papua New Guinea

“…The frog fauna of East Melanesia shows a particularly marked differentiation from that of nearby mainland New Guinea, being dominated by a single radiation of direct-developing species in the family Ceratobatrachidae that has diversified greatly in ecology and associated body form (Menzies 2006;Brown et al 2015;Oliver et. al.…”

“…In contrast, the two frog families that dominate on nearby New Guinea are depauperate in East Melanesia (Menzies 2006). There are just two species of Microhylidae (both endemic to New Britain), while there are probably over 400 species in this radiation on New Guinea (Oliver et. al.…”