Biogeographic patterns and diversification dynamics of the genus Cardiodactylus Saussure (Orthoptera, Grylloidea, Eneopterinae) in Southeast Asia

Abstract

Southeast Asia harbors an extraordinary species richness and endemism. While only covering 4% of the Earth's landmass, this region includes four of the planet's 34 biodiversity hotspots. Its complex geological history generated a megadiverse and highly endemic biota, attracting a lot of attention, especially in the field of island biogeography. Here we used the cricket genus Cardiodactylus as a model system to study biogeographic patterns in Southeast Asia. We carried out molecular analyses to: (1) infer phylogenetic relationships based on five mitochondrial and four nuclear markers, (2) estimate divergence times and infer biogeographical ancestral areas, (3) depict colonization routes, and summarize emigration and immigration events, as well as in situ diversification, and (4) determine whether shifts in species diversification occurred during the course of Cardiodactylus evolution. Our results support the monophyly of the genus and of one of its species groups. Dating and biogeographical analyses suggest that Cardiodactylus originated in the Southwest Pacific during the Middle Eocene. Our reconstructions indicate that Southeast Asia was independently colonized twice during the Early Miocene (ca. 19-16 Million years ago), and once during the Middle Miocene (ca. 13 Million years ago), with New Guinea acting as a corridor allowing westward dispersal through four different passageways: Sulawesi, the Philippines, Java and the Lesser Sunda Islands. Sulawesi also served as a diversification hub for Cardiodactylus through a combination of high immigration and in situ diversification events, which can be accounted for by the complex geological history of the Wallacea region.

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

“…The Xenogryllini are mostly distributed in continental regions, except for X. marmoratus which is found both in continental Asia (China, South Korea) and in islands of Japan, China (Taiwan, Hainan) and Sri Lanka (Figure ). In contrast, the Lebinthini fully express their species diversity when they are distributed in islands (e.g., Desutter‐Grandcolas & Robillard, ; Nattier et al, ; Dong et al, ). As a consequence, the two tribes only barely overlap in their marginal distributions in coastal regions of China and Japan, where a few Lebinthini occur in sympatry with X. marmoratus .…”

“…In contrast, very high rates of speciation have been demonstrated in crickets distributed on islands (Mendelson & Shaw, ). The Lebinthini species living on islands are most often found in forested areas; they also usually have more restricted distributions, which could in turn promote higher rates of speciation (Dong et al, ). These differences could partly explain the imbalance of diversity observed between the two tribes.…”

“…The Xenogryllini are mostly distributed in continental regions, except for X. marmoratus which is found both in continental Asia (China, South Korea) and in islands of Japan, China (Taiwan, Hainan) and Sri Lanka (Figure 8). In contrast, the Lebinthini fully express their species diversity when they are distributed in islands (e.g., Nattier et al, 2012;Dong et al, 2018 (Mendelson & Shaw, 2005). The Lebinthini species living on islands are most often found in forested areas; they also usually have more restricted distributions, which could in turn promote higher rates of speciation .…”

“…The crickets of the subfamily Eneopterinae have been studied for the diversity of their communication signals and related structures (e.g., Robillard & Desutter‐Grandcolas, ; Robillard & Desutter‐Grandcolas, ; Robillard, Montealegre‐Z, Desutter‐Grandcolas, Grandcolas, & Robert, ; ter Hofstede, Schoneich, Robillard, & Hedwig, ; Schneider, Römer, Robillard, & Schmidt, ) and for their biogeographical patterns (Dong et al, ; Nattier, Robillard, Desutter‐Grandcolas, Couloux, & Grandcolas, ; Vicente et al, ). Most of these recent works have focused on the tribe Lebinthini that shows the highest species diversity ( ca.…”

Crickets of the subfamily Eneopterinae (Orthoptera: Grylloidea) from Sandakan, Sabah: one new species and calling songs of a sympatric species

“…Genus Cardiodactylus Saussure, 1878 Type species: Cardiodactylus novaeguineae (Haan, 1842) Cardiodactylus borneoe Robillard & Gorochov, 2014(Figs. 11, 12) Robillard et al, 2014Dong et al, 2018: 6 (molecular phylogeny); Cigliano et al, 2019 (Orthoptera Species File). Calling song ( Fig.…”