Phylogeny of the freshwater crabs of the Western Ghats (Brachyura, Gecarcinucidae)

Abstract

The Western Ghats mountain range in India is a biodiversity hotspot for a variety of organisms including a large number of endemic freshwater crab species and genera of the family Gecarcinucidae. The phylogenetic relationships of these taxa, however, have remained poorly understood. Here, we present a phylogeny that includes 90% of peninsular Indian genera based on mitochondrial 16S rRNA and nuclear histone H3 gene sequences. The subfamily Gecarcinucinae was found to be paraphyletic with members of two other subfamilies, Liotelphusinae and Parathelphusinae, nesting within. We identify a well‐supported clade consisting of north Indian species and one clade comprising mostly south Indian species that inhabit the southern ‘sky islands’ of the Western Ghats. Relationships of early diverging genera, however, were resolved with low support. This study also includes newly sampled material from an isolated mountain plateau in the northern part of the Western Ghats, representing a new species of Gubernatoriana, which we describe here as Gubernatoriana basalticola sp. n. The new species is immediately distinguished from its congeners and the related genera Ghatiana and Inglethelphusa by its carapace and cheliped morphology, which are unique among Indian freshwater crabs. This study highlights the urgent need for continued faunistic studies to assess the true diversity of gecarcinucid crabs on the Indian subcontinent, to fully understand the basal phylogenetic relationships within the freshwater crab family Gecarcinucidae, and to evaluate the conservation threat status and biogeography of the montane freshwater crabs of the Western Ghats.

Description of a new genus and new species of freshwater crab (Brachyura: Gecarcinucidae) from the Western Ghats, Kerala, India

“…The flagellum on the exopod of the third maxilliped is also absent or vestigial in Ghatiana, Globitelphusa, Gubernatoriana, Inglethelphusa, Pilarta and Snaha (see Pati )). As in the genera Ghatiana, Gubernatoriana (except G. basalticola Klaus, Fernandez & Yeo, 2014) and Inglethelphusa, the G2 distal segment of the new genus is short (Figures 2G and 3I for Snaha). The recently described species, G. basalticola, has an elongated G2 distal segment and more wide frontal margin, indicating that the species should be placed in a new genus (Klaus et al 2014).…”

“…As in the genera Ghatiana, Gubernatoriana (except G. basalticola Klaus, Fernandez & Yeo, 2014) and Inglethelphusa, the G2 distal segment of the new genus is short (Figures 2G and 3I for Snaha). The recently described species, G. basalticola, has an elongated G2 distal segment and more wide frontal margin, indicating that the species should be placed in a new genus (Klaus et al 2014). Other than its short to vestigial G2 distal segment, Arcithelphusa also resembles Ghatiana, Gubernatoriana and Inglethelphusa in its squarish appearance of the carapace (Figure 2A The new genus is also similar to the genus Cylindrotelphusa Alcock, 1909 in some carapace morphology and male gonopod structures, notably in the highly convex carapace, narrow front, small external orbital angle, narrowly triangular male abdomen, narrowly triangular telson with concave outer margins and an acutely triangular apex, highly curved G1 terminal segment, and short G2 distal segment (Figures 2A,B,C,D,E Figures four (A,D), five (A,B,C)).…”

“…About 35 species of freshwater crabs under 13 genera were so far reported from the Western Ghats of India (Alcock 1910;Roux 1931;Bott 1970;Bahir and Yeo 2007;Sharma 2013, 2014a, b;Klaus et al 2014). In fact, the diversity of freshwater crabs is severely underestimated in the Western Ghats, a biodiversity 'hotspot' with exceptional freshwater diversity and endemism (Raghavan et al 2014).…”

“…In fact, the diversity of freshwater crabs is severely underestimated in the Western Ghats, a biodiversity 'hotspot' with exceptional freshwater diversity and endemism (Raghavan et al 2014). This fact is evident from the discovery of a new genus and five new species during the last few years Sharma 2013, 2014a;Klaus et al 2014). Many areas of the Western Ghats were not well explored for freshwater crab diversity, and this is partly due to the difficulty in accessing remote localities.…”

“…Many areas of the Western Ghats were not well explored for freshwater crab diversity, and this is partly due to the difficulty in accessing remote localities. Since small spatial scale endemism is seen in freshwater crabs (Klaus et al 2014), many remote and poorly studied localities in the Western Ghats need to be surveyed.…”