Itaropsis

Jaiswara, Ranjana, Balakrishnan, Rohini, Robillard, Tony, Rao, Karthik, Cruaud, Corinne & Desutter-Grandcolas, Laure, 2012, Testing concordance in species boundaries using acoustic, morphological, and molecular data in the field cricket genus Itaropsis (Orthoptera: Grylloidea, Gryllidae: Gryllinae), Zoological Journal of the Linnean Society 164 (2), pp. 285-303 : 299

ITAROPSIS TAXONOMY AND DISTRIBUTION

The three morphologically cryptic lineages of Itaropsis show exclusive distributions: one is widely distributed and extends from Bombay to Bangalore, a second is located in the Western Ghats and coastal areas of southern Karnataka, and the third has been found in Valparai, south of the Palghat Gap. Our first clade could correspond to the nominal Itaropsis parviceps , as these were collected from the type locality of the species. The type specimen is a male, and identification will have to be confirmed by specimen comparison. On the other hand, the type of I. tenella is a female: preliminary observations show that female genitalia differ geographically, but the extent and significance of this variation have to be checked on a larger scale. As a working hypothesis, and to test the synonymy proposed by Chopard (1969), we propose the existence of two distinct species in the genus Itaropsis : Itaropsis tenella from Sri Lanka and Itaropsis parviceps from western continental India, the latter subdivided into three subspecies, one in the Bombay –Bangalore area, one north of the Palghat gap in the Western Ghats of Karnataka, and one south of the Palghat Gap in the Anaimalais (Valparai).

From a biogeographical point of view, these findings are in agreement with studies on other taxa in the Western Ghats. An extensive study ( Bossuyt et al., 2004) on the historical biogeography of six taxonomic groups (tree frogs, caecilians, uropeltid snakes, freshwater fishes, crabs, and shrimps) distributed in India and Sri Lanka revealed that the Palk Strait has acted as an effective barrier to gene flow in spite of sea-level changes in geological time that should have allowed species to cross this barrier.

Further, the Palghat Gap, which is a 40-km-wide break in the almost continuous chain of the Western Ghats, has also been proposed to be a biogeographical barrier, based on studies of species distributions and genetic structure ( Ripley & Beehler, 1990). Recent studies on the population genetic structure of two large, vagile vertebrate species, the Asian elephant ( Elephas maximus ) and the white-bellied shortwing ( Brachypterys major ), a montane forest bird, have revealed large genetic differences between populations north and south of the Palghat Gap ( Vidya et al., 2005; Robin, Sinha & Ramakrishnan, 2010). In the case of the shortwing, the genetic differences are sufficiently large to warrant dividing it into two species ( Robin et al., 2010). Our finding that Itaropsis specimens south of the Palghat Gap (from Valparai) differ in song and molecular data from those north of the Palghat Gap (Kadari) is thus not surprising.

The low differentiation of Itaropsis phylogenetic lineages could indicate that this genus has differentiated only recently, as most species distributed both in the Western Ghats and in Sri Lanka. The open habitat of Itaropsis could lend support to this hypothesis: up to now, areas of endemism have always been delimited and documented for forest living species; these species inhabit the series of hills that make the Western Ghats and may have evolved in isolation during sea level rise ( Inger et al., 1987). The pattern of distribution of Itaropsis lineages show that areas of endemism could also apply to the open habitat biotas occurring in these regions ( Das et al., 2006), but perhaps that the time of biotic differentiation may be delayed.