Multiple morphological characters needed for field identification of cryptic long‐eared bat species around the Swiss Alps

Abstract

The identification of cryptic species may significantly change our view about their distribution, abundance, ecology and therefore conservation status. In the European Alps, molecular studies have revealed the existence of three sibling species of plecotine bats Plecotus auritus, Plecotus austriacus and, very recently, Plecotus macrobullaris. Knowledge of the ecological niche partitioning of cryptic species is a requisite to develop sound conservation policies. Yet, this requests the development of unambiguous identification methods easily applicable in the field. This study investigates the reliability of several morphological methods used for species recognition and proposes a new identification key for field workers. We captured 214 Plecotus bats from 29 sites in four bioregions within Switzerland, collected biopsy punches for genetic analysis, described and measured external morphological characters. All three species occurred as mono-specific colonies, except at one site where P. auritus and P. macrobullaris shared the same church attic. Qualitative traits alone did not allow a reliable separation of the three species. A series of multivariate analyses conducted on external linear measurements resulted in a discriminant function enabling correct species classification with a 97.5% probability. Compared with genetic analysis, our multivariate morphological method represents a valuable, rapid and cost-effective alternative.

Trophic niche partitioning of cryptic species of long-eared bats in Switzerland: implications for conservation

“…All sites were already known as relatively large maternal colonies (20-40 females) from a previous study (Ashrafi et al 2010). Faecal samples were obtained from bats mist-netted at the entrance of their attic roost-to minimise disturbance of the colony -when returning from their nocturnal foraging.…”

“…Faecal samples were obtained from bats mist-netted at the entrance of their attic roost-to minimise disturbance of the colony -when returning from their nocturnal foraging. For each roost, the species" identity had been previously assessed (in 2006) by DNA analysis of several individuals in each roost (Ashrafi et al 2010). During the present study, we further identified individuals based on eight external characters, as suggested by Ashrafi et al (2010).…”

“…Beside the two formerly recognized species (Plecotus auritus and P. austriacus), molecular markers could evidence the existence in the European Alps of a third cryptic species, P. macrobullaris (Kiefer and Veith 2001;Spitzenberger et al 2002Spitzenberger et al , 2003. In Switzerland, this species was mainly known in the Alpine massif, above 600 m altitude, where it can be found in sympatry with P. auritus and in the vicinity of P. austriacus (Rutishauser et al unpublished data; Ashrafi et al 2010).…”

“…The three long-eared bats of Europe are not only morphologically extremely similar but also genetically closely related (Kiefer et al 2002;Spitzenberger et al 2006): actually, there is no single external morphological character that enables full species distinction (Ashrafi et al 2010). The apparently stable co-existence of sympatric populations of P. macrobullaris and P. auritus in the Swiss Alps has to have been achieved through a process of ecological niche differentiation (Arlettaz et al 1997).…”

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“…Plecotus species are overall very similar to each other, which makes their field identification extremely complex and sometimes impossible. In particular, their biometric characteristics greatly overlap between species, and the lack of easily recognizable morphological characters (Ashrafi et al 2010, Tvrtkovic et al 2005, strongly suggests that genetic analyses need to be performed in order to correctly identify the various species, especially outside their common distribution range (Alberdi et al 2016). The identification uncertainty is the basis for the scarcity of circumstantiated records of Plecotus macrobullaris, and as a result, its conservation status is Data Deficient (DD) in the Italian Red List of Mammals (Rondinini et al 2013).…”