Reliability of field determination in three cryptic whiskered bats (Myotis alcathoe, M. mystacinus, M. brandtii) and basic biometric characters: evidence from the Czech Republic
Abstract
The Alcathoe bat (Myotis alcathoe), the whiskered bat (Myotis mystacinus) and the Brandt’s bat (Myotis brandtii) represent three cryptic species living in sympatry across much of Europe. Although their determination based solely on external characters has been widely used in field research, there is no study addressing the reliability of such determination.
Based on material of bats identified with the help of genetic methods, we aimed (1) to analyse the reliability of field determination, (2) to compare basic quantitative measurements (forearm length, length of tibia, body mass) and (3) to provide information on the reliability of using these measurements for field identification of these three species based on mate- rial from the Czech Republic. Fourteen of 359 individuals (3.9%) were originally erroneously determined based on external characters.
Eight per cent of bats originally determined as M. alcathoe were in fact different species. In all M. mystacinus bats, the original species determination was confirmed using the molecular analysis (i.e. 0% determination error).
Four per cent of bats (5 inds.) originally determined as M. brandtii were assigned to M. mystacinus using molecular methods. The three species significantly differed in forearm length, the length of tibia and body mass.
Although a considerable overlap of marginal values always existed, the lowest one was recorded between M. alcathoe and M. brandtii. The best model for discrimination among the three species included sex, forearm length and body mass.
However, ca. 69–94% correctness of assignment based solely on these three variables stresses the importance of using a combination of both metric and qualitative characters (i.e. colouration, ear and dental morphology) to further improve the reliability of determination.