Myotis aurascens, Kusjakin, 1935

Dzeverin, I., 2023, Synonymisation Of Myotis Aurascens With M. Davidii (Chiroptera, Vespertilionidae) Is Premature, Zoodiversity 57 (1), pp. 19-28 : 20-21

Benda et al. (2012) base the hypothesis of conspecificity of M. aurascens

and M. davidii on (i) morphometric data ( Benda et al., 2012: 329, table 16) and scatter plots based on them ( Benda et al., 2012: 330, figs 95, 96); (ii) outlines of skulls and the elements of the dental system of the specimens of several whiskered Myotis OTUs ( Benda et al., 2012: 332, 333, figs 97, 98); (iii) the phylogeny reconstruction based on the cytochrome b sequences ( Benda et al., 2012: 335, table 17) and a tree built on the basis of these data ( Benda et al., 2012: 333, fig. 99).

Benda et al. (2012: 329, table 16) provided the morphometric data of nine specimens: four M. mystacinus s. str., four M. davidii from Iran (i. e., M. aurascens in the previous classification by Benda & Tsytsulina (2000)) and a type specimen of M. davidii from Beijing.

The scatter plots given by Benda et al. (2012: 330, figs 95, 96) show that the Iranian specimens are markedly different from M. mystacinus s. str., and that the type specimen of M. davidii is much closer to them than to M. mystacinus s. str.

At the same time, the type specimen of M. davidii in some characters falls into the area of Iranian specimens on the plot ( fig. 1 , A–D in the present paper). In other characters it does not fall into this area, but is at a place close to this area, being smaller in most characters than Iranian specimens ( fig. 1 , A, C). In some additional characters, M. davidii is intermediate between the Iranian sample and M. mystacinus s. str. sample ( fig. 1 , B, D). Since variation patterns seem to be different for different characters, skull shape can differ in the studied OTUs. These differences do not refute the conspecificity of Iranian and Chinese steppe whiskered bats (differences are expected for populations living in geographically remote and ecologically different localities), but also they cannot be evidence in support of this hypothesis.

The name-bearing type specimen of Vespertilio davidii has not been compared with the type specimens of aurascens , popovi , sogdianus , and a number of other OTUs (possibly, subspecific) of the steppe whiskered bat (while some other type specimens are shown in the plots). In addition, samples of only four specimens are insufficient when such a complex group of taxa as the M. mystacinus complex, which comprises a number of OTUs with considerable between- and within-group variation is studied.

At most we can say from the morphometric data provided by Benda et al. (2012) that the studied Iranian steppe whiskered bats are more similar to the M. davidii type specimen than to the studied M. mystacinus s. str. sample in a number of characters.

Almost the same can be said about the drawings of Myotis skulls ( Benda et al., 2012: 332, fig. 97) and teeth ( Benda et al., 2012: 333, fig. 98). Benda et al. (2012) demonstrated four skull and teeth outlines: for M. mystacinus s. str., the type specimen of M. hyrcanicus , the steppe bat from Iran ( M. davidii according to the classification of Benda et al.; M. aurascens according to the previous classification), and the type specimen of M. davidii . The sample is hardly sufficient: the skull is a diverse and variable structure, both divergent and convergent evolutionary shifts are possible in its size and shape, at least it is needed to compare the skulls of a larger number of OTUs and take into account the within-group variation, particularly geographical, in skull and teeth size and shape for each of the OTUs under analysis.

The results of Bayesian inference analysis among the haplotypes within the Myotis mystacinus morpho-group (complete cytochrome b sequences) provided by Benda et al. (2012: fig. 99) show that the three haplotypes from the specimens collected in Eastern Kazakhstan, Tıva and South Korea form a clade, separate from the other terminal taxa of Myotis aurascens sensu Benda & Tsytsulina (2000) , but only with pairwise genetic distances varying between 3.6–6.6, which is less than half the distances between Iranian M. mystacinus and Iranian Myotis aurascens sensu Benda & Tsytsulina ( Benda et al., 2012: 337, table 18). This shows that differences between the Western and the Eastern (to which the type of M. davidii is believed to belong) populations of Myotis aurascens are of at most subspecies level. Later, such a subdivision was generally confirmed and substantiated by Çoraman et al. (2020; see below for more details).

Figures

Fig. 1. Bivariate plots of the Myotis samples listed by Benda et al. (2012) to demonstrate the correspondence of Iranian steppe whiskered bats with M. mystacinus s. str. and M. davidii. LCr is the greatest length of skull; LMd is condylar length of mandible; CM3 is length of upper toothrow between C and M3 (incl.); CM is length 3 of lower toothrow between C and M3 (incl.); LaI is width of interorbital constriction; LaN is neurocranium width; CC is rostral width between canines (incl.); M3M3 is rostral width between the third upper molars (incl.). The measurements are in mm. All measurements are from Benda et al. (2012: 329, table 16). Fig. 1, A partly repeats Fig. 95 of Benda et al. (2012: 330), however Benda et al. also added the data given by DeBlase (1980) to this figure as well as to fig. 96. M. mystacinus s. str. specimens are shown in green; M. aurascens specimens from Iran attributed by Benda et al. (2012) to M. davidii are shown in yellow; type specimen of M. davidii is shown in black. See Benda et al. (2012: 329, table 16) for more details about these specimens. The figure was obtained using R software (R Core Team, 2021).