Evaluation of a facial feature to distinguish two sympatric Water Shrew species
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Naturmuseum St.Gallen, Rorschacher Strasse 263, 9016 St. Gallen, Switzerland
SWILD - Urban Ecology & Wildlife Research, Sandstrasse 2, 8003 Zurich, Switzerland
Online publication date: 2023-12-04
Publication date: 2023-12-04
Corresponding author
Madeleine Geiger   

Naturmuseum St.Gallen
Hystrix It. J. Mamm. 2023;34(2):133-136
Species identification of the two sympatric Central European Water Shrews Neomys fodiens and N. milleri based on external features is tricky due to a relatively high variability of the traditionally used features (e.g., hair fringe on the hind feet and the tail), which in addition are often not readily visible on camera trap footage. For the Italian populations of these two species, it has relatively recently been suggested that the shape of the facial line of demarcation (line between the dark fur on the dorsal side and the lighter fur on the ventral side) can be used as an additional feature for species identification. In the current study, we evaluated this feature also in populations North of the Alps, focusing on Switzerland and – on a smaller scale – other parts of Europe. The examined, in part genetically identified specimens confirm that the facial line of demarcation shows a characteristic and mostly well discernible dichotomy between N. fodiens and N. milleri: in most of the examined N. milleri the dark facial mask involves the corners of the mouth and/or other parts of the mouth. In N. fodiens, however, there is usually an evenly spaced and relatively broad line of light fur between the mouth and the line of demarcation. This study corroborates that the shape of the facial line of demarcation is a helpful tool for the identification of these two Neomys-species and that this feature can be particularly relevant for studies using non-invasive monitoring methods such as camera traps.
We thank (sequence according to collection short names [see main text] in alphabetical order) Stefan Liersch (BNM), Manuel Ruedi (MHN), Anne-Claire Fabre and Manuel Schweizer (NMBE), Thomas Briner (ZMK), and Robert Asher and Mathew Lowe (UMZC) for access to collections and for locating specimens and specimen information, as well as Adrian Dietrich for access to his Neomys specimen and photographs. Concerning the museum specimens housed at the NMSG, we thank Sonja Bächi, Nicolas Cerf, Steven Diethelm, Elisabeth Flury, Albert Good, René Güttinger, Urs Locher, Dennis Lorenz, Katrin Szacsvay, Petra Wiesenhütter, and Rico Winkler (surnames in alphabetical order) for collecting cadavers of Neomys and donating them to the NMSG. Further, we thank Jürg Paul Müller for the inspiration to conduct this study, Manuel Ruedi for discussion, Rene Güttinger (RGBlick) for a Photograph of a N. fodiens, Marilena Palmisano and Manuel Ruedi for support with the DNA sequencing, two anonymous reviewers for helpful comments to improve the manuscript, and Lucas A. Wauters (Editor-In-Chief) and an anonymous associate editor for editorial work.
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