Species-Pairs among Insects


ATTENTION has recently been directed to the water beetles Deronectes depressus F. and D. elegans Panz. by F. Balfour-Browne in an interesting contribution to the Scottish Naturalist (Nov.-Dec. 1930, pp. 172–188). In a previous study (Ann. Mag. Nat. Hist., Ser. 9, vol. 3, pp. 293–308 ; 1919) he showed that these two species could be separated by a number of characters—size, shape, colour, tarsal claws, width of ædeagus—but that intermediates could be found which formed an unbroken series connecting the two by insensible gradations. His recent paper discusses the distribution, which is of great interest. In southern England, D. elegans only occurs; in northern England and southern Scotland, both species are found, with all grades of intermediates; in northern Scotland and throughout Ireland, only D. depressus and intermediates approximating to the D. depressus type occur.

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OMER-COOPER, J. Species-Pairs among Insects. Nature 127, 237 (1931). https://doi.org/10.1038/127237a0

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