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Recently, we have reported the peculiar topographic separation of shortwave- and middlewave-sensitive (S and M) cones in the retina of the common house mouse (Mus musculus) and in a number of inbred laboratory mouse strains derived from the same species. In an attempt to follow the phylogeny of the complementary cone fields, we have investigated the retina of other mouse-like rodents. Two monoclonal anti-visual pigment antibodies, OS-2 and COS-1, specific to the S and M cones, respectively, have been used to identify the two cone types. Immunocytochemistry on retinal sections and on whole-mount preparations have shown that, as in the house mouse, the two cone types in the mound builder mouse (Mus spicileugus) occupy opposite halves of the retina. In contrast, in the wood mouse (Apodemus sylvaticus), both cone types are scattered uniformly across the whole retinal surface. Another distinguishing feature between the two genera is the frequency of the S cones. Whereas their density in the Mus species is above 7 000/mm2 in the S-field, the maximum density of the S cones in A. sylvaticus is one order of magnitude smaller. In another species of this genus (the herb field mouse, A. microps), the S cones are completely missing.

A new species of the genus Rhinolophus is described from Cameron Highlands, Peninsular Malaysia. The diagnostic characters are the shape of the noseleaf and external and cranial measurements. The new taxon belongs to the pusillus-group and based on the morphology of the posterior noseleaf, its closest relative is R. subbadius.