The unusual recombination potential and its ecological implications in Coenagrion m. mercuriale (Charp.) from Liechtenstein (Zygoptera: Coenagrionidae)

In the Alps, this atlanto-mediterranean species approaches the eastern limits of its European (closed up) range, appears highly specialized as to the habitats, and the number of its populations is generally declining (cf. e.g. H. SCH1ESS & J. DEMARMELS, 1979, Jber. naturf. Ges. Graubünden 98: 67-91). We were eager, therefore, to examine its karyotype, which has so far been unknown. Our friend, Rector Josef Biedermann (Planken, Liechtenstein), recently discovered a large and stable population in the Nature Reserve "Schwabbrünnen Äscher” in Liechtenstein, where we were able to collect a good series on June 16, 1988. (cf. J. BIEDERMANN, 1987, Ber. bot.-zoo!. Ges. Liechlenslein-Sargans-Werdenberg 16: 39-56). Four dissected specimens yielded some 20 micrographs of various spermatocyte stages, showing a very unusual karyotype; n $ = 13 (Fig. I). Save for a significantly larger bivalent, apparently originating from a fusion of 2 pairs of the primary complement, the elements/bivalents are graded in size, there are no m-chromosomes, and the medium-sized X is the smallest of the primary spermatocyte metaphase set.