| Abstrakt: |
Abstract: Based on study of larval spermatocytes the karyotypes of 24 species of 16 genera and 9 families of Central European Ephemeroptera have been dexctibed in addition to 8 cpesies previously mentioned in literature. Karyotypes of the families Siphlonuridae, Oligoneuriidae, Leptophlebiidae nad Potamanthidae are mentioned for the first time. The species studied represent all major recent phylogenetic lineages within the order. In general, the Ephemeroptera show karyotypes with a renge of n=4-10 chromosomes with unclear modal number and two types of sex determination (XY/XX and X/XX, males heterogametic). Anagenetic trends forming karyotypes in individual families are suggested. Plesiomorphic line (Siphlonuridae-Baetidae) is characterized mainly by still relatively high number of acrocentirc chromoseomes and XY/XX sex determination. Derived lines show various transitions to submetacentric and metacentric chromosomes, changes in chromosome numbers (Mostly reduction) and, finally, the emergence of X/XX sex determination type in the advanced Ephemeridae and Caenidae. Parsimonial hypothetical scheme of karyotype anageneis suggested here mostly corresponds to results obtained by study of external and internal morphological structures. Relations of the mayfly karyotype to that of the Odonata, a phylogenetically most allied order, are discussed. Quite different Ephemeroptera karyotype supports the idea of the Ephemeroptera and Odonata + Neoptera sister grouping of pterygote insects. |
