Speciation, karyotypic differentiation, and hybrid zones in the Leibunum curvipalpe group (Arachnida, Opiliones)

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The Leiobunum curvipalpe-group, consisting of 11 species (L.hiraiwai, L.montanum, L.kohyai, L.sadoense, L.simplum, L.hiasai, L.hikocola, L.curvipalpe, L.tohokuense, L.globosum, and L.manubriatum) shows great karyotypic variability both between and within species. Moreover, in two species of the group.occurrence of polyploid races are also known. Geographical patterns of the karyotypic differentiation and the role of the chromosomal hybrid zones in the speciation process of the group were investigated. The principal results obtained are as follows. 1.It was found that chromosomes of Leiobunum mohtanum varied from 2n=18 to 20/22 in eastern part of the Chugoku Mountains, Honshu. 2.A morphologically very divergent form of L.montanum, named Ohginosen race, was newly found around Mt Ohginosen in easternmost Tottori Prefecture. 3.Principal component analyses of 11 morphological characters for populations of L.montanum in and near Tottori Prefecture revealed occurrence of three groups that correspond well with geographical locations. 4.Samples for DNA analyses were accumulated for six of 11 species of the curvipalpe-group. A phylogenetic analysis is just getting underway. 5.A model to explain extraordinarily high emergence of gynandromorphs in a tetraploid facultative thelytoke, L.globosum.