The karyotypes of pseudoscorpions of three families, Geogarypidae, Garypinidae and Olpiidae (Arachnida: Pseudoscorpiones), were studied for the first time. Three species of the genus Geogarypus from the family Geogarypidae and 10 species belonging to 8 genera from the family Olpiidae were studied. In the genus Geogarypus the diploid chromosome numbers of males range from 15 to 23. In the family Olpiidae the male chromosome numbers vary greatly, from 7 to 23. The male karyotype of single studied member of the family Garypinidae, Garypinus dimidiatus, is composed of 33 chromosomes. It is proposed that the karyotype evolution of the families Geogarypidae and Olpiidae was characterised by a substantial decrease of chromosome numbers. The diploid numbers of some olpiids are the lowest known 2n within pseudoscorpions and even one of the lowest within the class Arachnida. In spite of a considerable reduction of diploid numbers, all species studied possess a X0 sex chromosome system that is widespread and probably ancestral in pseudoscorpions. Moreover, X chromosomes retain conservative metacentric morphology in the majority of species. During the first meiotic division of males, a high number of chiasmata were observed in some species, up to five per bivalent in Indolpium sp. The transient stage between pachytene and diplotene is typically characterised by extensive decondensation of chromatin in males of geogarypids and in Calocheiridius libanoticus, and we interpret this as a diffuse stage. This is recorded in pseudoscorpions for the first time. The relationships between some species belonging to the family Olpiidae are discussed based on the data obtained.
The aim of this study was to characterize karyotypes of central European spiders of the genera Arctosa, Tricca, and Xerolycosa (Lycosidae) with respect to the diploid chromosome number, chromosome morphology, and sex chromosomes. Karyotype data are reported for eleven species, six of them for the first time. For selected species the pattern in the distributions of the constitutive heterochromatin and the nucleolar organizer regions (NORs) was determined. The silver staining technique for detecting NORs of lycosid spiders was standardized. The male karyotype consisted of 2n = 28 (Arctosa and Tricca) or 2n = 22 (Xerolycosa) acrocentric chromosomes. The sex chromosome system was X1X20 in all species. The sex chromosomes of T. lutetiana and X. nemoralis showed unusual behaviour during late diplotene, namely temporary extension due to decondensation. C-banding technique revealed a small amount of constitutive heterochromatin at the centromeric region of the chromosomes. Two pairs of autosomes bore terminal NORs. Differences in karyotypes among Arctosa species indicate that the evolution of the karyotype in this genus involved autosome translocations and size changes in the sex chromosomes. Based on published results and those recorded in this study it is suggested that the ancestral male karyotype of the superfamily Lycosoidea consisted of 28 acrocentric chromosomes. and Petr DOLEJŠ, Tereza KOŘÍNKOVÁ, Jana MUSILOVÁ, Věra OPATOVÁ, Lenka KUBCOVÁ, Jan BUCHAR, Jiří KRÁL.
Většina pavouků je samotářských a vzájemně agresivních, ale u několika tropických a subtropických druhů vícero rodů ze 7 různých čeledí existují různé formy sociálního chování a soužití, které lze klasifikovat jako periodické, nebo permanentní a teritoriální, či neteritoriální typy sociality (subsociální, koloniální až kvazisociální). and Most spiders are solitary and aggressive towards conspecifics, but in some species there are various types of social behaviour and coexistence. Twenty-one tropical and subtropical species belonging to seven different families, live in multigeneration colonies. They are usually characterized by communal brood care, female biased sex ratio and high inbreeding.
Evoluce sociálního chování může být usnadněna specifickými změnami v organizaci genomu, které snižují genetickou variabilitu jedinců v kolonii a podporují tak vzájemnou spolupráci. Jedná se zejména o haplodiploidii blanokřídlých a komplexní heterozygotnost některých všekazů. Zvláštní pozornost je věnována evoluci karyotypu sociálních pavouků. Diskutována je komplexní heterozygotnost objevená u některých ras australské maloočky Delena cancerides (Sparassidae). Srovnání stepníků rodu Stegodyphus (Eresidae) s různými úrovněmi sociálního chování ukazuje na snižování diploidního počtu u kvazisociálních zástupců a na vznik kryptických sociálních druhů. and Sociality is often accompanied by specific changes of genome organization, which could lead to the downsizing of genetic variability among sibs. In this review, we discuss the significance of haplodiploidy in Hymenoptera and complex sex-linked heterozygosity in some Isoptera for the evolution of social behaviour. Special attention is given to social spiders, where sex-linked heterozygosity arose in the huntsman spider Delena cancerides. Cytogenetic approaches have revealed cryptic speciation events in social spiders of the genus Stegodyphus, where rapid reductions of 2n seem to be linked with the evolution of sociality.