A karyotype study on the pseudoscorpion families Geogarypidae, Garypinidae and Olpiidae (Arachnida: Pseudoscorpiones)

Abstract

Abstract. 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.

Morphological and cytogenetic characteristics of Neobisium (Blothrus) slovacum Gulička, 1977 (Pseudoscorpiones, Neobisiidae), the northernmost troglobitic species of the subgenus Blothrus in Europe

“…However, the morphology of the X chromosome is usually metacentric in this order (Šťáhlavský et al 2012a, 2013, Kotrbová et al 2016), whereas an acrocentric X was identified in N.slovacum . This morphology of the X chromosome was previously documented in only one population of Olpiumpallipes (Lucas, 1846) (Olpiidae) within pseudoscorpions (Šťáhlavský et al 2006). It was supposed to be an effect of pericentric inversion from Greece in the population concerned.…”

Conventional and ultrastructural analyses of the chromosomes ofDiscocyrtus pectinifemur(Opiliones, Laniatores, Gonyleptidae)

“…The wide diversity of chromosome numbers found in Opiliones also occurs in two related orders, Pseudoscorpiones and Scorpiones (Shanahan 1989;Sˇa´hlavsky´et al 2006). These orders, together with Solifugae, form the clade (Pseudoscorpiones + Solifugae) Scorpiones, that constitutes the sistergroup of Opiliones (Shultz 1990;Wheeler and Hayashi 1998;Giribet et al 2002).…”

Insights into the Karyotype Evolution of Charinidae, the Early-Diverging Clade of Whip Spiders (Arachnida: Amblypygi)

“…As stated above, amblypygids exhibit a considerable karyotype differentiation. Besides amblypygids, a high diversity of karyotypes has also been found in other arachnid orders, namely in spiders (2n = 5-152; [48][49][50]), scorpions (2n = 5-186; [51,52]), harvestmen (2n = 10-109; [53,54]), and pseudoscorpions (2n = 7-143; [55,56]). Compared to other arachnids, the amblypygid radiation, which took place before the collapse of Pangea and Gondwana, led to the occurrence of amblypygids in almost all continents [22]-a condition also notable in charinids [19][20][21].…”