Currently, 60 species of harvestmen have been karyotyped and all of these are from the Nearctic and Palearctic regions. This work is the first cytogenetic report of three gonyleptid species of the suborder Laniatores: Goniosoma aff. badium, G. proximum and G. spelaeum of the Neotropical region, from the southeastern region of Brazil. Conventional Giemsa stain chromosome preparations were obtained from embryonic cells and adult male testes. Embryo mitotic plates of G. aff. badium and G. proximum indicated 88 chromosomes, and mitotic spermatogonial plates of G. spelaeum males revealed intra-and interindividual variation of chromosome number, ranging from 92-109 chromosomes. In the three analyzed species, the mitotic chromosomes were meta-or submetacentric with no obvious sex chromosomes being identified during mitosis. Prophase I spermatocytes of G. spelaeum also revealed intra-and interindividual bivalent number variation and furthermore indicated the presence of multivalence. The karyotypes of these three Goniosoma species exhibited the largest chromosome pair with a negative heteropycnosis in the distal region of the shortest arm; chromosomes of G. spelaeum submitted to silver impregnation evidenced this negative heteropycnotic region as nucleolus organizer region (NOR). These results, when compared with cytogenetic data of other Laniatores species from the Palearctic region, indicated that a new record for diploid chromosome number probably characterize the genus Goniosoma in the Neotropical region.

Among the Opiliones, species of the suborders Cyphophthalmi, Eupnoi, Dyspnoi and Laniatores have shown very diverse diploid chromosome numbers. However, only certain Eupnoi species exhibit XY⁄XX and ZZ⁄ZW sex chromosome systems. Considering the scarcity of karyotypical information and the absence of structurally identifiable sex chromosomes in the suborder Laniatores, we decided to analyse the chromosomes and bivalents of Discocyrtus pectinifemur (Gonyleptidae) to identify possible sex differences. Testicular cells examined under light microscopy showed a high diploid number, 2n = 88, meta⁄submetacentric chromosome morphology and a nucleolar organizer region on pair 35. Prophase I microspreading observed in transmission electron microscopy exhibited 44 synaptonemal complexes with similar electron density and thickness. The total and regular synapsis between the chromosomes of the bivalents was also noted in pachytene nuclei. Male mitotic and meiotic chromosomes revealed no distinct characteristic that could be related to the occurrence of heteromorphic sex chromosomes. Evolutionary trends of chromosome differentiation in the four suborders of Opiliones are discussed here.

Pholcidae (Haplogynae) encompasses 967 described species, of which only 14 have been cytogenetic analyzed. Several chromosomal features have already been described including presence of meta-and sub-metacentric chromosomes and sex determination chromosome system (SDCS) of the X, X 1 X 2 Y, and X 1 X 2 types, which contrast with the telo-and acrocentric chromosomes and SDCS of the X 1 X 2 type typical of entelegyne spiders. To obtain further cytogenetic information for the family, we examined two pholcid species, Crossopriza lyoni (Blackwall 1867) and Physocyclus globosus (Taczanowski 1874) using both conventional staining and silver staining techniques. Crossopriza lyoni exhibited 2n ϭ 23 ϭ 22 ϩ X in males and 2n ϭ 24 ϭ 22 ϩ XX in females, while P. globosus showed 2n ϭ 15 ϭ 14 ϩ X and 4n ϭ 30 ϭ 28 ϩ 2X, both in male adults, 2n ϭ 16 ϭ 14 ϩ XX in female adults and embryos, and 2n ϭ 15 ϭ 14 ϩ X in male embryos. Both species revealed predominately metacentric and submetacentric chromosomes and a SDCS of the X/XX type. The cytogenetic data obtained in this work and those already recorded for C. lyoni indicate interpopulational and intraspecific numerical chromosome variation, suggesting the presence of chromosomal races or cytotypes in this species. The intraindividual numerical chromosome variation observed in male adult specimens of P. globosus may be explained by the presence of cytoplasmatic bridges between germ cells. The use of the silver staining technique to reveal the nucleolar organizer region (NOR) showed that chromosome pairs 4 and 6 and the X chromosome in C. lyoni are telomeric NOR-bearers, and that the chromosome pair 2 in P. globosus possesses a proximal NOR in the long arm.