Cytogenetics of Three Brazilian Goniosoma Species: A New Record for Diploid Number in Laniatores (Opiliones, Gonyleptidae, Goniosomatinae)

Abstract

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.

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

“…2002). The high diploid number herein recorded in D. pectinifemur was also reported in four laniatorean species previously analysed by Cokendolpher and Jones (1991) and Oliveira et al. (2006).…”

“…The NOR distribution pattern observed in D. pectinifemur differed from that detected in the other species of Gonyleptidae whose chromosomes were analysed (Oliveira et al. 2006).…”

“…2 n = 78 in Vonones sayi (Cosmetidae), 2 n = 88 in Goniosoma aff. badium and Goniosoma proximum , and 2 n = 92–109 in Goniosoma spelaeum (Gonyleptidae) (Cokendolpher and Jones 1991; Oliveira et al. 2006).…”

Chromosomal characteristics of a Brazilian whip spider (Amblypygi) and evolutionary relationships with other arachnid orders

“…The number and location of NORs were only established, for example, in approximately 30 species of Araneae (Král et al, 2006;Král, 2007;Oliveira et al, 2007;Rodríguez-Gil et al, 2007;Araujo et al, 2008;Stávale et al, 2010Stávale et al, , 2011Dolejš et al, 2011;Král et al, 2011), 17 species of Scorpiones (Schneider et al, 2009a,b;Schneider and Cella, 2010), 3 species of Opiliones (Gorlov and Tsurusaki, 2000;Oliveira et al, 2006;Schneider et al, 2008;Mattos et al, 2013), and two species of Palpigradi (Král et al, 2008). In almost all these species, the NORs were only identified through the use of silver impregnation; however, in an overview of the NOR distribution in Coleoptera, Schneider et al (2007) showed that the results were usually coincident when the chromosomes were examined with both silver impregnation and FISH technique.…”

Karyotype Evolution in Harvestmen of the Suborder Cyphophthalmi (Opiliones)

“…In harvestmen, the number and the distribution of rDNA loci have up to now only been examined by means of silver staining of nucleolar argyrophilic proteins, hence detecting only transcriptionally active rDNA clusters [Gorlov and Tsurusaki, 2000b;Oliveira et al, 2006;Schneider et al, 2008]. Only a single rDNA cluster was visualized in a diploid set of Psathyropus tenuipes (L. Koch, 1878) (Sclerosomatidae) [Gorlov and Tsurusaki, 2000b] and Dyscocyrtus pectinifemur (Mello-Leitão, 1937) (Gonyleptidae) [Schneider et al, 2008], while 1 pair of rDNA loci was noted in Goniosoma spelaeum (Mello-Leitão, 1932) [Oliveira et al, 2006]. In other arachnid orders, the data on the number and the position of rDNA are still fragmentary, too.…”