Cytogenetic Comparison of Tityus uruguayensis and a Closely Related Undescribed Species from Eastern Argentina (Buthidae: Scorpiones)

MOLA LM; OJANGUREN AFFILASTRO AA; ADILARDI RS

Foz de Iguazú

Congreso; 21st International Chromosome Conference (ICC); 2016

ICC

Tityus uruguayensis Borelli, 1901 is the only described species of the bolivianus group from lowlands of eastern South America; however, we have recently discovered another yet undescribed species from the same area ( Tityus sp. 1). T. uruguayensis is widely distributed in Uruguay and southern Brazil, while in Argentina the only known population is from an area around building ruins in El Palmar National Park (EPNP) (Entre Ríos). Tityus sp. 1 is endemic to Paraje Tres Cerros (Corrientes), an ancient isolated low altitude hilly area of subtropical eastern Argentina. We cytogenetically compared 9 males of T. uruguayensis from EPNP and 3 males of Tityus sp. 1. Giemsa staining, C-banding, and FISH with 28S rDNA and (TTAGG) n telomere probes were performed. Both species presented holokinetic chromosomes and achiasmatic male meiosis. T. uruguayensis showed a diploid chromosome number of 2n = 31 and 3 different cytotypes: 12II + VII at meiosis I (7 males), 10II + VII + IV type 1, and 10II + VII + IV type 2. All the males presented the same heptavalent. Tityus sp. 1 showed 2 cytotypes: 2n = 32, 16II at meiosis I (2 males) and 2n = 31, 14II + III (1 male). rDNA clusters were detected at 1 terminal region of 2 pairs in T. uruguayensis and in 1 pair in Tityus sp. 1. Both species showed small C-bands at the terminal regions of almost all chromosomes and conspicuous C-bands that colocalized with rDNA sites. In Tityus sp. 1, the largest chromosome of the trivalent showed 1 interstitial C-band, which could indicate that it arose by chromosome fusion. Telomeric signals were exclusively detected at the terminal regions of all chromosomes in both species. The chromosome numbers found in both species are unusually high in the genus and in the family. The presence of 2 NOR pairs in T. uruguayensis is remarkable since most of the studied Buthidae species show only 1 NOR pair, despite the variation in chromosome number.Financial support: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET PIP 00342), Universidad de Buenos Aires (UBACYT 20020130100694BA) and Agencia Nacional de Producción Científica y Tecnológica-SECyT (PICT 2010-1665).E-Mail: rsadilardi @ yahoo.com.ar