Chromosomal Data Of Two Pholcids (Araneae, Haplogynae): A New Diploid Number And The First Cytogenetical Record For The New World Clade

• Published in: The Journal of arachnology 2005-08, Vol.33 (2), p.591-596
• Main Authors: de Araujo, D, Brescovit, AD, Rheims, CA, Cella, D M
• Format: Article
• Language: English
• Subjects: Araneae; Haplogynae; Mesabolivar luteus; Micropholcus fauroti; Pholcidae
• ISSN: 0161-8202
• DOI: 10.1043/0161-8202(2005)033[0591:CDOTPA]2.0.CO;2

Mesabolivar luteus (Keyserling 1891) and Micropholcus fauroti (Simon 1887) specimens were collected in Ubatuba and Rio Claro, both in the state of Sao Paulo, Brazil. Mesabolivar luteus showed 2n ([male ]) = 15 = 14 + X and 2n ([female]) = 16 = 14 + XX in mitotic metaphases and 7II + X in diplotenic cells. During late prophase I, all bivalents presented a ring shape, evidencing two chiasmata per bivalent. In this species, some diplotenic cells appear in pairs, maybe due to specific characteristics of the intercellular bridges. The metaphases II showed n = 7 or n = 8 = 7 + X chromosomes. Micropholcus fauroti evidenced 2n ([male ]) = 17 = 16 + X in spermatogonial metaphases and 8II+X in diplotenic cells, with only one chiasma per bivalent, contrasting with M. luteus. In both species, all chromosomes were metacentrics. The sexual chromosome X was the largest element and appeared as a univalent during meiosis I. These are the first cytogenetical data for the genera Mesabolivar and Micropholcus. Additionally, M. luteus is the first chromosomally analyzed species of the New World clade and the observed diploid number for M. fauroti had not yet been recorded in Pholcidae.