Abstract
This study describes the karyotypes of three species of the genus Peckoltia (Loricariidae: Ancistrini). Fishes were collected in the Jari (Peckoltia sp. 1 and Peckoltia sp. 2) and Xingu rivers (Peckoltia vittata (Steindachner, 1881)) in the Amazon rainforest. Karyotypes were 2n = 52 for Peckoltia vittata (FN=102: 16 metacentrics (m), 20 submetacentrics (sm), 14 subtelocentrics (st), 2 acrocentrics (a)) and Peckoltia sp. 2 (FN=102: 32 m + sm, 18st, 2a). Peckoltia sp. 1 (FN=102: 44 m + sm, 6st, 2a, 1B) had 2n = 53 due to a B chromosome. The species differ in chromosomal morphology. Nucleolar Organizer Regions (NOR) was identified within a distal region of the long arm of pair 9 in Peckoltia vittata, in pair 10 and in a homologue of pair 25 in Peckoltia sp. 1, as well as in pair 17 and in a homologue of pair 18 in Peckoltia sp. 2. Chromomycin A3 banding agreed with the location of the NORs. C-banding patterns revealed large non-centromeric heterochromatic blocks, probably of a common origin. Our results suggest a higher level of similarity between Peckoltia vittata and Peckoltia sp. 1.
Highlights
Loricariidae are the largest family in the order Siluriformes, encompassing more than 700 species of Neotropical fish (Armbruster, Sabaj, 2002, http://silurus.acnatsci.org/ACSI/ taxa/Genera_by_Family/Genera_Loricariidae.html, on 06 April 06, 2009)
C-banding analysis revealed an interstitial block in the short arm of pair 1 and a large block that spanned most of the short arm of pair 2, the pericentromeric region of pair 11 and most of the long arms of pairs 9, 10, 13 and 21 (Fig. 1, B)
Our study revealed that Peckoltia has a diploid number of 52, consistent with most other members of the tribe Ancistrini
Summary
Loricariidae are the largest family in the order Siluriformes, encompassing more than 700 species of Neotropical fish (Armbruster, Sabaj, 2002, http://silurus.acnatsci.org/ACSI/ taxa/Genera_by_Family/Genera_Loricariidae.html, on 06 April 06, 2009). There has been some controversy regarding the number of families in Siluriformes and the taxonomic relationships among them. Armbruster (2004) classified Loricariidae as comprising five subfamilies: Hypoptopomatinae, Loricariinae, Neoplecostominae, Upsilodine and Hypostominae, with the tribes Corymbophanini, Rhinelepini, Hypostomini, Pterygoplichthini, and Ancistrini. Later Reis et al (2006) proposed a sixth subfamily, Delturinae, to include the loricariid genera Delturus Eigenmann et Eigenmann, 1889 and Hemipsilichthys Eigenmann et Eigenmann, 1889. The CMA -stained metaphase of the same specimen (C) revealed CMA -positive signals in the end-to-end associated NOR-bearing chromosome pair (arrows). The specimen was obtained from Xingu River (D)
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