Interspecific cytogenetic relationships in three Acestrohynchus species (Acestrohynchinae, Characiformes) reveal the existence of possible cryptic species

By

Campos, Alber Sousa
Favarato, Ramon
Feldberg, Eliana

Type

Article

Date of Publication

2020

Original Publication

Comparative cytogenetics : international journal of plant & animal cytogenetics, karyosystematics and molecular systematics

Volume

14

Series / Issue

Issue: 1

Pages

27--42

Subjects

Fish , Fish cytotaxonomy , ITS , repetitive DNA

Contributed by

Pensoft Publishers

Language

English

Published by

St. Petersburg, Russia [Published] with technical support of Zoological Institute RAS [2007]-

Identifiers

DOI: https://doi.org/10.3897/CompCytogen.v14i1.33483

 

Abstract

The karyotypes and chromosomal characteristics of threeAcestrorhynchusEigenmann et Kennedy, 1903 species were examined using conventional and molecular protocols. These species had invariably a diploid chromosome number 2n = 50.Acestrorhynchus falcatus(Block, 1794) andAcestrorhynchus falcirostris(Cuvier, 1819) had the karyotype composed of 16 metacentric (m) + 28 submetacentric (sm) + 6 subtelocentric (st) chromosomes whileAcestrorhynchus microlepis(Schomburgk, 1841) had the karyotype composed of 14m+30sm+6st elements. In this species, differences of the conventional and molecular markers between the populations of Catalão Lake (AM) and of Apeu Stream (PA) were found. Thus the individuals of Pará (Apeu) were named Acestrorhynchus prope microlepis. The distribution of the constitutive heterochromatin blocks was species-specific, with C-positive bands in the centromeric and telomeric regions of a number of different chromosomes, as well as in interstitial sites and completely heterochromatic arms. The phenotypes of nucleolus organizer region (NOR) were simple, i. e. in a terminal position on theparm of pair No. 23 except inA. microlepis, in which it was located on theqarm. Fluorescencein situhybridization (FISH) revealed 18S rDNA sites on one chromosome pair in karyotype ofA. falcirostrisand A. prope microlepis (pair No. 23) and three pairs (Nos. 12, 23, 24) inA. falcatusand (Nos. 8, 23, 24) inA. microlepis; 5S rDNA sites were detected in one chromosome pair in all three species. The mapping of the telomeric sequences revealed terminal sequences in all the chromosomes, as well as the presence of interstitial telomeric sequences (ITSs) in a number of chromosome pairs. The cytogenetic data recorded in the present study indicate that A. prope microlepis may be an unnamed species.