Unveiled chromosomal diversity in the Araneidae (Araneomorphae): the highest diploid number among entelegynes and the first record of the X1X2X3X4 Sex Chromosome System in the family

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Bonfim Souza, Lucas Henrique ; Costa, Caroline Correia ; Silva, Bruno Cansancao ; Dutra, Debora Duarte ; Montanholi, Arthur dos Santos ; Oliveira, Beatriz ; Roghanian, Susan ; Lemos, Larissa Candido ; Covali Pontes, Henrique Ranieri ; de Padua, Aline Agatha ; Sobrinho dos Santos Dias, Rebeca Rocha ; Brescovit, Antonio Domingos ; Araujo, Douglas

• Document type: Journal article
• Source: JOURNAL OF ARACHNOLOGY; v. 50, n. 1, p. 10-pg., 2022-05-01.

Abstract

The Araneidae is among the most speciose spider families, but there are few karyotype studies (1.9%) and some species-rich clades are without any chromosomal study. Understanding the evolution of chromosome number and Sex Chromosome Systems is made more difficult by many uncertain evolutionary relationships within the family. In this work, the chromosomal analysis of eight araneid species (Acacesia benigna Glueck, 1994, Actinosoma pentacanthum (Walckenaer, 1841), Alpaida bicornuta (Taczanowski, 1878), Dubiepeira Levi, 1991 sp., Gasteracantha cancriformis (Linnaeus, 1758), Parawixia bistriata (Rengger, 1836), Verrucosa meridionalis (Keyserling, 1892) and Verrucosa scapofracta Lise, Kesster & Silva, 2015), contribute to discussions of some evolutionary scenarios of chromosome evolution. The gonads were submitted to colchicine treatment, hypotonization, slide preparation, and Giemsa staining. The species analyzed showed 2n male = 24 (11II + X1X2), except Dubiepeira sp. with 2n male = 41 (19II + X1X2X3), and both Verrucosa species, which presented 2n male = 47 (22II + X1X2X3) in V. meridionalis and 2n male = 50 (23II + X1X2X3X4) in V. scapofracta. The species analyzed possess all chromosomes with acrojtelocentric chromosomal morphology. The 2n male = 24, X1X2 found in most species studied here is the most frequent karyotype in the Araneidae. This study presents the first chromosomal data for the diverse Glade "Micrathenines", the highest diploid number among entelegynes (2n male = 50), and the first record of an X1X2X3X4 in the Araneidae. The chromosome data suggest a series of fission events in the origin of Verrucosa karyotypes, and a close relationship between Dubiepeira sp. and Araneus ventricosus (L. Koch, 1878). Moreover, Alpaida bicornuta can be cytotaxonomically distinguished of other Alpaida species karyotyped up to now. (AU)

• FAPESP's process: 99/05446-8 - Biodiversity of Arachnida and Myriapoda of the State of São Paulo
• Grantee: Antonio Domingos Brescovit
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants