Vol. 62, 2023

(update: 2023.8.11)

Chromosomal Study on Selected Small Araneomorph Spiders from Brazil, Including the First Records in Palpimanidae and Theridiosomatidae (Araneae, Araneomorphae)

Débora Duarte Dutra¹, Antônio Domingos Brescovit², and Douglas Araujo^1,*

¹Laboratório de Citotaxonomia e Evolução Cromossômica Animal, Programa de Pós-Graduação em Biologia Animal, Instituto de Biociências, Universidade Federal de Mato Grosso do Sul, Avenida Costa e Silva, s/n, Campo Grande, Mato Grosso do Sul, Brazil, Caixa Postal 549, CEP 79070-900. *Correspondence: E-mail: d.araujo@ufms.br (Araujo)
E-mail: deborad.dutra98@gmail.com (Dutra)
²Laboratório de Coleções Zoológicas, Instituto Butantan, Av. Vital Brasil, 1500, São Paulo, São Paulo, Brazil, CEP 05503- 900. E-mail: antonio.brescovit@butantan.gov.br (Brescovit)

(Received 24 November 2022 / Accepted 19 June 2023 / Published 11 August 2023)
Communicated by John Wang

Among the 50,474 spider species, only 849 have chromosomal data available in the literature. Fifty spider families remain unknown from a cytogenetic perspective. The aim of this study was to analyze chromosomally selected araneomorph spiders from Brazil, to contribute to the cytotaxonomy and chromosome evolution of this group. The karyotypes of 12 species belonging to families Corinnidae, Linyphiidae, Oonopidae, Palpimanidae, Theridiidae, Theridiosomatidae, Trachelidae, and Zodariidae were analyzed, including the first chromosomal record for the first two families. Specimens (with the abdomen content partially exposed by perforation) were subjected to colchicine, hypotonization, and fixation. In most cases, the total content of the abdomen was used to prepare slides by spreading of cell suspension and subsequent Giemsa staining. The results were as follows: Cinetomorpha simplex Simon, 1892 (Oonopidae) 2n♂ = 9, X0; Neotrops sp. and Neoxyphinus termitophilus (Oonopidae), 2n♂ = 7, X0; Otiothops birabeni (Palpimanidae); Agyneta sp. (Linyphiidae), 2n♂ = 24, X₁X₂0; Coleosoma floridanum, Thymoites sp.1 and Thymoites sp.2 (Theridiidae), 2n♂ = 22, X1X20; Naatlo sp. (Theridiosomatidae), 2n♂ = 30, X₁X₂0; Orthobula sp. (Trachelidae) 2n♂ = 21, X0; Falconina sp. (Corinnidae), 2n♂ = 28, X₁X₂0; Epicratinus sp. (Zodariidae) 2n♂ = 42, X₁X₂0. The chromosomal morphology was determined for all the samples except for Oonopidae. Most species exhibited telocentric chromosomes, with the exception of Palpimanidae and Theridiosomatidae. The main findings: 1) support an hypothesis on ancestral karyotype of Zodariidae and Oonopidae; 2) reveal a relatively high chromosome number in Palpimanidae that supports an idea on relatively high ancestral chromosome number (2n♂ = 42) of entelegyne spiders (Palpimanoidea is sister group of entelegyne spiders); 3) show that the karyotype found in Theridiosomatidae is exceptional within the Araneoidea.

Key words: Mitosis, Meiosis, Diploid number, Sex chromosome system.

Citation: Dutra DD, Brescovit AD, Araujo D. 2023. Chromosomal study on selected small araneomorph spiders from Brazil, including the first records in Palpimanidae and Theridiosomatidae (Araneae, Araneomorphae). Zool Stud 62:42. doi:10.6620/ZS.2023.62-42.