André Marsola Giroti

Comparative Cytogenetics of Seven Ctenidae Species (Araneae)

The present study elevates the number of cytogenetically analyzed ctenid species and genera from two to eight and six, respectively, presenting comparisons between chromosomal data obtained and the phylogenetic hypothesis proposed in the literature. Six ctenid species presented 13 autosomal pairs, exhibiting either X1X2O (Ctenus ornatus, Ctenus sp., Parabatinga brevipes and Phoneutria nigriventer) or X1X2X3O sex chromosome systems (Nothroctenus sp. and Viracucha andicola). Asthenoctenus borellii showed 2n ♂ = 20 + X1X2O. In all species, the chromosomes were telocentric. Some cells of one C. ornatus specimen exhibited one extra chromosome that, considering the behavioral similarities between the two chromosomes, can be considered to be supernumerary, derived from or giving rise to a sex chromosome. Silver impregnation revealed nucleolar organizer regions on one autosomal pair of C. ornatus and P. nigriventer (Cteninae) and two pairs of V. andicola (Acanthocteninae). Chromosomal data suggests that the X1X2X3O system arose several times in the evolution of entelegyne spiders, and that conversion of an X1X2O system into an X1X2X3O system and vice-versa has been a relatively common event in spiders. All the chromosomal data corroborate the close relationship between Ctenus and Phoneutria, the placement of P. brevipes within Cteninae, the placement of Anahita in a separated branch within Cteninae, and the inclusion of A. borellii in a distinct group within the ctenids (Viridasiinae), all of which are as proposed by phylogenetic hypotheses available in the literature.

Cytogenetical characterization of six orb-weaver species and review of cytogenetical data for Araneidae

Abstract The family Araneidae is the third largest among spiders and the third most studied from a cytogenetical point of view. In spite of this, only 2% of all araneids have been karyotyped. The majority of araneids analyzed possess 2n  =  24 chromosomes in males; however, the study of additional species could reveal unusual karyotype characteristics. Thus, the aim of this work is to analyze chromosomally, for the first time, six species belonging to three araneid genera from Brazil. The specimens of Alpaida leucogramma (White 1841), Alpaida truncata (Keyserling 1865), Alpaida veniliae (Keyserling 1865), Parawixia kochi (Taczanowski 1873), Parawixia velutina (Taczanowski 1878) and Wagneriana sp. were collected in Parque Nacional de Ilha Grande and in the municipality of Rio Claro. The gonads were treated with colchicine and hypotonic solution before fixation with Carnoy I solution. The results were 2n♂  =  24 (11II+X1X2) in A. leucogramma and P. velutina, and 2n♂  =  22 (10II+X1X2) in A. truncata, A. veniliae, P. kochi and Wagneriana sp. When the chromosomal morphologies were established, we observed telocentric chromosomes in all specimens save one female specimen of P. velutina. The univalent sex chromosomes were easily recognized on diplotenes. The unpaired metacentric element found in one female specimen of P. velutina with 2n  =  25 probably arises by centric fusion/fission. Araneidae is a megadiverse family composed of ∼3000 species distributed mainly in the tropics; thus the analysis of more species may provide new insights about orb-weaver chromosome evolution.

Figure 26. Ariadna Tovarensis Simon, 1893 In The Taxonomy Of The American Ariadna Audouin (Araneae: Synspermiata: Segestriidae)

FIGURE 26. Ariadna tovarensis Simon, 1893. Female (Lectoparatype) from Colonia Tovar (MNHNP-AR 14389) (A‒F): habitus dorsal (A) and ventral view (B); left leg I, prolateral (C) and retrolateral view (D); Internal genitalia, lateral view (C); Anterior receptaculum, ventral view (D). Scale bar:1mm.

Revision of the spider genus Gippsicola Hogg, 1900 (Araneae: Segestriidae)

Gippsicola Hogg is one of the four genera included in the family Segestriidae. Currently this monotypic Australian genus is represented by Gippsicola raleighi Hogg, 1900, a species described based on an immature specimen from Victoria, Australia. In this work we present a taxonomic revision of this genus, with an elucidative diagnosis, redescribing G. raleighi based on detailed morphologic characters of adult male specimens. Also, we are describing three new species: Gippsicola robusta n. sp. and G. lineata n. sp., both represented by males and females, and G. minuta n. sp., only known by the male. We provide some enlightenment on the systematics of Gippsicola and putative synapomorphies for the subfamily Segestriinae.

Chromosomal analyses of Salticinae and Lyssomaninae reveal a broad occurrence of the 2n♂ = 28, X1X20 karyotype within Salticidae

Abstract Brazil possesses the richest fauna of Salticidae in the world, including 560 species; however, no representative of the Brazilian fauna has been cytogenetically analyzed up to now. It has been demonstrated that karyotype data are a useful source for discussions on the phylogeny and chromosome differentiation of some salticid lineages. In this work, the first chromosome study of salticid species from Brazil is presented, with the addition of five genera to the 38 previously investigated worldwide. The analysis of mitotic and/or meiotic cells revealed 2n♂ = 28, X1X20 in Asaracus sp., Coryphasia sp., Chira sp., Frigga quintensis (Tullgren, 1905), and Lyssomanes pauper Mello-Leitão, 1945. This karyotype constitution is the most common for Salticidae, occurring in species of distinct clades. The diploid number 2n♀ = 28 observed in Hasarius adansoni (Audouin, 1826) is unexpected, differing in one autosomal pair from the karyotype previously registered for males of the same species. The cytogenetic information reported here reinforces the wide occurence of 2n♂ = 28, X1X20 within Salticidae, including species belonging to different clades and biogeographical regions. This karyotype is a shared character of Salticidae + Philodromidae, found exclusively in these families within Dionycha, suggesting its sister relationship already proposed in the literature.

Revalidation of the spider genus Citharoceps Chamberlin, 1924 (Araneae, Segestriidae).

Abstract Citharoceps Chamberlin was diagnosed by the presence of a very distinctive stridulatory apparatus composed of two patches of ridges on the sides of the cephalic region, and a stridulatory thorn on the prolateral region of the femur I. Currently, this genus is a junior synonym of Ariadna Audouin, with the assumption that the stridulatory apparatus could constitute an exclusive feature of its unique known species, Citharoceps fidicina Chamberlin, currently senior synonym of Citharoceps californica Chamberlin & Ivie. In the present study, Citharoceps is revalidated and redescribed based on the occurrence of the stridulatory apparatus in Citharoceps fidicina and Segestria cruzana Chamberlin & Ivie, and also on the presence of distinguishable characters, such as the length of the labium-sternum junction, ventral median spine on male metatarsi I, and strong sclerotized interpulmonary fold in females, forming a conspicuous median flap. Segestria cruzana is transfered to Citharoceps, with Citharoceps californica removed from the synonym of Citharoceps fidicina, and proposed as a junior synonym of Citharoceps cruzana, due to the similarity between the additional material examined and the original description. Males of Citharoceps fidicina and Citharoceps cruzana are described for the first time.

Chromosome evolution in lycosoid spiders (Araneomorphae): a scenario based on analysis of seven species of the families Lycosidae, Senoculidae and Trechaleidae

Abstract Within the araneomorph lineage Entelegynae, the “Higher lycosoids” (“True Lycosoids” or Lycosoidea s.s.) is one of the major clades varying in its composition based on several conflicting phylogenetic hypotheses. So far, only a few species have been studied cytogenetically. In this work, the chromosomes of a senoculid spider were investigated for the first time, along with a cytogenetic analysis of six species of the families Lycosidae and Trechaleidae. Mitotic metaphase cells of the lycosid species revealed 2n♂ = 18 + X0 in Hogna sternalis (Bertkau 1880) and Lycosa nordenskjoldi Tullgren 1905, and 2n♂ = 20 + X1X20 in Lycosa erythrognatha Lucas 1836 and Lycosa sericovittata Mello-Leitão 1939. Chromosomal analysis of the trechaleid and senoculid species showed 2n♀ = 22 in Neoctenus comosus Simon 1897 (Trechaleidae), and 2n♂ = 26 + X1X20 in Syntrechalea syntrechaloides (Mello-Leitão 1941) (Trechaleidae) and Senoculus sp. (Senoculidae). This latter karyotype is a shared feature in most species of Lycosoidea group. The mitotic and/or meiotic cells of certain individuals of Trechaleidae exhibited one extra chromosome, which could constitute a B chromosome or represent intraspecific variability in the type of sex chromosome system. The results obtained here add new information to the discussion of the main mechanisms of chromosome evolution within this group.