Chromosomal diversity in three species of Lycosa Latreille, 1804 (Araneae, Lycosidae): Inferences on diversification of diploid number and sexual chromosome systems in Lycosinae.

Lycosa is one of the most speciose genera in Lycosidae, including species with different sexual chromosome systems (SCS). We carried out cytogenetic analyses in three species of Lycosa, revealing that L. erythrognatha and L. sericovittata share 2n ♂ = 22 and SCS X1X20 while L. gr. nordenskjoldi presents 2n ♂ = 19 and SCS XO, composed only of acrocentric chromosomes. All species shared pericentromeric heterochromatin. Nonetheless, one specimen of L. sericovittata carried two chromosomes with terminal heterochromatin and L. gr. nordenskjoldi showed four chromosomes with interstitial heterochromatin plus another chromosome with terminal C-bands. The pericentromeric heterochromatin of all species as well as the terminal heterochromatic blocks in L. sericovittata were CMA3+. The 18S rDNA sites varied in number and type of bearing chromosomes both at inter and intrapopulational levels, with the highest variation in L. gr. nordenskjoldi. These differences may be related to gene dispersal due to the influence of transposition elements and translocation events. Despite these variations, all species shared ribosomal sites in pair 5. This study demonstrated intra and interspecific chromosomal variability of Lycosa, suggesting that chromosomal rearrangements are related to the diversification of diploid number and SCS in this group of spiders.

Chromosome comparison among five species of Neotropical cichlids of Cichlasoma and Gymnogeophagus (Perciformes).

The genera Cichlasoma and Gymnogeophagus belong to the subfamily Cichlinae, the only one in Neotropical cichlids. Cichlasoma dimerus, C. paranaense, C. portalegrense, Gymnogeophagus rhabdotus, and G. lacustris were collected at different points in the Paranapanema and Paraguay basins and the Lagoon of Patos hydrographic system. In addition to conventional analysis, CMA3 fluorochrome staining, and FISH with 18S rDNA probe were performed. All species had a diploid number equal to 48, with interand intraspecific differences in karyotype formulae. All species presented a single AgNOR site, except G. rhabdotus and the C. paranaense population of the Paranapanema River, which revealed more than one pair of nucleolar chromosomes. AgNORs were coincident to 18S rDNA and CMA3. Heterochromatin was distributed in the pericentromeric chromosomal regions and coincident with NORs. For the first time, this work shows cytogenetic data for C. portalegrense, G. lacustris, and G. rhabdotus. Although some results reinforce the idea of conservative chromosome evolution of 2n in Cichlinae, interspecific and populational variations observed confirm that chromosomal rearrangements affect the microstructural karyotype diversification in this group of fish.

Karyotype diversity between species of Crenicichla (Perciformes, Cichlidae) from different Brazilian hydrographic basins.

Crenicichla is the largest genus in the Cichlidae family in South America. The genus includes 100 valid species that are popularly known in Brazil as jacundás or joaninhas and are widely distributed in rivers east of the Andes. Cytogenetic analyses were carried out on seven species in this genus. All species showed a diploid number of 48 with interspecific differences in karyotype formulas and AgNORs located in interstitial position on the short arm of the largest metacentric pair, except for the two populations from C. britskii. Population A showed terminal markings on the long arm of the fifth pair of the complement, and population B showed up to two marked chromosome pairs. FISH with an 18S rDNA probe was coincident with AgNORs and CMA3, except for pair 6 from population B of C. britskii that did not presented positive CMA3 sites. This work presents first cytogenetic data for C. haroldoi, C. maculata, and C. punctata, and the results show karyotypic patterns similar to those in the literature. However, the diversity found in populations of C. britskii represents new information about the evolution of the karyotype of the Cichlidae family, which has been conservative. Furthermore, the data could assist in phylogenetic studies of Crenicichla.

Repetitive DNA in the Catfish Genome: rDNA, Microsatellites, and Tc1-Mariner Transposon Sequences in Imparfinis Species (Siluriformes, Heptapteridae).

Physical mapping of repetitive DNA families in the karyotypes of fish is important to understand the organization and evolution of different orders, families, genera, or species. Fish in the genus Imparfinis show diverse karyotypes with various diploid numbers and ribosomal DNA (rDNA) locations. Here we isolated and characterized Tc1-mariner nucleotide sequences from Imparfinis schubarti, and mapped their locations together with 18S rDNA, 5S rDNA, and microsatellite probes in Imparfinis borodini and I. schubarti chromosomes. The physical mapping of Tc1/Mariner on chromosomes revealed dispersed signals in heterochromatin blocks with small accumulations in the terminal and interstitial regions of I. borodini and I. schubarti. Tc1/Mariner was coincident with rDNA chromosomes sites in both species, suggesting that this transposable element may have participated in the dispersion and evolution of these sequences in the fish genome. Our analysis suggests that different transposons and microsatellites have accumulated in the I. borodini and I. schubarti genomes and that the distribution patterns of these elements may be related to karyotype evolution within Imparfinis.

Mitotic and Meiotic Behavior of B Chromosomes in Crenicichla lepidota: New Report in the Family Cichlidae.

B chromosomes are additional genetic elements to the standard complement. They display distinctive features and have been found in 15% of eukaryote species. In this study, we analyzed 4 populations of Crenicichla lepidota from hydrographic system of Laguna dos Patos/RS (Brazil). All specimens showed 2n = 48 with 6m + 42st - a, FN = 54, with a secondary constriction on the first pair of the complement. Among the 18 samples analyzed, 6 individuals belonging to the Gasômetro and Saco da Alemoa populations presented 1-3 small-sized heterochromatic B chromosomes, with intra- and interindividual variation. Simple AgNORs coincident with 18S rDNA and CMA3 positive/DAPI negative sites were present in all populations. The extra chromosomes did not exhibit any 18S rDNA sites. The meiotic analyses showed heteropycnotic regions in leptotene and zygotene stages, which may be related to the presence of B chromosomes. During pachytene were found 24 bivalents and 1 spatially separated, as well as during metaphases I and diplotene, indicating that there is no association between B chromosomes and those of the A complement. During diakinesis, an unusual meiotic configuration was observed, revealing a proximity between the bivalent and chromosome B (univalent), that might be the result of a heterochromatin affinity between these chromosomes. In anaphase I, late migration of B chromosomes was detected. The low frequency of B chromosomes in the Cichlidae family and in Crenicichla suggests its recent origin in this group and may be ascribable to animal exposure to deleterious effects under certain environmental conditions. Moreover, this is the first report in C. lepidota.

Activity patterns of nucleolar organizer region during spermatogenesis of different curimatid species (Characiformes: Curimatidae).

The nucleolus is an important nuclear structure where transcription of ribosomal DNA (rDNA) takes place. During mitotic division, the nucleolus passes through different processes that inactivate rDNA transcription; in meiosis, its reassembly takes place during telophase II. The objective of this study was to identify the activity patterns and localization of nucleolar organizer regions (NORs) during meiotic division in fish species of the family Curimatidae. For this analysis, the meiotic division in five curimatid species was studied using silver nitrate impregnation, fluorescent in situ hybridization (FISH), and base-specific fluorochrome staining. Silver nitrate staining indicated the presence of a nucleolus in interphase nuclei, one chromosome pair in the spermatogonial metaphases, and one bivalent at the pachytene stage. No Ag-NORs were identified for cells at the diplotene, diakinesis, metaphase I, or metaphase II stages; however, FISH confirmed the presence of Ag-NORs in the nuclei, in spermatogonia, and at the pachytene phase. FISH identified this region during the other stages of meiosis, as did fluorochrome CMA3 staining, which revealed fluorescent marks corresponding to NORs during all stages of meiosis analyzed. The gene activity and localization of this ribosomal sequence during the different stages involved will also be discussed.

Sympatric occurrence of four cytotypes and one extra chromosome in Bryconamericus ecai (Characidae): 18S rDNA polymorphism and heterochromatin composition.

In the present study, specimens of Bryconamericus ecai collected from the Forquetinha River/RS, were cytogenetically analyzed, disclosing a wide karyotypic diversity in this species. All individuals had 2n = 50, with different karyotypic formulae, resulting in four cytotypes and one B macrochromosome observed in cytotype III. Heterochromatin was distributed in the pericentromeric region of most chromosomes on the four cytotypes and also on a chromosome pair with interstitial markings in cytotype IV. Staining with CMA(3) and DAPI fluorochromes revealed a C-band region rich in AT base pairs in cytotypes I, II and III, and a pair with GC-rich heterochromatin in cytotypes II and III. Cytotype IV presented CMA(3) and DAPI positive heterochromatin. Silver nitrate impregnation, in situ hybridization, and fluorochrome staining showed a multiple system of AgNORs, 18S rDNA and CMA(3) sites in cytotypes I, III and IV, with both inter-and intraindividual variability in the number and location of these sites. Cytotype II had only one pair of NORs coincident with the 18S rDNA and CMA(3) sites, indicating a simple system. The chromosomal polymorphism observed among the specimens of B. ecai added to the literature data show that chromosomal rearrangements, especially pericentric inversions, play an important role in the karyotypic evolution of this group of fish. It can also be implied that more than one species of Bryconamericus is probably occurring, living in sympatry in the Forquetinha River/RS.

Chromosome studies of Astyanax jacuhiensis Cope, 1894 (Characidae) from the Tramandai River Basin, Brazil, using in situ hybridization with the 18S rDNA probe, DAPI and CMA3 staining.

The genus Astyanax comprises 86 species of fish distributed in Brazilian river basins and is considered of the Incertae sedis group within the family Characidae. This study presents an analysis of 12 specimens of Astyanax jacuhiensis from the Tramandai River Basin, RS Brazil: 6 from the Maquiné River and 6 from the Quadros Lagoon. All specimens showed a diploid number equal to 50 chromosomes with different karyotypic formula between the two localities. The population from the Maquiné River showed 10m+26sm+6st+8a (FN=92). Fish from the Quadros Lagoon showed 12m+20sm+6st+12a (FN=88). AgNORs were evidenced in the short arm of one acrocentric chromosome pair in both populations, confirmed by FISH with the 18S rDNA probe. CMA3 fluorochrome corresponded with the AgNOR sites, while DAPI staining was negative in these regions. C banding revealed that heterochromatin was weakly distributed, mainly in the pericentromeric and terminal regions in most chromosomes. Analyses of male gonadal tissue were conducted with the objective of characterizing the meiotic chromosome behavior in A. jacuhiensis. The following stages were evidenced: spermatogonial with 50 chromosomes, pachytene and metaphase I with 25 bivalents, and metaphase II with 25 chromosomes, thus confirming the diploid number of the species. Chromosomal abnormalities were not observed. This study shows preliminary data on A. jacuhiensis from the Tramandai River Basin, contributing with more chromosomal information for this group of fish.

First chromosomal analysis in Deinopidae (Araneae) reveals Sex Chromosome System X1X2X3X4, B chromosomes and polymorphism for centric fusion.

Here we present the first cytogentic study concerning Deinopidae and their controversial phylogenetic position. This study karyologically analyzed one population of Deinopis biaculeata Simon, 1906 and five populations of Deinopis plurituberculata Mello-Leitão, 1925. The majority of specimens of D. plurituberculata exhibited 2n♂ = 40 and 2n♀ = 44 telocentric chromosomes (however some of them showed B chromosomes, belongs to Aquidauana and Botucatu population). The Deinopis biaculeata and D. plurituberculata meiosis of males showed 18 autosomal bivalents + X1X2X3X4, n = 22 and n = 18, a rare sex chromosome system (SCS) in spiders. Some individuals of D. plurituberculata from the Campo Grande population exhibited 2n♂ = 39 and 2n♀ = 43, with a metacentric chromosome (heterozygotes for centric fusion). The D. plurituberculata males with the rearrangement exhibit diplotenes with 16 autosomal bivalents + 1 autosomal trivalent + X1X2X3X4 and metaphases II with n = 22 (18 telocentric autosomes + X1X2X3X4), n = 21 (16 telocentric autosomes + a metacentric autosome + X1X2X3X4), n = 18 (18 telocentric autosomes) and n = 17 (16 telocentric autosomes + a metacentric autosome). The Ag-NORs (silver impregnation) are terminally located in a pair, coinciding with secondary constriction, which is the most common configuration for Araneae. The relatively high diploid number in Deinopis corroborates phylogenies that place it in a basal position among Entelegynes, in the UDOH grade (Uloboridae, Deinopidae, Oecobiidae and Hersiliidae). Centric fusion in only one population of D. plurituberculata suggests low dispersion capacity of this species and an absence of homozygotes for fusion suggests their low viability or a need to increase the population sampling of D. plurituberculata exhibiting the rearrangement. B chromosomes were detected in D. plurituberculata, with interpopulacional, intrapopulacional and intraindividual numerical variation, with cells presenting 0 - 3 and 0 - 6 B chromosomes in populations of Aquidauana and Botucatu, respectively.

Cytogenetic characterization of Geophagus brasiliensis and two species of Gymnogeophagus (Cichlidae: Geophaginae) from Guaiba Lake, RS, Brazil.

The karyotypes of three species of fish of the Cichlidae family from the Forqueta river and several locations in Guaiba lake/RS (Brazil) were analyzed. All species presented 2n=48, while Gymnogeophagus gymnogenys showed two karyotypic formulae: 4m+44st-a with FN=52 and 6m+42st-a with FN=54. Gymnogeophagus labiatus presented 4m+4sm+40st-a and FN=56 and Geophagus brasiliensis 4sm+44st-a and FN=52. Simple NORs were found in all species with the exception of a population of G. gymnogenys from Saco da Alemoa/Barra do Ribeiro. CMA3 staining revealed NOR sites, while DAPI staining was negative and heterochromatin was limited to pericentromeric regions an d associated to NORs, except in G. labiatus. The data show a conserved pattern in Geophagus brasiliensis and karyotype variation in the species of Gymnogeophagus.

Insights on repetitive DNA behavior in two species of Ctenus Walckenaer, 1805 and Guasuctenus Polotow and Brescovit, 2019 (Araneae, Ctenidae): Evolutionary profile of H3 histone, 18S rRNA genes and heterochromatin distribution.

Ctenidae represents one of the most representative spider families in the tropical forests of Brazil. Its largest genus, Ctenus, has approximately 220 species out of the more than 520 Ctenidae species described, and several authors consider it polyphyletic. Chromosomal data are only available for four species of Ctenus, representing a large gap in the cytogenetic knowledge about the group. This study provided cytogenetic data on two Ctenus species and one Guasuctenus (previously described as Ctenus). All showed 2n♂ = 28 (26+X1X20). Guasuctenus longipes presented two chromosome pairs containing 18S rDNA genes and C. medius, however C. ornatus showed only one chromosome pair with the 18S rDNA gene. Hybridization data using histone H3 probe indicated specific profiles: histone H3 genes were found in one chromosome pair in G. longipes, in three pairs in C. medius, and in four pairs in C. ornatus. Furthermore, supernumerary chromosomes were identified in C. ornatus presenting a meiotic behavior similar to that of sex chromosomes; and a trivalent was found in C. medius, formed by the association of one sex chromosome and an autosomal bivalent, indicating the importance of these events for the diversification of sex chromosomes in spiders. The C-banding pattern was similar between C. medius and C. ornatus with regard to the number and locations of heterochromatic bands, suggesting that heterochromatin amplification and dispersion, affect karyotypic evolution in the genus. Cytogenetic data showed similarity between C. medius and C. ornatus, and differentiation of G. longipes congruent with morphological data. Moreover, although more comparative analyses are needed to specify composition of the dispersed heterochromatin in Ctenus, the mapping of heterochromatic bands provided insights about the evolution of the karyotypes in this genus.

Karyotypes of two species of the genus Pimelodus (Siluriformes, Pimelodidae).

A cytogenetic study was conducted on two species of the genus Pimelodus that were collected from the Piquiri river, Paraná, Brazil: Pimelodus paranaensis and Pimelodus heraldoi. Both had a diploid number of 2n=56 chromosomes and a fundamental number (FN) of 104. In P. paranaensis, the karyotype consisted of 22m+22sm+4st+8a chromosomes, whereas the karyotype of P. heraldoi consisted of 18m+24sm+6st+8a. The AgNORs were localized in the terminal region of the long arm in one pair of subtelocentric chromosomes, pair 24 in P. paranaensis and pair 23 in P. heraldoi. The latter species showed size heteromorphism of these regions between the chromosome homologues. Heterochromatin was distributed mainly in the terminal regions in the two species. CMA3-positive staining was observed in some chromosomes, besides being associated with NORs, which were all DAPI-negative, in both species of Pimelodus. C-banding plus CMA3 and DAPI showed that most of the heterochromatic regions were rich in AT bases in P. paranaensis and P. heraldoi.

B chromosomes in four different populations of Rhamdia quelen (Siluriformes, Heptapteridae): a comparative study of frequency and distribution.

In the present study 25 specimens of Rhamdia quelen from four different localities were analyzed cytogenetically. All showed a diploid number of 58 chromosomes, with a karyotypic formula of 36m + 16sm + 6st and FN = 116. Metacentric B chromosomes showing inter- and intraindividual variation were observed in all populations. C-banding revealed differences in the heterochromatin distribution pattern, with evidence of completely heterochromatic B chromosomes in three populations: Agua das Pedras, Agua dos Patos and Taquari rivers, and partially heterochromatic B chromosomes in the population at the fish farm station in Timbó/SC. The occurrence of B chromosomes in such distinct populations suggests that they could have arisen from the same ancestral state, before the geographic dispersal of this species.

The Karyotypic Diversification of Calophysines and the Exallodontus-Propimelodus Clade (Pimelodidae, Siluriformes): A Cytotaxonomic and Evolutionary Approach in Pimelodidae Based on Ancestral State Reconstruction.

Pimelodidae family is one of the most diverse and widely distributed fish groups in South America. Phylogenetic analysis in the family have recently indicated the existence of two main clades: "sorubiminae" and the OCP clade, including Pimelodus ornatus, "calophysines" and "pimelodines." The aim of this study was to investigate the karyotype of three Amazonian Pimelodidae species: Calophysus macropterus, Propimelodus eigenmanni, and Exallodontus aguanai associating them to the literature, seeking to reconstruct probable ancestral characters. C. macropterus has 2n = 50, 20m+20sm+10a (fundamental number [FN] = 90), simple interstitial nucleolar organizing regions (NORs), and four 5S rDNA sites terminals, two in synteny with the 18S rDNA. P. eigenmanni has 2n = 56, 28m+20sm+2st+6a (FN = 106), simple NORs, and two 5S rDNA sites terminals. E. aguanai has 2n = 56, 36m+12sm+2st+6a (FN = 106) and 18S and 5S rDNA sites interstitial syntenic in the chromosome 1. All species exhibited a higher amount of heterochromatin, differing from the pattern of the family, and strong marking associated with NORs. The integration between molecular phylogenetic data and karyotype data indicated a high probability that 2n = 56 and simple terminals NORs in the short arm are ancestral characters in Pimelodidae, evidenced in "sorubiminae." In the OCP clade derived traits were observed resulting from chromosomal changes that played a critical role in the karyotype evolution of the group.

Genetic and Chromosomal Differentiation of Rhamdia quelen (Siluriformes, Heptapteridae) Revealed by Repetitive Molecular Markers and DNA Barcoding.

Rhamdia quelen, a species of Heptapteridae, is considered to be a complex because of taxonomic and phylogenetic inconsistencies. Determining the physical location of repetitive DNA sequences on the chromosomes and the DNA barcode might increase our understanding of these inconsistencies within different groups of fish. To this end, we analyzed R. quelen populations from two river basins in Brazil, Paraguay and Parana, using DNA barcoding and different chromosomal markers, including U2 snDNA, which has never been analyzed for any Rhamdia species. Cytochrome c oxidase I gene sequence analysis revealed a significant differentiation among populations from the Miranda and Quexada rivers, with genetic distances compatible to those found among different species in neotropical fishes. Our results, in general, revealed a conservative chromosomal evolution in R. quelen and a differential distribution of some markers, such as 5S rDNA and U2 snDNA, in different populations. We suggest that R. quelen must undergo a major revision in its morphological, genetic, and cytogenetic molecular and taxonomic structure to elucidate possible operational taxonomic units.

Analyses of the structure of NORs in two species of South American Sorubiminae fishes (Siluriformes) by means of several cytogenetic techniques.

Several cytogenetic techniques (AgNOR, C- G- and RE bandings, DAPI, CMA3 and FISH) were applied in order to analyze the structure and variability of NORs in the fish species Steindachneridion melanodermatum and S. scripta. Ag-NORs were observed on the short arm of the first acrocentric chromosome pair, coincidentally with a strong C-positive band on a large secondary constriction. In addition, NORs showed bright fluorescent signals when stained with CMA3 and treated for FISH with rDNA 18S. However, they showed negative coloration after G- and restriction enzyme banding and DAPI staining. The results evidence a substantial size polymorphism in these regions. The NOR bearing chromosomes in both species may be considered homologues because they maintain conserved characteristics, such as being interspersed with a GC-rich heterochromatin and possessing target sequences for AluI, BamHI and EcoRI.

Cytogenetic Trends in Two Families of the Neotropical Catfishes: Heptapteridae and Pseudopimelodidae (Siluriformes).

Several neotropical Siluriformes groups suffered important taxonomic revisions based on the evaluation of morphological and molecular characteristics that allow the construction of new phylogenetic hypothesis. In the present study were cytogenetically analyzed six species belonging to Heptapteridae (Cetopsorhamdia iheringi, Phenacorhamdia tenebrosa, Rhamdella eriarcha, Pimelodella meeki, Pimelodella australis, Heptapterus mustelinus) and two to Pseudopimelodidae families (Microglanis cottoides and Microglanis cibelae) by means of differential staining techniques to describe more precisely cytogenetic similarities and differences. The diploid number of R. eriarcha with 2n = 58 and M. cibelae with 2n = 56 were reported for the first time. Also, the lowest chromosome number (2n = 48) for P. tenebrosa was described. The chromosome-banding techniques for to put in evidence nucleolar organizers impregnated by silver nitrate ([AgNORs], chromomycin A3 [CMA3], and rDNA 18S) showed for all studied species conserved patterns, characteristic for each family. The rDNA 5S showed high variability among species or populations of both families, these regions could be simple or multiple, syntenic, or not with rDNA18S. The chromosome markers showed that both families are related not only from a morphologic point of view but also by their karyotypic characteristics, however, some of the present cytogenetic results evidence the importance of new morphologic, molecular, and phylogenetic studies to improve the knowledge of these fish groups.

Cytogenetic studies in the redtail catfish, Phractocephalus hemioliopterus (Bloch & Schneider, 1801) (Siluriformes, Pimelodidae) a giant fish from Amazon basin.

The objective of this study was to cytogenetically analyze Phractocephalus hemioliopterus comparing the findings with other data to infer relationships among Pimelodidae species. The results revealed a diploid number of 2n = 56 and the karyotype composed of 16 metacentric, 20 submetacentric, 6 subtelocentric and 14 acrocentric chromosomes (FN = 98). The Ag-NORs, 18S rDNA and CMA3 signals were coincident in location occupying the short arm of an acrocentric chromosome pair (23th), in a secondary constriction. The 5S rDNA genes were localized near the centromere on the short arms of one submetacentric chromosome pair. C-bands were localized predominantly in the terminal regions of chromosomes, including the AgNORs and a small metacentric pair with a conspicuous positive band on interstitial region. This chromosome pair could be considered a species-specific cytogenetic marker.

Cytogenetic analysis of five Ctenidae species (Araneae): detection of heterochromatin and 18S rDNA sites.

The present study aimed to cytogenetically analyse five Ctenidae species Ctenus ornatus (Keyserling, 1877), Ctenus medius (Keyserling, 1891), Phoneutria nigriventer (Keyserling, 1891), Viracucha andicola (Simon, 1906), and Enoploctenus cyclothorax (Philip Bertkau, 1880), from Brazil. All species presented a 2n♂ = 28 except for V. andicola, which showed 2n♂ = 29. Analysis of segregation and behavior of sex chromosomes during male meiosis showed a sex chromosome system of the type X1X20 in species with 28 chromosomes and X1X2X30 in V. andicola. C banding stained with fluorochromes CMA3 and DAPI revealed two distributions patterns of GC-rich heterochromatin: (i) in terminal regions of most chromosomes, as presented in C. medius, P. nigriventer, E. cyclothorax and V. andicola and (ii) in interstitial regions of most chromosomes, in addition to terminal regions, as observed for C. ornatus. The population of Ubatuba (São Paulo State) of this same species displayed an additional accumulation of GC-rich heterochromatin in one bivalent. Fluorescent in situ hybridization revealed that this bivalent corresponded to the NOR-bearing chromosome pair. All analyzed species have one bivalent with 18S rDNA site, except P. nigriventer, which has three bivalents with 18S rDNA site. Karyotypes of two species, C. medius and E. cyclothorax, are described for the first time. The latter species is the first karyotyped representative of the subfamily Acantheinae. Finally, 18S rDNA probe is used for the first time in Ctenidae at the present study.

Chromosomal diversity in three species of Lycosa Latreille, 1804 (Araneae, Lycosidae): inferences on diversification of diploid number and sexual chromosome systems in Lycosinae

Lycosa is one of the most speciose genera in Lycosidae, including species with different sexual chromosome systems (SCS). We carried out cytogenetic analyses in three species of Lycosa, revealing that L. erythrognatha and L. sericovittata share 2n ♂ = 22 and SCS X1X20 while L. gr. nordenskjoldi presents 2n ♂ = 19 and SCS XO, composed only of acrocentric chromosomes. All species shared pericentromeric heterochromatin. Nonetheless, one specimen of L. sericovittata carried two chromosomes with terminal heterochromatin and L. gr. nordenskjoldi showed four chromosomes with interstitial heterochromatin plus another chromosome with terminal C-bands. The pericentromeric heterochromatin of all species as well as the terminal heterochromatic blocks in L. sericovittata were CMA3+. The 18S rDNA sites varied in number and type of bearing chromosomes both at inter and intrapopulational levels, with the highest variation in L. gr. nordenskjoldi. These differences may be related to gene dispersal due to the influence of transposition elements and translocation events. Despite these variations, all species shared ribosomal sites in pair 5. This study demonstrated intra and interspecific chromosomal variability of Lycosa, suggesting that chromosomal rearrangements are related to the diversification of diploid number and SCS in this group of spiders.