Cytogenetic analysis of three species of Pseudacteon (Diptera, Phoridae) parasitoids of the fire ants using standard and molecular techniques

Pseudacteon flies, parasitoids of worker ants, are being intensively studied as potentially effective agents in the biological control of the invasive pest fire ant genus Solenopsis (Hymenoptera: Formicidae). This is the first attempt to describe the karyotype of P. curvatus Borgmeier, P. nocens Borgmeier and P. tricuspis Borgmeier. The three species possess 2n = 6; chromosomes I and II were metacentric in the three species, but chromosome pair III was subtelocentric in P. curvatus and P. tricuspis, and telocentric in P. nocens. All three species possess a C positive band in chromosome II, lack C positive heterochromatin on chromosome I, and are mostly differentiated with respect to chromosome III. P. curvatus and P. tricuspis possess a C positive band, but at different locations, whereas this band is absent in P. nocens. Heterochromatic bands are neither AT nor GC rich as revealed by fluorescent banding. In situ hybridization with an 18S rDNA probe revealed a signal on chromosome II in a similar location to the C positive band in the three species. The apparent lack of morphologically distinct sex chromosomes is consistent with proposals of environmental sex determination in the genus. Small differences detected in chromosome length and morphology suggests that chromosomes have been highly conserved during the evolutionary radiation of Pseudacteon. Possible mechanisms of karyotype evolution in the three species are suggested

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae)

The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini

Conserved number of U2 snDNA sites in Piabina argentea, Piabarchus stramineus and two Bryconamericus species (Characidae, Stevardiinae)

ABSTRACT The chromosomal location of 5S rRNA and U2 snRNA genes of Piabina argentea, Piabarchus stramineus and two Bryconamericus species from two different Brazilian river basins were investigated, in order to contribute to the understanding of evolutionary characteristics of these repetitive DNAs in the subfamily Stevardiinae. The diploid chromosome number was 2n = 52 for Bryconamericus cf. iheringii, Bryconamericus turiuba, Piabarchus stramineus and Piabina argentea. The 5S rDNA clusters were located on one chromosome pair in P. stramineus and B. cf. iheringii, and on two pairs in B. turiuba and P. argentea. The U2 snDNA clusters were located on the one pair in all species. Two-color FISH experiments showed that the co-localization between 5S rDNA and U2 snDNA in P. stramineus can represent a marker for this species. Thus, the present study demonstrated that the number of U2 snDNA clusters observed for the four species was conserved, but particular characteristics can be found in the genome of each species

Phylogenetic relationships of Simpsonichthys subgenera (Cyprinodontiformes, Rivulidae), including a proposal for a new genus.

The Italian endemic voles belonging to the Microtus savii group (de Sélys-Longchamps, 1838) include five controversial taxa, namely M. savii savii, M. s. niethammericus Contoli 2003 M. s. tolfetanus Contoli 2003, M. s. nebrodensis (Miná Palumbo, 1868) and M. brachycercus (Lehamann, 1961). A previous mtDNA phylogenetic analysis revealed three main mtDNA lineages that do not correspond to the recognized taxa. Here, we perform a comprehensive univariate and multivariate analysis of craniodental measurements in 151 specimens from 54 geographic samples belonging to the three main phylogroups. Qualitative data on the skull of 126 specimens were also obtained from 54 localities. Moreover, we sequenced the nuclear DNA ? fibrinogen intron 7 (?-fibint7) of 23 specimens from 12 localities and Cyt b sequences of 11 new specimens from seven localities. The pattern of morphological and cytogenomic divergence does not corroborate the current taxonomic framework and indicates that M. nebrodensis is a Sicilian endemic species

Chromosomal evolution in Gekkonidae. I. Chromosome painting between Gekko and Hemidactylus species reveals phylogenetic relationships within the group

Geckos are a large group of lizards characterized by a rich variety of species, different modes of sex determination and diverse karyotypes. In spite of many unresolved questions on lizards' phylogeny and taxonomy, the karyotypes of most geckos have been studied by conventional cytogenetic methods only. We used flow-sorted chromosome-specific painting probes of Japanese gecko (Gekko japonicus), Mediterranean house gecko (Hemidactylus turcicus) and flat-tailed house gecko (Hemidactylus platyurus) to reveal homologous regions and to study karyotype evolution in seven gecko species (Gekko gecko, G. japonicus, G. ulikovskii, G. vittatus, Hemidactylus frenatus, H. platyurus and H. turcicus). Generally, the karyotypes of geckos were found to be conserved, but we revealed some characteristic rearrangements including both fissions and fusions in Hemidactylus. The karyotype of H. platyurus contained a heteromorphic pair in all female individuals, where one of the homologues had a terminal DAPI-negative and C-positive heterochromatic block that might indicate a putative sex chromosome. Among two male individuals studied, only one carried such a polymorphism, and the second one had none, suggesting a possible ZZ/ZW sex determination in some populations of this species. We found that all Gekko species have retained the putative ancestral karyotype, whilst the fission of the largest ancestral chromosome occurred in the ancestor of modern Hemidactylus species. Three common fissions occurred in the ancestor of Mediterranean house and flat-tailed house geckos, suggesting their sister group relationships. PCR-assisted mapping on flow-sorted chromosome libraries with conserved DMRT1 gene primers in G. japonicus indicates the localization of DMRT1 gene on chromosome 6

Revisiting the systematics of the Leptodactylus melanonotus group (Anura: Leptodactylidae): redescription of L. petersii and revalidation of its junior synonyms

The Leptodactylus melanonotus species group is widely distributed across the Neotropics and contains 17 valid taxa. Here we reassess the taxonomic status of several taxa of the group, focusing mainly on the Amazonian L. petersii and both its junior synonyms (L. brevipes and L. intermedius), based on morphological, acoustic, cytogenetic, and DNA sequence data. The phylogenetic analyses recovered a monophyletic L. melanonotus group. However, L. petersii in the broad sense was found to be polyphyletic by containing the nominal species and two other lineages more closely related to L. podicipinus than to L. petersii. Color patterns and calls also support the distinctiveness among these lineages. Moreover, one of the lineages (L. brevipes) has a unique karyotype in the genus (2n = 20 vs. 2n = 22 in the other species). The holotype of L. petersii is presumably lost and a previous designation was later considered as invalid. Therefore, we designate a neotype for L. petersii and redescribe the species from the upper Negro River drainage. Also, we revalidate and characterize L. brevipes and L. intermedius from their type localities. Our study contributes to the systematics, cytogenetic and phenotypic variation, and distribution patterns of leptodactylid frogs in South America.Fil: Gazoni, Thiago. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Lyra, Mariana L.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Ron, Santiago R.. Pontificia Universidad Católica del Ecuador; EcuadorFil: Strüssmann, Christine. Universidade Federal de Mato Grosso; BrasilFil: Baldo, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Narimatsu, Hideki. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Pansonato, André. Universidade Federal de Mato Grosso; BrasilFil: Schneider, Rosio Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Giaretta, Ariovaldo A.. Universidade Federal de Uberlandia; BrasilFil: Haddad, Célio F.B.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Parise-Maltempi, Patricia P.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Carvalho, Thiago R.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasi

Idiograms with DAPI-CMA₃ bands present in the species of <i>Boana</i> and <i>Hyloscirtus</i> studied in this paper.

<p>Scale indicates percentage relative size of chromosome pairs.</p