Abstract Transposable elements are abundant and dynamic part of the genome, influencing organisms in different ways through their presence or mobilization, or by acting directly on pre- and post-transcriptional regulatory regions. We compared and evaluated the presence, structure, and copy number of three hAT superfamily transposons (hobo, BuT2, and mar) in five strains of Drosophila willistoni species. These D. willistoni strains are of different geographical origins, sampled across the north-south occurrence of this species. We used sequenced clones of the hAT elements in fluorescence in-situ hybridizations in the polytene chromosomes of three strains of D. willistoni. We also analyzed the structural characteristics and number of copies of these hAT elements in the 10 currently available sequenced genomes of the willistoni group. We found that hobo, BuT2, and mar were widely distributed in D. willistoni polytene chromosomes and sequenced genomes of the willistoni group, except for mar, which is restricted to the subgroup willistoni. Furthermore, the elements hobo, BuT2, and mar have different evolutionary histories. The transposon differences among D. willistoni strains, such as variation in the number, structure, and chromosomal distribution of hAT transposons, could reflect the genomic and chromosomal plasticity of D. willistoni species in adapting to highly variable environments.

Abstract Drosophila butantan sp. nov., a species belonging to the guarani group and closely related to Drosophila nigrifemur from Bolivia, is described based on a female, and some of its offspring, collected at the forest reserve of the Instituto de Biociências da Universidade de São Paulo, Cidade Universitária "Armando de Salles Oliveira", São Paulo City, state of São Paulo, Brazil. Although externally similar, the two apparently forest-dwelling species can be told apart by having distinct oviscapt valves and spermathecal introverts and tips. Accordingly, a proposal is made to also include D. nigrifemur, a previously unassigned species, in the guarani group. The two species seem to be also related to Drosophila alexandrei and Drosophila guaraja as indicated by their external morphology, their elongate spermathecae and the not so sharply pointed oviscapt valves. The karyotypes of the new species differ from those described for D. alexandrei and D. guaraja, while those of D. nigrifemur remain still unknown. Photomicrographs of the male and female imagines, in addition to drawings and photos of their terminalia, are also included.

ABSTRACT Two new species of Drosophilidae from Uruguay are described and illustrated: Drosophila montevidensis sp. nov. (Holotype male in MZSP: Facultad de Agronomía, Universidad de la República, Montevideo city, Department of Montevideo), and Scaptomyza pipinna sp. nov. (Holotype male in MZSP: Sarandí del Consejo, near north shore of Laguna de Castillos, Department of Rocha). The former species belongs to the D. tripunctata group and is sibling to Drosophila nappae Vilela, Valente & Basso-da-Silva, 2004, differing mainly in characters of the aedeagus. The latter is closely related to Scaptomyza striaticeps Wheeler & Takada, 1966, from which it can be distinguished by color and terminalia characters. The new Drosophila species was successfully cultured in a modified banana-agar medium which is provided. Photomicrographs of mitotic and meiotic chromosomes of D. montevidensis sp. nov. are also included.

ABSTRACT In early March 2015, three males and two females of one unknown species of Drosophila were collected from a compost pile and some garbage cans in the west region of the city of São Paulo, state of São Paulo, Brazil. Morphologically it is easily identified by the presence of the following conspicuous features: a brownish dorsal stripe along pleura, an entirely iridescent silvery-whitish frons when seen directly from the front, and a row of cuneiform setae on anteroventral side of femur of foreleg; the former two traits being more evident in males. The species was easily reared in a modified banana-agar medium and two isofemale lines were established allowing to obtain mitotic cells showing a diploid chromosome number of 2n = 8. Based both on morphological and chromosomal features, in addition to the geographical distribution, we concluded that the unknown flies belong to Drosophila nasuta Lamb, 1914, a tropical species of the nasuta subgroup of the Drosophila immigrans species group. Photomicrographs of male imagines, terminalia, mitotic and meiotic metaphase plates, as well as of female mitotic metaphase, are included.

This study investigates the species richness and abundance of Drosophila Fallén, 1823 attracted to dung and carrion baited pitfall traps in natural areas with heterogeneous habitats at the Sierra de Minas, Eastern Serranías, southeastern Uruguay. Collecting was carried out on a monthly basis (May 2002 through April 2003). Drosophilids accounted for 0.84% (n = 131) and 3.61% (n = 158) of the Diptera collected from dung (n = 15,630) and carrion (n = 4,382) pitfall traps, respectively. A total of 12 species were identified, 11 of which belong to the subgenus Drosophila (the richest) and one to the subgenus Sophophora Sturtevant, 1939. Over 90% of the Drosophila specimens collected belong to five species of the subgenus Drosophila, namely D. gaucha Jaeger & Salzano, 1953, D. immigrans Sturtevant, 1921, D. mediovittata Frota-Pessoa, 1954, D. aff. nappae Vilela, Valente & Basso-da-Silva, 2004, and D. ornatifrons Duda, 1927. Drosophila cardini Sturtevant, 1916 is recorded for the first time from Uruguay. Drosophila abundance and species richness in the four habitats sampled in the Uruguayan Eastern Serranías, namely woodlands sierra, riparian forest, pine plantation and grazing grassland, were considered to be a function of habitat conservation. Diversity indices were low in all habitats. Different habitats supported particular coprophilous and necrophilous Drosophila species. The woodland sierra represents the most preserved habitat, and contributed with the highest species richness observed. Drosophila ornatifrons was the dominant species, with a restricted habitat distribution. On the other hand, grazed grassland, an environment modified by livestock management, had the lowest species richness: only a few specimens of D. repleta Wollaston, 1858. Regarding species composition, significant differences were found in some pairwise comparisons of groups of Drosophila species that included D. ornatifrons. Fly attraction to dung can be exploited as an alternative and/or complementary collecting method in ecological studies of Drosophila assemblages in natural areas.

Chromosomal polymorphism in natural populations of Drosophila willistoni from Uruguay and southern Brazil was investigated in order to understand the genetic characteristics and evolutionary potential of these almost geographically marginal populations. The level of chromosomal polymorphism in samples from Uruguay was higher than in those from the southernmost Brazilian state of Rio Grande do Sul. The increase in the polymorphism of these populations, in which the species almost reaches its southern limit, contradicts the low level of paracentric inversion polymorphism expected under the central-marginal chromosomal polymorphism cline previously reported. The high frequency of some inversions and the presence of unique inversions in samples from Uruguay indicate the uniqueness of these populations.