New distribution records for Sciomyzidae species ( Insecta , Diptera ) from Rio Grande do Sul , Brazil

An inventory of the species of Sciomyzidae that occur in the Coastal Plains of southern Brazil was conducted. Sampling resulted in 304 specimens, 278 of which were collected with nets and 26 with Malaise traps. A total of 11 species distributed in eight genera were collected. New distribution records for Protodictya iguassu Steyskal, 1950 and Thecomyia lateralis (Walker, 1858) are recorded from Rio Grande do Sul.

Little is known about the Neotropical Sciomyzidae, a group of flies potentially useful in the biological control of mollusks.A total of 85 species in 23 genera occur in the region (Berg and Knutson 1978;Ferrar 1987;Knutson 1987;Marinoni and Mathis 2000).Worldwide, the family includes 600 species in 50 genera (Marinoni and Knutson 1992;Vala et al. 1999;Marinoni et al. 2003).Most described species are in the Nearctic and Palearctic regions, contrasting with many groups of flies that are more diverse in the Neotropics (Marinoni and Mathis 2000).
Sciomyzids are considered to be "true malacophages" and are classified into different behavioral groups.The biology of 203 species is known, and only three are not associated with mollusks (Knutson and Vala 2011).Sciomyzids that prey on non-operculated aquatic snails are promising in the control of species that act as intermediary hosts of diseases such as fascioliasis and schistosomiasis (Berg and Knutson 1978;Barker et al. 2004).
Among sciomyzids, Pherbellia Robineau-Desvoidy, with 95 species, and Sepedon Latreille, with 80 species, are the largest genera.Both occur worldwide.In the Neotropical region, Protodictya Malloch (8 species), Sepedonea Steyskal (13 species), Sepedomerus Steyskal (3 species) and Thecomyia Perty (12 species) are the most speciose (Marinoni and Carvalho 1993;Marinoni et al. 2003;Marinoni and Mathis 2006).They include predators of aquatic mollusks and belong to the tribe Tetanocerini.The predatory species in these three genera all belong to the same behavioral group -predators of non-operculate snails at or just below the water surface, just above surface on emergent vegetation, and occasionally those exposed on moist surfaces -as defined by Knutson and Vala (2011).
There are no apomorphic characters to facilitate the identification of sciomyzid adults.These can be differentiated from other acalyptrate dipterous by the following set of morphological characters: oral vibrissae absent; postvertical setae divergent to parallel; costal vein without breaks; subcostal vein complete, free from R 1 ; vein A 1 complete; some or all tibiae with preapical dorsal seta; body length between 2 and 13 mm and coloring of the body ranging within pale yellowbrown, gray and black.However, their monophyly is grounded in two larval characters: the malacophagous behavior of the larvae and the presence of a serrate ventral arch that articulates with the lower margin of the mouth hooks (Marinoni and Mathis 2000).
This study aims to contribute to the knowledge on the family Sciomyzidae, and to foster future studies on the taxonomy, ecology and behavior of the group in the Neotropical region, as well as the use of sciomizyds for the biological control of mollusks.With that goal in mind, we set out to make an inventory of the species that occur in the Coastal Plains of the state of Rio Grande do Sul, Brazil.
The coastal plain of Rio Grande do Sul (PCRS) is formed by the strip around the coastal lagoons Lagoa dos Patos and Lagoa Mirim-Mangueira, and the northern littoral of Rio Grande do Sul.A total of 29 collecting sites in eight municipalities and 12 localities were sampled, as shown in Table 1 and Figure 1.Eleven sites were within unprotected areas and the remaining sites were within parks, reserves, or ecological stations, namely: Taim Ecological Station (Taim E. S.), Lagoa do Peixe National Park (Lagoa do Peixe N. P.), José Lutzenberger State Park (Guarita Park), and Lami Biological Reserve (ReBio Lami).
Authorization for collecting in the protected areas was issued by the organizations responsible for maintaining each area (SISBIO authorization # 30404).
The collecting sites were selected among priority sites for the conservation of invertebrates, as defined by the Ministério do Meio Ambiente (MMA 2000).
Sampling took place between October 2011 and February 2012, in the mornings from 9:00 to 10:00.For collecting, entomological nets were used to beat the vegetation in or  After sorting and preparation of the material, specimens of Sciomyzidae were identified in the laboratory with the aid of entomological keys and descriptions by Steyskal and Knutson (1975), Steyskal (1974), Freidberg et al. (1991), Marinoni and Knutson (1992), Marinoni et al. (2003), and Marinoni and Mathis (2006).
Among the species collected, seven are classified in the same behavioral group by Knutson and Vala (2011).They are: Dictyodes dictyodes, Sepedomerus bipuncticeps, Protodictya lilloana, P. guttularis, Sepedonea giovana and Sepedonea trichotypa.According to the authors, these species are "predators of nonoperculate snails at or just below the water surface, just above the surface on emergent vegetation, and occasionally those exposed on moist surfaces." Our collecting areas are typical habitats of Sciomyzidae: marshes and wet meadows (Neff and Berg 1966).These areas are not disturbed and their substrate is not very modified.Areas with altered soil are not attractive to sciomyzids (Knutson and Vala 2011).
Adult sciomyzids are not attracted by flowers, and there is little information about which kinds of vegetation they prefer (Knutson and Vala 2011).Few specimens are collected  1.
by Malaise traps (Marinoni et al. 2004;Knutson and Carvalho 1989), making net sweeping the best collecting method for these flies.Most specimens are collected while sweeping the vegetation surrounding the water bodies inhabited by mollusks.The fact that sciomyzid adults are solitary and fly short distances may explain why they usually do not show up in Malaise.Protodictya, in our samples, was represented by the greatest number of species (three).The most abundant was P. guttularis, with 179 individuals collected with nets and four with traps (n=183).One of the species collected using Malaise traps, P. iguassu, was not represented in net samples.The distribution of this species, formerly restricted to the Brazilian states of Paraná and Santa Catarina, is now extended to Rio Grande do Sul.Protodictya iguassu also occurs in Paraguay and Argentina (records for Misiones and Buenos Aires, respectively).
Protodictya is exclusively Neotropical and includes eight species (Marinoni and Knutson 1992).Abercrombie (1970) investigated the biology of P. guttularis and P. lilloana in the laboratory.According to him, "Larvae of P. guttularis are voracious feeders on aquatic snails and seem well adapted to life at the surface film with their long posterior lobes."Abercrombie (1970) collected specimens in almost all months of the year, except for November, indicating that P. guttularis is active year-round.
After Protodictya guttularis, the most abundant species was Sepedonea trichotypa.All individuals (n=71) were collected by net sweeping.Sepedonea is exclusively Neotropical, and currently includes 13 species.Abercrombie (1970) also studied the biology of the genus species.
Dictyodes, with two species distributed in the Neotropical region (Steyskal 1974), was represented in our samples by D. dictyodes, (n=5) which was captured with Malaise and net.
Sepedomerus bipuncticeps was collected in the municipality of Barra do Ribeiro, at the margins of the Guaíba Lake (n=1).This species was previously known from Panama to Argentina, including Brazil (Knutson et al. 1976).The other species of the genus are not recorded from Brazil.Sepedomerus macropus (Walker, 1849), is distributed from south of United States to Peru, while Sepedomerus caeruleus (Melander, 1920), is restricted to Caribbean islands.
Species of Pherbellia can be parasitoids or predators.The genus is distributed worldwide and the included species are classified in different behavioral groups by Knutson and Vala (2011).We collected two species, one with Malaise trap and one with a net.
In our survey, Thecomyia lateralis was present in Malaise traps set in Torres, northern littoral of Rio Grande do Sul.Most species of Thecomyia occur in Central America, and south of it up to the southern state of Santa Catarina.Thecomyia lateralis reaches the southernmost portion of Brazil, and after this work, its distribution has been extended to Rio Grande do Sul.
In the northern hemisphere the greatest diversity of Sciomyzidae is observed in temperate areas (Berg and Knutson 1978).So, in addition to these two new records for the Rio Grande do Sul, we believe that more species will be found with increased sampling effort.
In addition, these species are predators of non-operculate snails in freshwater, which is their developmental environment.Species of this group of mollusks can be vectors of diseases such as fasciolosis and schistossomiasis.A greater knowledge of the sciomyzid species and their habitats and biology is of great importance for their potential future use as controllers of vectors.

Figure 1 .
Figure 1.Map of Rio Grande do Sul with points of collection; blue circle = collection sites, red diamond = collection sites with new records.
Townes 1972;Brown 2005;Duarte et al. 2010)as used byTownes 1972)with modifications in the collecting vial (seeTownes 1972;Brown 2005;Duarte et al. 2010)were left in the field for 8 d.Collecting vials and specimens collected with nets were taken to the Laboratory of Ecology of Parasites and Vectors of the Universidade Federal de Pelotas.

Table 2 .
List of species collected with entomological net by date of collection.Where: N = Number of specimens collected; Point= collecting locality referred to in Table 1.

Table 3 .
List of species collected with Malaise trap by date of collection;