Hidden in the dung: first record of Maculantrops hirtipes () (Diptera, Sphaeroceridae) from Brazil

Abstract We recorded for the first time the lesser dung fly Maculantrops hirtipes (Macquart, 1844) from Brazil, state of Rio Grande do Sul. Twenty-five specimens were reared from the dung of Myocastor coypus (Molina, 1782), this is the first record of the feeding substrate for the genus Maculantrops and the second only for the Archiborborinae. In addition, we describe the puparium, provide an updated distribution map and additional photographs of the species.


Introduction
Lesser dung flies (Diptera, Sphaeroceridae) are a small, worldwide distributed Acalyptratae family composed of 59 genera and over 1800 species (Papp & Roháček 2021).Species of sphaerocerid feed as larvae on a wide variety of decaying organic matter including dung, rotting vegetation, and fungi.The family is easily recognized by the short, broad hind basitarsus.The Archiborborinae is an exclusively Neotropical subfamily containing 117 described species in 8 genera (Kits & Marshall 2013, Kits & Marshall 2015).Only one of these species, Antrops truncipennis (Enderlein, 1909), has had the immature stages and their biology described (Harrison 1970, Chown 1996 a, b).
The nutria Myocastor coypus (Molina, 1782) is a Neotropical semiaquatic species that has herbivorous habits, distributed from Bolivia to southern Argentina and Chile (Woods et al. 1992, Colares et al. 2010, IUCN 2016).In Brazil, the species has its native distribution restricted to the southern, from the state of Paraná to the state of Rio Grande do Sul (Moojen 1952, Cherem et al. 2004, IUCN 2016, Peixoto-Couto et al. 2022).However, there are records of the species in the states of Rio de Janeiro (Bueno 2013), Mato Grosso do Sul (Peixoto-Couto et al. 2022), and an introduction in São Paulo (De Vivo et al. 2011).Due to its high potential to colonize available habitats (Bueno 2013), it may also occur in other states.They are large rodents, ranging between 40 cm and 60 cm long, weighing between 5 and 9 kg (Waterkeyn et al. 2010).Much of its diet is composed of aquatic plants of different species, the Poaceae family being the most common (Colares et al. 2010).They live associated with bodies of water, preferably where the terrain offers ravines or walls where they dig their refuge burrows (Silva 2014).In wetlands characterized by large expanses of water, they build their refuges on vegetation with pieces of reeds and grass, which can form large platforms (Silva 2014).The presence of trails, excavations, as well as the cylindrical, elongated and green feces are indications of the presence of this rodent (Silva 2014).
The Brazilian sphaerocerid fauna is poorly studied, with only 82 species in 28 genera registered (Miranda 2023), but this number does not reflect the real diversity of the family in the country.In this paper, we present the first report of M. hirtipes in Brazil.Additionally, we describe the puparium and the substrate on which the flies developed.We also provide an updated distribution map and include additional photographs of the species.

Material and Methods
Forty-two dung samples (Figure 1C, D, E) of M. coypus were collected at the Taim Ecological Station "32°37'33.93S52°34'41.02W"state of Rio Grande do Sul, Brazil (Figure 1A, B) in August (rainy season) of 2022 and stored in 50 ml tubes and taken to the laboratory of Universidade do Vale do Rio dos Sinos.The samples were kept in the refrigerator at ±4°C for 27 days, when the first author noticed that there were flies walking inside the tubes.The flies were identified as Archiborborinae using the identification key to the genera of Sphaeroceridae of the Neotropical Region and Nearctic Mexico (Marshall & Buck 2010) and later as Maculantrops hirtipes using the work of Kits & Marshall (2013).The individuals were euthanized 24 hours after emergence, using cotton soaked with ethyl acetate, then pinned, labeled and deposited at the zoological collection of Unisinos.
The species distribution map was created with QGIS 3.18 using coordinates from the specimen labels and locality data published in Kits & Marshall (2013) and (IUCN 2016).
The Taim Ecological Station (ESEC Taim) is a federal conservation unit located in the extreme south of Brazil.Created in 1986 on the borders of the municipalities of Rio Grande and Santa Vitória do Palmar in the state of Rio Grande do Sul, ESEC Taim protects vast wetlands, lakes, fields, dunes, forests and beaches (ICMBio 2021).It is considered one of the places with the greatest ecological significance in southern Brazil, as it provides shelter, food and a breeding ground for many species (ICMBio 2021).It is a priority area with extremely high importance for the preservation of the Pampa biome (MMA 2007).
The Taim wetlands have international relevance, protect several endemic species and have been recognized since 2017 as a RAMSAR site (ICMBio 2021).The annual average minimum temperature comprises around 23 and 14 ºC in summer and winter (Wrege et al. 2012) and the annual pluviometric precipitation varies between 1440 mm and 1452 mm (Simiioni & Wollmann 2016).Relative air humidity is 80% and remains high throughout the year (Tucci et al. 1996).2-3     Description of puparium (Figure 3).Pupa length: 6.3-7.2 mm.Color yellowish to dark brown, wrinkled transversely (Figure 3A).Abdomen with creeping welts present on anteroventral margin of segments 1-8 (Figure 3A-C).Welts consisting of widely separated, rounded teeth, those on segments 2-8 additionally with 2-3 irregular rows of minute teeth posterior to the larger teeth (Figure 3B, C).Anterior spiracular processes about twice their basal width, each bearing about 12-14 irregularly arranged papillae in a fan shape (Figure 3D-G).Anal segment with reticulate wrinkling (Figure 3H), posterior spiracular processes elevated about half their basal width, spiracular plates without hairs (Figure 3I).

Discussion
Of the 45 fecal samples of M. coypus analyzed (Figure 1C), four showed hatching flies, representing a percentage of occurrence of 9%.A total of 25 adult specimens, 23 females, two males and 22 pupae of M. hirtipes were recovered from the samples.The samples with larvae of Maculantrops are easily recognized by the dung stirred up by the tube (Figure 1D) in contrast to the tubes without larvae where the dung remains whole (Figure 1E).
The Myocastor coypus (Figure 1A, B) has its diet based on aquatic plants, feeding mainly on plants from the Poaceae family (Colares et al. 2010) frequent in the diet of this rodent in the study region (Colares et al. 2010).
As the nutria, the capybara Hydrochoerus hydrochaeris (Linnaeus, 1766) has its diet based on aquatic plants, as well as the nutria of the Poaceae family is more common (Borges & Colares 2007).The capybara is the biggest rodent species of the world (Mones & Ojasti 1986) and occurs in sympatry with nutria in the study area.During the sampling fields we also collected 50 capybara dung samples.But despite going through the same storage methodology and having similarities in their diet, no flies were observed in capybara samples.The known distribution of M. hirtipes shows remarkable overlap with the native distribution of M. coypus.Therefore, the distribution of M. hirtipes may be wider, reaching Paraguay and Bolivia, and the states of Santa Catarina and Paraná in southern Brazil.This pattern of co-distribution, along with the apparent absence of M. hirtipes in dung of H. hydrochaeris, may indicate specialization on the dung of this species.Sampling and rearing from mammal dung elsewhere in the range would be needed to more thoroughly address this.

)
Borborus hirtipes Macquart, 1844: 424 Type locality: Chile.Diagnosis.Easily recognized by the numerous dark spots on the wing and pattern of bands on the legs (Fig. 2A, B) (See Kits & Marshall (2013) for a complete description).

Figure 1 .
Figure 1.A-C.Living habitat and collection site of dung of Myocastor coypus (Molina, 1782).A. Drainage canal parallel to BR-471 highway, In the left one cattle individual and a group of six capybaras; B. Group of five M. coypus grazing together with a Southern screamer Chauna torquata (Oken, 1816) large bird on the right and a Southern lapwing Vanellus chilensis (Molina, 1782) on the lower right corner; C. Dung sample of M. coypus.D-E.Tubes with samples with dung stirred and whole respectively.