Opiliofauna (Arachnida, Opiliones) of the Seasonal Semidecidual Forest of the State of Minas Gerais, Brazil

There are few studies of opiliones (Arachnida) catalogs in many ecosystems and Brazilian states. In this regard, the aim of this study was to catalog the harvestmen fauna in a Seasonal Semidecidual Forest in the south of Minas Gerais. The study was conducted in 14 municipalities in the south of the State of Minas Gerais in fragments of a Seasonal Semidecidual Forest from March/2017 to April/2019. 34 morphospecies were registered, including four unknown morphospecies to science, Tricommatinae sp.1, Anoplogynus sp.1 and sp.2, and Liogonyleptoides sp.w1. Similarities in the Opiliones fauna are low within the comparative studies, which reflect on the high rates of endemism, as has been discussed in other studies. The area is relevant to the Opiliones fauna in the state of Minas Gerais, which justifies the creation of conservation units in order to ensure the protection of this natural heritage.


Introduction
Due to forest fires, logging, other human activities (LAURANCE;COCHRANE, 2001;ALENCAR et al., 2004;LAURANCE, 2004), increasing agricultural expansion has altered the tropical ecosystems (LAMBIN et al., 2003), causing not only the loss and fragmentation of the forest but also the modification in structure and quality of the habitat, which justifies the study of catalogs and species distribution in tropical rainforests, especially taxons with ecological relevance, but which are still less studied when compared to other groups (MATHIEU et al., 2005;REGO et al., 2007) such as the Opiliones order.
In the ecosystem, Opiliones play an important role in the process of organic matter decay, since they speed up the cycling of nutrients (MOORE et al., 1991). In addition, with their high rate of endemism, they are an excellent taxon for biogeographic and ecological studies (PINTO-DA-ROCHA et al., 2005;DASILVA et al., 2015).
The greatest abundance of Opiliones in the world can be found Brazil, with 1,008 described species (KURY, 2002 onwards), of which about 600 are unique to the Atlantic Rainforest, the most sampled biome for harvestmen in Brazil (BRAGAGNOLO; PINTO-DA-ROCHA, 2009), and where the greatest diversity of these arachnids are found (PINTO-DA-ROCHA, 1999;BRAGAGNOLO et al., 2007;NOGUEIRA et al., 2019a). Their sensitivity to changes in habitat, and their vulnerability to water loss (SANTOS, 2007) can explain the greater diversity in the rainforest and their nocturnal behavior (PINTO-DA-ROCHA et al., 2005).
The Atlantic Rainforest comprises a group of forest formations and associated ecosystems that include Dense Ombrophilous Forests, Mixed Ombrophilous Forests, Open Ombrophilous Forests, Seasonal Semidecidual Forests, Seasonal Decidual Forests, Sandbanks, Mangroves, and Highland Fields (OLIVEIRA-FILHO, 2006).
There are few cataloging and distribution works on opiliofauna in the state of Minas Gerais (SOARES, 1970;SOARES;SOARES, 1970;ÁZARA et al., 2016;FERREIRA et al., 2019). The first work was carried out at the Parque Nacional do Itatiaia (Itatiaia National Park), which holds rupestrian and altitude field formations, as well as Ombrophilous forests, spanning both the states of Minas Gerais and Rio de Janeiro. The second was carried out in the municipality of Poços de Caldas, in the area of a Seasonal Semidecidual Forest; the third work registered harvestmen species associated to 111 artificial hollowed underground areas in 13 municipalities, Therefore, different ecosystems and regions of the state, including those of the Atlantic Forest domain are subsampled for the opiliofauna, such as the areas of the Seasonal Semidecidual Montane Forest in the south of the state. In relation to the latter, the aim of this study was to carry out a survey on Opiliones fauna in the Seasonal Semidecidual Forest of the south of Minas Gerais.

Material and Methods
The study was conducted in 14 municipalities in the south of the state of Minas Gerais (Table 1; Figure 1), in a region where the Seasonal Semidecidual Montane Forest vegetation is predominant, as well as the phytophysiognomy of Atlantic Rainforest dominance (OLIVEIRA-FILHO, 2006). Sample collections were carried out from March/2017 to April/2019. The sampled were centered in the municipalities of Bueno Brandão, Inconfidentes and Ouro Fino due to the convenience in logistics.
The sampling method used was the active search, which consisted in walking along pre-existing paths in different forest fragments without transects demarcation or specific areas. Search prioritized the surveying of microhabitats such as leaf litter ("serapilheira"), gullies, decaying tree trunks, tree barks, under rocks and bromeliads, with the effort of three researchers per sampling.
Opiliones were captured manually with the help of forceps and placed in jars containing alcohol. In order to identify the specimens, the specialist Doc. Ricardo Pinto da Rocha (Zoology Museum of Universidade de São Paulo -USP) was consulted. The specimens were deposited in the Arachnids and Myriapods Collection of the Arachnology Laboratory at the UFRJ National Museum and in the Collection of the Zoology Laboratory of the Instituto Federal de Educação,
The following formula was used to calculate the constancy: C = (p x 100)/N, where p = number of sample collections containing the studied species and N = total number of sample collections carried out. The species were then grouped, according to Silveira Neto et al. (1976) in the categories: "constant", for the species present in more than 50% of the sample collections; "accessory", for those between 25 and 50%; and "accidental" for those present in less than 25% of the sample collections.
Species estimators (Jackknife 1) were used to evaluate the efficiency of the sample collection, with the use of Software R (R DEVELOPMENT CORE TEAM, 2017), with 1,000 repeated samplings.
In order to evaluate the similarity of the Opiliones fauna sampled in this study, works carried out in the states of São Paulo (RESENDE et al., 2012) and of Rio de Janeiro (BRAGAGNOLO; PINTO-DA-ROCHA, 2003), with a phytophysiognomy of Atlantic Rainforest dominance biome, and of the state of Minas Gerais (SOARES, 1970;ÁZARA et al., 2016;FERREIRA et al., 2019) were used. Only the material identified up to species were used in the analyses, for all the comparative studies and this one. The morphospecies identified up to genera, subfamilies, and families were not considered. A binary matrix was used to analyze the grouping with data from the presence-absence of species in each region. Using the similarity matrix obtained by the community of the Jaccard coefficient (SJ), a dendrogram was built with the UPGMA grouping method. All data was processed in software PAST 2.1 (HAMMER et al., 2001) and FITOPAC 2.1 (SHEPHERD, 2010).

Results
1,198 individuals belonging to 34 morphospecies distributed in 14 genera, nine subfamilies, three families and two suborders were sampled ( Table 2).
The most abundant species was Mischonyx cuspidatus with 669 registered individuals, followed by Discocyrtanus pertenuis with 180 and by Liogonyleptoides sp.1 with 74 specimens.
It is important to note that the taxons that are not identified to the specific level of revised Gonyleptidae subfamilies comprise females, which are morphologically homegeneous and, in general, do not present diagnostic features for specific identification.
Four morphospecies that comprise non-described species to science were sampled ( Figure 2): Anoplogynus sp.1 and sp.2 (Municipality: Albertina), Liogonyleptoides sp.1 (Inconfidentes) and Tricommatinae sp.1 (Bueno Brandão). The species estimator Jackknife 1 showed that the Opiliones fauna in the studied region can reach up to 42 species (Figure 3). A grouping of this study survey is observed in a survey by Ferreira et al. (2019). However, the latter have low faunal similarity (less than 0.5), which also occurred in the other analyzed studies (Table 3).

Discussion
The abundance of Opiliones in this study was superior to that of other surveys carried out in a Seasonal Semidecidual Forest in Minas Gerais (SOARES, 1970), in São Paulo (PINTO-DA-ROCHA et al., 2005;RESENDE et al., 2012), in Paraná and in Santa Catarina (PINTO-DA-ROCHA et al., 2005). This may be due to the fact that a larger area was sampled and to a greater sampling effort. The high abundance in Atlantic Rainforest areas is a reflection of different factors, as discussed by Nogueira et al. (2019b), who reports the occurrence of 508 species in 63 locales along the Brazilian coast in 11 states and three regions.
Contrary to most other tropical harvestmen species, which are endemic to certain geographical regions (PINTO-DA-ROCHA et al., 2005), Mischonyx cuspidatus has the largest dispersion territory among Brazilian species (KURY, 2003), besides being easily found in urban areas (MESTRE; PINTO-DA-ROCHA, 2004), demonstrating that it is a generalist species, i.e., has little specificity and a great capacity of dispersion.
The species estimator reports a high efficiency in sample collection, around 81%. However, a larger number of sample collections would allow the cataloging of more species.
The similarity of the present survey is indicated to be greater (0.21052) to the Ferreira et al. (2019) survey than others. Nevertheless, this value is low -values are only considered meaningful over 0.5 (KENT;COKER, 1992). This situation was observed in all the other studies (Table 3), which might be due to the endemism of the order, as discussed by other authors (PINTO-DA-ROCHA et al., 2005;FERREIRA et al., 2019). This justifies more catalog studies for this taxon in conservation units in those areas considered as  (DRUMMOND et al., 2005), in order to know the species and biodiversity distribution better.

The abundance of the species Mischonyx cuspidatus
and Discocyrtanus pertenuis can be explained by two factors. First, for being considered a synanthropic species of wide geographic distribution, tolerating environments impacted by human activity (BRAGAGNOLO et al., 2007;ÁZARA et al., 2018), as is characteristic of many areas sampled in this study.
The second factor is their gregarious behavior, observed, so far, in Eupnoi and Laniatores (MACHADO; MACÍAS-ORDÓÑEZ, 2007). This enabled the capture of a larger number of individuals of the species during the sampling, which impacted the registered abundance. Among the hypotheses that have been proposed for the gregarious formation in some species in this order are the protection against predators, hydro regulation, and the increase in successful mating (MACHADO; MACÍAS-ORDÓÑEZ, 2007). The gregarious individuals usually rest in moist places, under tree trunks, caves, or plants (CURTIS; MACÍAS-ORDÓÑEZ, 2007;CHELINI et al., 2011) and there is evidence of philopatry in several species: at night, the gregarious individuals go out to forage and return to their resting place at dawn (GNASPINI, 1996;MACHADO et al., 2000;GNASPINI, 2004;. It should be pointed out that the distribution of the Mischonyx species is restricted to the center/south of Brazil and spans the states of Goiás (Distrito Federal), Minas Gerais, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina and Rio Grande do Sul. Most species allocated in the genus Mischonyx have high endemism and wide allopatry (VASCONCELOS, 2003). On the other hand, Discocyrtanus pertenuis presents distribution throughout the Central region (Brazilian savanna) and east (Atlantic Rainforest in Minas Gerais and São Paulo) of Brazil (KURY; CARVALHO, 2016). Therefore, the eudominance of these species in this study and their endemic nature in the phytophysiognomy collection is justified.
The places where the new species were registered (Municipality: Bueno Brandão, Albertina, and Inconfidentes) are not found in conservation units or protected areas, which poses a threat to the maintenance of the species unknown until now, i.e., Tricommatinae sp.1 , Anoplogynus sp.1, sp.2 and Liogonyleptoides sp.1. Therefore, this research recommends carrying out long-term studies on the biology and distribution of the species, in order to identify its vulnerability.
The diverstity of opiliones may vary due to different factors, such as precipitation, temperature, altitude, and humidity, but also due to biogeographic aspects (ALMEIDA-NETO et al., 2006;NOGUEIRA et al., 2019b;FERREIRA et al., 2020), which added to the endemism rates (PINTO- DA-ROCHA et al., 2005) must be considered in order to define the conservation strategies of these animals.
Considering the results presented, the studied area is relevant to the Opiliones fauna in the state of Minas Gerais, which added to the diversity studies of other taxons in the region (PASSARI et al., 2017;AMORIM, et al., 2018;BUENO et al., 2019;VIEIRA et al., 2020), justifies the creation of Conservation Units in order to ensure the protection of this natural heritage, since none of the studied areas are included in environmental protection areas.