Paixão, Ferreira & Paixão Spatial distribution and seasonal behavior of Endecous aguassay and Eidmanacris lencionii (Orthoptera: Grylloidea: Phalangopsidae) in an artificial iron ore cave Emanuelle Arantes Paixão1,2, Rodrigo Lopes Ferreira1,3 & Crysttian Arantes Paixão4 1 Center of Studies in Subterranean Biology, Biology Department, Federal University of Lavras, 3037 University Campus, Lavras, Minas Gerais, 37200-000, Brazil 2 [email protected] 3 [email protected] (corresponding author) 4 Center of Rural Sciences, Curitibanos Campus, Federal University of Santa Catarina, 101 Rodovia Ulysses Gaboardi Km 3, Curitibanos, Santa Catarina, 89520-000, Brazil [email protected] Key Words: Endecous aguassay (Orthoptera: Grylloidea, Phalangopsidae), Eidmanacris lencionii (Orthoptera: Grylloidea, Phalangopsidae), Nova Lima, Minas Gerais, Brazil, Spatial segregation. Cricket species of the genus Endecous (Family Phalangopsidae) are widely distributed and highly abundant in Brazilian caves (Ferreira and Martins 1999), with occurrence records in many cavities (Souza-Dias et al. 2014). Souza-Dias et al. (2014) emphasized that this genus occurs in all Brazilian biomes and in subterranean environments, and among cricket genera, it is the most conspicuous and widespread. According to Ferreira (2005), species of Endecous are troglophiles, specialized to the cave environment, and Souza-Dias et al. (2014) state that these crickets inhabit the entrance and the dark zones in caves. Eidmanacris (Family Phalangopsidae) also occurs in Brazilian caves (Pinto-da-Rocha 1995), but its occurrence in caves is still poorly known (Bolfarini 2016). This genus has straminicolous and cavicolous habits, and in the later, species of this genus use natural caves for refuge (Desutter-Grandcolas 1995). According to Souza-Dias et al. (2015), species of Eidmanacris inhabit the entrance and adjacent cavities. In general, cave-inhabiting species in these two cricket genera can be classified as generalist detritivores feeding on guano and organic debris, such as leaves and rotting logs. Ferreira (2005) proposed a trophic network for Neotropical iron ore caves in which crickets in the family Phalangopsidae feed on guano. Additionally, Phalangopsidae have been directly recorded feeding on bat guano and on bat corpses or arthropods found on guano (Ferreira and Martins 1999). Souza-Dias et al. (2014) observed Endecous apterus Bolfarini & Souza-Dias, 2013 feeding on dead arthropods (Amblypygi and Trichodamon sp.) and Silva et al. (2012) found Endecous sp. feeding on a characiform carcass. These records indicate an opportunistic generalist diet. In this study, we analyzed spatial variation of two sympatric cave crickets Endecous aguassay Mews, 2008 (Figure 1A) and Eidmanacris lencionii Bolfarini, 2016 (Figure 1B) 2017 Speleobiology Notes 9: 23–33 23 Paixão, Ferreira & Paixão inhabiting an artificial iron ore cave in Brazil (Nova Lima, Minas Gerais) in the Quadrilátero Ferrífero, one of the main Brazilian ferruginous geosystems. This artificial gallery is 30 meters of horizontal projection, with an average width and height of 1.5 and 1.8 meters respectively. Due to a sinuous passage occurring just after the entrance, most of the cavity remains in permanent and total darkness. The cave contains three primary regions where the two species were found: an outer region (first 8 meters from the entrance – a disphotic area), middle region (corresponding to 15 meters of the cave passage), and an inner region (deepest portion of the cave, last 7 meters) (Figure 2). Figure 1. Cricket species in this study, A) Endecous aguassay and B) Eidmanacris lencionii, from an artificial iron ore cave in Nova Lima, Minas Gerais, Brazil. Scale bars correspond to 1 cm. Photographs by Rodrigo L. Ferreira. The data used for our analysis came from eight monitoring trips conducted every three months from February 2005 to November 2006; sampling events took place in both rainy and dry seasons of the year. During each monitoring trip, the spatial location of each individual of E. aguassay and E. lencionii was recorded on a map of the cave. Visual surveys were conducted in pairs, with one person counting and recording the positions of individuals and the other person observing previously recorded individual to ensure that a cricket was not recorded more than once. As the cave is very narrow, we had access to all microhabitats for visual surveys. We did not identify individual crickets to life stage or gender. During each monitoring trip, the temperature and the humidity were measured on the wall in the middle part of the gallery with a Hygrotherm Center 130 hygrometer. Differences in temperature and humidity between the rainy and dry seasons were analyzed using Student's t-test and an α=0.05. Spatial point pattern analysis (SPPA; Bailey and Gatrell 1995; Gatrell et al. 1996; Diggle 2013) was employed to analyze the spatial patterns of the two species and their relationships. The intensity estimates, i.e., the expected number of points per area unit, were performed by Isotropic Gaussian Kernel (Gatrell et al. 1996; Baddeley 2010). These estimates result in intensity maps that can be used to identify possible spatial distribution patterns independent (completely random), regular or clustered for each species in each monitoring period. Furthermore, these data can be used to identify the locations in the cave where individuals tend to cluster. These spatial observations were statistically 2017 Speleobiology Notes 9: 23–33 24 Paixão, Ferreira & Paixão confirmed by K function (Ripley 1977), with simulation envelopes by the Monte Carlo method with 50,000 simulations (Gatrell et al. 1996; Baddeley 2010). Ripley (1981) stated the significance level of 5,000 simulations is about 0.0004. The cross K function was used to evaluate the spatial relationship independence, repulsion or attraction between the two species also with simulation envelopes by the Monte Carlo method with 50,000 simulations (Gatrell et al. 1996; Baddeley 2010). All analyses were performed in R software (R Core Team 2016) using the Spatstat package (Baddeley and Turner 2005). Since both species of crickets were using both the cave floor and walls, the figure representing the map of the cave was "adapted" to exhibit the current position of each individual observed. Hence, the final map is a bi-dimensional scheme of the current three- dimensional cave. For that purpose, the cave walls were "planned," thus their height was summed to the width of the cave conduit, producing the final figure. Since no cricket was observed in the cave ceiling, it was not represented in the final map. Accordingly, the cavity map used to illustrate the clustered regions for each species has 30 meters of horizontal projection and 5.1 meters of length (1.5 meters of the average width) added to the two walls (1.8 meters high of each wall) (Figure 2). Figure 2. Layout of the artificial iron ore cave located in Nova Lima city, Minas Gerais state, Brazil, in Quadrilátero Ferrífero karst area. For data analysis, the cavity was divided into three regions: Outer (first 8 meters from the entrance), Middle (corresponding to 15 meters of the cave passage), and Inner (deepest portion of the cave, last 7 meters). The average temperature recorded was 19.8°C (ranging from 18 to 21°C, SD=1.1) and the relative humidity was 87.5% (ranging from 76 to 95%, SD=7.0). The rainy and dry seasons did not differ statistically in relation to any temperature (average temperature of the rainy season was 20.4°C and the dry 19.2°C; t-stat=-1.79; d.f.=5.60; P=0.13) nor humidity (average humidity of the rainy season was 92% and the dry 83%; t-stat=2.35; d.f.=3.67; P=0.08). These results confirm the topoclimatic stability of the cavity. We observed seasonal changes in spatial distribution of both cricket species within the cave passage, varying from rainy to dry season and differing between species (Table 2017 Speleobiology Notes 9: 23–33 25 Paixão, Ferreira & Paixão 1, Figure 3). In monitoring conducted on 14 May 2005, the intensity maps of the E. aguassay (Figure 4A) and E. lencionii (Figure 4C) showed regions with a higher average density of points, i.e., clusters. The K function estimations confirm the clustered pattern for all analyzed distances between points (r) for E. lencionii (Figure 4D). However, for E. aguassay, two patterns were observed, random and clustered (Figure 4B). In most of the monitoring trips, the two species exhibited a clustered pattern at all r values except for E. aguassay on 27 February 2005 and 14 May 2005 (Figure 5A) and E. lencionii on 27 February 2005 (Figure 5B). Regarding the interaction between the two species, the intensity maps revealed a seasonal pattern (Figure 3). In the rainy season, there is a tendency of a marked segregation between the two species, with populations of E. aguassay concentrated in the middle and innermost regions of the cave, while E. lencionii tends to inhabit areas near the cave entrance. During the dry season, E. lencionii tends to concentrate in the innermost region of the cavity. However, when the estimates of the K cross function are analyzed, the spatial pattern is not so evident (Figure 5C). For example, in the second monitoring trip, the two species showed independence and attraction patterns (Figure 4E and 5C). The observed spatial patterns (Table 1, Figures 3, 4 and 5) of E. aguassay and E. lencionii may be due to several factors, including but not limited to ecological interactions, differing microhabitat preferences, degree of cave adaptation, behavioral differences, or competition but it in fact there are distinct seasonal variations that differ between the two taxa. As caves are oligotrophic environments (Culver 1982; Simon et al. 2007), the quantity and distribution of resources may be factors that contribute to the existence of the clustering pattern observed in both cricket species. Moreover, clustering may be a behavior against dehydration (Yoder et al.