New altitudinal distribution record and updated geographic distribution of the freshwater crab Trichodactylus fluviatilis Latreille, 1828 (Crustacea, Trichodactylidae)

The freshwater crab Trichodactylus fluviatilis Latreille, 1828 is recorded here for the first time, at an altitude above 1000 m a.s.l. Sampling was performed in the Grota stream in Campos das Vertentes, Minas Gerais state, Brazil. This new record extends the known altitudinal distribution to 1115 m a.s.l., which significantly contributes to understanding the conditioning limits and factors for this species’ distribution. Moreover, the occurrence of an ectosymbiont platyhelminth of the genus Temnocephala is also reported on the crabs collected.


Introduction
Freshwater crabs are classified in Potamoidea Ortmann, 1896, which is represented in the Americas by the families Pseudothelphusidae Ortmann, 1893 and Trichodactylidae H. Milne-Edwards, 1853 (Magalhães 2003).The Trichodactylidae are composed of 15 genera (Magalhães and Türkay 1996), which together encompass about 51 species of exclusively freshwater crabs (Yeo et al. 2008); 29 species are recorded in Brazil.Members of the Trichodactylidae occur in rivers that are part of the Atlantic drainage basins from southern Mexico to Argentina, (Magalhães 2003).In Brazil, members of this family can be found in all hydrographic basins in the country (Magalhães 2003), including those basins with intermittent rivers in the northeastern semiarid region (Freita et al. 2013).
Trichodactylus fluviatilis Latreille, 1828 is distributed in the coastal basins of the Brazilian states of Pernambuco, Alagoas, Sergipe, Bahia, Minas Gerais, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul, coinciding with the original extent of the Atlantic Forest and with the limits of the Alto Paraná river basin (Magalhães 2003).This species is found on and between rocks, on muddy bottoms, and among decaying leaves of mountainous rivers, streams, and waterfalls (Mossolim and Mantellato 2008).
Trichodactylus fluviatilis is an important component of the aquatic freshwater ecosystem trophic chain by processing organic matter and preying on small invertebrates.
It is an important food resource for fish species and other animals (Magalhães 2003), and within its geographic range it serves as food for small, riverside communities of humans (Neto 2007).Despite the importance of T. fluviatilis, studies of its biology and ecology are scarce, as is occurrence and distributional data.Therefore, we report new data on this species' altitudinal range in the Rio Grande hydrographic basin and an ectosymbiotic relationship with a temnocephalian platyhelminth of the genus Temnocephala Blanchard, 1849.We also present an up-to-date geographic distribution for this species.

Methods
The We collected T. fluviatilis individuals in Grota stream, a high-altitude watercourse with an average depth of 70 cm.The collection site in the stream was approximately 2 km from the stream's headwater source and in a rem-nant strip of Atlantic Forest (Fig. 1).The altitude was recorded using a Garmin 76CSx GPS receiver.
Sampling was executed at night for 3 hours in each field trip in January 2013 and 2014, during the crescent moon phase, and establishes a capture effort based on "AquaRAP" procedure (Rapid Assessment Protocol in Aquatic Systems; Alonso and Willink 2011) using an active search, handnet, and the artisanal fishing tool known as the "parão".The "parão" is a bamboo stick with a ball of bait placed at its tip.Sampling using a "parão" was done in 2 steps: (1) a "parão" with bait (poultry viscera) was placed in possible microhabitats of T. fluviatilis occurrence, based on experience and literature information; then (2) the collector (VGL Brito) promoted water turbidity by suspending the upstream bottom sediment, forcing animals to leave their shelter.
Collected individuals were fixed with 100% ethanol and stored at low temperature (-20 °C).In laboratory, specimens were identified based on taxonomic criteria proposed by Magalhães (2003) and Melo (2003) and sexed using abdomen morphology observation (triangular for males and rounded for females), as well as gonopod presence for males or 4 pairs of pleopods for females.Carapace width (CW) of the crabs was measured using a 0.01 mm precision caliper.Each individual was further inspected for the presence of ectosymbionts.Ectosymbionts were identified as being from the genus Temnocephala Blanchard, 1849, based on the generic description used in Damborenea and Cannon (2001) and Amato et al. (2005).Individuals and eggs of Temnocephala adhered to T. fluviatilis body were photographed.
Animals and their respective ectosymbionts were stored in the Grupo de Estudos em Ecologia e Fisiologia de Animais Aquáticos invertebrate collection of the Federal University of Rio Grande do Norte (GEEFAA/UFRN) and A review of occurrences of T. fluviatilis was made using geographic coordinate data from 2 sources.The first was a specialized literature review, and the second was based on material deposited in scientific collections and museums, accessed via the Global Biodiversity Information Facility (GBIF 2013) and Species Link (http://splink.cria.org.br/).Records that showed some inconsistency in the data (e.g. a taxonomic mismatch, invalid geographic coordinates, a lack of data about the record and its respective institution) were discarded.Lastly, in the case of occurrences that lacked geographic coordinates but had otherwise satisfactory details, the geographic coordinates were estimated using Google Earth Pro ® v. 7.1.2.2041.The institutions consulted using GBIF were: the Museum of Comparative Zoology (MCZ), Harvard University; Zoologisches Museum (ZMB), Humboldt Universität; Senckenberg Museum (SMF); the National Museum of Natural History (USNM); and the Field Museum (FMNH).
All data (primary = this study and secondary = lit-erature, GBIF and SpeciesLink, accessed on 4 March 2014) were compiled and inserted in a geospatial database, carefully discriminating the source of the record.
Records that lacked altitude information had their values provided using the altitude shapefile from the Geoprocessing Laboratory of the Federal University of Rio Grande do Sul (https://www.ufrgs.br/labgeo/).In cases of incomplete locality description and/or lacking geographic coordinates, the altitudinal values were estimated based on watercourse total amplitude, extracted by us for each locality, using the altitude shapefile.Subsequently, the resulting data were imported into a geographic information system via QuantumMap v. 2.4.0 software (QGIS Development Team 2004) using the WGS84 datum.The hydrographic ecoregion delimitation proposed by Abell et al. (2008) was added to the GIS, after being obtained from the Freshwater Ecoregions of the World (http://www.feow.org),and an altitudinal gradient, gathered from the Geoprocessing Laboratory of the Federal University of Rio Grande do Sul (https://www.Diagnosis.Sub-square shape, slightly inflated, and convex carapace (Fig. 2a).Frontal, slightly inclined downwards; frontal and anterolateral border smooth (Fig. 2a).Male abdomen subtriangular, proximal border of sixth somite with width similar to telson proximal border (Fig. 2b).Straight gonopodium with a moderately accentuated median constriction; discontinuous field of spines, displayed in 2 subequal areas on lateroventral and mesodorsal surface; symmetrical border apex rounded and slightly angled (Fig. 2c, d) (Magalhães 2003).
Based on altitudinal data, T. fluviatilis showed an altitudinal distribution from sea level (0 m) to 879 m.Animals that we collected in January 2014 were the first found above 1000 m a.s.l.(Table 1, Appendix Table A1).
The consulted database from GBIF had 50 records of T. fluviatilis for Brazil.However, only 3 records had geographic coordinates.Using locality description, it was possible to estimate 14 geographic coordinates accurately (Table 1).Two registered localities from GBIF were removed from the final map, as they were placed in the Amazon, which does not corroborate the species' geographic distribution (sensu Magalhães 2003) and, possibly, are specimens that require taxonomic review.On the SpeciesLink database, no record of this species was found.Therefore, using primary and secondary data, the updated geographic distribution of this species extends from Bahia to Rio Grande do Sul states, encompassing Espírito Santo, Rio de Janeiro, Minas Gerais, São Paulo, and Santa Catarina states (Fig. 1, Table 1, S1).

Discussion
Trichodactylus fluviatilis specimens were collected in a seasonal period characterized by having the highest concentration of rain (November to January; Melo et al. 2007).In region where our study was located, precipitation oscillates between 260 mm and 280 mm (Melo et al. 2007) and water temperature between 18 °C and 20 °C (VGLBF pers.observ.).Meanwhile, in the dry season, the rain level in this region shows a precipitation rate below 5 mm (IGAM 2014).In field observations, the number of sightings increased as local precipitation increased throughout an annual cycle.During field trips in a period of lesser rain intensity (February to October), no individuals of T. fluviatilis were seen.
Most trichodactylid crabs that occur in Brazil inhabit rivers on plains that do not exceed elevations of 300 m (Magalhães 1999).However, recent surveys have updated the altitudinal limits of Trichodactylus throughout its known geographic distribution.Recently, specimens of T. fluviatilis and T. petropolitanus were found in Serra da Paranapiacaba (São Paulo state) at elevations above 500 m (Rocha and Bueno 2004).Rocha and Bueno did not specify the upper altitude limit of their records, but according to their sampling data and by estimating elevation using satellite imagery, individuals were captured at altitudes reaching approximately 500 m a.s.l.Rocha and Bueno (2011) recorded the occurrence of T. fluviatilis at about 580 m a.s.l.(estimated, using satellite imagery) in Jacupiranga State Park, southern São Paulo state.Gomides et al. (2009) recorded T. fluviatilis at 770 m a.s.l. in Santa Cândida Municipal Biological Reserve, which is located in Juiz de Fora municipality, Minas Gerais state, southeastern Brazil.
These animals have the capacity to complement their life cycle outside of the marine environment (Rocha and Bueno 2004), and it is a significant advantage to be able to inhabit continental waters, including river headwaters at high altitudes.In finding T. fluviatilis at 1115 m a.s.l., we extending the species' altitudinal range limit by over 200 m.
New occurrence and altitudinal data, such as documented here, contributes to the faunal knowledge; it can assist in studies on evolutionary, biogeographic, and aquatic resource conservation.*Doubtful records according to geographic distribution by Magalhães (2003).
erature review, made the geographic distribution maps and revised the text; VFV performed the literature review and online database review, wrote the text and revised the text; FAMF wrote and revised the text.

Figure 1 .
Figure 1.Distribution of Trichodactylus fluviatilis Latreille, 1828 in Brazil.A, B. Distribution based on literature review and GBIF data.C. Altitudinal gradient of Minas Gerais, Southeastern region, Brazil.Highlighting the Rio Grande Sub-basin.Circle = primary data occurrence, square = secondary data occurrence, star = new altitudinal record.