Amphibia-Reptilia 33 (2012): 337-347 Habitat use, reproductive traits and social interactions in a stream-dweller treefrog endemic to the Brazilian Cerrado Renato C. Nali1,∗, Cynthia P.A. Prado2 Abstract. The richest anuran fauna is found in the Neotropics, but the natural history of most species is unknown. Bokermannohyla ibitiguara is a stream-dweller treefrog endemic to the Brazilian Cerrado and classified as “Data Deficient” by the IUCN. Herein we describe the species’ reproductive biology. Fieldwork was conducted from August 2010 to July 2011. Reproductive activity occurred from October to June and was positively correlated with air temperature, humidity, and monthly rainfall. Individuals were observed only in gallery forests at the margins of streams and males used various kinds of substrates as calling sites. Males did not aggregate in specific parts of the streams and spatial distance between males was higher in the dry season. Males and females did not differ in length, but females without mature oocytes were lighter than males. The reproductive investment (gonad mass/body mass) of males was 0.29% and that of females was 20.26%. Female ovaries contained a mean of 202 ± 75 mature oocytes with a mean diameter of 1.96 ± 0.16 mm. We describe, for the first time for the genus, a complex courtship behaviour and also male-male fight and satellite behaviour. The Cerrado is probably the most threatened savanna in the world, having been intensively modified over the last decades. Endemic species associated to gallery forests, such as B. ibitiguara, are highly vulnerable to habitat alterations. Thus, our study provides important data on the species’ biology, which might be useful for conservation practices, but also to investigate taxonomic and phylogenetic relationships in this genus. Keywords: Bokermannohyla ibitiguara, calling sites, courtship behaviour, Hylidae, temporal distribution. Introduction urgent, in order to support conservation prac- tices. Currently, 5966 amphibian anurans are known The natural history of species is important in the world (Frost, 2011), with the highest di- not only for conservation purposes but also versity found in the American tropics (Duell- in phylogenetic and evolutionary contexts. For man, 1988). The greatest anuran richness, 946 instance, studies on anuran social interactions species, is found in Brazil (Segalla et al., 2012), may help understand sexual selection mecha- with approximately 60% of endemism (Vascon- nisms (e.g. Wells, 1977a, 1977b; Montanarin, celos and Rossa-Feres, 2005). Despite the great Kaefer and Lima, 2011). Social interactions in diversity in the Neotropics, approximately 35% anurans include courtship behaviours of vary- of the amphibians are endangered due to habi- ing complexity, involving acoustic and tactile tat loss or fragmentation, as well as a result communication (e.g. Zina and Haddad, 2007), of habitat split (Becker et al., 2007; Loyola et and aggressive behaviour, with vocal duels and al., 2008), and its huge fauna is still poorly physical combats between males (e.g. Mar- known (Haddad and Prado, 2005; Toledo and tins, Pombal-Jr and Haddad, 1998). Although Batista, 2012). This combination of facts makes our knowledge of anuran social systems has the study of species’ natural history and ecology greatly improved over the last decades (e.g. Wells, 1977a; Kirkpatrick and Ryan, 1991; 1 - Programa de Pós-graduação em Ciências Biológicas Ryan, 1997; Ursprung et al., 2011), our under- (Zoologia), Universidade Estadual Paulista, 13506-900 standing is limited by the lack of detailed stud- Rio Claro, São Paulo, Brazil ies on tropical species, which account for much 2 - Departamento de Morfologia e Fisiologia Animal, FCAV, Universidade Estadual Paulista, 14884-900 of the morphological, taxonomic, behavioural, Jaboticabal, São Paulo, Brazil and ecological diversity in this group (Zamudio ∗Corresponding author; e-mail: [email protected] and Chan, 2008). © Koninklijke Brill NV, Leiden, 2012. DOI:10.1163/15685381-00002836 338 R.C. Nali, C.P.A. Prado The genus Bokermannohyla (Faivovich et ened hotspots on Earth (Myers et al., 2000). The topogra- al., 2005), within the family Hylidae, includes phy is mountainous, with flat or rounded hills, reaching up to 1500 m in elevation, with deep valleys and many streams 29 species, distributed in central, south and (Dietz, 1984). The region was originally covered by the Cer- southestern Brazil (Frost, 2011). Together with rado vegetation, grassland fields at higher elevations, gallery the genera Hyloscirtus, Miersiohyla, Hypsiboas forests in the valleys along streams, and patches of semide- ciduous forest (Dietz, 1984). Currently, much of the region and Aplastodiscus they form the Cophoman- has been modified into pastures. The climate is markedly tini tribe, a well-supported clade (Faivovich et seasonal, with a hot and rainy summer (October to March) and a dry winter (April to September), with total annual al., 2005; D’Heursel and Haddad, 2007). Bok- precipitation between 1300-1700 mm (Queirolo and Motta- ermannohyla ibitiguara (Cardoso, 1983) is a Junior, 2007). stream-dweller treefrog, endemic to the Cerrado Fieldwork was conducted at private farms in the munic- ipality of Sacramento (19°51S; 47°26W), Minas Gerais in Southeastern Brazil. The species is currently state, Southeastern Brazil. Three streams were sampled: placed in the B. pseudopseudis group, with B. (i) permanent stream 1 (20°1621.9S; 47°0424.5W; alvarengai, B. pseudopseudis, B. saxicola, B. 677 m elevation); (ii) temporary stream (20°13 09.9 S; 47°0621W; 880 m elevation), and (iii) permanent stream oxente, and B. itapoty (Faivovich et al., 2005; 2 (20°1220.1S; 47°0753.6W, 839 m elevation). Frost, 2011). General information on its natural history can be found in the original description Data collection (Cardoso, 1983). It is a medium-size species, Seventeen field expeditions yielded 190 hours of observa- the male advertisement call is composed of pri- tions throughout a whole year (August 2010 to July 2011). Two field expeditions per month were made in the rainy mary and secondary notes, and adults inhabit season, except for March (n = 11 expeditions; 160 hours) rocky environments along small streams (Car- and one per month in the dry season (n = 6 expeditions; doso, 1983). Population status is unknown and 30 hours), lasting about 5 hours per night. For permanent streams 1 and 2, we sampled about 50 m in extension, with reproductive behaviour had never been studied a total of 80 and 75 hours of observations, respectively. For in detail, reasons used to include B. ibitiguara in the temporary stream, we sampled about 30 m, with a total of 35 hours of observations. the Data Deficient category by the IUCN (Cara- Individuals were found by active search at breeding sites maschi and Eterovick, 2004). guided by male vocalizations and were observed with flash- Herein, we describe the reproductive biology lights. To reduce the interference of luminosity on the frogs’ behaviour, red lights were used (e.g. Miranda et al., 2008), of B. ibitiguara, including habitat use patterns, avoiding, whenever possible, to point the light focus di- breeding period, and social behaviours, such as rectly toward the individuals. To examine some reproduc- a complex courtship and male-male fight, both tive traits (see below), 21 adult males and eight females were hand-captured, anesthetized with lidocaine 10%, fixed described for the first time for the genus Boker- in formalin 10%, and preserved in alcohol 70% (McDi- mannohyla. Moreover, following the reccomen- armid, 1994). The 29 specimens were deposited at the CFBH (Célio F. B. Haddad) amphibian collection, Univer- dation of Pimenta et al. (2005), that researchers sidade Estadual Paulista, Rio Claro, São Paulo state, Brazil should concentrate efforts to study Data Def- (males: CFBH31743 to CFBH31763; females: CFBH31764 ficient species to obtain information on their to CFBH31771). population status, we believe that the results re- Male calling sites ported here will be extremely useful for conser- We evaluated male abundance in each type of substrate, such vation practices, but also to solve taxonomic and as leaf, trunk, branch, water, hidden places, and ground. We phylogenetic questions. measured horizontal distance from the water (DFW), height above water (HAW) and height above ground (HAG). Dis- tance to the nearest neighbor (DNN) ranged from less than 1 m to approximately 10 m, and was registered categori- Materials and methods cally:lessthan1m;1to5m;5to10mandover10m. We performed a Chi-squared test for the frequencies of less Study area than 5 m and more than 5 m, comparing the DNN between the rainy season (Oct-Mar) and dry season (Apr-Sep). We The study site is located within the Cerrado morphocli- used 5 m as a threshold because it represents the approxi- matic domain. The Cerrado is the largest, most species-rich mate mid-point of the range. During the study period, we and, probably, most threatened tropical savanna in the world found only nine females, thus we could not evaluate habitat (Silva and Bates, 2002), thus it is one of the 25 most threat- use nor distance between them. Habitat use, reproductive traits and social interactions in a stream-dweller treefrog endemic to the Brazilian Cerrado 339 Temporal distribution and temporal breeding pattern Results The numbers of calling males and active females were reg- Male calling sites and chorus structure istered every night. Rainfall (monthly accumulated rainfall) and air humidity (mean monthly air humidity) were ob- Males of B. ibitiguara were observed calling tained from the meteorological station of the municipal- only inside the gallery forests, along the streams ity of Sacramento, from the National Institute of Meteorol- covered by the canopy. They were found calling ogy (INMET), distant ca. 60 km from the study sites. Air = and water temperatures were registered at each stream ev- (i) from tree or shrub leaves (56.6%; n 129), ery night with an annalogical thermometer, from which we (ii) on trunks (21.9%; n = 50), (iii) from calculated mean monthly air and water temperatures.