Herpetology Notes, volume 13: 113-123 (2020) (published online on 11 February 2020) Diet composition of Lysapsus bolivianus Gallardo, 1961 (Anura, Hylidae) of the Curiaú Environmental Protection Area in the Amazonas river estuary Mayara F. M. Furtado1 and Carlos E. Costa-Campos1,* Abstract. Information on a species’ diet is important to determine habitat conditions and resources and to assess the effect of preys on the species distribution. The present study aimed describing the diet of Lysapsus bolivianus in the floodplain of the Curiaú Environmental Protection Area. Individuals of L. bolivianus were collected by visual search in the floodplain of the Curiaú River. A total of 60 specimens of L. bolivianus were euthanized with 2% lidocaine, weighed, and their stomachs were removed for diet analysis. A total of 3.020 prey items were recorded in the diet. The most representative preys were: Diptera (36.21%), Collembola (16.61%), and Hemiptera (8.31%), representing 73.20% of the total consumed prey. Based on the Index of Relative Importance for males, females, and juveniles, the most important items in the diet were Diptera and Collembola. The richness of preys recorded in the diet of L. bolivianus in the dry season was lower than that of the rainy season. Regarding prey abundance and richness, L. bolivianus can be considered a generalist species and a passive forager, with a diet dependent on the availability of preys in the environment. Keywords. Amphibia; Eastern Amazon, Niche overlap, Predation, Prey diversity, Pseudinae Introduction (Toft 1980; 1981; Donnelly, 1991; López et al., 2009; López et al., 2015). The diet of most anuran species is composed mainly of The genus Lysapsus Cope, 1862 is restricted to South arthropods and because of the opportunistic behaviour of America and comprises aquatic and semi-aquatic anurans many species, anurans are usually regarded as generalist inhabiting temporary or permanent ponds with large predators (Duellman and Trueb, 1994). Data on diet of quantities of aquatic vegetation (Prado and Uetanabaro, anurans can help to understand life history, identify 2000; Garda et al., 2007). The genus Lysapsus includes environmental conditions and consequences of habitat four species: L. bolivianus Gallardo, 1961, L. caraya alterations (e.g., different stages of deforestation), Gallardo, 1964, L. limellum Cope, 1862, and L. laevis prey species distribution, and reasons for population (Parker, 1935) (Aguiar-Jr et al., 2007). These species are fluctuations (Lips et al., 2005; López et al., 2015). distributed in the basins of Amazon River, Tocantins- Anuran feeding mechanisms evolved in response to Araguaia, Paraná river, and the Rupununi savannahs, selective pressures and phylogenetic constraints, such respectively (Garda et al., 2010) that diets are influenced by morphology, physiology, and Lysapsus bolivianus Gallardo 1961 is a diurnal and behaviour (Toft, 1980). Prey availability of appropriate nocturnal species with snout-vent length (SVL) up to types and sizes is a factor that influences the diet of 20.2 mm in males and 23.5 mm in females, found in anurans, but few studies have assessed prey availability the water surface on loose clusters of emergent aquatic in the environment to allow interpretation of the results vegetation (Bosch et al., 1996). Males call from a horizontal position on leaves of aquatic macrophytes (Furtado et al., 2014). The species is listed as Data Deficient by the IUCN Red List of Threatened Species, and there is little information on its extent of occurrence, 1 Universidade Federal do Amapá, Departamento de Ciências status and ecological requirements (Angulo, 2008). Biológicas e da Saúde, Laboratório de Herpetologia. Rod. JK Km 2, Bairro Jardim Marco Zero, CEP 68902-280, Macapá, In this study we describe aspects of the diet of L. Amapá. bolivianus in a floodplain area of northern Brazil, eastern * Corresponding author. Email: [email protected] Amazonia in order to: (1) determine diet composition in 114 Mayara F. M. Furtado & Carlos E. Costa-Campos adult and juveniles; (2) assess possible differences in the numerical and volumetric percentages of each prey diet composition according to life stage and sex, and (3) category were determined for pooled stomachs. We determine if there is seasonal variation in diet. calculated an index of relative importance (IRI) for each prey taxon using the sum of the percentages of number Materials and Methods (N%), frequency (F%) and volume (V%): IRI = F (%) + N (%) + V (%) / 3 (Biavati et al., 2004). The study was conducted in a temporary pond located The niche breadth was calculated using the percentage in Toca da Raposa Farm (0.15019º N; 51.03847º W) of each prey item in the stomach, according to the and inserted in Curiaú Environmental Protection Area, formula: B = [(Σ P2 )-1 - 1] (n - 1)-1, where B = north of the municipality of Macapá. The climate of the a j ij a standardized trophic niche breadth; P = proportion of region is Equatorial (Am) according Köppen-Geiger ij food category j in the diet of species i; n = total number classification (Alvares et al., 2014) and the average of food categories. The standardized Levin’s index for temperature is 35.2 °C, varying seasonally between niche breadth was used (Krebs, 1999), which varies 27.6 to 41.0 °C. The dry season goes from August to from 0 (exclusive use of a single prey category) to 1 December (160 mm) and the rainy season begins in (equal use of all prey categories). January, reaching the highest rainfall in March and July, The food niche overlap between sexes was calculated with annual average of 1.530 mm (NHMET, 2012). using Pianka’s symmetric index (Pianka, 1973) as given We carried out our sampling by active visual search by the equation O = ∑ P P /√∑ P 2 ∑ P 2, where from October 2011 to September 2012. Three researchers jk ij * ik ij * ik j and k refer to the two sexes under comparison, O – walked in a straight line the five transects of 1 km each jk niche overlap, P – proportion of food component i. The (50 m apart from one another), in floating vegetation i index ranges from 0 to 1, with 1 indicating complete composed of Nymphoides indica (L.) Kuntze and overlap (Krebs, 1999). Salvinia auriculata Aubl (Crump and Scott Jr., 1994). We performed Statistical tests using BioEstat 5.3 We collected a total of 60 individuals of L. bolivianus, software (Ayres et al., 2007) at a significance level of p totalling 144 hours of sampling. ≤ 0.05. Before performing parametric tests, all variables In the laboratory, measurements of SVL were obtained were tested for normality and homoscedasticity of with a digital calliper (precision 0.01 mm). Frogs’ sex variances. We tested for differences between males, was determined based on the presence of secondary females and juveniles in the number of prey and in sexual traits (vocal sac for males) or by direct observation the mean prey volume consumed per frog using one- of gonads. The females were considered adult when way analysis of variance (ANOVA). We compared the their ovaries were convolutes and enlarged. Individuals sizes (SVL) of both sexes by using the Kruskal-Wallis lacking these characteristics were considered juveniles. test. The niche breadth was analysed with the software For the diet analysis, collected specimens were Ecological Methodology (Krebs, 1999) and the niche euthanized with anaesthetic (2% lidocaine), fixed with overlap, with the software EcoSim 7.0 (Gotelli and 10% formalin, and preserved in 70% ethanol, according Entsminger, 2001). to Heyer et al. (1994). Data on diet were obtained through the analysis of stomach content of dissected Results specimens and prey items were identified to the Order level. We identified preys according with identification Diet composition.—We examined the stomach keys by Borror and Delong (2011) and Rafael et al. contents of 60 individuals of L. bolivianus (25 males, (2012). Anurans voucher specimens were deposited in 22 females, and 13 juveniles). Females (SVL 19.8 ± 1.4 the herpetological collection of Universidade Federal mm, range: 16.4–23.5 mm) were significantly larger do Amapá. than males (SVL 17.6 ± 1.1 mm, range: 14.1–20.8 mm; We measured length and width for all prey items Kruskal Wallis 12.0433; p < 0.0001). Juveniles varied in under stereomicroscopes with graduated oculars and SVL from 12.7 to 16.9 mm (15.5 ± 0.9 mm). their volumes were estimated using the equation for an We recorded a total of 3.020 items with a mean of 50.3 ellipsoid (cf. Vitt and Zani 2005): V = 4/3 π (length/2) preys per stomach. The most frequent prey items were (width/2)2. The frequency of items consumed (number Diptera (35.7%), Collembola (17.7%), and Hemiptera of stomachs containing the prey item), frequency of (8.2%), representing 60.8% of the total consumed prey occurrence (number of stomachs containing the prey (Table 1). These prey categories also presented higher category i, divided by the total number of stomachs) and IRI values (Table 1). Diet compositionof Table 1. Food items found in the stomach of 60 specimens (adults and juveniles) of Lysapsus bolivianus collected in a temporary pond located in Toca da Raposa Farm and inserted in a Curiaú Table 1 – Food items found in the stomach of 60 specimens (adults and juveniles) of Lysapsus bolivianus collected in a temporary pond located in Toca da Raposa Farm and inserted in a EnvironmentalCuriaú Environmental Protection Area.Protection SVL Area. = snout-vent-length, SVL = snout-vent-length, N = number N = of number items consumed,of items consumed, N% = numerical N% = numerical percentage percentage of items, of F items, = frequency F = frequency of items of consumed, items consumed, F% frequency F% frequency of occurrence, of V = volumeoccurrence, of items V = volume consumed, of items V% consumed, numerical V% percentage numerical of percentageitems, IRI of= indexitems, ofIRI relative = index importance of relative importancefor each category for each of category items in of the items diet, in NIA the diet, = non-identified NIA = non-identified arthropods.