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Living among thorns: herpetofaunal community (Anura and Squamata) associated to the rupicolous bromeliad Encholirium spectabile (Pitcairnioideae) in the Brazilian semi-arid Caatinga

ABSTRACT

Bromeliads are important habitats for reptiles and amphibians, and are constantly used as shelter, refuge, foraging or thermoregulation sites due to their foliar architecture, which allows for constant maintenance of humidity and temperature. This study aimed to identify the herpetofauna inhabiting the non-phytotelmata rupicolous bromeliad Encholirium spectabile Mart. ex Schult. & Schult.f. and to analyze the microhabitat usage of these bromeliads by different species in the Caatinga of northeastern Brazil. From January 2011 to August 2012, we collected data by active search throughout three paralel transects in a rock outcrop in the municipality of Santa Maria, state of Rio Grande do Norte. We recorded four species of anuran amphibians, six lizards, and seven snakes in the bromeliads. The average air temperature was lower and air humidity higher inside than outside the bromeliads, and bromeliads at the rock outcrop borders had lower temperatures and higher humidity than those at the center. We found a significant difference in the distribution of individuals throughout the rock outcrop, with most specimens found at the borders. We also found significant differences regarding the use of each microhabitat by the taxonomic groups, with lizards and snakes using green leaves and dry leaves evenly, along with fewer records in inflorescence stems, and anurans mainly using green leaves, with few records on dry leaves, and no records in the inflorescence stems. This study highlights rupicolous bromeliads as key elements in the conservation and maintenance of amphibians and reptiles in the rock outcrops of Brazilian semi-arid Caatinga.

KEY WORDS:
Amphibians; associated fauna; Bromeliaceae; habitat use; reptiles

INTRODUCTION

The Bromeliaceae family is characterized by terrestrial, epiphytic or rupicolous plants which have simple leaves organized in rosette shapes. Bromeliads are often used by animals as shelter to avoid excessive sun exposure or as a refuge against predators, due to their foliar architecture which enables relatively constant maintenance of internal humidity and temperature, creating a less stressful microhabitat when compared to the external environment (Rocha et al. 2000Rocha CFD, Cogliatti-Carvalho L, Almeida DR, Freitas AFN (2000) Bromeliads: Biodiversity amplifiers. Journal of Bromeliad Society 50: 81-83., 2004Rocha CFD, Cogliatti-Carvalho L, Freitas AFN, Pessôa TCR, Dias AS, Ariani CV, Morgado LN (2004) Conservando uma larga porção da diversidade biológica através da conservação de Bromeliaceae. Vidalia 2: 52-68.). Imbricated foliage architecture, called phytotelma, allows for accumulating water and organic debris in some species, which leads them to host large faunistic diversity (Leme 1984Leme EMC (1984) Bromélias. Ciência Hoje 3: 66-72., Benzing 2000Benzing DH (2000) Bromeliaceae: Profile of an Adaptive Radiation. Cambridge University Press, Cambridge, 710 pp., Kitching 2000Kitching RL (2000) Food Webs and Container Habitats: The Natural History and Ecology of Phytotelmata. Cambridge University Press, New York, 448 pp.). Among the subfamilies of Bromeliaceae, the occurrence of phytotelma is more frequent in bromeliads of Bromelioideae and Tillandsioideae, and only occurs in a few Pitcairnioideae species (Benzing 2000Benzing DH (2000) Bromeliaceae: Profile of an Adaptive Radiation. Cambridge University Press, Cambridge, 710 pp.). To date, studies on the fauna associated to bromeliads were focused on phytotelmata species of Bromelioidae and Tillandsioideae (e.g. Picado 1913Picado C (1913) Les broméliacées épiphytes considérées comme milieu biologique. Bulletin Scientifique France et Belgique 5: 215-360., Laessle 1961Laessle AM (1961) A microlimnological study of Jamaica bromeliads. Ecology 42: 499-517. https://doi.org/10.2307/1932236
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, Frank 1983Frank JH (1983) Bromeliad phytotelmata and their biota, especially mosquitoes. In: Frank JH, Lounibos LP (Eds) Phytotelmata: Terrestrial plants as hosts for aquatic insect communities. Plexus Publishing, Medford, 101-128., Richardson 1999Richardson BA (1999) The bromeliad microcosm and the assessment of faunal diversity in a neotropical forest. Biotropica 31: 321-336. https://doi.org/10.1111/j.1744-7429.1999.tb00144.x
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, Cruz-Ruiz et al. 2012Cruz-Ruiz GI, Mondragón D, Santos-Moreno A (2012) The presence of Abronia oaxacae (Squamata: Anguidae) in tank bromeliads in temperate forests of Oaxaca, México. Brazilian Journal of Biology 7: 337-341. http://doi.org/10.1590/S1519-69842012000200015.
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, McCracken and Forstner 2014McCracken SF, Forstner MRJ (2014) Herpetofaunal community of a high canopy tank bromeliad (Aechmea zebrina) in the Yasuní Biosphere Reserve of Amazonian Ecuador, with comments on the use on the use of “arboreal” in the herpetological literature. Amphibian & Reptile Conservation 8: 65-75.), while studies with non-phytotelmata Pitcairnioideae bromeliads are still scarce (e.g. Jorge et al. 2018Jorge JS, Rocha LHS, Jorge JPS, Sousa PHP, Santos RL, Freire EMX (2018) Floral visitors and potential pollinators of a rupicolous bromeliad (Pitcairnioideae) in the Brazilian semiarid. Neotropical Biology and Conservation 13: 101-110. https://doi.org/10.4013/nbc.2018.132.02
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).

Among vertebrates, anuran amphibians comprise the taxa most intimately associated to bromeliads, and have developed very unique relationships with these plants (Benzing 2000Benzing DH (2000) Bromeliaceae: Profile of an Adaptive Radiation. Cambridge University Press, Cambridge, 710 pp., Teixeira et al. 2006Teixeira RL, Mili PSM, Rödder D (2006) Ecology of anurans inhabiting bromeliads in a saxicolous habitat of southeastern Brazil. Salamandra 42: 155-166., Silva et al. 2011Silva HR, Carvalho ALG, Bittencourt-Silva GB (2011) Selecting a hiding place: anuran diversity and the use of bromeliads in threatened coastal sand dune habitat in Brazil. Biotropica 4: 218-227. https://doi.org/10.1111/j.1744-7429.2010.00656.x
https://doi.org/10.1111/j.1744-7429.2010...
, Sabagh et al. 2017Sabagh LT, Ferreira RB, Rocha CFD (2017) Host bromeliads and their associated frog species: further considerations on the importance of species interactions for conservation. Symbiosis 73: 201-211. https://doi.org/10.1007/s13199-017-0500-9
https://doi.org/10.1007/s13199-017-0500-...
). Bromeligenous frogs spend their entire life cycles within the bromeliad host, while bromelicolous species use the plants as a shelter and foraging place, but seek out other places to use as breeding sites (Peixoto 1995Peixoto OL (1995) Associação de anuros a bromeliáceas na Mata Atlantica. Revista da Universidade Rural, Série Ciências da Vida 17: 75-83.). Sabagh et al. (2017Sabagh LT, Ferreira RB, Rocha CFD (2017) Host bromeliads and their associated frog species: further considerations on the importance of species interactions for conservation. Symbiosis 73: 201-211. https://doi.org/10.1007/s13199-017-0500-9
https://doi.org/10.1007/s13199-017-0500-...
) conducted a literature review and identified 99 bromeligenous frog species in the world associated to 69 bromeliad hosts, with 41% of the frogs listed as threatened, highlighting a conservation priority for these bromeliads, which by consequence should protect the associated animal species.

Regarding reptiles, information about their interactions with bromeliads is still scarce. Available data in South America consists of a few autoecological studies with some lizard species or studies that investigated the whole herpetofauna inhabitant of a single bromeliad species (Vrcibradic and Rocha 1995Vrcibradic D, Rocha CFD (1995) Variação sazonal na dieta de Mabuya macrorhyncha (Sauria: Scincidae) na Restinga da Barra de Maricá, RJ. Oecologia Brasiliensis 1: 143-153., 2002Vrcibradic D, Rocha CFD (2002) Use of cacti as heat sources by thermoregulating Mabuya agilis (Raddi) and Mabuya macrorhyncha Hoge (Lacertilia, Scincidae) in two restinga habitats in southeastern Brazil. Revista Brasileira de Zoologia 19: 77-83. https://doi.org/10.1590/S0101-81752002000100005
https://doi.org/10.1590/S0101-8175200200...
, Rocha and Vrcibradic, 1998Rocha CFD, Vrcibradic D (1998) Reptiles as predators of vertebrates and as preys in a restinga habitat of southeastern Brazil. Ciência & Cultura 50: 364-368., McCracken and Forstner 2014McCracken SF, Forstner MRJ (2014) Herpetofaunal community of a high canopy tank bromeliad (Aechmea zebrina) in the Yasuní Biosphere Reserve of Amazonian Ecuador, with comments on the use on the use of “arboreal” in the herpetological literature. Amphibian & Reptile Conservation 8: 65-75.). These studies have identified bromeliads as suitable places for foraging, shelter, refuge from predators and for thermoregulation of lizards (Vrcibradic and Rocha 2002Vrcibradic D, Rocha CFD (2002) Use of cacti as heat sources by thermoregulating Mabuya agilis (Raddi) and Mabuya macrorhyncha Hoge (Lacertilia, Scincidae) in two restinga habitats in southeastern Brazil. Revista Brasileira de Zoologia 19: 77-83. https://doi.org/10.1590/S0101-81752002000100005
https://doi.org/10.1590/S0101-8175200200...
). Recently, Oliveira et al. (2019Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2019) Lizard assemblages on sandy coastal plains in southeastern Brazil: an analysis of occurrence and composition, and the role of habitat structure. Anais da Academia Brasileira de Ciências 91: e20170403. https://doi.org/10.1590/0001-3765201820170403
https://doi.org/10.1590/0001-37652018201...
) demonstrated that bromeliads are the most important microhabitat for lizard communities in coastal sandy plains (restinga ecosystems) of southeastern Brazil. Regarding snakes, data about their relationship with bromeliads is even scarcer (Henderson and Nickerson 1976Henderson RW, Nickerson MA (1976) Observations on the behavioral ecology of three species of Imantodes (Reptilia, Serpentes, Colubridae). Journal of Herpetology 10: 205-210. https://doi.org/10.2307/1562981
https://doi.org/10.2307/1562981...
, Rocha and Vrcibradic 1998Rocha CFD, Vrcibradic D (1998) Reptiles as predators of vertebrates and as preys in a restinga habitat of southeastern Brazil. Ciência & Cultura 50: 364-368., Schaefer and Duré 2011Schaefer EF, Duré MI (2011) Liophis dilepis (Lema’s Ground Snake) and Philodryas olfersii latirostris (Lichtenstein’s Green Racer). Bromeliad refugia. Herpetological Review 42: 616-617.).

Pitcairnioideae bromeliads of the Encholirium genus, popularly known as “macambiras-de-flecha” (arrow macambiras), are endemic to Brazil and occur in rock outcrops of the Caatinga and Cerrado regions. This genus presents a high diversity in the Cadeia do Espinhaço rock fields in the state of Minas Gerais, with exception of Encholirium spectabile Mart. ex Schult. & Schult.f., which occurs throughout the Caatinga in northeastern Brasil, and also in transitional areas between Caatinga and Atlantic Forest (Forzza 2005Forzza RC (2005) Revisão taxonômica de Encholirium Mart. Ex Schult. & Schult.F. (Pitcairnioideae - Bromeliaceae). Boletim de Botânica da Universidade de São Paulo 23: 1-49. https://doi.org/10.11606/issn.2316-9052.v23i1p1-49
https://doi.org/10.11606/issn.2316-9052....
, Givnish et al. 2007Givnish TJ, Millam KC, Berry P, Sytsma KJ (2007) Phylogeny, adaptive radiation, and historical biogeography of Bromeliaceae inferred from ndhF sequence data. Aliso 23: 3-26., Forzza and Zappi 2011Forzza RC, Zappi D (2011) Side by side: two remarkable new species of Encholirium Mart. ex Schult. & Schult. f. (Bromeliaceae) found in the Cadeia do Espinhaço, Minas Gerais, Brazil. Kew Bulletin 66: 281-287. https://doi.org/10.1007/s12225-011-9283-y
https://doi.org/10.1007/s12225-011-9283-...
). Despite not having phytotelma, Encholirium bromeliads have strongly aculeated leaves and form large agglomerates (patches); these characteristics ensure the formation of tangled structures which may function as a refuge for local fauna, as potential predators tend to avoid persecution into these plants due to thorn injuries on their bodies (Rocha et al. 2004Rocha CFD, Cogliatti-Carvalho L, Freitas AFN, Pessôa TCR, Dias AS, Ariani CV, Morgado LN (2004) Conservando uma larga porção da diversidade biológica através da conservação de Bromeliaceae. Vidalia 2: 52-68., Jorge et al. 2014Jorge JS, Santos RL, Almeida EA, Freire EMX (2014) First record of Hemidactylus agrius (Squamata, Gekkonidae) in thickets of Encholirium spectabile (Bromeliaceae) in the Brazilian semi-arid. Biota Amazônia 4: 176-179. https://doi.org/10.18561/2179-5746/biotaamazonia.v4n2p176-179
https://doi.org/10.18561/2179-5746/biota...
, 2018Jorge JS, Rocha LHS, Jorge JPS, Sousa PHP, Santos RL, Freire EMX (2018) Floral visitors and potential pollinators of a rupicolous bromeliad (Pitcairnioideae) in the Brazilian semiarid. Neotropical Biology and Conservation 13: 101-110. https://doi.org/10.4013/nbc.2018.132.02
https://doi.org/10.4013/nbc.2018.132.02...
).

Despite the remarkable abundance of E. spectabile patches in the semi-arid Brazilian Caatinga, and their potential as microhabitat for the herpetofauna, they have constituted poorly sampled habitats in previous studies with herpetofauna in this region, despite the local occurrence of these bromeliads in the study sites (e.g. Freire et al. 2009Freire EMX, Sugliano GOS, Kolodiuk MF, Ribeiro LB, Maggi BS, Rodrigues LS, Vieira WLS (2009) Répteis Squamata das Caatingas do seridó do Rio Grande do Norte e do cariri da Paraíba: síntese do conhecimento atual e perspectivas In: Freire EMX (Org.) Recursos Naturais das Caatingas: uma visão multidisciplinar. Editora da UFRN, Natal, 51-84., Andrade et al. 2013Andrade MJM, Sales RFD, Freire EMX (2013) Ecology and diversity of a lizard community in the semiarid region of Brazil. Biota Neotropica 13: 199-209. https://doi.org/10.1590/S1676-06032013000300023
https://doi.org/10.1590/S1676-0603201300...
, Caldas et al. 2016Caldas FL, Costa TB, Laranjeiras DO, Mesquita DO, Garda AA (2016) Herpetofauna of protected areas in the Caatinga V: Seridó Ecological Station (Rio Grande do Norte, Brazil). Check List 12: 19-29. https://doi.org/10.1590/S0101-81751 999000300022
https://doi.org/10.1590/S0101-81751...
). In this perspective, this study sought to understand the ecological relevance of thorny bromeliads as a habitat to amphibians and reptiles in the Caatinga. Our objectives were: 1) to identify the species of the herpetofauna that use E. spectabile as habitat; and 2) to evaluate the microhabitat usage of these bromeliads patches by the different herpetofaunal species, as well as differences in the use of bromeliad patches in the center and borders of the rock outcrop.

MATERIAL AND METHODS

This study was conducted at Fazenda Tanques (5.853°S, 35.701°W; datum WGS84, 137 m above sea level), in the municipality of Santa Maria, state of Rio Grande do Norte, Brazil (Fig. 1), an area included in the “Depressão Sertaneja Setentrional” ecoregion of the Caatinga (Velloso et al. 2002Velloso AL, Sampaio ESB, Pareyn FGC (2002) Ecorregiões Propostas para o bioma Caatinga. Associação Plantas do Nordeste, Instituto de Conservação Ambiental, The Nature Conservancy Brasil, Recife, 76 pp.). This ecoregion is characterized by irregular rainfall and a dry season from July to December. The climate is semi-arid, hot and dry, with an average annual precipitation of 500-800 mm/year (Velloso et al. 2002Velloso AL, Sampaio ESB, Pareyn FGC (2002) Ecorregiões Propostas para o bioma Caatinga. Associação Plantas do Nordeste, Instituto de Conservação Ambiental, The Nature Conservancy Brasil, Recife, 76 pp.). The municipality of Santa Maria is located in the “Agreste” region, a transition zone between the Caatinga and the Atlantic Forest, with characteristics of both environments (Rizzini 1997Rizzini CT (1997) Tratado de fitogeografia do Brasil: aspectos ecológicos, sociológicos e florísticos. Âmbito Cultural Edições, Rio de Janeiro, 2nd ed.). The rainy season in the “Agreste” usually extends from January to June (Velloso et al. 2002Velloso AL, Sampaio ESB, Pareyn FGC (2002) Ecorregiões Propostas para o bioma Caatinga. Associação Plantas do Nordeste, Instituto de Conservação Ambiental, The Nature Conservancy Brasil, Recife, 76 pp.). The minimum monthly temperatures in Santa Maria range from 22-24 °C, and maximum monthly temperatures from 28-32 °C, with an average annual rainfall of 781 mm (Jorge et al. 2015Jorge JS, Sales RFD, Kokubum MNC, Freire EMX (2015) On the natural history of the Caatinga Horned Frog, Ceratophrys joazeirensis (Anura: Ceratophryidae), a poorly known species of northeastern Brazil. Phyllomedusa 14: 147-156. https://doi.org/10.11606/issn.2316-9079.v14i2p147-156
https://doi.org/10.11606/issn.2316-9079....
). There is a common presence of rock outcrops with a large abundance of E. spectabile bromeliads in the study area (Figs 2-5).

Figure 1
Location of the rock outcrop where this study was conducted at Fazenda Tanques, municipality of Santa Maria, Rio Grande do Norte state, northeastern Brazil. The colored lines indicate the transects covered for data collection during the study. Red line: north border transect (T1); yellow line: center transect (T2); green line: south border transect (T3).

Figures 2-5
The Encholirium spectabile bromeliad in rock outcrops at the municipality of Santa Maria, Rio Grande do Norte state, northeastern Brazil: (2) panoramic view of bromeliad patches; (3) patch with inflorescence stems; (4) individual patch; (5) E. spectabile individual. Photos: JSJ.

The fieldwork was carried out in a large granite rock outcrop (5.855°S, 35.702°W; datum WGS84, 137 m asl) with around 5.8 ha (Fig. 1). The surroundings of this outcrop are covered by arboreal-shrubby vegetation, with the occurrence of Caatinga trees such as “juremas” (Mimosa spp.), “imburanas” (Commiphora leptophloeos (Mart.) J.B. Gillett), “cajueiros” (Anacardium occidentale L.) and “barrigudas” (Ceiba glaziovii (Kuntze) K. Schum.). Patches of E. spectabile in this rock outcrop occupy a large part of its extension (Figs 2-5). Aside from the bromeliads in the rock outcrop, the presence of “xique-xique” cactus, Pilosocereus gounellei is also common.

We sampled the rock outcrop monthly from January 2011 to August 2012, with a total of 360 hours of sample effort. Search and data collection occurred throughout three paralel transects of 12 m width and about 1500 m length, situated on the north border (T1), the center (T2) and on the south border (T3) of the outcrop (Fig. 1). All three transects were explored once per day during three consecutive days in each month by a single observer (JSJ) in the morning, afternoon, and night. Thus, each transect was surveyed once during each time of the day each month. All bromeliad patches along the transect were inspected by visual active seach, with the observer registering all specimens of the herpetofauna occupying the bromeliads in a field notebook. Each survey in the transects lasted about two hours. The absolute frequencies of each species were registered according to the number of specimens sighted. The time period that each species used the bromeliads was registered, as well as the microhabitat (see below) and behavior observed: in activity (moving through the bromeliad or motionless but with eyes open in vigilant posture) or inactive (resting and using the bromeliad as shelter).

The registered specimens were manually collected whenever possible (most cases), packed in plastic bags and identified with field numbers. In the lab, they were euthanized by cooling followed by freezing (Lillywhite et al. 2016Lillywhite HB, Shine R, Jacobson E, DeNardo DF, Gordon MS, Navas CA, Wang T, Seymour RS, Storey KB, Heatwole H, Heard D, Brattstrom B, Burghardt GM (2016) Anesthesia and euthanasia of amphibians and reptiles used in scientific research: should hypothermia and freezing be prohibited? BioScience 67: 53-61. https://doi.org/10.1093/biosci/biw143
https://doi.org/10.1093/biosci/biw143...
), fixed in formaldehyde at 10%, preserved in 70% alcohol and deposited in the Herpetological Collection of the Universidade Federal do Rio Grande do Norte - UFRN (voucher numbers are in Table 1). The capture and killing of the specimens were authorized by the Biodiversity Information and Authorization System of Chico Mendes Institute for Biodiversity Conservation (SISBIO - ICMBio, Authorization #71469-1). When a specimen was observed but not captured, the bromeliad patch was noted and not inspected again for that particular species to avoid counting the same individual again. For eleven individuals that exceeded the collection permit limits - 6 Tropidurus semitaeniatus (Spix, 1825), 4 Tropidurus hispidus (Spix, 1825) and 1 Hemidactylus agrius Vanzolini, 1978 -, we relocated them to another rock outcrop with similar physiognomy (about 12 kilometers distant) in order to avoid pseudoreplication in the sample area. This rock outcrop was previously surveyed to confirm the presence of these species. Translocations are an important tool in wildlife conservation, but need experimental testing, preparation and monitoring before being performed (Germano and Bishop 2009Germano JM, Bishop PJ (2009) Suitability of amphibians and reptiles for translocation. Conservation Biology 23: 7-15.). Although we recognize that this procedure was not the most appropriate in our study to avoid pseudoreplication, given the low number of translocated individuals, we believe that it did not compromise resident populations.

Table 1
Herpetofauna species recorded in patches of the rupicolous bromeliad Encholirium spectabile at Fazenda Tanques, municipality of Santa Maria, Rio Grande do Norte, Brazil, from January 2011 to August 2012. N: number of specimens, F: relative frequency (%); microhabitats - GL: Green Leaf, DL: Dry Leaf, IS: Inflorescence Stem.

We ramdomly selected 90 bromeliad patches to evaluate the occurrence of differences in air temperature and humidity inside and outside the bromeliads and between border and center bromeliads: 30 on the north border, 30 on the south border and 30 in the center of the rock outcrop. External air temperature and humidity were measured at 1.5 m height above the bromeliad patch, and internal air temperature and humidity in the most central bromeliad of the patch, 5 cm above the rosette center using a digital thermohygrometer (0.1 °C precision; Instrutherm® model HTR-350) with an external sensor attached (Instrutherm® model S-02K). We used independent t-tests to evaluate differences between average air temperatures and humidity inside and outside the bromeliads, as well as to compare bromeliads located at the borders and the center of the outcrop regarding these aforementioned variables.

The two-tailed χ2 test (Chi-squared test - Sokal and Rohlf 1995Sokal RR, Rohlf FJ (1995) Biometry: the principles of statistics in biological research. Freeman, New York, 887 pp.) was used to investigate differences in the bromeliad use in relation to their position in the rock outcrop (if on the borders or the center). The Kolmogorov-Smirnov two-group test (Siegel 1956Siegel S (1956) Nonparametric Statistics for the Behavioral Sciences. McGraw-Hill, New York, 312 pp.) was used to test for differences in amphibian and reptile species encountered in relation to the three locations (i.e. on the south border, north border or center) by pairs.

Microhabitat usage in the bromeliads by the amphibian and reptile species was analyzed. We previously identified that E. spectabile patches are composed of three main microhabitats: 1) Green leaves (living bromeliad leaves), 2) dry leaves (dead leaves usually situated in the base of the bromeliad), and 3) inflorescence stems. We used a loglinear analysis using the chi-squared test as the basis to analyze the different microhabitats usage of bromeliads by anuran amphibians, lizards and snakes. This analysis enables analyzing categorical data with more than two variables, constructing the interaction between such variables. The significance level assumed in all tests was 0.05.

RESULTS

We recorded 17 species of the herpetofauna inhabiting the rupicolous bromeliads (E. spectabile) at Fazenda Tanques: four anuran amphibians, six lizards, and seven snakes (Figs 6 - 19, Table 1). Lizards were more frequently recorded (77.2%, n = 149), followed by anurans (14.0%, n = 27) and snakes (8,8%, n = 17). The most frequent lizard species were the bromeliad specialist skink Psychosaura agmosticha (Rodrigues, 2000Rodrigues MT (2000) A new species of Mabuya (Squamata: Scincidae) from the semiarid caatingas of northeastern Brazil. Papéis Avulsos de Zoologia 41: 313-328.) (32.1%, n = 62), the rupicolous lava lizard T. semitaeniatus (17.6%, n = 34), and the leaf-toed gecko H. agrius (14.5%, n = 28) (Table 1).

Figures 6-9
Anuran species registered in Encholirium spectabile patches at Fazenda Tanques, municipality of Santa Maria, Rio Grande do Norte, Brazil: (6) Boana raniceps; (7) Dendropsophus nanus; (8) Scinax x-signatus; (9) Pithecopus nordestinus. Photos: JSJ.

Figures 10-15
Lizard species registered in Encholirium spectabile patches at Fazenda Tanques, municipality of Santa Maria, Rio Grande do Norte, Brazil: (10) Psychosaura agmosticha; (11) Hemidactylus agrius; (12) Gymnodactylus geckoides; (13) Phyllopezus pollicaris; (14) Tropidurus hispidus; (15) Tropidurus semitaeniatus.

Figures 16-19
Snake species registered in Encholirium spectabile patches at Fazenda Tanques, municipality of Santa Maria, Rio Grande do Norte, Brazil: (16) Epicrates assisi; (17) Oxyrhopus trigeminus; (18) Philodryas olfersii; (19) Thamnodynastes almae. Photos: JSJ.

The bromeliad usage rates by the herpetofauna on the rock outcrop borders and center revealed that the bromeliad patches located on the borders were more frequently used than the bromeliads located in the center (χ2 = 7.02, df = 1, p = 0.003). There were differences regarding the species distribution on the north border and the center (Kolmogorov-Smirnov, Dmax = 0.343, p < 0.001), and the south border and the center (Kolmogorov-Smirnov, Dmax = 0.421, p < 0.001). There was also a significant difference between the south and north borders (Kolmogorov-Smirnov, Dmax = 0.249, p < 0.001), with most specimens registered on the north border. The species that most used the center of the rock outcrop were P. agmosticha (40%) and T. semitaeniatus (37%) lizards. All anuran specimens were found in bromeliads located at the borders, with a distance less than fifteen meters from the surrounding vegetation of the rock outcrop. Except for Epicrates assisi Machado, 1945, all other snake species were only found in the borders.

The average air temperature inside the bromeliads (32.5 ± 1.3 °C, range: 29.9-34.8) was significantly lower than the average air temperature outside the bromeliads (35.5 ± 1.2 °C, range: 32.2-38.9; t = -5.139, df = 29, p = 0.003). Air humidity was higher inside (68.5 ± 1.2%, range: 59.2-79.0) than outside the bromeliads (50.9 ± 1.1%, range: 42.3-61.0), also with a significant difference (t = -4.172, df = 29, p = 0.003). In addition, the bromeliads of the borders had lower temperatures (28.7 ± 1.7 °C, range: 26.5-31.4) than those of the center of the rock outcrop (33.1 ± 1.5 °C, range: 29.9-34.8; t = -3.263, df = 29, p = 0.009), and air humidity was higher in the bromeliads of the borders (70.3 ± 1.5%, range: 58.0-79.1) than those in the center of the rock outcrop (56.3 ± 1.4%, range: 42.1-75.3; t = -3.146, df = 29, p = 0.003).

The loglinear analysis showed significant differences regarding the use of each microhabitat by the taxonomic groups (χ2 = 16.363, df = 4, p = 0.003; Likelihood Ratio = 20.121, df = 4, p < 0.001). Lizards mainly used green leaves (52.3%) and dry leaves (41.6%), with fewer records in inflorescence stems (6.1%). Similarly, snakes mainly used green leaves (47.1%) and dry leaves (47.1%), with only one record in inflorescence stems (5.9%). Anurans used mainly green leaves (92.6%), with few records on dry leaves (7.4%), and no records in inflorescence stems (Table 1, Fig. 20).

Figure 20
Use of the Encholirium spectabile microhabitats by the herpetofauna in a rock outcrop at Fazenda Tanques, municipality of Santa Maria, Rio Grande do Norte, Brazil.

DISCUSSION

We registered four anuran amphibian species and thirteen squamate reptile species associated to E. spectabile during this study, which corresponds to 17.4% of amphibians and 31% of reptiles registered for the entire study site, also including other habitats (JSJ unpublished data). Most of these species were also recorded in other sites of the Caatinga region (e.g. Pedrosa et al. 2014Pedrosa IMMC, Costa TB, Faria RG, França FGR, Laranjeiras DO, Oliveira TCSP, Palmeira CNS, Torquato S, Mott T, Vieira GHC, Garda AA (2014) Herpetofauna of protected areas in the Caatinga III: The Catimbau National Park, Pernambuco, Brazil. Biota Neotropica 14: e20140046. https://doi.org/10.1590/1676-06032014004614
https://doi.org/10.1590/1676-06032014004...
, Pereira et al. 2015Pereira EN, Teles MJL, Santos EM (2015) Herpetofauna em remanescente de Caatinga no sertão de Pernambuco, Brasil. Boletim do Museu de Biologia Mello Leitão 37: 29-43., Caldas et al. 2016Caldas FL, Costa TB, Laranjeiras DO, Mesquita DO, Garda AA (2016) Herpetofauna of protected areas in the Caatinga V: Seridó Ecological Station (Rio Grande do Norte, Brazil). Check List 12: 19-29. https://doi.org/10.1590/S0101-81751 999000300022
https://doi.org/10.1590/S0101-81751...
, Castro et al. 2019Castro DP, Mângia S, Magalhães FM, Röhr DL, Camurugi F, Silveira-Filho RR, Silva MMX, Andrade-Oliveira JA, Sousa TA, França FGR, Harris DJ, Garda AA, Borges-Nojosa DM (2019) Herpetofauna of protected areas in the Caatinga VI: the Ubajara National Park, Ceará, Brazil. Herpetology Notes 12: 727-742.), but some species that present a stronger relationship with bromeliads, such as P. agmosticha and Thamnodynastes spp., are not so frequent in herpetofaunal inventories in the Caatinga, a fact that may be related to a subsampling of rupicolous bromeliads in previous studies. The four anurans registered in E. spectabile were tree frogs of the Hylidae (3 species) and Phyllomedusidae (1 species) families, which presented a richness of thirteen species in a Caatinga-Atlantic Forest ecotone site also in the state of Rio Grande do Norte (Magalhães et al. 2013Magalhães FM, Dantas AKBP, Brito MRM, Medeiros PHS, Oliveira AF, Pereira TCSO, Queiroz MHC, Santana DJ, Silva WP, Garda AA (2013) Anurans from an Atlantic Forest-Caatinga ecotone in Rio Grande do Norte State, Brazil. Herpetology Notes 6: 1-10.). With respect to reptiles, we registered six of the ten lizard species of Gekkonidae, Phyllodactylidae, Tropiduridae and Mabuyidae, and six of the fifteen snake species of Boidae and Colubridae registered in all habitats of another Caatinga site of Rio Grande do Norte (Freire et al. 2009Freire EMX, Sugliano GOS, Kolodiuk MF, Ribeiro LB, Maggi BS, Rodrigues LS, Vieira WLS (2009) Répteis Squamata das Caatingas do seridó do Rio Grande do Norte e do cariri da Paraíba: síntese do conhecimento atual e perspectivas In: Freire EMX (Org.) Recursos Naturais das Caatingas: uma visão multidisciplinar. Editora da UFRN, Natal, 51-84., Andrade et al. 2013Andrade MJM, Sales RFD, Freire EMX (2013) Ecology and diversity of a lizard community in the semiarid region of Brazil. Biota Neotropica 13: 199-209. https://doi.org/10.1590/S1676-06032013000300023
https://doi.org/10.1590/S1676-0603201300...
). Our results, therefore, support the relevance of this non-phytotelmata rupicolous bromeliad as an important habitat for biological diversity in the Caatinga, as has been suggested for phytotelmata bromeliads in other ecosystems (Rocha et al. 1997Rocha CFD, Cogliatti-Carvalho L, Almeida DR, Freitas AFN (1997) Bromélias: ampliadoras da biodiversidade. Bromélia 4: 7-10., 2000Rocha CFD, Cogliatti-Carvalho L, Almeida DR, Freitas AFN (2000) Bromeliads: Biodiversity amplifiers. Journal of Bromeliad Society 50: 81-83., 2004Rocha CFD, Cogliatti-Carvalho L, Freitas AFN, Pessôa TCR, Dias AS, Ariani CV, Morgado LN (2004) Conservando uma larga porção da diversidade biológica através da conservação de Bromeliaceae. Vidalia 2: 52-68., Jorge et al. 2018Jorge JS, Rocha LHS, Jorge JPS, Sousa PHP, Santos RL, Freire EMX (2018) Floral visitors and potential pollinators of a rupicolous bromeliad (Pitcairnioideae) in the Brazilian semiarid. Neotropical Biology and Conservation 13: 101-110. https://doi.org/10.4013/nbc.2018.132.02
https://doi.org/10.4013/nbc.2018.132.02...
).

In the case of amphibians, the bromeliad patches were usually close to natural water bodies formed by water accumulating from rains in rock depressions. All anuran species recorded during this study were protecting themselves from sunlight during the day, or in foraging or vocalization activities during the night, which reinforces the hypotheses of the bromeliads acting as foraging site and also shelter from the sunlight, as reported for phytotelmata bromeliads (Picado 1913Picado C (1913) Les broméliacées épiphytes considérées comme milieu biologique. Bulletin Scientifique France et Belgique 5: 215-360., Peixoto 1995Peixoto OL (1995) Associação de anuros a bromeliáceas na Mata Atlantica. Revista da Universidade Rural, Série Ciências da Vida 17: 75-83., Giaretta 1996Giaretta AA (1996) Reproductive specializations of the bromeliad hylid frog Phyllodytes luteolus. Journal of Herpetology 30: 96-97. https://doi.org/10.2307/1564719
https://doi.org/10.2307/1564719...
, Rocha et al. 1997Rocha CFD, Cogliatti-Carvalho L, Almeida DR, Freitas AFN (1997) Bromélias: ampliadoras da biodiversidade. Bromélia 4: 7-10., 2004, Armbruster et al. 2002Armbruster P, Hutchinson RA, Cotgreave P (2002) Factors influencing community structure in a South American tank bromeliad fauna. Oikos 96: 225-234. https://doi.org/10.1034/j.1600-0706.2002.960204.x
https://doi.org/10.1034/j.1600-0706.2002...
, Oliveira et al. 2017Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2017) Local environmental factors influence the structure of frog communities on the sandy coastal plains of southeastern Brazil. Herpetologica 73: 307-312. https://doi.org/10.1655/Herpetologica-D-16-00075.1
https://doi.org/10.1655/Herpetologica-D-...
). Aside from providing shelter, the bromeliads also function as a display arena for males during the anuran reproductive season, with the best territories defended from intruding males (JSJ personal observation). Defense of territories by males also occurs in other species of the Hylidae family (Pombal and Haddad 2007Pombal JP Jr, Haddad CFB (2007) Estratégias e modos reprodutivos em anuros. In: Nascimento LB, Oliveira ME (Eds) Herpetologia no Brasil II. Sociedade Brasileira de Herpetologia, Belo Horizonte, 101-116., Uetanabaro et al. 2008Uetanabaro M, Prado CPA, Rodrigues DJ, Gordo M, Campos Z (2008) Guia de Campo de Anuros do Pantanal Sul e Planaltos de Entorno. Editora UFMS, Campo Grande, 196 pp.). In the study site, E. spectabile bromeliads grow on water body edges, which form naturally by the rock depressions, forming suitable sites for species that reproduce in these environments and creating conditions that would not exist without their presence. Many males of the four registered species focus on these bromeliads as perches to vocalize during the months of the reproductive season, forming large reproductive groups, and the presence of spawning and tadpoles in the ponds confirmed this hypothesis (JSJ, pers. obs.). Thus, although E. spectabile bromeliads cannot function as sites for depositing and developing eggs due to an absence of phytotelma, males use them as display sites.

Bromeliads provide relatively higher humidity than the external environment because they can retain water in their leaf axils, as well as forming a shaded region due to their foliar architecture (Picado 1913Picado C (1913) Les broméliacées épiphytes considérées comme milieu biologique. Bulletin Scientifique France et Belgique 5: 215-360., Oliveira et al. 1994Oliveira MGN, Rocha CFD, Bagnall T (1994) A comunidade animal associada à bromélia tanque Neoregelia cruenta (R. Graham) L.B. Smith. Bromélia 1: 22-29., Peixoto 1995Peixoto OL (1995) Associação de anuros a bromeliáceas na Mata Atlantica. Revista da Universidade Rural, Série Ciências da Vida 17: 75-83., Rocha et al. 2004Rocha CFD, Cogliatti-Carvalho L, Freitas AFN, Pessôa TCR, Dias AS, Ariani CV, Morgado LN (2004) Conservando uma larga porção da diversidade biológica através da conservação de Bromeliaceae. Vidalia 2: 52-68., Silva et al. 2011Silva HR, Carvalho ALG, Bittencourt-Silva GB (2011) Selecting a hiding place: anuran diversity and the use of bromeliads in threatened coastal sand dune habitat in Brazil. Biotropica 4: 218-227. https://doi.org/10.1111/j.1744-7429.2010.00656.x
https://doi.org/10.1111/j.1744-7429.2010...
, Ferreira et al. 2012Ferreira RB, Schineider JAP, Teixeira RL (2012) Diet, fecundity, and use of bromeliads by Phyllodytes luteolus (Anura: Hylidae) in southeastern Brazil. Journal of Herpetology 46: 19-24., Oliveira et al. 2017Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2017) Local environmental factors influence the structure of frog communities on the sandy coastal plains of southeastern Brazil. Herpetologica 73: 307-312. https://doi.org/10.1655/Herpetologica-D-16-00075.1
https://doi.org/10.1655/Herpetologica-D-...
). Our results support the presence of this feature in E. spectabile, because the temperature inside the bromeliads was significantly lower and humidity was higher than in the external environment. Additionally, the bromeliads located in the rock outcrop borders presented milder temperatures than those in the center, as well as higher humidity. Besides the fact that most water bodies (ponds) were located at the borders, contributing to a higher humidity in these areas, the vegetation on the borders likely creates a less stressful environment for the herpetofauna because bromeliads located in the borders are usually in a shaded area. In this sense, the fact that all anuran specimens were occupying bromeliads in the rock outcrop borders is probably related to physiological characteristics of this group, since amphibians depend on relatively high humidity and water availability to perform their metabolic functions (Wells 2007Wells KD (2007) The ecology and behavior of amphibians. University of Chicago Press, Chicago, 1148 pp.). Regarding lizards, their distribution in the rock outcrop borders may be related to greater prey availability, since their diets are mainly based on arthropods (Pianka 1973Pianka ER (1973) The structure of lizard communities. Annual Review Ecology Systematics 4: 53-74. https://doi.org/10.1146/annurev.es.04.110173.000413
https://doi.org/10.1146/annurev.es.04.11...
, Vanzolini et al. 1980Vanzolini PE, Ramos-Costa AMA, Vitt LJ (1980) Répteis das Caatingas. Academia Brasileira de Ciências, Rio de Janeiro, 161 pp., Sales et al. 2012Sales RFD, Ribeiro LB, Jorge JS, Freire EMX (2012) Feeding habits and predator-prey size relationships in the whiptail lizard Cnemidophorus ocellifer (Teiidae) in the semiarid region of Brazil. South American Journal of Herpetology 7: 149-156. https://doi.org/10.2994/057.007.0204
https://doi.org/10.2994/057.007.0204...
, Oliveira et al. 2019Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2019) Lizard assemblages on sandy coastal plains in southeastern Brazil: an analysis of occurrence and composition, and the role of habitat structure. Anais da Academia Brasileira de Ciências 91: e20170403. https://doi.org/10.1590/0001-3765201820170403
https://doi.org/10.1590/0001-37652018201...
). Prey availability for lizards possibly come from the arboreal-shrubby vegetation present in the rock outcrop borders, leading the species to aggregate in these areas.

The lizard species recorded in E. spectabile during this study are similar to the families and genera recorded for tank bromeliads in other Brazilian ecosystems, demonstrating a tendency towards the use of bromeliads by these taxa (Vrcibradic and Rocha 2002Vrcibradic D, Rocha CFD (2002) Use of cacti as heat sources by thermoregulating Mabuya agilis (Raddi) and Mabuya macrorhyncha Hoge (Lacertilia, Scincidae) in two restinga habitats in southeastern Brazil. Revista Brasileira de Zoologia 19: 77-83. https://doi.org/10.1590/S0101-81752002000100005
https://doi.org/10.1590/S0101-8175200200...
, Santos et al. 2003Santos RL, Almeida MG, Nunes JV (2003) Water-holding bromeliads as a keystone resource for a gecko (Briba brasiliana Amaral 1935, Sauria, Gekkonidae) in restinga habitats in northeastern Brazil. Journal of the Bromeliad Society 53: 84-88., Rocha et al. 2004Rocha CFD, Cogliatti-Carvalho L, Freitas AFN, Pessôa TCR, Dias AS, Ariani CV, Morgado LN (2004) Conservando uma larga porção da diversidade biológica através da conservação de Bromeliaceae. Vidalia 2: 52-68., Oliveira et al. 2017Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2017) Local environmental factors influence the structure of frog communities on the sandy coastal plains of southeastern Brazil. Herpetologica 73: 307-312. https://doi.org/10.1655/Herpetologica-D-16-00075.1
https://doi.org/10.1655/Herpetologica-D-...
, 2019Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2019) Lizard assemblages on sandy coastal plains in southeastern Brazil: an analysis of occurrence and composition, and the role of habitat structure. Anais da Academia Brasileira de Ciências 91: e20170403. https://doi.org/10.1590/0001-3765201820170403
https://doi.org/10.1590/0001-37652018201...
). For example, in the coastal Atlantic Forest restingas of northeastern and southeastern Brazil, there is common occurrence of the skink Psychosaura macrorhyncha (Hoge, 1946), a species which is very morphologically and phylogenetically close to P. agmosticha (Miralles and Carranza 2010Miralles A, Carranza S (2010) Systematics and biogeography of the Neotropical genus Mabuya, with special emphasis on the Amazonian skink Mabuya nigropunctata (Reptilia, Scincidae). Molecular Phylogenetics and Evolution 54: 857-886. http://doi.org/10.1016/j.ympev.2009.10.016.
http://doi.org/10.1016/j.ympev.2009.10.0...
), and both species share habitat specialization to bromeliads (Rodrigues 2000Rodrigues MT (2000) A new species of Mabuya (Squamata: Scincidae) from the semiarid caatingas of northeastern Brazil. Papéis Avulsos de Zoologia 41: 313-328.). The geckos Gymnodactylus geckoides Spix, 1825 and Hemidactylus brasilianus (Amaral, 1935) were recorded in the foliage of the tank bromeliads Hohenbergia and Aechmea in Atlantic Forest areas along the coast of Rio Grande do Norte (Freire 1996Freire EMX (1996) Estudo ecológico e zoogeográfico sobre a fauna de Lagartos (Sauria) das dunas de Natal, Rio Grande do Norte e da restinga de Ponta de Campina, Cabedelo, Paraíba, Brasil. Revista Brasileira de Zoologia 13(4): 903-921. https://doi.org/10.1590/S0101-81751996000400012
https://doi.org/10.1590/S0101-8175199600...
, Santos et al. 2003Santos RL, Almeida MG, Nunes JV (2003) Water-holding bromeliads as a keystone resource for a gecko (Briba brasiliana Amaral 1935, Sauria, Gekkonidae) in restinga habitats in northeastern Brazil. Journal of the Bromeliad Society 53: 84-88.), as well as for lava lizards of the genus Tropidurus (Oliveira et al. 1994Oliveira MGN, Rocha CFD, Bagnall T (1994) A comunidade animal associada à bromélia tanque Neoregelia cruenta (R. Graham) L.B. Smith. Bromélia 1: 22-29.) and geckos of the genus Phyllopezus recorded in soil bromeliads of restingas (Vanzolini 1968Vanzolini PE (1968) Geography of the South American Gekkonidae (Sauria). Arquivos de Zoologia 17: 85-112.).

A similar pattern was found for snakes, because the richness found in this study is very similar to that found in studies with tank bromeliads. Lygophis dilepis Cope, 1862, Oxyrhopus petola Linnaeus, 1758, Philodryas olfersii (Lichtenstein, 1823) and Thamnodynastes cf. pallidus were recorded in restingas of Rio de Janeiro state, southeastern Brazil, using bromeliads as a foraging site (Rocha and Vrcibradic 1998Rocha CFD, Vrcibradic D (1998) Reptiles as predators of vertebrates and as preys in a restinga habitat of southeastern Brazil. Ciência & Cultura 50: 364-368., Schaefer and Duré 2011Schaefer EF, Duré MI (2011) Liophis dilepis (Lema’s Ground Snake) and Philodryas olfersii latirostris (Lichtenstein’s Green Racer). Bromeliad refugia. Herpetological Review 42: 616-617.), and Leptodeira annulata (Linnaeus, 1758) in epiphytic bromeliads in Ecuador (McCracken and Forstner 2014McCracken SF, Forstner MRJ (2014) Herpetofaunal community of a high canopy tank bromeliad (Aechmea zebrina) in the Yasuní Biosphere Reserve of Amazonian Ecuador, with comments on the use on the use of “arboreal” in the herpetological literature. Amphibian & Reptile Conservation 8: 65-75.). Most snake species recorded in this study feed on small amphibians and lizards (Vitt and Vangilder 1983Vitt LJ, Vangilder LD (1983) Ecology of snake community in the northeastern Brazil. Amphibia-Reptilia 4: 273-296. https://doi.org/10.1163/156853883X00148
https://doi.org/10.1163/156853883X00148...
, Vanzolini et al. 1980Vanzolini PE, Ramos-Costa AMA, Vitt LJ (1980) Répteis das Caatingas. Academia Brasileira de Ciências, Rio de Janeiro, 161 pp., Mesquita et al. 2013Mesquita PC, Passos MD, Passos DC, Borges-Nojosa DM, Cechin SZ (2013) Ecologia e história natural das serpentes de uma área de Caatinga no nordeste brasileiro. Papeis Avulsos de Zoologia 53: 99-113. http://doi.org/10.1590/S0031-10492013000800001
http://doi.org/10.1590/S0031-10492013000...
). The concentration of amphibians and lizards in the borders possibly causes the snakes to remain in the bromeliads located in the borders as a foraging strategy. Some studies on snake diets in bromeliad habitats have confirmed the importance of bromeliads as a foraging site, and amphibian and lizards as prey for these species (Dunn 1937Dunn ER (1937) The amphibian and reptilian fauna of bromeliads in Costa Rica and Panama. Copeia 3: 163-167. https://doi.org/10.2307/1436136
https://doi.org/10.2307/1436136...
, Beebe 1946Beebe W (1946) Field notes on the snakes of Kartabo, British Guiana, and Caripito, Venezuela. Zoologica 31: 11-52., Landry et al. 1966Landry MJ, Langebartel DA, Moll EO, Smith HM (1996) A collection of snakes from Volcan Tacana, Chiapas, Mexico. Journal of the Ohio Herpetological Society 5: 93-101. https://doi.org/10.2307/1562612
https://doi.org/10.2307/1562612...
, Henderson and Nickerson 1976Henderson RW, Nickerson MA (1976) Observations on the behavioral ecology of three species of Imantodes (Reptilia, Serpentes, Colubridae). Journal of Herpetology 10: 205-210. https://doi.org/10.2307/1562981
https://doi.org/10.2307/1562981...
). The record of the boid snake Epicrates assisi deserves special mention, since it is a large snake widely distributed throughout the Caatinga and was registered for the first time in bromeliads. This species feeds on small mammals, birds and lizards (Vanzolini et al. 1980Vanzolini PE, Ramos-Costa AMA, Vitt LJ (1980) Répteis das Caatingas. Academia Brasileira de Ciências, Rio de Janeiro, 161 pp.). A possible reason for occupying bromeliads by this species is the large number of small rodents that live among E. spectabile patches (JSJ, personal observation), such as the Brazilian guinea pig, Galea spixii (Wagler, 1831), and the common “punaré”, Thrichomys apereoides (Lund, 1839), in addition to nests of the Picui ground-dove, Columbina picui (Temminck, 1813), which constitute potential prey items in the diet of E. assisi in the study area.

With respect to the use of microhabitats of E. spectabile by the herpetofauna, dry leaves, usually situated in the base of the bromeliads, seem to be used mainly as shelter from predators; for instance, lava lizards (T. hispidus and T. semitaeniatus), which used mainly this microhabitat (Table 1), usually run to the bases of bromeliads in response to human approach (JSJ personal observation). Green leaves, on the other hand, constitute the most used microhabitat by most species (Table 1, Fig. 20), functioning as foraging and thermoragulating sites by the herpetofauna, and also as display sites by males of anurans, as previously stated. Inflorescence stems were used only by a few species of lizards and snakes (Table 1), and probably function as foraging sites since the flowers attract several arthropod species (Jorge et al. 2018Jorge JS, Rocha LHS, Jorge JPS, Sousa PHP, Santos RL, Freire EMX (2018) Floral visitors and potential pollinators of a rupicolous bromeliad (Pitcairnioideae) in the Brazilian semiarid. Neotropical Biology and Conservation 13: 101-110. https://doi.org/10.4013/nbc.2018.132.02
https://doi.org/10.4013/nbc.2018.132.02...
).

Oliveira et al. (2017Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2017) Local environmental factors influence the structure of frog communities on the sandy coastal plains of southeastern Brazil. Herpetologica 73: 307-312. https://doi.org/10.1655/Herpetologica-D-16-00075.1
https://doi.org/10.1655/Herpetologica-D-...
) demonstrated the importance of bromeliads for anuran communities in restinga habitats of the southeastern Brazilian coast. The authors highlight that the presence of bromeliads promoted the structuring of the anuran community, mainly through the availability of spawning sites. Similar results were found by Silva et al. (2011Silva HR, Carvalho ALG, Bittencourt-Silva GB (2011) Selecting a hiding place: anuran diversity and the use of bromeliads in threatened coastal sand dune habitat in Brazil. Biotropica 4: 218-227. https://doi.org/10.1111/j.1744-7429.2010.00656.x
https://doi.org/10.1111/j.1744-7429.2010...
) for anurans in coastal habitats, where they highlight the importance of accumulated water in phytothelma, mainly due to the characteristics of restingas, where the lack of water is a limiting factor, and the bromeliads provide such resource. In addition, Oliveira et al. (2019Oliveira JCF, Winck GR, Ribeiro JP, Rocha CFD (2019) Lizard assemblages on sandy coastal plains in southeastern Brazil: an analysis of occurrence and composition, and the role of habitat structure. Anais da Academia Brasileira de Ciências 91: e20170403. https://doi.org/10.1590/0001-3765201820170403
https://doi.org/10.1590/0001-37652018201...
) demonstrated that bromeliads play a crucial role in the structuring of lizard communities by providing adequate sites for thermoregulation, and providing food (small invertebrates) and shelter for small species or juveniles. We suggest that similar factors may be acting in the herpetofauna of the Fazenda Tanques in the Caatinga of Rio Grande do Norte, but not due to a provision of water though phytotelma as in tank bromeliads of restingas, but because they offer other resources and conditions, such as shelter, thermoregulation sites and food availability (small invertebrates) for anurans and lizards, which eventually can attract snakes (predators of anurans and lizards). Thus, as proposed by Rocha et al. (2000Rocha CFD, Cogliatti-Carvalho L, Almeida DR, Freitas AFN (2000) Bromeliads: Biodiversity amplifiers. Journal of Bromeliad Society 50: 81-83., 2004Rocha CFD, Cogliatti-Carvalho L, Freitas AFN, Pessôa TCR, Dias AS, Ariani CV, Morgado LN (2004) Conservando uma larga porção da diversidade biológica através da conservação de Bromeliaceae. Vidalia 2: 52-68.) for tank bromeliads in the Atlantic Forest, we suggest that the rupicolous bromeliads in the Caatinga are key elements in the conservation and maintenance of a wide variety of organisms associated to it.

Encholirium deserves more prominence in the national conservation policies, not only because it is endemic to Brazil, which in itself should already guarantee special attention, but because it is vulnerable to extinction. According to Forzza et al. (2003Forzza RC, Christianini AV, Wanderley MGL, Buzato S (2003) Encholirium (Piticairnioideae - Bromeliaceae): conhecimento atual e sugestões para conservação. Vidalia 1: 7-20.), 20 of the 23 species of the genus do not occur inside protected areas, and their habitat (rock outcrops) is threatened by mining activities. Regarding the bromeliad characteristics as a key species for conservation (Rocha et al. 1997Rocha CFD, Cogliatti-Carvalho L, Almeida DR, Freitas AFN (1997) Bromélias: ampliadoras da biodiversidade. Bromélia 4: 7-10.), the Encholirium genus fits in without question in this context, whereby conserving the species of this genus is also a way of conserving all the biodiversity that is interconnected to them. In the face of the strong pressure that the Caatinga has been facing, mainly due to the constant deforestation (Silva and Barbosa 2017Silva J, Barbosa LCF (2017) Impact of human activities on the Caatinga. In Silva J, Leal I, Tabarelli M (Eds) Caatinga: The largest tropical dry forest region in South America. Springer, Cham, 359-368.), we draw attention to the need for conservation of this region and all the biota that inhabits it, including the rupicolous bromeliads and all the associated fauna.

ACKNOWLEDGMENTS

This study was supported by research grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico to JSJ (process 130363/2014-6) and EMXF (process 313661/2017-0) and from Coordernação de Aperfeiçoamento de Pessoal de Nível Superior to RFDS (process 1558610). We also thank the employees of the Fazenda Tanques through Mr Toinho for their support in the field and to all others who helped by contributing feedback to improve the manuscript. We also thank two anonymous reviewers for helpful comments on the manuscript.

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Publication Notes

  • Available online:

    June 3, 2020
  • Zoobank Register:

    http://zoobank.org/FC9B791B-AE36-4C27-95F6-8F5A3DAE38FC
  • Publisher:

    © 2020 Sociedade Brasileira de Zoologia. Published by Pensoft Publishers at https://zoologia.pensoft.net

Edited by

Editorial responsibility:

Fabricius M.C.B. Domingos

Publication Dates

  • Publication in this collection
    19 June 2020
  • Date of issue
    2020

History

  • Received
    17 Sept 2019
  • Accepted
    28 Jan 2020
  • Published
    03 June 2020
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