Zootaxa 4732 (4): 589–592 https://www.mapress.com/j/zt/ Copyright © 2020 Magnolia Press ISSN 1175-5326 (print edition) Correspondence ZOOTAXA ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4732.4.9 http://zoobank.org/urn:lsid:zoobank.org:pub:FFF97BB8-E31F-4940-B559-60148D6EF685 Description of two calls of Eleutherodactylus rubrimaculatus (Anura: Eleutherodactylidae) in Chiapas, Mexico ANGELA M. MENDOZA-HENAO1,2, RAQUEL HERNÁNDEZ-AUSTRIA1,2, ALDO LÓPEZ-VELÁZQUEZ1,2 & GABRIELA PARRA-OLEA1,3 1 Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, PO 70-153, 04510 Mexico City, Mexico. 2 Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, PO 70-153, 04510, Mexico City, Mexico 3 Corresponding author: E-mail: gparra@ib.unam.mx Frogs of the genus Eleutherodactylus are direct developing frogs grouped into five subgenera and 192 species, with a geographic distribution primarily centered in the Caribbean (Padial et al. 2014). Eleutherodactylus species inhabit a variety of environments such as tropical and temperate forests, and scrub, where they occupy different microhabitats including caves, floors rich in leaf litter, cracks and cavities of limestone and volcanic outcrops (Reyes-Velasco et al. 2015). Mexico harbors 33 species of Eleutherodactylus (AmphibiaWeb 2018), most of them distributed in central-western and southwestern Mexico (Reyes-Velasco et al. 2015). The Red-spotted Chirping Frog or Dusky Chirping Frog Eleutherodactylus rubrimaculatus (Taylor & Smith 1945) is restricted to extreme south eastern Chiapas, Mexico, a region considered one of the areas with a highest alpha diversity of amphibians in Mexico and high degree of endemisms (Campbell 1999; Pineda & Lobo 2009). Eleutherodactylus rubrimaculatus can be found from 0–700 masl, inhabiting cloud forests but is also known to occur in modified habitats including palm groves and grasslands (Santos-Barrera & Canseco-Márquez 2004). Despite the fact that is locally abundant, this species is considered Vulnerable according to IUCN (Santos-Barrera & Canseco-Márquez 2004) due to its small range. Although it was recently included in a study about the molecular systematics of continental Eleutherodactylus (Grünwald et al. 2018), to date there are no studies of its biology, ecology, and behavior. The taxonomy of Eleutherodactylus species is still problematic due to their conserved external morphology (Padial et al. 2014), hence, detailed descriptions of advertisement calls may aid integrative approaches, targeted at clarifying their taxonomic status (e.g. Padial & De La Riva 2009). Anuran calls are important in species recognition and reproduction and are a valuable tool for taxonomic identification (Köhler et al. 2017). However, most studies in anuran acoustics are focused on the advertisement call, and less information is available for other calls such as courtship, territorial, or alarm calls. Less than 1% of the known species of frogs and toads do females vocalize in reproductive contexts (Gerhardt & Bee 2007) and reports on this phenomenon have mostly been anecdotal. Herein, we describe the previously unknown advertisement calls and a second calls of E. rubrimaculatus. Individuals of E. rubrimaculatus were detected by acoustic and visual surveys at night in cloud forest in the Escuintla municipality in the state of Chiapas, Mexico (15°25’7” N, 92°34’45.6” W; 562 masl) on June 2017 and June 2018, in vegetation on the side of a dirt road. The species could be unambiguously identified by its size and the dorsal reddish spots on the dorsum of the specimens (Fig. 1a). Between 3 and 12 calls (mean = 7.9) per individual were recorded at 1-meter distance, with a digital recorder (Tascam DR-40) and a unidirectional microphone (Sennheisser K6/ME 66) and it was stored as wave files at a sampling rate of 44.1 kHz and an amplitude resolution of 16 bits. We measured air temperature shortly after the individuals were recorded with a digital thermometer (Benetech GM300, resolution 0.1°C). The air temperature was measured as close as possible at the same heights as the calling sites of the individual recorded. Voucher specimens were fixed with 10% formalin and deposited at the Colección Nacional de Anfibios y Reptiles (CNAR), Instituto de Biología, UNAM under the numbers IBH31782—31784, and the recordings were deposited in both the Colección de cantos of CNAR and the Colección digital de cantos grabados of Museo de Zoología de la Facultad de Ciencias, UNAM with the same IBH voucher number. Calls were identified using the software Raven Pro 1.4 (Bioacustics Research Program, 2011) and the spectrogram was constructed with a Blackman algorithm and a windows size of 5 ms and 80% overlap. We generated call figures us- Accepted by P. Gambale: 9 Jan. 2020; published: 14 Feb. 2020 589 ing Seewave v. 1.6 package (Sueur et al. 2008). From the spectrogram, we obtained the dominant frequency, bandwidth, and the mean frequency of the first harmonic. Temporal parameters were measured from the waveform. Additionally, to include information about call complexity, important for species recognition (Ryan 1983), we used the package warbleR (Araya-Salas & Smith-Vidaurre 2017) to extract two additional parameters of the individual calls as a quantitative metric of the modulation: dfslope and modindx. The df slope is calculated as the change in dominant frequency through time in Hz/s. It gives us an idea of the frequency spectrum based on the start and end of the signal. The modulation index is the cumulative absolute difference between adjacent measurements of dominant frequencies divided by the dominant frequency range (1 means the signals is not modulated). For call terminology we followed Köhler et al. (2017). The frogs were observed calling on the shrubs between 20 and 100 cm above the ground, at a mean air temperature of 22.3 ± 1.2 °C (mean ± SD). The vocal display in E. rubrimaculatus included two types of auditory signals (Fig. 1b–c). The first type of signal (advertisement call) was recorded in ten individuals (mean 7.8 calls per individual, mean snoutvent length = 26.69 ± 1.70 mm) and consisted of a single note similar to a “beep”, which lasted 87.8 ± 14.5 ms and whose dominant frequency was 3169.92 ± 141.33 Hz (N = 78) and the first harmonic has a peak frequency of 5159.34 ± 805.15 Hz (N = 61). Most of energy in the call (90%) was concentrated within 2601.64 ± 165.61 Hz and 3290.68 ± 122.88 Hz. The dominant frequency shows a slope of 12.90 ± 2.73 Hz/s and a mean modulation index of 1.64 ± 1.15. FigurE 1. Male of Eleutherodactylus rubrimaculatus (a). Advertisement call (b) and a second type of call (c) of E. rubrimaculatus recorded at Escuintla municipality in Chiapas state, Mexico. Air temperature at time of recording = 21.8°C, mean snout-vent length = 26.69 ± 1.70 mm. Upper graphs: spectrograms. Lower graphs: oscillograms. The second type of signal was heard less frequently throughout the field samplings than the advertisement call. We observed a couple in amplexus, likely male and female based on size differences (see Supplementary Video). After a few minutes, the amplexus was broke-off with no egg deposition and both individuals emitted this second call. This signal was recorded for a total of three individuals (mean 8.5 calls per individual) and is composed by 3 to 5 short notes (mean 4.1 notes). Each note lasted on average 29.5 ± 12.1 ms (47.0 ± 13.3 ms for the last tone and 24.1 ± 0.3 ms for the remaining) and was followed by short silent intervals of 1.3 ± 0.4 ms on average; the mean call duration was 167.8 ± 21.72 ms and the mean dominant frequency was 2339.37 ± 435.24 Hz (N = 25), the first harmonic had a peak frequency of 3974.77 ± 350.79 Hz (N = 17). As observed in the spectrogram (Fig. 1c) the second call, shows a higher complexity in comparison with the first one, it shows a lower slope for the dominant frequency of 4.73 ± 3.32 Hz/s and it has a higher modulation index (8.76 ± 5.91, N = 25). This study comprises one of the few call descriptions with temporal and spectral features measured for continental Eleutherodactylus. Few Eleutherodactylus species have had their advertisement call described and most are restricted to the Caribbean island of Hispaniola (Galvis et al. 2016). Among the Mexican species with call description are E. marnockii, E. pipilans, and E. nitidus (Fouquette 1960), E. grandis (Serrano 2016), and E. cystignathoides (Serrano & Penna 2018). Calls of E. grunwaldi and E. wixarika were described in the species description (Reyes-Velasco et al. 2015) and recently Grünwald et al. (2018) gave a brief description of the call of six new species. When comparing the parameters of the calls (Table 1), we found a clear differentiation for E. rubrimaculatus calls by the dominant frequency and call duration in both call-types regards previously described ones. Although female calling is very rare in anurans (Goyes Vallejos et al. 2019), female reproductive vocalizations have been reported before in various Eleutherodactylus species such as E. angustidigitorum, E. nitidus, E. guanahacabibes and E. cystignathoides (Serrano & Penna 2018). Reciprocal calling by female has been reported in some continental and Caribbean species (E. angustidigitorum, E. podiciferus and E. coqui; Reyes-Velasco et al. 2015). In the case of the second 590 · Zootaxa 4732 (4) © 2020 Magnolia Press MENDOZA-HENAO ET AL. call of E. rubrimaculatus we could not verify the sex of the individuals recorded so further evidence must be obtained to verify that female calls on this species. Therefore, our work not only provides new information of the acoustic communication signals for taxonomy purposes but also opens a new opportunity to understand the complexity of reproductive and calling behavior on Neotropical anurans. TAblE 1. Comparison of calls described among Mexican Eleutherodactylus species (Mean ± SD). * = Dominant frequency estimated as the mean value based on range frequency reported. (♂ = male, ♀ = female). NA = Not available. Species E. rubrimaculatus ♂ E. rubrimaculatus ♂ ♀ (?) E. grunwaldi ♂ E. wixarika ♂ E. grandis ♂ E. colimotl ♂ E. erendirae ♂ E. floresvillelai ♂ E. jaliscoensis ♂ E. manantlanensis ♂ E. nietoi ♂ E. cystignathoides ♂ E. cystignathoides ♀ Dominant frequency (Hz) 3169.9 ± 141.3 2339.3 ± 435.2 2130 ± 0.02 2750 ± 0.04 2238.8 ± 1.6 3058.7 ± 210.3* 3581.2 ± 129.0* 3700* 2625 2665* 3610* 3880.2 ± 270.1 3996.3 ± 343.0 Call length (ms) Call rate (/m) 87.8 ± 14.5 167.8 ± 21.7 70 ± 10 130 ± 40 169.7 ± 7.3 105.0 ± 28.3 166.0 ± 83.4 210 166 220 257 317.5 ± 196.8 383 ± 79 2.91 ± 3.3 12.4 ± 9.1 6.13 ± 1.3 6.13 ± 2.7 3.9 NA NA NA NA NA NA 6.01 ± 3.6 3.82 ± 2.3 Source This study This study Reyes-Velasco et al. 2015 Reyes-Velasco et al. 2015 Serrano 2009 Grünwald et al. 2018 Grünwald et al. 2018 Grünwald et al. 2018 Grünwald et al. 2018 Grünwald et al. 2018 Grünwald et al. 2018 Serrano & Penna 2018 Serrano & Penna 2018 Acknowledgments We thank Angel Fernando Soto, Mirna Garcia-Castillo and Gerardo Alexis Hilerio-Gutierrez for their support in the field. 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