The breeding biologies of three species of treefrogs with hyperextended vocal repertoires (Gracixalus; Anura: Rhacophoridae)

Abstract

Gracixalus gracilipes, G. quangi, and G. supercornutus are small, morphologically and molecularly similar treefrogs with green blood from Vietnam, Laos and southern China. The breeding biologies, eggs, embryos and larvae of these three species are poorly known, and the male advertisement call of only G. quangi is known; this species has a hyperextended vocal repertoire. We provide new information on the breeding habitats, eggs, embryos and tadpoles of these three species and describe the calls of G. gracilipes and G. supercornutus. All three species deposit egg clumps on leaves overhanging shallow pools and puddles in forests. Like G. quangi, the calls of G. gracilipes and G. supercornutus are non-stereotypical, with individual calls highly variable in structure, duration, amplitude and frequency. Both calls are frequency modulated and have a dominant frequency of 4.1-4.7 kHz and many harmonics. The functional significance of these variations is unknown, and it is not known how common hyperextended call repertoires are within the genus.

A new species of Gracixalus (Anura, Rhacophoridae) from Yunnan, China

“…The obtained alignment of 16S rRNA sequences is 543 bp in length after cutting off both ragged sides. The newly collected samples from Bada, Xuelin, Fudong, Fazhanhe, and Lvchun of Yunnan, China form a distinct lineage together with samples from Houapan of Laos (KUHE 32453), Nghe An (AMS R173454) and Lao Cai (VNMN 4355, 4357, 4371) of Vietnam, and Jinping of Yunnan (KIZ 060821126) that were sequenced by previous studies (Yu et al 2008, Rowley et al 2011, Matsui et al 2015, Matsui et al 2017) (Figs 2, 3). Both Bayesian inference and Maximum likelihood analyses recovered this lineage as the sister to the clade consisting of G.ananjevae and Gracixalus sp.…”

“…Comparative morphological data of other Gracixalus species were taken from their original descriptions or re-descriptions (Boulenger 1893, Hu et al 1981, Ye and Hu 1984, Matsui and Orlov 2004, Orlov et al 2004, Nguyen et al 2008, Rowley et al 2011, Mo et al 2013, Nguyen et al 2013, Rowley et al 2014, Matsui et al 2015, Matsui et al 2017, Zeng et al 2017, Chen et al 2018, Wang et al 2018).…”

“…The genus Gracixalus Delorme, Dubois, Grosjean & Ohler, 2005 is known from southern and southwestern China, Vietnam, Laos, Thailand, and Myanmar and contains 16 species including G.ananjevae (Matsui & Orlov, 2004), G.carinensis (Boulenger, 1893), G.gracilipes (Bourret, 1937), G.guangdongensis Wang, Zeng, Liu & Wang, 2018, G.jinggangensis Zeng, Zhao, Chen, Chen, Zhang & Wang, 2017, G.jinxiuensis (Hu, in Hu et al 1978), G.lumarius Rowley, Le, Dau, Hoang & Cao, 2014, G.medogensis (Ye & Hu, 1984), G.nonggangensis Mo, Zhang, Luo, Zhou & Chen, 2013, G.quangi , Rowley, Dau, Nguyen, Cao & Nguyen, 2011, G.quyeti (Nguyen, Hendrix, Bohme, Vu & Ziegler, 2008), G.sapaensis Matsui, Ohler, Eto & Nguyen, 2017, G.seesom Matsui, Khonsue, Panha & Eto, 2015, G.supercornutus (Orlov, Ho & Nguyen, 2004), G.tianlinensis Chen, Bei, Liao, Zhou & Mo, 2018, and G.waza Nguyen, Le, Pham, Nguyen, Bonkowski & Ziegler, 2013 (Frost 2018). Of the 16 members of Gracixalus , ten were discovered in last decade (Nguyen et al 2008, Rowley et al 2011, Mo et al 2013, Nguyen et al 2013, Rowley et al 2014, Matsui et al 2015, Matsui et al 2017, Zeng et al 2017, Chen et al 2018, Wang et al 2018), indicating that species diversity of Gracixalus was very poorly understood in the past. Moreover, recent phylogenetic analyses (Matsui et al 2017, Chen et al 2018) showed that there are still several unnamed distinct lineages in the group of G.jinxiuensis , indicating that species richness of Gracixalus remains underestimated.…”

“…During recent fieldworks in Yunnan, China, we collected some specimens of a small-sized tree frog, which morphologically can be assigned to the genus Gracixalus by the presence of intercalary cartilage between terminal and penultimate phalanges of digits, tips of digits enlarged to discs bearing circummarginal grooves, vomerine teeth absent, inner (first and second) and outer (third and fourth) fingers non-opposable, and an inversed Y-shaped dark brown marking on dorsum (Fei 1999, Rowley et al 2011, Chen et al 2018), but morphologically and genetically can be distinguished from all recognized species of genus Gracixalus . Thus, we describe these specimens as a new species of Gracixalus .…”

The use of bioacoustics in anuran taxonomy: theory, terminology, methods and recommendations for best practice

“…This statement appears paradoxical given the large body of literature dealing with such variation (reviewed in the following sections), but in the majority of cases, intraspecific call variation in anurans refers to relatively subtle differences in quantitative variables, and not to fundamental differences in call structure. As suggested by Vences & Wake (2007), it remains to be critically tested whether this might be due to circular reasoning -because frog populations with strongly divergent calls would be considered as distinct species by taxonomists, thereby eliminating instances of intraspecific variation (but see Amézquita et al 2009 andRowley et al 2015 for examples of substantial call variation among populations). One obvious hypothesis that requires thorough testing is that call variation within species might originate and increase more slowly than does morphological variation, and whether this difference is accentuated in species from open areas showing little phylogeographic structure (Rodríguez et al 2015a).…”