Bioacoustics of Limnonectes beloncioi

Diagnosis and comparisons.— Limnonectes beloncioi is a medium-sized fanged frog, assigned to the genus Limnonectes (family Dicroglossidae ), on the basis of its prominent, sexually dimorphic odontoid processes characteristic of the genus among other osteological synapomorphies ( Inger, 1954 , 1966 ; Emerson and Berrigan, 1993 ). The new species can be distinguished from all other known congeners based on a combination of its single-pulse/note advertisement call (vs. dual-pulses/note in L. acanthi from Palawan Island faunal region and PAIC landmasses), its phylogenetic position (sister to L. acanthi from Palawan PAIC; Evans et al., 2003 ; Setiadi et al., 2011 ), and its geographic distribution on Mindoro and Semirara Islands (vs. Palawan PAIC); it is the only species of Limnonectes known to occur on Mindoro and Semirara Islands and associated small satellite islands and, therefore, has no sympatric congeners. The new species is morphologically similar to its closest relative, L. acanthi ; however, it may be distinguished from this allopatric congener by its male advertisement call. The note pulse substructure of L. beloncioi is singular (1 pulse per note vs. 2 pulses per note in L. acanthi ), and the new species has a slower note repetition rate (11.5–12.8 notes per second vs. 14.2–15.4 notes per second), and has a higher dominant frequency (2,067.2–2,799.3 Hz vs. 1,335.1–1,679.6 Hz in L. acanthi ). With the exception of the morphologically indistinguishable L. acanthi , the new species can be distinguished from all other Philippine species of Limnonectes ( L. diuatus , L. ferneri , L. leytensis , L. macrocephalus , L. magnus , L. micrixalus , L. palavanensis , L. parvus , L. visayanus , and L. woodworthi ) by a combination of body size, fang (odontoid) length, snout shape, relative lengths of the first and second finger, dorsal skin rugosity, restriction of white-tipped dermal asperities to the sacral region (not aggregated in radial clusters), the presence of irregular, elongate, discontinuous dorsolateral ridges (absence of a continuous dorsolateral fold), complete interdigital webbing of the foot, and the absence of a dark inverted ‘‘V’’-shaped mark on the dorsum. We provide morphological comparisons below, based on our data, in conjunction with or with consideration of the descriptions of Stejneger (1910) , Taylor (1923) , Inger (1954) , Brown and Alcala (1977) , and Siler et al. (2009) . Limnonectes beloncioi differs from L. diuatus and L. ferneri by its rounded snout in lateral aspect (vs. posteroventrally sloping), its Finger I> Finger II relative finger lengths (vs. approximately equivalent length), and by restriction of white-tipped dorsal asperities to dorsal sacral region, and not distributed in radial clusters (vs. asperities not posteriorly restricted in L. diuatus ; and densely distributed across entire of dorsum, and concentrated in radial sacral clusters in L. ferneri ); and the presence of irregular dorsolateral ridges (absent in L. diuatus and L. ferneri ); from L. leytensis , the new species can be distinguished by its larger adult body size (SVL range 54.2–83.1 vs. 25.8.2–34.0 mm in L. leytensis ), rounded snout (vs. snout moderately pointed in lateral aspect in L. leytensis ), Finger I> Finger II (equivalent length in L. leytensis ), complete webbing (webbing incomplete/reduced in L. leytensis ), and the absence of an inverted ‘‘V’’-shaped mark on the anterior dorsum (vs. present in L. leytensis ); from a large male specimen of L. macrocephalus (the species endemic to the Luzon PAIC landmasses of Luzon, Polillo, Catanduanes , and Marinduque ), the new species can be distinguished by the observation that it attains a considerably smaller maximal adult male body size (SVL range 54.2– 83.1 vs. 78.9–144.6 mm in L. macrocephalus ); the new species also possesses a fully exposed tympanum (vs. dorsal and/or posterior edge of tympanum hidden beneath overlapping supratympanic dermal ridge skin in L. macrocephalus ) and lacks sexual size dimorphism ( Table 2 ), whereas L. macrocephalus exhibits reverse sexual size dimorphism (males larger); from a large adult male specimen of L. magnus , the new species can similarly be distinguished by its smaller adult body size (SVL range 54.2–83.1 vs. 66.3–164.4 mm in L. magnus ), rugose middorsal skin texture (vs. smooth to shagreened in L. magnus ), fully exposed tympanum (vs. dorsal and/or posterior edge of tympanum hidden beneath overlapping supratympanic dermal ridge skin in L. magnus ), rounded snout (vs. pointed in L. magnus ), and by the absence of reverse sexual size dimorphism (present in L. magnus ); from L. parvus , L. micrixalus , and L. palavanensis , the new species can be distinguished by its larger adult body size (SVL 54.2–83.1 mm; vs. 24.2–35.5 in L. parvus ; 28.1–30.2 in L. micrixalus ; 30.0–37.6 in L. palavanensis ), rugose (vs. smooth) dorsal skin, Finger I> Finger II (equivalent length), the presence (vs. absence) of white-tipped sacral asperities and the presence of irregular, discontinuous dorsolateral ridges (vs. asperities absent, dorsolateral folds continuous), complete webbing (vs. reduced), and by the absence (vs. presence) of an inverted ‘‘V’’-shaped middorsal marking (vs. present); the new species is additionally distinguished from these species by the absence of sexual size dimorphism (vs. females larger in L. parvus , L. micrixalus , and L. palavanensis ); from L. visayanus , L. beloncioi is readily diagnosed by its rounded snout (vs. pointed in L. visayanus ), a tendency towards longer adult male fangs (2.6–5.6 vs. 1.8–3.0 mm in L. visayanus ), by the presence (vs. absence) of white-tipped sacral asperities; finally, the new species can be distinguished from L. woodworthi by its longer male fangs (2.6–5.6 vs. 1.3– 1.6 mm in L. woodworthi ), moderately rugose middorsal skin (vs. smooth in L. woodworthi ), rounded snout (vs. snout moderately pointed in L. woodworthi ), the presence (vs. absence) of white-tipped sacral asperities, and by the absence (vs. presence) of continuous dorsolateral folds.