Bioacoustics of Kaloula discordia

Acoustic data. For a comparison of the male advertisement calls of Kaloula discordia sp. nov. with K. indochinensis sensu stricto , see Table 3 ; data for K. indochinensis are taken from Nguyen et al. (2022) . The power call parameters of Kaloula discordia sp. nov. and K. indochinensis are quite similar, with the dominant frequency of the call being the same in the two species (0.38 kHz, range 0.34–0.43 kHz vs. 0.38 kHz, range 0.30–0.45 kHz, respectively) (Table 3 ). At the same time, Kaloula discordia sp. nov. had a slightly shorter call duration (186.1 ms, range 144–214 ms) than K. indochinensis (215.6 ms, range 194–250 ms) and a significantly longer intercall interval: 1539.4 ms (range 851–8954 ms) in Kaloula discordia sp. nov. vs. 789.3 ms (range 481–1627 ms) in K. indochinensis . These differences have to be taken cautiously as the records of calling of the two species were taken with different ambient temperatures (20.5 ° C for K. indochinensis and 24.0 ° C for the new species), which also could contribute to the observed differences in call parameters between the two species. Nguyen et al. (2022) did not calculate the number of pulses per call in K. indochinensis and noted the presence of one pulse per call in this species ( Nguyen et al. 2022 : Table 2 ), while we recorded 11–13 pulses per call in Kaloula discordia sp. nov. These differences actually result from the different terminology used by Nguyen et al. (2022) and our study, as the waveform oscillograms in Nguyen et al. (2022) clearly show the presence of several pulses in each call.

Distribution and natural history. Kaloula discordia sp. nov. is currently reliably known from Dong Nai , Lam Dong , Tay Ninh , and Binh Phuoc provinces of Southern Vietnam and was also reported from the adjacent Mondulkiri Province of eastern Cambodia ; the known distribution of the new species is shown in Fig. 5 , and the locality information is detailed in Appendix 1 . The single Cambodian record of the new species from Phnom Prich Wildlife Sanctuary in Mondulkiri Province , originally reported as K. indochinensis by Chan et al. (2013) and Holden (2023) , can be confidently assigned to Kaloula discordia sp. nov. based on the external morphology and coloration of the recorded specimen and the geographic proximity of the locality to the population of Kaloula discordia sp. nov. in Binh Phuoc Province of southern Vietnam . The new species was recorded mostly from relatively low elevations of ca. 70–300 m a. s. l.; in Bao Loc forestry of Lam Dong Province , the new species was recorded at elevations up to 550 m a. s. l. Kaloula discordia sp. nov. is restricted to lowland and hilly, seasonally dry, semi-deciduous, and evergreen monsoon forests of southern Vietnam (see Vassilieva et al. 2016 ). Male frogs were recorded calling from small temporary pools and flooded areas from May to November (Fig. 7 A, B ); the peak of the breeding season coincides with heavy rains in June – August. The new species is semi-fossorial and quite elusive and is usually active only after periods of heavy rains; frogs are aestivating during dry periods in leaf litter, underground borrows, or tree hollows ( Vassilieva et al. 2016 ; Holden 2023 ). Diet consists of ants and beetles ( Vassilieva et al. 2016 ); the new species is a good climber; males can call when perching a few meters above ground level ( Holden 2023 ). The actual distribution of K. discordia sp. nov. is still insufficiently known, but we suppose that this species is likely to occur in those provinces of southern Vietnam where forests similar in composition are still preserved, including Dak Nong , Binh Duong , Binh Thuan , and Ba Ria-Vung Tau provinces. Syntopic species of amphibians included Microhyla butleri Boulenger, 1900 ; M. heymonsi Vogt, 1911 ; M. mukhlesuri ; Kaloula pulchra ; Fejervarya limnocharis (Gravenhorst, 1829) ; Occidozyga martensii ; Polypedates megacephalus Hallowell, 1861 ; and Rhacophorus annamensis Smith, 1924 .