Meristogenys stigmachilus

Sheridan, Jennifer A., Grafe, Ulmar, Márquez, Rafael, Narins, Peter M., Vázquez-García, Pablo & Yambun, Paul, 2024, Call descriptions of two species of Meristogenys (Anura: Ranidae) from Sabah, Malaysia with novel notes on species morphology, Raffles Bulletin of Zoology 72, pp. 356-363 : 358-360

Meristogenys stigmachilus .

We recorded calls of six males on 5 March 2023 at Mahua. All males were calling on vegetation within 1.5 m of the ground, and within 3 m of the stream edge, and close to a paved path alongside the stream between the park entrance and the Mahua waterfall. Males started calling around dusk, and calling activity seemed to be strongest in the first three hours after dusk. There was no rain during recording hours. Other species active and calling in the same vicinity included Huia cavitympanum , Leptolalax pictus , Meristogenys orphnocnemis , and at least one Ansonia species. Recordings were between 3:07 and 9:23 min long, each with 1–30 calls at irregular intervals ( Table 1 ). Visual inspection and measurements of dominant frequency, call duration, and delta frequency showed wide variation in call parameters and exact shape of calls ( Fig. 2 ; supplementary material). For simplicity, we grouped calls into four broad types, but emphasise that three of the four groups contain variation in the exact call shape as well as in the dominant frequency, duration, and delta frequency. Type A: flat or slightly increasing, B: long slow decline, C: short rapid decline, and D: staccato. Due to the wide range of measured parameters within groups A–C, we report here the range of values observed rather than mean ± SE and provide data of each individual call in supplementary material. Type D (staccato) calls were much more consistent, with a dominant frequency of 3064.3 ± 63.9 (mean ± SE), consisting of 17.4 ± 3.3 pulses at a rate of 16.7 ± 0.3 pulses/sec.

Little has been published about this species beyond its initial description, and during repeated nocturnal surveys in 2022, the authors (JAS, PVG, and PY) noted that while existing records state that this species has fine dark spots or melanophores on the chest and throat ( Inger et al., 2017) (https://www.frogsofborneo.org/frogs/ranidae/meristogenys/ stigmachilus), these spots only appear during the day or after preservation, while during nocturnal observations the chest and throat are white. Additionally, males and females were previously reported to be 43–50 mm and 69–80 mm SVL, respectively, but our observations included males of 45–53 mm and females 82–84 mm SVL.

Figures

Fig. 2. Example calls of Meristogenys stigmachilus recorded at Mahua sub-station, Crocker Range National Park, Sabah, Malaysia, March 2023. A–D: call type A; E–H: call type B; I–L: call type C; M–O: call type D.