Ornebius pullus Ingrisch, 2006

(Figs 1B, 4, 5)

Ornebius pullus Ingrisch, 2006: 157

Ornebius pullus — He et al. 2021: 88 [assigning to species group Ornebius (flori) Ingrisch, 1998]; Tan et al. 2021: 416 [notes on new locality and variations with Singapore specimens]; Tan et al. under review [calling songs from Singapore]

Ornebius cf. pullus — Tan 2012: 34; Tan & Ingrisch 2013: 25; Tan 2017: 55; Tan 2019: 335

Specimens examined. EAST MALAYSIA • 1♂; Sabah State, Tabin Wildlife Reserve; N5.19496, E118.50326, 117.1± 10.3 m.a.s.l.; 15 May 2022, 22h17; on the branch of a small tree; coll. M.K. Tan, T. Robillard & R. Japir; SBH.22.95 (FRC)

Remarks. The specimen collected from Sabah exhibits some differences with O. pullus collected from Belait (Brunei Darussalam) and Singapore: legs with more whitish marmoration, supra-anal plate whitish when alive. However, we could not identify clear-cut differences in the genitalia, including both the sclerotized median valve and the membranous lateral valves between the specimen from Sabah and those from Brunei Darussalam (Fig. 5). As Tan et al. (2021) have also suggested that there might be a polymorphic species and that more evidence was needed (e.g., DNA or acoustics) to better understand the species boundaries. At the moment, the external morphology and genitalia morphology are not congruent between specimens from Brunei Darussalam, Singapore and Sabah; we also do not have acoustic data for the Brunei population; and no molecular data are available.

Furthermore, the specimen from Sabah also shares some similarities (but also with clear differences) in the external morphology of Ornebius minusculus (Chopard, 1929) from Sipura Island (Sumatra) (http://coldb.mnhn.fr/ catalognumber/mnhn/eo/ensif4531), although the genitalia for this species has not been examined. As such, without more specimens from Sabah to examine variations, we refrained from describing it as a new species, tentatively identified it as O. pullus and preferred to revise its taxonomy when the chance arises.

Distribution. Brunei Darussalam (Belait and Brunei-Muara Districts), East Malaysia (Sabah State) [new locality record], Singapore.

Type locality. BRUNEI DARUSSALAM, Brunei-Muara District, near bridge over river Sungai Lubang Barus on road coming from Tutong.

Calling song (1 ♂, in captivity, 31.5°C) (Fig. 4). The calling song generally consists of a sequence of syllables (= pulses), which can be highly variable in duration (2–14 s or 4–25 syllables). The average syllable duration is 37.5±5.0 ms (31.0–46.0 ms) and the average interval between consecutive syllables is 501.2±20.4 ms (469.3–538.4 ms). The dominant frequency is 7.97±0.13 kHz (7.78–8.16 kHz).

Compared to the calling song of Ornebius pullus from Singapore (see Tan et al., under review), the calling song of this specimen from Sabah has a similar call structure (i.e., the calls of both species are made up of a sequence of syllables). The biggest difference is in the interval between consecutive syllables being distinctly longer (501.2 ms vs. 400.0 ms) than that from Singapore. The syllable is only marginally longer in duration on average (37.5 ms vs. 32.4 ms) and the dominant frequency is not different (8.0 kHz vs. 8.1 kHz).