Account
What the sources say about this taxon, as written.
distribution · 
Plazi
Distribution. Philippines (Negros Island, Siquijor Island [new locality record]). Calling song ( 2♂ , 30.0°C) ( Fig. 11 ). The calling song consists of irregular sequences of echemes. Each sequence is made up of 4 to 13 echemes, average duration is 2.56± 0.80 s (0.93– 4.27 s ). Each echeme is made up of average 3±1 syllables (2–5 syllables). Average echeme duration is 0.10± 0.04 s (0.05– 0.18 s ), average silent interval between consecutive echemes is 0.20± 0.05 s (0.14– 0.36 s ) and average echeme period is 0.03± 0.08 s (0.21– 0.54 s ). Average syllable duration is 13.1±2.2 ms (9.6–17.3 ms), average silent interval between consecutive syllables is 24.3±2.4 ms (19.4–30.4 ms) and average syllable period is 37.4±3.3 ms (31.5–43.2 ms). The call spectrum is broadband and non-asymmetrical; two main energy ranges, between ca. 10 and 20 kHz and ca 40 kHz. The average peak frequency is 17.1±0.8 kHz (15.8–19.3 kHz). The calling song differs from that of morphologically similar Axylus philippinus (Hebard, 1922) from Luzon and Western Visayas (see Tan et al. , 2023 ) by its call structure (irregular sequences of echemes vs. continuous trill, respectively; typically tri-syllabic vs. di-syllabic echemes) and temporal call parameters. The frequency spectrum in both species has two energy peaks; but the peak frequency of A. negros is in the sonic range, whereas that of A. philippinus is in the ultrasonic range (17.1 vs. 34.7 kHz).
discussion · Plazi
Remarks. Our specimens from Siquijor Island appear darker in colouration in general, but the black patterns on the frons, gena and lateral lobes of pronotum are consistent with the holotype ( Figs 8 , 9 10A, 10B ). We also do not find observable differences in the male stridulatory area ( Fig. 10C ), tenth abdominal tergite, epiproct, cercus and subgenital plate ( Figs 10D, 10E ), as well as the titillators (although the apices of the lateral arms are faintly different) ( Fig. 10F ). The male cercus and titillators are also distinctly different from those of Axylus philippinus (Hebard, 1922) from Luzon and Western Visayas.