Bioacoustics of Ewartia lapidosa

Distribution and habitat . Ewartia lapidosa n. sp. occurs in the subcoastal and inland semi-arid areas of Queensland and New South Wales from near Georgetown and the White Mountains near Pentland in the north, south-east to Moogerah Dam and south to Mount Hope, Bumberry, Capertee and Singleton ( Fig. 15 ). Populations are found almost exclusively in association with wattle species that grow on hard, stony ground. The cicadas are found where wattles ( Acacia spp.) occur both as a monoculture scrub and as a middle canopy or shrub layer component of open forest. Adults occur from late September to March. This species is typically found on wattles ( Acacia spp.), growing in stony and sandy soils, including soils derived from sandstone. In New South Wales , it is typically found on Acacia cheelii , and has also been collected from A. doratoxylon at Mount Hope. In central and southern central Queensland , it is often found in association with Lancewood ( Acacia shirleyi ), but has also been found on A. julifera and A. burrowii . Around Charleville, St George and Morven, adults occur in association with Mulga ( Acacia aneura ). North of Miles, it is typically found on Acacia crassa . At Moogerah Dam, specimens were observed calling on Acacia blakei . Adults occur between late September and March. Calling song . The complex calling song mode of E. lapidosa n. sp. ( Figs 16–20 ) contains repeated subphrases of highly variable duration (mainly between 1.1 and 15.6 s ; all statistics n = 107 recordings). The opening section of each subphrase varies; however these often contain a regular pattern of macrosyllables (each 2–5 syllables, 0.021– 0.068 s duration) separated by a set of 1–5 discrete syllables (each 9–11 ms duration, gaps 0.034– 0.072 s duration). Alternatively, this section may contain a long syllable sequence (1.016– 8.337 s duration, with intersyllable gaps of 0.041– 0.115 s duration), or there may be a combination of macrosyllables separated by syllables (as described above) and a syllable sequence. More rarely, the opening section may become dominated by long sets of macrosyllables. This last pattern typically indicates a transition between the complex and simple calling song modes. The opening section sometimes concludes with 1–2 longer duration macrosyllables (each comprising 5–8 syllables, 0.061– 0.095 s ), although it may also end abruptly. It is then followed by either a single echeme (0.149– 0.824 s duration) or a series of 2–6 echemes of variable duration (each between 0.180 and 0.658 s ), each punctuated by either a single syllable or syllable sequences of variable duration (each between 0.109 and 0.452 s , and containing successively decreasing intersyllable gaps of 0.008– 0.035 s duration), which denotes the climax. In some cases, a final syllable sequence then ensues (0.190– 2.801 s duration, with intersyllable gaps of 0.010– 0.081 s duration). At the end of some subphrases this is followed by an accentuation, which typically comprises 1–3 (typically 2) macrosyllables (each containing 2–5 syllables), each separated by 1–5 syllables (with intersyllable gaps of 0.031– 0.106 s duration) or an uninterrupted gap (0.142– 0.326 s ), and followed by a final gap (0.065– 0.197 s duration). This calling song mode is typically produced at intervals throughout the day and interchanges with the simple calling song mode. The simple calling song mode of this species ( Fig. 21 ) contains monotonously repeated short echemes or macrosyllables (0.060– 0.166 s duration), each separated by a brief gap (0.044– 0.128 s duration). Sometimes the echemes or macrosyllables become separated by a single discrete syllable, which is typically indicative of a transition between the simple and complex calling song modes. The simple calling song mode predominates at dusk, but is also produced during the day. The presentation of the frequency spectra does not change between song modes. In each mode the calling song typically has a highest amplitude frequency plateau between 10.0 and 15.5 kHz, with a dominant frequency between 11.2 and 13.8 kHz (mean=12.4, n =54; e.g. Fig. 7 C, D). Ewartia lapidosa n. sp. exhibits some geographical variation in the structure of the complex calling song mode across geographical space, specifically in subphrase duration ( Figs 22 , 23 ). Notably, this attribute is quite consistent across its distribution in New South Wales . However, it is far more variable in Queensland , with individuals tending to produce more drawn-out subphrases, particularly in central and northern areas and shorter subphrases across the south ( Fig. 22 ). At Possum Park and at a site within Gurulmundi State Forest, subphrase durations appear to be bimodal, with the different durations associated with calling males that occur in parapatry in different groves of wattles at each of these locations (albeit with limited recording data; Figs 22 , 23 ). The most extreme example is in a series of three recordings made in the Nebo district of central Queensland by K. Hill and D. Marshall ( Fig. 23 ). Field observations suggest that production of the longer duration subphrases may be linked with occurrence in taller species of wattle ( Acacia spp.), but this is speculative and has never been investigation in detail. This situation could potentially indicate the presence of a complex of cryptic species within E. lapidosa n. sp. ; however further study would be required to explore the consequences of this song variation.