Bioacoustics of Ewartia adusta

Measurements . Range and mean (in mm) for 10 males , 10 females (includes smallest and largest specimens). Length of body (including head): male 14.4–18.0 (16.0); female (including ovipositor) 15.0–19.4 (17.7). Length of forewing : male 17.0–21.2 (18.9); female 18.8–24.3 (20.8). Width of head (including eyes): male 4.8–6.0 (5.2); female 5.1–6.1 (5.7). Width of pronotum (across lateral angles): male 5.0–6.1 (5.4); female 5.2–6.4 (5.9). Distinguishing features . Distinguished from all other species by having, in combination, forewing veins M and CuA fused for a length equal to at least the length of the basal cell, the forewings infuscated on crossveins r and r-m, and in having dominating black sigilla on the mesonotum with the black extending to the cruciform elevation. The male genitalia are closely similar to other Ewartia species and not particularly useful for separating closely allied species. Song ( Figs 41a–f ). Recordings were examined from the WA.LAV, WA.MRS, WA.NSF, WA.PBB, WA.SHY, WA.VIC, NT.LJB, and NT.ULH paratype locations, along with additional sites in Western Australia and Northern Territory . Ewartia males exhibit two calling song modes, a complex song and a simple song (see Popple 2017b ). Each mode can be continued for extended periods. Two song modes are also produced in Ewartia adusta sp. n. Both vary considerably in form within a single male’s song. Most of the recordings obtained here contained only the simple song mode. Based on the limited available sample, the main section of the complex song ( Figs 41a–c ) consists of a phrase lasting approximately 1.5–3 s that contains approximately 2–5 repeated echemes and concludes with a modified echeme that ends with a short isolated syllable that probably serves as a cue for a receptive female to reply (the “accentuated” syllable of Popple 2017b ). Each echeme other than the final one consists of a long (0.2– 0.5 s ) syllable followed by a series of short syllables that gradually decrease and then increase in repetition rate (from about 25–50 syllables/s). Near the end of these echemes, the short syllables begin to coalesce and may form an intermediate-length syllable. In the final echeme, the short syllables do not increase in rate at the end, and instead the isolated cueing syllable is produced. The final echeme is sometimes considerably shortened, and the whole phrase can be preceded by a series of short syllables that vary in rate. The cueing syllable is 0.04– 0.05 s in duration and is preceded and followed by silent gaps of about 0.15 and 0.1 s , respectively. The simple song mode ( Figs 41d–f ) consists of long syllables of about 0.15– 0.2 s duration (or, in some cases, macrosyllables formed by coalesced syllables) repeated at about 2.5–3 per s. Often these syllables become broken to varying degrees into composite syllable pairs or threes. The underlying pulse rate of both song modes varies from around 500–1250/s and is difficult to discern apparently due to shifting relationships of the timbal contractions. Both modes have sound energy focused in the range 11.5–18.5 kHz, with a peak of about 14.5 kHz. There is little frequency modulation. Certain other Ewartia species have songs that are similar to that of E. adusta sp. n. , but none exhibit a pattern in which long syllables are normally following by steadily decreasing-rate short syllables in the complex song ( Popple 2017b ). Ewartia etesia and E. thamna , for example, have the pattern reversed, with short syllables increasing in rate towards a final long syllable that may precede the song cue.