Bioacoustics of Typophyllum erosifolium

Description. The internal tympanal chamber walls are expanded, extending well beyond the dorsal surface of the fore tibia, placing this species in the third group according to Vignon (1925a) . Apart from the general shape of the sexually dimorphic tegmina ( Fig. 13 ) there are no really disctinctive characters. Of the six females found in the area, five have tegmina with uniform anal margin, whereas in one the distal portion is undulated. In males the anal margin is undulated to varying degrees, and there is a deep distal emargination of the costal margin which almost reaches the radial vein. In the male holotypes of T. curtum and T. mutilatum , the only remaining species in the third group, this emargination is fairly far separated from the radial vein (photos in OSF). In females the pronotum has two elongated tubercles at the anterior margin, each located about one forth of pronotum diameter from the lateral edge, and in the middle of the posterior margin there is sometimes a small, basally fused two-tipped process. The speculum of the right tegmen in males is fairly stiff, whitish, and barely translucent. The prosternum has no spines, the lateral tips of the mesosternm are developed as delicate spines (almost twice as long as distal width of maxillary palp), and the metasternum has more robust spines of about the same length. Coloration. Variable, light of dark brown, sometimes greenish or almost completely green ( Fig. 15 ). The dorsal surface of the middle tibiae can be white in the lower half. One female had small white tubercles on the tegmina ( Fig. 15 C), which became dark after death. Another female had extensive whitish spots ( Fig. 14 ). Especially the tegmina are distinguished by numerous tiny accessories that perfect the resemblance to a real decaying leaf, like transparent parts imitating holes, microscopic dark and whitish tubercles resembling small fungi, bright lichenous marks, or greenish parts as if there grew moss. Measurements. Tegmen length in males 15–19 mm and in females 28–36 mm , hind femora in males 12–13 mm and in females 15–17 mm (in T. peruvianum 21 mm according to the description and missing in the holotype , tegmina 32 mm ). Acoustic behaviour. This species calls unwearily, sometimes many minutes without interruption. The pulse length usually is about 55 ms (ranging from 50 to 70 ms depending on the individual) and the intervals between the pulses last alternately 160 and 400 ms at 19°C, or 230 and 670 ms at 16°C in the natural habitat. The frequency spectrogram shows a very narrow peak at 18–19 kHz and very small peaks of the harmonics at 37 kHz and 55–56 kHz ( Fig. 19 D). While individuals can be heard over fairly long distances using a bat detector, with the unaided human ear the song is perceivable over only 1–2 m in the forest to a few meters in a quiet room, reminding of some very tiny machine in need of lubrication. Calling begins with the short equatorial dusk and the males mostly sit rather low in the vegetation, apparently up to 3– 4 m . Within the range of this species in the well-investigated Reserva Biológica San Francisco, listening at night with a bat detector, very rarely more than one calling male was heard from a particular spot, and mostly none. This indicates a very low population density. At the sites Bombuscaro and Alto Nangaritza this species was never heard, despite extensive listening. Mating behaviour. One male (cbt001s05) was found at night riding laterally on the wings of a female (cbt001s04), the whole ensemble sitting on the flower of a species of Solanaceae . This indicates that this little walking leaf shares the curious piggyback-behaviour typical of the genus Typophyllum , described above for T. egregium .