Bioacoustics of Typophyllum morrisi

Description. As in T. egregium the internal tympanal chamber walls are not expanded beyond the dorsal surface of the fore tibia, but are developed like the external ones. Also, the bases of the hind tibia are not expanded, placing this species like the preceding one into the first group according to Vignon (1925a) . Tegmen shapes ( Fig. 5 C) do not correspond sufficiently well to any described males or females. And in males there is a unique modification of the stridulatory area at the base of the left tegmen: the proximal end of the fairly bulky stridulatory vein is dorsally developed as a knob, and directly behind it is a second knob of about the same diameter and as isolated structure being a little bit more conspicuous. The speculum of the right tegmen seems to be fairly stiff and is translucent but not transparent ( Fig. 7 B). In females the tegmina are mostly emarginated in a characteristic fashion at the distal anal margin ( Figs. 6 A, 7D), and only rarely the margin is uniform ( Fig. 7 E). One distinctive trait is shared by both sexes: the hind tibia sports a little below the middle, on the dorsal internal edge, a rounded, often downward-directed and drop-shaped process, of about the same diameter as the tibia ( Fig. 5 B). The prosternum has no spines; mesosterum and metasternum are laterally pointed, but not terminating as distinct spines. Coloration. Little variation; various shades of brown; most individuals are dark brown ( Fig. 7 ). Measurementes. Tegmen length in males 13–16 mm and in females 25–28 mm , hind femora in males 12–13.5 mm and in females 18–20 mm , antennae in females at least 50 mm . Acoustic behaviour. The two males that were recorded produced calls consisting of 3–6 (mostly 4 or 5) pulses ( Fig. 19 C). One individual pulse lasts about 30 ms and they are repeated every 120–130 ms. A five-pulse call lasts 500 ms at 23°C. Mostly two or three calls were produced together, separated by intervals of 400–500 ms. The pulses consist of a sustained and almost pure sine wave. The spectrogram shows a very narrow peak at 20.5 kHz and a faint harmonic at 41 kHz. The males seem to call only sporadically and the unique and easily recognizable song was never heard in the natural habitat while listening with a bat detector at night. The two knobs on the dorsal portion of the left tegmen of males might serve to dampen vibration of this tegmen, which otherwise could cancel out by negative interference the sound radiated by the speculum of the right tegmen, in case both tegmina vibrate out of phase. For the above-mentioned Typophyllum sp. nr. trapeziforme ( Morris et al. 1989 ) are described trills of 47–132 pulses with a total duration of 2.5– 7.0 s . The principal carrier frequency is 23.2 kHz. The high duty cycle might be due to captivity (see above T. egregium ; extremely elevated calling activity compared to duty cycles of freshly caught males, and males in natural habitat, also occur in other Ecuadorian katydids—pers. obs.). However, the carrier frequency is slightly higher than described for T. morrisi . So it is currently uncertain whether the lowland population from the Ecuadorian Amazon is truly conspecific. Mating behaviour. In a cage with three females and one male, was once at night observed the male riding on a female, but this female was found moribund the next day and no copulation occurred.