Segestidea novaeguineae (Brancski, 1897)

Segestidea novaeguineae (Brancski, 1897) View in CoL

( Figs 33 View FIGURE 33 , 34 View FIGURE 34 )

Specimens studied. (1 male) Papua New Guinea, McAdam Nat. Park , Bulolo Gorge, 28 viii 1981, Coll. G.K.Morris.

Systematics. The male fits perfectly the redescription (F. Willemse 1977, 1979).

Comments. Common name palm katydid. Several Sexava spp. are pests of Oil Palm ( Page 2005).

Distribution. The locality of this species is covered by the distribution as mapped in F. Willemse (1977, 1979).

Stridulation. Sustained over many seconds, the buzzes of the single recorded male ( Fig. 34A View FIGURE 34 ) time resolved to regularly repeated wave trains of about 60 ms duration ( Fig. 34B View FIGURE 34 ) with a regular period of a quarter second (0.25 s). The trains are characterized by a highly erratic amplitude envelope ( Fig. 34B View FIGURE 34 ). Spectrum frequencies formed one broad aggregate in the audio range ( Fig. 34D View FIGURE 34 ): for 10 averaged calls this aggregate centred on 10.0 kHz. Though the spectrum is markedly low Q, the waveform of the pulse is not a train of distinctly time-separated transients and at higher time resolution these are seen to be almost sinusoid ( Fig 34C View FIGURE 34 ); visible are distortions of the sine waves which might be the result of overloading the recording equipment or alternatively of a low sampling rate.

A related species Sexava femorata C. Willemse , exhibits mandibular stridulation as a protest sound.A restrained female moved her labrum to and fro, sliding it “vertically over the anterior surface of her mandibles” ( Lloyd & Gurney 1975). Working with a recorder (Uher 4000 Report L) limited to the audio frequency range these authors found sound spectral energy for this defensive strigin near 3.5 kHz.