Altihoratosphaga

behaviour · bio.acousti.ca

All three recorded species produced songs containing the same two types of elements, A and B (Figs 3, 4). The simplest verse structure is found in A. hanangensis sp. nov., where almost invariably one A element and one B element were combined. These AB verses were repeated at intervals of 12.5 ± 3 s (N= 10; 18 °C, estimate). Only once was an isolated element A recorded. Element A consisted of seven groups of impulses, with the last group being by far the loudest, and element B consisted of five or six single impulses or impulse groups, with the first of each group being by far the loudest (Fig. 3). ... Probable mechanism of sound production As can be recognized from the description (see also Figs 3, 4), the song has a fairly complicated structure that cannot easily be related to any pattern of stridulatory movement. However, the stridulatory file and song have some similarity to that of Acrometopa species (Heller, 1988). In these species the first part of a verse is produced by stridulatory movements using the distal part of the file only, whereas the end of the verse is produced by contact of the scraper with the large, proximal teeth (Heller, 1988: fig. 21–2). Assuming a similar sound production mechanism, possibly element A of Altihoratosphaga is produced by a fixed pattern of several opening and closing movements using the distal part of the file only, whereas the B elements may result from scraper–file contacts in the proximal part. [In this way complete syllables would never be produced, or would only be produced once per verse; instead, what may be called dista-syllables (different types) and proxi-syllables (one type) are sounded.]

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morphology · bio.acousti.ca

In all of the four species studied in detail (A. montivaga, A. nou, A. hanangensis sp. nov., and A. nomima), the stridulatory file on the lower side of the left tegmen showed a similar structure (Fig. 2). In its proximal part it bears relatively large teeth, whereas they decrease slowly in size to the end of the file at the edge of the tegmen. In A. nomima both parts are connected by a more or less continuous transition in tooth size (Fig. 2D). In the other three species the teeth gradually become larger from the articulation towards the centre of the file. Distal of the middle the teeth become abruptly smaller, and then decrease slowly in size (Fig. 2A–C). A file structure with two distinct parts in three of the four known species of Altihoratosphaga is quite different from that observed in other species of the genus Horatosphaga(H. heteromorpha, Horatosphaga legg(Kirby, 1909), and H. parensis; K.-G. Heller, C. Hemp, unpubl. data). Differences in the number of teeth and their size, as can be seen in Figure 2, may indicate species-specific parameters, but cannot be evaluated at present because of insufficient data.

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