Sphingonotus savignyi Saussure, 1884

Sphingonotus savignyi Saussure, 1884 View in CoL

Figs 1–15, 22.

MATERIAL. 1. Southern Kazakhstan, ca 30 km north of Almaty, environs of Kara-Oy village, pebble shore of the Kaskelen River , 43.5381° N, 76.8678° E, 22.VI.2024, signals of five males were recorded at 30–35 °C GoogleMaps .

2. Southern Kazakhstan, the rocky desert in the Charyn River Valley, ca 20 km north of Chundzha (=Shinzha), 43.7153° N, 79.4175° E, 24.VI.2024, signals of three males were recorded at 40–42 °C GoogleMaps .

SONGS. Songs of two types were recorded in males of S. savignyi .

The song of the first type is an echeme-sequence produced during a flight display and followed by a sequence of syllables produced by stridulatory movements of hind legs immediately after landing ( Figs 1–8). The flight display lasts for about 1.0– 1.5 s at a height of about 30–40 cm; during the flight the male produces 5–6 echemes including 3–8 (typically, 4–6) syllables each ( Figs 1–4). Syllable repetition period averages 19–22 ms, echeme repetition period varies from 150–180 up to 200–300 ms in males from both localities in spite of the air temperature differences during recordings ( Figs 5–6). Immediately after landing, the male usually, but not always, produces several pure-tone syllables with a carrier frequency of about 2.7–3.1 kHz; on the oscillograms at high speed it is visible that these syllables have a regular sine carrier ( Figs 7–8). To the human ear, this part of the song sounds like bird whistles or cricket pure-tone songs. Typically, the male produces 1–3 syllables separated by gaps of 50–100 ms and followed by an echeme lasting for 350–500 ms and having a syllable repetition period 19–22 ms at 30–35 °C and 15–17 ms at 40–42 °C ( Figs 3–4, 7). After that he produces single syllables separated by gaps from 200–300 up to 600–800 ms until he starts the next flight display. Usually, the male performs up to 5–7 flight displays with a period of about 5–6 s ( Figs 1–2).

The male produces the song of the second type by stridulation while sitting on the ground. This song is an echeme-sequence lasting up to 20–25 s ( Figs 9–11). Echeme repetition period normally averages 500–950 ms, but sometimes increases up to 1.5– 2.0 s and more. Each echeme consists of a succession of short click-like noise syllables following each other with a period of 15–21 ms in our recordings, one low-amplitude prolonged noise syllable sometimes almost indistinct on oscillograms, and one pure-tone syllable usually subdivided by amplitude modulations into several partially merged parts ( Figs 12–15). The number of click-like syllables per echeme varies in different males from 5–10 up to 25–30; their number apparently decrease when the male starts singing more regularly. The carrier frequency of the pure-tone syllable is 2.5–2.8 kHz i.e. almost the same as in pure-tone syllables in the song of the first type ( Figs 12–13). Sometimes, in the end of the song of the second type the male produces the same succession of pure-tone syllables as in the end of the song of the first type ( Figs 9, 12). Also, occasionally he starts flight displays during producing the song of the second type ( Fig. 11).

The song of the first type can be confidently classified as a calling song produced by single mature male for attracting conspecific female. The song of the second type was registered both in single male (at least no female was visible nearby) and in male courting female. Usually, courting male was sitting a few centimeters near female and singing. If the female attempted to escape, he moved after her, producing songs in the pauses between his movements, and, having overtaken her, sat in front of her head to head ( Fig. 22). No attempts of copulation were observed.

REMARKS. Some longitudinal veins of the hind wing in S. savignyi are slightly thickened [ Bey-Bienko, Mishchenko, 1951: 626], which is typical of species that produce signals during display flight.

The ability of this species to produce sounds in flight was noted by Shumakov [1963: 159]. A verbal description of its song, including the indication that the sounds produced on the ground resemble whistling, is given by Husemann & Hochkirch [2007] but no signal descriptions illustrated by oscillograms are known to us.