Bioacoustics of Xenogryllus mozambicus

Description. Species of average size ( Fig. 2 A–D), coloration light brown little contrasted. Eyes little prominent laterally ( Fig. 3K ), higher than long, occupying almost half of head height in lateral view. Face globular in lateral view ( Fig. 3L ), with typical whitish mask underlined by a black line below eyes and on mandibles. Pronotum dorsal disc strongly carinated laterally, coloration light brown, with a median dark brown band, not extended laterally near anterior margin; lateral lobes almost homogeneously dark brown. First article of antennae dark brown. Male. FWs very wide, longer than abdomen; dark coloration anterior to 1A including angle of 1A ( Fig. 5F ). Stridulatory file with 505 teeth (n=1) on transverse part of 1A. FW venation as in X. eneopteroides , mirror wider and apical field longer, forming a long triangle including 5–6 (n=8) cell alignments. Male genitalia ( Fig. 7 J–K): Similar to X. eneopteroides , except longer pseudepiphallic lophi ( Fig 8F ); transverse carina on ventral face of lophi present but weak. Female ( Fig. 2 C–D) FW dorsal field elongate, with 8–9 longitudinal veins (m = 9, n = 6). Subgenital plate with a shallow apical indentation ( Fig. 9D ). Ovipositor short, about 0.6 times FIII length. Female genitalia: Copulatory papilla ( Fig. 11 H–J) as in X. eneopteroides , conical and narrow, well-sclerotized except base and apex. Life history traits. X. mozambicus lives in areas of wet savannah ( Fig. 15 ) or on the edge ponds and lakes. Individuals of both sexes are found only at night in herbaceous vegetation, and males sing at night from the vegetation ( ca. 30–80 cm high). Toms (1984) demonstrated that this species has directional calls and turs while calling, giving rise to changes in sound intensity. Calling song ( Figs 12C , 16 ). At 21.5 °C, males of X. mozambicus emit almost continuously long bouts of highly musical calling songs. After a warming phase, call bouts are made of successions of echemes of 23 ± 2 syllables, barely separated from each other (echeme duration = 3.13 ± 0.29 s ; echeme period 3.21 ± 0.30 s , echeme duty cycle = 97.6 %), with a regular amplitude profile, except for the last syllable, which is more intense. Within echemes, syllables are initially organized in 4 ± 1 doublets, which are followed by a series of similar syllables. Syllables are very long (syllable duration = 126 ± 5 ms), with a relatively short syllable period of 137 ± 8 ms (syllable duty cycle = 92%). All syllables are characterized by a large amplitude modulation: in initial doublets within echemes, the first syllables are less intense than the second ones and they start with a lower amplitude than their end (initial amplitude ending amplitude); the rest of the syllables have a higher starting amplitude, except for the last syllable of each echeme, which has a higher ending amplitude. The frequency spectrum shows a pure-tone dominant frequency at 3.3 ± 0.01 kHz, followed by a rich harmonic content including three powerful harmonics at ca. 6.6, 9.9, 13.2 kHz, especially visible in ending syllables. Measurements. See Table 7 . Taxonomic discussion. The specimens observed by Toms (1984) and identified Xenogryllus eniopteroides (wrong spelling for X. eneopteroides ) from Zululand (Mtunzini and Eastern Transvaal (Clanor)), South Africa , belong to X. mozambicus n. sp. according to one male specimen observed from the series of Toms (NHMUK 010926568).