Spotted males, uniform females and the lowest chromosome number in Tettigoniids recorded: Review of the genus Gonatoxia Karsch (Orthoptera, Phaneropterinae)

The genus Gonatoxia Karsch, which was synonymized with Dapanera Karsch by Massa (2015), is re-established. Data on habitat, biology, ecology, the acoustics and on chromosomes are provided as well as a key to the species. The male of G. immaculata Karsch and the female of G. maculata Karsch are described. G. furcata sp. n. from the Udzungwa Mountains of Tanzania and G. helleri sp. n. inhabiting coastal and lowland wet forest are newly described. All species have calling songs consisting of very short, resonant syllables, produced in species specific intervals, and with peak carrier frequencies between 13 and 24 kHz. In respect to chromosome numbers Gonatoxia species showed extreme differences (from 29 to 7) suggesting rapid evolutionary changes. G. helleri sp. n. so far is the tettigoniid species with the lowest number of chromosomes at present. Gonatoxia species may be used as bioindicators, their presence suggesting valuable habitats that are vanishing rapidly in East Africa.