Platygavialidium Günther, 1938

Muhammad, Amira Aqilah, Tan, Ming Kai, Abdullah, Nurul Ashikin, Azirun, Mohammad Sofian, Bhaskar, Dhaneesh & Skejo, Josip, 2018, An annotated catalogue of the pygmy grasshoppers of the tribe Scelimenini Bolívar, 1887 (Orthoptera: Tetrigidae) with two new Scelimena species from the Malay Peninsula and Sumatra, Zootaxa 4485 (1), pp. 1-70 : 40

Genus Platygavialidium Günther, 1938

Platygavialidium: Günther 1938a , Bey-Bienko & Mistshenko 1951, Kevan 1966, Blackith 1992, Ichikawa 1994, Zheng 1994, Yin et al. 1996, Otte 1997, Liang & Zheng 1998, Deng 2016, Skejo & Bertner 2017.

Type species: Eugavialidium formosanum Tinkhkam, 1936

Composition and distribution. Five species distributed in the Philippines ( P. dentifer , P. kraussi , P. productum comb. nov.), PR China ( P. sinicum ), R China [= Taiwan] ( P. formosanum )

Notes. When the genus was established (Günther, 1938), it included species without complex ventrolateral projection (as opposed to saw-like ventrolateral spines in Gavialidium ). However, this character alone cannot be useful. Problematic taxonomy resulted in some Platygavialidium species being assigned to Gavialidium , including Gavialidium productum ( Walker, 1871) and G. philippinum ( Bolívar, 1887) from the Philippines. Two mentioned species lack dentate carinae, wrinkled dorsum, and fastigial horns. Diagnostic characters of the genus Platygavialidium are wide shoulders (metalateral tubercles, not strongly triangularly projected as in Paragavialidium nor as oblique as in Gavialidium ), lack of fastigial horn, wide vertex, strong ventrolateral projections, low pronotal projections (so pronotum is almost flat) and lack of large frontomedial projection. Species from the Philippines are very related and could all be synonymous. Platygavialidium formosanum ( Tinkham, 1936) from Taiwan is the type species of the genus. Platygavialidium nodiferum ( Walker, 1871) has much wider humeral angles projected as triangular plates and is not regarded member of this genus, but of Paragavialidium . Its morphology and distribution fit those of the Paragavialidium and thus P. nodiferum comb. nov. is proposed. The true taxonomic position of P. sinicum Günther, 1939 from Fujian, PR China remains unclear. Species other than the type species ( P. formosanum ) have lateral ocelli and the antennal grooves positioned lower than the type species. Four species from the Philippines that are closely related do not have exact distribution data, but we only know they inhabit the Philippines. Taiwan and Chinese species are less related to this group than the species within the group are related.