Phaesticus Uvarov, 1940

Zha, Ling-Sheng, Skejo, Josip, Mao, Ben-Yong & Ding, Jian-Hua, 2021, Taxonomic revision of Phaesticus Uvarov and synonymy with Flatocerus Liang & Zheng syn. nov. (Orthoptera: Tetrigidae), Zootaxa 4965 (3), pp. 501-514 : 502-504

Genus Phaesticus Uvarov, 1940

( Phaestus Bolívar, 1887 ; Lamprauges Blackith, 1992 )

= Flatocerus Liang & Zheng, 1984 syn. nov.

Type species: Phaesticus mellerborgi ( Stål, 1855)

Redescription of generic characteristics

General appearance. Body size small, surface smooth and without humps or wrinkles. Head. Vertex and occiput clearly separated by a ridge (posterior margin of fossulae); vertex extremely shortened, sloping forwards, only restricted between anterior and posterior margins of fossulae; anterior margin narrowest, only reaching the middle of the inner margins of eyes in dorsal view; medial carina and frontal costa not quite developed ( P. mellerborgi and P. moniliantennatus ) or indistinct ( P. hainanensis comb. nov.), lateral carinae indistinct, medial carina extending to occiput; in lateral view, face obtusely angled forwards, facial carinae between antennal grooves strongly arcuate to obtusely angled, vertex and the upper part of face (above antennal sockets) nearly at the same slope ( P. hainanensis comb. nov.) or form a broadly obtuse angle ( P. mellerborgi and P. moniliantennatus ); longitudinal furrow deep, equal to or narrower than the diameter of an antennal scapus. Antennae inserted slightly below the lower margin of eyes (upper margin of antennal sockets and lower margin of eyes nearly at the same level), 13-segmented (or 14- segmented, because the 3 rd segment is usually separated into two short segments), the 11 th and parts of its adjacent segments generally milky white to yellow; subapical segments (generally from 7 th (8 th) to 10 th) considerably broadened and flattened, ovate ( P. mellerborgi ) or long elliptical ( P. moniliantennatus and P. hainanensis comb. nov.). Eyes approximately as high as the top of vertex and not higher than the anterior margin of pronotum, in frontal view with nearly straight inner margins which are slightly contracted upwards. Superior ocelli situated at lower 1/3–1/4 of the inner margins of eyes. Pronotum. Anterior margin projected more or less forwards, broadly arcuate or obtusely angled in dorsal view; median carina distinct and entire, humeral angles broadly arcuate; posterior angel of lateral lobe extending obliquely, downwards and backwards, apex truncated; ventral sinus and tegminal sinus present. Wings. Fore and hind wings normal ( Zha et al., 2016, 2020); hind wings elongated or shortened within the same species, varying with the length of hind pronotal process (detailed in discussion). Legs. Dorsal and ventral margins of fore and mid femora straight or nearly straight; the first segment of hind tarsus approximately as long as the third, apices of three pulvilli obtuse.

Justification of taxonomic placement

Phaesticus can easily be separated from other genera of the family Tetrigidae by the following characteristics: obtusely angled face in lateral view, extremely short vertex sloping forwards, indistinct lateral carinae of vertex, 13-segmented (not considering the separation of the 3 rd segment) antennae with considerably broadened subapical segments, smooth body surface without humps or wrinkles, developed fore and hind wings, directing downwards lateral pronotal lobes with truncated apices, and the first segment of hind tarsus approximately as long as the third. These typical characteristics are somewhat more similar to Metrodorinae and Tetriginae than to the other five subfamilies in Tetrigidae . Skejo (2017) commented its taxonomic placement in detail and speculated that it might belong to Metrodorinae or Tetriginae . We think it might be an independent branch close to Metrodorinae and Tetriginae . Future molecular phylogenetic evidences are needed to confirm its taxonomic placement.

Key to the species of the genus Phaesticus Uvarov, 1940

Fig. 1

1. Subapical antennal segments from eighth to tenth strongly broadened, ovate, and the widest segment about 1.7–2.4 times as long as it is wide. Distributed in Java, Sumatra, Kalimantan, Singapore, West Malaysia, Thailand, India (Assam, Mizoram), PR China (Yunnan)................................................................. P. mellerborgi ( Stål, 1855)

-. Subapical antennal segments from seventh to tenth moderately broadened, long elliptical, and the widest segment is about 3.6–4 times as long as wide.................................................................................. 2

2. Vertex wide, 1.5 times as wide as one eye; pronotum roof-like in front of the shoulders while slightly roof-like behind the shoulders, anterior margin broadly arcuate from dorsal view. Distributed in PR China (Hainan)........................................................................................... P. hainanensis ( Liang, 1988) comb. nov.

-. Vertex narrow, 0.9–1.3 times as wide as one eye; pronotum lamellate, anterior margin obtusely angled from dorsal view. Distributed in northern Vietnam, PR China (Guangxi, Guangdong, Guizhou, Fujian, Hunan).................................................................................................... P. moniliantennatus ( Günther, 1940)

Figures

FIGURE 1. Distribution of the genus Phaesticus and its three species.