Sigmaboilus, Fang, Yan, Zhang, Haichun, Wang, Bo & Zhang, Yutao, 2007

Fang, Yan, Zhang, Haichun, Wang, Bo & Zhang, Yutao, 2007, New taxa of Aboilinae (Insecta, Orthoptera, Prophalangopsidae) from the Middle Jurassic of Daohugou, Inner Mongolia, China, Zootaxa 1637, pp. 55-62 : 56

Genus Sigmaboilus gen. nov.

Type species. Sigmaboilus gorochovi sp. nov.; here designated.

Diagnosis. Tegmina medium-sized to large. Precostal area very broad (about 1/3 – 1/2 total width at the base) with numerous “radial veinlets” at base; C slightly sigmoidal, extremely long, and ending in anterior margin beyond first branch of RA; Sc long with numerous branches ending in stem C; “oblique veins” (crossveins between CuA2 and CuP) gently curved and regularly arranged; “handle vein” (a single cross vein crossing some of the nearest crossveins between the base of MP+CuA1 and CuA2) slightly curved, and almost parallel to the nearest crossvein between last branch of MP+CuA1 and CuA2; after meeting as MP+CuA1, MP and CuA1 united for a short but appreciable distance; CuP touching 1A at a point close to hind margin of tegmen, but keeping an appreciable distance from 2A.

Type horizon and locality. Middle Jurassic; Daohugou Village, Ningcheng County, Chifeng City, Inner Mongolia, China.

Etymology. The generic epithet is from Latin sigmoideus, in reference to the sigmoid stem C, and the genus Aboilus . Gender: masculine.

Composition. Three species, the type Sigmaboilus gorochovi sp. nov., S. sinensis sp. nov. and S. longus sp. nov..

Discussion. This genus is attributed to Aboilinae based on the following combination of character states: broad precostal area, well-developed longitudinal stem C, rather simple male stridulatory apparatus, and straight or almost straight proximal “oblique veins” in male tegmina.

The genus differs greatly from other genera within Aboilinae in the unusually long C in the tegmen (ending in anterior margin beyond the first branch of RA), otherwise it is similar to Aboilus Martynov, 1925 , Sunoprophalangopsis Hong, 1982 , and Utanaboilus Gorochov, 1990 . However, it can be distinguished from the three genera by its narrower and longer tegmen, with MP and CuA1 united for a short but appreciable distance after their meeting, and “handle vein” slightly curved. It further differs from Aboilus in “radial veinlets” numerous in precostal area, and stem CuA2 almost straight; from Sunoprophalangopsis in “handle vein” not crossing the nearest crossveins between MP+CuA1 and CuA2; and from Utanaboilus in most branches of Sc ending in stem C. Moreover, this genus is different from other genera of Aboilinae including Bacharaboilus Gorochov, 1988 , Apsataboilus Gorochov, 1990 , Tettaboilus Gorochov, 1988 and Prophalangopseides Sharov, 1968 in the following aspects: the tegminal shape, width of the area between R and MA, branching mode of MP+CuA1 and the relationship between “oblique veins”.