Sinaktassia, Lin, Qi-Bin, Nel, André & Huang, Di-Ying, 2010

Lin, Qi-Bin, Nel, André & Huang, Di-Ying, 2010, Sinaktassia tangi, a new Chinese Mesozoic genus and species of Aktassiidae (Odonata: Petaluroidea), Zootaxa 2359, pp. 61-64 : 61-62

Genus Sinaktassia gen. nov.

Type species. Sinaktassia tangi sp. nov.

Etymology. A combination of the Latin name ‘Sinica’ for China and the name of the closely related genus Aktassia . Gender feminine.

Diagnosis. Forewing characters only; hind wing unknown. Wing falcate, slender, and longer than 80 mm; postnodal space very narrow, with many cells distal of Pt; Pt elongate; pterostigmal brace present and shifted slightly basal to Pt; IR1 basally strongly zigzagged, long; only one row of cells between RA and RP 1 at level of Pt; space between RP 1 and RP 2 greatly expanded, with more than 8-9 rows of cells; PsA hypertrophied; subdiscoidal triangle widened, T transverse; subdiscoidal triangle divided by cross-veins; more than two rows of cells in basal part of postdiscoidal area between level of distal angle of T and level of midfork; groups of cells and secondary veins in areas between main veins; Bqs-area (‘bridge-space’) narrowed; distal side of T not angulated; only three rows of cells in postdiscoidal area just distal of T; no convex intercalary vein in postdiscoidal space; area between RP 3/4 and MA widened near posterior wing margin, with more than three rows of cells; RP 3/4 undulate and distally strongly diverging from MA; wing venation dense consisting of large number of cells; few polygonal groups of cells separated by veinlets and intercalary veins between RP 1 and IR1, IR2 and RP 3/4, and MA and MP; antenodal space longer than postnodal space; T with a crossvein; only two rows of cells in area between RP 1 and RP 2 basal of Pt; Rspl absent.

Position of Sinaktassia within the Petalurida. Sinaktassia falls in the Petalurida Bechly, 1996 because of the following synapomorphies: postnodal space very narrow, with many cells distal to Pt; pterostigmal brace vein shifted basal to Pt; IR1 long; wing space between RP 1 and RP 2 greatly expanded, with more than 8–9 rows of cells; forewing PsA hypertrophied; subdiscoidal triangle widened, forewing T transverse; forewing subdiscoidal triangle divided by cross-veins; more than two rows of cells in basal part of postdiscoidal area between level of distal angle of discoidal triangle and level of midfork ( Nel et al., 1998).

Sinaktassia differs from the Protolindeniidae Handlirsch, 1906 (type genus Protolindenia Deichmüller, 1886 ) in its pterostigmal brace less basally recessed, more numerous cells, and presence of groups of cells and secondary veins in areas between main veins. Sinaktassia shares with the Petalurodea Bechly, 1996 (Cretapetaluridae Nel et al., 1998 and Petaluroidea) the following synapomorphies: wings falcate, slender, and distinctly longer than 50 mm; Bqs-area distinctly narrowed. Sinaktassia shares no synapomorphy with the cretapetalurid Cretapetalura Nel et al., 1998: its basal oblique vein is not shifted basally; the distal side of its discoidal triangle is not angulated; and it has no convex intercalary vein in postdiscoidal space, unlike Cretapetalura. On the contrary, Sinaktassia has the synapomorphies of the Petaluroidea ( Aktassiidae + Petaluridae Needham, 1903 ), i.e. Pt elongated; in forewing the area between RP 3/4 and MA widened near posterior wing margin, with more than three rows of cells; RP 3/4 undulate and distally strongly diverging from MA. Sinaktassia has the synapomorphies of the Aktassiidae : Aktassiinae, and not those of the Petaluridae , i.e. very dense wing venation with a distinctly increased number of cells; characteristical pattern of veinlets and intercalary veins between RP 1 and IR1, IR2 and RP 3/4, and MA and MP; in forewing antenodal space is not shorter than postnodal space; Pt not extremely elongated and narrow and do not appear to be curved.

The second aktassiid subfamily Pseudocymatophlebiinae (type genus: Pseudocymatophlebia Nel et al., 1998) has an IR1 very long and straight but vanishing distally and an elongate forewing discoidal triangle, unlike Sinaktassia .