Tardilly dunstani ( Tillyard), 1922

Lambkin, Kevin J., 2019, Mesodiphthera Tillyard, 1919, from the Late Triassic of Queensland, the oldest cicada (Hemiptera: Cicadomorpha: Cicadoidea: Tettigarctidae), Zootaxa 4567 (2), pp. 358-366 : 365

Tardilly dunstani ( Tillyard), 1922 , comb. nov.

( Figs 10, 11 )

Mesodiphthera dunstani Tillyard, 1922: 462 , text-fig. 81.

Ligavena dunstani (Tillyard) , Hamilton 1992: 427.

Material. Holotype tegmen GSQ137a (now in the Queensland Museum), Denmark Hill.

Description. Tegmen about same size as M. prosboloides ; M3 with 2 branches, M4 simple; CuA sharply angled at, and forking a short distance beyond, nodal line; CuA fork almost 90˚; CuA2 straight; no colour pattern detected.

Notes. The type of T. dunstani ( Fig. 10 ) is quite distorted and does not lie flat on the rock. The post-nodal area is bent upwards, and the clavus is bent downwards. When this is taken into account, it would be about the same size as T. prosboloides . As a result of this distortion, the pre-nodal section of CuA has been displaced anteriorly, RA2 appears up-curved, and the post-nodal section of M1+2 has been displaced posteriorly. The slightly darker areas in the photograph of T. prosboloides ( Fig. 8 ) are shadows caused by the uneven rock surface and not colour patterns, while the different colour shades in the photograph of T. dunstani are the result of differential iron oxide staining of the specimen. Hamilton (1992) placed both species in Ligavena Hamilton, 1992 , a genus based on a Cretaceous species from Victoria. He ascribed Ligavena to a new family, Ligavenidae , and new superfamily, Ligavenoidea, of the Cicadomorpha, although these were subsequently synonymised with the Hylicellidae and Hylicelloidea by Shcherbakov (1996). The presence of a clear nodal line and their similarity to Mesodiphthera , however, confirm that the two species belong to the Tettigarctidae .

Figures

FIGURES 8–11. 8, 9, Tardilly prosboloides (Tillyard), holotype, GSQ89b (Fig. 8 shows the mesonotum at lower left of tegmen); 10, 11, Tardilly dunstani (Tillyard), holotype, GSQ137a.