Mesojassus australis ( Evans, 1956 ) Lambkin, 2020

Lambkin, Kevin J., 2020, Revision of Mesojassus Tillyard, 1916, from the Late Triassic of Queensland (Hemiptera: Cicadomorpha: Membracoidea: Archijassidae), Zootaxa 4718 (3), pp. 413-422 : 417-419

Mesojassus australis ( Evans, 1956) , comb. nov.

( Figs 5–11 )

Triassocotis australis Evans, 1956: 194 , fig. 5L; Carpenter, 1992: 258–259, fig. 162.3; Jell, 2004: 39, 2 unnumbered figs; Lambkin 2019: 392.

Triassocotis amplicata Evans, 1961: 16 , fig. 1G; Jell, 2004: 39; Lambkin, 2019: 392; syn. nov.

Hylicella reducta Evans, 1956: 196 , fig. 7B; Carpenter, 1992: 233; Jell, 2004: 45; Lambkin, 2019: 392; syn. nov.

Hylicellites reducta ( Evans, 1956) : Becker-Migdisova 1962a: 95, fig. 9.

(partim non) Triassocotis australis: Evans, 1961: 16 , fig. 1E (specimen QMF3687 = Mesojassus ipsviciensis Tillyard ).

Material. Holotype tegmen UQC1553/1554, holotype tegmen of Triassocotis amplicata QMF3689a/b, holotype tegmen of Hylicella reducta UQC1452/1453, all Mount Crosby. Twenty-six additional tegmina: QMF: 60085, 60086, 60087a/b, 60088, 60089, 60090, 60091, Mount Crosby; 13626a/b (+ pronotum), 60070, 60071, 60072, 60073, 60074, 60075, 60076, 60077a/b (+ scutellum), 60078, 60079, 60080, 60081a/b, 60082a/b, 60083, 60084a/b, Dinmore; ACC: I.28, I.130, Mount Crosby, I.29 a/b, Dinmore.

Description. Tegmen 10.2–13.4 mm long (holotype 11.1, holotype of T. amplicata 12.5, holotype of H. reducta 10.2), 3.5–4.6 mm wide, length/width 2.9–3.3; no colour pattern detected, except in several Dinmore specimens which appear to have a dark shading across the entire tegmen ( Fig. 8 ), or to be 2-toned with variable dark and pale areas ( Figs 5, 7 ).

Notes. Mesojassus australis differs from the type species only in its larger size. The Mount Crosby and Dinmore specimens of the species exhibit similar size ranges. The apex of the holotype of T. australis is evenly rounded, not tending to lanceolate as illustrated by Evans (1956, fig. 5L). Three specimens, the holotypes of T. australis and T. amplicata , as well as QMF60091, differ from the rest in having an additional M branch, on M 3 in both holotypes ( Evans 1956, fig. 5L), and on M 4 in QMF60091 ( Fig. 10 ). The presence of this additional strengthening vein in the tegmen may be attributable to size, at least in the holotype of T. amplicata and QMF60091, which are two of the larger specimens of the species. The holotype of T. australis is additionally aberrant in having a three-branched RA ( Evans 1956, fig. 5L), unlike any other of the long series of specimens of either species of the genus in which RA is always two-branched (and never simple, as incorrectly recorded by Evans (1961, fig. 1G) in T. amplicata ). It might be suggested that these venational variations may represent distinct species, but this would require the creation of three additional species names based only on single specimens, among an otherwise consistent series of 29 specimens. In this light, and until substantial new material demonstrates the contrary, the three specimens are herein considered as simply individual venational variants of M. australis .

The holotype specimen of H. reducta is not well preserved but careful examination confirms it as simply a smaller specimen of M. australis . Contrary to Evans’s description and illustration (1956, fig. 7B), there is only one r-m, in the usual position for Mesojassus , the apical area of M 3+4 is not preserved, and CuA is of standard Mesojassus form, not fused with M 3+4, but connected with it by a short m-cua.

Figures

FIGURE 8. Mesojassus australis (Evans), Dinmore, composite of QMF60081a (part), and extreme apex of counterpart 60081b (mirrored), entirely darkly shaded.

FIGURES 5–7. Mesojassus australis (Evans), Dinmore: 5, 6, QMF60073 (mirrored), narrower specimen with 2-tone coloration; 7, QMF60075 (mirrored), broader specimen with 2-tone coloration.

FIGURES 9–11. Mesojassus australis (Evans), Mount Crosby: 9, QMF60087a; 10, QMF60091 (mirrored), larger specimen with 2-branched M4; 11, QMF60089, showing clearly preserved basal cell.