A New Genus of New Zealand Leaf-Hoppers (Jassoidea, Homoptera).
[Read before Nelson Philosophical Society, May, 1941; received by the Editor, January 29, 1941; issued separately, September, 1941.]
Leaf-Hoppers (Jassoidea) are poorly represented in the New Zealand fauna. The dominant group, representatives of which are often taken in general collecting, were considered by Myers (1923) to comprise species that belong to the genus Diedrocephala Spinola. This genus is included in the family Cicadellidae, termed by Myers the subfamily Tettigoniellinae. Tillyard (1926), whilst retaining this group in the Cicadellidae (Cicadellinae), placed the several species in the genus Tylozygus Fieb. (Fieb. appears by the author's correction to be a contraction.) It is certain not only that they do not belong to either of these genera, but that they are not cicadellids at all. Accordingly it is necessary to describe a new genus for their reception.
Genus Novothymbris nov.
Genotype: Diedrocephala zealandica Myers.
The head lies in two distinct planes; the dorsal surface is flat, whilst the ventral surface is slightly convex and lies at an acute angle to the crown. A distinct ridge separates the two surfaces. The anteclypeus is long and narrow, recuryed apically and extends beyond the maxillary plates. The lora are wide and the fronto-clypeus more or less parallel-sided. The antennal ledges are curved and not prominent and the frontal sutures distinct. These sutures extend beyond the antennae nearly as far as the anterior margin of the head. Fusion of the frons and post-clypeus is not complete and the identity of the former sclerite is distinct. The crown is wide and the coronal suture extends almost to the anterior margin, thus, but for a small anterior portion, the crown comprises solely the vertex. The ocelli are on the crown well away from the anterior border of the head. Anteriorly the pronotum is on a plane with the crown of the head, posteriorly it is slightly declivous. The tegmina are rounded apically, have very little development of an appendix and the venation is as shown in figure 5. In the wings R4+5 may be fused apically with M1+2, or these veins may be distinct. The hind tibiae are narrow and armed with two rows of strong spines; the spines of one of these rows are mounted on enlarged bases. There is also a row of long, slender spines. The male genitalia have long, fairly broad sub-genital plates, short narrow parameres, well-developed basal plates, an aedeagus without spines or processes and wide pygophores.
Myers described the following New Zealand leaf-hoppers, which he placed in the genus Diedrocephala; cassiniae, maorica, zealandica, tararua, dunensis, hinemoa, hudsonica. They are all now transferred to the genus Novothymbris and the the genotype selected is N. zealandica (Myers).
It is presumed that species in this genus were placed previously in the Cicadellidae because of the dorsal position of the ocelli. The present author is only one of several who have pointed out that in jassoid classification the position of the ocelli is a most unreliable character. The most dependable characteristics are comprised in the basic structure of the head (Evans, 1938). A consideration of the head structure of species belonging to the genus Novothymbris together with an analysis of other characters, particularly the armature of the hind tibia and the venation of the tegmen, makes it quite certain that this genus belongs to the Family Thymbridae (Evans, 1939). This family contains the following genera, all of which apart from Novothymbris are confined to Australia: Thymbris Kirk., Alseis Kirk., Epipsychidion Kirk., Putoniessa Kirk., Macroceps Sign., Rhotidus Stal, Rhotidoides Evans, Hackeriana Evans, and Mitelloides Evans.
The ocelli in species in certain of these genera, such as Putoniessa, are ventral, in others such as Rhotidoides, they are marginal, whilst they are dorsal in Rhotidus and Hackeriana. Nevertheless in every species in the family they are on the vertex, usually just above and to the sides of parallel frontal sutures, and posterior to a well-defined transverse ridge that extends across the head to the eyes on each side, This ridge is ventral in Putoniessa, and the head is on one plane on either side of it; it is marginal in Rhotidoides and separates the ventral surface of the head from the vertical crown. In Novothymbris it is apical and acutely separates the flat crown from the ventral surface of the head. Species in all these genera have a recurved produced ante-clypeus, tegmina with very small appendices and similar venation, and hind tibiae with the same characteristic armature of spines. Figures are given (figs. 1–5) in order to show the essential structural features of two species of Novothymbris. These should be compared with those given in earlier papers (Evans, 1937, 39) illustrating species in related Australian genera.
Evans, J. W., 1937. Australian Leaf-Hoppers, Pt. 5, Pap. Roy. Soc. Tas., 1930–37; 51.
—— 1938. The Morphology of the Head of Homoptera, Pap. Roy. Soc. Tas., 1937–38; 1.
—— 1939. A Contribution to the study of the Jassoidea, Pap. Roy. Soc. Tas., 1938–39; 19.
Myers, J. G., 1923. A Contribution to the study of New Zealand Leaf-Hoppers and Plant-Hoppers, Trans. N.Z. Inst., 54; 407.
Tillyard, R. J., 1926. The Insects of Australia and New Zealand, Angus and Robertson, Sydney.