Characters, distribution, and food plants of leafhopper species in Thamnotettix group

Abstract does not appear. First page follows.

Introduction

Some years ago three species (Severin, 1929), (1934)4 and a biological race (Severin, 1940) of one of these leafhopper species were reported to transmit the California aster-yellows virus. Recently, (DeLong and Severin (1945), (1946), (1947a), (1947b) recorded thirteen additional leafhopper vectors of the virus. The present paper deals with the characters, distribution, and food plants of eight more leafhopper vectors, two of which have been previously mentioned in the literature (Severin, 1934). In a companion paper (Severin (1948)) discusses the transmission of the virus by these eight leafhopper species.

The genus Thamnotettix was erected by (Zetterstedt (1840)) to include European species, and Cicada prasina Fallen was designated as the type. The early American workers placed a large number of American species in this genus as they were described. In recent years several new genera have been described to include certain groups of closely related American species formerly in the genus Thamnotettix. The species treated in the present paper have been placed in three genera described by (Ball (1936)). These are Idiodonus, Colladonus, and Friscananus. There is little doubt that these species in the three genera are closely related; they may belong to a single genus. The color patterns will usually distinguish them, but the genital structures are similar in both the males and the females of the species concerned. The females usually bear a median sunken spatulate process on the last ventral segment which varies in width, length, and the degree of production beyond the posterior margin in different species. The males may be distinguished by the shape of the style and the length and position of the spine on each side of the caudal margin of the pygofer.

Idiodonus Heidemanni (Ball)

Idiodonus heidemanni (Ball) is blunt-headed and has a general color of grayish green, sprinkled with minute red spots. It is 4 mm long.

The vertex (fig. 1, A) is broad, bluntly produced, and about twice as wide at the base between the eyes as the median length.