Chionomus Fennah, 1971

Weglarz, Kathryn M. & Bartlett, Charles R, 2020, A revision of the planthopper genus Chionomus Fennah (Hemiptera: Fulgoroidea: Delphacidae), Zootaxa 4811 (1), pp. 1-63 : 9-10

Genus Chionomus Fennah, 1971

Chionomus Fennah, 1971: 323-324 .

Type species. Delphacodes havanae Muir & Giffard, 1924 , by original designation.

Description. Color. General body color brunneous to black, legs paler, white to stramineous or light brown; with carinae of the head, paranota, and scutellum pale. Pronotum often with characteristic wide white band along posterior margin (reduced or lacking in C. banosensis , C. gluciophilus , C. quadrispinosus ), paranota paler along margins or more broadly, pronotal carinae contrasting in color in some species ( C. bellicosus , C. dissipatus ). Mesonotum dark, C. bellicosus and C. pacificus with median vitta or carinae lightened, scutellum always white except in males of C. dolonus n. sp. Wings clear with fuscous mark near apex of clavus (the ‘claval spot’). Structure. Head narrower than pronotum, vertex quadrate, approximately as wide as long (except C. herkos n. sp.); carinae distinct, stem of Y-shaped carina weak, median carinae of vertex converging at fastigium. In lateral view, genal carinae angled anteroventrad to meet anterior margin of clypeus, fastigium rounded. Front with carinae distinctly contrasting with darkened foveae, lateral margins of frons parallel to subparallel, widest between midpoint of compound eyes to just below ventral edge; median carina distinct, forked at fastigium. Antennae short, not exceeding posterior margin of tegulae, circular in cross-section, segment I just longer than wide, II longer than I. Pronotal carinae weak, median carinae of pronotum reaching posterior margin, lateral carinae curved, diverging posteriorly, not reaching posterior margin. Mesonotum with carinae weak in macropters, median carinae never reaching scutellum, lateral carinae diverging, reaching hind margins, more pronounced in brachypters. Legs quadrate in cross-section, hind tibiae with two lateral teeth, one just distal to joint with femur and second near midpoint. Calcar foliaceous, about half length of basitarsus. Veins of macropter distinct, sparsely setaceous; R+Sc 3 branched, M 3 branched, CuA 3 branched, CuP unbranched, claval veins fusing mid-length ( Figure 2 ). Tegmina of brachypter nearly covering abdomen, distal apices rounded. Abdomen compressed dorsoventrally, tapering caudad to truncate apex in males. Male pygofer longer ventrally than dorsally, broad in lateral view; in caudal view opening round or mildly dorsoventrally compressed; dorsolateral margins of pygofer may be produced (i.e., C. gluciophila , C. herkos ) but usually truncate in lateral view, except C. dolonus with a caudal tooth. Diaphragm and armature strong, well-developed, dorsal margin concave producing large inverted triangular or trapezoidal opening between diaphragm and segment X; armature distinctly projecting caudad, often bilobed, indented, or caudally produced where aedeagus rests. Aedeagus tubular, parallel sided, except C. havanae , C. bellicosus , C. herkos ; slightly to distinctly curved dorsad, gonopore subapical and dorsal. Parameres flattened apically but inner angle may be slightly curved or caudally produced ( C. banosensis , C. dissipatus , C. herkos ), basal angle strong, widest in basal third (except C. tenae ), lateral margins concave, widened apically. Segment X quadrate, bearing zero, two, or four processes on ventrocaudal margin, ventrally directed; segment XI shorter than segment X.

Remarks. The general coloration of Chionomus is helpful for genus recognition but is not definitive. Also, females may be paler than males. A similar general coloration, including the dark marking at the claval apex and the pale caudal margin of the pronotum can be found in other genera (e.g., Javesella Fennah, 1963 , Falcotoya Fennah, 1969 , Opiconsiva Distant, 1917 ). However, these genera can be diagnosed by male genitalia. Falcotoya lacks the produced armature of the diaphragm and possesses a strongly decurved aedeagus. Opiconsiva differs in having the dorsocaudal margin of the pygofer strongly expanded and the processes on segment X closely approximated. Opiconsiva is restricted to the Eastern Hemisphere and Hawaii with the exception of Opiconsiva tangira (Matsumura, 1910) , recently reported by Halbert (2016), and Opiconsiva anacharisis ( Fennah, 1969) , reported as Harmalia anacharsis by Wooten et al. (1993), recorded in Florida. Javesella lacks the claval spot and the opening of the pygofer is very broad with widely diverging parameres and the processes on segment X always closely approximated. Isodelphax Fennah, 1963 , also shares the same general appearance but this genus lacks the claval spot and the parameres are strongly diverging apically with a strongly projected basal angle. Isodelphax also tends to have a dark antennal segment I, which is usually paler (yellowish to light brown) in Chionomus .

Some Chionomus species are very common and are readily collected at lights. Chionomus puellus is abundant (with more than 5,000 specimen records in the Tri-Trophic TCN database) and widely distributed in the eastern US. Chionomus havanae and C. balboae can be abundant over much of the Neotropics. Despite this, the biology of these species are poorly known.

Etymology. The original author did not indicate the gender or derivation of the name Chionomus . It appears to stem from the Greek noun chionos, meaning “snow”, possibly a reference to the whitened posterior pronotum margin, with –[i] mus to indicate possession. The names of three species originally placed in Chionomus do not indicate gender, as they are latinizations of proper nouns in the genitive. Following article 30.2.4 of the Code of Zoological Nomenclature ( ICZN 1999) the name is treated as masculine (consistent with a - us Latin ending).

Figures

FIGURE 2. Wing venation of Chionomus havanae.