Aethodelphax, Bartlett, Charles R., 2011

Bartlett, Charles R., 2011, Aethodelphax prairianus gen. et sp. nov. (Hemiptera: Delphacidae) and seven congeneric species from North American Delphacodes, Zootaxa 2837, pp. 48-66 : 50-51

Genus Aethodelphax gen. nov.

Type species. Aethodelphax prairianus sp. nov., by present designation.

Diagnosis. The narrow, produced crown, pediform parameres with enlarged basal angles (most prominent in lateral aspect) and the aedeagal suspensorium with an elongate and sometimes reflexed dorsal connection to segment 10 will separate Aethodelphax from all other Delphacini .

Description. Pale, usually uniformly stramineous although darker markings may be present especially on thoracic pleuron and lateral portions of abdomen. Head slightly narrower than prothorax. Vertex slightly longer than wide, medially slightly produced; carinae of head evident, obscure at fastigium, concolorous to head. Frons subparallel, widest in ventral half; fork of median carina of frons approximately at fastigium. Antennae with pedicel twice as long as wide, weakly curved caudad, with close-set pustules bearing sensory spines, pustules forming a double row of 3 each on dorsal surface, one pustule on posterior surface, 1–2 smaller pustules on anterior surface ( Figs. 10 A–B), and a ring of 7 close-set pustules around tip of pedicel with the dorsal pustule much smaller than others ( Fig. 10 F); anterior rim of scape just below midline with a distinct campanuliform sensillum ( Fig. 10 C). Lateral carinae of the pronotum curved laterally behind eye, not reaching (or obscurely attaining) the hind margin. Most individuals brachypterous, tegmina apically rounded, shorter than abdomen leaving male pygofer and usually additional segments exposed in dorsal view. Macropters with wings clear, except some veins darkened near apex. Macropterous wing venation varied among individuals (particularly with respect to the number and arrangement of peripheral veins of the radius and anterior cubitus), but usually bearing 1 subcostal branch, 3 radial (R1, R2+3 and R4+5), 1 media, and 3 anterior cubitus branches (Cu1a, Cu1b, Cu2); nodal line in distal ¾ of wing, outer subapical cell longer than inner subapical cell. Hind leg pectens (apical spinulation) 5 (3+2) (tibia), 7 (5+2) (basitarsus) 4 (2nd tarsomere); calcar flattened, ventrally concave, approximately 2/3 or more length of basitarsus, bearing 15+ fine black-tipped teeth on posterior margin, without distinct apical tooth.

Genitalia with parameres pediform, in lateral view basal angles well-developed and caudally projecting; in caudal view inner angle well developed, outer angle developed or rounded. Pygofer opening in caudal view just wider than long, with rounded to carinate margins; in lateral view rounded or with ventral portion somewhat projecting. Genital diaphragm well-developed, in most taxa narrowing medially with armature well-developed and dorsocaudally projecting (e.g., Figs. 9 C–D; reduced in A. caninus , modified in A. aetocephalus ). Aedeagus varied, but usually laterally flattened; straight, sinuate, or ventrally curved; often bearing large teeth or conspicuous foliations. Aedeagal suspensorium conspicuous, encircling aedeagus, approximately quadrate between aedeagus and segment 10. Segment 10 bearing a pair of short, widely separated processes from caudoventral corners, some species with second pair of teeth near ventral midpoint in lateral view.

Remarks. Aethodelphax superficially resembles several taxa of pale Delphacini such as Elachodelphax , Muirodelphax and pale species remaining in Delphacodes . Elachodelphax is generally a northern genus, Holarctic, with dark genae (and other markings). The opening of the male pygofer of Elachodelphax is distinctly carinate and wider than long, and the genital diaphragm medially keeled. The parameres of Elachodelphax lack the prominent basal angle of Aethodelphax and are usually short (exception E. paransera ); the aedeagus of Elachodelphax usually has a pronounced enlargement in the basal portion and the processes of segment 10 are approximated, at least distally.

The antennae of Aethodelphax most closely resemble those of Elachodelphax paransera (transferred to Elachodelphax from Delphacodes by Hamilton & Kwon 2010), particularly in the reduction of the central pustule on the ring around the antennal tip, thus allowing the antennae to be raised to their fullest extent ( Figs. 10 B, C, F). These and other advanced Delphacini have a remarkable antennal structure apparently unique to Delphacidae : a campanuliform sensillum on the scape ( Fig. 10 C, inset) similar to, but much smaller than, that of Cercopidae ( Liang & Fletcher 2002) . Continuing research (by KGAH) suggests that this feature is widespread in the Delphacini but probably does not occur within genera with large numbers of scattered pustules.

Muirodelphax ( sensu Hamilton & Kwon 2010 ) is also superficially similar, but males usually bear dark markings and the antennal pustules are smaller and farther apart. Parameres of Muirodelphax lack the pronounced basal angles of Aethodelphax , and the genital diaphragm is a simple dorsal thickening with a median keel. Also unlike Aethodelphax , segment 10 of male Muirodelphax lacks processes (or they are represented by teeth).

Aside from geography, Delphacodes s.s. differs from Aethodelphax most conspicuously in the former genus having a uniformly dark coloration (testaceous to brown), and the wings of the macropter of available specimens are weakly infuscated with a variably developed dark spot at the apex of the clavus. The lateral carinae of the pronotum clearly reach the hind margin in Delphacodes s.s., as it does in the Nearctic Delphacodes plenatra Beamer , and the genera Megamelus Fieber , Delphacinus Fieber , and Megamelanus Ball. The parameres are simple, forcepslike, and lacking the conspicuous basal and outer angles found in Aethodelphax . The genital diaphragm armature of most Delphacodes s.s. possesses a subdorsal, caudally projected, process (see Asche & Remane 1983, fig 9a; instead of dorsal and dorsocaudally directed), except D. schinias Asche & Remane 1983 , and D. framarib Asche & Remane, 1983 that have a quadrate dorsal projection (see Asche & Remane 1983, figs. 15A, B); these taxa have a median tooth on the ventral opening of the pygofer, absent in Aethodelphax .

The species of Aethodelphax have so far been recorded from central and southeastern US states, except A. caninus from arid parts of Arizona and Mexico. The only species in this genus frequently encountered is the type species, known from 167 specimens. Among the seven previously described species, very few (only 30) specimens were observed beyond the 50 paratypes reported by Beamer in his original descriptions. The new species was obtained in native prairie habitats. The longest series (79 specimens) were taken by Ross sweeping, although they have also been taken by vacuum sampling. We feel it is probable that Aethodelphax is associated with grasses in prairie and longleaf-pine savannah habitats, although only two species have been reported from specified grasses: Andropogon in Illinois and Muhlenbergia in Mexico.

Etymology. Aethes (Greek, unusual, strange), with the genitive case-ending “- es ” removed, combined with Delphax (referring to the type genus, derived from the Greek delphax [small pig]), with a combining connective ‘o’. We regard the genus name as masculine, consistent with ICZN’s (1961) statement regarding the gender of Delphax .

Figures

FIGURE 9. Genital diaphragm armature. A. Aethodelphax megadontus, caudal view; B. A. paraparvulus, caudal view; C. A. sagitattus, caudal view; D. A. sagitattus, lateral view (genital diaphragm hatched); E. A. paraparvulus, lateral view.

FIGURE 10. Scans of antennal characters. A. lateral aspect of head and prothorax of Aethodelphax concavus; B. tip of antenna of Aethodelphax prairianus; C. same, of Caenodelphax teapae; D. same, of Elachodelphax paransera; E. anterior surface of pedicel of Aethodelphax megadontus; F. same, of Muirodelphax parvula; G. same, of Caenodelphax teapae; H. same, of Elachodelphax paransera, with inset showing enlargement of campaniform sensillum on scape.