Helianthecis Gagné, 2016

Gagné, Raymond J., 2016, Three new genera and three new species of Nearctic Lasiopteridi (Diptera: Cecidomyiidae: Cecidomyiinae) from Asteraceae and Caprifoliaceae, and the tribe Rhopalomyiini subsumed under Oligotrophini, Zootaxa 4158 (3), pp. 403-418 : 405-409

Helianthecis Gagné , new genus

Figs 4 , 7–18 .

Diagnosis. Were it not for their fully developed mouthparts ( Fig. 7 ), adults of the new genus would pass for a Rhopalomyia . The two genera resemble one another in the following suite of characters: C is continuous across its juncture with R4+5; empodia reach the bend in the claws; abdominal tergites bear lateral setae (secondarily lost in some Rhopalomyia spp.); the female eighth tergite, while lengthy, is not divided longitudinally; the gonostylus is completely covered with microtrichia; and the ventral part of the gonocoxal mediobasal lobe is blunt apically. In Rhopalomyia the mouthparts are probably non-functional. The labella are reduced in size and vestiture and the palpi have only one or two segments. In Helianthecis the labella are fully developed and the palpi retain all four segments. Larvae of the two genera are distinct: Helianthecis is the more plesiomorphic with a fully developed spatula, five lateral papillae on each side of the thoracic midline, and eight terminal papillae; Rhopalomyia has a foreshortened spatula when one is present, at most two lateral papillae on each side of the thoracic midline, and only two or four terminal papillae.

Description. Adult: Head ( Fig. 7 ): Eyes connate, 6–7 facets long at vertex; facets circular, contiguous except slightly farther apart laterally near level of antennal bases. Antenna: ventral aspect of scape with extensive covering of setae and scales; pedicel evenly covered with setae; first and second flagellomeres connate. Male antenna ( Fig. 8 ) with 13 (last two connate) to 15 flagellomeres, all but apical flagellomere with necks about half length of nodes; circumfila consisting of complete basal ring and partial distal ring connected by two vertical strands; short, straight setae encircling base below proximal circumfilum, many long, basally curved setae from hooded alveoli situated between circumfilar rings, these present chiefly on venter. Female antenna ( Fig. 9 ) with 14 (last two connate) to 17 flagellomeres, as for male but without necks and 2 complete circumfilar rings. Frons extensively covered with setae and scales. Labrum triangular, with short setae ventrally. Labella hemispherical in frontal view, fused medially, with several, short, strong setae of uniform length. Palpus of 4 segments, first and second ovoid, not much longer than wide, third and fourth narrower, about twice as long as wide; first segment with long setae, the remaining segments variously covered with scales and setae, including short, strong setae on medial surface similar to those on the labella.

Thorax: Scutum with 4 longitudinal rows of setae with a few scales intermixed, the 2 dorsocentral rows broadest anteriorly, tapering posteriorly and vanishing before scutellum, the 2 lateral rows situated at midlength of scutal edge. Scutellum covered with setae anteromedially and laterally. Anepisternum with a few scales dorsally; anepimeron setose; pleura otherwise bare. Wing ( Fig. 4 ): C not broken at junction with R4+5; R4+5 nearly straight, reaching C near wing apex; CuA forked. Acropods ( Fig. 10 ): tarsal claws strongly curved beyond midlength, without basal tooth; empodia as long as claws; pulvilli about 1/3 length of claws.

Male abdomen ( Figs 11–14 ): Tergites first through eighth and sternites second through seventh with anterior pair of trichoid sensilla, the pair closely approximated on sternites. First through sixth tergites rectangular, all with mostly single, elongate posterior row of setae, many lateral setae near midlength, and mostly covered elsewhere with scales and short setae; seventh tergite trapezoid, foreshortened, lacking the posterior row of setae, otherwise as for preceding tergite; eighth tergite half the width of preceding, setae and scales sparce. Sternites quadrate, second through eighth each with mostly double row of setae along posterior margin, preceded by a more weakly sclerotized area with few short setae and scales, and towards midlength, more large and small setae mixed with scales not extending to pair of trichoid sensilla. Pleura covered with long, narrow scales. Terminalia ( Figs 11–13 ): cercus ellipsoid, with several mostly ventral setae; hypoproct deeply concave apically, each resulting lobe with single strong seta; lateral part of gonocoxite cylindrical, longer ventrally, mediobasal lobe subdivided, the shorter dorsal section long-microtrichose, ventral section closely clasping aedeagus, covered with shorter microtrichia, with 3–4 apical setae set on raised bases; gonostylus cylindrical, of approximately equal diameter throughout, with scattered setae and entirely covered with microtrichia, tooth apical, much narrower than width of gonostylus, consisting of closely arrayed spines; aedeagus slightly longer than gonocoxal lobes, dorsoventrally narrowed and dorsally recurved apically; gonocoxal apodeme wide, united.

Female abdomen ( Fig. 15 ): Tergites and sternites with anterior pair of trichoid sensilla, closely approximated on sternites; eighth sternite indistinct, with no trace of trichoid sensilla. First through sixth tergites and pleura as in male, except posterior setal row of tergites interrupted medially; seventh tergite quadrate, as long and about half width of sixth, with mostly 2 rows of posterior setae, several setae medially at midlength, otherwise bare except for anterior trichoid sensilla; eighth tergite forked anteriorly, then abruptly tapering and narrow, bare except for anterior trichoid sensillum on each anterior arm and scattered short setae posteriorly. Sternites generally as for male, except no sign of eighth. Pleura covered with long, narrow scales. Ovipositor: elongate, cylindrical, entirely microtrichose, with evenly spaced short setae; protrusible part with thin lateral sclerites, its length (including cerci) about 4.5 times length of seventh tergite; cerci fused, ovoid, evenly covered with setae, several distal setae peglike; hypoproct nearly twice as long as wide, with 2 short, apical setae.

Pupa ( Fig. 16 ): Integument hyaline. Antennal bases rounded, not differentially sclerotized or modified into anteriorly pointed projections. Vertex on each side with long seta situated on conspicuously raised base. Face smooth, without lobes, with pair of centrally placed, setose papillae and triplet of short-setose papillae on each side near palpal bases. Prothoracic spiracle short. Abdominal terga, pleura and sterna evenly covered with short spiculae.

Larva, third instar ( Figs 17–18 ): Cylindrical. Head capsule conical, apodemes less than half length of capsule; antennae about as long as wide. Spatula robust, clove-shaped, with 2 slightly rounded, anterior teeth. Position and number of papillae as in generalized Lasiopteridi (cf. Gagné 1989, p. 67) except outer group of lateral papillae on each side of midline lacking the asetose papilla and all setae very short, those on eighth and terminal abdominal segments longer than setae on preceding segments. Integument entirely covered with rounded verrucae.

Type species, Helianthecis capitum Gagné.

Etymology. The name Helianthecis is formed from the host genus Helianthus (Greek for sunflower) and cecis (Greek for gall). The juncture of the two words is truncated to trim a syllable. The gender is feminine.

Remarks. The male and female abdomens of Helianthecis are generally similar to some found in Rhopalomyia , but the fully developed, apparently functional mouthparts, the strong clove-shaped larval spatula and the nearly full complement of larval papillae show a discontinuous gap between the two genera. Helianthecis can be separated from Chiosperma and Lonicerae , the two other genera described here, by its four-segmented palpus, short pulvilli, elongate ovipositor with fused female cerci, and the ovoid gonostylus.

Figures

FIGURES 4 – 6. Wings. 1, Helianthecis capitum. 2, Lonicerae russoi. 3, Chiosperma turgidum. Line = 1 mm.

FIGURES 7 – 14. Helianthecis capitum. 7, Head (frontal, flagella removed). 8, Male third flagellomere (ventral). 9, Female third flagellomere (ventral). 10, Acropod (lateral). 11, Male terminalia (lateral). 12, Same, one gonopod removed (dorsal). 13, Same (ventral). 14, Male sixth (on left) through eighth abdominal tergites.

FIGURES 15 – 18. Helianthecis capitum. 15, Female abdomen, sixth segment to cerci (dorsolateral), with details of eighth tergite, fused cerci and seventh sternite. 16, Pupal anterior parts (ventral). 17, Larval spatula and associated papillae. 18, Larval eighth and terminal segments (dorsal).