Rhopalomyia cruziana Felt 1908

Dorchin, Netta, Mcevoy, Miles V., Dowling, Todd A., Abrahamson, Warren G. & Moore, Joseph G., 2009, Revision of the goldenrod-galling Rhopalomyia species (Diptera: Cecidomyiidae) in North America, Zootaxa 2152, pp. 1-35 : 11

Rhopalomyia cruziana Felt 1908

Rhopalomyia cruziana Felt 1908: 366 .

Adult: Antenna with 15 flagellomeres in male, 14 in female; necks of male flagellomeres III–VII 0.62–1.00 times as long as nodes, female flagellomeres without necks. Palpus appears to be 2-segmented although the mounting orientation of the type specimens makes this difficult to establish. Wing length 1.7–1.8 mm in male, 1.5 mm in female. Male terminalia ( Fig. 15 ): gonocoxite cylindrical, setose and setulose, with setose mediobasal lobe; gonocoxal apodeme undivided, somewhat narrowed anteriorly; gonostylus short and stout, setose and setulose throughout, with brush-like tooth; aedeagus conical, rounded distally; hypoproct with small notch, setulose; cerci separated by triangular notch, setose and setulose. Female abdomen (Fig. 31): tergite 7 rectangular, with weak sclerotization in mid-anterior part, with two anterior trichoid sensilla, a row of setae posteriorly, and few setae mesally; tergite 8 narrow Y-shaped, proximal arms considerably shorter than shaft, with two anterior trichoid sensilla; ovipositor 5.4 times as long as tergite 7.

Pupa: unknown.

Type material: Rhopalomyia cruziana Felt. Syntypes: 1 male, 1 female, USA, CA, Santa Cruz Mts., VIII/1890, ex. Solidago sp., unspecified collector, Felt # C942, deposited in Felt Collection.

Host: Solidago sp.

Gall and biology: The floret/capitulum galls of this species have not been described in detail and the host plant is unknown, hence it is impossible to determine whether this species is distinct and who its relatives among the Rhopalomyia spp. on goldenrods are. According to the information given by Felt (1915), the galls were collected in Santa Cruz Mts. in California in August 1889 and adults emerged from them “before May 1890 ”.

Remarks: This is the smallest Rhopalomyia species from goldenrods. It generally resembles the other Rhopalomyia species that develop in goldenrod capitula but has fewer antennal flagellomeres (the smallest number among goldenrod Rhopalomyia spp.), a considerably shorter ovipositor, and the shortest arms of the Y-shaped 8th tergite in the female. The species appears to have 2 palpal segments, as do the other 3 species from goldenrod capitula, although the mounting orientation of the only two known individuals makes this difficult to ascertain. The very long necks of the male flagellomeres resemble those of R. racemicola but the male terminalia are most similar to those of R. guttata , from which it differs in having notched rather than entire hypoproct. The general similarity of this species to the other species from goldenrod capitula supports the assumption that it was indeed reared from capitula, but establishing the nature of the galls and the identity of the host plant requires additional collecting on goldenrods in the relevant area.

Figures

FIGURES 9 – 19. Male terminalia (in dorsal view unless otherwise noted). 9. Rhopalomyia anthophila. 10. Rhopalomyia anthophila, left gonopod, ventral. 11. Rhopalomyia bulbula. 12. Rhopalomyia guttata. 13. Rhopalomyia capitata. 14. Rhopalomyia clarkei. 15. Rhopalomyia cruziana. 16. Rhopalomyia fusiformae. 17. Rhopalomyia hirtipes. 18. Rhopalomyia gina. 19. Rhopalomyia gina, lateral. Scale bars = 0.1 mm