Rhopalomyia inquisitor 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 : 18-19

Rhopalomyia inquisitor Felt 1908

Rhopalomyia inquisitor Felt 1908: 364 .

Adult: Antenna with 18 flagellomeres in male, 17 in female; necks of male flagellomeres III–VII 0.75–0.77 times as long as nodes, necks of female flagellomeres 0.39–0.55 times as long as nodes. Palpus 1-segmented, short, cylindrical, about 1.5 times as long as wide. Wing length 1.8 mm in male, 2.4 mm in female. Male terminalia ( Fig. 20 ): gonocoxite wide, stout, setose, with setose mediobasal lobe; gonocoxal apodeme proximally divided into two slender arms; gonostylus curved in posterior margin, more or less straight in anterior margin, narrowed gradually toward apex, setose and setulose, with brush-like tooth; aedeagus almost rectangular, slightly widened and rounded distally; hypoproct almost rectangular, entire, setulose; cerci wide, rounded, separated by a wide notch, setose and setulose. Female abdomen (Fig. 36): tergite 7 rectangular, with two anterior trichoid sensilla and several setae posteriorly and mesolaterally; tergite 8 wide Y-shaped, proximal arms about half as long as shaft, each with anterior trichoid sensillum; ovipositor 7.4 times as long as tergite 7.

Pupa: unknown.

Type material: Rhopalomyia inquisitor Felt. Syntypes: 1 female, 1 male, USA, W. Nyack, NY, 25/IX/ 1907, E.P. Felt, ex. S. gigantea, Felt # a1705a, deposited in Felt Collection.

Host: Solidago gigantea

Gall and biology: Felt (1908) described this species from a single male and a single female and speculated ( Felt 1915) that it develops as an inquiline in galls of R. capitata . However, we did not find any signs of its presence in galls of R. capitata . Given the morphological similarity of R. inquisitor adults to those of R. clarkei , it is possible that R. inquisitor is not an inquiline but, rather, induces inconspicuous conical galls that escaped Felt’s attention. In the present study we found such galls on leaves of S. gigantea ( Fig. 67 ), including on modified leaves composing the bud galls of Dasineura folliculi . This finding supports our hypothesis that R. inquisitor may well be the species responsible for these galls, but the galls were rare and we were unable to rear adults from them (see details below, under Rhopalomyia sp.). A comparison of such adults with the type specimens of R. inquisitor would be the only way to determine whether the galls we found are indeed those of R. inquisitor .

Remarks: The adults of R. inquisitor are similar to those of R. clarkei , but the male gonopods in R. inquisitor are less bulky, its ovipositor is longer, the arms of tergite 8 of the female abdomen are relatively longer, and the female flagellomeres have significantly longer necks.

Figures

FIGURES 20 – 25. Male terminalia (in dorsal view unless otherwise noted). 20. Rhopalomyia inquisitor. 21. Rhopalomyia lobata. 22. Rhopalomyia racemicola. 23. Rhopalomyia solidaginis. 24. Rhopalomyia solidaginis, ventral. 25. Rhopalomyia thompsoni. Scale bars = 0.1 mm

FIGURES 62 – 69. Rhopalomyia leaf and stem galls. Figs. 62 – 64. Rhopalomyia clarkei galls on Solidago rugosa; 62. Young gall. 63. Mature galls. 64. Galls on underside of leaf. 65. Rhopalomyia clarkei galls on stem and leaf of Solidago altissima (photo by M. Wise). Figs. 66 – 67. Rhopalomyia sp. galls on leaves of Solidago gigantea; 66. Very young galls. 67. Mature gall. Figs. 68 – 69. Rhopalomyia gina galls on leaves of Solidago juncea. 68. Gall on upper side of leaf. 69. Tail-like appendage of gall on underside of leaf.