Rhopalomyia clarkei Felt 1907

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 : 10-11

Rhopalomyia clarkei Felt 1907

Rhopalomyia clarkei Felt 1907c: 18 .

Adult: Antenna with 17–19 flagellomeres in male, 15–17 in female; necks of male flagellomeres III–VII 0.57–0.77 times as long as nodes, necks of female flagellomeres 0.19–0.23 times as long as nodes. Palpus 1-segmented, fusiform to triangular, tapered, setose and setulose. Wing length 2.4–2.6 mm in male, 2.2–2.5 mm in female. Male terminalia ( Fig. 14 ): gonocoxite bulbous, setose and setulose, with setose mediobasal lobe; gonocoxal apodeme anteriorly divided into two very short lobes; gonostylus wide, hardly narrowed toward apex, setose and setulose, with small, brush-like tooth; aedeagus narrow, truncate; hypoproct entire, truncate, setose and setulose; cerci separated by a triangular notch, setose and setulose. Female abdomen (Fig. 30): tergite 7 rectangular, weakly sclerotized along anterior and posterior margins, with two anterior trichoid sensilla, a group of setae posteriorly, and groups of setae mesolaterally; tergite 8 wide Y-shaped, arms about third length of shaft, each with anterior trichoid sensillum; ovipositor 6.3 times as long as tergite 7.

Pupa ( Figs. 44–45 ): Antennal bases developed into abruptly tapering horns, pointed anteriorly. Posterior margins of antennal bases rounded V-shaped in frontal view. Frons without projections, ridges or lateral projections, posterior edge widely rounded.

Type material: Rhopalomyia clarkei Felt. Holotype: female, USA, NH, Tamworth, 6/X/1907, C.H. Clarke, ex S. rugosa, Felt # a1634, deposited in Felt Collection.

Other material examined: 1 male, USA, MA, Magnolia, unspecified date, C.H. Clarke, ex. S. rugosa, Felt # a1634, deposited in Felt Collection; 2 males, 2 females, 2 pupae, USA, NY, Fall Creek and Freese Rd., 8–19/VIII/1987, M.V. McEvoy, ex S. rugosa ; 3 pupae, USA, PA, Bucknell University Chillisquaque Creek Natural Area, 16/VI/2005, N. Dorchin, ex. S. rugosa ; 2 females, USA, VA, Boyce, 8/X/2008, M. Wise, ex. S. altissima . Felt (1915) mentioned that galls of this species were also collected by him from Solidago canadensis (the name he used for S. altissima ) in Asheville, NC on 29/IX/1906, as well as by T.D. Jarvis in Ontario, Canada on 20/IX/1907.

Hosts: Solidago rugosa , S. altissima .

Gall and biology: The galls are small, conical and single-chambered, usually occurring on the lower side of leaves but occasionally on the upper side of leaves and on stems ( Figs.62–65 ). When on leaves, the gall is always attached to either a major or minor vein ( Figs. 62–64 ). Each gall contains a single white larva. Galls on S. rugosa are 2.5–6.0 mm long and 0.7–1.2 mm wide at widest part, tapering toward apex, green to yellowish green, and covered by short, whitish hairs. Very young galls are sometimes accompanied by a tuft of hair at their base, almost as long as the gall itself. The species is multivoltine and galls can be found from late May to early October. It is heavily parasitized and adults are extremely difficult to rear. In September and October 2008, similar galls were found on Solidago altissima in Boyce, Virginia by M. Wise ( Fig. 65 ). Only two females were reared from these galls, but based on their morphology and that of the galls, we concluded they belong to R. clarkei , confirming Felt’s report (1915) of this species from S. altissima .

Remarks: The tiny, inconspicuous galls of R. clarkei were originally described only from Solidago rugosa , but we found very similar galls on three other hosts: R. altissima ( Fig. 65 ), R. gigantea ( Fig. 67 ), and R. juncea ( Fig. 68 ). We initially assumed that galls from all these hosts belong to R. clarkei , but a recent molecular analysis (Dorchin et al., in prep.) indicate that the populations from S. gigantea and S. juncea represent distinct species, with the former being the closest relative of R. clarkei . Samples from S. altissima were not analyzed. The population from S. gigantea is discussed below under R. inquisitor and R. sp., whereas the population from S. juncea is described here as a new species – R. gina . Rhopalomyia clarkei is morphologically very similar to R. inquisitor , but differs from R. gina in having stouter male gonopods and in lacking a longitudinal groove along the antennal horns and lateral projections of the eyes in the pupa.

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

FIGURES 40 – 47. Pupal heads. 40. Rhopalomyia anthophila, ventral. 41. Rhopalomyia anthophila, lateral. 42. Rhopalomyia capitata, ventral. 43. Rhopalomyia capitata, lateral. 44. Rhopalomyia clarkei, ventral. 45. Rhopalomyia clarkei, lateral. 46. Rhopalomyia gina, ventral. 47. Rhopalomyia gina, lateral. Scale bars = 200 μm

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.