Phytomyza sp. 4 (Fig. 220) Material examined. COLORADO: Fremont Co., Bear Creek, Forest Rd. 101, off of 49 Rd., 7.vii.2015, em. by 31.iii.2016, C.S. Eiseman, ex Symphoricarpos orbiculatus, #CSE2297, CNC 634819 (1♀). Host. Caprifoliaceae: Symphoricarpos orbiculatus Moench. Leaf mine. (Fig. 220) Greenish-white to pale brown; an irregular linear-blotch, varying from essentially linear throughout to having no evident linear portion when complete. Frass diffuse and indistinct in some examples, in others forming a meandering, broken line or deposited in irregular particles. Puparium. Brown; formed within the mine. Comments. Our single female specimen cannot be identified to species. Four Nearctic Phytomyza species are recorded from Symphoricarpos, three of them covered by Griffiths (1974a) and one described as new here. Mines of P. palmeri, found in Oklahoma, are essentially linear throughout, with frass consistently placed in lines of discrete, closely spaced grains, quite distinct in appearance from the Colorado mines. The mine of P. symphoricarpi (Griffiths), known from Alberta and California, is based on the midrib, which was not the case for any of the Colorado mines. Phytomyza caprifoliae Spencer, known only from Alberta, forms a “gradually widening linear-blotch” with the frass “deposited as fine particles, mostly separated by less than 1 mm ”; this description more or less falls within the range of variation observed in the Colorado mines. The mine of P. fricki (Griffiths), discussed above, is said to be initially stellate, and this was clearly evident in the P. fricki mines we collected in Idaho, but not in those we collected in Wyoming, possibly because the beginning was obscured in the finished mines. In most of the Colorado mines the beginning was visible, and it was never stellate, nor did any of the mines branch later. Otherwise, they were not markedly different from our Wyoming examples of P. fricki. More rearings from Symphoricarpos will be needed to determine the number of species involved and the full range of variation in their mines.

Published as part of Eiseman, Charles S. & Lonsdale, Owen, 2018, New state and host records for Agromyzidae (Diptera) in the United States, with the description of thirty new species, pp. 1-156 in Zootaxa 4479 (1) on page 93, DOI: 10.11646/zootaxa.4479.1.1, http://zenodo.org/record/1452913