Agromyza isolata Malloch,

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, Zootaxa 4479 (1), pp. 1-156: 11

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Agromyza isolata Malloch


Agromyza isolata Malloch 

( Figs. 2View FIGURES 1–6. 1, 70–71View FIGURES 63–74)

Material examined. VERMONT: Chittenden Co.  , South Burlington, Winooski Gorge,, em  . 15.vii.2014, C.S. Eiseman, ex Populus balsamifera  , #CSE1176, CNC384839–384841 (3♂); Williston, Mud Pond, 28.viii.2016, em. 18–19.ix.2016, C.S. Eiseman, ex Populus balsamifera  , #CSE3000, CNC654500–654504 (2♂ 3♀).

Hosts. Salicaceae  : Populus balsamifera  L., P. deltoides W. Bartram ex Marshall, P.  × jackii Sarg., P. trichocarpa Torr. & A.Gray  ex. Hook., Salix bebbiana Sarg.  (leaf mines only), S. lucida Muhl.  ( Spencer 1969; Spencer & Steyskal 1986). Spencer (1969) caught an adult female on P. tremuloides  .

Leaf mine. ( Figs. 70–71View FIGURES 63–74) “Large irregular blackish blotch, with several larvae normally feeding together” ( Spencer 1969). In our first collection of this species, the mines were not distinguished in the field from those of Agromyza albitarsis  (see Comments). In our second collection, six very small, brown, irregular mines were found near the center of a leaf blade ( Fig. 70View FIGURES 63–74). These expanded to large, irregularly lobed, pale greenish-brown blotches that partially coalesced, none of them quite reaching the leaf margins when complete ( Fig. 71View FIGURES 63–74). The frass was in scattered black grains and irregular particles.

Puparium. ( Fig. 2View FIGURES 1–6. 1) Yellow to yellowish-brown, 1.9–2.0 mm by 0.9–1.1 mm; formed outside the mine.

Distribution. USA: CA, CO, MN (leaf mines only), PA, *VT, WA; Canada: AB, ON, QC, SK.

Comments. In 2014 we collected mines of this species on Populus balsamifera  along with similar mines that yielded adults of Agromyza albitarsis  . At the time of collection, the mines were all assumed to represent the same fly species, and those of A. isolata  were not photographed. When the larvae had emerged, the differences in the puparia of the two species were obvious; those of A. albitarsis  were substantially larger and were reddish-brown rather than yellow ( Fig. 2View FIGURES 1–6. 1). The leaf from which we reared A. isolata  in 2016 also contained a single larva of what we believe was A. albitarsis  , forming a large, greenish mine along the leaf margin. It formed a puparium that was substantially larger than those of A. isolata  , but no adult emerged.