Phytomyza tiarellae Griffiths

Eiseman, Charles S., Lonsdale, Owen, Linden, John Van Der, Feldman, Tracy S. & Palmer, Michael W., 2021, Thirteen new species of Agromyzidae (Diptera) from the United States, with new host and distribution records for 32 additional species, Zootaxa 4931 (1), pp. 1-68 : 38-39

Phytomyza tiarellae Griffiths

Material examined. WASHINGTON: Thurston Co., Lacey, Chehalis Western Trail / S. 45th Ave. , 11.iii.2018, em.?, E. Stansbury, ex Tolmiea menziesii , # CSE4608 , CNC1135594–1135595 (1♁ 1♀) ; Olympia, Watershed Park , 15.iii.2018, em.?, E. Stansbury, ex Tolmiea menziesii , # CSE4607 , CNC1135586 (1♀) ; Olympia, Watershed Park , 11.v.2018, em. 29.v.2018, ex Tellima grandiflora, E. Stansbury , # CSE5038 , CNC934532–934534 (2♁ 1♀) ; Tolmie State Park , 23.v.2018, em. 8.vi.2018, E. Stansbury, ex Tiarella trifoliata , # CSE4610 , CNC1144078 (1♁) ; same but em. 11.vi.2018, # CSE4609 , CNC1135583 (1♁).

Photographed mine. BRITISH COLUMBIA: Vancouver Island, Sooke , 10.viii.2019, Mews, Tiarella trifoliata , iNat 30890584 .

Hosts. Saxifragaceae : Heuchera micrantha Douglas , Tellima grandiflora (Pursh) Douglas ex Lindl. ( Spencer 1981) , Tiarella trifoliata L., Tolmiea menziesii (Pursh) Torr. & A.Gray ( Griffiths 1972) .

Leaf mine. Upper-surface; entirely linear, “appearing white in incident light, up to 20-25 cm long, about 2 mm wide terminally; faeces scattered as discrete particles (mostly separated by over 1 mm), or forming short “threads” (Fadenstucke) in terminal part of mine” ( Griffiths 1972).

Puparium. Brown or white, with darker strip on ventral surface; formed within the leaf, on the lower surface, with its anterior spiracles projecting ventrally through the lower epidermis ( Griffiths 1972).

Phenology and voltinism. In Alaska, larvae and puparia collected in late August yielded one adult in early September and one the following spring. From this, Griffiths (1972) concluded that this species is at least partly multivoltine. The Washington material collected in March likely involved puparia that had overwintered, with the next generation represented by the mines collected in late May, which yielded adults in early to mid-June.

Distribution. USA: AK ( Griffiths 1972), CA ( Spencer 1981), [OR] (see below), WA; [ Canada: BC].

Comments. This species was reported from Washington previously, but based only on a female specimen ( Winkler et al. 2009). The California records of Spencer (1981) are based on a male and female reared from Heuchera micrantha in Santa Cruz Co., along with leaf mines found on Tellima grandiflora in Marin Co. Griffiths (1972) also reported the latter host based only on leaf mines, and the CSE5038 specimens are the first actually to be reared from Tellima . Eiseman & Lonsdale (2018) reported as “ Phytomyza sp. 7” a female reared from Tiarella trifoliata in Oregon that could not be confidently identified as P. tiarellae , but this specimen does fit within the known range of P. tiarellae and we thus have not seen evidence that there is another species west of the Rocky Mountains whose leaf mine could be mistaken for that of P. tiarellae .