Peromyia trimera ( Edwards, 1938 )

Jaschhof, Mathias & Jaschhof, Catrin, 2017, Mycophagous gall midges (Diptera, Cecidomyiidae: Lestremiinae, Micromyinae, Winnertziinae, Porricondylinae): first records in Sweden and descriptions of closely related new species from elsewhere, Zootaxa 4226 (4), pp. 546-570 : 554-555

Peromyia trimera ( Edwards, 1938) stat. rev.

Fig. 4A–B

Peromyia trimera was described by Edwards (1938) as a Joannisia and subsequently treated as a distinct species of Peromyia by Mamaev (1963), Kleesattel (1979), and Berest (1994). MJ, in his revision of Holarctic ‛Lestremiinae’ ( Jaschhof 1998), regarded P. trimera as synonymous with P. ramosa ( Edwards, 1938) . The problem with P. trimera is that Edwards’s (1938) description of this species was based on a single male with distorted genitalia, including collapsed gonostyli (see Jaschhof 1998). The same specimen was apparently undisturbed when Edwards (1938: fig. 25j) made the genital drawing of it. Four males of a Peromyia found in Sweden fit exactly the original description of P. trimera , causing us here to revive this species from the synonymy with P. ramosa . Male genitalic characters to distinguish the two species are as follows. In P. ramosa , the gonostyli are massive, often slightly broadened apically and covered with dense, long setae medioapically; the tegmen is blunt-ended; and the gonocoxae have a large asetose extension anteriorly ( Jaschhof 1998: fig. 215ād). In P. trimera , the gonostyli are much more slender, parallel-sided, and equipped with sparse, short setae; the tegmen is pointed apically; and the asetose anterior extension of the gonocoxae is smaller ( Fig. 4A). As another distinction, there are 2 rows of postocular bristles in P. ramosa but only 1 row in P. trimera . Other non-genitalic characters (see Edwards 1938) appear to be of no merit for differentiating between the two species.

Previous distribution. United Kingdom. Occurrence in Sweden: Öland, Uppland.

Specimens studied. SWEDEN: male (CEC250), Öland, Mörbylånga , Gamla Skogsby , scrubby meadow (“diversity meadow”), 18 Aug.–18 Sep. 2015, Malaise trap, M. & C. Jaschhof ; 2 males (CEC251–252), Öland, Borgholm, Rönnerum-Abbantorp NR, swampy mixed deciduous forest, 17 June–21 Aug. 2015, Malaise trap, M. & C. Jaschhof; male (CEC153), Uppland, Uppsala, Ekdalen NR, thin old oak woodland, 1̄ 15 Sep. 2003, Malaise trap, SMTP (trap 27, collection event 470).