73.335 Diarsia florida (Fen Square-spot)
fw: 15-17mm (Waring & Townsend), ws: 30-38mm (MBGBI9); Jun-Jul; various herbaceous plants; fens and acid bogs in East Anglia, N.England and Wales. Status as a separate species (from D.rubi) uncertain
ID: Forewing ground colour pale to dark pinkish-brown with variable banding and clouding with reddish-brown or dark brown. Similar to D.mendica (Ingrailed Clay) but D.rubi/florida can usually be recognised by a smoother more evenly curved postmedian line; that of D.medica being more scalloped and irregularly curved. Distinguishing D.mendica from D.rubi/florida may require genital examination and this is covered by the Difficult Species Guide.
The status of D.florida (Fen Square-spot) is uncertain. It is regarded as a separate species in the RES Checklist, but there are no diagnostic external characters, it has identical genitalia to D.rubi and hybridisation of the two forms produces fertile offspring. It is said to average larger, paler and brighter than D.rubi and has a single generation late June-July, between the two generations of D.rubi. It occurs in E.Anglia, N.England and Wales. Scottish populations of D.rubi/florida are univoltine Jun-Jul and are currently accepted as D.rubi, but may be better treated as D.florida.
The status of D.florida (Fen Square-spot) is uncertain. It is regarded as a separate species in the RES Checklist, but there are no diagnostic external characters, it has identical genitalia to D.rubi and hybridisation of the two forms produces fertile offspring. It is said to average larger, paler and brighter than D.rubi and has a single generation late June-July, between the two generations of D.rubi. It occurs in E.Anglia, N.England and Wales. Scottish populations of D.rubi/florida are univoltine Jun-Jul and are currently accepted as D.rubi, but may be better treated as D.florida.
§1 Buttermere, Cumbria; 20/06/2014
All images © Chris Lewis
All images © Chris Lewis
Page published 04/02/2017 (§1)