046 Elachista albidella

ELACHISTIDAE

38.046 Elachista albidella (Cottongrass Sedge-miner)

ws: 9-10mm; Jun-Aug; common cottongrass (Eriophorum angustifolium), slender tufted-sedge (Carex acuta), greater pond-sedge (Carex riparia), common spike-rush (Eleocharis palustris), deergrass (Trochophorum cespitosum); common on bogs and heaths throughout Britain.
Synonym: Biselachista albidella MBGBI3

Elachista albidella §4 male

ID: In MBGBI3 this species is keyed from: forewing with markings both paler and darker than ground colour. However, this species is variable and may appear as pale with darker markings - from where one cannot arrive at the correct species using the MBGBI3 key. It appears that only E.albidella, E.utonella & E.eleochariella show an elongate dark mark in the fold near the dorsum, just before 1/2.
ID best confirmed by genital examination:
Male genitalia: paired gnathos > the former Biselachista species; pointed extension at apex of valva > E.albidella. No other species has a valva quite so rounded on the dorsal edge near the apex.

Variation
Dissection
Male genitalia
Female genitalia

§1 Sutton Fen, Norfolk; 12/08/2010
§2 Sutton Fen, Norfolk; male; 13/08/2009
§3 New Forest, Hampshire; 05/06/2012; male; fw 4.2mm
§4 Foulden Common, Norfolk; 14/08/2016; male
§5 Foulden Common, Norfolk; 14/08/2016; male; fw 4.1mm
§6 Surlingham, Norfolk; 07/07/2018; male; fw 4.2mm
§7 Foulness, Essex; 08/07/2023; female; fw 5.5mm
§8 Duddon Mosses, Cumbria; 18/06/2023; male; fw 4.0mm
All images © Chris Lewis