Length 2.5 to 4 mm.  Brachypterous (short-winged) and macropterous (long-winged) form occur.  A brown planthopper, with a broad pale zone down the central part of the pronotum and scutellum.  Females cannot be identifed with certainty; males can be separated by examination of internal genitalia. 

Muellerianella fairmairei or M extrusa

males

Males can be identified by microscopic examination of genitalia.  Photographs of a specimen from top down will support ID

Damp grasslands/ditches etc. with Tufted Hair-grass (Deschampsia cespitosa).

Local (ref.: UK checklist on British Bugs website)

Rarely recorded

https://www.britishbugs.org.uk/homoptera/Delphacidae/Muellerianella_brevipennis.html

R Biedermann & R Niedringhaus (2009). The Plant- and Leafhoppers of Germany. WABV