Melanostoma dubium

[stuart]

Melanostoma dubium (Zetterstedt, 1837)

Identification ease/difficulty: 4

Status

• Notable in Falk (1991)

Sources of information

• Page 117 in Stubbs & Falk (1983)
• Map here and page 89 in Ball & Morris (2000)
• Page 169 in Stubbs & Falk (2002)

[stuart]

Species account from Provisional atlas of British hoverflies, Ball & Morris, 2000.

Melanostoma dubium (Zetterstedt, 1838) Melanostoma mellinum var. dubium Verrall nec Zetterstedt in Coe (1953)

Biology: The larvae remain unknown, but other members of this genus are suspected to be general predators in leaf litter. Adults are found in mountainous areas, and recent work by MacGowan & Rotheray (quoted in Stubbs, 1996) suggests that there is an altitudinal cline between M. mellinum at lower altitude and M. dubium higher up. This might suggest that these are ecotypes of the same species, but opinion among European workers is divided

Distribution: This is an upland species which occurs above about 460m in northern and western Britain

[stuart]

Datasheet from the Review of Scarce and Threatened Diptera, Falk (1991).

MELANOSTOMA DUBIUM (Zetterstedt) NOTABLE

DISTRIBUTION Mainly recorded from the Scottish Highlands (Argyllshire, Perthshire, Westerness, Ross-shire) and the Pennines (Yorkshire, Durham).

HABITAT Montane and upland areas with most records for altitudes between 460 and 915 m and characteristically on boggy ground near small streams. It has also been taken at lower ground near a lake.

ECOLOGY Larvae probably aphidophagous though details unknown. Adults recorded from June to August and may be found feeding on a range of flowers, especially tormentil Potentilla erecta and buttercups.

STATUS It has only been regarded as a distinct species in Britain over the last few years but recent evidence suggests it could be locally frequent in montane areas.

THREAT The drainage of upland bog areas for improved pasture and afforestation of lower slopes on mountains. Skiing could be a problem in some areas leading to soil erosion and a loss of vegetation.

MANAGEMENT Maintain the natural hydrology and vegetation communities of upland bogs and streams and ensure their freedom from excessive disturbance.