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Platycheirus immarginatus

 
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stuart
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Joined: 11 May 2005
Posts: 737
Location: Peterborough, UK

PostPosted: Sat May 28, 2005 5:39 pm    Post subject: Platycheirus immarginatus Reply with quote

Platycheirus immarginatus (Zetterstedt, 1849)

Identification ease/difficulty: 4

StatusSources of information
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stuart
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Joined: 11 May 2005
Posts: 737
Location: Peterborough, UK

PostPosted: Sun May 29, 2005 8:41 am    Post subject: Species account from the Provisional atlas Reply with quote

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

Platycheirus immarginatus (Zetterstedt, 1849)

Biology: The larvae feed on the aphid Trichocallis cyperi on Carex spp. in wetlands. In Britain, it is usually found in brackish marshes and saltmarsh, and Speight (1998) notes the tendency for it to be a coastal species towards the Atlantic margins of Europe. Adults fly low down amongst stands of tall vegetation have been found at the flowers of Scirpus maritimus. They are normally found by sweeping

Distribution: Very localised, but can be abundant where it occurs. This is a problematic species in that identifications made using older keys (even by experienced workers), are frequently wrong, and do not take account of recent species splits (e.g. P. occultus). Although there are many inland records, especially in the older literature, it is not at all clear whether the species genuinely occurs away from brackish coastal localities in Britain. Most identification guides (e.g. Coe, 1953; Stubbs & Falk, 1983) suggest that there are inland records, but recent (1990 onwards) records from the most experienced and reliable recorders are exclusively coastal, and it is these which have been mapped here
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stuart
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Joined: 11 May 2005
Posts: 737
Location: Peterborough, UK

PostPosted: Sun May 29, 2005 9:09 am    Post subject: Data sheet from National Review of Diptera, Falk, 1991 Reply with quote

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

PLATYCHEIRUS IMMARGINATUS (Zetterstedt) NOTABLE

DISTRIBUTION Records widely dispersed in England, Wales and Scotland.

HABITAT Mainly brackish coastal marshes, including saline marsh along tidal rivers. There are some records for fens and river margins but these need verification.

ECOLOGY Larvae probably aphidophagous. Adults recorded from May to August and are known to visit a range of flowers.

STATUS A very local but widespread species with about 25 known post 1960 sites and occasionally recorded in abundance.

THREAT The drainage of coastal wetlands for agricultural improvement and coastal development. River improvement schemes and the loss of riverside vegetation. Pollution such as agricultural run-off. Overgrazing could be detrimental and mis-management of water levels could lead to scrub invasion and other changes in vegetation.

MANAGEMENT Maintain a natural hydological regime and ensure a full succession or mosaic of vegetation types including pools, ditches and their marginal vegetation.
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