Tuesday, July 25, 2017

Trocheta subviridis: informal literature review

There isn't a vast body of literature on my foolishly stamped on but new best friend, T. subviridis. Gray (1922) caught my eye for several reasons. It refers to the finding of the leech in an allotment, in South Shields, of all places. This would appear to be the most northerly example at that time. The allotment exhibits similarities to mine: "As there is no drainage system, the land has been trenched to the depth of one and a half spits, and a well sunk in the clay in one corner, into which an endeavour is made to collect water in winter", though my endeavours at drainage have been more successful with the Council's drain operating as an overflow to my pond, also "sunk in the clay".  

A population was studied in a stream in Bristol by Hartley (1962). The stream was subject to sewage contamination, and this chimed with the allotment in Gray, which was treated with "night soil". (I can say that in 1922 most houses in south Tyneside did not have flush lavatories, and that a household's excrement was removed at night through a door beneath the lavatory in the house's back yard, in a terraced row of houses' back lane. It was then distributed for agricultural and allotment use). Hartley suggests the leeches have a lifespan of 4-5 years, and that the adults spend most of their time away from the stream. Reynolds (1996) also notes the leech's residence in drains and sewers. 

Warwick (1960) refers tantalizingly to an "unpublished occurence" of T. subviridis in Glasgow

There is nothing else, so far as my limited searches go. If and when I find and photograph any more specimens, I have to hope that any researchers interested in T. subviridis find their way here...

Gray, R. H. (1922). The occurrence of a Leech (Trocheta subviridis) in an Allotment. Parasitology, 14(3-4), 320-321.

Hartley, J. C. (1962). The life history of Trocheta subviridis Dutrochet. The Journal of Animal Ecology, 519-524.
Reynolds, J. D., & Tenison, M. (1996). Trocheta subviridis Dutrochet, a Leech New to Eastern Ireland. The Irish Naturalists' Journal, 25(8), 302-302.
Warwick, T. and Mann, K. H. 1960 The freshwater leeches of Scotland. Ann. Mag. nat. Hist. Ser. (13) 3, 25-34.