Distribution of the pill clam Pisidium langleyanum Melvill &amp Ponsonby, 1891 (Bivalvia: Sphaeriidae) in South Africa

Abstract

This article focuses on the geographical distribution and habitats of the pill clam, Pisidium langleyanum as reflected by 632 samples on record in the database of the National Freshwater Snail Collection (NFSC). The 177 different loci ( 1/16-degree squares) from which these samples were collected display a relatively continuous distribution in southern Gauteng, northeastern Free State, the central area of Mpumulanga and the western part of Lesotho. However, it is discontinuously spread through KwaZulu-Natal and the Eastern Cape, poorly represented in North West, nearly absent in the Northern and Western Cape and completely absent from Limpopo. Details of each habitat as described by collectors during surveys were statistically analysed, as well as altitude and mean annual air temperatures and rainfall for each locality. This species was reported from 10 of the 14 water-body types represented in the database, but the largest number of samples was recovered from rivers, swamps and streams.

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