According to Fjellberg (1998), Pseudachorutes parvulus reaches 1.0 mm in length. Species of Pseudachorutes with pointed setae on the abdomen and tibiotarsi and post-antennal organ with less than 11 lobes are separated by examining the chaetotaxy. However, the Pseudachorutes parvulus and Pseudachorutes subcrassus of Fjellberg (1998) may not the same species as specimens labelled with these names in the NHML collection (the main differences are the presence/absence of setae on abd5). In view of the confusion over identification, I have decided for the moment to put all Pseudachorutes with pointed setae on the abdomen, and tibiotarsi and post antennal organ with less than 11 lobes, in the Pseudachorutes subcrassus 'group'. Gama (1964) published an important paper on Pseudachorutes in which differences in chaetotaxy (primarily on abd5) were used to separate the species. However, British specimens are very difficult to assign to Gama's species due to individual variation in the arrangement of setae. The confusion can only be resolved by detailed analysis of fresh material.
     The dots on this map are literature records for
Pseudachorutes parvulus.

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