Characteristics of Helicotylenchus crassatus Anderson, 1973 from Central Europe in the context of similarities to H. digonicus Perry in Perry, Darling & Thorne, 1959 (Nematoda: Hoplolaimidae).

Abstract

Originally, Helicotylenchus crassatus was described by Anderson in 1973 as most similar to Helicotylenchus digonicus. Reports generated over the years question the validity of the two species, as their morphometry and most of the morphological features overlap. Additionally, the molecular data revealed the representatives of H. crassatus cluster with one of the two main lineages of the polyphyletic H. digonicus. So far, H. crassatus has neither been reported from Poland nor from other parts of Europe, while H. digonicus has been recognized as a commonly occurring species in Poland and associated with many plants. The studies of three Helicotylenchus populations from Poland, initially identified as H. cf. digonicus revealed their high molecular and morphological resemblance to the recently characterized populations of H. crassatus from Canada. Therefore, this work extends the characteristics of H. crassatus, expands its occurrence to the European continent and discusses it in the context of the similarities with H. digonicus, with which it is often confused.