Description of Atetylenchus minor n. sp. (Tylenchina: Tylenchidae) and data on two other species of the family

Abstract

Three species of the family Tylenchidae, including one new and two known species, are described and illustrated. Atetylenchus minor n. sp. is characterised by its short body length of 633 (558-691) μm, MB = 45 (41-46), lateral field with four crenate incisures, stylet 12.0 (11.5-12.5) μm long, without distinct basal knobs but with swollen arms of the shaft at its base, V = 56.3 (53.7-59.3), absence of lateral vulval membranes, and conical tail 57 (51-62) μm long with a rounded tip. Morphological differences of the new species with four known species of the genus, namely A. abulbosus, A. graminus, A. amiri and A. metaporus, are discussed. Molecular phylogenetic studies of the new species using 1089 bp partial sequences of 18S rDNA revealed that the new species formed a clade with an unpublished species assigned to Psilenchus in Bayesian inference (BI) with low Bayesian posterior probability (BPP). This clade forms a sister clade to a major clade containing two species of Psilenchus and several belonolaim species and genera. The same result was achieved using maximum likelihood (ML) analysis. Morphological and molecular phylogenetic studies were also performed on two other species, Malenchus labiatus and Neothada cancellata, using 28S rDNA D2-D3 sequences. In the inferred Bayesian tree, M. labiatus formed a clade with other species of Malenchus with 28S information with maximal support (1.00 BPP), while N. cancellata formed a clade with Boleodorinae, again with maximal (1.00) BPP.