Description of Myolaimus mycophilus Slos & Bert sp. n. (Rhabditida: Myolaimidae)

Myolaimus mycophilus Slos & Bert sp. n. was isolated from mushrooms from different locations in Belgium and cultured on nutrient agar seeded with Escherichia coli OP50. Myolaimus mycophilus sp. n. is characterised by a unique combination of the following characters: adults with lateral fields not differentiated, buccal cavity triangular, cheilostom anisomorphic, female with a post-vulval uterine sac as long as the corresponding body diam., wrinkled eggshell, male with seven pairs of genital papillae, cloacal aperture covered by a trapezoidal cloacal flap and with a single ventral papilla at its base. The new species and M. goodeyorum Andrassy, 1984 were molecularly characterised by sequencing the 18S and D2-D3 28S expansion segments of rDNA. Phylogenetic relationships were reconstructed based on concatenated analyses and the phylogenetic placement of Myolaimus, an intriguing genus within the Rhabditida, is discussed.