Redescription of Macrolaimus somniorum Andrássy, 1984 (Rhabditida, Panagrolaimidae) from a coastal dune in the southeast of the Iberian Peninsula

Summary Macrolaimus somniorum is described from coastal sand dunes in the southeast of the Iberian Peninsula. The new species is distinguished by having body 0.77-0.94 mm long with habitus sigmoid or almost straight after fixation, cuticle finely annulated, lateral fields with three longitudinal incisures, lip region with lips having seta-like labial papillae almost apical and directed forward, stoma with well-sclerotised rhabdia, cheilostom longer than gymnostom, pharynx cephaloboid with pharyngeal corpus 1.5-2.1 times isthmus length, nerve ring at the beginning of isthmus, excretory pore at nerve ring level, deirids at isthmus level, female reproductive system panagrolaimoid with post-vulval uterine sac 0.5-0.7 times the corresponding body diam. long, tail of both sexes conical, slightly curved ventrally and ending in a curved dorsad harpoon-like mucron at tail tip, spicules 32-38 μ m with hook-shaped manubrium and curved ventrad lamina, and gubernaculum 12-15 μ m. Additionally, the species of the genus Macrolaimus are listed and updated, including an updated key to species identification.