Redescription of Rhabditis maupasi Seurat in Maupas, 1919 (Rhabditida: Rhabditidae) from northwest Iran

Summary Rhabditis maupasi is re-described and reviewed based on morphological, morphometric, and molecular (D2-D3 expansion segment of the rDNA 28S) analysis collected from northwest Iran. The species is characterised by having a 1.1-1.9 mm long body, lateral fields with three incisures, the lip region offset by a depression, 12-15 μm wide, with six globular lips, the stoma rhabditoid, 14-20 μm long, with distinct cheilo-, gymno- and stegostom; cheilostom slightly cuticularised, gymno-promesostegostom a short tube with well-cuticularised walls, metastegostom with glottoid apparatus bearing small teeth, stomatal or pharyngeal collar covering 40-60% of stoma; pharynx well developed, the pharyngeal corpus consisting of a more or less cylindrical procorpus and swollen metacorpus (median bulb), basal bulb ovoid to pyriform, with grinder and narrow haustrulum, excretory pore at basal bulb level; vulva a transverse slit with protruding lips, the female tail conical-elongated (65-75 μm, c = 16-26, c′ = 2.0-2.5), the male tail conoid, ventrally arcuate (29-34 μm, c = 22-41, c′ = 0.7-1.0); spicules free, with pointed end and dagger-shaped, 61-72 μm long, bursa pseudopeloderan, and with eight pairs of genital papillae plus the phasmid, and gubernaculum 34-36 μm long. Furthermore, its relationship with four closely related species of the genus is discussed. A molecular phylogenetic study using a partial sequence of large subunit ribosomal DNA fragments revealed that R. maupasi forms a clade with R. terricola, recorded previously from Iran.