Description of Stegelletina tessellata sp. nov. (Rhabditida, Cephalobidae) from Tabernas Desert, Spain

Summary A new species of the genus Stegelletina , S. tessellata sp. nov., is described from the Tabernas Desert in the southern Iberian Peninsula. The new species is distinguished by the following: a body 0.26-0.34 mm long with habitus sigmoid or almost straight after fixation, the cuticle divided into blocks of 2-3 μ m of thickness, lateral fields having three longitudinal incisures, a lip region with lips having three rounded and one acute process, primary axils with one triangular axillar guard process (or two U-shaped refringent structures) and secondary axils lacking axillar guard processes (or one U-shaped refringent structure), amphids rounded, labial probolae Y-shaped with stipe (base) and furca (prongs) smooth, stoma cephaloboid with well-sclerotised rhabdia, pharynx cephaloboid with pharyngeal corpus 2.5-4.3 times isthmus length, nerve ring surrounding isthmus, excretory pore at isthmus level, deirids at the level of the basal bulb, the female reproductive system monodelphic-prodelphic with a well-developed spermatheca and post-vulval uterine sac 0.3-0.5 times the corresponding body diam. long, rectum 0.9-1.2 times anal body diam., tail conoid bearing a tuberculate mucron, phasmids at 30-45% of tail length, and the male unknown. Additionally, the species of the genus Stegelletina are listed and illustrated, including a key to species identification.