Re-description of three species of the genus Sectonema Thorne, 1930 (Nematoda: Dorylaimida: Aporcelaimidae) originally studied by E. Altherr.

Three species of the genus Sectonema, namely S. demani, S. heynsi and S. macrospiculum, originally described by E. Altherr, are re-described on the basis of type material. Detailed descriptions, morphometrics and illustrations, including line drawings and/or LM pictures, diagnoses and remarks about their identity and later reports are provided for each species. Sectonema demani is characterized by its 6.78-7.24 mm long body, lip region 27-28 µm broad, mural tooth 19-20 µm long at its ventral side, pharyngeal expansion 834-875 µm long or 68-69% of total neck length, uterus a simple tube-like structure 2.1-2.2 times the corresponding body diameter, V = 49-52, tail short and rounded conoid (51-55 µm, c = 123-143, c' = 0.7-0.8), and male unknown. Sectonema heynsi is distinguished by its body 6.45 mm long, lip region 28 μm broad, circumoral area bearing cilia- or seta-like structures, mural tooth-like structure 20 μm long, pharyngeal expansion 856 μm long or 68% of total neck length, uterus a tube-like structure ?1.7 times the corresponding body diameter, V = 50, tail short and rounded to conoid (54 μm, c = 120, c' = 0.7), and male unknown. And S. macrospiculum is characterized by its 4.07-5.06 mm long body, lip region 27-28 μm broad, ventral side of the odontostyle 15 μm long, pharyngeal expansion 555-640 μm long or 67-68% of total neck length, uterus a simple tube-like structure 1.9-2.1 times the corresponding body diameter, V = 53, female tail short and convex conoid with rounded terminus (62 μm, c = 82, c' = 0.7), male tail more conoid than that of female and with the ventral side visibly more straight (58 μm, c = 71, c' = 0.8), spicules 107 μm long, and eight irregularly spaced ventromedian supplements bearing hiatus.