Sectonema caobangense sp. n. from Vietnam (Nematoda, Dorylaimida, Aporcelaimidae).

Sectonema caobangense sp. n. from evergreen forest soil in Vietnam is described, including scanning electron micrograph (SEM) observations and D2-D3 LSU rDNA analysis. The new species is characterized by its 3.12 to 5.80 mm long body, lip region offset by deep constriction and 21 to 23 µm broad, mural tooth 13 to 14 µm long at its ventral side, 940 to 1,112 µm long neck, pharyngeal expansion occupying 61% to 69% of total neck length, uterus a long simple tube-like structure 292 to 363 µm long or 2.7 to 2.9 times the corresponding body diameter, pars refringens vaginae well developed, V = 48 to 56, short (36-51 µm, c = 77-132, c' = 0.5-0.8) and rounded tail, 87 to 99 µm long spicules, and four or five irregularly spaced ventromedian supplements bearing hiatus. Sectonema caobangense sp. n. differs from the typical pattern of Sectonema in the nature of the stomatal protrusible structure, bearing a mural tooth attached to the ventral side of the stoma. Molecular data obtained and the derived evolutionary trees support a close phylogenetic relationship with other Sectonema species.

A Third New Species of Aporcelinus (Dorylaimida, Aporcelaimidae) from Vietnam, with the First SEM Study of a Representative of the Genus.

A new species, the third one from Vietnam, of the genus Aporcelinus is described from natural areas. Aporcelinus falcicaudatus sp. n. is characterized by its 1.28 to 1.63 mm long body, lip region offset by weak constriction and 16 to 18 µm broad, odontostyle 18 to 21 µm at its ventral side, neck 354 to 406 µm long, uterus tripartite and 61 to 95 µm long, V = 50 to 55, tail strongly recurved dorsad and conical (23-31 µm, c = 43-58, c' = 0.7-0.9) with finely rounded tip, and male absent. Scanning electron microscope (SEM) study, the first of a representative of the genus, shows a lip region pattern significantly different from that observed in the typical aporcelaimid taxa.