Published online by Cambridge University Press: 28 April 2016
Spirobolbolaimus undulatus sp. nov. is described in intertidal sandy sediment from the East China Sea. The new species is characterized by six jointed outer labial setae much thicker and longer than the four slender cephalic setae, anterior and posterior pharynx bulbs, sclerotized multispiral amphid fovea, eight longitudinal rows of postamphideal setae, gubernaculum apophysis and many precloacal supplements. The new species differs distinctly from the type species Spirobolbolaimus bathyalis in the presence (vs absence) of jointed outer labial setae, eight additional small teeth, gubernaculum apophysis and many precloacal supplements and eight (vs six) rows of postamphideal setae. It differs from the other known congener Spirobolbolaimus boucherorum in the jointed outer labial setae (vs setae with smooth outline), three main teeth with eight additional small teeth (vs only three main teeth) and many distinct precloacal supplements (vs seven tiny papillate ones). We emend the diagnosis of the genus Spirobolbolaimus based on the description. Microlaimus pecticauda and Microlaimus spirifer possess two opposed reflexed ovaries, and thus are transferred from the family Microlaimidae to Molgolaimus of the family Desmodoridae: Molgolaimus pecticauda comb. nov. and Molgolaimus spirifer comb. nov.