Description of two Pseudaphelenchus species (Tylenchomorpha: Aphelenchoididae) associated with Asian termites and proposal of Tylaphelenchinae n. subfam.

Two newPseudaphelenchusspecies were discovered from subterranean and arboreal termites from the East Asian subtropics.Pseudaphelenchus suin. sp. isolated fromCoptotermes formosanuswas collected from Miyako Isl., Okinawa, Japan, andP. scheffrahnin. sp. was isolated fromNasutitermes takasagoensiscollected from the Kenting National Park in Taiwan. The two new species andP. vindai, previously described from Panamanian termites, are close to each other, and are not easily distinguished morphologically,i.e., these three are almost ‘cryptic species’. However, they can be distinguished based on minor morphological differences, including shape of male bursa (clearest inP. vindai, vague inP. suin. sp. and intermediate inP. scheffrahnin. sp.), male tail tip (P. suin. sp. often have a small mucron but the others do not), and in the character of the female tail (the two new species have stronger ventral curvature thanP. vindai, and further,P. suin. sp. has clear annulation at distal part, while the other species do not). Molecular phylogenetic analysis based upon near-full-length sequences of the small subunit of the ribosomal RNA gene suggested thatPseudaphelenchusandTylaphelenchusform a strongly-supported clade at the base of the family Aphelenchoididae, and thatTylaphelenchusis included inPseudaphelenchusas an inner clade. Therefore, based on their phylogenetic status and common morphological characters,e.g., small body and spherical median bulb, a subfamily, Tylaphelenchinae n. subfam. is proposed to embrace these two genera. In addition,Ruehmaphelenchus ipidicolan. comb. (= Tylaphelenchusipidicola) is proposed.