Two new species of Ungellidae and Homungellidae (Drilonematoidea; Rhabditida) from Vietnamese earthworms and the phylogenetic links of these families.

摘要

Two new species of the families Ungellidae and Homungellidae (Drilonematoidea) are described from the coelomic cavity of Vietnamese earthworms. Siconema ovispicatum sp. nov. (from Amynthas robustus collected in Cuc Phuong Natural Park) is characterized by fused cephalic hooks, egg-shells covered with widely set acute pyramid-shaped spikes and polar caps comprised of tightly set small rounded or pointed tubercles around 2-3 micro m high. Perodira minuta sp. nov. (collected from Pheretima hawayana in Ba Vi National Park) is characterized by its small size; membrane on a head end; cephalic sensilla in two circles; pin-shaped sperm in male gonad; tapered not coiled male tail; lack of caudal bursa/membrane; symmetrically disposed caudal organs. According to the phylogenetic analysis based on 18S rDNA partial sequences of described nematodes both genera Siconema (Ungellidae) and Perodira (Homungellidae) are related to free-living cephalobid genera.