Heterodera circeae sp. n. and H. scutellariae sp. n. (Tylenchida: Heteroderidae) from Germany, with notes on the goettingiana group

Abstract

Abstract Two species of cyst-forming nematodes belonging to the goettingiana group are described from woodland in Germany. Heterodera circeae sp. n., parasitising Circaea lutetiana (Onagraceae), most closely resembles H. carotae and H. cruciferae, from which it differs by larger cysts (430-720 μm) and longer fenestral length (27-54 μm) and rounded stylet knobs of the second-stage juveniles. Heterodera scutellariae sp. n., found on the labiate Scutellaria galericulata (Lamiaceae), is distinguished from the other species of this group by shorter body (358-437 μm) and tail (41-53 μm) of the second-stage juveniles. The ITS-rDNA sequences of the new species are very similar and differ from each other by only a few nucleotides. The phylogenetic position of the new species within the group is presented based on analyses of molecular data. A revised diagnosis of the goettingiana group is proposed. The species of the group have lemon-shaped, ambifenestrate and abullate (small bullae occasionally present) cysts with egg sac, long vulval slit (> 35 μm), thin vulval bridge, low semifenestrae (average fenestral length 30-45 μm), and weak underbridge. Second-stage juveniles are characterised by body length > 400 μm, tail length > 45 μ m, hyaline tail portion > 20 μm, stylet length > 20 μm, lateral field with four incisures and small phasmids. All known species of the goettingiana group exclusively parasitise dicotyledonous plants.