Morphological and molecular characterisation, and phylogenetic position of X. browni sp. n., X. penevi sp. n. and two known species of Xiphinema americanum-group (Nematoda, Longidoridae)

Using ribosomal (18S, ITS1, ITS2, D2-D3 expansion segments of 28S rDNA) and mitochondrial (partial cox1 and nad4) DNA markers in a study of several populations of Xiphinema americanum-group from Europe and Morocco, two cryptic species Xiphinema browni sp. n. (formerly reported as Xiphinema pachtaicum) and Xiphinema penevi sp. n. were revealed. The species are described, illustrated and their phylogenetic relationships discussed. The first species is most similar to Xiphinema parasimile and is a member of Xiphinema simile species complex. The phylogenetic reconstructions inferred from three molecular markers (18S, D2-D3 28S rDNA and cox1) showed that Xiphinema penevi sp. n. is part of Xiphinema pachtaicum-subgroup and is closely related to Xiphinema incertum, Xiphinema pachtaicum, Xiphinema parapachydermum, Xiphinema plesiopachtaicum, Xiphinema astaregiense and Xiphinema pachydermum. Also, a separate "Xiphinema simile-subgroup", outside the Xiphinema pachtaicum-subgroup and so far consisting only of the parthenogenetic species Xiphinema simile, Xiphinema parasimile, Xiphinema browni sp. n. and probably Xiphinema vallense was formed. New primers for amplification and sequencing of part of the nad4 mitochondrial gene were designed and used.