The Xiphinema americanum-group in Portugal with descriptions of four new species (Nematoda, Dorylaimida).

A study of the specific composition of the Xiphinema americanum-group in Portugal, including Madeira and Azores, indicated the occurrence of twelve species, seven known species (X. diffusum, X. duriense, X. madeirense, X. pachtaicum, X. rivesi, X. santos and X. pachydermum) and five undescribed species, four of which are described as new and are named: X. brevisicum, X. longistilum, X. mesostilum and X. microstilum. The fifth is not named because of the scarsity of material. X. pachydermum, X. brevisicum, X. longistilum, X. mesostilum and X. microstilum which all have common or abundant males constitute a new sub-group within the X. americanum-group. X. diffusum and X. rivesi are reported far the first lime from Portugal. Comments are made on the geographical distribution of all these species in Portugal. A dichotomous key is proposed far the identification of the named species within the X. americanum-group occurring in Portugal.