Cryptic speciation in the nematode family Longidoridae from South America: description of Xiphinema cryptocostaricense sp. nov. from Colombia and notes on X. seinhorsti

Abstract

The genus Xiphinema Cobb, 1913 belongs to the family Longidoridae and consists of approximatelly 280 described species of plant-root ectoparasites. They occur on all continents except Antarctica and many species are important pests of crops, harming plants either by direct parasiting or by vectoring of nepoviruses. Due to their economic importance, several species were subjected to regulations aimed to limit their global spread. Moreover, the use of molecular techniques allowed to confirm the occurrence of cryptic species within the genus. In this paper we describe Xiphinema cryptocostaricense sp. nov., which constitutes the first instance of cryptic speciation within the family Longidoridae from South America. In terms of morphology this species is characterised by the body measuring 2.00–2.35 mm; lip region detached from the body outline only by a shallow constriction; odontostyle 129–135 µm long; V = 34.0–36.6; anterior branch of the genital tract largely reduced; tail short, almost hemispherical; lack of males and presence of four juvenile stages. This species is also characterised using molecular markers D2-D3 expansion domains of 28S rRNA, ITS1 rRNA and partial cytochrome oxidase c subunit 1 gene sequences. Based on morphology, this species is indistinguishable from X. costaricense Lamberti and Tarjan (Nematologia Mediterranea, 2, 1–11 1974). Additionally, a nomenclature remark is given- the name X. cryptocostaricense sp. nov. has been created by adding prefix ‘crypto’ to an already existing name of species. The advanatage of this approach is that it immediately points to which species it is cryptic to. Finally, new data regarding the second species, X. seinhorsti are given, including a first report of this species outside the place of its original description, data on molecular markers and morphology, including the first description of the J1 and J2 stages.