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)

Vlada Peneva,Shesh Kumari,Stela Lazarova

doi:10.3897/zookeys.574.8037

Abstract

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.

Highlights

The Xiphinema americanum-group is a well defined natural complex of species (Lamberti et al 2000, Coomans et al 2001, He et al 2005b) with high significance to agriculture caused by the ability of several species to transmit economically important plant viruses (McFarlane et al 2002), there are controversial opinions defining the group (Archidona-Yuste et al 2016)
This was the case with several populations from the Czech Republic and Slovakia (Kumari et al 2005, 2010b) originally identified as X. pachtaicum (Tulaganov, 1938) and one population from Morocco provisionally determined as X. pachtaicum
The Xiphinema specimens examined originated from various localities in the Czech Republic (Kurdějov, Mohyla míru and Sokolnice, grapevines), Slovakia (Moča, grapevine), Bulgaria (Balgarene village, pear tree, Vinogradets vicinity, vineyard) and Morocco (Ifrane, holm oak tree)

Summary

Introduction

The Xiphinema americanum-group is a well defined natural complex of species (Lamberti et al 2000, Coomans et al 2001, He et al 2005b) with high significance to agriculture caused by the ability of several species to transmit economically important plant viruses (McFarlane et al 2002), there are controversial opinions defining the group (Archidona-Yuste et al 2016). During the last decade wide usage of DNA sequencing in Xiphinema taxonomy including this group revealed the existence of a number of cryptic species (Gutiérrez-Gutiérrez et al 2010, 2012, Archidona-Yuste et al 2016). This was the case with several populations from the Czech Republic and Slovakia (Kumari et al 2005, 2010b) originally identified as X. pachtaicum (Tulaganov, 1938) and one population from Morocco provisionally determined as X. pachtaicum. The objectives of the present study were: i) to characterise populations from the Czech Republic, Slovakia and Morocco both morphologically and genetically; ii) to sequence populations of X. pachtaicum and X. parasimile Barsi & Lamberti, 2004 from Bulgaria for comparison; iii) to clarify phylogenetic relationships of identified species using ribosomal and mithochondrial DNA

Objectives

Findings

Methods