A new dagger nematode, Xiphinema poasense n. sp. (Nematoda: Longidoridae), from Costa Rica

Abstract

A new dagger nematode, Xiphinema poasense n. sp., is described and illustrated from three populations extracted from soil associated with a combined plantation of Eucalyptus sp., Cupressus sp. and Pennisetum sp. and wild plants from a tropical pre-montane forest in Costa Rica. The new dagger nematode is characterised by a moderate body size 2612 (2416-3042) μm long, a rounded lip region 15.0 (13.5-16.5) μm broad, separated from the body contour by a shallow depression, amphidial fovea large, stirrup-shaped, a very long odontostyle (175 (164-188) μm), stylet guiding ring located 167 (136-181) μm from anterior end, vulva situated anterior to mid-body (36-40%), anterior genital branch complete but strongly reduced, without uterine differentiation, female tail short, hemispherical to convex-conoid with a c′ ratio = 0.7 (0.6-0.8) and bearing two pairs of caudal pores, and male absent. Integrative diagnosis was completed with molecular data using D2-D3 expansion segments of 28S rRNA, ITS1 region, partial 18S-rRNA and the partial mitochondrial gene cytochrome c oxidase subunit 1 (coxI). The phylogenetic relationships based on D2-D3 segments of this species with other Xiphinema spp. of the X. non-americanum group indicated that X. poasense n. sp. clustered with other species with a reduced anterior genital branch from the morphospecies Group 2, viz., X. costaricense and X. krugi. However, the phylogeny of coxI and partial 18S rRNA gene revealed that the new species did not cluster with Xiphinema species having the anterior genital branch absent or reduced (i.e., morphospecies Groups 1 and 2, respectively).