Description of Xiphinema ficusi sp. n. (Nematoda: Longidoridae) and molecular characterisation of some Xiphinema species from Mexico

In 2018-2022, during nematological surveys in several Mexican states, a new species, Xiphinema ficusi sp. n., two known species, X. basiri and X. luci, and four unidentified Xiphinema species, Xiphinema sp. A, sp. B, sp. C, and sp. D, were collected and characterised. Xiphinema ficusi sp. n. was found in a tropical forest in the La Mancha Ecological Reserve of the Ecology Institute of Jalapa, Veracruz state. The new species is characterised by a body length of 2.82-3.79 mm, slightly offset lip region, odontostyle 93-105 μm long, guiding ring at 51-96 μm from anterior end, an elongate conical tail 41-50 μm long with digitate terminus, didelphic-amphidelphic reproductive system, with both gonads equally developed without Z differentiation in females. Males have one pair of adanal and four ventromedial supplements. The seven Xiphinema species were molecularly characterised and the phylogenetic relationships of these species with other representatives of this genus were reconstructed using the D2-D3 expansion segments of 28S rRNA and COI gene sequences. Molecular analysis revealed the presence of a parasitic oomycete of the genus Lagenidium in X. ficusi sp. n. and endosymbiotic bacteria of the genus Candidatus Xiphinematobacter in X. luci and Xiphinema sp. D. belonging to the Xiphinema americanum group. It has been suggested that valleys surrounded by ridges of Sierra Madre Mountains in Mexico might be one of the world centres of diversity for the genus Xiphinema.