Seven new species of Trichodorus (Diphtherophorina, Trichodoridae) from Spain, an apparent centre of speciation

Abstract

During a survey for Trichodoridae in cultivated and natural environments, mainly from southern Spain, 7 new Trichodorus species were found. Four of them, T. andalusicus n. sp., T. asturanus n. sp., T. silvestris n. sp. and T. parasilvestris n. sp., belong to the T. lusitanicus morpho-species group characterised in the male by the slightly ventrally curved spicules with a mid-blade constriction with bristles, and in the female by well developed, rounded triangular to quadrangular, vaginal sclerotised pieces. They were mainly differentiated based upon differences in body length, onchiostyle length, spicule shape and number of ventromedian cervical papillae in the male, and size and shape of the vaginal sclerotised pieces in the female. The presence of the T. lusitanicus morpho-species group with 8 species, apparently endemic to the Iberian Peninsula, could point to a recent speciation event. Additionally, 3 new species, T. onubensis n. sp., T. iliplaensis n. sp. and T. paragiennensis n. sp., more closely resembling the morpho-species group of T. sparsus, to which the Spanish species T. giennensis also belongs, were identified. They were differentiated based on body length, length of onchiostyle and position of the secretory-excretory pore and, in the male, by length and shape of the spicules and number of ventromedian cervical papillae and in the female by the vaginal sclerotised pieces. Molecular support to differentiate the new species using the D2-D3 expansion segments of 28S rDNA is also provided. In addition, a new population of T. variabilis from Greece was studied as well as T. lusitanicus type specimens, and a population of T. giennensis and T. lusitanicus were also sequenced.

Unravelling the Biodiversity and Molecular Phylogeny of Needle Nematodes of the Genus Longidorus (Nematoda: Longidoridae) in Olive and a Description of Six New Species

“…To confirm the correlation of the results obtained by conventional morphological approaches and new molecular methods is important for the proper understanding of the evolution of the genus Longidorus . The close relationship of the morpho-species groups detected in this and previous studies in Spain was also supported by molecular data (most of the species described were in the same clade), an observation that points to the Iberian Peninsula as a possible center of recent speciation [ 19 ], as it was suggested for other genera such as Xiphinema [ 5 , 19 , 22 , 28 ], Trichodorus [ 95 ] or Rotylenchus species [ 11 ].…”

Molecular diversity of bacterial endosymbionts associated with dagger nematodes of the genus Xiphinema (Nematoda: Longidoridae) reveals a high degree of phylogenetic congruence with their host

“…G' was detected in X. americanum s.s., X. pachtaicum and X. simile; Vandekerckhove et al 2000;Lazarova et al 2016). Our study has been performed using a combination of integrative identification techniques (such as barcoding and morphology) because of the difficulty of species identification in this group (Palomares-Rius et al 2008De Luca et al 2009;Decraemer et al 2013;Guti errez-Guti errez et al 2013Archidona-Yuste et al 2016). This procedure of nematode host identification is unknown from other studies of endosymbionts that have published sequences and deposited them in GenBank (Lazarova et al 2016).…”

Molecular characterisation of some stubby root nematodes (Nematoda: Trichodoridae) from the USA and other countries

“…Recently, other apparent centres of speciation and diversification of Trichodoridae were found in the Iberian Peninsula and Irano-Anatolian region. At present, Spain contains the highest number of Trichodorus species per country (15 species) (Decraemer et al, 2013) followed by Iran with nine Trichodorus species recorded (Pedram et al, 2015;Asghari et al, 2018). However, we have to take into account that the recently differentiated species (e.g., from Iran, Spain) are based on a combined molecular and morphological approach.…”

“…The molecular data clearly clarified the comparative morphological study, e.g., with the interpretation of intra-vs interspecific variation, but, on the other hand, morphology and morphometrics help molecular research to interpret the results when dealing with the co-occurrence of several species. The more recent integrated approach leads to the discovery and description of new cryptic species and to redefine formerly described species with a wide range in diagnostic characters as species complexes (Decraemer et al, 2013(Decraemer et al, , 2018. This more holistic approach, also taking geographic distribution into account, provides a better insight into the relationships at genus level.…”