Additional data on Iranian trichodorids (Triplonchida: Trichodoridae) and first record of a rare species, Trichodorus variabilis Roca, 1998

Abstract

Trichodorus variabilis, recovered from three separate locations in natural forests of northern Iran, was studied using morphological, morphometric and molecular data. Variation in position of the ventromedian cervical papillae (CP1 and CP2) with respect to the onchiostyle base in the resting position, and spicule characters (having or lacking striation in distal blade region and bristles in proximal blade region) were observed. Variation was also observed in the nature of the pharyngo-intestinal junction (offset to slight overlapping). The secretory-excretory pore of females also showed slight variation in placement. Molecular phylogenetic studies, using partial 28S rDNA D2-D3 sequences of three studied populations and one sequenced isolate of the species from Greece, revealed T. variabilis has variation in the sequences of this genomic fragment. The similarity percent of four sequences ranged from 96.7 to 99.7%. The species was found for the first time outside of Greece, the country from which it was originally described. A newly recovered population of T. persicus, originally described from Iran, was also included in the molecular phylogenetic analyses.

First report of Longidorus mindanaoensis Coomans, De Ley, Jimenez and De Ley, 2012 (Nematoda: Longidoridae) From a Mangrove Forest in Vietnam

“…It had a 99.6% identity to the same sequence of the type population and three different nucleotides were detected between both populations. This variation could be explained by intraspecies variation in this genomic region and is recently observed for several other longidorids and trichodorids (Pedram et al, 2017;Fouladvand et al, 2019). It had a 69.3 to 80.7% identity with sequences available in the GenBank database (154-265 different nucleotides).…”

“…2). This genomic fragment has already used in molecular phylogenetic analyses of longidorids and has successfully delimited several species belonging to cryptic complexes (Pedram et al, 2012;Gutiérrez-Gutiérrez et al, 2013;Pedram et al, 2017;Zhao et al, 2017;Fouladvand et al, 2019). Figure 2: Bayesian phylogenetic tree generated using D2-D3 expansion segments of Longidorus mindanaoensis (Coomans et al, 2012) from Vietnam using Xiphinema index (Thorne and Allen, 1950) and Xiphinema diversicaudatum (Micoletzky, 1927) (Thorne, 1939) as outgroup taxa under the GTR+G evolutionary model.…”

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

“…The newly obtained sequences of the D2-D3 of 28S rRNA gene were aligned using ClustalX 1.83 (Thompson et al, 1997) with corresponding published gene sequences (Kumari & Subbotin, 2012;Zhao et al, 2013;Heydari et al, 2014;Pedram et al, 2014Pedram et al, , 2015Pedram et al, , 2017Asghari et al, 2018;Decraemer et al, 2018;Huang et al, 2018 and others). Outgroup taxa for each dataset were chosen based on previously published data (Kumari & Subbotin, 2012;Decraemer et al, 2018).…”

Distribution of trichodorid species in mainland China with description of Trichodorus hangzhouensis sp. nov. (Nematoda, Triplonchida)

“…Previously, morphological identification alone rendered difficulties due to the mixed species complexes, phenotypic variation (such as shape of some sclerotized structures, e.g., stylet, male spicules, vagina with its sclerotized pieces), overlapping diagnostic characters and uniformity in general appearance; however, DNA-based strategies have made it possible to overcome the limitations of the morphological approach only and provided useful insights into trichodorid taxonomy (Subbotin et al 2019). In recent years several nematologists have successfully applied rRNA genes sequence (18S, 28S, and ITS) analyses for studying the phylogenetic relationships of trichodorid species (Duarte et al 2010, Zhao et al 2013, Pedram et al 2015, 2017. The importance of sequence-based studies for species identification and the lack of molecular data of known species from China has led us to compile a detailed report of trichodorids occurring in the country.…”