New evidence of nematode-endosymbiont bacteria coevolution based on one new and one known dagger nematode species of Xiphinema americanum-group (Nematoda, Longidoridae)

Abstract

Three populations of Xiphinema primum n. sp. and two populations of X . pachtaicum were recovered from natural forests and cultural regions of northern Iran. Both species belong to the X . americanum -group and were characterized by their morphological, morphometric and molecular data. The new species, which was recovered in three locations, belongs to the X . brevicolle -complex and is characterized by 2124–2981 μm long females with a widely rounded lip region separated from the rest of the body by a depression, 103–125 μm long odontostyle, two equally developed genital branches with endosymbiont bacteria inside the ovary, which are visible under light microscope (LM), vulva located at 51.8–58.0%, the tail is 26–37 μm long with a bluntly rounded end and four juvenile developmental stages. It was morphologically compared with nine similar species viz . X . brevicolle , X . diffusum , X . incognitum , X . himalayense , X . luci , X . parabrevicolle , X . paramonovi , X . parataylori and X . taylori . The second species, X . pachtaicum , was recovered in two geographically distant points close to city of Amol. Molecular phylogenetic studies of the new species were performed using partial sequences of the D2-D3 expansion segments of the large subunit ribosomal RNA gene (LSU rDNA D2-D3), the internal-transcribed spacer rDNA (ITS = ITS1+5.8S+ITS2), and the mitochondrial cytochrome c oxidase I gene ( COI mtDNA) regions. The Iranian population of X . pachtaicum was also phylogenetically studied based upon its LSU rDNA D2-D3 sequences. Both species were also inspected for their putative endosymbiont bacteria. Candidatus Xiphinematobacter sp. was detected from two examined populations of the new species, whereas the second endosymbiont bacterium, detected from three examined isolates of X . pachtaicum , was related to the plant and fungal endosymbionts of the family Burkholderiaceae. The phylogenetic analyses of the two endosymbiont bacteria were performed using partial sequences of 16S rDNA. In cophylogenetic analyses, significant levels of cophylogenetic signal were observed using both LSU rDNA D2-D3 and COI mtDNA markers of the host nematodes and 16S rDNA marker of the endosymbiont bacteria.

Description of Longidorella (Saevadorella) caspica n. sp. (Dorylaimida: Nordiidae) from north Iran

“…The sequences were aligned using the Q-INS-i algorithm of the online version of MAFFT version 7 (http://mafft.cbrc.jp/alignment/ server/) (Katoh and Standley, 2013). The poorly aligned positions and divergent regions were eliminated using the online version of Gblocks 0.91b (Castresana, 2000) using all three less stringent options (Mobasseri et al, 2019;Panahandeh et al, 2018). The model of base substitution was selected using MrModeltest 2 (Nylander, 2004).…”

“…The new species was morphologically compared with seven nominal species under the subgenus viz. Longidorella (Saevadorella) arenicola (Vinciguerra and Zullini, 1980), L. (S.) cuspidata (Andrássy, 1964;Jairajpuri and Hooper, 1969), L. (S.) magna (Loof, 1971), L. (S.) perplexa (Siddiqi, 2007), L. (S.) saadi (Siddiqi, 2007), L. (S.) saeva (Siddiqi, 1982) and L. (S.) tharensis (Nasira et al, 2010) as follow. From Longidorella (Saevadorella) arenicola by a longer body of female (788-874 vs 630-750 μ m), shorter odontostyle (32-33 vs 40-42 μ m), greater b (3.5-3.8 vs 2.7-3.3) value, pore-like vulval opening (vs transverse slit), less ventromedian male copulatory supplements (five to seven vs nine) with the last supplement distantly placed to the spicules' head (vs close).…”

Three species of Xiphinema americanum-group complex (Nematoda: Longidoridae), from Lorestan province, Iran

“…Ten species of Xiphinema have been reported from Iran. They are X. americanum, X. bacaniboia, X. brevicollum, X. himalayense, X. oxycaudatum, X. pachtaicum, X. pacfi cum and X. rivesi (Ghaderi et al, 2018), X. simile (Naghavi et al, 2018) and X. primum (Mobasseri, et al, 2020). In the present nematological survey on longidorids in Khorramabad county, Lorestan province, southwest of Iran, three nematode species of the genus Xiphinema namely X. oxycaudatum, X. pachtaicum and X. plesiopachtaicum were collected from several natural environments and were identifi ed based on morphological and morphometrics characters and out of this three nematode species, X. plesiopachtaicum is a new record for nematode fauna of Iran.…”

“…Ten species of Xiphinema have been reported from Iran. They are X. americanum , X. bacaniboia , X. brevicollum , X. himalayense , X. oxycaudatum , X. pachtaicum , X. pacficum and X. rivesi ( Ghaderi et al, 2018 ), X. simile ( Naghavi et al, 2018 ) and X. primum ( Mobasseri, et al, 2020 ). In the present nematological survey on longidorids in Khorramabad county, Lorestan province, southwest of Iran, three nematode species of the genus Xiphinema namely…”

Data of an Iranian Population of L. proximus Sturhan & Argo, 1983, with taxonomic revision of L. israelensis Peneva, Orion, Shlevin, Bar-Eyal & Brown, 1998 (Nematoda: Longidoridae) and Proposal for a New Synonymy

“…The history of the reported Longidorus (Mikoletzky, 1922) species in Iran is given by Gharibzadeh et al (2018). Some recent studies in Iran have focused on the molecular taxonomy of longidorids in Iran (Jahanshahi Afshar, 2019;Jahanshahi Afshar et al, 2019;Mirzaie Fouladvand et al, 2019;Mobasseri et al, 2019). During the present study, a population of Longidorus was recovered from a wheat-potato field in Hamadan province and was studied using morphological and molecular criteria.…”