Descriptions of two new and one known species of Parkellus Jairajpuri, Tahseen and Choi, 2001 (Nematoda: Mononchidae) and their phylogenetic position among Mononchida

Abstract

Two new species of Parkellus (Jairajpuri et al., 2001) from Vietnam and a population of Parkellus zschokkei (Ahmad and Jairajpuri, 2010;Menzel, 1913) from Ukraine are described, illustrated and their phylogenetic position among the Mononchida is presented. The molecular data (18S and 28S rDNA) are given for the three investigated species -first time for the genus Parkellus. Parkellus hagiangensis sp. nov. is characterized by a medium-sized buccal cavity, posterior position of the dorsal tooth located below the beginning of the pharynx, males having the ventromedian cuticular pores above and below the excretory pore, short spicules with conical proximal part; females with very faint pars refringens vaginae and small teardropshaped pieces, short pars distalis vaginae, the presence of small ventromedian vulval papillae. Parkellus tuyenquangensis sp. nov. is characterized by a medium-sized buccal cavity, posterior position of the dorsal tooth located above the beginning of the pharynx, males having the ventromedian cuticular pores above and below the excretory pore, medium-sized spicules with a cylindrical proximal part, very short lateral guiding pieces, females with very strongly sclerotized pars refringens vaginae, medium size teardrop-shaped pieces, short pars distalis vaginae thickened at the junction with pars refringens vaginae. The newly described species are morphologically most similar to P. parkus and P. zschokkei. An identification key to Parkellus species is presented.

Description of Paramylonchulus iranicus sp. n. (Nematoda: Mononchida) from Iran

“…The consensus tree inferred using our SSU sequence alignment (Figure 5) indicated that the Mylonchulus species stand close to Paramylonchulus. The same result was obtained by previous studies (Van Megen et al 2009;Olia et al 2008;Shokoohi et al 2013;Koohkan et al 2015;Vu 2021;Vu et al 2021;Shokoohi and Moyo 2022). The present results show that the new species is well separated from other Mylonchulus species.…”

Twenty Years after De Ley and Blaxter—How Far Did We Progress in Understanding the Phylogeny of the Phylum Nematoda?

“…The phylogeny of Mononchina is well represented, with members from all three families listed in De Ley and Blaxter [ 2 , 3 ] being included in phylogenetic analyses. Only Mylonchulidae is unequivocally resolved as monophyletic, while Mononchidae and Anatonchidae are usually paraphyletic or polyphyletic (D14 in Figure 2 b), depending on the particularities of the analysis [ 38 , 39 ]. The families Iotonchidae and Cobbonchidae, not included in De Ley and Blaxter [ 2 , 3 ] but accepted in subsequent classifications [ 40 ], have not been included in molecular phylogenetic analyses yet.…”