Two Ektaphelenchinae Paramonov, 1964 (Nematoda: Rhabditida) from Iran have tripartite stylet, with similar observations in other species.

Majid Pedram

doi:10.1371/journal.pone.0215731

Abstract

Two ektaphelenchid nematodes representing one new and one known species are illustrated and characterized using morphological and molecular data. Ektaphelenchus kanzakii n. sp. is mainly characterized by its tripartite stylet having a well visible wide lumen, encompassing a sclerotized and acute anterior part (the conus), a short and slightly tapering middle part (the conophore) that is equally sclerotized but clearly separate from the conus, and a long posterior part that is cylindrical and only weakly sclerotized (the shaft) without basal knobs or swellings. It is further characterized by 863.5 (772–926) μm long females having 23.8 (21.2–27.0) μm long total stylet, distinctly annulated cuticle, three lines in lateral field, vulva at 76.6 (75.3–80.0)%, no rectum, vestigial anus in some individuals, conical posterior body end (tail) with narrow ventrally bent tip, common males in population with two pairs of caudal papillae (the single precloacal papilla and the third caudal pair lacking), spicules with dorsally bent tip and conical tail with sharp or blunt tip. The new species is morphologically compared with close species having conical posterior body end and stylet lacking basal knobs or swellings. Iranian population of Devibursaphelenchus teratospicularis, the second studied species, is characterized by 679.5 (620–709) μm long females having 18.6 (17.5–20.0) μm long total stylet with similar structure to the previous species, subcylindrical body end with widely rounded tip, and rare males with typical spicules of this species and a pair of precloacal and a pair of caudal papillae. Molecular phylogenetic studies of the two recovered species using small and large subunit ribosomal DNA (SSU and LSU rDNA) partial sequences revealed they have close phylogenetic affinities with Ektaphelenchus obtusus in both reconstructed trees. However, species of both genera Ektaphelenchus and Devibursaphelenchus don’t form monophyletic groups in SSU and LSU trees. New observations on stylet structure of the two presently studied and some other ektaphelenchid species having available light microphotographs (LM) yielded on definition of a new term “conophore” for the middle part of the ektaphelenchid-type tripartite stylet.

Highlights

28 species are placed under the genus Ektaphelenchus Fuchs, 1937 [1] (24 in Hunt [2], plus four recently described species: E. taiwanensis Gu, Wang & Chen, 2013 [3], E. ibericus Gu, Wang, Chen & Wang, 2013 [4], E. berbericus Alvani, Mahdikhani-Moghadam, GiblinDavis & Pedram, 2016 [5] and E. oleae Miraeiz, Heydari, Adeldoost & Ye, 2017 [6], thereafter)
The same three partite stylet structure was observed for the recovered population of Devibursaphelenchus teratospicularis
A close inspecting of available light microphotographs of the species Ektaphelenchus oleae (Fig 3A, original description), E. berbericus (Fig 2B, original description), E. obtusus (Figs 9C and 11A within [36]) and Devibursaphelenchus teratospicularis (Fig 1D within [34]), revealed the aforementioned species/populations have the same stylet structure, i.e. the stylet is composed of a conus, a conophore and a shaft

Summary

Introduction

28 species are placed under the genus Ektaphelenchus Fuchs, 1937 [1] (24 in Hunt [2], plus four recently described species: E. taiwanensis Gu, Wang & Chen, 2013 [3], E. ibericus Gu, Wang, Chen & Wang, 2013 [4], E. berbericus Alvani, Mahdikhani-Moghadam, GiblinDavis & Pedram, 2016 [5] and E. oleae Miraeiz, Heydari, Adeldoost & Ye, 2017 [6], thereafter). Devibursaphelenchus Kakuliya, 1967 [7], one of the rare aphelenchoidid genera, currently includes five nominal species [8, 9] and is known in Iran with only one representative, D. kheirii Aliramaji, Pourjam, Atighi, Karegar & Pedram, 2014 [9], the last species added to the genus. The two other species belonged to one new and a known species of the respective genera Ektaphelenchus and Devibursaphelenchus and are studied and illustrated in present paper

Methods

Results

Conclusion