Tylenchorhynchus zeae Sethi and Swarup, 1968

Alvani, Somaye, Mahdikhani-Moghadam, Esmat, Rouhani, Hamid & Mohammadi, Abbas, 2017, Morphological and molecular characterization and phylogenetic position of a new record, Tylenchorhynchus zeae, and some known species of Telotylenchidae Siddiqi, 1960 and Merliniidae Siddiqi, 1971 from Iran, Turkish Journal of Zoology 41 (2), pp. 227-236 : 229-231

Tylenchorhynchus zeae Sethi and Swarup, 1968 ( Figures 2 and 3 )

Measurements: See Table 3.

Female: Body cylindrical, slightly curved ventrally when killed by heat. Body clearly annulated, annuli 1.3 µm wide at midbody. Lateral field with four incisures. Lip region continuous with body contour, head with four annuli. Stylet with rounded anteriorly flattened to laterally directed knobs. Dorsal gland opening 2.5–3 µm posterior to the stylet base. Median bulb large, isthmus surrounded by the nerve ring. Reproductive system didelphic, amphidelphic with both genital branches equally developed, anterior branch 133.5–220 µm long, posterior one 97–170 µm long, vulva slightly protuberant. Ovaries straight, spermatheca functional, rounded. Phasmid openings large, located laterally at the longitudinal middle of the tail. Tail subcylindrical including 12–16 annuli and tip without annuli.

Male: General morphology similar to that of female but slightly more slender. Testis single, anteriorly outstretched.

Spicules paired, 20–22 µm long, gubernaculum distinct, rod-shaped with slightly curved anteriorly and about 7–8 µm long. Bursa extends anteriorly to the cloaca with 11 annuli and posteriorly envelops the tail tip.

Molecular information (D2-D3 segment of 28S rRNA) of Tylenchorhynchus zeae : The partial sequence of the 28S rRNA (D2-D3 segment) for T. zeae yielded

698-bp nucleotides. The DNA sequence was submitted to GenBank with accession number KM068058. Bayesian analysis showed T. zeae from Iran to be related to other T. zeae sequences (KJ461563, KJ461564, and KJ461566). NBLAST search based on 28S sequences from the Iranian population of T. zeae (KM068058) attributed 99% similarities with other T. zeae sequences deposited

ALVANI et al. / Turk J Zool in GenBank. A multiple alignment of 650 bp of the 28S gene for three Tylenchorhynchus species indicated that 648 sites were conserved and two were variable. In the phylogenetic tree reconstructed based on 28S sequences, T. zeae (KM068058) formed a monophyletic group with three additional T. zeae sequences with 100% bootstrap support ( Figure 4 ). The mean interspecific distance (using the K2P model) based on 28S sequences was 0.25.

Figures

Figure 2. Tylenchorhynchus zeae: anterior end of the female (A), head with stylet (B), lateral lines (C), vulva with ovary (D), tail terminus in female (E), tail terminus with bursa in male (F), phasmid (G), and spicule (H).

Figure 3. Tylenchorhynchus zeae: anterior end of the female (A) and male (B), head with stylet (C), shape of the female body (D) and male (E), vulva with ovary (F), lateral lines (G), tail with bursa in male (H), and tail of female (I–K).

Figure 4. Phylogenetic relationships among selected species of the order Tylenchida: Bayesian 50% majority rule consensus tree from two runs as inferred from analysis of the D2D3 of 28S rRNA gene sequence alignment under the GTR + I + G model. New sequences are indicated in bold (Table 1).