Seinura hyrcania, Adeldoost, Yaser, Heydari, Ramin, Miraiez, Esmail, Jalalinasab, Parisa & Asghari, Ramezan, 2016

Adeldoost, Yaser, Heydari, Ramin, Miraiez, Esmail, Jalalinasab, Parisa & Asghari, Ramezan, 2016, Description of two new species of Seinura Fuchs, 1931 (Nematoda: Aphelenchoididae) from Iran, Zootaxa 4168 (3), pp. 541-556 : 549-552

Seinura hyrcania n. sp.

( Figs 5 & 6 )

Measurements. See Table 1 .

Description. (Based on Gorgan isolate). Female. Medium sized nematodes 0.43–0.6 mm long, slightly ventrally curved after heat relaxation. Cuticle ca 1.0 µm thick with fine transverse striae. Lateral fields with three incisures. Lip region separated from body contour by a constriction, 4–4.5 µm high, and 7.5–8.5 µm wide. Cephalic region with six labial sectors of equal width. Stylet 18–24 µm long, lacking basal swellings and with conus occupying ca 38–45% of its total length. Stylet tip oriented ventrally. Procorpus cylindrical, connected to elongate rectangular metacorpus, with anterior granular part occupying 35–40% of its total length, and the posterior part is moderately muscular encircling metacorpus valve. Excretory pore with some variation in position and anterior to metacorpus valve level. The pharyngo-intestinal junction not visible. Pharyngeal glands well developed, overlapping intestine dorsally, 5–8 times as long as body diameter at level of metacorpus. Hemizonid 19–32 µm posterior to the excretory pore, inconspicuous in some specimens. Nerve ring located below metacorpus and surrounds both intestine and pharynx. Ovary outstretched comprising oocytes arranged in a single row and anteriorly directed, spermatheca mostly invisible, crustaformeria not conspicuous, uterus with thick wall, vagina oblique, vulva a simple slit in ventral view, without a flap in lateral and ventral views, at 288–431 µm from anterior end, post-uterine sac short, 13–30% of vulva-anus length and lacking sperm. Intestine granulate and ending in a functional rectum and distinct anus. Tail conical, uniformly narrowing to a filiform terminus 3.6–8 times body wide at the anus region.

Male. Not found.

Diagnosis and relationships. The female of S. hyrcania n. sp. is characterized by having a distinctly offset cephalic region, total stylet length of 18–24 µm, three incisures in lateral field, excretory pore opening anterior to level of metacorpus valve, a relatively short post-uterine sac occupying 13–30% vulva-anus distance, conical tail with filiform tip and length 3.6–8 times body diameter at the anus. According to the presence of a post-uterine sac, absence of basal swellings on the stylet and shape of the tail, the new species is close to S. obscura , S. onondagensis , S. oswegoensis and S. persica n. sp. Compared with S. obscura , the new species differs by position of excretory pore (anterior to vs posterior to metacorpus base), anterior position of vulva (V ratio= 71 (66–74) vs 77 (75–79)) and presence of a functional anus and rectum vs indistinct. The new species can be distinguished from S. onondagensis by having an offset cephalic region vs continuous, shorter tail length of 65 (51–82) vs (88–97) µm and differing number of lateral lines (3 vs 4). Compared to S. oswegoensis (data from Grewal et al., 1991), probably the closest species, the new species differs by having a shorter post-uterine sac 19 (12–25) vs 53 (45–70) µm in length, and arrangement of oocytes (in one column vs 3–4 columns). Compared to S. persica n. sp. the new species differs by the different number of lateral lines (3 vs 4), shape of the tail terminus (filiform vs pointed), and shorter post-uterine sac (19 (12–26) vs 54.8 (50–60) µm).

Specimens from Guilan differ from the type population from Gorgan in having a shorter and more slender body, smaller stylet, and shorter tail. These differences are attributable to intraspecific variability, as confirmed by molecular analyses.

Type host and locality. The type specimens were recovered from wood and bark samples of a dead beech tree ( Fagus orientalis L.) in Gorgan , Golestan Province (GPS coordinates: N 36° 73', E 54° 28'), northern Iran .

Other locality. This species was also found in a wood sample from a dead pine tree ( Pinus sp.) in Siahkal region in Guilan Province (GPS coordinates: N 37° 64', E 49° 51'), northern Iran.

Etymology. The species epithet “ hyrcania ” refers to the ancient Greek name of Gorgan, the city of origin of this species.

Type material. Holotype female, slide ASH 001 together with four paratype specimens (Slides ASH 001 , ASH 002 ) deposited in the Nematode Collection of the Department of Plant Protection, Karaj, Iran . Additional paratypes distributed as follows: three females at the nematode collection of Royal Belgian Institute of Natural Sciences , Brussels , three females at the National Nematode Collection of the Department of Nematology , Iranian Research Institute of Plant protection, Tehran, Iran .

Figures

FIGURE 5. Line drawings of Seinura hyrcania n. sp. A: Female anterior region; B: Female anterior end; C: Female posterior end; D: Female entire body; E: Female posterior region; F, G & H: Variation in position of excretory pore.

FIGURE 6. Photomicrographs of Seinura hyrcania n. sp. A: Female anterior region; B-D: Female Anterior end; B: Stylet; C: Offset head, D: Lip morphology; E & F: Variation in position of excretory pore, arrows show excretory pore and hemizonid; G: three lateral lines; H: Female posterior region; I: Female posterior region showing post-uterine sac; J: Female posterior end showing rectum and anus. (Scale bars: A & H = 20 µm; B, C, D, E, F, G, I & J = 10 µm).