Bitylenchus parvus ( Allen, 1955 ) Jairajpuri, 1982

Azizi, Kourosh, Eskandari, Ali, Karegar, Akbar, Ghaderi, Reza, Elsen, Sven Van Den, Holterman, Martijn & Helder, Johannes, 2022, Analyses of morphological and molecular characteristics of Telotylenchinae from Iran point at the validity of the genera Bitylenchus and Sauertylenchus, Zootaxa 5169 (5), pp. 425-446 : 430-432

Bitylenchus parvus ( Allen, 1955) Jairajpuri, 1982

Syn: Tylenchorhynchus parvus Allen, 1955

Bitylenchus parvus ( Allen, 1955) Siddiqi, 1986

( Figure 2 , Table 3 )

Description

Female

Body straight to curved ventrally after heat fixation. Cuticle annuli 0.9–1 μm wide at mid-body. Lateral field consisting of four longitudinal incisures, often areolated. Lip region continuous to slightly offset, 7–7.7 μm wide at base, 4.0–4.1 μm high, and bearing six or seven transverse annuli. Cephalic framework slightly sclerotized, outer margins extending two or three body annuli posteriorly. Stylet strong, basal knobs laterally directed; the conus almost half of the total stylet length. Dorsal pharyngeal gland orifice located 2.2–2.3 μm behind stylet knobs. Median pharyngeal bulb oval, 10–11 μm wide; basal bulb pyriform. Hemizonid 2–4 annuli anterior to secretoryexcretory pore. Reproductive system didelphic, amphidelphic; spermatheca rounded, with globular sperm. Vagina 12–13 μm long, almost 50–60% of the vulval body width. Intestinal fasciculi present in the intestine and inside the post rectal sac which extends into almost the entire tail cavity. Tail cylindrical, finely striated or sometimes smooth terminus, bearing 60–67 annuli on ventral side. Hyaline region of tail terminus 5–6 μm thick. Phasmids located 25–30 μm posterior to anus, located in the posterior half of the tail.

Male

Not found.

REMARKS

Compared to the original description of B. parvus Allen (1955) , the Iranian population has a lower c' ratio (11.5–12.1 vs 13–16). No other difference in morphological or morphometric diagnostic characters was found. Although this population shows similarity to Sauertylenchus maximus , it can be distinguished from it by a smaller body and stylet (680–800 vs 940–1062, and 17.7–19.6 vs 20–24 μm), and the number of tail annuli (60–67 vs 25– 45). This species was recovered from the rhizosphere of alfalfa ( Medicago sativa ) in Zanjan and Qazvin provinces during the present study.

Figures

FIG. 2. Photomicrographs of Bitylenchus parvus. Females (A–N). A: Pharynx; B–D: Head and stylet; E: Terminal bulb; F & G: Lateral field; H: Vulva; I: Spermatheca; J: Entire body; K–N: Tail. (Scale bars: A = 20 μm; J: = 100 μm; B–I & K–N = 10 μm); [ph = phasmid; s = spermatheca].