Parodontophora huashanensis Li & Guo, 2016

Hong, Jung-Ho, Kim, Kichoon & Lee, Seunghan Lee and Kanghyun, 2024, Four unrecorded species of free-living nematodes from the sublittoral zone in the East Sea, Korea, Journal of Species Research 13 (2), pp. 147-158 : 152-153

Parodontophora huashanensis Li & Guo, 2016

( Fig. 2 , Table 2)

Locality. The specimens were collected from the subtidal region off the coast of Gijang in the southern part of the East Sea, Korea (35°16 ʹ 0.0 ʺ N, 129°16 ʹ 50.0 ʺ E) at a depth of 16 m, within clay sediment .

Material. Five males ( MABIK NA00158032 , MABIK NA00158075 - MABIK NA00158078 ) and three females ( MABIK NA00158079 - MABIK NA00158080 ) were collected by Jung-Ho Hong off the coast of Gijang on 30 April 2023, from Research Vessel Haeyanghwnangkyung 3 .

Measurements. See Table 2 for detailed measurements and morphometric ratios.

Description. Males ( Fig. 2 , Table 2). Body cylindrical, gradually tapering towards the tail end, about 1216-1345 μm long and 40-44 μm wide at maximum body diameter. Cuticle with faint longitudinal striation. Lip region rounded with six outer labial papillae. Cephalic setae 3-4 μm long located 4 μm from anterior end. Opisthocephalic setae 2-3 μm long, arranged as two subdorsal groups of two longitudinally arranged setae and two single subventral setae, i.e. (2D-1V)2. Somatic setae scattered, about 2 μm long. Buccal cavity (25-29 μm long, 4-5 μm wide) in two parts, anterior part with six teeth and the cylindrical posterior part with conspicuous sclerotized parallel walls. Open-looped shape amphids situated at 2 μm from anterior body apex, shorter dorsal branch (12-13 μm) about half as long as the ventral branch (18-21 μm). Amphid opens to dorsal branch. Posterior end of amphid near half the base of stoma. Pharynx starting at base of stoma, muscular, and gradually broadens to base. Cardia small, roundedconoid. Nerve ring at 53-69% of pharynx length. Renette cell slightly behind the base of pharynx, long oval shape, 42-53% of pharynx length. Excretory pore indistinct near cephalic setae at anterior part of buccal cavity. Tail length 125-148 μm, conical anteriorly and cylindrical posteriorly, pointed terminal end without terminal setae. Three caudal glands open to spinneret. Testes outstretched, opposed. Anterior testis to right and posterior testis to left of intestine. Vas deferens well-developed. Spicules paired, arched with double-cephalated proximal end, 32-35 μm long along arch. Gubernaculum with dorsal-caudally directed apophysis 12-14 μm long, with middle of its ventral side thickened. 5-6 small tubular precloacal supplements present.

Females ( Fig. 2 , Table 2). Similar to male. Reproductive system amphidelphic, ovaries outstretched. Vulva situated slightly anterior to mid-body at 48.9-49.7% of body of length.

Remarks. Parodontophora huoshanensis Li & Guo, 2016 is characterized by comparatively short cephalic setae, the posterior end of the amphid positioned far from the base of the buccal cavity, opisthocephalic setae arrayed as (2D-1V)2, the excretory pore located near the cephalic setae at the anterior part of the buccal cavity, Renette cell occupying 34-60% of the pharynx length, and the presence of six small tubular precloacal supplements. Our specimens from the East Sea, Korea, closely resemble the original description by Li & Guo in 2016. However, they exhibit slight differences, being smaller in both body width (40-44 μm compared to the original description of 42-72 μm) and body length (1190-1345 μm compared to the original description of 1235-1408 μm). We interpret this variation as intraspecific diversity.

Figures

Fig. 2. Parodontophora huoshanensis Li & Guo, 2016, from the East Sea, Korea. A, Male head; B, Female head, pharynx, vulva, anus; C, Male copulatory apparatus and tail. Scale bars: 20μm (A, C) and 200μm (B).