Vasostoma brevispicula Huang & Wu, 2011

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 : 155-157

Vasostoma brevispicula Huang & Wu, 2011

( Fig. 4 , Table 4)

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

Material. Four males ( MABIK NA00158040 , MABIK NA00158081 - MABIK NA00158083 ) and two females ( MABIK NA00158084 - MABIK NA00158085 ) were collected by Jung-Ho Hong on the coast of Gijang on 30 April 2023, aboard the Research Vessel Haeyanghwnangkyung 3 .

Measurements. See Table 4 for detailed measurements and morphometric ratios.

Description. Males ( Fig. 4 , Table 4). Body cylindrical, slender, gradually tapering toward both extremities. Cuticle with transverse rows of dots, no lateral differentiation. Somatic setae (about 2 μm long) arranged randomly along the whole body. Tail conico-cylindrical. Three crowns of anterior sensilla: six inner labial papillae, six outer labial papillae and four short cephalic setae(3 μm long). Amphidial fovea (8-9 μm wide) large, 7-9 μm behind anterior end, situated behind cephalic setae, circular spiral form. Fovea spiral coiled ventrally, about 2.5 turns. Buccal cavity composed with small cup-shaped anterior portion (about 2 μm deep) and sclerotized cylindrical posterior portion (11-12 μm deep) with three teeth. Pharynx long (188-202 μm) and slender, cylindrical with long pyriform bulb (20-25 μm, cbd 30-33 μm). Nerve ring located at 86-94 μm (44.6-47.2%) of pharyngeal length from anterior end. Ventral gland pore situated at 115-125 μm of pharyngeal length from anterior end. Cardia round, small (12-14 μm), surrounded with intestinal tissue. Reproductive system diorchic, testes outstretched. Spicules paired, equal and arcuate with a central lamella, 51-55 μm long as arc (1.4-1.5 a.b.d). Gubernaculum with long straight dorsocaudally directed apophyses, 22-25 μm long. 9-12 minute mid-ventral supplementary papillae observed in precloacal region. Short precloacal setae (3 μm long) just anterior to cloaca. Tail consisted proximal conical and distal cylindrical part (45-58 μm). Tail 3.9-4.2 a.b.d long with three short terminal setae (about 3-5 μm long), three caudal glands, and prominent spinnerret. Other tail setae (about 4-5 μm) arranged in approximately four dorso- and ventrolateral longitudinal rows.

Females ( Fig. 4 , Table 4). Similar to male. Vulva at 43.1-46.2% of body of length. Didelphic, outstretched ovaries.

Remarks. Vasostoma brevispicula Huang & Wu, 2011 is characterized by its thin and long body, a tubular buccal cavity with three small teeth, a long pyriform oesophageal bulb and curved spicules with a central lamella ( Huang and Wu, 2011). The specimens from the East Sea, Korea, generally conform to the original description of Vasostoma brevispicula by Huang & Wu (2011), with slight differences in body width (41-48 μm vs. 37-56 μm) and body length (2009-2425 μm vs. 2119-2906 μm). We interpret this variation as intraspecific diversity.

Figures

Fig. 4. Vasostoma brevispicula Huang & Wu, 2011, from the East Sea, Korea. A, Male head, showing amphideal fovea and cuticular ornamentation at the head region; B, Male head; C, Male Pharynx; D, Female vulva; E, Male precloacal and anal region. Scale bars: 20μm (A, B) and 100 μm (C-E).