Litinium macramphida, Wen & Huixin & Mengna & Chunming, 2023

Wen, Guo, Huixin, Liang, Mengna, Wang & Chunming, Wang, 2023, Description of two new species of Nematoda: Litinium macramphida sp. nov. (Oxystominidae) and Cyartonema breviseta sp. nov. (Cyartonematidae) from the Yellow Sea, China, Zootaxa 5339 (6), pp. 577-586 : 579

Litinium macramphida sp. nov.

( Figures 1–2 , Table 1 )

Type material. Two males were measured and studied. Holotype: ♂ 1 on slide 22HSB3-3-17 , paratype: ♂2 on slide 22HSB 3-3-26.

Type locality and habitat. Specimens were collected from intertidal muddy sediment at Rizhao coast, Shandong Province; 35º18´N, 119º31΄E; 0–2 cm sediment depth.

Etymology. Species epithet macramphida is derived from macro, which refers to the large amphideal fovea.

Description. Males. Body long, tapering slightly towards anterior and posterior end. Cuticle smooth, without striations. Six inner and six outer labial sensilla setiform, arranged in two separate circles. Four cephalic setae situated at level of amphids posterior end, 1.6–1.7 head diameter from anterior end. Amphideal fovea drop-shaped, 3 μm from anterior region, and wide (81–88% of c.b.d.—corresponding body diameter) with lightly cuticularized outline.Amphideal aperture ovoid, 18 μm in length and 7 μm in width. Buccal cavity narrow and cylindrical without cuticularized armature. Pharynx muscular and cylindrical, posterior end widened but not forming bulb. Nerve ring positioned slightly anterior to half pharynx length (37.8%–38.2% pharynx length). Secretory-excretory system and cardia not observed.

Reproductive system with two opposed and outstretched testes, anterior testis to the right of intestine and posterior to the left of intestine. Spicules short, 1.4 cloacal body diameter along arc, slightly curved and broad with internal stripes. Gubernaculum simple and parallel to the distal end of spicules. Two precloacal supplements consists of cuticularized swellings, each with one single precloacal setae (4 μm in length). Posterior precloacal supplement located 23 μm from cloacal pore and anterior supplement 42 μm from the first supplement. Tail conical, gradually tapering with a rounded tip, two caudal glands present, and caudal setae absent.

Females not found.

Differentiation diagnosis and discussion. Litinium macramphida sp. nov. is characterized by relatively long body, inner and outer labial sensilla setiform and with same length, amphideal fovea 81–88% of c.b.d, spicules short and broad, gubernaculum simple, two precloacal supplements present, tail conical with rounded tip.

Litinium macramphida sp. nov. differs from other species of Litinium in the large amphideal fovea, and similar to L. aequale , L. curticauda , L. egregius , L. gludi , L. longicaudatum , L. profundorum and L. subterraneum in the presence of two precloacal supplements. The new species differs from L. aequale in body length (2216–2456 μm vs. 1663–1900 μm) and tail length (4.19–4.75 cloacal body diameter vs. 0.88 cloacal body diameter); from L. curticauda in inner and outer labial sensilla length (5–6, 5–6 μm vs. 1.5, 1.4 μm), cephalic sensilla length (9–11 μm vs. 2.1 μm), and spicules length (21–22 μm vs. 46.5–49 μm); from L. egregious in body length (2216–2456 μm vs. 2998–3072 μm), inner and outer labial sensilla length (5–6, 5–6 μm vs. 2.5–3.3, 2.5–3.3 μm), cephalic sensilla length (9–11 μm vs. 4–5 μm), spicules length (21–22 μm vs. 37 μm); from L. gludi in body length (2216–2456 μm vs. 895–1066 μm), cephalic sensilla length (9–11 μm vs. 1.5–2.0 μm), and tail length and shape (4.2–5.1 cloacal body diameter, conical vs. 6.9–9.3 cloacal body diameter, conico-cylindrical); from L. longicaudatum in inner and outer labial sensilla length (5–6 μm vs. 1.3 μm), cephalic sensilla length (9–11 μm vs. 3.6 μm), anterior body shape (equal in width vs. abruptly sharpened), and tail length and shape (conical, 67–76 μm vs. conical-cylindrical, 133– 137 μm); from L. profundorum in body length (2216–2456 μm vs. 1196 μm), inner labial sensilla length (5–6 μm vs. 2 μm), cephalic sensilla length (9–11 μm vs. 5.5 μm), and tail length (4.2–5.1 cloacal body diameter vs. 1.2 cloacal body diameter); from L. subterraneum in the inner and outer labial sensilla length (5–6, 5–6 μm vs. 2.5–4, 2.5–4 μm), cephalic sensilla length (9–11 μm vs. 2–4 μm), and amphideal diameter and amphideal fovea shape (81–88% c.b.d., ovoid shaped vs. 50–62% c.b.d., transversely oval anterior shaped).

Figures

FIGURE 1. Litinium macramphida sp. nov. A. Lateral view of male anterior end, showing pharynx region; B. Lateral view of male anterior portion, showing buccal cavity; C. Lateral view of male anterior portion, showing amphideal fovea and cephalic setae; D. Spicules and gubernaculum; E. Lateral view of male posterior portion; showing precloacal supplements. F. Lateral view of male entire body. Scales: A, F=50 μm; B, C, D, E, = 20 μm.

FIGURE 2. Litinium macramphida sp. nov. A. Lateral view of male anterior portion, showing amphideal fovea and cephalic setae; B. Lateral view of male anterior end, showing buccal cavity; C. Lateral view of male posterior portion, showing tail end; D. Lateral view of male posterior portion, showing spicules; E. Lateral view of male posterior portion, showing gubernaculum and precloacal supplements. Scales: A, B, C, D, E = 20 μm.