Trichromadora spheribulba, Lv & Yu & Wang, 2025

Lv, Yanwei, Yu, Huiying & Wang, Mengna, 2025, Two new nematode species: Axonolaimus rushanensis sp. nov. (Axonolaimidae) and Trichromadora spheribulba sp. nov. (Chromadoridae) from the Yellow Sea, China, Zootaxa 5653 (3), pp. 379-395 : 388-391

Trichromadora spheribulba sp. nov.

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( Figures 4–5 , Table 3)

Type material. Three males and three females were studied. Holotype: ♂ 1 on 2021RSGHGY 4–2–22; paratypes: ♂ 2 on 2021RSGHGY4–2–21; and ♂ 3 on 2021RSGHGY 4–2–3; ♀ 1 on 2021RSGHGY 4–2–23; ♀ 2 on 2021RSGHGY 4–2–19; and ♀ 3 on 2021RSGHGY 4–2–18.

Type locality and habitat. Specimens were collected from intertidal sandy sediment at Rushan, Shandong Province, China. 36º95´N, 121º96΄E ( Figure 1) .

Etymology. Species epithet spheribulba refers to the pharynx bulb shape.

Measurements. All measurement data are given in Table 3.

Descriptions.

Males. Body long and slender, blunt at the anterior end and tapering towards the tail end. Heterogeneous cuticle ornamented with transverse rows of evenly spaced, rounded punctations extending from the anterior body region to pharyngeal bulb region. Posterior to pharyngeal bulb, several punctations in the medial row conspicuously larger than adjacent punctations within the same transverse row until the mid-body region. Due to the close proximity of these enlarged punctations, their exact number is uncertain. Posterior to the mid-body, three punctations per transverse row markedly thickening, forming three distinct longitudinal lateral rows. Among these, the largest medial punctation transitions into rectangular markings until the cloacal region. Posterior to the cloaca, the ornamentation small, uniformly rounded punctations extending to the tail terminus. Six inner and six outer labial sensilla papilliform, four long cephalic setae 12–13 µm (0.7–0.8 cephalic diameter in length). Several somatic setae scattered at the anterior end of pharyngeal bulb region. Amphidial fovea situated anterior to cephalic setae, faint slit-like, 0.4 as wide as the corresponding body diameter. Buccal cavity shallow, 8–9 µm in depth, with one large dorsal hollow tooth and two small subventral teeth. Pharynx muscular and cylindrical, posterior region swollen into a distinct bulb (19–22 % of pharynx length). Nerve ring surrounds the pharynx at 55–57 % of the pharyngeal length from the anterior. Secretory-excretory system present. Cardia not observed. Tail conical and gradually tapering to the spinneret, 5.8– 8.5 cloacal body diameter in length.

Reproductive system with a single, outstretched testis located to the right of the intestine. Spicules evenly curved and arc-shaped (1.3–1.5 cloacal body diameter in length). Gubernaculum boat-shaped, surrounding the distal end of spicules, swollen in the middle part. Seven precloacal supplements cup-shaped (arranged in two groups: 3+4), three supplements close to cloaca equally-distanced (10–14 µm), the other four equally-distanced (10–14 µm), but the distance between the two groups is larger (15–18 µm).

Females. Similar to males in most characteristics. Contrast to males’ cuticle, without rectangular markings present. Reproductive system didelphic, with opposed and reflexed ovaries. Anterior ovary to left of intestine and posterior ovary to right of intestine. Spermatheca present. Vulva situated posterior to middle of body (53.9–55.8% body length). Vagina short and muscularized with thick walls.

Differentiational diagnosis and discussion. Trichromadora spheribulba sp. nov. is characterized by body long and slender, buccal cavity with three hollow teeth, pharynx with an obvious posterior bulb, spicules long and arc-shaped, gubernaculum boat-shaped and swollen in the middle part, seven cup-shaped supplements in two groups and unequidistant.

The new species was assigned to the genus Trichromadora based on the presence of three distinct longitudinal lateral rows extending from the mid-body to the cloacal region, along with hollow teeth.According to the diagnostic ( Figure 6 ) and morphometric characters ( Table 4) of three valid species of the genus, T. spheribulba sp. nov. is similar to T. arimiensis in cuticle ornamentation, cephalic setae length, spicules shape and tail shape, but can be differentiated from the latter in body length (1081–1334 µm vs. 770–890 µm), amphidial fovea shape (slit-like vs. spiral), pharynx shape (posterior bulb obvious vs. posterior bulb weak), spicules length (35–39 µm vs. 27 µm), gubernaculum apophysis length (24–26 µm vs. 20 µm), precloacal supplements number (7 vs. 5) and tail length (138–173 µm vs. 56–120 µm). Meanwhile, the new species significantly differs from T. brachyura in body length (1081–1334 µm vs. 600 µm), cephalic setae length (12–14 µm vs. 2.64 µm), spicules length (35–39 µm vs. 17.6 µm), precloacal supplements number (7 vs. 4) and tail length (138–173 µm vs. 52 µm); differs from T. longicaudata in longer body (1081–1334 µm vs. 897–1081 µm), longer cephalic setae (12–14 µm vs. 4–5 µm), longer spicules (35–39 µm vs. 17–22 µm), longer gubernaculum apophysis (24–26 µm vs. 10–11 µm), more precloacal supplements (7 vs. 5) and shorter tail (138–173 µm vs. 164–293 µm). Furthermore, differences between T. spheribulba sp. nov. and other congeners are listed in the key below.

Figures

FIGURE 4. Trichromadora spheribulba sp. nov. A. Lateral view of male anterior region showing buccal cavity, cephalic setae and pharyngeal region; B. Lateral view of male anterior region showing teeth; C. Lateral view of male anterior region showing amphidial fovea and cuticle; D. Lateral view of female anterior region showing buccal cavity, cephalic setae and pharyngeal region; E. Lateral view of female whole body; F. lateral view of female posterior body; G. Lateral view of male posterior body showing spicules, gubernaculum and precloacal supplements; H. Showing spicules and gubernaculum. Scale bars: A, B, C, D, F, G = 20 µm, E = 50 µm.

FIGURE 5. Trichromadora spheribulba sp. nov. A. Lateral view of male anterior region showing cuticle and cephalic setae; B. Lateral view of male anterior region showing buccal cavity and teeth; C. Lateral view of male posterior body showing spicules; D. Lateral view of male posterior body showing gubernaculum and precloacal supplements. E. Lateral view of male anterior region showing amphidial fovea; F. Lateral view of male anterior region showing pharyngeal bulb. Scale bars: A, B, C, D, E, F = 20 µm.

FIGURE 6. Pictorial key for identification of species of the genus Trichromadora Kreis, 1929.