Enoploides parakoreanus, Meng & Liang & Wang, 2025

Meng, Zhiyu, Liang, Huixin & Wang, Chunming, 2025, Phylogenetic analysis within Monhysteridae and Thoracostomopsidae based on rDNA sequences and two new species from the Yellow Sea, China, Zoosystematics and Evolution 101 (3), pp. 1339-1358 : 1339-1358

Enoploides parakoreanus sp. nov.

Figs 3 , 4 , 5 , Table 4

Type material.

One male and three females were measured and studied. Holotype: m # 1 on slide 23 TJGK-D-3-2-1 ; paratypes: f # 1 on 23 TJGK-X-4 , f # 2 on 23 TJGK-D-3-1-2 ; f # 3 on 23 TJGK-D-3-1-10 .

Type locality and habitat.

All specimens were collected from Changdao Island, Shandong Province, China. 38°9'N, 120°44'E ( TJGK), 0–8 cm sediment depth, sandy sediment.

Etymology.

The specific name refers to the morphological character similar to Enoploides koreanus .

Measurement.

All measurement data can be found in Table 4 .

Description.

Male. Body medium-sized and cuticle smooth. Three lips high, with its border heavily striated with grooves, each lip with two inner labial setae (0.62 head diameters in length). Six longer outer labial setae and four shorter cephalic setae in one circle, situated at anterior portion of cephalic capsule. Eight subcephalic setae at posterior end of cephalic capsule, two in each group. Buccal cavity wide and funnel-shaped, armed with three equally sized mandibles. Mandibles Y-shaped, two lateral bars each with claw-like distal end converging into one solid bar, curving inwards to the lumen. Three onchia equal-sized, posterior to each base of mandible. Amphidial fovea not observed. Pharynx long with grooves and sinuous external contours. Nerve rings anterior to middle pharynx region (30.6 % of pharynx length). Secretory-excretory pore not observed. Cardia inverse triangular shaped, embedded into the intestine. Somatic setae irregularly scattered along the cervical region. Metanemes not observed.

Testes paired and outstretched, anterior and posterior testes to the right of the intestine. Spicules paired, slightly curved, 0.82 cloacal body diameters in length. Gubernaculum simple, sleeve-shaped, parallel to distal end of spicules. Precloacal supplement tubular-shaped, 8 µm in length, 105 µm from cloacal. Tail conical-cylindrical. Caudal setae present and two caudal glands with a common duct.

Female. Similar to males in most respects except subcephalic setae absent. Vulva located at posterior portion of the body (62–64 % of the body length from the anterior end). Reproductive system didelphic-amphidelphic, ovaries reflexed. Vagina with thick walls and well-developed sphincter muscles.

Diagnosis.

Enoploides parakoreanus sp. nov. is characterized by body medium-sized, mandibles Y-shaped with distal end claw-like, three equal-sized teeth, spicules paired and slightly curved, gubernaculum sleeve-shaped and enclosing the distal end of spicules, precloacal supplement tubular-shaped, tail conical-cylindrical.

Genus Enoploides consists of 27 valid species and can be divided into two groups by the length of spicules: the first group with short spicules (<150 µm); the second group with long spicules (> 150 µm). Enoploides parakoreanus sp. nov. belongs to the first group. The new species differs from other species of Enoploides with spicules slightly curved. Enoploides parakoreanus sp. nov. is similar to E. cirrhatus Filipjev, 1918 , E. disparilis Sergeeva, 1974 , E. koreanus Jeong, Tchesunov & Lee, 2020 , with short spicules, but differs from E. cirrhatus in body length (2627–3382 µm vs. 4350 µm), de Man’s a values (46.9–56.6 vs. 26), and precloacal supplement (one tubular supplement vs. seven pairs of precloacal papillae) ( Filipjev 1918); differs from E. disparilis in precloacal supplement (one supplement vs. absent), de Man’s c ratio (16.6–18.7 vs. 9) ( Sergeeva 1974); differs from E. koreanus in outer labial setae length (51–67 µm vs. 30–43 µm), spicules shape (spicules slightly curved vs. curved at obtuse angle), and gubernaculum length (21 µm vs. 12 µm) ( Jeong et al. 2020).

Figures

Figure 3. Enoploides parakoreanus sp. nov. A. Lateral view of the male anterior region, showing the pharynx region; B. Lateral view of the male anterior region, showing buccal cavity; C. Lateral view of the male anterior region; D. Lateral view of the female anterior region; E. Lateral view of the female posterior region; F. Spicules and gubernaculum; G. Lateral view of the male posterior body. Scale bars: 80 µm (A); 30 µm (B, C, G); 50 µm (D, E); 20 µm (F).

Figure 4. Enoploides parakoreanus sp. nov. A. Lateral view of the male entire body; B. Lateral view of the female entire body. Scale bars: 150 µm.

Figure 5. Enoploides parakoreanus sp. nov. A. Lateral view of the male anterior region, showing cephalic setae and mandibles; B. Lateral view of the male anterior region, showing tooth; C. Lateral view of the male posterior body, showing spicules and gubernaculum; D. Lateral view of the male posterior body, showing precloacal supplement. Scale bars: 20 µm (A – D).