Hofmaenneria coralis, Phuong & Long & Thanh & Tu, 2023

Phuong, Nguyen Thi Xuan, Long, Phan Ke, Thanh, Tran Thi Viet & Tu, Nguyen Dinh, 2023, Corononema vulgare sp. n. and Hofmaenneria coralis sp. n. (Nematoda, Monhysterida) from coral reefs off the coast of Vietnam, Zootaxa 5380 (1), pp. 67-76 : 72

Hofmaenneria coralis sp. n.

( Figures 3 and 4 ; Table 2 )

Type material. Holotype male, inventory slide number MSS-SH 1, 2; deposited in the Vietnam National Museum of Nature, Vietnam Academy of Science and Technology (Hanoi, Vietnam) . Paratypes: 10 ♂, slide number CD-2020-7 (6 specimens) and CD-2020-8 (4 specimens), and 7 ♀, slide number CD-2020-9; deposited in the collection of nematodes of the Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology (Hanoi, Vietnam) .

Type locality. Shallow area off the coast of Vietnam. Coral reef from Con Son Island , Con Dao Archipelago , Ba Ria-Vung Tau Province. Coordinates : 8038 ʹ53ʹʹN, 106034 ʹ51ʹʹE. Depth : 1.8 m. Water salinity: 35 ‰.

Etymology. The specific epithet means “coral”.

Descriptions.

Males. Body thin, medium size. Cuticle strongly annulated. Both anterior and posterior body ends narrowed. Cuticle setae numerous, 5–7 µm long. Labial region not separated from the rest of the body. Six internal labial sensillae in the shape of papillae; six outer labial sensillae and four cephalic sensillae in the shape of thin setae, arranged in two circles. Outer labial setae 12–15 µm long, approximately equal to the width of labial region. Cephalic setae 8–10 µm long. Cheilostoma well-developed, spacious, and set off from pharyngostoma by a cuticular ring. Gymnostoma in the shape of short and wide cylinder with cuticularised walls, 3µm long and 6µm wide. Two small denticles at the gymnostoma. Stegostoma funnel-shaped, with thick walls. Amphidial fovea in the shape of ring 5.0–6 µm diameter and located 18–22 µm from anterior body end. Pharynx muscular, equally thickened along its entire length. Cardia small, protruding into the lumen of the intestine.

Testis single, straight, located to the right of the intestine. Spicules comparatively short, strongly curved; with heads, 30–34 µm long. Gubernaculum thin, straight, 10–12 µm long. Tail long, gradually narrowing. Caudal setae 5–7 µm long; terminal setae 9 µm long; subterminal setae 17–19 µm long. Caudal glands and spinneret present.

Females. General morphology similar to that of males. Structure of cuticle and anterior body end as in males. Cuticle annulated. Labial region not separated from the rest of the body. Six internal labial sensillae in the shape of papillae. Six outer labial sensillae and four cephalic sensillae in the shape of thin setae. Outer labial setae 13–15 µm long; cephalic setae 8–10 µm long. Cheilostoma obvious, set off from pharyngostoma by a cuticular ring. Gymnostoma in the shape of a short and thin cylinder with strong cuticular walls. Amphidial fovea circular, with 4.0 µm diameter and located 19–24 µm from anterior body end. Pharynx cylindrical, muscular. Cardia small. Cardial glands not observed.

Reproductive system monodelphic, prodelphic. Ovary comparatively long and located subventrally on the right side of the intestine. Vulva postequatorial, in the form of transverse slit. Vulva lips not sclerotized. Vagina short, with thin walls and sloping towards the posterior body end. Uterus spacious, filled with numerous sperms. Posterior uterus sack and postvulval gland cell not observed. Tail long, gradually narrowing. Caudal setae 5–7 µm long; terminal setae 8–9 µm long. Caudal glands and spinneret present.

Differential diagnosis. At present the genus Hofmaenneria Gerlach & Meyl, 1957 includes 11 valid species ( Gagarin & Naumova 2022). The new species morphology is close to H. niddensis Gerlach & Meyl, 1957 and H. optata Alekseev, 1983 . It differs from the first species by the thinner body (a = 44–56 vs a = 35–44 in H. niddensis ), shorter and less slender tail (c = 7.0–12.6, cʹ = 5.0–8.2 vs c = 4.8–6.1, cʹ = 8.3–9.7 in H. niddensis ), and shorter spicules (30–34 µm long vs 36 µm long in H. niddensis ) ( Gerlach & Meyl 1957). H. coralis sp. n. differs from the second species by the longer body (♂♂ L = 1046–1293 µm, ♀♀ L = 1172–1202 µm vs ♂♂ L = 920 µm, ♀♀ L = 890–910 µm in H. optata ), comparatively thinner body in females (♀♀ a = 46–56 vs ♀♀ a = 28–37 in H. optata ), comparatively shorter pharynx (♂♂ b = 5.4–6.7, ♀♀ b = 5.7–6.3 vs ♂♂ b = 4.6, ♀♀ b = 3.8–3.9 in H. optata ), comparatively shorter tail (♂♂ c = 9.8–12.6, ♀♀ c = 7.0–10.8 vs ♂ c = 6.7, ♀♀ c = 6.0– 6.4 in H. optata ) and longer outer labial setae (♂♂ 12–15 µm vs ♂♂ 8–10 µm in H. optata ) ( Alekseev 1983).

Figures

FIGURE 3. Hofmaenneria coralis sp. n. Holotype male and paratype female. A: male, head; B: male, anterior body end; C: female, vulva region; D: female, posterior body end; E: spicules and gubernaculum; F: male, posterior body end. Scale bars: A—10 µm; B—50 µm; C, F—30 µm; D—40 µm; E—15 µm.

FIGURE 4. Hofmaenneria coralis sp. n. Holotype male and paratype female. A: male, entire body; B: female, entire body; C: male, anterior body end; D and E: male head; F and G—female head; H: female, vulva region; I: male, cloaca region; J: male, posterior body end; K: female, posterior body end L: male, tail end. Scale bars: A—100 µm; B—200 µm; C—50 µm; D, E, F, I, L—5 µm; G—10 µm; H, J, K—20 µm.