Hopperia beaglense Chen & Vincx, 1998

Fu, Sujing, Mou, Jianfeng, Liu, Kun, Zhang, Shuyi & Lin, Heshan, 2025, Two new species and a new record of Comesomatidae (Nematoda, Araeolaimida) from the Southern Ocean, ZooKeys 1244, pp. 121-145 : 121-145

Hopperia beaglense Chen & Vincx, 1998

Figs 10 , 11 , 12 , Table 4

Material examined.

• Three males, collected in the Prydz Bay , 68.2833°S, 75.5827°E; depth 578 m; collected on 31 Dec. 2020; Jianfeng Mou leg.; total organic carbon 1.37 %; sand, 7.87 %; clay, 16.77 %; silt 75.37 %; mean particle diameter 6.20 μm; on slide no. MBSMCOIA -M 10 D-3-5-10 , MBSMCOIA -M 10 D-1-2-5-4 and MBSMCOIA -M 10 D-1-5-10-1 ; female specimen was collected from Antarctic Peninsula , 61.0046°S, 54.6971°W; depth of 574 m; collected on 28 Dec. 2022; Jianfeng Mou leg.; muddy sediment; on slide no. MBSMCOIA -DA-04-2-5-1 .

Measurements.

All measurement data are given in Table 4 .

Description.

Male. Body long (1618–1760 μm long), narrowing gradually towards both extremities. Cuticle with transverse rows of punctations starting from amphid to near tail tip. Lateral differentiation with larger, irregularly spaced punctations. Short somatic setae sparsely present on entire body, ~ 3 μm long. Cephalic region with distinct constriction at level of cephalic setae. Anterior sensilla in three crowns: six small inner labial papillae, six outer labial setae (2 μm long), and four cephalic setae (4–5 μm long or 0.30–0.33 corresponding body diameter long). Anterior buccal cavity cup-shaped, and the posterior portion cylindrical. Three cuticularized pointed teeth present at the junction between the two compartments of buccal cavity. Spiral amphidial fovea with 3.5 turns, 11–12 μm in diameter or 62–69 % of corresponding body diameter, anterior border located at the level of cephalic setae. Pharynx cylindrical, gradually broadening posteriorly and forming a weak posterior bulb. Nerve ring situated at 42–47 % of anterior pharynx. Secretory-excretory gland located posterior to pharynx. Secretory-excretory pore located slightly posterior to nerve ring, 96–109 μm from the anterior end. Cardia small, partially surrounded by intestinal tissue. Reproductive system diorchic, anterior outstretched testis to the left or right of intestine and posterior outstretched testis to the right of the intestine. Spicules arcuate, equal, 1.3–1.4 cloacal body diameters long, proximal part of spicule with central cuticularized projection (lamella) extending from proximal end to ~ 1 / 4 of spicule. Gubernaculum with slightly curved dorso-caudal apophyses, 25–27 μm long. One precloacal seta 3 μm long. Seven tubular precloacal supplements. Conical tail 1.8–2.2 cloacal body diameters long, two terminal setae (4 μm long). Three caudal glands present.

Female. Similar to males, but shorter than males. Reproductive system with two opposed, outstretched ovaries, with anterior ovary to the left of intestine and posterior ovary to the right of intestine. Vulva at 51 % of body length from anterior. Granular vaginal glands present. Three caudal glands present.

Remarks.

Hopperia beaglense was first described by Chen and Vincx (1998) from the Strait of Magellan and the Beagle Channel, based on specimens collected at 100–110 m water depth with muddy sediment. The present specimens were collected from muddy sediment and at greater water depths (574–578 m). This species differs from all other Hopperia species by the conical tail tip. The present specimens are similar to the description by Chen and Vincx (1998), and there are some differences in the value of a (20–25 in present specimens vs 30–41 in the Chilean specimens), maximum body diameter in males (71–85 μm in present specimens vs 41–49 μm in the Chilean specimens), and the present specimens lack the supplement-like structure situated halfway down the ventral side of the tail. This species was also recorded in Kaikoura Canyon, New Zealand ( Leduc 2012). So, H. beaglense has a circumpolar distribution.

Figures

Figure 10. Hopperia beaglense Chen & Vincx, 1998. A. Entire male; B. Entire female.

Figure 11. Hopperia beaglense Chen & Vincx, 1998. A. Male anterior body region; B. Surface view of male anterior body region showing amphidial fovea and cephalic sensilla; C. Male pharyngeal body region; D. Male posterior body region; E. Female posterior body region.

Figure 12. Hopperia beaglense Chen & Vincx, 1998. Light micrographs. A. Male anterior part showing buccal cavity; B. Surface view of male anterior body region showing amphids; C. Lateral punctations of female anterior body region; D. Male posterior part showing precloacal supplements; E. Male spicular apparatus; F. Female tail.