Manganonema kitasatoi, Leduc, Daniel, 2015

Leduc, Daniel, 2015, One new genus and five new nematode species (Monhysterida, Xyalidae) from Tonga and Kermadec Trenches, Southwest Pacific, Zootaxa 3964 (5), pp. 501-525 : 514

Manganonema kitasatoi n. sp.

( Figs 8–9 )

Measurements. See Table 2.

Type specimens. Holotype male (99746), collected 12 October 2013 (JAMSTEC cruise YK13-10, deployment 2-3, core 1). Two paratype males and two paratype females (99747), collected 12 October 2013 (JAMSTEC cruise YK13-10, deployment 2-3, core 1).

Type habitat. Horizon Deep, Tonga Trench (174.75224º W, 23.27514º S), water depth: 10811 m, sediment depth: 0–3 cm.

Etymology. This species is named after Dr Hiroshi Kitazato, leader of JAMSTEC cruise YK13-10 to Tonga Trench.

Description. Males. Body long, cylindrical, tapering slightly towards anterior and posterior extremities. Striated cuticle, ~1–1.5 µm thick. Anterior extremity dummy-shaped, with narrow, rounded, and slightly swollen head set off from rest of body by slight constriction. Somatic setae not observed; one pair of short, 1–2 µm long sub-cephalic setae, one situated latero-ventrally and the other latero-dorsally, immediately posterior to the amphideal fovea. Six minute inner labial papillae; six outer labial setae and four cephalic setae of similar length in one circle, 2–4 µm long. Large circular amphideal fovea with cuticularised outline and opening of sensillar canal visible as central fleck ( Fig. 8 A, C). Buccal cavity minute. Pharynx muscular with oval posterior bulb; cardia small. Nerve ring situated at 55–60% of pharynx length from anterior. Secretory-excretory system not observed. Tail conico-cylindrical, with gradually tapering distal end; at least two caudal glands present, difficult to observe. Caudal and terminal setae not observed.

Male reproductive system diorchic with two opposed and outstretched testes; anterior testis to the left of intestine and smaller posterior testis to the right of intestine. Sperm cells small, spherical to globular, ~3 × 3 µm. Spicules short, 0.45–0.54 abd long, wide proximally and tapering distally, conical in shape. Gubernaculum and precloacal supplements/setae not observed.

Females. Similar to males but with slightly smaller amphideal fovea. Reproductive system monodelphic with single anterior outstretched ovary situated to the left of intestine; germinal zone comprising about half of gonad length. Vulva situated at almost two thirds of body length from anterior; pars proximalis vaginae surrounded by thin constrictor muscle. A single vaginal gland present posterior to vagina.

Diagnosis. Manganonema kitasatoi n. sp. is characterised by long body (1114–1279 µm), absence of somatic setae, presence of one pair of sub-cephalic setae immediately posterior to the amphideal fovea, presence of two opposed testes and short, conical spicules in males, and conico-cylindrical tail 5.1–6.8 abd long.

Differential diagnosis. Manganonema kitasatoi n. sp. can be differentiated from most other species of the genus except M. rowdeni n. sp. and M. majusculum n. sp. by the long body (>1100 µm), presence of a pair of subcephalic setae posterior to each amphideal fovea, and presence of two testes. Manganonema kitasatoi n. sp. can be

Figures

FIGURE 8 Manganonema kitasatoi n. sp. Male holotype. A: Lateral view of head; B: posterior body region; C: anterior body region; D: gonads; E: entire male. Arrow shows location of spicule. Scale bar: A = 20 µm; B = 25 µm; C = 32 µm; D = 60 µm; E = 135 µm.

FIGURE 9 Manganonema kitasatoi n. sp. Female paratypes. A: Lateral view of head; B: posterior body region; C: anterior body region; D: gonads; E: entire female. Scale bar: A = 20 µm; B = 38 µm; C = 32 µm; D = 60 µm; E = 170 µm.