Aponema ninae Portnova, 2009
The body is short and slender. The cuticle is thin and finely striated. The striation is easily visible all over the body. There are four rows of pores associated with the hypodermal glands situated sublateral along the whole body.
The amphidial fovea is distinctly sclerotized and circular, and has an interruption in the posterior part, 4–5 µm in diameter (about 44.4–55.5 % of the corresponding body diameter). The distance from the cephalic end to the anterior border of the amphidial fovea is 10–12 µm. The head is small, and is offset by a slight constriction. There are four cephalic setae, each 2.5–3 µm long. The inner and outer labial sensilla are not visible using a light microscope. The somatic setae are 2–4 µm long, and are scattered along the body.
The stoma is small, narrow and weakly sclerotized. There is a dorsal thickening of the cuticle observed in the buccal cavity, which resembles the subventral tooth described by other authors. Obvious dorsal and subventral teeth are not present. The oesophagus is cylindrical and muscular along its entire length. It is enlarged posteriorly into a spherical bulb, measuring 18 µm wide and 20 µm long. The intestine gleam was examined. The cardia is small and oval. The glandular body of the renetta cell is sacciform, and extended, with granular content.
A single anterior testis is situated to the left side of the intestine. The spicules are short, curved, slightly widened and cephalated proximally, measuring 18.3 µm (arch), and 12.2 µm (chord). The gubernaculum is strongly sclerotized with a wide and bevelled top to the apophyses, 6.1 µm long. The sperm cells have an irregular form, and the testis is densely filled. Precloacal supplements are absent.
The female reproductive system is didelphic, with posterior and anterior outstretched ovaries of equal length. The ovaries are located to the right of the intestine.
The tail is long, slender, and narrowed, with a drop–shaped tip, measuring 3.2–3.6 times the anal body diameter in males and 3.8–4.4 times in females.
There is one caudal seta on the terminal part of the tail, measuring 3–4 µm long.
Ecology and Distribution
Haakon Mosby Mud Volcano, Norwegian Sea, at 1,288m (Portonova, 2009).