Bathynema nodinauti, Miljutin & Miljutina, 2009

Miljutin, Dmitry M. & Miljutina, Maria A., 2009, Description of Bathynema nodinauti gen. n., sp. n. and four new Trophomera species (Nematoda: Benthimermithidae) from the Clarion-Clipperton Fracture Zone (Eastern Tropic Pacific), supplemented with the keys to genera and species *, Zootaxa 2096 (1), pp. 173-196 : 175-176

Bathynema nodinauti gen. n. sp. n.

Figs 1–2 ; Table 1

Type material: Holotype: one mature male, collection number MNHN-BN493 .

Type locality: Polymetallic nodule area, 14°02.7’N, 130°07.73’W, 4950 m depth, 03.06.2004, multicorer #16, corer #4.

Etymology: In honor of NODINAUT research cruise.

Description: Male. Body cylindrical, with thickest body part at anterior half of body; anterior end rounded, posterior end cone-shaped with thick and short cylindrical terminal part approximately 1/4 of tail, length rounded at its tip. Cuticle 2 µm thick and showing transverse striation along whole body length. Four short submedian cephalic setae 4 µm long inserted in tiny pits. Flat cervical lateral alae present at level of anterior part of pharynx, beginning at approximately 2/5 distance from anterior end to amphid and about 0.5 c.b.d. wide at level of amphid. Each lateral ala anteriorly single-lobed (approximately 2/5 ala length) and posteriorly bilobed (approximately 3/5 ala length). Amphid located at beginning of bilobed part of alae and between the lobes i.e. at approximately 1.6 c.b.d. from anterior end. Amphidial aperture round, 3.5 µm in diameter; canalis amphidialis with thick cuticular walls at distal part but gradually becoming thinner towards proximal end of the amphidial canal. Single lateral cervical short setae 3.0–3.5 µm long present between both posterior lobes of each ala at nearly double distance from anterior end to amphidial aperture. Mouth opening reduced to indistinct intracuticular apical tube. Pharynx slightly enlarged towards its posterior end and bipartite i.e. consisting of a short atrophied anterior part (10–15% of total length of pharynx) devoid of muscle cells and inner lumen and visible as a cellular mass, and a long posterior muscular part provided with an axial inner lumen and surrounded by longitudinal muscles; this inner lumen also irregular with wide and narrow parts, as well as meandering. Several large hyaline cells situated around posterior part of pharynx. Nerve ring located at level of middle of pharynx. Two large hyaline cells approximately 0.5 c.b.d. in diameter located at anterior part of midgut; each cell with a large single nucleus and a single nucleolus. Cardia absent. Midgut an oligocellular trophosome without visible internal lumen and obviously consisting of 1 row of large cells, except most anterior part consisting of several small trophosomal cells. All trophosomal cells containing large hyaline granules; borders between cells distinct. Male reproductive system diorchic, occupying approximately 2/3 of total body length and consisting of two outstretched testes (each about 450 µm long) arranged consecutively in tandem and connected by joint spermaduct (130 µm long), vas deferens (650 µm long), and two spicules. Spicules moderately bent, consisting of long, relatively optically dense lamina and a short, funnel-shaped, relatively hyaline, proximal part (capitulum). Capitulum ventrally bent and evidently representing a flexible structure (this supposition is based on the location of capitulum at different angles in different spicules). Four midventral short supplementary setae present anterior to cloacal opening. Caudal glands absent.

Host unknown.

Female, juvenile stages: unknown.

Degree of maturity gravid

L, µm 2670

a 65.0

c 26.0

c' 3.2

Ratio of ‘length of genital system / total body length’, % 70

Amph.dist. 51

Cephalic sensilla length, mkm 4.0

Spicule length (µm):

in chord 43

in arc 51

Amphidial aperture diameter, µm 3.5

Maximal body diameter, µm 45

Body diameter (µm) at level of:

cephalic sensilla 16

amphid 36

1/4 body length 45

midbody 44

3/4 body length 42

anus 32

Remarks: Two large hyaline cells at level of anterior part of midgut may be considered as cellular bodies of secretory-excretory system (renetta). However, neither channel nor outlet of renetta has been found. However, these hyaline cells may be also interpreted as a vestigial dorsal gland. In earlier larvae of benthimermithids, this gland together with a stylet in the anterior part of pharynx forms a complex whereby larvae penetrate into host’s internal issues ( Chesunov 1997). This complex usually disappears at later larval stages, however, some mass of hyaline cells located between the pharynx and trophosome was also noted in male of T. australis ( Petter 1983b) .

Figures

FIGURE 1. Bathynema nodinauti gen. n. sp. n., male, holotype, total view.

FIGURE 2. Bathynema nodinauti gen. n. sp. n., male, holotype. A, anterior end, lateral view; B, anterior end laterally, surface view; C, anterior end, frontal view; D, posterior end; E, spicula.