Trophomera minutissima, 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 : 183

Trophomera minutissima sp. n.

Fig. 5 ; Table 2

Type material: Holotype: one gravid female, collection number MNHN-BN495 .

Type locality: 14°02.86’N, 130°05.35’W, 5040 m depth, 30.05.2004, multicorer #6, corer #2.

Etymology: From Latin minutissima (smallest).

Description: Female. Body cylindrical, with thickest body part at anterior half of body; anterior and posterior ends rounded. Transverse cuticular striation along whole body length hardly discernable using light microscope. Cuticle thickness 2.5 µm at anterior tip, 1.5 µm at mid-body region, and 3 µm at posterior tip. Amphidial apertures pore-like, 1 µm in diameter, located in 0.81 c.b.d. from anterior and. Amphidial fovea 3 µm in diameter visible under cuticle. Four submedian, setiform papillae 1.5 µm long. Mouth opening absent. Pharynx a non-muscular string devoid of an internal lumen. Cardia absent. Midgut, an oligocellular trophosome without visible internal lumen and obviously consisting of 1 row of cells. Numerous big, hyaline granules within trophosomal cells. Borders between trophosomal cells distinct. Anus and rectum present. Female reproductive system didelphic, amphidelphic, occupying approximately 1/3 body length. Ovaries reflected, 100–110 µm long, containing several tens of oocytes. Neither spermatheca, nor spermatozoa, nor vulvar glands observed. Hyaline ring representing a circular vaginal sphincter visible around vagina. Mature eggs in oviducts and uterus approximately 17 µm in diameter. Caudal glands absent.

Host unknown.

Male, juvenile stages unknown.

Differential diagnosis: The female of Trophomera minutissima sp. n. shows resemblance to females of T. bathycola ( Rubtzov, 1980) , T. edouardensis (Petter, 1983) ( Petter 1983b) , and T. minuta ( Petter, 1987) by its reflected ovary and rounded tail without any process but differs from these species by its shorter body (0.9 mm vs. 2.3, 4.1, and 9.4 mm respectively). It is the smallest species in the genus Trophomera .

Figures

FIGURE 5. Trophomera minutissima sp. n., female, holotype. A, total view; B, genital system; C, cephalic end, lateral view; D, posterior end. Abbreviation: a = amphid.