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.