This species was first reported by ISHII (1916) under the name of Filaria cyprini. Molphological studies were made on 16 mature female nematodes gathered form the subcutaneous tissue of two year old carp, Cyprinus carpio, in Shimane prefecture in April and May, 1970, and led to the following conclusion.
This species should be combined with Philometroides based on the RASHEED opinion (1963) in respect of its cuticular condition and should be, morphologically and ecologically, separated from the other species of the genus Philometroides: P. anguillae (ISHII, 1916), P. maplestonei (TRAVASSOS, ARTIGAS and PEREIRA, 1929), P. masu (FUJITA, 1940), P. plectroplites (JOHNSTON and MAWSON, 1940), P. sanguinea (Run., 1819) and P. seriolae (ISHII, 1931), and some closly related species bearing cuticular bosses on the surface of body; that is Philometra carassii (ISHII, 1931) and P. nodulosa THOMAS, 1929.
Description: Body slender and almost uniformly broad except at extremities, 9.012.2 cm long, 0.62.0.90 mm broad; cuticle with numerous minute, irregularly distributed lobelike structures. Head bluntly rounded with four cuticular thicknings, but without any cephalic papillae. Mouth triangular formed with three anterior swellings of esophagus (0.0760.082 mm broad); esophagus, 2.89 3.32 mm long, 0.026 0.039 mm broad, with greatly developed esophageal gland, 0.16 0.21 mm maximum broad, which beginning at about level of nerve ring, 0.210.26 mm from head end. Intestine, about 0.29mm broad, gradually tapered and finally become a solid cord attached to body wall at tail and. Uterus voluminous, occupding most of body cavity; a pair of ovary short and uncoiled, 0.3960 mm Iong, 0.100.18 mm broad. Vulva and anus atrophied. Tail bluntly pointed with two or three cuticular thicknings, or without any shield.
