Description of a new ascarid species in elasmobranchs from Taiwan Strait.

Abstract

A new ascarid of elasmobranchs, Terranova amoyensis sp. n., is described from the intestine of the red stringray, Dasyatis akajei (Müller and Henle), from Taiwan Strait. This is the second report from this genus with a gubernaculum in fish. The new species differs from its congeners mainly in the following combination of characters: the 3 lips are unequal in size and different in shape, i.e., the subventral lips are asymmetric bilaterally and larger than the dorsal lip; the latter lip is bilaterally symmetrical. The ventriculus is spherical, and the cecum is short relative to the esophagus. Spicules are unequal in size, 1.48 mm long for the right spicule and 1.34 mm for the left spicule, or 4.3 and 3.9% of body length, respectively. Nineteen pairs of caudal sessile papillae (excluding phasmids) are present, of which 13 pairs are precloacal; pairs 14 and 15 lie close together on either side of the cloaca, composing ad-cloacal papillae (the pair near the tail end are twins). The remaining 4 pairs of postcloacal papillae form a group near the tail tip (pair 18 also twins and near the phasmids). The gubernaculum is I-shaped. The excretory pore is located on top of a coniform prominence whose location is just behind or between the bases of the 2 subventral lips. The vulva is prominent at one-third of the anterior part of the body; the distance from the vulva opening to the anterior body end is 17.4 mm (13.61-21.41), 26.8% (25.14-28.93%) of the body length.