STRONGYLID PARASITES OF DONKEYS IN PEKING. IP
K'UNG FAN-YAO & YANG NIAN-HE (Peking Agricultural College)
The present paper is the second part of a series of papers on the ncmatodcs of donkeys in Peking. Eight species belonging to the family Trichonematidae are reported, namely, Trichonema labratum, T. labiatum, T. labiatum var. digitatum, T. coronatum, T. longibursatum, T. mimttum, T. tsengi sp. nov., and Petrovinema peculation.Trichonema tsengi sp. nov.A moderately small species. Male 6.4-7.6mm; maximum breadth 0.275-0.345 mm. Female 6.6-8.4mm; maximum breadth 0.275-0.36mm. The anterior extremity tapers slightly to the head; there is no definite neck. Mouth collar moderately high and is marked off from the rest of the body by a constriction. Circumoral papillae projected forward and are as long as the external leaf-crown. The external leaf-crown composed of about 18 long pointed elements, projecting well beyond the mouth collar. The elements of the internal leaf-crown are about 36 short refractive rods. The region of origin of the elements of the internal leaf-crown extends back to 0.005 mm behind the anterior border of the buccal capsule. Buccal capsule is general long and is somewhat narrower anteriorly than posteriorly. It has a depth of 0.037-0.046 mm in the male, 0,038-0.048 mm in the female, with a maximum breadth of 0.032-0.036 mm in the male and 0.033-0.038 mm in the female at its posterior extremity. The walls are thick and swollen at the posterior end and decrease in thickness anteriorly. Dorsal gutter well developed, and projects far into the buccal capsule, extending nearly to the level of the anterior fourth of the buccal capsule. Length of the oesophagus is 0.276-0.348 mm in the male, and is 0.314-0.407 mm in the female. The breadth of the oesophagus is 0.057-0.067 mm at the anterior extremity, and the greatest breadth is 0.081-0.101mm.Excretory pore and cervical papillae are at about the same level behind the nerve ring, and are 0.247-0.379 mm from anterior extremity. Distance from the extremity to the nerve ring is 0.18-0.23 mm.Posterior extremity, male,-fairly long median lobe; lateral lobes marked off from the dorsal lobe by a shallow notch. Main dorsal ray, measured from point of insertion of the externo-dorsal ray is 0.47-0.555 mm in length. Genital cone is well developed, with about 16 processes on its posterior surface.Posterior extremity, female,-straight. Distance of anus from tip of the tail is 0.0875-0.125mm. Distance between anus and vulva is 0.063-0.11mm. Vagina is 0.215-0.39mm in length.Relationship-This worm is more closely allied to T. calkatum than to either of the other species in the calkatum group (of Ihle), but it differs from T. calkatum in the shape of the buccal capsule, in its much greater depth of the buccal capsule in proportion to its width, in the shape of the wall of the buccal capsule, in the number of elements of the external leaf-crown, and in the different shape of the distal ends of the external leaf-crown elements.Host-Equus asinus. Locality-large colon. Place of distribution-Peking.