Redescription of Prosthopycoides lynchi (Ingles, 1936) gen. et comb. n. (Trematoda: Lecithodendriidae)

Abstract

The trematode Brachycoelium lynchi Ingles, 1936, is redescribed and transferred to Prosthopycoides gen. n. This genus differs from Lecithodendrium by having preacetabular testes and prececal vitellaria; from Prosthodendrium by having a pseudocirrus, anterior uterine loops and no genital sinus; and from Pycnoporus by having prececal vitellaria, shorter esophagus, and oval shape. This species is the only member of the subfamily Lecithodendriinae found in amphibians. Ingles (1936) discovered a fluke in the redlegged frog in California and named it Brachycoelium lynchi. Manter (1938) suggested that this worm probably belonged in the genus Lecithodendrium Looss, 1896, and Rankin (1938) followed that suggestion by transferring the species to Lecithodendrium on the basis of the original description and figure. Cheng (1958) studied the type and paratypes deposited in the U. S. National Museum by Ingles and concluded that Rankin (1938) was correct in removing this fluke from Brachycoelium but doubted that Lecithodendrium was the correct genus. Yamaguti (1958) retained this species in Brachycoelium; however, he noted Rankin's proposed change to Lecithodendrium. Dubois (1960, 1961a, b) did not mention this fluke in his revision of the lecithodendriids. After comparing my own specimens with those described by Ingles, I am convinced that this species should be redescribed and a new genus erected to accommodate it. The trematode was found only in Rana aurora although 13 other species of frogs and salamanders were examined in Oregon. Specimens were fixed in Lavdowsky's AFA or Gilson's fluid under slight cover slip pressure and stained with Delafield's hematoxylin. Drawings were made using a Wild drawing apparatus. Measurements were taken from eight egg-bearing adult specimens from two hosts, and are in microns. The average measurement is followed by the range in parentheses. The Received for publication 16 February 1966. * Based in part on a thesis submitted to the Graduate School, Oregon State University in partial fulfillment of requirements for the Doctor of Philosophy degree. t Present address: Dept. of Zoology, Seattle Pacific College, Seattle, Washington 98119. long axis or anterior-posterior measurement is followed by the width measurement. Prosthopycoides gen. n. Diagnosis Lecithodendriidae-Lecithodendriinae. Small, spinous, slightly flattened distomes. Suckers subequal; oral sucker subterminal, mouth subterminal with funnel-shaped opening leading to short prepharynx. Pharynx globular, smaller than oral sucker, surrounded by small peripharyngeal glands. Esophagus about as long as pharynx; ceca very short, widespread. Acetabulum muscular, in posterior half of body. Testes entire, opposite, preacetabular. Pseudocirrus sac intertesticular, curved with distal end turning posteriorly to join genital atrium; genital pore median, ventral, directly anterior to acetabulum; seminal vesicle large, coiled; ejaculatory duct, surrounded by prostatic cell mass, leads from seminal vesicle to form terminal, eversible pseudocirrus (as defined by Pande, 1935 and Dubois, 1960). Ovary entire, intertesticular, dextral or sinistral. Seminal receptacle extending posteriorly from ovary; Laurer's canal arises from seminal receptacle; Mehlis' gland present. Vitelline follicles in a grape-like cluster on each side, posterolateral to oral sucker, anterior to ceca; vitelline duct extends from each cluster to vitelline reservoir between ovary and seminal receptacle. Uterus extensive posterior to acetabulum, anterolateral loops extend to vitellaria. Eggs small, operculate. Excretory pore median; bladder V-shaped, with widespread crura reaching acetabular level. Intestinal parasites of amphibians. Type-species: P. lynchi (Ingles, 1936). Type-host: Rana aurora, red-legged frog. Prosthopycoides lynchi (Ingles, 1936) gen. et comb. n. (Figs. 1-4) Syn. Brachycoelium lynchi Ingles, 1936 Lecithodendrium lynchi (Ingles, 1936) Rankin, 1938