A New Species of Westella (Trematoda: Opisthogoniminae) from a Mexican Snake

Abstract

Westella tabascensis sp. n. (Trematoda: Opisthogoniminae) from the mouth of a snake (Coniophanes quinquevittatus) from Tabasco, Mexico, is described. In July 1958, seven specimens of an apparently undescribed species of Westella were recovered from the oral cavity of a snake (Coniophanes quinquevittatus) in the Mexican state of Tabasco. Six were prepared as whole mounts, and the seventh was serially sectioned. The measurements in the diagnosis are of the holotype followed by the size ranges in parentheses. All measurements are in millimeters. Westella tabascensis sp. n. Figure 1 Host: Coniophanes quinquevittatus (Dumbril, Bibron, and Dumbril). Location: Oral cavity. Locality: 15 miles south of Villahermosa, Tabasco, Mexico. Holotype: USNM Helm. Coll. Paratypes: Helm. Coll. Instituto de Biologia, Mexico, D. F.; Dept. of Zoology, Louisiana State University; author's collection. Diagnosis: Body broadly rounded anteriorly, tapering sharply posteriorly; 2.2 (1.8 to 2.34) long, 1.1 (0.85 to 1.1) in maximum width at level of pharynx. Oral sucker subterminal, 0.456 (0.32 to 0.48) long, 0.47 (0.35 to 0.47) wide. Prepharynx moderately long. Length of pharynx 0.152 (0.15 to 0.165) width 0.216 (0.15 to 0'.22) at anterior margin, tapering posteriorly. Esophagus very short. Intestinal ceca extend to near posterior end of body.. Acetabulum 0.27 (0.248 to 0.27) long by 0.318 (0.234 to 0.318) wide. Acetabulo-oral sucker ratio, 1:1.5. Testes spherical, diagonal, in posterior portion or middle third of body. Anterior testis 0.242 (0.23 to 0.30) long, 0.292 (0.25 to 0.292) wide. Posterior testis 0.254 (0.23 to 0.30) by 0.33 (0.25 to 0.33). Cirrus sac anterosinistral to acetabulum, long, slender, 0.445 (0.42 to 0.55) in length by 0.051 (0.05 to 0.068) in maximum diameter, with angular bend anteriorly; contains small seminal vesicle and prostatic cells. Genital aperture immediately posterior to acetabulum, somewhat to left of midline. Ovary 0.292 (0.26 to 0.292) long, 0.254 (0.234 to 0.26) wide; in acetabular region or slightly preacetabular. Small seminal receptacle and ootype posterior to ovary. Vitelline follicles about 0.064 (0.027 to 0.095) in diameter, dorsally located in cecal and intercecal zones, from level of pharynx to posterior margin of testes. Uterus fills intercecal space posterior to acetabulum. Eggs numerous, 0.012 to 0.016 X 0.024 to 0.026.