Mesocoelium cameroonensis Saoud 1964
Creators: name: Dronen, Norman O.
name: Calhoun, Dana M.
name: Simcik, Steven R.
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Trematoda
Plagiorchiida
Mesocoeliidae
Mesocoelium
Mesocoelium cameroonensis

description: Mesocoelium cameroonensis   
(Figure 9; Table 14)  
 Definitive host: Causus rhombeatus (Lichtenstein), Rhombien or demon night adder (Squamata: Scincidae).   
 Locality: Ghana.   
 Site: Intestine.   
 Specimens examined: BMNH 1969.12.3.   
 Redescription: Based on four specimens. With characteristics of genus. Body mesembrinum type, small, oval, spinose, 1,833 (1,750 –1,975) by 1,054 (900–1,206); body spines 20–22 long; forebody 478 (470–515), 26–26% of body length. Mouth slightly subterminal; oral sucker subspherical to spherical, 355 (295–375) by 373 (290–380); prepharynx short, nearly absent; pharynx spherical to subspherical, wider than long, 85 (80–93) by 125; esophagus not visible; cecal bifurcation near midlevel of forebody; ceca surpassing ovary posteriorly, terminating near midlevel of hindbody, occupying 24–28% of postovarian space. Ratio of widths of oral sucker and pharynx 1:3.9 (1:3.8–1:4.3). Ventral sucker located anterior to midlevel of body, smaller than oral sucker, 288 (271–320) by 327 (290–370). Ratio of sucker widths 1:1.2 (1:1.1–1:1.3).   
Testes smooth, diagonal, situated at level of ventral sucker. Right testis 300 (205–380) by 310 (298–331); left testis 300 (215–330) by 300 (280–317). Cirrus sac situated between pharynx and ventral sucker, enclosing short cirrus, reduced pars prostatica, short ejaculatory duct surrounded by prostate cells, and bipartite seminal vesicle, 195 (175–225, 6–11% of body length) by 74 (69–78). Genital pore near anterior margin of pharynx, prebifurcal, median.  
Ovary smooth, posttesticular, situated short distance posterior to right or left testis, 153 (109–178) by 175 (145–205), removed from posterior end by some distance; postovarian space 1,338 (1,150 –1,525) long, 58–87% of body length. Ratio of width of ovary to mean width of testes 1:1.7 (1:1.5–1:1.9). Seminal receptacle spherical, located immediately sinistral and slightly posterior to ovary. Laurer’s canal present, opening not observed. Vitelline fields distributed along ceca from level of oral sucker posteriorly to near midlevel of postovarian space, surpassing cecal ends; vitelline follicles 46 (25–68) by 34 (30–38) (n = 20). Uterus largely postacetabular, filling most of hindbody. Eggs operculate, 39 (35–42) by 23 (20–28) (n = 30).  
Excretory vesicle Y-shaped, with poorly developed arms; excretory pore slightly subterminal.  
 Remarks: These specimens (BMNH 1969.12.3) have moderately long ceca, and a genital pore that is prebifurcal and median, placing them in the mesembrinum body type. The posterior extent of the vitelline fields surpass the cecal ends posteriorly, the gonads overlap the area of the ventral sucker, the genital pore opens near the level of the anterior margin of the pharynx, the ratio of the width of the pharynx to the width of the oral sucker is 1:3.8–1:4.0, ceca occypying 24–28% of length of postovarian space, and the eggs are 35–42 long placing them in M. cameroonensis. These specimens are larger than those reported by Saoud (1964) in the original description of this species (1,750 –1,975 long compared to 416–640) and have a more extensive postovarian space (1,150 –1,525 long comprising 58–87% of the body length compared to 199 comprising 38% of the body length) that is more heavily ladened with eggs, suggesting a more mature or higher state of development. With the exception of a somewhat smaller ratio of the width of the ventral sucker to the width of the oral sucker (1:1.1–1.3 compared to 1:1.9), the remaining comparative characteristics of these specimens generally conform to those of M. cameroonensis as originally described (Table 14) and although they were collected from a snake (the Rhombien demon night adder) rather than a frog (the sharp-nosed frog) they were collected from the same general geographical region as the type locality for the species (Ghana compared to Cameroon). We do not consider the slight difference in sucker ratios to be sufficient enough reason to separate the BMNH specimens from the original species. It should be noted that both the specimens from Ghana and the specimen represented in Figure 2 of the original description are contracted collapsing the esophagus and likely displacing the genital pore more anteriorly than normal. The genital pore in this species likely would appear a little more posterior in heat fixed specimens where slight coverslip pressure was employed.
description: Published as part of Dronen, Norman O., Calhoun, Dana M. & Simcik, Steven R., 2012, Mesocoelium Odhner, 1901 (Digenea: Mesocoelidae) revisited; a revision of the family and re-evaluation of species composition in the genus 3387, pp. 1-96 in Zootaxa 3387 (1) on page 50, DOI: 10.11646/zootaxa.3387.1.1, http://zenodo.org/record/5253926