Mesocoelium zhejiangensis, Xida & Puzhu, 1986

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, Zootaxa 3387 (1), pp. 1-96 : 43-48

Mesocoelium zhejiangensis

( Figure 7 ; Table 14)

Definitive host: Listed as being collected from Rana margaritas from Gaungdong Province; however, the only species of raniid frog from Guangdong Province in the People’s Republic of China we could find is Rana zhenhaiensis Ye, Fei & Matsui , the Zhenhai or Tsushima brown frog ( Anura : Ranidae ).

Locality: Qaungdong Province, the People’s Republic of China.

Site: Intestine.

Specimens examined: BMNH 1997.9.18. 8.

Redescription: Based on four specimens. With characteristics of genus. Body zhejiangensis type, small, elongate with somewhat tapered posterior end, spinose, 2,135 (1,875 –2,388) by 878 (738–1,150); body spines 6–8 long; forebody 655 (560–686) long, 30–32% of body length. Mouth slightly subterminal; oral sucker subspherical to spherical, 248 (190–275) by 256 (220–295); prepharynx short, nearly absent; pharynx spherical to subspherical, wider than long, 81 (48–108) by 102 (73–120); esophagus 85 (35–170) long; cecal bifurcation near midlevel of forebody; ceca short, terminating anterior to level of ovary. Ratio of widths of oral sucker and pharynx 1:2.8 (1:2.3–1:3.0). Ventral sucker located in anterior ½ of body, smaller than oral sucker, 187 (163–200) by 188 (175–200). Ratio of sucker widths 1:1.4 (1:1.3–1:1.5).

Testes smooth, side by side to slightly diagonal, situated at level of ventral sucker. Right testis 134 (130–175) by 173 (150–200); left testis 160 (150–200) by 180 (160–200). Cirrus sac situated between cecal bifurcation and ventral sucker, enclosing short cirrus, reduced pars prostatica, short ejaculatory duct surrounded by prostate cells, and bipartite seminal vesicle, 228 (190–235, 8–15% of body length) by 73 (65–91). Genital pore bifurcal, median. Ovary smooth, posttesticular, situated immediately posterior to right or left testis, 180 (140–230) by 193 (160–220), removed from posterior end by some distance; postovarian space 1,226 (1,040 –1,425) long, 54–60% of body length. Ratio of width of ovary to mean width of testes 1:1.0 (1:0.8–1:1.3). 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 level of ventral sucker, terminating immediately anterior to cecal ends; vitelline follicles 53 (35–103) by 49 (42–90) (n = 25). Uterus largely postacetabular, filling most of hindbody. Eggs operculate, 47 (43–51) by 25 (22–27) (n = 40).

Excretory vesicle Y-shaped, with poorly developed arms; excretory pore slightly subterminal.

Remarks: These specimens (BMNH 1997.9.18.8) have short ceca, and a genital pore that is bifurcal and median, placing them in the zhejiangensis body type. We consider these specimens to represent M. zhejiangensis , but these specimens differ from the original description by having a somewhat smaller ratio of the width of the ventral sucker to the width of the oral sucker (1:1.3–1:1.5 compared to 1:1.8–1:2.3). Like the specimens used in the original description by Xida & Puzhu (1986), the four specimens we examined (BMNH 1997.9.18.8) were also from a frog (probably Rana zhenhaiensis , but reported as Rana margaritas ) from south-eastern People’s Republic of China where M. zhejiangensis was originally described, and we feel that the difference seen in the sucker ratio is likely sample size related, a product of fixation or possibly due to host-induced variability.

Figures

FIGURE 7. Mesocoelium zhejiangensis (BMNH 1977.9.18.8). 7. Ventral view of adult.