Mesocoelium

Calhoun, Dana M. & Dronen, Norman O., 2012, A reevaluation of specimens of Mesocoelium monas (Platyhelminthes: Digenea: Mesocoeliidae) from the Natural History Museum, UK and the United States National Parasite Collection, USA, Zootaxa 3589, pp. 1-29 : 9

Mesocoelium meggitti— NHMUK 1980.11. 12 1-3

(Figure 4, Table 1)

Host: Bufo marinus (Linnaeus) , cane toad ( Anura ; Bufonidae ).

Locality: Jamaica. (Introduced)

Description: Based on one specimen: Body 1,768 by 806; forebody 520 long, representing 29% of body length. Mouth subterminal; oral sucker, oval, 220 by 221; prepharynx absent; pharynx oval, 83 by 99; ratio of pharynx width to oral sucker width 1:2.2; esophagus 98 long; ceca terminating well past posterior margin of ovary, occupying 28% of postovarian space. Ventral sucker oval, situated in posterior of anterior 1/3 of body, 160 by 170; ratio of ventral sucker width to oral sucker width 1:1.3. Testes slightly oblique; right testis 120 by 143; left testis 130 by 120. Genital pore median, located near posterior margin of pharynx. Cirrus sac 155 long, representing 9% of body length. Ovary oval, 140 by 130; postovarian space 990 long, representing 56% of body length. Uterus extensive, filling hindbody. Vitelline follicles distributed in lateral fields from posterior margin of oral sucker to level of ceca ends posteriorly. Eggs 35 (34–39) by 20 (18–22). Excretory system not visible.

Remarks: This specimen appears to have been overly compressed at the time of fixation: the shape of the body is distorted, the pharynx is twisted, the cecal bifurcation is displaced to the left, and the cirrus sac appears unusually wide.

Although this specimen has ceca that surpass the ovary posteriorly and a prebifurcal genital pore, the genital pore is median rather than submedian, precluding its assignment to the monas body type. Based on these characters, this specimen is assigned to the mesembrinum body type. This specimen further differs from M. monas by having vitelline fields that surpass the cecal ends posteriorly compared with terminating well short of cecal ends, a smaller forebody (520 compared with 970), a narrower oral sucker (221 compared with 382), a narrower pharynx (83 compared with 138), and a narrower ventral sucker (170 compared with 344).

This specimen is consistent with M. meggitti by having a prebifurcal genital pore that is located immediately posterior to the pharynx, a similar ratio of ventral sucker width to oral sucker width (1:1.3 compared with 1:1.3–1:1.5), a similar ratio of pharynx width to oral sucker width (1:2.2 compared with 1:2.0), a similar body length (1,768 compared with 1,070–2,110), and a similar egg length (34–39 compared with 33–37).