Mesocoelium meggitti Bhalerao 1927
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 meggitti

description: Mesocoelium meggitti   
(Figures 10–21; Table 15)  
 Definitive hosts: Eleutherodactylus planirostris Cope, greenhouse frog (Anura: Eleutherodactylidae); Causus rhombeatus, Rhombien or demon night adder (Squamata: Scincidae); Bufo marinus, the cane toad (Anura: Bufonidae); Ctenonotus stratulus (Cope), Puerto Rican spotted anole or barred anole (Squamata: Polychrotidae); Anolis cristatellus Duméril &Bibron, Puerto Rican crested anole (Squamata: Polychrotidae); Hemidactylus turcicus (Linneaus), Mediterranean house gecko (Squamata: Gekkonidae); Hemidactylus brooki Gray, Brook’s wall gecko (Squamata: Gekkonidae).   
 Localities: Louisiana, USA; Panama; Puerto Rico, USA; Ghana.   
 Site: Intestine.   
 Specimens examined: BMNH 1976.1.7 (Ghana); HWML 1570 (Panama); SLU-7a and USNPC 090333.00 (Louisiana, USA); USNPC 090928.00 and 073287.00 (Puerto Rico, USA); SLU-13 and USNPC 090335.00 (Louisiana, USA).   
 Redescription: Based on 13 specimens. With characteristics of genus. Body mesembrinum type, relatively large, posteriorly attenuated, body tapering markedly posteriorly, nearly club-shaped, forebody wider than hindbody, spinose, 2,823 (1,625 –4,975) by 663 (546–950); body spines 9–13 long; forebody 714 (410–1,105) long, 21–35% of body length. Oral sucker spherical to subspherical, 295 (205–315) by 283 (198–320), preoral lobe present, not always obvious, mouth opening anterior from center of sucker, nearly terminal; prepharynx short, 0–10 long; pharynx subspherical to spherical, wider than long, 105 (80–130) by 115 (85–145); esophagus 96 (45–170) long; cecal bifurcation immediately preacetabular; ceca surpassing ovary posteriorly, terminating near midlevel of hindbody, occupying 29–47% of postovarian space. Ratio of width of oral sucker and pharynx 1:2.2 (1:2.0–1:2.5). Ventral sucker located anterior to midlevel of body, smaller than oral sucker, 174 (138–200) by 169 (133–220). Ratio of sucker widths 1:1.5 (1:1.1–1:1.7).   
Testes smooth, diagonal to nearly side by side, situated at level of ventral sucker. Right testis 180 (75–350) by 168 (105–290); left testis 176 (80–370) by 154 (95–290). Cirrus sac situated between pharynx and ventral sucker, enclosing short cirrus, reduced pars prostatica, short ejaculatory duct surrounded by prostate cells, and tripartite seminal vesicle, 219 (103–319, 6–10% of body length) by 61 (33–95). Genital pore immediately postpharyngeal, prebifurcal, median.  
Ovary smooth, posttesticular, situated short distance posterior to right or left testis, 172 (100–270) by 170 (88–254), removed from posterior end by some distance; postovarian space 1,783 (750–3,450) long, 50–69% of body length. Ratio of width of ovary to mean width of testes 1:1.0 (1:0.7–1:1.2). Seminal receptacle spherical, located immediately sinistral and slightly posterior to ovary. Laurer’s canal present, opening on dorsal surface. Vitelline fields distributed along ceca from level of pharynx posteriorly to near midlevel of postovarian space, terminating near to, or surpassing cecal ends; vitelline follicles 69 (15–140) by 53 (18–70) (n = 30). Uterus largely postacetabular, filling most of hindbody. Eggs operculate, 35 (31–40) by 22 (19–29) (n = 40).  
Excretory vesicle Y-shaped, with poorly developed arms; excretory pore slightly subterminal.  
 Remarks: These specimens (BMNH 1976.1.7 [Ghana]; HWML 1570 [Panama]; SLU-7a, USNPC 090333.00 [Louisiana, USA]; USNPC 090928.00 [Puerto Rico, USA]; USNPC 073287.00 [Puerto Rico, USA]; SLU-13, USNPC 090335.00 [Louisiana, USA]) 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 terminate near to, or surpass the cecal ends posteriorly; the gonads overlap the area of the ventral sucker; the genital pore is immediately postpharyngeal, opening above the midlevel of the esophagus and the body is markedly attenuated posteriorly (nearly club-shaped) so that the forebody is wider than the hindbody, placing these specimens in M. meggitti. These specimens conform to the original description of M. meggitti in all respects (Table15). This species appears to be unique by having a tripartite seminal vesicle. Neither Bhalerao (1927) in the original description of M. meggitti nor Pereira & Cuocolo (1940) in the original description of M. travassosi (considered herein as a synonym of M. meggitti) fully described the nature of the seminal vesicle; however, in Figure 1 of the original description of M. sibynomorphi the seminal vesicle appears generally similar to the seminal vesicle in the specimens we examined. It appears that this species was introduced into the New World where it has become extensively distributed around the area of the Gulf of Mexico and the Caribbean. We have included Figure 18 (USNPC 1976.1.7) as what we consider to be an example of the possible impact of fixation without relaxing specimens and heat fixing them under slight coverslip pressure on body shape. Although this specimen is tapered posteriorly and the forebody is wider than the hindbody, it does not have the distinctive clavate shape of the species. However, it conforms to M. meggitti in all other respects and has the tripartite seminal vesicle that is characteristic of the species.
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 52, DOI: 10.11646/zootaxa.3387.1.1, http://zenodo.org/record/5253926