Mesocoelium danforthi, Hoffman, 1935

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 : 70

Mesocoelium danforthi

( Figures 28–29; Table 17)

Definitive hosts: Anolis lineatopis Gray, Jamaican gray anole or striped foot anole ( Squamata : Polychrotidae ); Bufo marinus Linnaeus , the cane toad ( Anura : Bufonidae ).

Localities: Jamaica, USA; Panama USA.

Site: Intestine.

Specimens examined: BMNH 1980.12.3.19-22 ( Jamaica); USNPC 0.569 38.00 ( Panama).

Description of specimens: Based on four specimens. With characteristics of genus. Body monas type, small, oval, spinose, 1,907 (1,288 –2,125) by 764 (463–925); body spines 9–11 long; forebody 524 (465–550) long, 26–36% of body length. Mouth slightly subterminal; oral sucker spherical to subspherical, 292 (220–380) by 250 (225–265); prepharynx short; pharynx subspherical to spherical, wider than long, 88 (65–100) by 96 (70–110); esophagus 46 (30–58) long; cecal bifurcation near midlevel of forebody; ceca reaching posterior to ovary terminating near midlevel of hindbody, occupying 27–32% of postovarian space. Ratio of widths of oral sucker and pharynx 1:2.7 (1:2.4–1:3.2). Ventral sucker located anterior to midlevel of body, smaller than oral sucker, 170 (130–190) by 180 (120–220). Ratio of sucker widths 1:1.5 (1:1.3–1:1.9).

Testes smooth, diagonal, situated at level of ventral sucker. Right testis 154 (78–230) by 167 (92–250); left testis 163 (105–220) by 165 (105–225). 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, 159 (145–173, 8–11% of body length) by 43 (38–52). Genital pore near posterior margin of pharynx, prebifurcal, submedian.

Ovary smooth, posttesticular, situated short distance posterior to right or left testis, 173 (125–220) by 160 (90–230), removed from posterior end by some distance; postovarian space 1,618 (645–1,303) long, 50–62% of body length. Ratio of width of ovary to mean width of testes 1:0.9 (1:1.0–1:1.0). 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 hindbody, terminating near to, or surpassing cecal ends; vitelline follicles 43 (21–80) by 41 (20–70) (n = 20). Uterus largely postacetabular, filling most of hindbody. Eggs operculate, 35 (32–38) by 20 (18–23) (n = 30).

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

Remarks: These specimens (BMNH 1980.12.3.19-22; USNPC 056938.00) have moderately long ceca, and a genital pore that is prebifurcal and submedian, placing them in the monas 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 body is oval, widest near midbody; the genital pore is located near posterior margin of the pharynx; the ceca are moderately long, terminating near midlevel of postovarian space and occupying 27–32% of the postovarian space; and the maximum egg size is 38 by 23, placing it in M. danforthi . These specimens conform in all respects to the type series of M. danforthi (Table 17), but appear to have slightly larger body spines (9–11 long compared to 4–5 from only a few remaining, possibly damaged, spines of a paratype). It should be noted that these specimens are much less contracted than those used in the original description by Hoffman (1935) (based on Figure 13 ) or those used in the study on growth and morphological variation of M. danforthi by Mettrick & Dunkley (1968) (based on Figure 1 and the nature of the esophagus profiled in the sections in Figure 2 , illustrations C and D). These specimens (BMNH 1980.12.3.19-22; USNPC 056938.00) show the presence of a short esophagus (30–58 long).

Figures

FIGURES 13–14. Mesocoelium meggetti. 13. Ventral view of adult (USNPC 090928.00). 14. Ventral view of adult (USNPC 073287.00).

FIGURES 1–3. Mesocoelium brevicaecum (BMNH 1973.5.25.1-11). 1. Ventral view of adult. 2. Composite drawing of area between cecal bifurcation and ventral sucker showing placement of genital pore, uterus and seminal vesicle, ventral view. 3. Composite drawing of area of oötype, ventral view. Abbreviation used in figures: C=cecum; E=egg; Ev=excretory vesicle; G= genital pore; L= Laurer’s canal; M=Mehlis’ glands; OV=ovary; P=pharynx; SR= seminal receptacle; SV=seminal vesicle; T=testis; U=uterus; VD=vitelline duct.