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 : 19-20

Mesocoelium cf monodi— USNPC 0 90334.00

( Table 3 )

Host: Anolis carolinensis (Voigt) , green anole ( Squamata : Polychrotidae ).

Locality: Metairie, Louisiana; 29 35’ N 90 61’ W. (Native)

Description: Based on one specimen: Body 1,950 by 646; forebody 550, representing 28% of body length. Mouth subterminal; oral sucker subspherical, 260 by 250; prepharynx absent; pharynx subspherical, 99 by 125; ratio of pharynx width to oral sucker width 1:2.0; esophagus not visible; ceca surpassing ovary posteriorly, occupying at least 35% (ends of ceca not visible) of postovarian space. Ventral sucker subspherical, situated in anterior 1/3 of body, 208 by 208; ratio of ventral sucker width to oral sucker width 1:1.2. Testes subspherical, opposite to slightly oblique; right testis 150 by 160; left testis 160 by 150. Genital pore submedian, located at level of posterior 1/3 of pharynx. Cirrus sac not visible. Ovary oval, 130 by 150; postovarian space 1,092 long, representing 56% of body length. Uterus extensive, filling hindbody. Vitelline fields distributed in lateral fields from level of posterior margin of oral sucker to level of posterior portion of 1/3 of body. Eggs 38 (36–39) by 22 (21–23). Excretory system not visible.

Remarks: This specimen was contracted pulling the pharynx anteriorly into the oral sucker. The poor quality of this specimen limited our observations of many structures (e.g. ceca ends, cirrus sac, esophagus, excretory system).

Although this specimen has ceca that surpass the ovary posteriorly and a prebifurcal genital pore, and is assigned to the monas body type, it cannot be assigned specifically to M. monas . This specimen differs from M. monas by having vitelline fields that terminate near to the cecal ends compared with terminating well short of the cecal ends, a shorter forebody (550; 28% of body length compared with 970; 53%), and a narrower ventral sucker (208 compared with 300).

This specimen is most consistent with M. monodi by having similar forebody lengths (550; 28% of body length compared with 778; 26%), a similar oral sucker width to ventral sucker width (1:1.2 compared with 1:1.3) and a similar egg size (36–39 by 21–23 compared with 35–38 by 20–23). This specimen can be distinguished from M. monodi by having a shorter body length (1,950 compared with 3,000) and this specimen was collected in a different general geographical areas (Louisiana compared with Cameroon). These differences suggest this specimen likely represents an undescribed species. This appears to be the same species as represented by USNPC 0 90332.00.

Locality Papua New Guinea Louisiana Louisiana

NM=No accurate measurement possible.

Tables

TABLE 3. Comparative measurements, morphometric percentages and morphometric ratios for species of Mesocoelium previously identified as Mesocoelium monas that appear to be Mesocoelium monodi from the Natural History Museum, UK and the United States Parasitology Collection.

Characteristic	M. cf monodi NHMUK 1980.7.14 50-54 n=2	M. cf monodi USNPC 0 90332.00 n=1	M. cf monodi USNPC 0 90334.00 n=1
Body length	2,094 (1,404–2,784)	1,456	1,950
Forebody length	832	460	550
Forebody length as a percentage of body length	40%	32%	28%
Oral sucker width	220 (210–231)	169	250
Pharynx width	91 (78–104)	78	125
Oral sucker width/pharynx width	1:2.5 (1:2.2–1:2.7)	1:2.2	1:2.0
Ventral sucker width	154 (125–182)	143	208
Oral sucker width/ventral sucker width	1:1.5 (1:1.3–1:1.7)	1:1.2	1:1.2
Esophagus length	105 (90–121)	50	NM