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 : 6-7

Mesocoelium meggitti— USNPC 0 90335.00

( Figure 2, Table 1)

Host: Hemidactylus turcicus (Linnaeus) , Mediterranean house gecko ( Squamata : Gekkonidae ).

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

Description: Based on one specimen: Body 2,808 by 572; forebody 700 long, representing 25% of body length. Mouth subterminal; oral sucker oval, 290 by 260; prepharynx short; pharynx oval, 122 by 143; ratio of pharynx width to oral sucker width 1:1.8; esophagus 90 long; ceca terminating past posterior margin of ovary, occupying at least 26% of postovarian space. Ventral sucker oval, situated in 1/3 of body, 198 by 192; ratio of ventral sucker width to oral sucker width 1:1.4. Testes oblique; right testis 190 by 200; left testis 190 by 150. Genital pore median, located immediately anterior to midlevel of esophagus. Cirrus sac 203 long, representing 7% of body length. Ovary oval, 170 by 160; postovarian space 1,742 long, representing 62% of body. Uterus extensive, filling most of hindbody. Vitelline follicles distributed in lateral fields from level of posterior margin of pharynx to past posterior margin of ovary. Eggs 37 (31–42) by 21 (18–23). Excretory system not visible.

Remarks: Although the oral sucker and surrounding area in this specimen is slightly damaged, pulling the oral sucker to the left, the genital pore placement seems to have remained unaffected. Additionally, the gonads are pulled into a tight, overlapping cluster at the level of the ventral sucker.

In this specimen, the ceca surpass the ovary posteriorly, the genital pore is prebifurcal, but 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 ovary posteriorly compared with terminating well short of anterior margin of the ovary, a larger body length (2,808 compared with 1,260–2,410), a shorter forebody (700; 25% of body length compared with 970; 36%), a narrower oral sucker (260 compared with 382), and a narrower ventral sucker (192 compared with 344).

This specimen is consistent with M. meggitti by having a genital pore that is median and located anterior to the midlevel of the esophagus, vitelline fields that surpass the ovary posteriorly, a similar ratio of the ventral sucker width to the oral sucker width (1:1.4 compared with 1:1.5), a similar ratio of pharynx width to oral sucker width (1:1.8 compared with 1:2.0), a similar percentage of the distance that the ceca extend into the postovarian space (at least 26% [cecal ends not visible] compared with 28% of the postovarian space), and a similar egg length (37 [31–42] compared with 36 [34–37]). This specimen differs from M. meggitti as redescribed by Dronen et al. (2012) by having a shorter body length (1,070–2,110 compared with 2,808), and a slightly wider egg (18–23 compared with 23–26).