MONOGENEANS

 

Monogeneans –

Taxonomy: Kingdom Animalia, Phylum Platyhelminthes, Class Trematoda, Subclass Monogenea

Description: Can be ectoparasites and are the most primitive flukes (Olsen, 1986). They have a posterior holdfast and the adults are small and either oval or circular (Marquardt, Demaree, & Grieve, 2000).

Lifecycle: Direct, an intermediate host is not necessary (Olsen, 1986) and they usually cross-fertilize. (Marquardt, Demaree, & Grieve, 2000).

Pathology: Variable

Location and Lifestage in Frog: Any stage in bladder or mouth (Schmidt, 1992).

Polystomatidae –

Taxonomy: Kingdom Animalia, Phylum Platyhelminthes, Class Trematoda, Order Polyopisthocotylea, Family Polystomatidae

Description: A monogenean, anchor is complex with multiple suckers, clamps, and hooks while the anterior holdfast is simple with few suckers and ducts (Marquardt, Demaree, & Grieve, 2000). About 4 mm long

Lifecycle (by Schmidt & Roberts, 1989): Closely synchronized with its host through hormones; adults lay dormant when frog host hibernate, and when the frog reproduces, the parasite releases its eggs. The next generation of tadpoles is the next generation of hosts for the next generation of parasite.

Pathology: Infected lung tissue becomes inflammatory with epithelial cell vacuolation, interstitial oedema, and an increase of alveolar exudate, leucocytes and fibrous tissue (Tinsley, Cable, & Porter, 2002).

Location and Lifestage in Frog: Gills, nasal cavities, pharynx, esophagus, or bladder at any stage (Olsen, 1986).

A class under the Family Trematoda, monogeneans lack or possess a weakly developed oral sucker. Their posterior end has a large posterior adhesive disk called an “opisthaptor” and it usually has hooks. The anterior and dorsal excretory pores are paired. Monogeneans have a simple life cycle and are mainly found in the epithelial layers (Olsen, 1986).

(Vaucher, 1990)