Comparative ultrastructure of the pharynx simplex in turbellaria

Morphology and ultrastructure of the pharynx in Solenofilomorphidae (Acoela)

“…Like Doe (1981), we confirm Crezée's (1975) observation that the pharyngeal cilia are generally of the same structure and thickness as the epidermal cilia, even if their relative length varies between the genera (see below).…”

“…This similarity, however, has to be interpreted as an analogy because of striking differences in other pharyngeal characters and considering the phylogenetic distance between these taxa. Significantly, the relative position of circular and longitudinal muscle layers in the anterior pharynx of our specimens is the reverse of that described by Crezée (1975) and Doe (1981). Only in the posteriormost part of the pharynx of our Solenofilomorpha species, specifically at the funnel-like posterior sphincter, are the circular muscle fibers adluminal.…”

“…When contracting, these muscles may act to widen the mouth opening and at the same time protruding the pharynx toward or even through the mouth. A similar configuration with longitudinal muscles bypassing the mouth is found in the pharynx simplex of the catenulid Stenostomum leucops (see Hooge, 2001) and the pharynx simplex coronatus of Macrostomida and Haplopharyngida (Doe, 1981). This similarity, however, has to be interpreted as an analogy because of striking differences in other pharyngeal characters and considering the phylogenetic distance between these taxa.…”

“…For Solenofilomorpha funilis, details on the sensory cilia are lacking but receptor cells "which appear to be monociliated" occur along the lateral walls of the mouth (Doe, 1981).…”

New acoels (Acoela, Acoelomorpha) from North Carolina

“…Acoels from North Carolina have been used in many important investigations of flatworm ultrastructure (e.g., Tyler 1973, Crezée 1975, Crezée & Tyler 1976, Doe 1981, Smith & Tyler 1985, Rieger et al 1991, and eight of the 40 acoel species known from the Atlantic coast of North America were originally described from North Carolina (see Hooge & Tyler 2003), including four species of the genus Solenofilomorpha (see Crezée 1975). There are many more acoels in North Carolina that have yet to be described, and we found that the shallow subtidal of Lockwoods Folly Inlet, Oak Island, North Carolina is especially abundant with acoel flatworms.…”