Turbellarian taxonomic database

Acoela Actinoposthiidae Notes

Hooge MD 2001 (citation) - "Childia groenlandica posesses not only a unique pattern of musculature (Figs. 6,7)
but the layering of these muscles is also unique among acoels in that the relative positions of the
subepidermal body-wall muscle fibers are reversed, with longitudinal muscle fibers lying outside of inner
circular fibers, a condition first recognized by Luther (1912) (citation). These features, along with its
unusual paired male copulatory apparatus, suggests that the Childiidae as it is presently known is 
polyphyletic. Additional endorsement for polyphyly comes from preliminary ultrastructural and
immunocytochemical studies that sugges the sclerotized copulatory structures used to unite the group are
nonhomologous among several taxa (Raikova et al., 2001) (citation). I propose leaving Childia groenlandica
as the sole occupant of Childiidae and creating a new family, Actinoposthiidae, for the other childiid taxa."

Hooge MD, Haye P, Tyler S, Litvaitis MK, Kornfield I  2002 (citation)- Phylogenetic relationships using 18S
rDNA, and morphological characters of sperm and body-wall musculature.- "The unique nature of C. groenlandica
led Hooge 2001 (citation) to remove the other species in the Childiidae to a new family, the Actinoposthiidae.
The gene tree supports this taxonomic revision; however, some further changes may be necessary, inasmuch
as members of the actinoposthiid genus Paraphanostoma also have circular muscles (Westblad, 1942) (citation)."
Tekle YI, Raikova OI, Ahmadzadeh A, Jondelius U 2005 (citation) - Found the monophyly of Childia and Paraphanostoma to be supported by molecular and morphological data. Paraphanostoma synonymized with Childia; all former members of Paraphanostoma transferred to Childia.
Citing unpublished evidence that species outside the Actinoposthiidae---namely Haplogonaria syltensis Dorjes, 1968, and Actinoposthia biaculeata Faubel, 1974---have longitudinal muscles outermost in the body wall, a character Hooge (2001) (citation) cited as a primary reason for distinguishing Childia groenlandica from other childiids, Faubel & Warwick (2005) (citation) ignored the erection of this family by Hooge (2001). See, however, Tekle et al. (2005) (citation) for molecular-sequence data supporting the distinct position of Childia and its subsequent transfer to the Mecynostomidae.

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