Turbellarian taxonomic database

Crucimusculata Dakuidae Notes

Hooge MD 2003 (citation) - The arrangement of the copulatory organ is similar to copulatory organs found in the
family Mecynostomidae.  However, light microscopy of living specimens, confocal microscopy, and histological
sections reveal that the wall of the seminal vesicle is more muscular and orderly than that of any known
species in the Mecynostomidae.  The seminal vesicle of mecynostomids is typically a thin, unorganized network
of muscle fibers.  The family Dakuidae is further distinguished from the Mecynostomidae in having sperm with 9
+ 2 axonemes, instead of 9 + 1, and ventral body-wall musculature that has straight longitudinal muscles
between the frontal pore and mouth, and lacking sigmoid-shaped anterior diagonal muscles positioned between
outer circular and inner longitudinal muscles (Hooge 2001).  
It is likely that the Dakuidae is more closely related to other taxa that share similar sperm morphology and
patterns of body-wall musculature, such as the Actinoposthiidae, Haploposthiidae, Otocelididae, and some
species of the Convolutidae (see Hooge et al. 2002).

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