Turbellarian taxonomic database

Macrostomorpha Dolichomicrostomida Notes

Original text from Janssen et al (2015), p. 87 (citation): 
"Our results strongly support a monophyletic grouping of the
Microstomidae and the Dolichomacrostomidae—a clade we propose
to name Dolichomicrostomida—and they do not support the
traditional placement of the Microstomidae at the base of the
Macrostomorpha. The presence of asexual fissioning was thought
to be a basal trait, linking the Microstomidae with the
Catenulida, a hypothesis clearly rejected by our ASR (see
Section 3.3.1). Tyler (1976), in a comparative study of adhesive
gland morphology, concluded, with cautious reservation, that the
Microstomidae may be closer to the Macrostomidae, with which
they share insunk anchor cells and long papillae, than to the
Dolichomacrostomidae, which have a similar branching pattern
of the releasing gland neck. He also suggested that the association
between rhabdites and adhesive papillae indicated a closer association
of Dolichomacrostomidae to Bradynectes than to the
Microstomidae. Both hypotheses are rejected by our results.
Indeed, Rieger (2001) argued that the insunk anchor cells could
have evolved convergently, as the anchor cells in the
Microstomidae are not insunk as deeply as those in
Macrostomum, and that the association between rhabdite glands
and adhesive papillae is debatable, suggesting a closer relationship
between the adhesive glands of the Microstomidae and
Dolichomacrostomidae. Likewise, Riedel (1932) grouped
Microstomidae and Dolichomacrostomidae, based on similarities
in the process of oogenesis. Finally, two rDNA based molecular
phylogenies (Littlewood et al., 1999; Litvaitis and Rohde, 1999)
also recovered this grouping, albeit with low taxonomic coverage
of the Macrostomorpha. Despite the strong molecular evidence
for the Dolichomicrostomida there are currently no morphological
apomorphies to diagnose this clade."

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