Dendrocoelidae Explained

Dendrocoelidae is a family of freshwater tricladida flatworms that has a holarctic distribution.

The largest freshwater triclad known belongs to this family, it's up to 40 cm in length and inhabits the Lake Baikal.^[1]

Description

The family Dendrocoelidae is characterized by an unusual arrangement of the muscle layers of the pharynx. While in most planarians the inner musculature of the pharynx is composed of two muscle layers, one circular and one longitudinal, in Dendrocoelidae the circular and longitudinal fibers are intermingled, forming a mixed layer.^[2]

Dendrocoelidae is the sister group of Kenkiidae. Both families have an anterior adhesive organ, which is considered a synapomorphy of the group.

Genera

The following genera are recognised in the family Dendrocoelidae:^[3]

• Genus Acromyadenium
• Genus Alaoplana
• Genus Amyadenium
• Genus Anocelis
• Genus Archicotylus
• Genus Armilla
• Genus Atria
• Genus Baikalobia
• Genus Baikalocotylus
• Genus Baikaloplana
• Genus Bdellocephala
• Genus Caspioplana
• Genus Dendrocoelopsis
• Genus Dendrocoelum
• Genus Hyperbulbina
• Genus Hyperpapillina
• Genus Microarchicotylus
• Genus Miodendrocoelum
• Genus Papilloplana
• Genus Polycladodes
• Genus Procotyla
• Genus Protocotylus
• Genus Rimacephalus
• Genus Sorocelis

Phylogeny

Phylogenetic supertree after Sluys et al., 2009:^[4]

Notes and References

1. Kozhov, M. 1963. Lake Baikal and Its Life. The Hague: W. Junk. vii + 344pp.
2. Sluys . R. . Kawakatsu . M. . 10.1111/j.1439-0469.2006.00371.x . Towards a phylogenetic classification of dendrocoelid freshwater planarians (Platyhelminthes): A morphological and eclectic approach . Journal of Zoological Systematics and Evolutionary Research . 44 . 4 . 274 . 2006 .
3. Web site: WoRMS - World Register of Marine Species - Dendrocoelidae Hallez, 1892. 2021-10-19. www.marinespecies.org.
4. Sluys . R. . Kawakatsu . M. . Riutort . M. . Baguñà . J. . A new higher classification of planarian flatworms (Platyhelminthes, Tricladida) . 10.1080/00222930902741669 . Journal of Natural History . 43 . 29–30 . 1763–1777. 2009 .