Identification of Convolutriloba species


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A simple dichotomous key for the Convolutriloba species                        Download pdf

Convolutriloba species key

Convolutriloba macropyga buddingMembers of the Genus Convolutriloba are defined, literally, as bearing three posterior, caudal lobes or projections. All species are symbiotic with green algae and bear reddish-orange rhabdoid gland cells; the combination of these green algae and red gland cells gives the animals a reddish-brown appearance.

Given the similar morphology shared by different Convolutriloba species, accurate identification is best obtained during the asexual reproductive phase. As such, individuals should be isolated to allow for the observation of the released progeny.Convolutriloba longifissura fission

Two of the known species reproduce by reverse-budding whereby asexual progeny grow (bud) from the caudal edge and face in the opposite direction of the parent, i.e., 180° from the parent's anterior-posterior axis (see top figure at right). The other two species reproduce by transverse fission whereby the posterior quarter of the animal is shed (see bottom figure at right).

To identify your species, use the following key:


1. Asexual reproduction by reverse-budding: 2

1. Asexual reproduction by transverse fission: 3

      2. Distinct red spot visible forward of median caudal lobe – Convolutriloba macropyga

      2. Distinct red spot absent forward of median caudal lobe – Convolutriloba retrogemma

      3. Fission product undergoes longitudinal fission within 24 hours – Convolutriloba longifissura

      3. Fission product does not undergo further fission – Convolutriloba hastifera


Convolutriloba key


 Reference Literature

Åkesson, B., R. Gschwentner, J. Hendelberg, P. Ladurner, J. Muller, and R. Rieger. 2001. Fission in Convolutriloba longifissura: asexual reproduction in acoelous turbellarians revisited. Acta Zool. 82: 231-239.

Bartolomaeus, T., and I. Balzer. 1997. Convolutriloba longifissura, nov. spec. (Acoela) - first case of longitudinal fission in Plathelminthes. Microfauna Marina 11: 7-18.

Hendelberg, J., and B. Åkesson. 1988. Convolutriloba retrogemma gen. et sp.n., a turbellarian (Acoela, Platyhelminthes) with reversed polarity of reproductive buds. Fortschritte der Zoologie 36: 321-327.

Shannon, T., and J. G. Achatz. 2007. Convolutriloba macropyga sp.nov., an uncommonly fecund acoel (Acoelomorpha) discovered in tropical aquaria. Zootaxa: 1-17.

Winsor, L. 1990. Marine Turbellaria (Acoela) from North Queensland. Memoirs of the Queensland Museum 28: 785-800.