Convolutriloba macropyga

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Convolutriloba macropyga
Convolutriloba macropyga on an aquarium pane, underside, length 3.5 mm.  Above center, budding young animal.

Convolutriloba macropyga on an aquarium pane , underside, length 3.5 mm. Above center, budding young animal.

Trunk : Xenacoelomorpha
Sub-stem : Acoelomorpha
Class : Acoela
Family : Convolutidae
Genre : Convolutriloba
Type : Convolutriloba macropyga
Scientific name
Convolutriloba macropyga
Shannon & Achatz , 2007

Convolutriloba macropyga is a greenish, with up to 10 mm body length unusually large Acoel . The species is also found in reef aquariums and is considered a pest in the aquarium trade because of its strong reproduction. The additional species macropyga , from the Greek macro - large and pyga - abdomen, refers to the strong expansion of the rear region of the body, especially when turning towards the light ("sunbathing").


Convolutriloba macropyga is flat and shield-shaped. The body is rounded at the front end, notched at the rear. After widening, there is a constriction about 2 mm behind the front end, then the body widens again to the two lateral caudal lobes and the longer, slender, middle lobe. While immature specimens always have 3 caudal lobes, adult specimens can develop several medium-sized lobes, usually 2 to 3, in exceptional cases up to 9.

Convolutriloba macropyga are green, mottled with red by the symbiotic zoochlorella , scattered red secretory bodies (rhabdites) and a diamond-shaped, red spot of pigment cells in front of the caudal lobes. The dorsal body surface appears bluish in reflected light, caused by refractive deposits ( concretions ). Approximately 650 μm behind the front end of the body there is a pair of eye fields that appear colorless due to the absence of symbiotic algae.

Way of life

Like the other species in the genus, Convolutriloba macropyga reproduces asexually . The budding begins as a thickening at one point on the edge towards the rear end, on the side of the middle lobes up to and including the side lobes. The bud develops rotated by 180 ° to the longitudinal direction of the parent animal ("reverse budding") and does not detach from the parent animal, but is torn off when the bud attaches to the ground and pulls away. Up to 4 to 5 buds at different stages of development were observed on one dam. The species also reproduces sexually and releases relatively large eggs from which aposymbiotic (specimens that do not have symbiotic algae) hatch, which are equipped with a statocyst and a frontal organ (both of which are absent in adults).

Convolutriloba macropyga only has a narrow tolerance to temperature, salinity and light. It is tolerated between 18 and 28 ° C, with a salt content of 24 or 44 parts per thousand , the death rate is 50%. Convolutriloba macropyga does not survive complete darkness for more than 23 to 26 days, even if prey is present.

Research history

Only one of the species of the genus, Convolutriloba hastifera , has been described from its natural habitats. Convolutriloba macropyga was first collected in an aquarium in Marietta, Georgia ( United States ) and cultivated at the University of Georgia .

Individual evidence

  1. a b c d e Thomas Shannon, Johannes Achatz: Convolutriloba macropyga sp. nov., an uncommonly fecund acoel (Acoelomorpha) discovered in tropical aquaria. In: Zootaxa 1525, 2007, pp 1-17. ( Online )