Convolutriloba macropyga sp . nov . , an uncommonly fecund acoel ( Acoelomorpha ) discovered in tropical aquaria

A new species of Convolutriloba Hendelberg & Åkesson, 1988, collected from an aquarium in Marietta, Georgia, USA, and cultured at the University of Georgia comprises exceptionally large individuals, up to 10 mm in length. Like other members of the genus, Convolutriloba macropyga sp. nov. reproduces asexually and possesses symbiotic zoochlorellae, but it also routinely reproduces sexually, laying relatively large eggs that hatch into aposymbiotic juveniles with a statocyst and frontal organ (which are absent in the adults). C. macropyga has a narrow tolerance for extremes of temperature and salinity: it cannot survive outside of a temperature range of 18–28°C and suffers 50% lethality at salinity as low as 24 ppt and as high as 44 ppt. It cannot survive total darkness for longer than 23–26 days, even with prey provided, suggesting an obligate symbiosis with its algal endosymbiont. A method for inducing sexual reproduction in other convolutrilobids is presented, as are suggestions for successful shipping of these acoels.