The Alycaeidae are characterized by a complex gas exchange device, which consists of a sutural tube that is closed at its end, and several, perpendicularly running, narrow microtunnels. A single report, published in a hard-to-access journal, mentioned that the tube is formed “backwards”, but the author provided no illustrations. Here I publish photos and SEM micrographs of an adult alycaeid shell with an incompletely developed tube, and a subadult alycaeid shell with microtunnels, but no sutural tube. Both cases suggest that the sutural tube is indeed formed “backwards”, after all microtunnels are completed. With this, the previous observation is confirmed. |
