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Hermaphroditic animals display a remarkable range of complex mating behaviours that are frequently related to the transfer of accessory-gland products. Here, we describe the use of the dart, an accessory reproductive device, and the mating behaviour of the hermaphroditic Cuban tree snail Polymita picta. Mating can be divided into three stages: courtship, copulation and post-copulation. Polymita picta has the longest mating duration of all Polymita species investigated so far. During courtship, a partial genital eversion exposes the sensitive zone, genital lobes and dart apparatus. During all mating stages, three uses of the dart apparatus can be distinguished: wiping, rubbing and stabbing, all of which mainly target the anterior region of the body, usually without loss of the dart. Morphological variation in the dart involves the extent of curvature, irregularities along the length and total length. These characteristics possibly provide a larger contact surface and deeper penetration through the body wall, which could result in increased sperm storage and paternity. The spermatophore is equipped with spines and we suggest that these might slow down spermatophore uptake into the bursa copulatrix. Overall, the general mating pattern, the presence of the sensitive zone, repeated use of the dart and its shape diversity support the idea that in more ancestral dart-possessing snails the dart apparatus is used to transfer accessory gland secretions, not only by stabbing but also through wiping and rubbing. [ABSTRACT FROM AUTHOR]

Many species of pulmonate land snails are equipped with one or more so-called "love darts". Even though the number and shape of these calcareous darts vary considerably between species, dart use has only been investigated in very few species. Here, we redescribe the mating behaviour of Polymita muscarum because previous reports did not include the use of the dart apparatus. Mating in this hermaphroditic land snail can be divided into three stages: courtship, copulation and post-copulatory activity. During courtship, full eversion of the genital atrium is reached, thus exposing the sensitive zone, genital lobes and dart apparatus. We observed that P. muscarum pushes the everted dart apparatus repeatedly onto different parts of the partner's body and does not lose its dart after stabbing. Dissected specimens had a single, slender dart with a round base, a broad corona and a circular cross-section. We propose that the morphology of P. muscarum 's dart is consistent with the idea of simple darts needing to be stabbed more often in order to increase the transfer of mucus, which contains a biologically active substance (i.e. allohormone) that enhances the chances of paternity. Besides adding to the growing diversity in the use of love darts in land snails, these findings contribute to the understanding of the evolution of this peculiar reproductive act. [ABSTRACT FROM AUTHOR]