A new aestivation strategy for land molluscs: hanging upside down like bats

Introduction: Many land molluscs survival strategies are still poorly understood or have not been even reported, especially in the Neotropics. Methods: I collected 25 adult Tikoconus (Tikoconus) costarricanus from Reserva Forestal Río Macho, Costa Rica. I kept the specimens for 8 days in terrariums to film their behavior. Objective: To analyse the behavior of T. costarricanus, with emphasis on its strategies to survive drought and probably also predation. Results: This snail has at least three unusual behaviors that probably help them reduce dehydration and may be escape from enemies and avoid diseases: hanging upside down like bats, falling and grooming. During aestivation, they compress the body and hang upside down from leaves, like bats hang from perches. They attach to the underside of leaves with mucus from a caudal gland. Disengagement is done with vigorous shell rotations and foot twisting in contorting sequences, and can be done as reaction to direct sunlight, and probably to avoid predators and parasites. They groom their own shell, shell lappets and foot, an unusual behavior among land snails. This species feeds mainly on epiphyllous mosses, algae and lichens, occasionally adding arthropod eggs and carrion. Egg laying is similar to other euconulids and valloniid snails. Conclusions: Aestivating hanging upside down is a drought avoiding trait described here for the first time and is also a new function for the caudal gland mucus. Leaf detaching is done by a contortion sequence of shell rotations and foot twisting; its complexity and duration varies according to the leaf side where the snail is located.

Two new species of the genus Daptonema Cobb, 1920 (Nematoda: Xyalidae) found in an intertidal seagrass bed on the coast of the Andaman Sea, Thailand, with reference to the taxonomic status of the genus Trichotheristus Wieser, 1956

Daptonema chonispiculum sp. n. and D. phuketense sp. n. are described from the Ban Pa Khlok seagrass bed, Phuket Province, Thailand. Daptonema chonispiculum sp. n. is characterized by spicules with funnel-shaped proximal ends, and D. phuketense sp. n. is unique in having the third caudal gland filled with fibrous contents. Each new species also differs from most related species in body length, de Man’s indices, length of the cephalic setae and somatic/cervical setae, distance of the amphids from the anterior of the body, and length of the spicules. The new species most closely resemble D. hirsutum, D. platonovae, and D. robustum, with similar body lengths, long cervical setae located in the anterior pharyngeal region, small amphids, L-shaped spicules and a gubernaculum with a long dorso-caudal apophysis. Regarding the taxonomic status of Daptonema and Trichotheristus, we agree with the synonymization of Trichotheristus with Daptonema by Tchesunov (1990), based on taxonomic review of Trichotheristus and a comparison of the diagnostic features separating the genera. We propose a new combination, Daptonema galeatum comb. n., and a new name, Daptonema nearticulatum sp. n. for Trichotheristus articulatus Huang & Zhang, 2006.

Expression of prolactin receptor (PRL-R) mRNA in the caudal gland of Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884)

We applied the in situ hybridization technique to the Hokkaido sika deer (Cervus nippon yesoensis) caudal glands using probes designed from the red deer (Cervus elaphus) prolactin receptor cDNA. Prolactin receptor mRNA expression was consistently detected in the secretory epithelial cells collected from fawns and lactating hinds. This suggests that the presence of developed caudal glands during late pregnancy and lactation may be caused by increased blood levels of prolactin. During late pregnancy and lacation, visual range is limited for deer in forests and grasslands because of the flourishing leaves and sprigs. Therefore, we suggest that the scent emitted from the caudal gland in a particular season coordinates with and reinforces the visual alarm effect of the rump patch and tail.

Cercaria vaullegeardi Pelseneer, 1906 (Digenea: Hemiuridae); development and ultrastructure

SUMMARYCercaria vaullegeardi develops in daughter sporocysts within the digestive gland of the prosobranch Gibbula umbilicalis. On emergence into the host mantle cavity the cercarial body retracts into the cystophorous tail, the ‘encysted’ cercaria being then shed into the sea. The encysted cercaria is described at the ultrastructural level for the first time and developmental stages are redescribed. The cercarial body has no penetration or cystogenous glands: a single type of sub-tegumental secretory cell produces vesicles containing neutral mucopolysaccharides which pass into the tegument at encystment. The immotile cystophorous tail consists essentially of a fibrous caudal cyst and 8 appendages including a delivery tube. Scanning electron micrographs show the surface of tegumental membranes enveloping the caudal cyst to be covered with a honeycomb pattern of indentations derived from electron-lucent vesicles produced by the caudal gland. The fibrous-walled delivery tube comprises proximal and distal sections and a modified terminal end-piece.

Structural and functional aspects of tail squirting: a unique defense mechanism of Diplodactylus (Reptilia: Gekkonidae)

The structure of a unique caudal gland is described for the first time. Glandular material is secreted and stored in a series of caudal chambers that makes up the bulk of the tail. The glandular secretion is forcibly ejected from each chamber through a middorsal rupture zone in the epidermis. Localized contraction of caudal musculature causes ejection of the defensive secretion.All species of Diplodactylus that were known or suspected to be tail squirters plus representatives from each of four other species groups were examined. The following species of Diplodactylus have caudal glands: D. ciliaris, D. elderi, D. michaelseni, D. spinigerus, D. strophurus, D. taenicauda, and D. williamsi.Regenerated tails of gland-bearing species contain a regenerated caudal gland which is structurally different from the original. Here all evidence of segmentation is lost and there is no series of epidermal rupture zones. A pair of elongated secretion masses is found within paired, elongated caudal chambers.The results of a preliminary bioassay indicated that caudal gland secretion may be unpalatable to potential predators and thereby protects the species of Diplodactylus that are tail squirters. The very sticky nature of the secretion may complement the repellant effects of the odorous constituents.