Mental salamanders

Fig. 3.2 Amphibian protein-chemosignalling PRF (plethodontid receptivity factor interleukin-6), broadcast from male salamander mental gland in the forward current produced by tail-fanning (after Arnold, 1997 Rollman, 1999).

Fig. 20.2 Pheromone delivery in Desmognathus ocoee salamanders and the method of pheromone delivery used during behavioural trials. A receptive female places her chin on the tail base of the male and typically straddles his tail. The male turns back towards the female and places his submandibular mental gland on her dorsum. The male then uses his premaxillary teeth to scratch the site on her dorsum that he has swabbed with his mental gland secretions. To mimic pheromone delivery in behavioural trials, each male was deglanded and a treatment solution was delivered to each female in a treatment patch (TrP) placed on her dorsum just posterior to the head. Photograph by Stevan J. Arnold...

Short-range transfer of chemical factors may require body contact. Male Appalachian woodland salamanders press or slap their mental gland on the nares of the female (Arnold, 1966). The pygmy salamander even pierces the skin of the female s head with his modified teeth and vaccinates it with the secretion from his mental gland. 

Courtship pheromones are not necessarily species specific. Pairs of the woodland salamander, Plethodon shermani, courted for an equally long time (about 35 to 50 minutes) whether male pheromone from the mental gland of conspecifics or the allopatric species P. montanus or P. yonahlosscc was present, even though the composition of the proteinacous pheromones (plethodontid receptivity factor of these three species differ considerably (Rollmann et al, 2003). 

Another salamander courtship pheromone, identified in 1999, is a protein. During courtship, males of the Appalachian woodland salamander, Plethodon jordani, (Plethodontidae), a terrestrial species, actively deliver a pheromone to the female. In the mating season, males develop a mental gland, located... 

Male courtship pheromones can increase the receptivity of the female. In the plethodontid salamander Desmognathus ochrophaeus the male courts the female hy scraping her dorsum with his specialized premaxillary teeth and swahs the same area with secretion from the mental gland on his chin, amounting to an injection. In an experiment, filter paper with an extract from the excised mental glands of males was placed on the dorsum of females. These treated females mated 28% (59 minutes) sooner than controls (Houck and Reagan, 1990). 

The terrestrial salamander Plethodonjordani applies courtship pheromone to the female hy ruhhing or slapping his mental gland directly on the female s nares. This way the pheromone can stimulate the vomeronasal organ and accessory olfactory system. Experimental application of mental gland extracts to the nares of females accelerated the time until active courtship started (Houck etal., 1998). 

In most plethodontid salamanders, courtship is terrestrial and the male does not clasp the female or restrain her in any way. The male, nevertheless, makes much physical contact with the female, crawling over and under her, or rubbing her snout with his head. In particular, the male frequently delivers secretions from specialized cephalic glands directly to the female. In Plethodon jordani, the male has an enlarged mental (submandibular) gland that he slaps over the female s nares (Arnold, 1977, Fig. 8). In a related species, yonahlossee, the male also slaps his mental gland over the female s snout (Arnold, 1972). Neither P. jordani nor P. yonahlossee males use their teeth to aid in secretion delivery. 

The only other experimental attempt to evaluate the effects of male courtship pheromones in salamanders is work conducted with the terrestrial plethodontid, Desmognathus ochrophaeus (Houck and Arnold, in prep.). Courtship interactions for this species (described above) involve pheromone delivery from the male s mental gland, and the probable use of premaxillary teeth to introduce this pheromone into the female s circulatory system. In their experiment, Houck and Arnold had three experimental male groups (1) Each male had its mental gland surgically removed, (2) Each... 

Sever, D. M., 1975, Morphological and seasonal variation of the mental hedonic glands of the dwarf salamander, Eurycea quadridigitata (Holbrook), Herpetologica, 31 241. 

Sever, D. M., 1976, Morphology of the mental hedonic gland clusters of plethodontid salamanders (Amphibia, Urodela, Plethodontidae),... 

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