Mental Gland Research Articles

Observations on the Mental Hedonic Gland-Cluster of Eastern Salamanders of the Genus Plethodon

Mental glands of eastern salamanders of the genusPlethodon were examined to determine differences in shape, and to ascertain their value as a taxonomic character. Shape of the glands conforms to recognized species groups in smallPlethodon; all largePlethodon have generally the same shape regardless of species group.P. wehrlei appears intermediate, perhaps more closely allied with the largePlethodon. Mental gland shape of the cinereus species group appears similar to that of the westernPlethodon.

Morphological Variation and Ecology of the Salamander Phaeognathus hubrichti

A new locality for the species in Conecuh County, Alabama, is recorded. Specimens collected ranged from 31 to 120 mm snout to vent. Sexual maturity apparently occurs at about 100 mm body length in females, and near 80 mm in males. Mature males have no melanophores on the testis and no mental gland. Number of lobes of testes increases with increasing body length. The presence of a few large ovarian ova in 2 females suggests that there is probably no free-living, aquatic larva. Phaeognathus hubrichti seems able to start its own burrows only in loosely packed soil, but can enlarge and use previously formed cavities and tunnels. Gut contents of P. hubrichti and Plethodon glutinosus are similar, and differ from those of Desmognathus monticola. P. hubrichti feeds at the burrow entrance on surface-dwelling food. All specimens of P. hubrichti examined were infested with intestinal flukes and colic roundworms.

Some Aspects of the Life History and Ecology of the Salamander Leurognathus

Leurognathus inhabits trout streams in the southern Appalachian Mountains from southwestern Virginia to northeastern Georgia. These salamanders have a discontinuous distribution; they are strangely absent from some drainages. Specimens are best collected by diverting the flow of water so that a part of the stream bed is drained. This area is then carefully searched and the routed animals captured with the use of a funnel-shaped trap made of screen or fine-mesh hardware cloth. Some individuals attain a maximum snout-vent length of 78 mm and a weight of 13 grams. Generally males are larger than females, have a relatively wider head, less vomerine teeth, enlarged maxillary teeth, a larger and papillated cloaca, and an enlarged (but not conspictious) mental gland. Spawning occurs chiefly in June. Eggs are attached to the underside of a rock located in the main current. They average about 40 per clutch and hatch in about three months. Hatchlings average 11 mm in snoutvent length. The larval stage may be as short as 10 months or as long as 20 months. The average size at metamorphosis varies seasonally and geographically. It ranges from 25 to 38 mm; the over-all average is near 30 mm. Males reach sexual maturity when about 50 mm in snout-vent length and at least two years of age. Females mature when they are three years old and about 55 mm in size. Maximum size is probably approached at the age of five years. There is no evidence that either sex prefers a special habitat or that the sex ratio is other than one to one. Leurognathus are mainly noctural and secretive. They spend much time under rocks and feed almost exclusively on the larval or nymphal forms of aquatic insects. Much geographic and individual variation in body proportions and in coloration and markings occurs in this species. One of the most interesting types of variation involves the absence of dark pigment. These specimens are mostly whitish-yellow but may have dark blotches over both venter and dorsum. Some completely lack dark markings, but all have normal colored eyes and soles of the feet. The incidence of albinistic specimens has gradually increased from less than one per cent in 1954 to nine per cent in 1960. No albinistic larvae have been found. The smallest specimen showing such albinism measured 39 mm from snout to vent. However, some specimens as small as 45 mm were among the most albinistic ones collected. Thus a very conspicuous change in phenotype may occur in individuals and in populations within a relatively short period of time. A survey of the morphological features and adaptive trends of desmognathine salamanders supports retention of the genus Leurognathus. This content downloaded from 207.46.13.86 on Sun, 16 Oct 2016 04:35:27 UTC All use subject to http://about.jstor.org/terms 2 THE AMERICAN MIDLAND NATURALIST 67(1)

Courtship and Spermatophore of Plethodon jordani metcalfi

In general, the courtship of P. j. metcalfi follows the pattern described by Noble and Brady (1930) for plethodontid salamanders. Furthermore, the pattern observed in the field was found to correspond rather closely to that displayed by captive specimens. A generalized courtship pattern for P. j. metcalfi appears in Figures 1 and 2. These figures represent the more usual positions assumed during courtship and were drawn from numerous field sketches. The figures do not, however, include the many variations as observed in the details of courtship. The male usually approaches the female and executes a series of nosing movements using his snout and nasolabial grooves. The male then places his mental gland and nasolabial grooves in contact with the side, back, or more often the tail of the female and executes a foot dance in which the limbs are

Seasonal Variation in the Mental Gland and Reproductive Organs of the Male Eurycea bislineata

T HE males of several genera of plethodontid salamanders possess a glandular patch on the chin. Dunn (1926) describes this mental gland only in Desmognathus but Noble (1927), who has assigned a hedonic function to the structure, mentions it as being best developed in Oedipus, Hydromantes and Eurycea. Noble (1929) states that among other secondary sex characters, the presence of the mental gland may be used to distinguish male from female Eurycea from October to May and possibly longer. The secretions of this hedonic gland, together with those from smaller glandular areas on the eyelids, jaws, neck and temporal region, apparently serve to attract and excite the female during courtship when the snouts of the two sexes are rubbed against each other. The material presented in this paper concerns observations on the cyclic changes in the mental gland and reproductive organs of the male plethodontid salamander, Eurycea bislineata bislineata (Green), preliminary to some experimental studies on its endocrine system.