Larval anuran jaw sheaths are corneous flat covers overlying the lateral surface of upper and lower jaws. Although most anuran tadpoles have a single sheath on both jaws, some have a pair of divided sheaths on one or both jaws, and sometimes both undivided and divided conditions are observed even within a species. We examined morphology of larval specimens tentatively identified as Meristogenys amoropalamus, collected from Borneo, and found that the lower jaw sheaths changed from a divided to an undivided state with larval development. Furthermore, the numbers of undivided rows of lower labial tooth, and of serrations of upper and lower jaw sheaths also changed ontogenetically. From these observations, we suggest that developmental stages should be taken into consideration when we use these larval characters for morphological comparisons in this genus.
The populations of a frog long identified as Fejervarya limnocharis from the Southern Ryukyus (=Sakishima in conventional regional name), Japan, considerably differ genetically and morphologically from the topotypic population of the species from Java. These Southern Ryukyu populations are therefore judged to represent a distinct biological species, which is described here as Fejervarya sakishimensis. This new species differs from F. limnocharis in larger snout-vent length (SVL). Also, it is distinguished from the latter in shorter head and tibia, smaller eye and narrower internarial space, all relative to SVL, and larger ratio of the first toe length to the inner metatarsal tubercle. From F. multistriata, F. sakishimensis differs by relatively larger tympanum, wider head, upper eyelid and anterior and posterior spaces of eyes, and longer forelimb and first toe, besides larger SVL. Furthermore, F. sakishimensis has a larger body, and relatively shorter head, tibia and hindlimb than F. iskandari. Also, this species is differentiated from all other nominate taxa of the F. limnocharis complex by a combination of some morphological characteristics.
We compared six taxa of the genus Fejervarya from central Western Ghats, southwestern India, including F. rufescens, F. sahyadris, and four taxa that possess distinct mtDNA haplotypes as demonstrated by our previous studies. Morphological comparisons with F. brevipalmata, F. keralensis, F. nilagirica, and F. syhadrensis on the basis of literature descriptions and museum specimens revealed that the four haplotypes do not correspond to any of the previously described species. Therefore, they are named herein as new species. Although each of these new species was separated clearly by discriminant analyses, two large-bodied species, as well as two small-bodied species, occurring sympatrically or parapatrically in many collecting sites, were very similar to each other in external appearance. Acoustic characteristics available for five of the six species were most conspicuous and diagnostic features. This study revealed the occurrence of active speciation in Fejervarya in the Western Ghats, one of the hot spots of biodiversity in the world.
To reconsider a classic theory that prolactin induces water-drive behavior in migratory salamanders (i.e., prolactin-based water-drive theory), I showed, with a brief review of past references, some disprovable data on the basis of “migratory activity type” and “mucus secretion” in the hynobiid salamanders, Hynobius hidamontanus and Salamandrella keyserlingii. This theory could not explain fall immigrations toward terrestrial hibernacula unrelated to mating in S. keyserlingii. Likewise, literature review indicated that it also could not explain breeding immigrations toward dry pond basins in Ambystoma opacum and toward terrestrial nest-sites adjacent to the water in Tylototriton (Echinotriton) andersoni. Mucus that was secreted from dermal mucous glands, a target organ for prolactin, was absent on the skin of both fall-nonbreeding and spring-breeding immigrants of S. keyserlingii. In the context of existence of ecological and physiological examples against the prolactin-based water-drive theory, which have been so far neglected in endocrinological studies, it is conclusively necessary to determine plasma prolactin concentrations in salamanders just before entering the water.
A common view of biologists for animal coloration is that this characteristic has various ecophysiological functions. Snakes exhibit a variety of colorations in their simple elongated body. Stimulated by their diversified color morphs, various types of studies attempting to elucidate functions of snake colorations have been conducted. Although a few exceptions exist, most of these studies classified color morphs into discrete categories. However, when we treat species having heterogenous color patterns in a single individual and species exhibiting continuous individual variations of coloration, it is often difficult to categorize samples into discrete morphs based on its coloration because we must ignore some characteristics and continuous variations of coloration. Principal components analysis (PCA) is an appropriate method to treat such species because each coloration can be represented by a numerical value as an independent point within a continuum of color variants. However, we cannot know, a priori, how many and what kinds of variables are at least necessary to adequately represent features of the whole sample. The aim of this study is, by adopting variable selection in PCA, to identify and provide a “least set of variables”, which is the least number of characteristics of color pattern necessary to measure when we evaluate and rank individual snakes based on their coloration. Using Elaphe quadrivirgata as a model subject, we found that 10 variables can represent features of the whole sample of the subject to the same degree as 53 original variables. Possible applications of this proposed method to behavioral studies are discussed.
Fig. 5. Plastra in dorsal views of Geoemyda amamiensis and the two extant congeneric species. A, G. amamiensis (RUMF-GF-5011, holotype). B, G. spengleri (KUZ R62351). C, G. japonica (KUZR R62453). Abbreviations are: EPI, epiplastron; ENT, entoplastron; HYO, hyoplastron. Scale bars equal 10 mm.
Wrong:B, G. japonica (KUZR R62453). C, G. spengleri (KUZ R62351).
Right:B, G. spengleri (KUZ R62351). C, G. japonica (KUZR R62453).