Current Herpetology
Online ISSN : 1881-1019
Print ISSN : 1345-5834
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Original articles
  • Hideo HASEGAWA, Yohei KADOTA, Yatsukaho IKEDA, Akiko SATO, Keiko MATSU ...
    Type: Articles
    2018 Volume 37 Issue 1 Pages 1-10
    Published: 2018
    Released: February 27, 2018
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    We evaluated helminth parasitism in the alien frog, Polypedates leucomystax, on Ishigakijima and Iriomotejima, Yaeyama Islands, Okinawa, Japan. Among 12 helminth species observed, the parasitic oligochaete, Allodero sp., may have been introduced by this frog to Ishigakijima without spreading to Iriomotejima. Raillietnema rhacophori, a nematode commonly parasitic in P. leucomystax of Okinawajima and Miyakojima, was not observed. Seven helminth species, namely, Mesocoelium sp., Rhabdias sp., Strongyloides sp., Cosmocerca japonica, Meteterakis sp., Oswaldocruzia hoepplii, Oswaldocruzia japalurae, Pseudoacanthocephalus sp. were surmised to be acquired from the endemic anurans and/or saurians in the Yaeyama Islands. This frog also serves as a paratenic host for Physalopteridae sp., Dispharynx sp. and Centrorhynchus sp./spp., in which adults are parasites of birds or snakes.

  • Soh KOBAYASHI, Seiya ABE, Motoshi TOMITA, Rikyu MATSUKI
    Type: Articles
    2018 Volume 37 Issue 1 Pages 11-22
    Published: 2018
    Released: February 27, 2018
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    Habitat fragmentation is one of the major threats to amphibian species. In a previous study, population genetic analyses of the Japanese brown frog Rana japonica were conducted using a mitochondrial DNA (mtDNA) marker in a typical Japanese agricultural landscape (known as satoyama) in Chiba, Japan. This previous study revealed that gene flow was restricted by the roads and cement-walled urban river that divide this site. In the present study, we reanalyzed the genetic structure of the same meta-population using microsatellite markers in comparison with the mtDNA results and elucidated fine-scale gene flow. The genetic structure derived from the microsatellite clustering analysis was almost identical to that of the mtDNA results, although some important details differed. We recognized boundaries of genetic structure are consistent with the major roads and cement-walled river, however, we also detected gene flow across those artificial barriers. We concluded that the current genetic structure was formed in the past when gene flow was strongly restricted. Gene flow among breeding populations is now being restored by the maintenance of breeding sites, although it is not sufficient to erase the signature of historical isolation.

  • Masafumi MATSUI, Noritomo KOMADA, Kumiko YAMADA, Makoto TAKADA, Kanto ...
    Type: Articles
    2018 Volume 37 Issue 1 Pages 23-29
    Published: 2018
    Released: February 27, 2018
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    The Japanese giant salamander, Andrias japonicus, is known to exhibit very low genetic diversity, but the number of individuals surveyed in a population is limited by now. We investigated partial sequences (673 bp) of mitochondrial cytochrome b gene in 180 specimens of a population from the Inuyama Head Works on the Kiso River, Central Japan, over nine years so as to clarify the degree of genetic diversity. The result again confirmed a tendency of lack of diversity; only one individual differed from the remaining 179 with an uncorrected p-distance of only 1.5%. The individual had the sequence identical with that reported for an individual from San’in District of Western Japan, far from the Kiso River, and is thought to have been introduced artificially. The healthy condition of the salamander population in spite of highly reduced genetic diversities might be due to possible decrease of inbreeding depression, resulting from the past purging effect of ancestral inbreeding wherein deleterious recessive alleles were eliminated from the gene pool.

  • Kihiro NOHA, Shohei TOYODA, Toshikazu TAKAI, Tomohiko SHIMADA
    Type: Articles
    2018 Volume 37 Issue 1 Pages 30-39
    Published: 2018
    Released: February 27, 2018
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    Although Fejervarya kawamurai is a common frog in the paddies of western Japan, their larvae seem to be scarce in the paddies where larvae of Hyla japonica and Pelophylax nigromaculatus are abundant. To examine the cause of this phenomenon, we surveyed the reproductive season of these three species at two sites with different irrigation schedules using an automatic recording system. In addition, we conducted several experiments to test three possible explanations; (1) maternal avoidance from P. nigromaculatus larvae in the selection of oviposition site, (2) predation on F. kawamurai eggs by P. nigromaculatus and the larvae of other species, and (3) negative interactions of P. nigromaculatus larvae on the larvae of F. kawamurai. In paddies flooded throughout the year, calling of H. japonica and P. nigromaculatus started far earlier than in F. kawamurai, whereas in paddies irrigated in mid-May, these three species started calling simultaneously. We found significant predation pressures on F. kawamurai eggs from larvae of H. japonica, Rana japonica, P. nigromaculatus, P. porosus brevipodus, Glandirana rugosa, F. kawamurai, and Rhacophorus schlegelii, whereas no significant predation pressures from larvae of B. japonicus was detected. We found no evidence of maternal choice by F. kawamurai for oviposition sites and no effects of P. nigromaculatus larvae on sympatric larvae of F. kawamurai. Our results suggest the possibility that the mortality rate of F. kawamurai eggs might increase through predation at paddies where H. japonica and P. nigromaculatus start oviposition earlier than does F. kawamurai.

  • Jeffrey E. LOVICH, Shellie R. PUFFER, Mickey AGHA, Joshua R. ENNEN, Ka ...
    Type: Articles
    2018 Volume 37 Issue 1 Pages 40-57
    Published: 2018
    Released: February 27, 2018
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    Agassiz’s desert tortoise (Gopherus agassizii) reaches the southern edge of its range in the Sonoran Desert of California. The reproductive ecology of this wide-ranging species is understudied here compared to populations in the adjacent Mojave Desert. Understanding potential geographic variation in reproductive ecology is important for effective management of conservation-reliant species like G. agassizii. We studied the fecundity and clutch phenology of female G. agassizii at two study sites in the Sonoran Desert region of Joshua Tree National Park over five years (1997–1999–2015–2016) spanning two of the strongest El Niño events on record and an epic drought. Across all years, mean clutch size was 4.3±1.5 eggs, mean clutch frequency was 1.78 clutches/female/year, and mean X-ray egg width was 36.51±1.56 mm, all of which are comparable to other published studies both in the Sonoran and Mojave deserts of California. Our results generally support earlier published findings that G. agassizii utilize a bet-hedging strategy of consistently producing small clutches almost every year, even during times of low annual primary productivity. A regionally warmer climate in the Sonoran Desert of California appears to have an effect on the timing of egg production, as the earliest dates of egg visibility in our study (April 6) were approximately two weeks earlier than the earliest dates reported for G. agassizii in the Mojave Desert. Shelled eggs were no longer visible in tortoises after mid-June in all years but the El Niño year 1998, when eggs were visible until mid-July.

  • Dai TOGANE, Kinji FUKUYAMA, Kotaro TAKAI, Noboru KURAMOTO
    Type: Articles
    2018 Volume 37 Issue 1 Pages 58-68
    Published: 2018
    Released: February 27, 2018
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    Body size and age of two populations of the endangered species Pelophylax porosus porosus from the Kanto Plain, Japan (paddy fields in valley bottoms [Zushi] and open plains [Hayamajima]) were investigated. Age was estimated by skeletochronology of the phalanges. Frogs grew rapidly between 0 and 1 year of age in both populations. The asymptotic snout-vent length (SVL) of both sexes peaked at 2 years. Age at sexual maturity was estimated to be 0–1 years for males, but 1–2 years for females. SVL in adults ranged from 45.2 to 67.2 mm in males, and 60.2 to 88.8 mm in females. In both populations, females were significantly larger than males. However, the SVL was not significantly different between the populations or between age classes in both sexes. Lines of arrested growth (LAGs) were observed in the periosteal tissue. Longevity was estimated to be 3 and 4 years in males and females, respectively. Pelophylax p. porosus is suggested to be the most short-lived and the first to reach sexual maturity compared with the other Pelophylax species in Japan, although the age structure differed between the populations. In both sexes, when comparing the age of 1 year old or older frogs, the Zushi population was significantly older than the Hayamajima population, but the longevity of the Hayamajima population was shorter than that of the Zushi population. As the two study sites differed in agricultural management, it is possible that the resulting environmental conditions influenced the longevity of P. p. porosus.

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