Description
Odorrana splendida is a frog with two distinct morphotypes: common and large. Females of the common morphotype have a snout-vent length that ranges from 94.6 - 110.5 mm while females of the large morphotype range from 112.1 - 137.4 mm. Males of the common morphotype range from 74.4 - 109.3 mm while males of the large morphotype range from 111.1 - 124.4 mm. Despite differences in body size, body proportions between these two morphotypes are similar to one another. As a whole, the species is large and rather flat. The head width is generally greater than the head length and comes to an end with a blunt snout. The canthus rostralis is also blunt and the loreal region is heavily concave, as is the top side of the upper jaw. The nostrils are located closer to the end of the snout than to the eyes, which are 1.8 times the diameter of the tympanum. The inter-orbital distance is smaller than the space between the nostril and shorter than the upper eyelids. The entire dorsal surface, including the upper side of the limbs, is covered by rough tubercles of varying sizes. This contrasts the smooth ventral surface of the species. The fore- and hind limbs of the body are stout. The large hands have well-developed disks and palmar tubercles. The thenar tubercle is large. The connection between the disc and penultimate phalanx region is sharply bent downward. Finger length increases as follows: F3 > F1 > F2 > F4, with webbing absent between fingers and well-developed subarticular tubercles. The shank is longer in length than is the thigh, which is longer than the foot. The inner metatarsal tubercles are well-developed. Toe length increases as follows: T4 > T5 > T3 > T2 > T1, with large discs and large webbing. The webbing reaches the base of the disk for all toes with the exception of T4, where the webbing reaches the ultimate subarticular tubercle. The subarticular are well-developed (Kuramoto et al. 2011).

Tadpoles reach a maximum snout-vent length of 18.5mm (Iwai et al. 2019).

DIAGNOSIS:

COLORATION:

Coloration is similar between the two morphotypes and sexes of O. splendida. In life, the dorsal ground is described as light yellow to green in color. The tubercles on the dorsal surface are encircled by blotchy spots of dark purple and golden-brown. These spots are contained within a rugged, purplish-black border. The very tips of the tubercles are yellowish-green. Thin, short gold lines extend from the center of these tubercles. The margins of the spots are frequently covered in smaller tubercles with light tips. The upper surface of the thigh retains four or five discontinuous crossbars that detach into small, irregular spotting. The entire ventral surface of the species is milky white with medium-sized gray blotching on the throat and upper chest, as well as faint blotching on the abdomen. A few blackish spots may be observable on the underside of the shank. Preserved in alcohol, however, the specimen is grayish in color, with the tips of the dorsal tubercles appearing light brown. The tympanum is brown with small gray spots near the center. The irregular crossbars on the hind and forelimbs are dark gray, and the lateral sides are reticulated. Webbing in between the toes has dark mottling. The ventrum is white, with the exception of black spots on the brim of the lower jaw and muted gray spotting on the throat and chest (Kuramoto et al. 2011).

Variation

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map in BerkeleyMapper.

Odorrana splendida is endemic to the Amami Islands, an archipelago in the Ryukyu islands of southwest Japan that belongs to the Kagoshima Prefecture. The island has a humid, subtropical climate with year-round precipitation. The species inhabits montane stream regions of the island surrounded by forest (Igawa et al. 2013). Notably, the distributions of the large and common morphotypes do not overlap. The large morphotype is found exclusively on Uken-son, a mountainous village that occupies the southernmost portion of the west coast of Amami-Ōshima (Kuramoto et al. 2011). The species ranges in elevation from 0 to 694 meters (IUCN 2015).

Life History, Abundance, Activity, and Special Behaviors
Odorrana splendida is one of the larger, ground-dwelling native species on the Amami Islands (Watari et al. 2008)

This species breeds in headstreams in areas with less water flow and abundant rock holes. It continues to breed through larval development, with a breeding season from late January to May peaking in February and March (Ministry of the Environment 2014).

Male calls can be heard from April to June (Kuramoto et al. 2011). The males call while perching on trees or on rocks by breeding holes (Utsunomiya and Utsunomiya 1983). The calls are prominent and loud, occurring almost all night long. During the peak breeding season, calls can be heard during the daytime. In a study regarding calling-site preferences of endemic frog species on Amami-Oshima Island, researchers observed the maximum number of calls counted every three minutes to be from 23 to154 calls at 12 different streams (Iwai et al. 2018).

Odorrana splendida is oviparous and undergoes indirect development. The species lays eggs in rock crevices or under the ground of rocky headstreams in flowing water. After the tadpoles hatch, they spend a rather long larval period in the stream that may exceed 2 years and disperse up to 90 m per year from the breeding site. They undergo metamorphosis from late June to early September (Iwai et al. 2019).

Odorrana splendida often preys on ground dwelling invertebrates, with invertebrates of the Rhaphidophoridae family known to be important to local frog species, including O. splendida (Iwai et al. 2016).

The small Indian mongoose (Herpestes javanicus) was introduced to the O. splendida’s habitat in order to control a population of poisonous pit vipers. This generalist species of mongoose ended up causing major declines in several populations of native species, including O. splendida (Watari et al. 2008). The Japan Ministry of the Environment began an eradication project for the mongoose problem in 2000, and O. splendida has since been in the process of recovering (Watari et al. 2013).

Trends and Threats
The population size of the species is currently decreasing, with a continuing decline of mature individuals (IUCN 2015). However, the exact population size is unknown. Threats to O. splendida include forest fragmentation, roadkill, and the biggest threat, the Indian mongoose invasion (Yamada and Sugimura 2004). Forest fragmentation, due to road construction and logging, is thought to be linked to reductions in habitat and breeding grounds (IUCN 2015; Ministry of Environment 2014).

Odorrana splendida (previously classified as O. ishikawae) is one of the larger, ground-dwelling native species in the area, thus making it more vulnerable to the mongoose because these generalist predators tend to select larger, more profitable prey (Watari et al. 2008). Watari et al. (2013) reported that the population began to recover after the eradication of one of the Indian mongoose, but its habitat and breeding grounds have not recovered.

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Habitat fragmentation
Predators (natural or introduced)
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

PHYLOGENETIC RELATIONSHIPS:

Maximum Likelihood and Maximum Parsimony analyses on 16S mtDNA, along with morphometric analysis indicate that O. splendida is a unique species and sister to O. ishikawae (Kuramoto et al. 2011).

It is suggested that the ancestral populations of O. ishikawae were separated into two lineages during the lower Pleistocene after the single landmass of Amami-Okinawa split into two separate islands—Amami Island and Okinawa Island. This geographic split is thought to have caused the speciation of two other sister groups, O. amamiensis with O. narina and B. subaspera with B. holsti (Kuramoto et al. 2011).

ETYMOLOGY:

The specific epithet, “splendida”, comes from the Latin word “splendidus” meaning “bright” or “brilliant”, referring to the species’ beautiful coloration (Kuramoto et al. 2011).

OTHER INTERESTING INFORMATION:

Odorrana splendida is occasionally referred to as the most beautiful frog in Japan (Kuramoto et al. 2011).

References

IUCN SSC Amphibian Specialist Group (2015). "Odorrana splendida." The IUCN Red List of Threatened Species 2015: e.T54314436A54316058. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T54314436A54316058.en. Downloaded on 17 February 2021.

Igawa, T., Oumi, S., Katsuren, S., Sumida, M. (2013). “Population structure and landscape genetics of two endangered frog species of genus Odorrana: different scenarios on two islands.” Heredity, 110, 46-56. [link]

Iwai N., Yasumiba K., Takahara T. (2019). “Efficacy of environmental DNA to detect and quantify stream tadpoles of Odorrana splendida.” R. Soc. open sci. 6: 181798. [link]

Iwai, N., Watari, Y., Ishii, H., Akasaka, M. (2016). “Are forest roads attractive hunting sites for frogs? A comparison of on-road and in-forest prey biomass and composition in Amami Island.” Current Herpetology 35(1):1-7. [link]

Iwai, N., Yasumiba, K., Akasaka, M. (2018). "Calling-site preference of three co-occurring endangered frog species on Amami-Oshima Island." Herpetologica 74(3):199-206. [link]

Kuramoto, M., Satou, N., Oumi, S., Kurabayashi, A., Sumida, M. (2011). “Inter-and intra-island divergence in Odorrana ishikawae (Anura Ranidae) of the Ryukyu Archipelago of Japan, with the description of a new species.” Zootaxa, 2767(1), 25-40. [link]

Ministry of the Environment, Government of Japan (2014). Threatened Wildlife of Japan - Red Data Book 3rd ed. Reptilia/Amphibia. GYOSEI Corporation, Tokyo.

Utsunomiya, Y., Utsunomiya, T. (1983). “On the eggs and larvae of frog species occurring in the Ryukyu Archipelago.” Journal of Faculty of Applied Biological Science, Hiroshima University, 22, 255–270.

Watari, Y., Nishijima S., Fukasawa, M., Yamada, F., Abe, S. and Miyashita, T. (2013). “Evaluating the 'recovery level' of endangered species without prior information before alien invasion”. Ecology and Evolution 3(14): 4711-4721 [link]

Watari, Y., Takatsuki, S., Miyashita, T. (2008). “Effects of exotic mongoose (Herpestes javanicus) on the native fauna of Amami-Oshima Island, southern Japan, estimated by distribution patterns along the historical gradient of mongoose invasion”. Biological Invasions 10: 7. [link]

Yamada, F., Sugimura, K. (2004). “Negative impact of an invasive small Indian mongoose Herpestes javanicus on native wildlife species and evaluation of a control project in Amami-Ohshima and Okinawa Islands, Japan”. Global Environmental Research, 8(2), 117-124.

Species Account Citation: AmphibiaWeb 2022 Odorrana splendida: Amami Oshima Frog <https://amphibiaweb.org/species/7629> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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