AmphibiaWeb - Uperodon nagaoi
Uperodon nagaoi
Nagao's Globular Frog
family: Microhylidae
subfamily: Microhylinae
Species Description: Manamendra-Arachchi and Pethiyagoda. 2001. Journal of South Asian Natural History 5:122.

© 2010 Dr. Peter Janzen (1 of 5)
Conservation Status (definitions)
IUCN (Red List) Status Endangered (EN)
National Status None
Regional Status None
Access Conservation Needs Assessment Report.



View distribution map in BerkeleyMapper.

Uperodon nagaoi is a small-sized frog with snout vent length of 26.4 – 28.8 mm in males and 27.4 – 31.5 mm in females. Head wider than long (HL 76.6-88.6 % [83.3 %] of HW; HW 32.4-36.9 % [33.6 %] of SVL; HL 25.5-30.7 [28.0 %] of SVL). Nostril suboval, with a fleshy inner margin, dorsolaterally orientated, nearer to tip of snout than to eye (NS 48.0-66.7 % [50.0 %] of EN). Internarial slightly convex, internarial width greater than nostril-to-snout distance (IN 172.7-190.9 % [181.8 %] of NS). Canthal edges rounded. Snout truncate in dorsal aspect, rounded in lateral aspect (ES 35.9-15.3 % [45.3 %] of HL; ES 10.5- 12.7 % [12.7 %] of SVL) (see Fig. 3). Loreal region oblique, flat. Supratympanic ridge present. Tympanum not visible externally. Interorbital flat. Upper eyelid convex, fleshy, upper-eyelid width less than interorbital width (UEW 47.1-76.9 % [48.5 %] of 10). Lower eyelid transparent and membranous. Anterior end of mandible with a symphysial tubercle. Males with a gular vocal sac. A dermal ridge present a short distance behind each choana. Upper-arm length less than lower-arm length (UAL 83.6-107.7 % [87.0 %] of LAL; UAL 19.4-26.7 % [22.4 %] of SVL; LAL 23.0-25.7 % [25.7 %] of SVL). Palm length more than lower-arm length (PAL 105.8- 124.6 % [105.8 %] of LAL). Third finger longest, sometimes equal to second (FL III 52.1-70.3 % [58.0 %] of LAL). Relative length of fingers 1<2<4<3 (5 ex.) or 1<4<2=3 (1 ex.). Fingers free, a triangular dilation on their tips. Subarticular tubercles rounded or oval. Two palmar tubercles, convex, smooth: the inner one oval, smaller than the outer; the outer one subtriangular or rounded. Lateral dermal fringes present (Fig. 4). Femur length subequal to tibia length (FEL 91.9- 107.9 % [107.9 %) ofTBL; FEL 41.1-45.9 % [45.9 %] of SVL). Tibia length less than foot length (TBL 62.6- 68.0 % [62.6 %] of FOL; TBL 42.2-46.4 % [42.5 %] of SVL; foot length 62.5-69.4 % [67.9 %] of SVL). Fourth toe longest (TL IV 33.9-36.0 % [35.2 %] of FOL). Relative length of toes 1<2<5<3<4. Toe tips slightly truncate or rounded, enlarged, fleshy and smooth. Webbing on toes rudimentary (Fig. la-b). Two smooth metatarsal tubercles, the inner one oval, convex and larger than the outer, which is rounded and convex. Dorsum and sides somewhat rough; venter smooth. Tubercles present around vent, back and lower thigh (Manamendra-Arachchi and Pethiyagoda, 2001).

Colour in life: body both dorsally and ventrally is dark brown. Infraorbital, postorbital and upper lip with yellow spots. Reddish-orange patches present on snout, sides of dorsum, abdomen, around vent and on limbs. Distinct reddish orange cross-bars on proximal end of tibia and tibiotarsal articulation. Juveniles darker than adults (Manamendra-Arachchi and Pethiyagoda, 2001).

Colour in alcohol: body dark brown. Irregular dark brown patches on dorsum. Belly dark brown or ashy-dark brown with few light ashy patches. Some specimens have light brownish markings around the vent, tibiotarsal articulation and tarsi. Finger and toe tips, subarticular tubercles, palmar tubercles and metatarsal tubercles light ash (Manamendra-Arachchi and Pethiyagoda, 2001).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Sri Lanka


View distribution map in BerkeleyMapper.
Uperodon nagaoi is restricted to southern Sri Lanka (Manamendra-Arachchi and Pethiyagoda, 2001) and it is known from few other forests, specifically Sinharaja, Kithulgala, Athwelthota, Gilimale, Samanala, Kottawa-Kombala Forest near Hiyare, Nakiyadeniya, Dediyagala, Hiniduma, Beraliya- Elpitiya and low altitudes in Sri Pada Nature Reserve (Karunarathna and Amarasinghe, 2009; Garg et al., 2018; Wijayathilaka et al, 2018; Batuwita et al., 2019).

Life History, Abundance, Activity, and Special Behaviors
This species is found exclusively in tree-holes of several species of rainforest trees, including Myristica dactyloides (Myristicaceae), Syzygium makul (Myrtaceae) and a species of Diospyros (Ebenaceae) (Manamendra-Arachchi and Pethiyagoda, 2001; Karunarathna and Amarasinghe, 2009; Garg et al.,2018).

The species authority is: Manamendra-Arachchi K. and Pethiyagoda R. (2001).

Etymology: Uperodon nagaoi is named after Mr. Eijiro Nagao, President of Marusan Securities Co. Ltd. Of Japan, who is thanked for the Nagao Environmental Foundation's generous support of research into the amphibians of Sri Lanka (Manamendra-Arachchi and Pethiyagoda, 2001).

Uperodon nagaoi is found exclusively in tree-holes either alone or in mutualism relationship with at least two species of Poecilotheria sp. (Tarantula/ Tiger spiders) (Karunarathna and Amarasinghe, 2009).

Genetically, U. nagaoi is closely related to U. obscurus and U. palmatus; from these it was found to differ by an average uncorrected genetic distance of 5.6% (N = 6) and 4.0% (range 4.0–4.2%, N = 8), respectively (Garg et al.,2018; Wijayathilaka et al 2018).


Batuwita S, Udugampala S, DeSilva M, Diao J and Edirisinghe U. (2019). "A review of amphibian fauna of Sri Lanka: distribution, recent taxonomic changes and conservation." Journal of Animal Diversity, 1(2), 44-82. [link]

Garg S., Senevirathne G., Wijayathilaka N., Phuge S., Deuti K., Manamendra-arachchi K., Meegaskumbura M. and Biju S.D. (2018). "An integrative taxonomic review of the South Asian microhylidgenus Uperodon." Zootaxa, 4384(1), 1-88. [link]

Karunarathna D. M. S. S. and Amarasinghe A. A. T. (2009). "Mutualism in Ramanella nagaoi Manamendra-Arachchi & Pethiyagoda, 2001 (AMPHIBIA: MICROHYLIDAE) and Poecilotheria species (ARACNIDA: THEREPOSIDAE) from Sri Lanka." Tapbrobanica, 1(1), 16-18.

Manamendra-Arachchi K. and Pethiyagoda R. (2001). "Ramanella nagaoi, a new tree-hole frog (Microhylidae) from southern Sri Lanka." Journal of South Asian Natural History, 5(2), 121-133.

Wijayathilaka N, Senevirathne G., Bandara C., Rajapakse S., Pethiyagoda R., Meegaskumbura M. (2018). "Integrating bioacoustics, DNA barcoding and niche modeling for frog conservation -- the threatened balloon frogs of Sri Lanka." Global Ecology and Conservation, 16, 2351-9894. [link]

Originally submitted by: Dayupathi Eranda Nipunika Mandawala (2021-03-12)
Description by: Dayupathi Eranda Nipunika Mandawala (updated 2021-03-12)
Distribution by: Dayupathi Eranda Nipunika Mandawala (updated 2021-03-12)
Life history by: Dayupathi Eranda Nipunika Mandawala (updated 2021-03-12)
Comments by: Dayupathi Eranda Nipunika Mandawala (updated 2021-03-12)

Edited by: Michelle S. Koo (2021-03-12)

Species Account Citation: AmphibiaWeb 2021 Uperodon nagaoi: Nagao's Globular Frog <> University of California, Berkeley, CA, USA. Accessed Oct 19, 2021.

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Citation: AmphibiaWeb. 2021. <> University of California, Berkeley, CA, USA. Accessed 19 Oct 2021.

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