Theloderma horridum ( Boulenger, 1903 )

Figueroa, Alex, Low, Martyn E. Y. & Lim, Kelvin K. P., 2023, Singapore’s herpetofauna: updated and annotated checklist, history, conservation, and distribution, Zootaxa 5287 (1), pp. 1-378 : 62-63

Theloderma horridum ( Boulenger, 1903) — Native.

Ixalus horridus Boulenger, 1903: 139–141 , pl. 6, fig. 2. Syntypes (12): original number unknown, but includes BMNH 1903.4.13.111–112 and 1903.4.13.113–122, according to Bossuyt & Dubois (2001: 37). Type locality: “ Patani States … near our camp on Bukit Besar”, Pattani, Thailand.

Thorny Bush Frog

( Figure 7F )

Singapore records.

Theloderma horridum — Leong et al., 1996: 475–477 (Taban Valley [ BTNR]).—R.C.H. Teo & Rajathurai, 1997: 400 (Taban Valley [ BTNR]).—T.M. Leong & L.M. Chou, 1999: 117–118.—T.M. Leong, 2000: 8.—K.P. Lim & F.L.K. Lim, 2002: 145.—K.K.P. Lim & T.M. Leong, 2008: 159, 264.—N. Baker & K.P. Lim, 2008: 61, 159 (Bukit Timah Nature Reserve).—T.M. Leong & S.C. Teo, 2009: 24.—Bickford et al., 2010: 123.— Davison, 2011: 109.—L.L. Grismer, 2011a: 64.—Figueroa & Selveindran, 2011: 259–261 (Nee Soon Swamp Forest).—P.K.L. Ng et al., 2011: 487.—T.M. Leong, 2011: 20, 22.—N. Baker & K.P. Lim, 2012: 61, 159.—K.Y. Chong et al., 2013: 289.—W. Wong, 2017: 53.—R.C.H. Teo & Thomas, 2019: 153, 179.

Remarks. After Leptomantis cyanopunctatus , T. horridum is Singapore’s second rarest frog. After being first discovered in Singapore on the trunk of a tree at Taban Valley, BTNR on 18 March 1996 ( Leong et al. 1996), T. horridum has only been recorded an additional eight times (Figueroa & Selveindran 2011). The subsequent five observations were all made before July 1997 and featured individuals perched on tree trunks at Taban Valley (Teo & Rajathurai 1997; Figueroa & Selveindran 2011). The seventh record of T. horridum did not come until 12 years later on 29 January 2009 when Leong saw one sitting on a leaf, also at the same location (Figueroa & Selveindran 2011). The last reported sighting occurred two years later on 20 July 2011, when a single individual was seen on a tree trunk at NSSF ( Fig. 7F ), representing a new locality for T. horridum (see Figueroa & Selveindran 2011). Teo & Thomas (2019) incorrectly cited Figueroa & Selveindran (2011) as recording a specimen in BTNR. Clearly, from these observations T. horridum prefers trunks of large trees as noticed in Malaysia where they nest in phytotelmata (Grismer 2011; Stuebing et al. 2017). Stuebing et al. (2017) postulated that T. horridum is not such a rare species, but is seldom detected owing to its exceptional camouflage. Coupled with its requirement for mature forests (Grismer 2011), we suspect that T. horridum in Singapore has yet to recover from the initial island-wide deforestation and loss of large trees.

Occurrence. Restricted, only known from BTNR and NSSF. Rare.

Singapore conservation status. Critically Endangered.

Conservation priority. Highest.

IUCN conservation status. Least Concern [2021].

LKCNHM & NHMUK Museum specimens. Bukit Timah Nature Reserve : ZRC.1.3278 (18-Mar-1996) .

Additional Singapore museum specimens. No specimens.

Singapore localities. Bukit Timah Nature Reserve—Nee Soon Swamp Forest.

Class Reptilia Laurenti, 1768 (135 species)

Reptilia Laurenti, 1768: 17.

Order Crocodylia Owen, 1842 (1 species)

Crocodilia Owen, 1842: 65 .

Family Crocodylidae Gray, 1825 (1 species)

Crocodilidae Gray, 1825: 195 (type genus Crocodylus Laurenti, 1768 ).

Genus Crocodylus Laurenti, 1768 (1 species)

Crocodylus Laurenti, 1768: 53 (type species: Crocodylus niloticus Laurenti, 1768 , by subsequent designation by A.E. Brown, 1908: 113; gender masculine).

Figures

FIGURE 7. A) Pulchrana laterimaculata, B) Sylvirana guentheri, C) Leptomantis cyanopunctatus, D) Nyctixalus pictus, E) Polypedates leucomystax, F) Theloderma horridum, G) Crocodylus porosus, and H) Caretta caretta. Photographs by: Alex Figueroa [A–B, D–F], Marcus A.H. Chua [C], Jensen G.H. Seah [G], and Kelvin K.P. Lim [H].