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Nyctixalus pictus
(Image taken by Kenny Heng, 2011.)
Nyctixalus pictus (Peters, 1871)

Nyctixalus pictusis a small nocturnal tree frog species which lives in terrestrial forests and breeds in tree cavities. It has been found breeding in old pitcher plants and its tadpoles have even been found in a rotting hollow fruit containing water.
Adults have been found perching on leaves of shrubs and small trees 1-3 metres above ground, and can probably be found in higher levels.
Thus these frogs are difficult to find, but you may hear them calling to each other when walking in the forests at night.

Name

Binomial: Nyctixalus pictus (Peters, 1871)
Vernacular: Cinnamon tree frog, Cinnamon bush frog, Cinnamon frog, Spotted tree frog, Painted Indonesian Treefrog, Sumatra Indonesian Treefrog

Etymology

“Pictus” is a latin word which has the meanings of painted, coloured, and variegated, most likely referring to the attractive colours of this species. Other organisms with the specific name pictus, like the African Wild Dog (Lycaon pictus) and the Pictus Cat (Pimelodus pictus), are usually attractively coloured.


Diagnosis

The distinguishing characteristic of this species is its unique colouration, but can be confused with the similarly coloured Nyctixalus spinosus in the Philippines where their ranges overlap. However, Nyctixalus pictus occurs at lower elevations, has fewer tubercles (which are numerous in Nyctixalus spinosus) and lacks cranial and supratympanic crests. (Alcala & Brown, 1998)
It also has a similar colouration as the rare Nyctixalus margaritifer, which is endemic to Java, Indonesia. Nyctixalus margaritifer is larger (males grow to around 45 mm) and has spinose tubercles across the throat, which are absent in Nyctixalus pictus (Inger, 1966).

Description

Adult

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Image taken by Daniel Ng. 10 Aug 2009.

Colouration

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Image by Chan Kwok Wai, 29 Aug 2008.

shobster-edit.jpg
Image taken by Shobster, 09 Jun 2009. (Permission pending)

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Image taken by Eric Pui Yong Min, 12 Nov 2005. (Permission pending)

Adults are distinctively coloured light brown or bright-reddish orange with small whitish spots all over their back and limbs. These spots "form a broken line from the edge of the snout, along the edge of the upper eyelid, and continue partially down the side of the back" (Inger, 2005). The spots are usually on the tubercles (small spiny bumps). (Inger, 1966)
Their ventral surfaces are white, and may or may not be with greenish black blotches. (Inger, 1966)
Head
Head is longer than broad, with a relatively long snout. Lack vomerine teeth at the roof of their mouths.
Eye: The upper half of their iris is white, while the lower half is brown. (A paper by Glaw & Vences discussing the various hypotheses regarding the possible functions of distinct and colourful anuran iris colouration can be found in this link )
Tympanum (Ear Drum): The tympanum is visible, about 2/3 of the eye diameter.

Skin

Rough skin with many distinct granular tubercles on forehead, back and limbs. Skin of throat is smooth, while skin of belly is coarsely granular. 2-6 whitish tubercles are found above and below vent. (Inger, 1966)

Limbs

They have long and slender hind limbs. (Inger, 1966)
Like other aboreal frogs, Nyctixalus pictushas the tips of fingers and toes expanded into round or oval disks. These disks are smaller than the tympanum, and disks of toes smaller than those of outer fingers. (Inger, 1966)
Fingers do not have webbing while toes are half-webbed. (Inger, 1966)

Sexual dimorphism


Male
Female
Length
Measure 30-33 mm from snout to vent. (Inger, 1966)
Slightly larger, measuring 31-34 mm. (Inger, 1966)
Nuptial pads
Yellowish nuptial pads are present in the centre of the first finger's dorsal surface.
These nuptial pads are used to hold on to the female during mating. (Inger, 1966)
No nuptial pads present.

Call

From field observations, they have various calls. Its call has been described as a "muffled tweet" (Das, 2007) and "a soft "poop"" (Baker & Lim, 2008).

Call of Nyctixalus pictus. Recording taken by Christopher Puan.

Amplified call of Nyctixalus pictus. Original recording taken by Kelvin Lim.

Call of Nyctixalus pictus in captivity. Video recorded by bigeyesworld.com.

Larva

Body: It has a dark brown oval body (with a lighter ventral side). Its body is dorsoventrally flattened , more so than other Rhacophorid tadpoles. (Inger, 1985)
Eyes: Its eyes are dorsally positioned (i.e. on top of its head) and cannot be seen from below. Its maximum width is just behind its eyes. (Inger, 1985)
Gill chambers: Tadpoles has 3 gill chambers on each side, with its inner one greatly reduced. (Inger, 1985)
Fins and tail: Its fins are dark, but a lighter colour compared to its tail. The tail is the same colour as the body and is slightly more than half its total length and has a rounded tip. (Inger, 1966)

Biology

Habitat

Nyctixalus pictus can be "found in primary and old secondary forests, in flat and hilly terrain, from near sea level to 1650 metres." (Inger & Stuebing, 2005)

Feeding habits

Nyctixalus pictus diet is made up of invertebrates, and it has been "known to eat orthopterans and thysanurans". (Das, 2007)

Reproduction

Females do not lay many eggs, with gravid females found to carry sets of oviducal eggs with 7-14 eggs. (Das, 2007)
Eggs and tadpoles are usually found in tree cavities which hold water. These trees are always larger than 30 cm in diameter. (Inger & Stuebing, 2005) The frogs attach their eggs to walls of tree cavities with large amounts of gelatin and the tadpoles drop into the water upon hatching, where they will complete their development into adults. (Inger, 1966)

Distribution

International Union for Conservation and Natural Resources (IUCN) Red List states that Nyctixalus pictus has been found “from Yala in extreme southern Thailand (Taylor, 1962), through Peninsular Malaysia (Berry, 1975), Singapore (Lim and Lim, 1992), Sumatra (including Siberut in the Mentawai Islands) in Indonesia, northern parts of Borneo (both Malaysia and Indonesia), and Palawan in the Philippines.” It also states the likelihood of it having a wider range than what current records suggest
In Singapore, Nyctixalus pictus appears to be found only in the Central Nature Reserve, including Bukit Timah Nature Reserve and Nee Soon swamp forest. (Baker & Lim, 2008)

Conservation status

It is listed as “Vulnerable” in the 2008 Singapore Red Data Book (Davidson et al., 2008), while the IUCN Red List listed it as “Near Threatened”, despite its relatively wide distribution range, since the area and quality of its habitats are declining rapidly due to extensive forest loss within its range (Diesmos et al., 2004).
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Recorded distribution of Nyctixalus pictus.
Original image by IUCN Red List.

Taxonavigation

Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Rhacophoridae
Genus: Nyctixalus

This species had been previously put into the Ixalus and Philautus genus (Inger, 1966). However these classifications are now considered invalid. Hence when searching for old records of this species, it is wise to do a search for Ixalus pictus and Philautus pictus as well.

Type Information

Nyctixalus pictus was first described as Ixalus pictus by W.C.H. Peters in 1871 in German.
Its holotype, which is the representative specimen used to describe a new species/subspecies, is currently stored at Museo Civico di Storia Naturale di Genova “Giacomo Doria”, Via Brigata Liguria 9, 16121 Genova, Italy. (Its description by Peters can be found here.)
Holotypes and their descriptions are very important as they will be referred to whenever there are arguments about the species' classification and is the name-carrier for the species.

Literature and References

Alcala, A. C. & Brown, W. C.,1998. Philippine Amphibians: Illustrated Field Guide. Bookmark, Inc., Philippines.
Baker, N. & Lim, K., 2008. Wild animals of Singapore: A photographic guide to mammals, reptiles, amphibians and freshwater fishes. Draco Publishing and Distribution, Nature Society (Singapore), Singapore. P. 60.
Berry, P.Y., 1975. Family Rhacophoridae. The Amphibian Fauna of Peninsular Malaysia. Tropical Press, Kuala Lumpur. Pp. 90-109.
Capocaccia, L. 1957. Catalogo dei tipi di anfibi del Museo Civico di Storia Naturale di Genova. Annali del Museo Civico di Storia Naturale di Genova. Serie 3, 69: 208-222.
Das, I., 2007. Amphibians and Reptiles of Brunei. Natural History Publications (Borneo), Kota Kinabalu. P.69.
Davison, G.W.H., Ng, P.K.L. & Ho, H.C (Eds.). 2008. The Singapore Red Data Book (2nd Edition). Nature Society (Singapore), Singapore. 285pp.
Diesmos, A., Alcala, A., Brown, R., Afuang, L., Gee, G., Sukumaran, J., Norsham Yaakob, Leong, T.M., Chuaynkern, Y., Thirakhupt, K., Das, I., Iskandar, D., Mumpuni, Inger, R., Stuebing, R., Yambun, P. & Lakim, M., 2004. Nyctixalus pictus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.1. <www.iucnredlist.org>. Accessed on 20 October 2011.
Inger, R. F., 1985. Tadpoles of the Forested Regions of Borneo. Fieldiana: Zoology 26: 1-108
Inger, R. F., 1966. The Systematic and Zoogeography of the Amphibian of Borneo. Fieldiana: Zoology 52: 1-402
Inger, R. F. & Stuebing, R. B., 2005. A field guide to the frogs of Borneo. Natural History Publications (Borneo), Kota Kinabalu. Pp. 159-160
Iskandar, D. & Mumpuni, 2004. Nyctixalus margaritifer. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. www.iucnredlist.org. Accessed on 20 October 2011.

“Spotted Tree Frog on a fern leaf,” by Chan Kwok Wai. Flickr.com, 07 Sep 2008. URL: http://www.flickr.com/photos/kwokwai76/2836508016/in/photostream (accessed on 20 Oct 2011).

Other Species Pages
Encyclopedia of Life
Frogs of Borneo
NParks Flora & Fauna Hub

Comments

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