National recovery plan for Stream Frogs of South-east Queensland 2001-2005
Prepared by Harry Hines
Queensland Parks and Wildlife Service
and the South-east Queensland Threatened Frogs Recovery Team, 2002
Appendix 1. Species Profiles
Southern Dayfrog Taudactylus diurnus Straughan and Lee 1966
- Current distribution
- Conservation status
Small diurnal frog, males 22.0-27.2mm, females 23.3-30.6mm snout-vent length (Liem and Hosmer 1973). Dorsal surface is grey or brown with darker mottling. There is a pale bar between the eyes, bordered behind by a dark brown patch. A short dark stripe runs from the eye to the base of the forearm, sometimes with a pale band bordering the lower edge. A dark, irregular, slightly raised H-shaped mark is present over the shoulders, and an irregular pale patch may be present over the pelvic region. The limbs have irregular dark cross-bands. The ventral surface is cream, yellowish-white or blue-grey, with or without grey spots. The throat is more heavily spotted or mottled with grey, sometimes appearing grey with yellow spots. Its skin is smooth, finely granular, or with a few low warts above and is smooth below. The digits have wedge-shaped discs and are unwebbed, though toes have broad fringes. (Cogger 1996, Liem and Hosmer 1973, Straughan and Lee 1966).
Although the species lacks vocal sacs, a call is emitted which resembles a soft chuckling, repeated 1-2 or 4-5 times in quick succession every 4-5 mins, reminiscent of T. eungellensis and the chuckle call of T. acutirostris (Ingram 1980, Liem and Hosmer 1973, McDonald pers. obs.).
Active T. diurnus have been observed year round, although less frequently during cooler winter months (Czechura and Ingram 1990). Breeding occurs in warm weather, after or during heavy rain, between October and May, peaking in the January to March period (Czechura and Ingram 1990, Straughan and Lee 1966). Amplexus is inguinal and the eggs are deposited in gelatinous clumps under rocks in the water (Czechura and Ingram 1990). The tadpoles may be found year round and are bottom dwellers, feeding by scraping food from the substrate (Liem and Hosmer 1973).
Tadpoles are moderately sized, with an umbrella-shaped lip, with the labial papillae completely surrounding the labium. There are no labial teeth (Liem and Hosmer 1973).
Taudactylus diurnus inhabits montane rainforest, tall open forest and other riparian vegetation with a closed understorey along permanent and temporary streams at elevations between 350 and 800m (Czechura and Ingram 1990). It prefers permanent streams with a rocky substrate, but will use streams with a wide variety of substrates provided the water is not very muddy (Czechura and Ingram 1990). Active frogs may be found amongst low vegetation, rocks, leaf litter and other debris, generally within 10m of water, although they have been recorded more than twice this distance from water in wet weather (Czechura and Ingram 1990). Individuals have frequently been observed to enter water, swimming from point to point or sitting half-submerged (Czechura and Ingram 1990). At night they shelter under rocks and debris or within crevices (Czechura and Ingram 1990).
Taudactylus diurnus is a diurnal species. Activity begins at sunrise and ceases soon after sunset (Ingram 1980). This species is generally very active, but will sit motionless for periods while basking in sunlit patches or on warm rocks (Czechura and Ingram 1990). Individuals escape danger by leaping into the water and swimming away, or hiding on the bottom amongst rocks or mud (Czechura and Ingram 1990). Activity in T. diurnus appears to be restricted by temperature, and it is intolerant of desiccation (Johnson 1971).
Occurred in disjunct populations in the Blackall, Conondale and D'Aguilar Ranges south-east Queensland, from Coonoon Gibber Creek in the north to Mount Glorious in the south (26° 33'S, 152° 42'E - 27° 23´S, 152° 47´E) (Hines et al. 1999) (Figure 4).
|Figure 4. Distribution of southern dayfrog Taudactylus diurnus.
Shaded areas are: light grey - State forest or timber reserve, dark grey - national parks and conservation parks. Some towns and larger streams are shown.
Not sighted in the wild since 1979 despite continued efforts to relocate it. Since Ingram and McDonald's (1993) review, the following surveys and monitoring for the species have been undertaken (summarised by Hines et al. 1999):
- T. diurnus was present at most sites at which R. silus occurred, so surveys and monitoring for that species (see above) were likely to detect T. diurnus.
- Regular (near fortnightly) diurnal monitoring at the type locality (Greene's Falls) and nearby streams at Mount Glorious by Brisbane Frog Society for a year (1995-1996).
- A study of L. pearsoniana at the head of Love Creek at Mount Glorious, since September 1995, failed to detect T. diurnus despite some diurnal censuses and regular tadpole surveys.
As is the case for R. silus, the reason(s) for the disappearance for T. diurnus remains unknown (Martin, McDonald and Hines 1997). Its habitat is currently threatened by feral pigs, invasion of weeds (especially mist flower) and altered flow and water quality due to upstream disturbances.
It is listed as Presumed Extinct nationally, and as Endangered in Queensland and in the Action Plan. Taudactylus diurnus meets IUCN (2001) criteria for Presumed Extinct.