Southern dayfrog
Taudactylus diurnus Straughan and Lee, 1966
Queensland Legislative Status: Endangered
Endemicity: Queensland endemic
Description: Small diurnal frog, males 22.0-27.2mm, females 23.3-30.6mm SVL (Liem & Hosmer 1973). Dorsal surface is grey or brown with darker mottling. A pale bar between the eyes, bordered behind by a dark brown patch.
Short dark stripe runs from the eye to the base of the forearm, sometimes with a pale band bordering the lower edge. Dark, irregular, slightly raised H-shaped mark is present over the shoulders, and an irregular pale patch may be present over the pelvic region. Limbs have irregular dark crossbands. Ventral surface is cream, yellowish-white or blue-grey, with or without grey spots. Throat is more heavily spotted or mottled with grey, sometimes appearing grey with yellow spots. Skin is smooth, finely granular, or with a few low warts above, smooth below. Digits have wedge-shaped discs and are unwebbed, though toes have broad fringes. (Cogger 2000, Liem & Hosmer 1973, Straughan & Lee 1966).
Call: Although lacking vocal sacs, a call is emitted and 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 & Hosmer 1973, McDonald pers. obs.).
Tadpoles: Tadpoles are moderately sized, with an umbrella-shaped lip, with the labial papillae completely surrounding the labium. There are no labial teeth (Liem & Hosmer 1973).
Reproduction: Active T. diurnus have been observed year round, although less frequently during cooler winter months (Czechura & Ingram 1990). Breeding occurs in warm weather after or during heavy rain between October and May, peaking in the January to March period (Czechura & Ingram 1990, Straughan & Lee 1966). Amplexus is inguinal and the eggs are deposited in gelatinous clumps under rocks in the water (Czechura & Ingram 1990). The tadpoles may be found year round and are bottom dwellers, feeding by scraping food from the substrate (Liem & Hosmer 1973).
Habitat: T. 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 & 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 & Ingram 1990). Active frogs may be found among low vegetation, rocks, leaf litter and other debris, generally within 10m of water, although they have been recorded about 22m from water in wet weather (Czechura & Ingram 1990). Individuals frequently enter the water, swimming from point to point or sitting half-submerged (Czechura & Ingram 1990). At night they shelter under rocks & debris or within crevices (Czechura & Ingram 1990).
T. diurnus is a diurnal species, activity beginning at sunrise and ceasing 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 & Ingram 1990). Individuals escape danger by leaping into the water and swimming away, or hiding on the bottom among rocks or loose mud (Czechura & Ingram 1990). T. diurnus activity appears to be restricted by temperature, and this species is intolerant of desiccation (Johnson 1971).
Distribution: T. diurnus is the southern-most representative of the genus, occurring in three sub-coastal ranges (Blackall, Conondale & D'Aguilar Ranges) near Brisbane, south-eastern Queensland (Hines et al 1999). T. diurnus has not been seen sighted in the wild since 1979 and may be extinct. Continued efforts to relocate the species have failed.
Latitude: Between 26&186; 34' and 27&186; 20';
Longitude: Between152&186; 34' and 152&186; 53'.
National Parks: D'Aguilar, Conondale Range, Kondalilla falls
Threatening Processes: The causes of the population decline remain unknown. Tyler & Davies (1985) found no obvious evidence that over-collecting, pollution from logging or gold panning, or drought were responsible for the population decline of the closely associated R. silus. Ingram (1990) argued that the disappearances might be due to late rains falling in the cooler months.
Current research is examining the possibility that a disease may have caused the decline of this species (Berger et. al. 1999). Information on disease investigations and management can be located at http://www.jcu.edu.au/school/phtm/PHTM/frogs/ampdis.htm.
Status: T. diurnus is one of five species of upland rainforest stream-dwelling frog which has declined in south-east Queensland during the last 20 years (Ingram & McDonald 1993). It underwent a sudden and unanticipated decline during the late 1970's, the last specimen reported in 1979 (Czechura & Ingram 1990). Regular searches since that date have failed to rediscover it - most recently in November 1999 (Ingram & McDonald 1993, Hines et al 1999, H. Hines unpubl).
Management Recommendations: Recovery Plan for Rheobatrachus silus and Taudactylus diurnus by Wayne E. Martin, Keith R. McDonald and Harry B. Hines1997 recommends the following actions:
1. Ongoing survey of historical sites and sites with suitable habitat.
2. Provision of public information and education to raise awareness regarding this species.
References:
Cogger, H.G. 2000. Reptiles and Amphibians of Australia. Reed New Holland: Sydney.
Covacevich, J.A. & McDonald, K.R. 1993. Distribution & conservation of frogs and reptiles of Qld rainforests. Memoirs of the Qld Museum. 34(1):189-199.
Czechura, G.V. & Ingram, G.J. 1990. Taudactylus diurnus & the case of the disappearing frogs. Memoirs of the Qld Museum. 29(2):361-365.
Hines, H., Mahony, M and McDonald K.R. 1999. An Assessment of Frog Declines in Wet Subtropical Australia. In Campbell, A (ed), 'Declines and Disappearances of Australian frogs'.(Environment Australia, Department of the Environment and Heritage: Canberra). 234 pp.
Ingram. G. 1980. A new frog for the genus Taudactylus (Myobatrachidae) from mid-eastern Qld with notes on the other species of the genus. Memoirs of the Qld. Museum. 20(1):111-119.
Ingram,G.J. & McDonald, K.R. 1993. An update on the decline of Qld's frogs. Pp 297-303 In Lunney, D. & Ayers, D. (eds) Herpetology in Australia. A Diverse Discipline. Royal Zoological Society of NSW, Mosman.
Liem, D.S. & Hosmer, W. 1973. Frogs of the genus Taudactylus with descriptions of two new species (Anura: Leptodactylidae). Memoirs of the Qld Museum. 16(3):459-470.
Straughan, I.R. & Lee, A.K. 1966. A new genus and species of leptodactylid frog from Qld. Proceedings of the Royal Society of Qld. 77(6):63-66.
Last updated: 30 August 2005