Eungella dayfrog
Common name: Eungella dayfrog
Scientific name: Taudactylus eungellensis Liem and Hosmer, 1973
Family: Myobatrachidae (Australian water frogs)
Endemicity: Queensland endemic
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999). It is considered a medium priority under the Department of Environment and Resource Management 'Back on Track' species prioritisation framework.
Description
Size (SVL): males 23.8-32mm, females 25.5-37.11mm (R. Retallick in McDonald and Alford 1999). Weight: males 0.8-3.7g, females 1.9-5g (R. Retallick in McDonald and Alford 1999).
T. eungellensis is a small frog, with a bluntly acuminate snout. The dorsal surface may be yellowish tan to dark brown, with irregular dark brown markings. A broad band crosses the head between the eyes, with two other anterior to this. A black band extends from behind the eye to the base of the fore arm, and there is a prominent irregular X-shaped marking on the back.
There are cross-bands on the limbs and digits. The throat and abdomen are white or cream-coloured, and the ventral surfaces of the limbs are bright yellow, with or without dark brown spots. The skin is shagreened with tubercles above, the postero-medial portion of the thighs is granular, and the ventral surface is smooth. The fingers and toes have expanded tips, and are broadly fringed but lack webbing. Males have finely spinulated, rounded nuptial pads like a blister on the back of the hand at the base of the second and third fingers. Males do not possess a vocal sac. The typanum is hidden. (Liem and Hosmer 1973, Cogger 2000).
Habitat and distribution
Taudactylus eungellensis inhabits exposed rocky sections in the splash zones of riffles, cascades and waterfalls of rainforest streams. They may be found under rocks and crevices or in more exposed positions (Liem and Hosmer 1973, McDonald 1990, McNellie and Hero 1994). The tadpoles are benthic, inhabiting mid-stream pools or partially connected stream-side pools (Retallick & Hero 1998).
Former: T. eungellensis is restricted to a small area of the Clarke Range, mid-east Queensland at altitudes of 200-1000m (Covacevich and McDonald 1993).
Current: T. eungellensis has undergone a rapid and dramatic range contraction, and after a period of apparent absence, has now been located at nine sites within its former distribution (McNellie and Hero 1994, R. Retallick pers. comm.). It is found in Eungella National Park.
Latitude: Between 20&186; 48' and 21&186; 13';
Longitude: Between 148&186; 9' and 148&186; 43'
Life history and behaviour
Calling has been heard during most months of the year with the greatest intensity during spring and summer. The call is a gentle rattling sound barely audible over the sound of rushing water (Winter and McDonald 1986). T. eungellensis is largely diurnally active with calling during the day, though males will call at night (McDonald 1990, McNellie 1994). They bask on exposed rocks, and when disturbed escape into the water, remaining submerged on the bottom for some time (Couper 1992, Liem and Hosmer 1973). Males have been observed communicating by visual cues, which include flicking and waving of legs, head bobbing, and distinctive hops.
T. eungellensis is a late summer breeder and oviposition occurs from November to May (Liem and Hosmer 1973, McDonald 1990). Females lay 30-50 large (2.2 - 2.6 mm) eggs under rocks in the water (Liem and Hosmer 1973). The tadpoles do overwinter (McDonald 1990, Retallick & Hero 1998). Metamorphosis occurs between November and January (Retallick & Hero 1998).
The tadpole is orange brown, with a distinctive V-shaped marking behind the eye, and dark pigment around the base of the tail and upper surface of the tail muscle. The body is oval and the fins clear and narrow, with a rounded tail tip. The spiracle is sinistral, the vent dextral. The oral disc is small and completely surrounded by a single row of small marginal papillae, with the posterior edge of the papillae skirt indented toward the mouth medially. There are no labial teeth, but there are 3 papillar ridges on the posterior labium. Keratinous jaws pigmented, small and weak (Liem & Hosmer 1973; Retallick & Hero, 1998). The tadpoles are bottom dwellers in pools and slow flowing sections of rainforest steams.
Threatening processes
Taudactylus eungellensis is one of two species of frogs occurring in upland rainforest streams in mid-east Queensland which have undergone substantial population decline (McDonald 1990, Ingram and McDonald 1993).
The species was considered common across its range, occurring in large numbers (up to ten per square metre) over long stretches of streams at high and low altitude (McDonald 1990, M. Mahony pers. comm.). T. eungellensis disappeared from lower altitudes in January 1985, and by June 1986 adults could not be found despite repeated visits to monitored sites (Winter and McDonald 1986). Tadpoles could still be found in the southern parts of its distribution until May 1987 (McDonald 1990). Periodic searches continued unsuccessfully until July 1992, when an adult was caught and photographed (Couper 1992). Subsequent searches between November 1993 and August 1998 have located small numbers of adults, subadults, metamorphs and tadpoles at nine sites within Eungella National Park (McNellie and Hero 1994, R. Retallick and J.M. Hero pers. comm).
The causes of the population decline remain unknown. McDonald (1990) found no obvious evidence that seasonal rarity, over-collecting, drought, floods, habitat destruction, disease, heavy parasite loads or stress due to handling and data collection were responsible for the population declines.
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 the James Cook University website.
Recovery actions
The recovery plan makes the following management recommendations for the conservation of stream-dwelling frogs of the Wet Tropics bioregion:
- Monitor sites where species were recorded historically to detect recovery of the species.
- Investigate disease in preserved specimens and other species occupying similar habitat.
- Continue studies on the autecology of this species.
- Train park staff and community volunteers in identification of this species.
- Implement monitoring by park staff of select locations within the national park estate where R. vitellinus formerly occurred.
Last reviewed 23 February 2011
Last updated 26 July 2010