Australian Ground Frogs (Limnodynastidae)

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Australian ground frogs

(Limnodynastidae)

Class Amphibia

Order Anura

Family Limnodynastidae

Thumbnail description
Small to large frogs that range from rotund burrowing forms to terrestrial species with powerful legs

Size
0.9–4.3 in (22–108 mm)

Number of genera, species
9 genera; 48 species

Habitat
These frogs are wide ranging, from arid habitats to the wet/dry tropics to temperate and subtropical zones with summer or winter peaks in rainfall and in all vegetation types found within these climatic areas

Conservation status
Critically Endangered: 1 species; Endangered: 2 species; Vulnerable: 2 species; Lower Risk/Near Threatened: 1 species; Data Deficient: 1 species

Distribution
Australia (including Tasmania) and New Guinea

Evolution and systematics

Based on studies of the ilium from disarticulated material, three extant genera, Limnodynastes, Lechriodus, and Kyarranus have been recorded from the Oligo-Miocene, and Lechriodus also has been recorded from the early Eocene. The extant species Limnodynastes ornatus has been recorded from a Quaternary site. Other Limnodynastes material has been recorded from a Plio-Pleistocene site and Neobatrachus from the Miocene/Pliocene boundary. Lechriodus is well represented in material from the Riversleigh site in northwestern Queensland, Australia, and its occurrence in the Tertiary helps explain the current disjunct distribution of the genus, with four species in New Guinea and a single representative in southeastern Queensland. No subfamilies are recognized.

The Australopapuan ground frogs have had a checkered taxonomic and phylogenetic history that remains the subject of debate. Early workers, such as Cope, placed individual genera in several families, but the seminal work of Parker in 1940 recognized the frogs as two subfamilies of the Leptodactylidae. The Myobatrachinae and Cycloraninae were defined clearly, on the basis of numerous skeletal and myological features. Within the Cycloraninae were the recognized genera Adelotus, Cyclorana, Heleioporus, Lechriodus, Limnodynastes, Mixophyes, Notaden, and Philoria. Cyclorana later was shown to be a hylid genus, and the subfamily became the Limnodynastinae. Heleioporus was split into the nominate genus and Neobatrachus; and Kyarranus was recognized as a new genus with affinities to Philoria.

Megistolotis was described in 1979 but has since been made synonymous with Limnodynastes. The problematic genus Rheobatrachus was described in 1973, and it has been allied variously with the Limnodynastinae, the Myobatrachinae, or its own subfamily, Rheobatrachinae, or family Rheobatrachidae. Mixophyes has posed problems in the acceptance of monophyly of the Limnodynastinae. The Myobatrachidae inclusive of all genera formerly assigned to the Limnodynastinae and Myobatrachinae was recognized in 1973 on the basis of geographical distribution. Monophyly of the Myobatrachidae with or without Rheobatrachus or Mixophyes or both has been challenged, though the data used are old and not always substantiated by later studies. Familial status as recognized here must remain subject to debate and further analysis with new data. Mixophyes currently is placed within the Limnodynastidae, but the genus does not share many of the features that unite the lineage. For example, they engage in axillary amplexus,

their tongue muscles differ, and the first two vertebrae are not fused.

Physical characteristics

In all Limnodynastidae (except Mixophyes) the first two vertebrae are fused. The alary (wing-like) processes of the hyoid are on stalks, though the actual shape of these processes can vary. The superficial jaw muscle, the M. intermandibularus, underlies the M. submentalis, and the cricoid ring is complete.

Some genera or species groups (e.g., Notaden, Neobatrachus, Heleioporus, Limnodynastes dorsalis, and L. ornatus groups) are burrowers and exhibit the burrowing morphotype of short limbs, short heads, and rotund bodies. Others are more streamlined and have powerful hind limbs (e.g., Mixophyes), and still others (e.g., the Limnodynastes tasmaniensis group) have a body form that is intermediate between these extremes.

Foam-nesting species (except Heleioporus) exhibit seasonal development of flanges on the second and third fingers in females. Nuptial excrescences in males vary from heavily spinous structures on the thumb and second finger (e.g., Heleioporus and Limnodynastes lignarius) to glandular pads that may be restricted to the base of the thumb, found solely on the thumb and second fingers (e.g., Limnodynastes spenceri), or extend to three fingers (e.g., L. ornatus.).

Many species are dull brown or gray, but others have red or gold marks on the thighs or brilliantly colored labial glands. Still others have spectacular dorsal markings of yellow superimposed with black and red warty markings in the form of a cross (e.g., Notaden bennettii).

Distribution

Lymnodynastids occur throughout Australia. Limnodynastes convexiusculus also inhabits southern New Guinea, and a single species of Mixophyes (M. hihihorlo) and four species of Lechriodus occur in New Guinea.

Habitat

These frogs inhabit arid desert and seasonally arid grasslands, woodlands, and open forest; they are found along perennial and ephemeral (temporary) streams and around permanent and ephemeral ponds from sea level to elevations above the snow line.

Behavior

Seasonal activity is governed by the availability of moisture. All limnodynastids are crepuscular or nocturnal. Many limnodynastids burrow to avoid dry conditions. All burrow backward, but in one of two ways. Backward-sliding burrowers shuffle with the hind limbs and descend at an angle to the surface, whereas circular burrowers corkscrew vertically downward, turning themselves around as they descend. The different forms of burrowing are associated with differences in muscle mass in the lower hind legs. Of the burrowing species, members of the genera Neobatrachus and Heleioporus form cocoons and reduce evaporative water loss dramatically while estivating underground. Burrowing species resorb water from the bladder to maintain water balance during their subterranean periods. Adelotus brevis engages in male-male combat, but encounter calls are used by other species to maintain calling sites.

Feeding ecology and diet

The diet is arthropod-based, but it is restricted by the gape of the mouth and by seasonal availability of prey items. The form of the tongue governs whether animals capture prey by biting or by tongue flicking.

Reproductive biology

Marked differences in breeding seasons are common. Many species, in particular most of the burrowing species, are explosive breeders. They come to the surface in response to heavy rain and breed in temporary pools. Others are strictly seasonal, and still others (e.g., Limnodynastes tasmaniensis) breed continuously if conditions are right.

Calls vary considerably, from clicks (e.g., Limnodynastes tasmaniensis) to whoops (e.g., Heleioporus, Notaden) to trills (e.g., some Neobatrachus). The complex calls of the amazing repertoire emitted by many Australian hylid frogs are lacking in the ground frogs. Calling is nocturnal in the group.

The Limnodynastidae have highly varying forms of egg deposition. Some frogs produce eggs in jelly that are laid in water (e.g., Neobatrachus and Notaden); others produce eggs in jelly that are deposited out of water. The tadpoles enter the stream on hatching (Mixophyes). All species of Limnodynastes, Lechriodus, and Adelotus produce a foam nest in water, though some Limnodynastes tasmaniensis in southern South Australia lay eggs that are not in a foamy mass. Heleioporus lays eggs, also in a foamy mass, in a burrow that, on flooding, releases tadpoles into the water. The other foam-nesting species, Philoria and Kyarranus, lay their eggs either out of water or in shallow water, and the nonfeeding tadpoles develop in the broken-down foam and jelly mass.

Conservation status

Philoria frosti is listed as Critically Endangered by the IUCN; Mixophyes fleayi and M. iteratus as Endangered, M. balbus and Heleioporus australiacus as Vulnerable; Adelotus brevis as Lower Risk/Near Threatened; and Notaden weigeli as Data Deficient. Reasons for declines have not been identified positively, though Mixophyes may have been decimated by chytrid fungus. Philoria is an alpine species that is threatened by skifield development as well as unidentified factors that are causing declines elsewhere in the Australian Alps.

Significance to humans

Some burrowing species, such as Notaden bennettii, have been recognized as a source of water to aboriginal people living in arid areas. Skin secretions have been investigated for pharmacological activity, and an unidentified toxic substance has been recorded in Heleioporus.

Species accounts

List of Species

Tusked frog
Woodworker frog
Giant barred frog
Painted frog
Northern spadefoot toad
Baw Baw frog

Tusked frog

Adelotus brevis

taxonomy

Cryptotis brevis Günther, 1863, Clarence River, New South Wales, Australia.

other common names

None known.

physical characteristics

In this medium-size, sexually dimorphic species, males are larger than females, which is unusual. Males are 1.3–1.7 in (34–44 mm), and females are 1.1–1.5 in (29–38 mm). The head of the male is broad and flat with two large tusks on the lower jaw. The head of the female is not as expanded posteriorly, and the tusks, if present, are small. The ventral surface of both males and females is pigmented heavily with strong white marbling; the groin and the back of the hind legs are bright red. Fingers and toes are basally webbed.

distribution

This species occurs on the Great Dividing Range and the coast from central and eastern Queensland to the southern coast of New South Wales, Australia.

habitat

This species inhabits temperate rainforest or wet sclerophyll forest floor and sometimes is found in open grasslands.

behavior

Male combat occurs at calling sites; the tusks are used to attack rivals.

feeding ecology and diet

Males tend to eat more snails and fewer arthropods than do females, a dietary divergence related to habitat separation of male and female frogs. Males usually spend more time in moist habitats, where snails are abundant, whereas females are apt to be found on the drier forest floor, where arthropods are more abundant.

reproductive biology

The call is a single repeated "cluck." Females lay unpigmented eggs in foam nests in still water. Males remain with the foam nest after deposition. Tadpoles are ovoid to elliptical in shape, with shallow fins, and they seem to feed on detritus.

conservation status

Listed as Lower Risk/Near Threatened. Some mortality in Brisbane has been attributed to chytrid fungus. Loss and degradation of habitat may be a threat.

significance to humans

None known.

Woodworker frog

Limnodynastes lignarius

taxonomy

Megistolotis lignarius Tyler Martin, and Davies, 1979, 4 mi (6.5 km) north of Lake Argyle Tourist Village on Kununnura and Lake Argyle Road, Kimberley Division, Western Australia.

other common names

English: Carpenter frog.

physical characteristics

This moderately large frog is characterized by an extremely large tympanum, a broad head, and an extensive row of vomerine teeth. The males are 1.7–2.4 in (43–62 mm), and the females are 1.9–2.4 in (47–61 mm). Males have muscular forelimbs and spiny nuptial pads on the thumb and second finger.

distribution

This species is confined to escarpment country in the Kimberley Division of Western Australia and the Northern Territory.

habitat

The frog inhabits scree slopes and escarpments near ephemeral or perennial streams.

behavior

The frogs take shelter in caves and crevices during the dry season and emerge to mate during the wet season.

feeding ecology and diet

Nothing is known of the feeding ecology or diet of this species, but it probably feeds on arthropods.

reproductive biology

Males call from concealed locations beneath rocks or vegetation beside streams. The call is a soft tap similar to the sound of wood being struck. Females lay a foam nest of unpigmented eggs beneath vegetation or rocks. The eggs hatch into darkly pigmented tadpoles with ventral suctorial mouths adapted to the fast-flowing streams. Tadpoles actively seek out riffles in the stream and usually are found in the fastestflowing sections.

conservation status

Not threatened. The species is secure across its range.

significance to humans

None known.

Giant barred frog

Mixophyes fasciolatus

taxonomy

Mixophyes fasciolatus Günther, 1864, Clarence River, New South Wales, Austalia.

other common names

None known.

physical characteristics

This large frog has a proportionately large head, powerful hind limbs, and moderately webbed toes. The males are 2.4–2.6 in (60–65 mm), and the females are 2.8–4 in (72–101 mm). The dorsum is brown or gray with well-defined blotches on the body, stripes on the head, and transverse bars on the limbs.

distribution

The species occurs along the Great Dividing Range and eastern coast from Bundaberg in Queensland to the southern coast of New South Wales, Australia.

habitat

The frogs inhabit the forest floor adjacent to streams.

behavior

A crepuscular and nocturnal species, little is known of its behavior other than its reproductive strategy.

feeding ecology and diet

The diet consists of insects and smaller frogs.

reproductive biology

Breeding usually takes place along streams but sometimes in unconnected pools near streams and drainages away from streams. Amplectant pairs sit in the water facing the bank. A few eggs are laid and then kicked in a spray of water onto the bank or rock face by the female, where the eggs stick to the surface. Hatching tadpoles fall into the water. The stream-adapted tadpoles have ventral suctorial mouths.

conservation status

Not threatened. The species seems to be secure, which may be because of a broader use of habitat than its congeners.

significance to humans

None known.

Painted frog

Neobatrachus pictus

taxonomy

Neobatrachus pictus Peters, 1863, Loos, 2.8 mi (4.5 km) west of Gawler (Buchsfelde), South Australia.

other common names

English: Trilling frog.

physical characteristics

This moderate-size, rotund frog has short limbs and a short head. The males are 1.8–2.3 in (46–58 mm), and the females are 1.9–2.2 in (48–55 mm). This frog is brightly colored, with yellow, gray, or pale brown markings with irregular dark patches and a warty dorsum. In breeding males, these warts are tipped with spines. The inner metatarsal tubercle is large, compressed, keratinized, and black. The toes are almost fully webbed, and the pupil is vertically elliptical when constricted.

distribution

This species lives in southeastern South Australia and probably in adjoining parts of Victoria and New South Wales, Australia.

habitat

This frog inhabits clay pans, grassy marshes, roadside pools, and open woodland.

behavior

This burrowing species forms a cocoon. Once below the surface of the ground, the outer keratinous layer of skin is lifted from the body, as if to be shed, but remains attached, enclosing the entire animal except for the nostrils, which remain open to the exterior. The cocoon splits and is shed after rain percolates down through the soil to the estivating animal. The frog digs its way to the surface and breeds and feeds before digging down again as drought sets in.

feeding ecology and diet

Nothing is known about the feeding ecology or diet of this species, but it probably feeds on arthropods.

reproductive biology

Many animals emerge from the ground after heavy rains. The call is a musical trill. Small, pigmented eggs are laid as loose clumps in vegetation at the edge of pools. Tadpoles, which have massive jaw sheaths, grow as large as 3.5 in (up to 90 mm) before metamorphosing.

conservation status

Not threatened.

significance to humans

Skin secretions are believed to be harmful if ingested.

Northern spadefoot toad

Notaden melanoscaphus

taxonomy

Notaden melanoscaphus Hosmer, 1962, Borroloola, Northern Territory, Australia.

other common names

French: Pied-en-bêche du nord.

physical characteristics

This moderate-size, rotund species has short limbs and a short snout. The males are 1.3–1.9 in (34–48 mm), and the females are 1.8–1.9 in (45–49 mm). The dorsum is gray or olive brown, with large, dark, symmetrical blotches. The dorsum is warty, and the warts commonly are tipped with white. Juveniles typically have bright yellow, red, and black spots. The inner metatarsal tubercle is black and keratinized.

distribution

The species is widespread in eastern and northern Kimberley, Western Australia, across to Townsville, Queensland, Australia.

habitat

The frog is found in flooded grassland after torrential rains.

behavior

This burrowing species exudes a sticky, yellow-orange, gluelike substance when disturbed; the exudate hardens quickly and is difficult to remove. It does not appear to be toxic to other frogs. These frogs run rather than hop; at night they can be mistaken for small rodents.

feeding ecology and diet

The mouth is small, and, hence, these frogs are restricted in their diet to small arthropods. They flick the tongue rather than bite at prey.

reproductive biology

Males inflate the entire body while lying in shallow water and call, "whoop, whoop, whoop." If disturbed, they deflate, sink, and remain silent until the threat has passed. Males grasp females in inguinal amplexus, and eggs are laid as a surface film that sinks as the larvae hatch. The tadpoles seem to be filter feeders rather than grazers.

conservation status

Not threatened. The species is secure across its range.

significance to humans

None known.

Baw Baw frog

Philoria frosti

taxonomy

Philoria frosti Spencer, 1901, Mount Baw Baw, Victoria, Australia.

other common names

None known.

physical characteristics

Males of this species are 1.7–1.8 in (42–46 mm), and females are 1.9–2.2 in (47–55 mm). This moderate-size frog with an indistinct tympanum has a rather drab, dark brown, warty appearance and well-developed parotoid glands; the ventral surfaces and groin are cream or yellowish.

distribution

This species is found only at elevations above 3,800 ft (1,160m) on Mount Baw Baw, Victoria, Australia.

habitat

This frog inhabits tunnels in sphagnum bogs or lives beneath logs and rocks on the sides of streams.

behavior

A reclusive species.

feeding ecology and diet

Nothing is known about the feeding ecology or diet of this species, but it probably feeds on arthropods.

reproductive biology

Males call in frost hollows. Unpigmented eggs are laid in a foam nest in small, seepage-fed depressions beneath logs or rocks or dense vegetation. The jelly breaks down, and tadpoles lacking mouthparts feed on their yolk supply and develop within the liquefied jelly over a period of five to eight weeks.

conservation status

This species is listed as Critically Endangered, but the cause, other than habitat threat, has not been identified. Population decline seems to be a widespread phenomenon at high elevations, and ultraviolet light, temperature, and prolonged drought cannot be tied directly to the declines.

significance to humans

None known.

Resources

Books

Anstis, M. Tadpoles of South-eastern Australia: A Guide with Keys. Sydney: Reed New Holland, 2002.

Barker, John, Gordon C. Grigg, and Michael J. Tyler. A Field Guide to Australian Frogs. Chipping Norton, Australia: Surrey Beatty, 1995.

Campbell, A., ed. Declines and Disappearances of Australian Frogs. Canberra, Australia: Environment Australia, 1999.

Cogger, H. G. Reptiles and Amphibians of Australia. 6th edition. Sydney: Reed New Holland, 2001.

Cogger, H. G., E. E. Cameron, and H. M. Cogger. Zoological Catalogue of Australia. Vol. 1, Amphibia and Reptilia. Canberra, Australia: Australian Government Publishing Service, 1983.

Littlejohn, M. J., M. Davies, J. D. Roberts, and G. F. Watson. "Family Myobatrachidae." In Fauna of Australia. Vol. 2A, Amphibia and Reptilia, edited by C. J. Glasby, G. J. B. Ross, and P. Beesley. Canberra, Australia: AGPS, 1993.

Malone, B. S. "Mortality during the Early Life History Stages of the Baw Baw Frog, Philoria frosti (Anura: Myobatrachidae)." In Biology of Australasian Frogs and Reptiles, edited by G. Grigg, R. Shine, and H. Ehmann. Chipping Norton, Australia: Surrey Beatty and Sons, 1985.

Periodicals

Davies, M., and G. F. Watson. "Morphology and Reproductive Biology of Limnodynastes salmini, L. convexiusculus and Megistolotis lignarius (Anura: Leptodactylidae: Limnodynastinae)." Transactions of the Royal Society of South Australia 118, no. 3 (1994): 149–169.

Katsikaros, K., and R. Shine. "Sexual Dimorphism in the Tusked Frog, Adelotus brevis (Anura: Myobatrachidae): The Roles of Natural and Sexual Selection." Biological Journal of the Linnean Society 60, no. 1 (1997): 39–51.

Parker, H. W. "The Australasian Frogs of the Family Leptodactylidae." Novitates Zoologicae 42, no. 1 (1940): 1–106.

Schauble, C. S., C. Moritz, and R. W. Slade. "A Molecular Phylogeny for the Frog Genus Limnodynastes (Anura: Myobatrachidae)." Molecular Phylogenetics and Evolution 16, no. 3 (2000): 379–391.

Tyler, M. J. "Limnodynastes Fitzinger (Anura: Leptodactlidae) from the Cainozoic of Queensland." Memoirs of the Queensland Museum 28, no. 2 (1990): 779–784.

——. "Kyarranus Moore (Anura: Leptodactylidae) from the Tertiary of Queensland." Proceedings of the Royal Society of Victoria 103, no. 1 (1991): 47–51.

Tyler, M. J., and H. Godthelp. "A New Species of Lechriodus Boulenger (Anura: Leptodactylidae) from the Early Eocene of Queensland." Transactions of the Royal Society of South Australia 117, no. 4 (1993): 187–189.

Tyler, M. J., H. Godthelp, and M. Archer. "Frogs from a Plio-Pleistocene Site at Floraville Station, Northwest Queensland." Records of the South Australian Museum 27, no. 2 (1994): 169–173.

Tyler, M. J., A. A. Martin, and M. Davies. "Biology and Systematics of a New Limnodynastine Genus (Anura: Leptodactylidae) from Northwestern Australia." Australian Journal of Zoology 27, no. 1 (1979): 135–150.