Key to Identification of Amphibians

AMPHIBIA  [CPIE Amphibians List]  No native amphibians are known from Hawaii, no doubt because these vertebrates are strictly terrestrial and freshwater inhabitants and the Islands are isolated by the vast Pacific Ocean from continental environments where amphibians are native. Four or five species of frogs and one toad have been introduced (McKeown, 1996) and may be observed around streams and ponds, although strictly speaking only four of these species breed in these habitats and only two or three inhabit them as adults. Upon hatching from a soft egg laid in water or other moist environment, both toads and frogs reside in water as tadpoles, breathing with gills, eventually growing to metamorphose into juveniles looking like small versions of the adult. This key attempts to cover eggs, tadpoles, and adults. In the key sizes of adults are given in centimeters as the snout to vent length (body length). Tadpoles with developed hind legs have probably reached maximum size and will decrease somewhat in length as the tail is resorbed.

	31a		Amphibian eggs. Dark, rounded bodies (1 mm or larger) enmeshed in a clear gel	[40]
	31b		Amphibian tadpole. Legs lacking, or only hind legs developed	[37]
	31c		Amphibian juvenile or adult. Four legs present; hind legs stronger than fore-legs and adapted for swimming and/or leaping. Tail usually lacking	[32]
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	32a	(29) & (31)	Prominent swellings on side of head behind each eye comprising parotoid glands which produces a white, toxic secretion when the animal is handled. Body stocky, front (nose and mouth) rather blunt and short (eyes set forward). Skin warty all over. Color of back varies from mottled tan, black, and white to a more even brown on large individuals. To 18 cm. Giant neotropical toad ~ Family BUFONIDAE Bufo marinus	[Note B]
	32b		Without parotoid glands. Front angular, produced forward from eyes. Skin relatively smooth all over or roughened by either circular or linear warts on dorsal surfaces only	[33]
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	33a	(31)	Tips of toes expanded (toe pads present)	[34]
	33b		Toes not expanded at tips. True frogs ~ Family Ranidae	[35]
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	34a	(33)	Skin smooth, strikingly colored in black (or dark brown) and green (or white) spots and bars. Small frogs (to 4 cm.) living in wet forests of the Ko`olau (O`ahu). Dart-poison frog ~ Family DENDROBATIDAE Dendrobates auratus	[Note B]
	34b		Skin with scattered, circular warts; color variable, but typically a brown to olive-green, not strikingly patterned. To 10 cm. Living in wet forests of the Ko`olu (O`ahu). Cuban tree frog ~ Family HYLIDAE Osteopilus septentrionalis	[Note B, Note C]
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	35a	(33)	Dorso-lateral skin fold (a ridge along upper side of body) extending back from eye nearly to hind leg; otherwise similar to Rana catesbeiana (see below) but of smaller maximum size (under 10 cm). Juveniles may be profusely dark-spotted on back. Green frog Rana clamitans	[Note A]
	35b		Dorso-lateral skin fold absent or extending downward behind eardrum (tympanum)	[36]
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	36a	(35)	Upper surface of body smooth; color mostly olive, green, or brown above, with some large spots on legs and maybe back; green around upper lip. When startled, gives a cat-like alarm cry upon leaping into water. Usually large size (to 20 cm). Freshwater ponds, lakes, and marshes. American Bullfrog Rana catesbeiana Shaw
	36b		Upper surfaces of body and legs with rows of linear warts or ridges; color an even gray, brown, or olive with black speckles. Usually small size (to 4.5 cm). Freshwater pools and streams at higher elevations on most Islands. Wrinkled frog Rana rugosa
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	37a	(35) & (26)	Tadpole dark (usually an even black) and usually small (under 2 cm)	[38]
	37b		Tadpole some shade of olive-green with extensive speckling or mottling of white and/or black; usually larger than 2 cm	[39]
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	38a	(37)	Oral papillae confined to sides of mouth, which is indented. Small (under 2.5 cm), very dark to black in color. Common and usually present in large numbers in pools, ponds, or quiet waters of streams ~ Family BUFONIDAE Bufo marinus
	38b		Oral papillae on sides and lower lip; mouth indented or not. Found in small numbers, varying in size up to 45 cm, in isolated pools or other standing water in wet forests on O`ahu (Ko`olau) ~ Family DENDROBATIDAE Dendrobates auratus ~ Family HYLIDAE Osteopilus septentrionalis	[Note A]
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	Rana catesbeiana tadpoles
	39a	(37)	Tadpole extensively mottled in white with black speckles, to 12 cm in length. American bullfrog (photos above) Rana catesbeiana Shaw
	39b		Tadpole mottled gray-green to brown and maybe with white speckles, but with few or no black speckles. Usually under 5 cm total length. Mountain streams and pools. Wrinkled frog Rana rugosa
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	40a	(7) & (31)	Spherical ova (eggs) or elongated embryos pigmented on upper surface and arranged within a long, cylindrical (string like), gelatinous sheath. Giant neotropical toad. Common in standing water ~ Family BUFONIDAE Bufo marinus
	40b		Eggs or embryos single, OR in irregular clusters, OR within a floating, gelatinous mass	[41]
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	41a	(40)	Eggs or embryos in a floating, gelatinous raft	[42]
	41b		Eggs or embryos in an irregular cluster ?Rana rugosa ?Osteopilus septentrionalis	[Note A]
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	42a	(41)	Ovum with 1 envelope { in a floating cluster to 1.5 m across. American bullfrog Rana catesbeiana Shaw
	42b		Ovum with 2 envelopes { in a floating cluster under 30 cm across. Green frog Rana clamitans	[Note A]

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Note A:

Although your identification may be correct, the species you arrived at is either rare or of limited or uncertain distribution in Hawai`i. Carefully compare the description with your specimen or observation and reconsider choices made in last few couplets to insure that a rare species is not being mistaken for a common species.

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Note B:

A terrestrial species not generally found in streams or ponds as adults, but may visit these, or other standing water.

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Note C:

An introduced pest species of particular concern. Specimens should be euthanized, preserved for study, or turned over to the State of Hawaii, Department of Agriculture. Report sightings and DO NOT RELEASE into the wild.