This family includes the largest living salamanders. longitudinal skin folds on fl anks. There are two genera Cryptobranchid salamanders are specialised for an in this family, Cryptobranchus, the Hellbender, in aquatic habitat comprising cold, fast-fl owing, rocky, eastern North America, and Andrias in China and and oxygen rich streams. They are generally found Japan. There are two extant species of Andrias, one living in depressions under stones in streams and occurring in central China, the other in Japan. rivers. Females lay long, paired strings of several hundred eggs, which are fertilised externally by the In the fossil record, cryptobranchids are well represent- male. Males guard the eggs until they hatch 2-3 months ed in the Cenozoic of Eurasia (Vasilyan et al., 2013). after laying. Metamorphosis is partial and the animals Fossils of Andrias are known from the Tertiary of are permanently aquatic. Adults have a number of Europe and western North America. For detailed paedomorphic characters: they have small eyes, lack characteristics of the Cryptobranchidae, see Thorn eyelids and have one pair of gill slits. The gill slits (1969), Estes (1981), Duellman & Trueb (1986), Larson remain open in the American species (Cryptobranchus), et al. (2003), and Browne et al. (2012). but are closed in the Asiatic species (Andrias). Lacrimals and septomaxillae are absent. The palatal teeth form References Browne et al. (2012), Duellman & Trueb (1986), a curved row parallel to the maxillary and premaxillary Estes (1981), Larson et al. (2003), Thorn (1969), Vasilyan teeth. Head large and broad. Head and body fl attened; et al. (2013).

Cryptobranchidae Fitzinger, 1826

Chinese Giant Salamander, Andrias davidianus, Xiao Yu Dong (Small Fish Cave), Daba, Wenxian County, Sichuan. Photo: Ted Papenfuss.

26 Salamanders of the Old World | Cryptobranchidae Andrias Tschudi, 1837

The cryptobranchid genus Andrias contains the largest living The genus includes two closely related forms, which likely salamander species, with adults reaching a total length of diverged in the Pliocene (about 4.3 MYA). Despite a small more than 100 cm. Vomerine teeth located on anterior margin degree of genetic differentiation, they are considered separate of vomer, parallel with maxillary tooth row; teeth form a long species (Matsui et al., 2008a). arc. Nasals in contact with maxilla; frontal does not enter external naris. Pteroid broad, almost in contact with base of Andrias davidianus (Blanchard, 1871) maxilla. Hyoid arches cartilaginous. Two pairs of branchial Andrias japonicus (Temminck, 1836) arches. Body large, no spiracle on head. Distance between nostrils less than half the distance between the eyes. Tongue References Matsui et al. (2008), Zhao & Hu (1988a). large. Tubercles on highly vascular skin (Zhao & Hu, 1988a).

Andrias davidianus (Blanchard, 1871) | Chinese Giant Salamander

Description Andrias davidianus is a very large, heavily built Diagnosis The Chinese Giant Salamander is very similar to salamander. Head strongly depressed, snout obtusely truncate; the Japanese Giant Salamander (Andrias japonicus) and differs nostrils small, rounded, close to the edge of the upper lip and from it in the arrangement of tubercles on the head and throat. at the corners of the truncated snout, the internasal space less The tubercles of A. davidianus are mostly in pairs, and much than half that of the interorbital space. Eyes small, rounded, smaller and fewer than those of A. japonicus. The tubercles on dorso­lateral in position, and without eyelid. Top of head more the throat are characteristic for each species. In A. davidianus, or less fl at, with a rounded temporal protuberance above and these tubercles are very small and paired and are arranged in behind each eye. Vomerine teeth in an arched series starting rows parallel to the lower jaw. In A. japonicus they are mostly between the choanae, parallel to the maxillary and premax­ large, single and irregularly scattered. The snout is less rounded illary series. A thin lower labial fold, starting about midway and the tail a little longer in the Chinese species, which is also between nostril and eye to the angle of the mouth. Trunk less darker in colour with large black patches (Chang, 1936; Liu, 1950; depressed than head, with 12­15 costal grooves, a strong verte­ Thorn, 1969). bral groove, and strong lateral dermal folds. Legs short and sturdy with skin folds. Tail compressed. Tail length 59­80% There is substantial genetic variability, but variations correlate of the snout­vent length (Liu, 1950). Dorsal tail­fi n extending poorly with geographical distribution over the three major to the trunk. Skin slippery and porous, with wrinkles, folds river systems in which it occurs (Murphy et al., 2000, but see and tubercles. Tao et al., 2005). The genetic patterns discovered in these studies suggest a much higher gene fl ow between populations Great variation in colour. Most specimens are dark brown, but of A. davidianus than in A. japonicus (Browne et al., 2012). individuals can be black, dark red, light brown or earth­toned. There are large irregular dark blotches on dorsal and ventral Eggs and larvae Clutch size depends on body weight sides. Juveniles often have lighter colouration with small black of the female. A female of 0.5­3 kg can lay 300­600 eggs or more. spots. Albinos have been reported (Fei et al., 2006). Eggs are laid in a string in an underwater cavity occupied by a male, and are fertilised externally and guarded by the male No external sexual dimorphism. During the breeding season, until they hatch. Egg diameter is 5­8 mm and capsule diameter cloacal lips are swollen in the male and fl at in the female. is 15­17 mm. Incubation takes 38­40 days at water temperatures of 14­21°C. Hatchlings measure 25­32.5 mm. External gills Total length ca. 100 cm. Chang (1936) quotes a maximum of disappear when total length reaches 170­220 mm (Fei et al., 180 cm, but most animals found nowadays are considerably 2006). Haker (1997) reports that eggs measured on average smaller (Liu & Liu, 1998). Fei et al. (2006) give sizes of 760­900 22×19.2 mm and the diameter of the embryo was 8­9 mm. mm for adult males and 470­875 mm for females (from Songtao, Reduction of gills began when the larvae were 200­250 mm Guiding, Jiangkou, Leishan, Guizhou). Specimens of 115 cm total length (Haker, 1997). The larvae resemble the adult weigh ca. 25 pounds (11.4 kg, Liu, 1950). in shape.

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