Species account

Description
Small colourful newt. Head flattened, longer than wide. Snout rounded. Paratoids not prominent. Trunk almost round, rather slender, without dorsal ridge, but with slight vertebral depression. Tail almost as long as snout-vent length, rounded at the base, compressed laterally toward the tip. Skin of dorsal side rather smooth with small warts. Ventral side smooth.

Colour black with irregular-shaped white blotches covering head, back and sides of body and tail. White blotches sometimes forming white bands on the sides. Yellow-orange stripe along the back, bordered with irregular white spots, forming a wave pattern. Sometimes orange spots on white patches in paratoid region. Limbs white or orange with black patches. Ventral surface of head, body, limbs and tail orange.

Male cloaca swollen in the breeding season. Female cloaca extended in tubular shape 5-6 mm, much longer than in other Neurergus species (Schmidtler & Schmidtler, 1975). Apart from the form of the cloaca in the breeding season no sexual dimorphism.

Total length between 11 and 14 cm (Schmidtler & Schmidtler, 1975).

Diagnosis
Small newt with spectacular black, white and orange coloration. Yellow-orange stripe on the back and uniformly orange on ventral side. Female with strongly extended cloaca in breeding season.

Eggs and larvae
Oviposition takes place in March-April, depending on altitude. Eggs are pressed singly in small cracks and crevices in rocks. Jelly capsule 4 mm in diameter, the embryo diameter is 1.5-2 mm (Schmidtler & Schmidtler, 1975). Larvae hatch after approx. 17 days at a length of 13-14 mm (Steinfartz & Schultschik, 1997; Schultschik, 2007). Young larvae were found at the type locality in mid-April. End May Schmidtler & Schmidtler (1975) found larvae nearing metamorphosis in a water body with water temp. exceeding 20ºC. High temperatures lead to rapid metamorphosis. In captive animals metamorphosis takes place after three and a half months at a length of 45-55 mm (Schultschik, 2007).

The dorsal tail-fin of the larva reaches well over the middle of the body, which is a characteristic of pond-type larvae. Younger larvae are yellow with minute black dots. Older larvae have light spots along the back, often forming median rows. Belly uniformly light-coloured. Tail almost invariably without dark pigment. For comparative larval morphology of Neurergus, see Schmidtler & Schmidtler (1975).

Distribution
Neurergus kaiseri is only known from two spring-fed streams, Shahbazan and Talehzang, in the southern Zagros range in Iran. A third population has disappeared. (Rastegar-Pouyani et al., 2005; IUCN, Conservation International & NatureServe, 2006).

Habitat
Spring-fed streams at 500 to 1,430 m altitude. The streams are mostly surrounded by arid scrubland (Schultschik & Steinfartz, 1996; IUCN, Conservation International & NatureServe, 2006).

Behaviour
Activity probably starts in December-January, when rain is falling (Schultschik, 2007). Adult animals disappear from the streams after reproduction in March-April when the temperature rises and water dries up; at higher altitudes with cooler climatic conditions the reproductive cycle starts and ends later. It is unclear where the animals spend the summer and winter months (Schmidtler & Schmidtler, 1975).

Reproductive behaviour was studied in captive specimens of N. kaiseri, originating from Shahbazan, Iran. The male takes up a position in front of the female, from where he starts a tail-fanning display, fanning his tail in the direction of her snout. If the female is responsive and approaches the male, he turns away and creeps ahead of her, his tail making undulating movements. The female follows him, touching his tail. The male deposits a spermatophore, moves forward and makes a 90º turn, bringing him back into a position perpendicular to the female’s body. He stops (brakes) the female in her progress at a point when her cloaca is situated above the place where the spermatophore was deposited. This behaviour was found to be similar in N. strauchii, N. crocatus and N. kaiseri. For N. microspilotus observations are uncertain. In its general pattern, this courtship behaviour is similar to that of small European pond breeding newts and of Asian Cynops, Pachytriton and Paramesotriton (Sparreboom et al., 2000).

Threats and conservation
Habitat loss as a result of wood extraction for small-scale subsistence use, coupled with the effects of severe droughts, are the major threats to the species (IUCN, Conservation International & NatureServe, 2006). Given the rarity of the species, collection for the pet trade could in principle be a serious threat.  

Observations in captivity
Neurergus kaiseri has been bred in captivity on several occasions (Steinfartz & Schultschik, 1997; Schultschik, 2007) but it is sensitive, and rearing the juveniles has proved difficult. This species requires higher water temperatures than other Neurergus species. At temperatures below 18ºC the newts stop feeding and remain in their hiding places. Temperatures around 24ºC elicit oviposition. The newts are strictly nocturnal and shy away from light. Throughout the year, the newts partly live in water, partly on land (Schultschik, 2007). The data on courtship, oviposition and larval development reported above have been obtained from captive animals.

Comments
An enigmatic species, much of whose natural history is still unknown. Neurergus kaiseri larvae, with their long and relatively high tail-fin, seem to be more adapted to still water than the larvae of the other, stream-dwelling, Neurergus species. Eggs are smaller than in the other species, which may also indicate pond-breeding habits. For this reason N. kaiseri has been termed a pond-breeder (Steinfartz et al., 2002), but observations in the natural habitat are lacking. The elongated form of the female cloaca most likely is an adaptation to egg-laying in running water, similar to Euproctus platycephalus and Paramesotriton caudopunctatus. The terrestrial habitat is extremely hot and dry, which leads to the theory that the species may mainly live and reproduce in underground waters and come into the open only on rare occasions (Schultschik, 2007).

Neurergus kaiseri
© Sergé Bogaerts

 
© 2004 IUCN, Conservation International and NatureServe. (click on map to enlarge)