Age structure and growth features of the Tajikistan toadhead agama Phrynocephalus sogdianus (Reptilia, Agamidae)

The paper presents the results of age and growth studying of the Tajikistan toadhead agama Phrynocephalus sogdianus by skeletochronology. A total of 29 adult individuals (14 females and 15 males) from the vicinity of Uchkyzil (Termez district, Surkhandarya region, Uzbekistan) were studied. All animals, on the section of tubular bones had a birth (hatching) line appearing shortly after the lizards hatching. The majority of the sample consisted of one-year-old and two-year-old specimens (89.7%). The age of females and males varied between 1–3 years, averaging 1.53 and 1.71 years, respectively. The expected calculated life expectancy for females after one wintering was 2.25 years, for males 2.06 years. Females and males did not differ in body length. The length of the males’ body depended on their age. Males aged one and two years statistically significantly differed in size among themselves. The authors note that P. sogdianus has very high growth rates (growth coefficient k is 2.84 in females and 1.40 in males), exceeding that of other toadhead agamas.