REPRODUCTION AND SEXUAL DIMORPHISM IN TWO POPULATIONS OF SCELOPORUS GRAMMICUS (SAURIA: PHRYNOSOMATIDAE) FROM HIDALGO, MEXICO

We studied the reproductive cycle of Sceloporus grammicus from two localities in Hidalgo, Mexico: La Estanznela (LE) and Tilcuautla (TIL) of the Municipality of Mineral del Chico and San Agustin Tlaxiaca, respectively. Males were larger than females in both populations, with males having larger snoutvent lengths (SVLs), heads, and limbs than females. Males from LE reached sexual maturity at a larger SVL (42.2 mm) than males from TIL (38.9 mm). Females from LE reached sexual maturity at a smaller SVL (41.6 mm) than females from TIL (44.6 mm). Reproductive activity of both sexes from both populations was asynchronous. Testicular recrudescence at LE occurred May-July, reaching maximum activity August-October, and showing regression November-December, whereas in TIL, recrudescence occurred May-June, reaching maximum activity July-October, and showing regression November-December. Vitellogenesis occurred May-October in both populations, with ovulation occurring November-December. Embryonic development was observed November-March in both populations. Hatchlings from LE and TIL first appeared in March. Mean litter size for both populations was similar (LE, 4.75; TIL, 4.66) and increased with female SVL. Reproduction of S. grammicus for both populations was different from other montane populations but similar to populations from low elevations.