Reproductive Biology ofSceloporus consobrinus(Phrynosomatidae): Male Germ Cell Development and Reproductive Cycle Comparisons within Spiny Lizards

Seasonal spermatogenesis in the Mexican endemic oviparous lizard,Sceloporus aeneus(Squamata: Phrynosomatidae)

“…3 The spermatogenic activity of S. aeneus with peaks of spermiogenesis and spermiation occurring during late winter and spring (i. e., highest sperm abundance in epididymis during March-May), is similar to that found in other oviparous species of Sceloporus. 2,3,24,25 According to the classification scheme provided by Rheubert et al 3 this population of S. aeneus represents a fall recrudescence pattern, which is common in oviparous lizards in temperate habitats. Although this population occurs at a tropical latitude it is located at high elevation where climatic patterns are similar to those found at temperate latitudes.…”

“…However, although no statistical analyses were performed, February showed intermediate quantity of spermatozoa in the epididymis with respect to the massive spermatozoa release recorded during maximum testicular activity (March-May). The present data, along with numerous other studies, [1][2][3][4] suggest that histological data is the most accurate technique compared to size of testis (volume or mass) alone in determining the seasonality of male reproductive/germ cell activity and length of different phases of the spermatogenesis. Therefore, studies involving exclusively macroscopic data to evaluate the male reproductive cycle should be interpreted with caution.…”

“…[1][2][3]11,20 We agree with the efforts in using multiple indicators to describe the spermatogenic cycle of lizards, especially designs that include histological examination of reproductive organs. [1][2][3][4][5][6][7][8][9][10][11][20][21] However, the use of a single indicator may be misleading. For example, some of the data collected for S. aeneus (testis mass) suggest that February should be included in the months classified as maximum testicular activity (Table 1).…”

“…These characterizations are made by the use of histological examinations, which strongly support the various spermatogenic stages in contrast to other types of evidence, such as testicular size (i.e., volume or mass) and/or opaqueness of the extratesticular ducts. [1][2][3][4] Although both seasonal and continuous spermatogenesis have been observed in lizards, seasonal spermatogenesis is by far the most common type of male germ cell cycle. This pattern has been recorded in different genera within Phrynosomatid lizards including: Phrynosoma, 5 Uma, 6 Cophosaurus, 7 Uta, 8 Petrosaurus, 9 Urosaurus, 10 and Sceloporus.…”

“…Previous studies have shown that oviparous species exhibit either seasonal 2,3 or continuous spermatogenesis, 13 and those from high-elevation show a maximum testicular activity during spring. 2,3 Both lizards S. aeneus (oviparous) and S. bicanthalis (viviparous) belong to the scalaris group, being considered as sister taxa. [14][15][16][17] Although both of them are endemic to central M exico, their distribution is distinctive as S. bicanthalis takes the place of S. aeneus at elevations above 3000 m. 16 S. bicanthalis was once considered a subspecies of S. aeneus but has now been elevated to the species level.…”