Cnemidophorus tigris marmoratus

TAYLOR, HARRY L., COLE, CHARLES J., HARDY, LAURENCE M., DESSAUER, HERBERT C., TOWNSEND, CAROL R., WALKER, JAMES M. & CORDES, JAMES E., 2001, Natural Hybridization Between the Teiid Lizards Cnemidophorus tesselatus (Parthenogenetic) and C. tigris marmoratus (Bisexual): Assessment of Evolutionary Alternatives, American Museum Novitates 3345, pp. 1-1 : 1-

Cnemidophorus tigris marmoratus Males

AMNH R­146650 (June 11, 1998): The left testis was 3.7 X 2.9 mm. The seminiferous tubules contained sperm and spermatids ( fig. 19D ), and meiotic divisions were visible. A thick tunica vasculosa and thinner tunica albuginea were present. The Leydig cell layer was thin .

AMNH R­146652 (June 13, 1998): The left testis was 2.6 X 1.9 mm. The seminiferous tubules had poorly developed lumina that contained large spermatogonia­like cells with darkly stained nuclei ( fig. 19E ). The tubule walls also contained large vacuolated cells; spermatocytes were present but no sperm were visible ( fig. 19F ). The thin wall contained smooth muscle. The large lumen

of the vas deferens contained irregular cells, almost like debris; no sperm were present. The tunica albuginea and tunica vasculosa were as described by Goldberg and Lowe (1966). The Leydig cell layer of the tunica vasculosa was thin and incomplete. The seminiferous tubules were occluded with fibrous material and some spermatids, and only a few spermatogonia and primary spermatocytes were present. Since the specimen (snout–vent length = 65 mm) was at the minimum size for sexual maturity (snout– vent length = 64 mm; Vitt and Breitenbach, 1993), it is likely that limited spermatogenesis had begun, but that sperm were not yet being moved from the seminiferous tubules to the epididymis. Sertoli cells were not obvious ( fig. 19E, F ). The mesonephric tubules were of normal (20–30 µm) or large (75–100 µm) size.

AMNH R­146653 (June 13, 1998): The left testis was 5.4 X 3.3 mm. Most of the seminiferous tubules were almost empty but all contained a few sperm; however, masses of sperm were present in a few tubules in the center of the testis and also in the vas deferens and epididymis ( fig. 18H ). Those tubules without masses of sperm were occluded with fibrous material and a few spermatids as in AMNH R­146652. Reproductive activity was probably ending because the seminiferous tubules had a poorly defined lumen, occluded with nonreproductive material, and spermatids were less abundant. Since the epididymis contained sperm ( fig. 18H ), a recent copulation probably had not occurred, if empty vasa deferentia are true indicators of copulation (Goldberg and Lowe, 1966).

Of the three male C. tigris marmoratus examined, one small individual of 65 mm snout–vent length ( AMNH R­146652) appeared to be in the process of acquiring re­ productive maturity, and the other two (each 92 mm snout–vent length) were reproduc­

tively competent.

Cnemidophorus tesselatus X C. tigris mar­

Figures

Fig. 19. Testes of hybrid males (A–C, G, H) and C. tigris males (D–F). Note that G and H are out of sequence because of size. A. Testis with sperm (AMNH R­145145, slide 5, row 2, section 3). B. Testis with debris and few sperm (AMNH R­146683, slide 10, row 1, section 4). C. Seminiferous tubules

Fig. 18. Mesonephros of hybrid females (A, B), C. tesselatus (C, D), hybrid males (E–G), and a C. tigris male (H). A. Mesonephros showing small and large tubules (AMNH R­145147, slide 8, row 2, section 6). B. Adrenal gland with large and small mesonephric tubules (AMNH R­145146, slide 11, row 1, section 2). C. Ovary and adrenal with small mesonephric tubules; no large tubules present (AMNH R­146640, slide 4, row 1, section 1). D. Mesonephros with small tubules; no large tubules present (AMNH R­146629, slide 10, row 1, section 4). E. Large tubules (= epididymis) and small mesonephric tubules; debris does not include sperm (AMNH R­145148, slide 8, row 1, section 6). F. Epididymis and small mesonephric tubules (AMNH R­146695, slide 25, row 3, section 6). G. Vas deferens and small mesonephric tubules (AMNH R­146692, slide 12, row 2, section 6, MT). H. Large mesonephric tubules and epididymis (packed with sperm) and small mesonephric tubules (AMNH R­ 146653, slide 10, row 2, section 4). Scale bar, 0.1 mm, except G, which is 0.01 mm.