Keywords: Serpentes, Colubridae, Rhadinea decorata, reproduction, Costa Rica.
The Adorned Graceful Brown Snake Rhadinea decorata (Colubridae) is known from humid broadleaf evergreen forests from southern Mexico to Ecuador; it is active in the daytime and eats mainly Eleutherodactylus frogs and their terrestrial eggs (Savage 2002). Solórzano (2004) reported R. decorata clutch sizes of up to four eggs. The purpose of this paper is to present new information on the reproductive cycle of R. decorata from Costa Rica based on a histological examination of gonadal material from museum specimens. The first information on the timing of the testicular cycle is also presented. Comparisons are made with the timing of testicular cycles of other snakes from Costa Rica as part of an ongoing series of studies on the reproductive biology of snakes from this area.
A sample of 22 specimens of R. decorata from Costa Rica (collected 1959-1985) was examined from the herpetology collection of the Natural History Museum of Los Angeles County (LACM) Los Angeles, California, USA (Appendix I). Counts were made of enlarged ovarian follicles (> 8 mm length) or oviductal eggs. The left testis and vas deferens were removed from males and the left ovary was removed from females for histological examination. Tissues were embedded in paraffin, sectioned at 5 µm and stained with hematoxylin followed by eosin counterstain. Testis slides were examined to determine the stage of the testicular cycle and ovary slides were examined for the presence of yolk deposition (secondary vitellogenesis sensu Aldridge 1979). Follicles in advanced stages of yolk deposition or oviductal eggs were not examined histologically. An unpaired t test was used to compare male and female mean body sizes (SVL) (Instat vers. 3.0b, Graphpad Software, San Diego, CA).
Seven females (mean snout-vent length [SVL] = 229 mm ± 23 SD, range: 208-250 mm); 13 males (SVL = 190 mm ± 29 SD, range: 172207 mm) and 2 neonates SVL 90 and 98 mm were examined.
All testes examined exhibited spermiogenesis with metamorphosing spermatids and sperm present. Vasa deferentia also contained sperm. The following monthly numbers of R. decorata males were undergoing spermiogenesis: February (1), March (3), May (2), July (2), August (2), September (2), October (1). The smallest spermiogenic male measured 120 mm SVL (LACM 131127).
I thank Christine Thacker (LACM) for permission to examine specimens. Jessica Carlson assisted with histology. Snakes are part of the CRE collection donated to LACM by Jay Savage in 1998.
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Appendix I – Specimens Examined
COSTA RICA – Alajuela, 131127; Cartago 154326, 154329, 154334; Limón 154311, 154316; Heredia 154306, 154307, 154313, 154312, 154323, 154333; Puntarenas 154308, 154315, 154317, 154320, 154322, 154324, 154310, 154314, 154319, 154321.
Republished under an open access licence.
Phyllomedusa 6(2):151-153, 2007
© 2007 Departamento de Ciências Biológicas - ESALQ - USP