Goldberg, Stephen R.

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Phyllomedusa - 6(2), December 2007151Notes on reproduction of the adorned gracefulbrown snake, Rhadinea decorata (Serpentes,Colubridae), from Costa RicaStephen R. GoldbergDepartment of Biology, Whittier College, Whittier, California 90608, USA. E-mail: sgoldberg@whittier.edu.Received 24 April 2007.Accepted 8 August 2007.Distributed December 2007.Phyllomedusa 6(2):151-153, 2007© 2007 Departamento de Ciências Biológicas - ESALQ - USPISSN 1519-1397Keywords: Serpentes, Colubridae, Rhadinea decorata, reproduction, Costa Rica.The Adorned Graceful Brown SnakeRhadinea decorata (Colubridae) is known fromhumid broadleaf evergreen forests from southernMexico to Ecuador; it is active in the daytimeand eats mainly Eleutherodactylus frogs andtheir terrestrial eggs (Savage 2002). Solórzano(2004) reported R. decorata clutch sizes of up tofour eggs. The purpose of this paper is topresent new information on the reproductivecycle of R. decorata from Costa Rica based on ahistological examination of gonadal materialfrom museum specimens. The first informationon the timing of the testicular cycle is alsopresented. Comparisons are made with thetiming of testicular cycles of other snakes fromCosta Rica as part of an ongoing series ofstudies on the reproductive biology of snakesfrom this area.A sample of 22 specimens of R. decoratafrom Costa Rica (collected 1959-1985) wasexamined from the herpetology collection of theNatural History Museum of Los Angeles County(LACM) Los Angeles, California, USA(Appendix I). Counts were made of enlargedovarian follicles (> 8 mm length) or oviductaleggs. The left testis and vas deferens wereremoved from males and the left ovary wasremoved from females for histologicalexamination. Tissues were embedded inparaffin, sectioned at 5 µm and stained withhematoxylin followed by eosin counterstain.Testis slides were examined to determine thestage of the testicular cycle and ovary slideswere examined for the presence of yolkdeposition (secondary vitellogenesis sensuAldridge 1979). Follicles in advanced stages ofyolk deposition or oviductal eggs were notexamined histologically. An unpaired t test wasused to compare male and female mean bodysizes (SVL) (Instat vers. 3.0b, GraphpadSoftware, 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: 172-207 mm) and 2 neonates SVL 90 and 98 mmwere examined.All testes examined exhibited spermio-genesis with metamorphosing spermatids andsperm present. Vasa deferentia also containedsperm. The following monthly numbers of R.decorata males were undergoing spermio-genesis: February (1), March (3), May (2), July(2), August (2), September (2), October (1). Thesmallest spermiogenic male measured 120 mmSVL (LACM 131127).Phyllomedusa - 6(2), December 2007152Females were larger than males (unpaired t-test, 18 df, t = 3.07, P = 0.007). Three femaleswith oviductal eggs were observed, one (1 egg)collected in January (LACM 154320), one (2eggs) collected 19 July-2 August (LACM154313) and one (3 eggs) collected in August(LACM 154317). The smallest reproductivelyactive R. decorata female (1 oviductal egg)measured 203 mm SVL (LACM 154320). Threefemales were undergoing yolk deposition =secondary vitellogenesis; one each from July,August and December. One female (SVL = 202mm) from February was reproductively inactive(no yolk deposition). Most of the females(86.7%) were reproductively active. There wasno evidence that R. decorata from Costa Ricaproduce more than one clutch of eggs per year(oviductal eggs and yolk deposition in the samefemale) although the existence of reproductivelyactive females in different parts of the year:January, July, August, December suggests thatthis might be possible. Solórzano (2004)previously reported clutches of up to four eggsfor R. decorata but did not give a mean clutchsize.Two (presumably) neonates of R. decoratawere collected, one each in September andNovember.Results obtained in the present study suggestthat R. decorata males produce spermthroughout the year. Extended testicular cycleshave also been reported in other snakes fromCosta Rica: Drymobius margaritiferus(Goldberg 2003a), Dendrophidion sp.(Goldberg 2003b), Ninia maculata (Goldberg2004a), Erythrolamprus bizona and E. mimus(Goldberg 2004b), Micrurus nigrocinctus(Goldberg 2004c), Hydromorphus concolor(Goldberg 2006a), Mastigodryas melanolomus(Goldberg 2006b), and Geophis godmani(Goldberg 2007). Whether this is typical ofsnakes from Costa Rica must await histologicalexamination of testes from additional species ofCosta Rican snakes.The preceding observations on thereproductive cycle of males and femalesindicates that R. decorata has a prolongedreproductive cycle in Costa Rica in which bothsexes are in reproductive condition, at least,through most of the year. This fits into the“polyestrous with continuous reproduction” ofSaint Girons (1982). Fitch (1982) reported year-round breeding in snakes from some aseasonalequatorial regions. Zug et al. (1979) reportedcontinuous or aseasonal reproduction for thecolubrid snakes, Dipsas catesbyi in Peru andImantodes cenchoa from Peru/Ecuador. Incontrast the congener Rhadinea flavilata whichoccurs in the southeastern United States followsa seasonal reproductive cycle in which breedingoccurs in the spring and eggs are laid from lateMay to mid-August (Ernst and Ernst 2004). Thetiming of this reproductive cycle is similar tothose of other colubrid snakes from northtemperate areas of North America (e.g.,Goldberg and Parker 1975) and fits into the“aestival spermatogenesis” of Saint Girons(1982). Subsequent investigations are needed toascertain how widespread extended reproductivecycles are in the snakes of Costa Rica.AcknowledgementsI thank Christine Thacker (LACM) forpermission to examine specimens. JessicaCarlson assisted with histology. Snakes are partof the CRE collection donated to LACM by JaySavage in 1998.ReferencesAldridge, R. D. 1979. Female reproductive cycles of thesnakes Arizona elegans and Crotalus viridis.Herpetologica 35: 256–261.Ernst, C. H. and C. H. Ernst. 2003. Snakes of the UnitedStates and Canada. Washington. Smithsonian Books.668 pp.Fitch, H. S. 1982. Reproductive cycles in tropical reptiles.Occasional Papers of the Museum of Natural Historyof the University of Kansas 96: 1–53.Goldberg, S. R. 2003a. Reproduction in the speckled racer,Drymobius margaritiferus (Serpentes: Colubridae),from Mexico and Central America. Texas Journal ofScience 55: 195–200.GoldbergPhyllomedusa - 6(2), December 2007153Goldberg, S. R. 2003b. Reproduction in four species ofDendrophidion from Costa Rica (Serpentes: Colu-bridae). Transactions of the Illinois State Academy ofScience 96: 295–300.Goldberg, S. R. 2004a. Reproduction in the coffee snake,Ninia maculata (Serpentes: Colubridae), from CostaRica. Texas Journal of Science 56: 81–84.Goldberg, S. R. 2004b. Notes on reproduction in the falsecoral snakes, Erythrolamprus bizona and Erythro-lamprus mimus (Serpentes: Colubridae) from CostaRica. Texas Journal of Science 56: 171–174.Goldberg, S. R. 2004c. Notes on reproduction in theCentral American coral snake, Micrurus nigrocinctus(Serpentes: Elapidae) from Costa Rica. CaribbeanJournal of Science 40: 420–422.Goldberg, S. R. 2006a. Note on the testicular cycle of theCosta Rica water snake, Hydromorphus concolor(Serpentes: Colubridae). Bulletin of the MarylandHerpetological Society 42: 169–170.Goldberg, S. R. 2006b. Reproductive cycle of the salmon-bellied racer, Mastigodryas melanolomus (Serpentes,Colubridae), from Costa Rica. Phyllomedusa 5: 145–148.Goldberg, S. R. 2007. Note on the testicular cycle ofGodman’s earth snake, Geophis godmani (Serpentes:Colubridae) from Costa Rica. Bulletin of the ChicagoHerpetological Society 42: 7–8.Goldberg, S. R. and W. S. Parker. 1975. Seasonal testicularhistology of the colubrid snakes, Masticophistaeniatus and Pituophis melanoleucus. Herpetologica31: 317–322.Saint Girons, H. 1982. Reproductive cycles of male snakesand their relationships with climate and femalereproductive cycles. Herpetologica 38: 5–16.Savage, J. M. 2002. The Amphibians and Reptiles of CostaRica: A Herpetofauna Between Two Continents,Between Two Seas. Chicago. The University ofChicago Press. 934 pp.Solórzano, A. 2004. Snakes of Costa Rica: Distribution,Taxonomy, and Natural History. Instituto Nacional deBiodiversidad, Costa Rica. 791 pp.Zug, G. R., S. B. Hedges and S. Sunkel. 1979. Variationin reproductive parameters of three neotropical snakes,Coniophanes fissidens, Dipsas catesbyi, andImantodes cenchoa. Smithsonian Contributions inZoology 300: 1–20.COSTA RICA – Alajuela, 131127; Cartago154316; Heredia 154306, 154307, 154313,154315, 154317, 154320, 154322, 154324,Appendix I – Specimens Examined154326, 154329, 154334; Limón 154311,154312, 154323, 154333; Puntarenas 154308,154310, 154314, 154319, 154321.Notes on reproduction of Rhadinea decorata (Serpentes, Colubridae)

Notes on reproduction of the adorned graceful brown snake, Rhadinea decorata (Serpentes, Colubridae), from Costa Rica

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Notes on reproduction of the adorned graceful brown snake, Rhadinea decorata (Serpentes, Colubridae), from Costa Rica

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