Helicops modestus (Ophidia: Dipsadidae): reproduction
Helicops modestus (Ophidia: Dipsadidae): reproducción
Danüsa C. Maia, Angélica G. Da Silva, Silvia R. Travaglia-Cardoso
Museu Biológico, Instituto Butantan, Avenida Vital Brasil, 1500, 05503-900. São Paulo, SP, Brasil. <danusa.maia@butantan.gov.br>
]]>Recibido: 30/01/2014.
Aceptado: 07/04/2015.
RESUMEN
Los datos sobre la reproducción de serpientes son escasos, sobre todo porque es difícil encontrar a estos organismos en su hábitat natural. Se proporcionan algunos datos inéditos sobre la reproducción de Helicops modestus (Günther, 1861), un dipsádido con amplia distribución geográfica en Brasil.
The genus Helicops is widely distributed in South America (Giraudo 2001). The species Helicops modestus (Günther, 1861) occurs in Southern, Southeastern and Midwestern Brazil (Costa et al. 2009, Braz 2013, Kawashita-Ribeiro et al. 2013), with one record for the Northeastern region (Freitas & Silva 2011). They have morphological adaptations to the aquatic environment of different habitats (Cunha & Nascimento 1978, Scartozzoni 2005). H. modestus feeds mainly on fishes and occasionally on amphibians (Costa et al. 2009, Marques et al. 2009, Barbo et al. 2011). It is a viviparous species with some aspects of its reproduction unknown. This note presents information on birth, litter size and mass, and unpublished data about sexual dimorphism in H. modestus neonates.
One pregnant specimen of H. modestus,590 mm snout-vent length (SVL), 180 mm tail length (TL), and 144 g mass after parturition, was collected in Barueri, São Paulo (23°51'S 46°87'W) and brought to Instituto Butan-tan where it was kept in captivity. On January 31, 2011, it gave birth to 24 snakes. The relative clutch mass (RCM, see Shine, 1980) was 0.34. The RCM was high but similar to the values reported for other snakes of the genus Heli-cops (see Scartozzoni 2009).
Male neonates (n = 15 / mean ± SD) measured 146 ± 11.8 mm (SVL, range = 120-160 mm); 56.3 ± 5.8 mm (TL, range = 45-60 mm), and weighed 2.03 ± 0.4 g (range = 1.1-2.5 g). Female neonates (n = 9 / mean ± SD) measured 146.1 ± 10.2 mm (SVL, range = 120-155 mm); 44.4 ± 6.8 mm (TL, range = 30-50 mm) and weighed 2.1 ± 0.3 g (range = 1.3-2.3 g).
]]> Sexual dimorphism among adults is well reported for snakes, but few studies show the sexual dimorphism in neonates (King et al. 1999). Male and female neonates of this litter did not differ significantly in mean SVL (t = 0.02; P = 0.98) or mass (t = 0.42; P = 0.67), but sexual dimorphism in tail length was observed with males being born with a longer tail (t = 4.54; P = 0.0002). For H. modestus, sexual dimorphism in body size (females larger) and tail size (males with larger tail) was reported in adults (Scartozzoni 2009). Therefore, here we suggest ontogenetic variation in SVL, since among adults the females are significantly larger (SVL). Additional neonate data of this species should be analyzed to corroborate our findings.
LITERATURE CITED
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