Reproductive Ecology of Dipsadine Snakes, with Emphasis on South American Species

Herpetologica, 64(2), 2008, 168–179 E 2008 by The Herpetologists’ League, Inc.

REPRODUCTIVE ECOLOGY OF DIPSADINE SNAKES, WITH EMPHASIS ON SOUTH AMERICAN SPECIES

1,4,5 2 3 4 LI´GIA PIZZATTO ,MAURIĆIO CANTOR ,JULIANA LIMA DE OLIVEIRA ,OTAVIO A. V. MARQUES , 2 3 VINICIUS CAPOVILLA , AND MARCIO MARTINS 1Po´s-Graduaçaõ em Ecologia, Depto. de Zoologia, Universidade Estadual de Campinas, CP 6109, 13083-970, Campinas, SP, Brazil 2Graduaçaõ em Cieˆncias Biolo´gicas, Depto. de Zoologia, Universidade Estadual de Campinas, CP 6109, 13083-970, Campinas, SP, Brazil 3Departamento de Ecologia, Instituto de Biocieˆncias, Universidade de Saõ Paulo, Rua do Mataõ, Travessa 14 s/n, 05508-090, Saõ Paulo, SP, Brazil 4Laborato´rio Especial de Ecologia e Evoluçaõ, Instituto Butantan, Av. Dr. Vital Brazil 1500, 05503-900, Saõ Paulo, SP, Brazil

ABSTRACT: A relatively large amount of variation occurs in the reproductive ecology of tropical snakes, and this variation is generally regarded as being a consequence of seasonality in climate and prey availability. In some groups, even closely related species may differ in their reproductive ecology; however, in others it seems to be very conservative. Here we explore whether characters related to reproduction are phylogenetically constrained in a monophyletic group of snakes, the subfamily Dipsadinae, which ranges from Mexico to southern South America. We provide original data on reproduction for Leptodeira annulata, Imantodes cenchoa, and three species of Sibynomorphus from southern, southeastern and central Brazil, and data from literature for other species and populations of dipsadines. Follicular cycles were seasonal in Atractus reticulatus, Dipsas albifrons, Hypsiglena torquata, Leptodeira maculata, L. punctata, Sibynomor- phus spp. and Sibon sanniola from areas where climate is seasonal. In contrast, extended or continuous follicular cycles were recorded in Dipsas catesbyi, D. neivai, Imantodes cenchoa, Leptodeira annulata, and Ninia maculata from areas with seasonal and aseasonal climates. Testicular cycles also varied from seasonal (in H. torquata) to continuous (in Dipsas spp., Leptodeira annulata, L. maculata, N. maculata and Sibynomorphus spp.). Most dipsadines are small (less than 500 mm SVL), and females attain sexual maturity with similar relative body size than males. Sexual dimorphism occurred in terms of SVL and tail length in most species, and clutch size tended to be small (less than five eggs). Combat behavior occurs in Imantodes cenchoa, which did not show sexual size dimorphism. Reproductive timing, for both females and males, varied among species but in general there were no differences between the tribes of Dipsadinae in most of the reproductive characteristics, such as mean body size, relative size at sexual maturity, sexual size and tail dimorphism, duration of vitellogenesis or egg-carrying in oviducts. Key words: Dipsadinae; Fecundity; Follicular cycle; Reproduction; Sexual size dimorphism; Sexual tail dimorphism; Testicular cycle

REPRODUCTIVE cycles of snakes vary from colubrid snake from tropical Australia (Tropi- highly seasonal to continuous. In temperate donophis mairii), abiotic factors such as areas, snakes usually reproduce only during seasonal availability of moist incubation con- the warmer months (usually spring) and many ditions were more important than biotic species present nonannual cycles. In tropical factors (e.g., higher predation on eggs or areas, however, cycles tend to be more hatchlings, or food availability for hatchlings) variable (Fitch, 1982; Seigel and Ford, on influencing reproductive timing. 1987). This higher variability can be partially Recent studies on the evolution of ecolog- explained by greater climatic complexity ical characters in Neotropical snakes have (Greene, 1997) and food availability in tropical shown that characters related to defense areas (Santos et al., 2005; Seigel and Ford, against predators seem to have diversified 1987). Climatic factors may be an important apparently quickly in Neotropical snakes, with variable affecting seasonality in reproductive a large amount of variation within clades (e.g., cycles of tropical snakes (Pizzatto and Martins, 1996). In contrast, habitat and Marques, 2002, 2006). For example, Brown microhabitat use, as well as diet and many and Shine (2006) provided evidence that, for a other characters related to feeding, seem to be conservative, i.e., they have experienced few changes during the lineage’s history and, 5 CORRESPONDENCE: e-mail, [email protected] consequently, the snake groups studied show

168 June 2008] HERPETOLOGICA 169 little contemporary variation in these charac- characters, such as sexual maturity and ters (e.g., Martins et al., 2001, 2002). Charac- dimorphism, body sizes, reproductive cycles ters related to reproduction in Neotropical and clutch size in snakes of the tribe snakes seem to be relatively conservative in Dipsadini; and (2) investigate how those some phylogenetic lineages (Almeida-Santos characters differ between the tribes Dipsadini and Salomaõ, 2002; Almeida Santos at al., and Leptodeirini. 2006; Marques, 1996; Marques et al., 2006; Pizzatto and Marques, 2007; Pizzatto et al., MATERIALS AND METHODS 2007a, 2008), although in other groups even Original data on adult Leptodeira annulata closely related species may differ widely in (n 5 181), Imantodes cenchoa (n 5 36), their reproductive ecology (e.g., Marques, Sibynomorphus mikanii (n 5 144), S. neu- 1996). Despite the efforts to study the wiedi (n 5 126), and S. ventrimaculatus (n 5 reproductive biology of tropical snakes in the 111) were obtained from specimens deposit- last few decades (e.g., Balestrin and Di- ed in the collections of Instituto Butantan Bernardo, 2005; Marques, 1996; Pizzatto and (IB), Museu de Histo´ria Natural da Uni- Marques, 2002; Vitt, 1987), it is still not versidade Estadual de Campinas (ZUEC), possible to recognize patterns in many groups, Universidade Federal de Santa Maria especially in areas where species diversity is (ZUFSM), Pontifıćia Universidade Cato´lica high, such as in the Neotropics (but see do Rio Grande do Sul (MCP), and Museu de Almeida-Santos and Salomaõ, 2002). Histo´ria Natural do Capaõ da Imbuia The subfamily Dipsadinae (Vidal et al., (MHNCI). Specimens of L. annulata were 2000; Zaher, 1999) is composed of small, collected in a range of localities between 11u slender snakes which occur from Mexico to 479 Nand23u 359 S, and 39u 439 Eand56u southern South America (Ferrarezzi, 1994; 059 W; those of I. cenchoa are from 21u 119 N Zaher, 1999). The monophyletism of Dipsa- to 26u 559 Sand45u 249 Eto52u 069 W; S. dinae is suggested by both morphological and mikanii from 20u 169 Nto23u 589 Sand45u molecular data (Cadle, 1984; Vidal et al., 2000; 429 Eto51u 209 W; S. neuwiedi from 20u 219 Wallach, 1995; Zaher, 1999), and the subfam- Nto25u 009 Sand40u 399 Eto49u 429 W; ily is apparently the sister group of all other and S. ventrimaculatus from 27u 289 Nto30u xenodontines (Vidal et al., 2000). Two appar- 529 Sand51u 019 Eto54u 289 W. For each ently monophyletic clades comprise the Dip- snake we collected data on: (1) snout–vent sadinae: the tribes Dipsadini, composed of length (SVL), (2) length of the right testis, (3) aglyphous, relatively smaller, earthworm/mol- diameter of deferent duct, proximal to the lusk-eating snakes (e.g., Adelphicos, Atractus, cloaca, (4) diameter of the largest ovarian Geophis, Ninia, Tropidodipsas, Sibon, Dipsas follicle or oviductal egg, and (5) number of and Sibynomorphus), and Leptodeirini, which well developed follicles in secondary vitello- is composed of aglyphous or opisthoglyphous, genesis (.10 mm) and eggs. relatively larger, lizard/frog-eating snakes Gravid S. mikanii and S. neuwiedi received (e.g., Eridiphas, Hypsiglena, Imantodes, Lep- at Instituto Butantan (IB) were kept in todeira and Pseudoleptodeira (see Cadle, captivity until oviposition. Data on other 1984; Cadle and Greene, 1993; Ferrarezzi, species of dipsadines were obtained from 1994; Martins and Oliveira, 1999; Rodrı´guez- published papers. In these cases we used only Robles et al., 1999; Vidal et al., 2000; Vitt, information that confirmed reproductive tim- 1996; Zaher, 1999). ing and fecundity in each species. Many As a further attempt to understand the published sources were not used because they extent to which reproductive characters of represent only a few, or casual, records that Neotropical snakes are conservative (cf. Al- were not conclusive or comparable to our meida-Santos and Salomaõ, 2002), we here data. Data on testicular cycles of Hypsiglena explored the variation in reproductive ecology torquata, Leptodeira maculata, L. punctata in the subfamily Dipsadinae based on original and Ninia maculata came from histological and literature data. Specifically, our aim is to: analyses (Diller and Wallace, 1986; Goldberg, (1) conduct an overview of reproductive 2001, 2004a,b). 170 HERPETOLOGICA [Vol. 64, No. 2

Females were considered mature if they Yoshida, 1993). Variation in testis length and had follicles in secondary vitellogenesis, ovi- diameter of deferent duct (dependent vari- ductal eggs (cf. Shine, 1978) or folded ables) were compared among seasons (factors) oviducts (which indicate recent oviposition). using ANCOVA because both variables were Males were considered mature when they had significantly correlated to snake SVL (covari- turgid testes and convoluted deferent ducts ate) (Zar, 1999). (cf. Shine, 1980; Slip and Shine, 1988). A sexual size dimorphism index (SSD) was RESULTS calculated according to Shine (1994): mean Mean body sizes of adult snakes differed body size of the largest sex divided by mean among species in the dipsadines (Table 1). All body size of the smallest sex, minus one. By species, except I. cenchoa had a mean SVL , convention, positive values represent females 600 mm, and the smallest species was N. larger than males and negative values repre- maculata (mean SVL 5 226 mm; Table 1). sent males larger than females (Shine, 1994). When mean SVL is compared between the Size at maturity, represented by the SVL of Dipsadina and the Leptodeirina, neither those the smallest mature snake in the samples, and of females (means 403.6 and 517.6 mm, relative tail length were presented as the respectively) nor those of males (means 372.7 proportions of the mean body size and and 457.8 mm, respectively) were significantly analyzed after transformation to the arcsine different (t 521.50, P 5 0.156; t 521.04, P of their squared root. All variables were tested 5 0.318; respectively). Males were significantly for normality and homoscedasticity prior to smaller than females in all species (L. annulata, analyses (Zar, 1999). t 5 8.09, df 5 179, P , 0.001; S. mikanii, t 5 Sexual dimorphism was investigated in 9.05, df 5 147, P , 0.001; S. neuwiedi, t 5 terms of mean SVL, proportional size at 9.25, df 5 125, P , 0.001; S. ventrimaculatus, t maturity (PSM) and relative tail length 5 9.48, df 5 110, P , 0.001; see original (RTL). We compared these variables between papers for results for other species), except for sexes, using two-tailed t-Student test (Zar, I. cenchoa (t 5 0.25, df 5 34, P 5 0.801). 1999). Sexual dimorphism in tail length was Sexual size dimorphism ranged from 0.009 analyzed in L. annulata, I. cenchoa and in I. cenchoa to 0.27 in S. ventrimaculatus. Sibynomorphus spp. with ANCOVA, using The value of SSD was lower than 0.1 in all tail length as the dependent variable, SVL as species of Dipsas,inI. cenchoa and in a the covariate, and sex as the factor (Zar, 1999). population of L. annulata from the Brazilian This analysis was not performed for the other Amazon (Table 1). Sexual size dimorphism species because we did not have access to the was not significantly different between Dipsa- raw data sets. dini and Leptodeirini (means 0.159 and 0.156; We used the Student’s t-test (Zar, 1999) to t 5 0.06, P 5 0.955). Sexual size dimorphism test for differences in mean SVL, PSM, RTL, decreased with increasing snake size; snake SSD, clutch size, and duration of reproductive size explained about one third of the variation cycles between the tribes and RTL between in SSD in males (r2 5 0.35, P 5 0.034) and habitat use categories (terrestrial/fossorial and one fifth in females (r2 5 0.18, P , 0.001). arboreal/semi-arboreal). To test whether SSD Females of most species attained sexual was affected by body size, we used linear maturity at 75–85% of mean adult SVL and regressions, separately for males and females males at 70–80% (Table 1), and this intersex- (Zar, 1999). To test whether clutch size is ual difference was not significant (t 5 1.42, P affected by body size in L. annulata, I. 5 0.168). When the proportion of mean adult cenchoa and Sibynomorphus spp., we used SVL at which sexes attained sexual maturity is linear regressions. Data were log-transformed compared between the Dipsadini and the as required (Zar, 1999). Leptodeirini, neither females (means 79.3 and Testis length indicates sperm production 77.3%, respectively) nor males (means 77.0 (cf. Volsøe, 1944), and deferent duct diameter and 73.1%) were significantly different (t 5 can indicate sperm storage (Almeida-Santos et 0.49, P 5 0.640, t 520.70, P 5 0.500; al., 2006; Sever et al., 2002; Yokoyama and respectively). ue2008 June

TABLE 1.—Mean snout–vent length (SVL) in adult females and males, sexual maturity and sexual size dimorphism index (SSD) in dipsadine snakes. Means are followed by standard deviation, range in parenthesis and sample size (n). All measurements are in mm.

proportional 171 HERPETOLOGICA ] Species SVL adult RR (mean 6 SD) SVL adult == (mean 6 SD) SVL at maturity SSD Range Reference Dipsadini Atractus 300.1 6 30.0 249.9 6 24.4 RR: 80.6% 0.20 Southern Brazil (29u 399 N, 30u 049 S, Balestrin and Di reticulatus (242–370, n 5 43) (198–295, n 5 58) ==: 79.2% 50u 319 E, 51u 139 W) Bernardo, 2005 Dipsas albifrons 470.5 6 45.5 435.9 6 57.7 RR: 85.0% 0.08 Southern Brazil (26u 189 N, 22u 569 S, Hartmann et al., (400–590, n 5 63) (325–540, n 5 50) ==: 74.6% 48u 509 E, 49u 149 W) 2002 Dipsas catesbyi 494.19 6 63.91 463.69 6 53.78 RR: 67.0% 0.06 Northeastern Brazil (14u 009 N, 18u 009 Alves et al., 2005 (331–640, n 5 54) (341–575, n 5 65) ==: 73.5% S, 39u 009 E, 41u 009 W) Dipsas catesbyi 402.1 6 48.6 — RR: 84.0% Amazonia and tropical Forest region Zug et al., 1979 (338–542, n 5 51) (6u 489 N, 17u 279 S, 48u 309 E, 76u 589 W) Dipsas neivai 584.41 6 86.67 521.79 6 81.29 RR: 73.9% 0.05 Northeastern Brazil (14u 009 N, 18u 009 Alves et al., 2005 (432–820, n 5 91) (298–702, n 5 99) ==: 57.1% S, 39u 009 E, 41u 009 W) Geophis 333.6 6 26.4 — RR: 88.4% — Costa Rica (10u 169 N, 9u 339 S, 83u 30E, Sasa, 1993 brachycephalus (295–365, n 5 12) ==:— 84u 489 W) Ninia maculata 226.0 6 22.0 201.0 6 15.0 RR: 77% 0.12 Costa Rica (11u 009 N, 9u 009 S, 83u 009 Goldberg, 2004b (175–275, n 5 25) (179–228, n 5 16) ==: 89% E, 85u 309 W) Sibynomorphus 437.6 6 61.3 352.8 6 37.7 RR: 77.5% 0.24 Southeastern Brazil (20u 169 N, 23u 589 This work mikanii (339–580, n 5 92) (280–510, n 5 52) ==: 79.4% S, 45u 429 E, 51u 209 W) Sibynomorphus 526.4 6 58.9 422.5 6 66.8 RR: 78.8% 0.25 Southern and Southeastern Brazil This work neuwiedi (415–660, n 5 72) (254–541, n 5 54) ==: 60.1% (20u 219 N, 25u 009 S, 40u 399 E, 49u 429 W) Sibynomorphus 422.4 6 48.4 333.9 6 45.0 RR: 81.7% 0.27 Southeastern Brazil (27u 289 N, 30u 529 This work ventrimaculatus (345–577, n 5 71) (240–413, n 5 40) ==: 71.9% S, 51u 019 E, 54u 289 W) Sibon sanniola 240.6 6 22.6 ? RR: 83.5% — Yucata´n Peninsula, Mexico Kofron, 1983 (201–292, n 5 42) (22u 009 N, 20u 009 S, 87u 009 E, 90u 009 W) Leptodeirini Hypsiglena 360.0 6 45.4 300.0 6 27.2 RR: 86% 0.20 Arizona, EUA (37u 009 N, 31u 309 S, Goldberg, 2001 torquata (310–503, n 5 42) (237–368, n 5 67) ==: 79% 109u 009 E, 114u 309 W) Imantodes cenchoa 715.9 6 67.7 — RR: 86.7% — Equatorial and Tropical Forest region Zug et al., 1979 (621–901, n 5 33) (15u 539 N, 0u 039 S, 73u 159 E, 92u 489 W) Imantodes cenchoa 771.2 6 67.9 764.2 6 95.0 RR: 83.0% 0.009 S, SE Brazil (21u 119 N, 26u 559 S, 45u 249 This work (640–880, n 5 18) (601–972, n 5 18) ==: 78.6% E, 52u 069 W) Leptodeira 595.2 6 89.1 502.2 6 60.2 RR: 76.3% 0.19 Central and Southeastern Brazil This work annulata (454–841, n 5 105) (367–644, n 5 80) ==: 73% (11u 479 N, 23u 359 S, 39u 439 E, 56u 059 W) Leptodeira 545.6 6 11.5 498.6 6 12.6 RR: 91.1% 0.09 Amazon region (0u 009 N, 10u 009 Vitt, 1996 annulata (497–609, n 5 12) (431–584, n 5 18) ==: 86.4% S, 50u 009 E, 78u 009 W) Leptodeira 470.1 6 82.8 384.4 6 52.7 RR: 67% 0.22 SW Me´xico (26u 009 N, 16u 009 S, Goldberg, 2004a maculata (317–630, n 5 19) (280–444, n 5 27) ==: 73% 98u 009 E, 109u 009 W) Leptodeira 391.5 6 59.6 338.2 6 41.1 RR: 75% 0.16 W Me´xico (26u 009 N, 21u 009 S, Goldberg, 2004a punctata (292–523, n 5 26) (276–451, n 5 41) ==: 82% 103u 009 E, 109u 009 W) 172 HERPETOLOGICA [Vol. 64, No. 2

TABLE 2.—Tail length (as % of SVL) in males and females, mean clutch size and habitat of dipsadine snakes.

Species Tail length (as % of SVL) Mean clutch size (6SD) Habitat Reference Dipsadini Atractus reticulatus RR: 11.6%, 2.7 6 0.8 (1–3, n 5 6) Fossorial Balestrin and ==: 15.7%1 Di-Bernardo, 2005 Dipsas albifrons — 3.9 6 1.8 (1–8, n 5 33) Arboreal Hartmann et al., 2002 Dipsas catesbyi RR: 36.5%, 2.0 6 0.82 (1–3, n 5 10) Arboreal Zug et al., 1979 ==: 39.0%2 Dipsas catesbyi — 3.63 6 1.66 (1–6, n 5 13) Arboreal Alves et al., 2005 Dipsas neivai — 3.91 6 1.95 (1–8, n 5 22) Arboreal Alves et al., 2005 Geophys brachycephalus RR: 17.3%, ==: — 4.2 6 1.17 (3–6, n 5 6) Terrestrial- Sasa, 1993 fossorial Ninia maculata — 2.9 6 1.1 (1–5, n 5 14) Semi-fossorial Goldberg, 2004b Sibynomorphus mikanii RR: 20.4%, 5.7 6 1.7 (3–10, n 5 29) Terrestrial This work ==: 24.8%1 Sibynomorphus neuviedi RR: 26.9%, 6.4 6 2.4 (4–12, n 5 14) Semi-arboreal This work ==: 31.1%1 Sibynomorphus RR: 22.7%, 4.8 6 1.0 (3–7, n 5 33) Terrestrial This work ventrimaculatus ==: 26.8%1 Sibon sanniola — 3.1 6 0.70 (2–5, n 5 28) ? Kofron, 1983 Leptodeirini Hypsiglena torquata RR: 15.0%, 3.2 6 1.5 (1–6, n 5 9) Terrestrial Goldberg, 2001; ==: 20.0%2 Runquist, 2002 Imantodes cenchoa — 2.0 6 0.71 (1–3, n 5 5) Arboreal Zug et al., 1979 Imantodes cenchoa RR: 45.0%, 3.3 6 1.70 (1–7, n 5 13) Arboreal This work ==: 47.0%1 Leptodeira annulata ==: 30.0%, 7.3 6 2.53 (3–13, n 5 23) Arboreal This work, but see ==: 39.0%1 also Duellman, 1958 Leptodeira maculata — 8.7 6 1.5 (7–11, n 5 7) Arboreal Goldberg, 2004a Leptodeira punctata — 7.8 6 1.7 (6–11, n 5 9) Arboreal Goldberg, 2004a 1 Statistically significant differences. 2 No statistical tests performed, but differences are apparent.

Relative tail length of male and female to August (Fig. 1A). In I. cenchoa, vitellogenic snakes did not differ significantly between follicles were found in September and eggs Dipsadini and Leptodeirini (means 22.6% were recorded from November to January and 30.0% of body length for females, and (Fig. 1B). Among the Dipsadina, seasonal 27.5% and 35.3% for males; t 520.92, P 5 vitellogenesis was recorded for S. mikanii 0.388, and t 520.966, P 5 0.371, respectively; and S. neuwiedi mostly from July to Decem- Table 2). When all species of Dipsadinae are ber and eggs were recorded from late August considered together, tails were significantly to February (Fig. 1C,D). In S. ventrimacula- longer in arboreal and semi-arboreal species tus, vitellogenesis was shorter, occurring than in fossorial and terrestrial species, both for mostly from October to December, and eggs females and males (medians 34.5% and 17.4% were recorded from October to February of body length for females, and 39.0% and (Fig. 1E). Thus, a seasonal reproductive cycle, 21.8% for males; t 524.03, P 5 0.005, and t 5 with vitellogenesis restricted to the warmer 24.18, P 5 0.004, respectively; Table 2). Tails and rainier months of the year, was observed were also significantly longer in males than in in Sibynomorphus spp. in our analyses, and females of L. annulata, I. cenchoa, S. mikanii, also in Atractus reticulatus, Dipsas albifrons S. neuwiedi, and S. ventrimaculatus (AN- (from coastal Atlantic Forest in southern COVA, all F . 2.0, all P , 0.025) and in other Brazil), H. torquata, L. maculata, L. punctata dipsadines (Table 2, for statistical analyses, see and Sibon sanniola in literature data (see data in original papers). Fig. 2). In Dipsas catesbyi and D. neivai from Among the Leptodeirina, in Leptodeira the coastal Atlantic Forest in northeastern annulata, follicles in secondary vitellogenesis Brazil and in N. maculata from Costa Rica were found from late February and March to cycles were continuous (Fig. 2). Leptodeira early December and oviductal eggs from May annulata, Geophis brachycephalus and prob- June 2008] HERPETOLOGICA 173

FIG. 1.—Seasonal variation in the diameter of the largest ovarian follicle (full circles) and oviductal eggs (empty circles) in Leptodeira annulata, Imantodes cenchroa and Sibynomorphus spp. from Brazil. Triangles represent egg- laying in snakes received gravid at IB. Follicles above dotted line were in secondary vitellogenesis. ably I. cenchoa had extended cycles (about to be a function of female SVL (Fig. 4). When eight months; Fig. 2). Duration of vitellogen- I. cenchoa populations and D. neivai (all with esis, occurrence of oviductal eggs or the low relative fecundity) are removed from the duration of complete reproductive period analysis the relationship between SVL and (months in which vitellogenesis and/or pres- clutch size become positive and significant (r2 ence of oviductal eggs occurred) did not differ 5 0.33, P 5 0.025, Fig. 4). between Dipsadina (means 8.4, 7.1 and Testis length and deferent duct diameter 15.5 mo, respectively) and Leptodeirina (5.8, did not differ significantly among seasons in L. 5.0 and 10.8 mo, respectively; t 5 1.82, P 5 annulata and Sibynomorphus spp. (Table 3), 0.093 for vitellogenesis duration, t 5 1.37, P 5 which indicates continuous sperm production 0.194 for duration of eggs in oviducts, and t 5 and absence of sperm storage by males. Data 1.63, P 5 0.127 for the complete cycle). on I. cenchoa were not sufficient to compare Clutch size is relatively small in the either right testis length or deferent duct dipsadines (Table 2) and is not significantly diameter among seasons. different between the Dipsadini and the Sperm production occurred throughout Leptodeirini (means 5.3 and 3.9 eggs, respec- the year in the Dipsadini and in spring- tively; t 5 1.47, P 5 0.160). Clutch size was summer in the only species of Leptodeirini not different between terrestrial/fossorial studied. Sperm was found in the deferent duct snakes and arboreal/semiarboreal ones (t 5 throughout the year in all Dipsadini except N. 0.45, P 5 0.656). Snout–vent length was maculata (in which it occurred in spring- significantly related to clutch size in S. mikanii 2 autumn), and in spring-summer in both (r 5 0.39, P 5 0.037; Fig. 3A), S. neuwiedi species of Leptodeirini studied (Table 4). (r2 5 0.63, P 5 0.015; Fig. 3B), S. ventrimaculatus (r2 5 0.59, P , 0.001; Fig. 3C) and I. cenchoa (r2 5 0.68, P 5 0.010; Fig. 3E), but DISCUSSION not in L. annulata (data log-transformed, r2 5 In all species of the subfamily Dipsadinae 0.34, P 5 0.101; Fig. 3D). When all species for which data on size at sexual maturity were are considered together, clutch size seems not available, males and females attained sexual 174 HERPETOLOGICA [Vol. 64, No. 2

FIG. 2.—Reproductive cycles in Dipsadinae snakes. Lines: Vitellogenesis time. Boxes: Oviductal eggs or egg-laying. BRA 5 Brazil, USA 5 United States of America, MEX 5 Mexico, COR 5 Costa Rica. Full lines and boxes 5 observed, dotted lines and boxes 5 inferred. maturity at similar relative body sizes. The 2008), a clade within the Xenodontinae (Vidal degree of sexual size dimorphism (SSD) et al., 2000; Zaher, 1999). Males larger than decreased with increasing body size in the females or absence of sexual dimorphism dipsadines. This pattern is opposite to that usually occurs in species in which males found in the tribe Xenodontini (Pizzatto et al., exhibit combat behavior during the mating June 2008] HERPETOLOGICA 175

FIG. 3.—Relationship between clutch size and female snout–vent length in Leptodeira annulata, Imantodes cenchroa and Sibynomorphus spp. from Brazil. season (Shine, 1994). The lowest SSD occurs Sexual dimorphism also occurs in tail length in Imantodes cenchoa and this is the only in all species in both tribes (Dipsadini: A. species in which the largest body size is reticulatus, Balestrin and Di-Bernardo, 2005; attained by males and not females. Male-male D. albifrons, Hartmann et al., 2002; D. fighting behavior and mating was recorded in catesbyi, Zug et al., 1979; Sibynomorphus this species in October (spring) in the spp., this study; Leptodeirini: H. torquata, Brazilian Amazon (see Santos-Costa and Runquist, 2002; I. cenchoa, Zug et al., 1979, Prudente, 2005) and, an aggregation of three this study; L. annulata, Vitt, 1996, this study). males and one female in a Peruvian rainforest A longer tail is expected in males due to the in May (spring) (Doan and Arriaga, 1999) also presence of the hemipenes and their retractor suggest combat. Male-male ritual combat has muscles (King, 1989). However, in many not been reported in any other dipsadine, arboreal snakes this dimorphism is absent xenodontines, nor in the Heterodon-Farancia (Fowler and Saloma˜o, 1994; Pizzatto and group, the basal lineage of both clades (see Marques, 2007) probably because a long tail Vidal et al., 2000). Thus, either ritual combat may be advantageous for arboreal life (Lilly- remains unnoticed due to elusive habits of the white and Henderson, 1993; Martins et al., snakes and suboptimal research efforts or it is 2001). Tail dimorphism occurs in both terres- an autapomorphy of Imantodes cenchoa with- trial and arboreal dipsadines, but tail is in this large clade of colubrids. proportionally much longer in arboreal and 176 HERPETOLOGICA [Vol. 64, No. 2

seasonal climates seem to restrict the female cycles in some species, such as D. albifrons and S. ventrimaculatus from southern Brazil. These species show more restricted timing of vitellogenesis than their congenerics from lower latitudes. Testicular cycles are not available for most species of dipsadines; however, our data indicate that it is variable within this subfamily. Hypsiglena torquata from temperate areas has a seasonal sperm production, occurring in the warmest periods of the year. Despite the records of seasonal sperm production in many tropical snakes (Fitch, 1982; Shine, 1977), most tropical species of dipsadines show FIG. 4.—Relationship between mean clutch size and continuous testicular activity. Cycles also mean female snout–vent length in Dipsadinae snakes. differed among sexes in the same species. Circles 5 arboreal/semi-arboreal species, triangles 5 terrestrial, squares 5 fossorial. Data from: Alves et al., For example, while females of Sibynomorphus 2005, Balestin and Di-Bernardo, 2005; Goldberg, 2001, spp. have seasonal cycles, males produce 2004a,b; Hartmann et al., 2002, Kofron, 1983; Sasa, 1993; sperm continuously, indicating that sperm Vitt, 1996; Zug et al., 1979; this work. production is less costly than egg production (Trivers, 1972), at least in tropical snakes. semi-arboreal species of dipsadines than in In general, dipsadine snakes produce small terrestrial and fossorial species, as observed in clutches, probably because of the small size of other studies (e.g., Hartmann and Marques, these snakes. Also, the very slender body in 2005; Martins et al., 2001; Pizzatto and arboreal species such as L. annulata and I. Marques, 2007; Pizzatto et al., 2007b). cenchoa can strongly reduce body cavity space Reproductive cycles vary among snake to carry eggs, resulting in smaller clutches (see species and also can differ between females Pizzatto et al., 2007b). Thus, although female and males (Seigel and Ford, 1987). Dipsa- body size is important in determining clutch dines usually show seasonal reproductive size for some species, other factors may cycles in females, but duration is variable influence this trait (e.g., habitat use, feeding among species. Some species occurring in habits, phylogeny). areas with a seasonal climate exhibit cycles Most reproductive characters we analyzed restricted to the warm and rainier seasons, but for the dipsadines seem to be conservative L. annulata seems to have extended follicular within the tribe. The tribes Dipsadini and cycles even in areas where climate is seasonal Leptodeirini did not differ in the amount of (e.g., southeastern and central Brazil between SSD, the proportion of mean SVL at which 9u 349 N and 23u 359 S). In contrast, more sexes attained sexual maturity, relative tail

TABLE 3.—Statistical results of variation in right testis length and diameter of deferent duct among seasons in four dipsadine snakes from Brazil.

Species Right testis length ANCOVA Deferent duct diameter ANCOVA Dipsadini Sibynomorphus mikanii Slopes: F3,32 5 0.11, P 5 0.954 Insufficient data Intercept: F3,33 5 2.22, P 5 0.102 Sibynomorphus neuwiedi Slopes: F3,25 5 1.01, P 5 0.403 Slopes: F3,22 5 0.20, P 5 0.827 Intercept: F3,26 5 0.96, P 5 0.423 Intercept: F3,23 5 2.58, P 5 0.076 Sibynomorphus ventrimaculatus Slopes: F3,22 5 0.95, P 5 0.434 Slopes: F3,21 5 1.48, P 5 0.248 Intercept: F3,23 5 1.07, P 5 0.379 Intercept: F3,22 5 0.08, P 5 0.967 Leptodeirini Leptodeira annulata Slopes: F3,71 5 0.74, P 5 0.530 Slopes F3,69 5 1.86, P 5 0.144 Intercept: F3,72 5 0.80, P 5 0.495 Intercept: F3,70 5 0.49, P 5 0.688 ue2008 June EPTLGC 177 HERPETOLOGICA ]

TABLE 4.—Male reproductive cycles in dipsadine snakes.

Species Sperm production Sperm in deferent duct Location of collection Reference Dipsadini Dipsas neivai Throughout the year Throughout the year Northeastern Brazil Alves et al., 2005 (14u 009 N, 18u 009 S, 39u 009 E, 41u 009 W) Dipsas catesby Throughout the year Throughout the year Northeastern Brazil (14u 009 N, 18u 009 S, Alves et al., 2005 39u 009 E, 41u 009 W) Hypsyglena torquata Spring–summer Spring–Summer Arizona – USA (37u 009 N, 31u 309 S, 109u 009 E, Diller and Wallace, 114u 309 W), Idaho – USA (49u 00N, 42u 009 S, 1986; Goldberg, 2001, 112u 309 E, 116u 309 W) Ninia maculata Throughout the year Spring–Autumn Costa Rica (11u 009 N, 9u 009 S, 83u 009 E, Goldberg, 2004b 85u 309 W) Sibynomorphus mikanni Throughout the year Throughout the year Southeastern Brazil (20u 169 N, 23u 589 S, This work 45u 429 E, 51u 209 W) Sibynomorphus neuwiedii Throughout the year Throughout the year Southeastern Brazil (20u 219 N, 25u 009 S, This work 40u 399 E, 49u 429 W) Sibynomorphus Throughout the year Throughout the year Southern Brazil (27u 289 N, 30u 529 S, This work ventrimaculatus 51u 019 E, 54u 289 W) Leptodeirini Leptodeira annulata Throughout the year Throughout the year Southeastern and Central Brazil This work (11u 479 N, 23u 359 S, 39u 439 E, 56u 059 W) Leptodeira maculata Spring–Autumn Spring–Autumn SW Mexico (26u 009 N, 16u 009 S, 98u 009 E, Goldberg, 2004a 109u 009 W) Leptodeira punctata — Spring–Summer W Me´xico (26u 009 N, 21u 009 S, 103u 009 E, Goldberg, 2004a 109u 009 W) 178 HERPETOLOGICA [Vol. 64, No. 2 length of both sexes, duration of vitellogene- Hypsiglena torquata deserticola: Colubridae, in south- sis, egg-carrying period, duration of the western Idaho. Southwestern Naturalist 31:55–64. DOAN, T. M., AND W. A. ARRIAGA. 1999. Imantodes complete reproductive cycle, and clutch size. cenchoa. Aggregation. Herpetological Review 30:102. However, tribes differ in the timing of DUELLMAN, W. E. 1958. A monographic study of the reproductive cycles in females and, apparent- colubrid snake genus Leptodeira. Bulletin of the ly, in the duration of sperm production in American Museum of Natural History 114:1–152. FERRAREZZI, H. 1994. Uma sinopse dos geˆneros e males. Thus, reproduction as a whole seems to classificaçaõ das Serpentes (Squamata): II. Famı´lia have changed relatively little during the Colubridae. Pp. 81–91. In L. B. Nascimento, A. T. history of the dipsadines, as already observed Bernardes, and G. A. Cotta (Eds.), Herpetologia no in other monophyletic lineages of Neotropical Brasil, Volume 1. Puc-MG, Fundaçaõ Biodiversitas e snakes, e.g., the genera Bothrops (Almeida- Fundaçaõ Ezequiel Dias, Belo Horizonte, Minas Gerais, Brazil. Santos and Salomaõ, 2002) and Micrurus FITCH, H. S. 1982. Reproductive cycles in tropical reptiles. (Almeida-Santos et al., 2006). Occasional Papers of the Museum of Natural History of Kansas 96:1–53. Acknowledgments.—We thank S. Cechin (ZUFSM), M. FOWLER, I. R., AND M. G. SALOMA˜ O. 1994. A study of sexual Di-Bernardo (MCP), F. L. Franco (IB), J. C. Moura Leite dimorphism in six species from the colubrid snake (MHNCI) and I. Sazima (ZUEC), for permission to genus Philodryas. The Snake 26:117–122. analyze specimens under their care and Valdir Germano GOLDBERG, S. R. 2001. Reproduction in the night snake, (IB) for help in the laboratory. S. Goldberg helped with Hypsiglena torquata (Serpentes: Colubridae), from literature, B. Phillips and M. Crossland reviewed the text Arizona. Texas Journal of Science 53:107–114. and made important comments. We also thank two GOLDBERG, S. R. 2004a. Notes on reproduction in the anonymous referees for helpful comments and sugges- southwestern cat-eyed snake, Leptodeira maculata, and tions. CNPq provided fellowships to MM, OAVM and MC western cat-eyed snake, Leptodeira punctata (Ser- and FAPESP provided fellowships to JLM and LP. This pentes: Colubridae), from Mexico. Southwestern Nat- study was partly funded by FAPESP. uralist 49:409–412. GOLDBERG, S. R. 2004b. Reproduction in the coffee snake, LITERATURE CITED Ninia maculata (Serpentes: Colubridae), from Costa Rica. Texas Journal of Science 56:81–84. ALMEIDA-SANTOS, S. M., AND M. G. SALOMA˜ O. 2002. GREENE, H. W. 1997. Snakes. The Evolution of Mystery Reproduction in Neotropical pitvipers, with emphasis in Nature. University of California Press, Berkeley, on species of the genus Bothrops. Pp. 445–462. In California, U.S.A. G. W. Schuett, M. E. Douglas, M. Ho¨ggren, and H. W. HARTMANN, P. A., AND O. A. V. MARQUES. 2005. Diet and Greene, H. W (Eds.), Biology of the Vipers. Eagle habitat use of two sympatric species of Philodryas Mountain Publishing, Eagle Mountain, Utah, U.S.A. (Colubridae), in south Brazil. Amphibia-Reptilia ALMEIDA-SANTOS, S. M., L. PIZZATTO, AND O. A. V. 26:25–31. ARQUES M . 2006. Intra–sex synchrony and inter–sex HARTMANN, M. T., M. L. DEL GRANDE,M.J.C.GONDIM, coordination in the reproductive timing of the coral M. C. MENDES, AND O. A. V. MARQUES. 2002. snake Micrurus corallinus (Elapidae) in Brazil. Herpe- Reproduction and activity of the snail-eating snake, tological Journal 16:371–376. Dipsas albifrons (Colubridae), in the southern Atlantic ALVES, F. Q., A. J. S. ARGOˆ LO, AND J. JIM. 2005. Biologia Forest in Brazil. Studies on Neotropical Fauna reprodutiva de Dipsas neivai Amaral e D. catesby Environment 37:111–114. (Sentzen) (Serpentes, Colubridae) no Sudeste da Bahia, KING, R. B. 1989. Sexual dimorphism in tail length: Sexual Brasil. Revista Brasileira de Zoologia 22:573–579. selection, natural selection, or morphological con- BALESTRIN, R. L., AND M. DI-BERNARDO. 2005. Reproduc- straint? Biological Journal of Linnean Society tive biology of Atractus reticulatus (Boulenger 1885) 38:133–154. (Serpentes, Colubridae) in southern Brazil. Herpeto- KOFRON, C. P. 1983. Female reproductive cycle of the logical Journal 15:195–199. Neotropical snail-eating snake Sibon sanniola in BROWN, G. P., AND R. SHINE. 2006. Why do most tropical Northern Yucatan, Mexico. Copeia 1983:963–969. animals reproduce seasonally? Testing hypotheses on LILLYWHITE, H. B., AND R. W. HENDERSON. 1993. an Australian snake. Ecology 87:133–143. Behavioral and functional ecology of arboreal snakes. CADLE, J. E. 1984. Molecular systematics of Neotropical Pp. 1–48. In R. A. Seigel and J. T. Collins (Eds.), xenodontine snakes: I. South American xenodontines. Snakes: Ecology & Behavior. McGraw-Hill, New York, Herpetologica 40:8–20. New York, U.S.A. CADLE,J.E.,AND H. W. GREENE. 1993. Phylogenetic patterns, MARQUES, O. A. V. 1996. Biologia Reprodutiva de biogeography, and the ecological structure of neotropical Erythrolamprus aesculapii Linnaeus (Colubridae), no snake assemblages. Pp. 281–293. In R. E. Ricklefs and D. Sudeste do Brasil. Revista Brasileira de Zoologia Schluter (Eds.), Species Diversity in Ecological Commu- 13:747–753. nities. Historical and Geographical Perspectives. Univer- MARQUES, O. A. V., F. STENDER-OLIVEIRA,R.J.SAWAYA, sity of Chicago Press, Chicago, Illinois, U.S.A. AND F. G. R. FRANÇA. 2006. Ecology of the colubrid DILLER, L. V., AND R. L. WALLACE. 1986. Aspects of the snake Pseudablabes agassizii in south-eastern South life-history and ecology of the desert night snake, America. Herpetological Journal 16:37–45. June 2008] HERPETOLOGICA 179

MARTINS, M. 1996. Defensive tactics in lizards and snakes: bridae) in Costa Rica. Revista de Biologia Tropical The potential contribution of the neotropical fauna. 41:295–297. Pp. 185–199. In Anais do XIV Encontro Anual de SEIGEL, R. A., AND N. B. FORD. 1987. Reproductive Etologia. Sociedade Brasileira de Etologia, Uberlaˆndia, Ecology. Pp. 210–252. In R. A. Seigel, J. T. Collins, and Minas Gerais, Brazil. S. S. Novak (Eds.), Snakes: Ecology & Behavior. MARTINS, M., AND M. E. OLIVEIRA. 1999. Natural history of McGraw-Hill Inc., New York, New York, U.S.A. snakes in forests in the Manaus region, Central SEVER, D. M., R. A. STEVENS,T.J.RYAN, AND W. C. Amazonia, Brazil. Herpetological Natural History HAMLETT. 2002. Ultrastructure of the Reproductive 6:78–150. System of the Black Swamp Snake (Seminatrix pygaea). MARTINS, M., M. S. ARAU´ JO,R.J.SAWAYA, AND R. NUNES. III. Sexual Segment of the Male Kidney. Journal of 2001. Diversity and evolution of macrohabitat use, body Morphology 252:238–254. size and morphology in a monophyletic group of SHINE, R. 1977. Reproduction in Australian Elapid Neotropical pitvipers (Bothrops). Journal of Zoology Snakes. I. Testicular cycles and mating seasons. 254:529–538. Australian Journal of Zoology 25:647–653. MARTINS, M., O. A. V. MARQUES, AND I. SAZIMA. 2002. SHINE, R. 1978. Growth rates and sexual maturation in six Ecological and phylogenetic correlates of feeding habits species of Australian elapid snakes. Herpetologica 34:73–79. in Neotropical pitvipers (Genus Bothrops). SHINE, R. 1980. Comparative ecology of three Australian Pp. 307–328. In G. W. Schuett, M. Ho¨ggren, M. E. snake species of the genus Cacophis (Serpentes, Douglas, and H. W. Greene (Eds.), Biology of the Colubridae). Copeia 1980:831–838. Vipers. Eagle Mountain Publishing, Eagle Mountain, SHINE, R. 1994. Sexual size dimorphism in snakes Utah, U.S.A. revisited. Copeia 1994:326–346. PIZZATTO, L., AND O. A. V. MARQUES. 2002. Reproductive SLIP, D. J., AND R. SHINE. 1988. The reproductive biology biology of the false coral snake Oxyrhopus guibei and mating system of diamond pythons, Morelia spilota (Serpentes: Colubridae) from southeastern Brazil. (Serpentes: Boidae). Herpetologica 44:396–404. Amphibia-Reptilia 23:495–504. TRIVERS, R. L. 1972. Parental investment and sexual PIZZATTO, L., AND O. A. V. MARQUES. 2006. Interpopula- selection. Pp. 136–179. In B. Campbell (Ed.), Sexual tonal variation in reproductive cycles and activity of the Selection and the Descent of Man. Aldine-Atherton, water snake Liophis miliaris (Colubridae) in Brazil. Chicago, Illinois, U.S.A. Herpetological Journal 16:353–362. VIDAL, N., S. G. KINDL,A.WONG, AND S. B. HEDGES. 2000. PIZZATTO, L., AND O. A. V. MARQUES. 2007. Reproductive Phylogenetic relationships of Xenodontine snakes ecology of Boine snakes with emphasis on Brazilian inferred from 12S and 16S ribosomal RNA sequences. species and a comparison to pythons. South American Molecular Phylogenetics and Evolution 14:389–402. Journal of Herpetology 2:107–122. VITT, L. J. 1987. Communities. Pp. 335–365. In R. A. PIZZATTO, L., S. M. ALMEIDA-SANTOS, AND O. A. V. Seigel, J. T. Collins, and S. S. Novak (Eds.), Snakes: MARQUES. 2007a. Biologia reprodutiva de serpentes Ecology & Behavior. McGraw-Hill Inc., New York, Brasileiras. Pp. 201–221. In L. B. Nascimento and M. E. New York, U.S.A. Oliveira (Eds.), Herpetologia no Brasil II. Sociedade VITT, L. J. 1996. Ecological observations on the tropical Brasileira de Herpetologia, Belo Horizonte, Minas colubrid snake Leptodeira annulata. Herpetological Gerais, Brazil. Natural History 4:69–76. PIZZATTO, L., S. M. ALMEIDA-SANTOS, AND R. SHINE. 2007b. VOLSØE, H. 1944. Seasonal variation of the male Life history adaptations to arboreality in snakes. reproductive organs of Vipera berus (L.). Spolia Ecology 88:359–366. Zoologia Museum Hauniensis 5:1–157. PIZZATTO, L., R. S. JORDA˜ O, AND O. A. V. MARQUES. 2008. YOKOYAMA, F., AND H. YOSHIDA. 1993. The reproductive Overview of reproductive strategies in Xenodontini cycle of the male habu, Trimeresurus flavoviridis. The (Serpentes: Colubridae: Xenodontinae) with new data Snake 25:55–62. for Xenodon neuwiedii and Waglerophis merremii. WALLACH, V. 1995. Revalidation of the genus Tropido- Journal of Herpetology 42:153–162. dipsas Gunther, with notes on the Dipsadini and RODRI´GUEZ-ROBLES, J. A., D. G. MULCAHY, AND H. W. Nothopsini (Serpentes: Colubridae). Journal of Herpe- GREENE. 1999. Feeding ecology of the desert night- tology 29:476–481. snake, Hypsiglena torquata (Colubridae). Copeia ZAHER, H. 1999. Hemipenial morphology of the South- 1999:93–100. American xenodontines snakes, with a proposal for a RUNQUIST, E. M. 2002. Natural history of the night snake, monophyletic xenodontinae and reappraisal of colu- Hypsiglena torquata, in Kansas. Journal of Kansas broid hemipenis. Bulletin of the American Museum of Herpetology 4:16–20. Natural History 260:1–168. SANTOS, X., G. A. LLORENTE,M.FERICHE,J.M.PLEGUE- ZAR, J. H. 1999. Biostatistical Analysis, 4th Ed. Prentice ZUELOS,F.CASALS, AND A. DE SOSTOA. 2005. Food Hall, Upper Saddler River, New Jersey, U.S.A. availability induces geographic variation in reproductive ZUG, G. R., S. B. HEDGES, AND S. SUNKEL. 1979. Variation in timing of an aquatic oviparus snake (Natrix maura). reproductive parameters of three Neotropical snakes, Amphibia-Reptilia 26:183–191. Coniophanes fissidens, Dipsas catesbyi,andImantodes SANTOS-COSTA, M. C., AND A. L. C. PRUDENTE. 2005. cenchoa. Smithsonian Contributions to Zoology 300:1–18. Imantodes cenchoa (Chunck-headed snake). Mating. Herpetological Review 36:324. SASA, M. 1993. Distribution and reproduction of the grey .Accepted: 15 February 2008 earth snake Geophis brachycephalus (Serpentes: Colu- .Associate Editor: Brad Moon