sign in sign up
<<
Home , Amphiesmoides, Azemiops, Calamaria, Cerberus (snake), Chinese kukri snake, Emydocephalus

Herpetology Notes, volume 7: 771-777 (2014) (published online on 21 December 2014)

New records of (: Serpentes) from Son La Province,

Anh Van Pham1,2, Son Lan Hung Nguyen2 and Truong Quang Nguyen3,*

Abstract. We report seven new records of from Son La Province, northwestern Vietnam on the basis of a new collection from Copia Nature Reserve (Thuan Chau District) and Son La City, comprising six species of (Cyclophiops multicinctus, Gonyosoma frenatum, G. prasinum, Liopeltis frenatus, catenatus, and O. chinensis) and one species of Pseudoxenodontidae ( macrops). Our findings bring the species number of snakes to 51 in Son La Province.

Keywords. Colubridae, Pseudoxenodontidae, distribution, , Copia Nature Reserve, Son La City.

Introduction Murphy, Voris, Murthy, Traub and Cumberbatch, 2012; Oligodon nagao David, Nguyen, Nguyen, Jiang, In the recent checklist of the herpetofauna of Vietnam, Chen, Teynié and Ziegler, 2012; Oligodon cattienensis Nguyen, Ho and Nguyen (2009) listed 192 species of Vassilieva, Geissler, Galoyan, Poyarkov, Van Devender snakes. Since then one new (Colubroelaps Orlov, and Böhme, 2013; and kharini Orlov, Ryabov Kharin, Ananjeva, Nguyen and Nguyen, 2009), 13 new & Nguyen, 2013. In addition, nine new country records species and one new subspecies of snakes have been of snakes have reported from the country, comprising described in Vietnam, viz. Calamaria gialaiensis Ziegler, two species of Colubridae, one species of , Nguyen and Nguyen, 2008; Calamaria abramovi and six species of (Vogel et al., 2009; Nguyen Orlov, 2009; Colubroelaps nguyenvansangi Orlov, et al., 2010; Rasmussen et al., 2011; Murphy et al., Kharin, Ananjeva, Nguyen and Nguyen, 2009; Lycodon 2012a). ruhstrati abditus Vogel, David, Pauwels, Sumonth, In Son La Province, Nguyen, Ho and Nguyen (2009) Norval, Hendrix, Vu and Ziegler, 2009; Protobothrops documented a total of 38 species of snakes. Pham et trungkhanhensis Orlov, Ryabov and Nguyen, 2009; al. (2013) recently recorded five species of colubrids Calamaria concolor Orlov, Nguyen, Nguyen, Ananjeva and one species of viper for the first time from Son La and Ho, 2010, Calamaria sangi Nguyen, Koch and Province. In this paper, we report seven new records of Ziegler, 2010, Emydocephalus szczerbaki Dotsenko, snakes for Son La Province based on newly collected 2010; Opisthotropis cucae David, Pham, Nguyen and materials from Copia Nature Reserve (Thuan Chau Ziegler, 2011; Trimeresurus rubeus (Malhotra, Thorpe, District) and Son La City. Mrinalini and Stuart, 2011); mereljcoxi Material and Methods Field surveys were conducted in the Copia Nature Reserve (NR), Thuan Chau District and on the outskirts 1 Faculty of Biology and Chemistry, Tay Bac University, Quyet of Son La City, Son La Province, northwestern Vietnam Tam Ward, Son La City, Son La Province, Vietnam. E-mail: (Fig. 1) by Anh Van Pham, Tan Van Nguyen, Ngoc Thi [email protected] Bich Nguyen, Men Thi Nguyen, and Hoang Van Tu 2 Faculty of Biology, Hanoi National University of Education, (hereafter AVP et al.) between June 2013 and August 136 Xuan Thuy Street, Cau Giay District, Hanoi, Vietnam. 2014. Specimens were collected by hand or snake E-mail: [email protected]­ 3 Institute of Ecology and Biological Resources, Vietnam hook between 9:00–23:00. After taking photographs, Academy of Science and Technology, 18 Hoang Quoc Viet specimens were anaesthetized in a closed vessel with Road, Hanoi, Vietnam. E-mail: [email protected] a piece of cotton wool containing ethyl acetate, fixed in * Corresponding author 85% ethanol and subsequently stored in 70% ethanol. 772 Anh Van Pham et al.

Bom Commune, Copia NR, Thuan Chau District, Son La Province (21°23.460’N, 103°37.732’E, elevation 1260 m a.s.l.). Morphological characters. Body cylindrical; head moderately distinct from neck; eye large, pupil round; rostral as broad as high, partly visible from above; internasal not in contact with loreal; prefrontal as long as half of frontal; parietals longer than wide; nasal undivided; loreal 1/1, not contact with orbit; preocular 1/1; postoculars 2/2, bodering anterior temporals; anterior temporal 1/1, posterior temporals 2/2; subpralabials 7/7, fourth and fifth touching the eye, sixth largest; infralabials 6/6, first to fourth bordering chin shields; dorsal scale rows 15–15–15, smooth; ventrals 180; cloacal scale paired; subcaudals 93, paired. Coloration in preservative. Dorsal surface green anteriorly, grey posteriorly, with whitish cross–bars on the posterior half of the body and tail; belly whitish green anteriorly, grey posteriorly (determination after Smith 1943). Ecological notes. The adult female was collected at 20:00 on tree branch, ca. 1.2 m above on the forest floor, near a stream. The surrounding habitat was evergreen secondary forest. Distribution. In Vietnam, this species has been recorded from Lai Chau and Lao Cai provinces in the Figure 1. Map showing the survey site (black square) in Son North southwards to Kon Tum and Lam Dong provinces La Province, northwestern Vietnam. (Nguyen et al., 2009). Elsewhere, this species is known from and (Nguyen et al., 2009). Remarks. The specimen from Son La differs from the description of Smith (1943) in having more ventrals (180 versus 164–177). Specimens were deposited in the collections of the Faculty of Biology and Chemistry, Tay Bac University (TBU), Son La Province, Vietnam. Abbreviation are as follows: SVL (snout-vent length): from tip of snout to anterior margin of cloaca; TaL (Tail length): from posterior margin of cloaca to tip of tail; a.s.l.: above sea level. Bilateral scale counts were given as left/right.

Results Taxonomic accounts Family Colubridae Cyclophiops multicinctus (Roux, 1907) Many-banded Green Snake / Ran nhieu dai (Fig. 2) Specimen examined (n = 1). One adult female TBU PAR.183 (SVL 845 mm, TaL 260 mm) collected by Figure 2. Cyclophiops multicinctus (TBU PAR.183, adult AVP et al., 19 June 2014, near Huoi Pu Village, Chieng female) from Son La Province. New records of snakes from Son La Province, Vietnam 773

Figure 3. Gonyosoma frenatum (TBU PAR.154, adult female) Figure 4. Gonyosoma prasinum (TBU PAR.86, adult female) from Son La Province, Vietnam. from Son La Province, Vietnam.

Gonyosoma frenatum (Gray, 1853) The surrounding habitat was evergreen secondary Khasi / Ran soc ma (Fig. 3) forest. Distribution. In Vietnam, this species has been recorded Specimens examined (n = 3). Three specimens from Lao Cai, Lang Son, Vinh Phuc and Quang Binh collected by AVP et al. near Nong Vai Village provinces (Nguyen et al., 2009). This species is also (21°19.953’N, 103°35.283’E, elevation 1470 m a.s.l.), known from China and (Nguyen et al., 2009). Co Ma Commune, Copia NR, Thuan Chau District, Son La Province: TBU PAR.114 (SVL: 234 mm, TaL: Gonyosoma prasinum (Blyth, 1854) 90 mm), subadult female, 17 August 2013 and TBU Green Bush Rat Snake / Ran soc xanh (Fig. 4) PAR.133 (SVL: 275 mm, TaL: 117 mm), subadult female, 15 September 2013; TBU PAR.154 (SVL: 860 Specimens examined (n = 3). Three specimens mm, TaL: 298+ mm, tail tip lost), adult female, 17 April collected by AVP et al. in Copia NR, Thuan Chau 2014. Distric, Son La Province: TBU PAR.86 (SVL: 613 Morphological characters. Body subcylindrical; mm, TaL: 216 mm), adult female, 25 July 2013, near head distinguished from neck, rather flattened; snout Hua Ty Village, Co Ma Commune (21°20.923’N, elongate; pupil rounded; rostral broader than high, partly 103°34.834’E, elevation 1400 m a.s.l.); TBU PAR.135 visible from above; internasals wider than long, as long (SVL: 676 mm, TaL: 253 mm), adult male, 12 October as prefrontal; prefrontal approximately half length of 2013, near Hua Ty B Village, Chieng Bom Commune frontal, in contact with second to third supralabials; (21°22.952’N, 103°37.986’E, elevation 1370 m a.s.l.), frontal hexagonal; parietals longer than wide; nasal and TBU PAR.182 (SVL: 773 mm, TaL: 267 mm), paired; loreal absent; supralabials 9/9, fourth to sixth adult male, 10 May 2014, near Nong Vai Village, Co touching the eye, eighth largest; infralabials 9/9 or Ma Commune (21°19.510’N, 103°35.387’E, elevation 10/10, first to fifth bordering chin shields; preocular 1/1; 1510 m a.s.l.). postoculars 2/2, bodering anterior temporals; anterior Morphological characters. Body subcylindrical; temporals 2/2, posterior temporals 3/3; dorsal scale head distinguished from neck, rather flattened; snout rows 19–19–15, smooth; ventrals 205–206; cloacal elongate; pupil rounded; rostral broader than high, partly scale paired; subcaudals 133–143, paired. visible from above; internasals as wide as long, not in Coloration in preservative. Dorsal surface green or contact with loreal; prefrontal as long as half length of greenish grey; lateral head with a black stripe, from frontal; frontal pentagonal; parietals longer than wide; nasal across the eye to the neck; chin and belly white nasal paired; loreal 1/1; supralabials 9/9, fourth to sixth (determination after Smith, 1943). entering orbit, eighth largest; infralabials 10/10, first to Ecological notes. The specimens were collected fifth bordering chin shields; preocular 1/1; postoculars between 9:00 and 10:00 while moving across the road. 2/2, bodering anterior temporals; anterior temporals 774 Anh Van Pham et al.

Figure 5. Liopeltis frenatus (TBU PAR.109, adult male) from Figure 6. Oligodon catenatus (TBU PAR.100, adult male) Son La Province, Vietnam. from Son La Province, Vietnam.

2/2, posterior temporals 2/3; dorsal scale rows 19–19– rostral distinctly broader than high, partly visible from 15, keeled; ventrals 193–198 in males, 193 in female; above; internasals broader than long, not in contact cloacal scale paired; subcaudals 102–103 in males, 96 with loreal; prefrontal less than half length of frontal; in the female, paired. parietals longer than wide; nasal undivided; loreal 1/1, Coloration in preservative. Dorsal surface green; not contact with orbit; preocular 1/1; postoculars 2/2, upper lip and lower parts greenish white, chin and belly bodering anterior temporals; anterior temporal 1/1, greenish (determination after Smith, 1943). posterior temporals 2/2; subpralabials 7/7, third and Ecological notes. Two adult males were collected fourth entering orbit, sixth largest; infralabials 8/8, first between 8:00 and 9:00 while moving across the road; to fourth bordering chin shields; dorsal scale rows 15– one adult female were collected at ca. 21:00 on the tree, 15–15, smooth; ventrals 149 in the male and 144 in the 1 m above the forest floor. The surrounding habitat was female; cloacal scale paired; subcaudals 100 in the male evergreen secondary forest. and 94 in the female, paired. Distribution. In Vietnam, this species has been Coloration in preservative. Dorsal surface yellowish recorded from Lao Cai, Bac Kan, Thai Nguyen, Vinh brown with longitudinal lines on the anterior half of the Phuc, Nghe An, Quang Binh, and Gia Lai provinces body; lateral side of head with a broad black stripe, from (Nguyen et al., 2009). Elsewhere, this species is known behind the eye to the neck; upper jaw, chin and belly from China, India, , , and white (determination after Smith, 1943). Laos (Nguyen et al., 2009). Ecological notes. The adult male was collected at ca. 9:00 while moving across the road and the adult Liopeltis frenatus (Günther, 1858) female was collected at ca. 16:00 on forest path. The Frenated Ringneck / Ran dai ma (Fig. 5) surrounding habitat was evergreen secondary forest. Distribution. Liopeltis frenatus is a rare snake species Specimens examined (n = 2). Two specimens collected in Vietnam. This species has been recorded from Lao by AVP et al. in Copia NR, Thuan Chau District, Son La Cai, Quang Binh, Da Nang, Gia Lai and Dong Nai Province: TBU PAR.109 (SVL 335 mm, TaL 160 mm), provinces (Orlov et al., 2003; Nguyen et al., 2009). adult male, 16 August 2013, near Hua Ty Village, Co Elsewhere, this species is known from China, India, Ma Commune (21°20.234’N, 103°35.194’E, elevation Myanmar, and Laos (Nguyen et al., 2009). 1460 m a.s.l.) and TBU PAR.116 (SVL 255 mm, TaL 116 mm), adult female, 29 August 2013, near Hua Ty Oligodon catenatus (Blyth, 1854) B Village, Chieng Bom (21°21.667’N, 103°36.529’E, Kukri Snake / Ran khiem a-sam (Fig. 6) elevation 1510 m a.s.l.). Morphological characters. Body cylindrical; head Specimens examined (n = 4). Four specimens collected moderately distinct from neck; eye large, pupil round; by AVP et al. in Co Ma Commune, Copia NR, Thuan New records of snakes from Son La Province, Vietnam 775

Ecological notes. Two adult males were collected between 8:00 and 9:00 while moving across the road and two adult females were collected between 9:00 and 9:30 on forest path. The surrounding habitat was evergreen secondary forest. Distribution. Oligodon catenatus is a poorly known species in Vietnam. This species has been recorded from Lao Cai and Vinh Phuc provinces (Nguyen et al., 2009). Elsewhere, this species is known from China, India, Myanmar and Cambodia (Nguyen et al., 2009). Remarks. O. catenatus is morphologically similar to O. eberharti but they can be distinguished from each Figure 7. Oligodon chinensis (TBU PAR.191, adult female) other by the presence of a loreal in the latter. from Son La Province, Vietnam.

Oligodon chinensis (Günther, 1888) Chinese Kukri Snake / Ran khiem trung quoc (Fig. 7) Specimen examined (n = 1). One adult female TBU Chau District, Son La Province: TBU PAR.100 (SVL PAR.191 (SVL 580 mm, TaL 103 mm) collected 525 mm, TaL 75 mm), adult male, 15 August 2013, by AVP et al., 1 August 2014, near Khoang Village, and TBU PAR.117 (SVL 517 mm, TaL 61.5 mm), Chieng Ngan Commune, Son La City, Son La Province adult female, 30 August 2013, near Nong Vai Village (21°18.540’N, 103°56.578’E, elevation 690 m a.s.l.). (21°19.675’N, 103°33.969’E, elevation 1570 m a.s.l.); Morphological characters. Body cylindrical; head TBU PAR 120 (SVL 483 mm, TaL 55 mm), adult moderately distinct from neck; eye large, pupil round; female, 13 September 2013, and TBU PAR.172 (SVL rostral as broad as high, visible from above; internasals 527 mm, TaL 72 mm), adult male, 19 April 2014, near as broad as long; prefrontal about one-third of frontal; Co Ma Village (21°22.005’N, 103°29.596’E, elevation parietals as long as wide; nasal undivided; loreal 1/1; 1360 m a.s.l.). preocular 1/1; postoculars 1/1, bodering anterior Morphological characters. Body cylindrical; head temporals; anterior temporal 1/1; posterior temporals indistinct from neck; eye small, pupil round; rostral 2/2; subpralabials 7/8, third and fourth or fourth and distinctly broader than high, visible from above; fifth touching the eye, fifth or sixth largest; infralabials internasals absent; prefrontal shorter than frontal, in 7/7, first to fourth bordering chin shields; dorsal scale contact with the second labial; parietals longer than rows 17–17–15, smooth; ventrals 193; cloacal scale wide; nasal undivided; loreal absent; preocular 1/1; undivided; subcaudals 50, paired. postoculars 1/1, bodering anterior temporals; anterior Coloration in preservative. Dorsal surface of head temporal 1/1; posterior temporals 2/2; supralabials and body yellowish brown with dark brown blotches, 6/6, third and fourth touching the eye, fifth largest; edged in black; dorsal head with two dark marking in infralabials 6/6, first to fourth bordering chin shields; ˄-shape, edged in black: a narrow one between the eyes dorsal scale rows 13–13–13, smooth; ventrals 179– and another one on the nape; venter cream anteriorly 184 in males and 190–193 in females; cloacal scale and pinkish posteriorly with black square spots undivided; subcaudals 31–36 in males and 30–35 in (determination after Smith, 1943; David et al., 2008). females, paired. Ecological notes. The adult female was collected at ca. Coloration in life. Dorsal head dark brown, dorsal 20:30 while moving on the forest floor. The surrounding surface of body greyish brown with an yellow vertebral habitat was secondary karst forest. stripe formed by a concatenation of lozenge-shaped Distribution. In Vietnam, this is a widespread species spots, edged in black, from the neck to the end of tail; known from Lao Cai and Lang Son in the North lateral side of head with three yellow oblique streaks: southwards to Quang Binh and Gia Lai provinces one in loreal region, one behind the eye and one on neck; venter red, each ventral with a black square spot (Nguyen et al., 2009). This species is also known from at the outer end and a white spot (determination after China (Nguyen et al., 2009). Smith, 1943; Vassilieva et al., 2013). 776 Anh Van Pham et al.

Coloration in preservative. Dorsal surface brownish grey or brownish red with dark or reddish spots or short greyish cross-bars; chin and venter yellowish cream, with large black spots anteriorly (determination after Smith, 1943). Ecological notes. Two adult females were collected between 9:00 and 10:00 on the forest path; one adult female was collected at ca. 9:00 while moving across the road and another male was collected at ca. 20:00 on forest path, near a slow flowing stream. The surrounding habitat was evergreen secondary forest. Distribution. In Vietnam, this species has been recorded from Lai Chau, Lao Cai, Vinh Phuc, Nghe An, Ha Tinh, Quang Binh, Da Nang and Lam Dong Figure 8. (TBU PAR.119, adult male) from Son La Province, Vietnam. provinces (Nguyen et al., 2009). This species is also known from India, , China, Myanmar, Malaysia, Thailand and Laos (Nguyen et al., 2009).

Discussion Family Pseudoxenodontiae Son La Province is located in the northwestern region, Pseudoxenodon macrops (Blyth, 1854) one of four biodiversity centres of Vietnam (Tordoff et Big-eyed Bamboo Snake / Ran ho xien mat to (Fig. 8) al., 2004). Sterling et al. (2006) indicated that a wild range of elevations and the complexity of landforms Specimens examined (n = 4). Four specimens collected have given the northwestern region of Vietnam a by AVP et al. in Co Ma Commune, Copia NR, Thuan great diversity of natural habitats and a high level of Chau District, Son La Province: three adult females: biodiversity potential. For instance, north of the Son TBU PAR.71 (SVL: 520 mm, TaL: 116 mm), 9 June La Province, the Hoang Lien National Park in Lao 2013; TBU PAR.89 (SVL: 480 mm, TaL: 105 mm), Cai Province harbours a total of 57 species of snakes 1 August 2013, near Hua Ty Village (21°20.497’N, (Nguyen et al., 2009). The new records bring the total 103°35.215’E, elevation 1470 m a.s.l.); TBU PAR.103 number of snake species to 51 in Son La Province and (SVL: 540 mm, TaL: 116 mm), 15 August 2013, near Pha it is expected that further new records of and Khuong Village (21°21.009’N, 103°32.467’E, elevation amphibians will be made from this province in further 1370 m a.s.l.); and one adult male TBU PAR.119 (SVL: studies. 555 mm, TaL: 135 mm), 2 September 2013, near Pha Khuong Village (21°21.296’N, 103°32.145’E, elevation 1360 m a.s.l.). Acknowledgements. We are grateful to the directorate of Morphological characters. Body cylindrical; head Copia Nature Reserve for support of our field work. We thank T. V. Nguyen, N. B. T. Nguyen, M. T. Nguyen, H. V. Tu (Tay distinct from neck; snout elongate; eye large, pupil Bac University) and M. A. Lau, T. A. Sung (Son La) for their rounded; rostral as broad as high, partly visible from assistance in the field. We thank T. Ziegler (Cologne) and two above; internasals as wide as long, not in contact with anonymous reviewers for their helpful comments. Many thanks loreal; prefrontal about a half length of frontal; frontal to E. Sterling (New York) and K. Koy (Berkeley) for providing pentagonal; parietals longer than wide; nasal paired; the map. Field equipment was supported by the Ideal Wild to A. loreal 1/1; supralabials 8/8, fourth to fifth entering orbit, V. Pham. Research of T. Q. Nguyen is funded by the National 7 largest; infralabials 10/10, first to fifth or first to fourth Geographic Society (Grant No. 9492–14) and the Alexander von Humboldt Foundation (VIE 114344). bordering chin shields; preocular 1/1; postoculars 3/3, bordering anterior temporals; anterior temporals 2/2; posterior temporals 2/2; dorsal scale rows 19–17–15, References keeled; ventrals 165 in the male, 155–168 in females; David, P., Vogel, G., Pauwels, O.S.G. (2008): A new species of the cloacal scale paired; subcaudals 66 in the male, 60–62 genus Oligodon Fitzinger, 1826 Squamata: Colubridae) from in females, paired. southern Vietnam and Cambodia. Zootaxa 1939: 19-37 New records of snakes from Son La Province, Vietnam 777

Dotsenko, I.B. (2010): Emydocephalus szczerbaki sp. n. (Serpentes, Smith, M.A. (1943): The fauna of British India, Ceylon and Burma, Elapidae, Hydrophiinae) - a new species of the Turtleheaded including the whole of the Indo-Chinese Subregion. Reptilia and genus from Vietnam [in Russian]. Zbirnik prats’ Amphibia. Vol. III. Serpentes. Taylor and Francis (London). zoologichnogo museyu 41: 128-138. Sterling, E.J., Hurley, M.H., Le, D.M. (2006): Vietnam: A Natural Murphy, J.C., Voris, H.K., Karns, D.R. (2012): The dog-faced History. Yale University Press, New Haven, Connecticut. water snakes, a revision of the genus Cuvier, Tordoff, A.W., Tran, B.Q., Nguyen, T.D., Le, H.M. (eds) (2004): (Squamata, Serpentes, Homalopsidae), with the description of Sourcebook of existing and proposed protected areas in Vietnam. a new species. Zootaxa 3484: 1-34. Birdlife International in Indochina and Ministry of Agriculture Nguyen, V.S., Ho, T.C., Nguyen, Q.T. (2009): Herpetofauna of and Rural Development, second edition, Hanoi. Vietnam. Edition Chimaira, Frankfurt am Main. Vassilieva, A.B., Geissler, P., Galoyan, E.A., Poyarkov, Jr., N.A., Nguyen, Q.T., David, P., Tran, T.T., Luu, Q.V., Le, K.Q., Ziegler, Van Devender, R.W., Böhme, W. (2013): A new species of T. (2010): Amphiesmoides ornaticeps (Werner, 1924), an Kukri Snake (Oligodon Fitzinger, 1826; Squamata: Colubridae) addition to the snake fauna of Vietnam, with a redescription from the Cat Tien National Park, southern Vietnam. Zootaxa and comments on the genus Amphiesmoides Malnate, 1961 3702: 233-246. (Squamata: Natricidae). Revue suisse de Zoologie 117: 45-56. Vogel, G., David, P., Pauwels, O.S.G., Sumontha, M., Norval, G., Nguyen, Q.T., Koch, A., Ziegler, T. (2010 “2009”): A new species Hendrix, R., Vu, N.T., Ziegler, T. (2009). A revision of Lycodon of reed snake, Calamaria Boie (Squamata: Colubridae), from ruhstrati (Fischer, 1886) auctorum (Squamata Colubridae), Central Vietnam. Hamadryad 34: 1-8. with the description of a new species from Thailand and a new Pham, V.A., Nguyen, T.B.N., Nguyen, T.M., Nguyen, L.H.S., subspecies from the Asian mainland. Tropical Zoology 22: 131- Nguyen, Q.T. (2013): New records of snakes (Reptilia: 182. Squamata: Serpentes) from Son La Province. In: Proceedings of the fifth National Scientific Conference on Ecological notes and Biological Resources, , p.16-22. Agriculture Publishing House, Hanoi. Rasmussen, A.R., Elmberg, J., Gravlund, P., Ineich, I. (2011): Sea snakes (Serpentes: subfamilies Hydrophiinae and Laticaudinae) in Vietnam: a comprehensive checklist and an updated identification key. Zootaxa 2894: 1-20.

Accepted by Cynthia Prado; Managing Editor: Alessandro Morais