BOLETIM DO MUSEU NACIONAL NOVA SÉRIE RIO DE JANEIRO - BRASIL

Transcription

1 BOLETIM DO MUSEU NACIONAL NOVA SÉRIE RIO DE JANEIRO - BRASIL ISSN X ZOOLOGIA N o DE NOVEMBRO DE 2002 LEPTOGNATHUS LATIFASCIATUS BOULENGER, 1913, A JUNIOR SYNONYM OF DIPSAS POLYLEPIS (BOULENGER, 1912) (SERPENTES, COLUBRIDAE) ( 1 ) (With 3 figures) RONALDO FERNANDES ( 2)(3) DANIEL S. FERNANDES ( 2) (4) PAULO PASSOS ( 2) (5) ABSTRACT: Dipsas polylepis (Boulenger, 1912) was described based on a single specimen from Huancabamba, Peru, and distinguished of the remaining species by showing an abnormally high dorsal scales rows number. This character alone was sufficient to place D. polylepis in its own species group, but the color pattern of D. polylepis is similar to the D. pratti species group. The exam and comparison of the holotypes of D. polylepis and D. latifasciata (Boulenger, 1913), revealed that they are very similar. The differences of coloration are likely the result of ontogenetic change proper of the D. pratti species group. Therefore, based in ours observations, we suggest that D. latifasciata should be placed in the synonymy of D. polylepis. Key words: Serpentes, Colubridae, Dipsas, taxonomy. RESUMO: Leptognathus latifasciatus Boulenger, 1913, um sinônimo júnior de Dipsas polylepis (Boulenger, 1912) (Serpentes, Colubridae) Dipsas polylepis (Boulenger, 1912) foi descrita com base em um único exemplar procedente de Huancabamba, Peru, e distinguido das demais espécies do gênero por apresentar um alto número de fileiras dorsais. Esse caráter foi suficiente para a alocação desta espécie em grupo próprio, mas o padrão de colorido de D. polylepis é similar ao das espécies do grupo D. pratti. O exame e comparação dos holótipos de D. polylepis e D. latifasciata (Boulenger, 1913) revelou que ambos são bastante semelhantes. As diferenças de coloração são provavelmente resultado de mudança ontogenética característica do grupo D. pratti. Portanto, com base em nossas observações, sugerimos que D. latifasciata seja colocada na sinonimia de D. polylepis. Palavras-chave: Serpentes, Colubridae, Dipsas, Taxonomia. INTRODUCTION The gastropod-eating Dipsadinae constitute a monophyletic group of Neotropical snakes (BRONGERSMA, 1958; PETERS, 1960) defined by a series of morphological characters. PETERS (1960) provided the most comprehensive taxonomic revision of these snakes and proposed seven species groups for Dipsas, although he later 1 Received on March 21, Accepted on July 3, Museu Nacional/UFRJ, Departamento de Vertebrados. Quinta da Boa Vista, São Cristóvão, , Rio de Janeiro, RJ, Brasil. 3 Fellow of Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). ronnie@acd.ufrj.br. 4 danfer@acd.ufrj.br. 5 ppassos@mn.ufrj.br.

2 2 R.FERNANDES, D.S.FERNANDES & P.PASSOS conceded that at least one of these, the D. polylepis group, which included all species of Dipsas with more than 15 dorsal scales rows, was artificial (PETERS, 1970). Six species were, at a certain point, associated with the D. polylepis group: D. chaparensis Reynolds & Foster, 1992, D. leucomelas (Werner, 1916), D. longicaudata (Andersson, 1901), D. poecilolepis (Amaral, 1923), D. perijanensis (Aleman, 1953), and D. polylepis (Boulenger, 1912). Of these, DOWNS (1961) transferred D. leucomelas to Tropidodipsas (=Sibon), while HOGE (1964) transferred D. longicaudata to Siphlophis, and FERNANDES, PORTO & CARAMASCHI (1998) synonymized D. poecilolepis with Sibynomorphus ventrimaculatus (Boulenger, 1885). All members of the D. polylepis group are known only from the holotype, with the exception of D. chaparensis, which we believe to be closely related to D. indica (R. Fernandes, unpubl. data). The two remaining species of the group, D. perijanensis and D. polylepis, appear to be aberrant specimens of other species of dipsadine snakes (PETERS, 1970). Considering the suspicious status of the species of this group, we examined the holotypes of Leptognathus polylepis Boulenger, 1912 and compared it with other sympatric species of Dipsas. BOULENGER (1912) described Leptognathus polylepis based on a single specimen from Huancabamba, Peru. He found it distinguishable from other species of Leptognathus (as he identified Dipsas at that time) by the high number of dorsal scales rows. Later, AMARAL (1929) transferred it to the genus Tropidodipsas, without further comment. PETERS (1960), without examining the holotype, placed it back in Dipsas. MATERIAL AND METHODS We examined the holotypes of Leptognathus polylepis and Leptognathus latifasciatus deposited in the Natural History Museum, London (BMNH), as well as comparative material of Dipsas latifrontalis at the Museum of Zoology of the University of Michigan (UMMZ). Usual snake description methodology was used, ventrals being counted following the method of DOWLING (1951). Body measurements were taken with a metallic ruler to the nearmost millimeter. RESULTS The holotype of Leptognathus polylepis (BMNH ) (Figs.1-2), an adult female collected at Huancabamba, Peru, above 1,000m altitude, from the collection of E. Boettger, has: head distinct from body; body with 725mm in snout-vent length, strongly compressed laterally; tail with 241mm; rostral wider than high, visible from above; internasals approximately one-half length of prefrontals, which do not enter the orbit; frontal slightly broader than long; parietals wider than long; nasal divided; head scale counts are as follows: preoculars 1 above loreal that contact the orbit, postoculars 2, temporals 2+2 on the left side and 2+3 on the right side (2+3 on both sides, according to BOULENGER, 1912); supralabials 9, fourth to sixth in contact with the orbit; infralabials 13 in the left side and 12 in the right side, first pair in contact anterior to genials, second pair nearly in contact before genials, seventh being the posteriormost in contact with genials; genials in three pairs. Dorsal scales smooth, with no apical pits; rows in an irregular pattern (16, 17, 18, and 19 rows) due to large number of fusions and divisions; vertebral row not enlarged up to the

3 LEPTOGNATHUS LATIFASCIATUS, A JUNIOR SYNONYM OF DIPSAS POLYLEPIS 3 point of ventral 123, when becomes moderately enlarged, according to the definition of PETERS (1960); 198 ventrals (199 according to BOULENGER, 1912); cloacal single; 94/94 subcaudals. Maxilla with 17 teeth, palatine with 19 teeth, and dentaries with 18 on left side and 20 on the right side, where is broken. Head dark brown, slightly darker than the rest of body, and with white spots in anterior part of loreals, supralabials (more conspicuous in the posterior ones), and gulars; a pale brown, one to two dorsal scales long nuchal collar; body and tail dark brown with 22 dark brown, white bordered, dorsal body blotches, four to five times wider than interspaces, with near parallel edges, fused across vertebral line, and nine more on the tail; venter darker than body, with spots of the same color of interspaces; dorsal blotches extend over belly, often contacting in middle. ]]]]] Fig.1- Dorsal, lateral, and ventral views of the head of the holotype of Leptognathus polylepis Boulenger, 1912 (BMNH ) (ruler equal to 5mm).

4 4 R.FERNANDES, D.S.FERNANDES & P.PASSOS Disregarding the abnormal number of dorsal scales rows, the type of Leptognathus polylepis would be clearly included in the Dipsas pratti species group. Except for the D. polylepis group, which was defined by the high number of dorsal scales rows, PETERS (1960) defined his groups based on coloration. However, the D. pratti group was defined by absence of the color patterns characteristic to the other groups (PETERS, 1960) and presence of an ontogenetic change, in which adults tend to an almost complete darkening of the color pattern. The lepidosis of the holotype of L. polylepis agrees well within the range of variation of the poorly known species D. latifasciata (Boulenger, 1913). We had the opportunity of examining the holotype of Leptognathus latifasciatus (BMNH ) (Fig.3) and found it to be very similar to the holotype of L. polylepis (Tab.1). The holotype of L. latifasciatus is a juvenile male collected at Upper Marañon, Eastern Peru, by A.E. Pratt, and has: head distinct from body; body with 299mm in snout-vent length, strongly compressed laterally; tail with 124mm; scutellation, dentition, and number of blotches similar to that observed in the holotype of L. polylepis (Tab.1). PETERS (1960) showed the range of variation of D. latifasciata based on four specimens presenting: 1 or 2 primary temporals (2 on both sides in L. polylepis); secondary temporals 3 (V2-3 in L. polylepis); tertiary temporals 2 or 3 (2 on both sides of L. polylepis); supralabials 8 or 10 (9 on both sides in L. polylepis), fourth and fifth or fourth to sixth contact the orbit (fourth to sixth in L. polylepis); infralabials 10 to 12 (13 and 12 in D. polylepis), first one or two pairs contact behind synphisial (one pair in L. polylepis), four or five pairs in contact with first chin shields (six pairs in L. polylepis); three pairs of chin shields (identic in L. polylepis). Ventrals 180 to 194 (198 in D. polylepis); subcaudals 92 to 114 (94 in L. polylepis). Dorsal scales rows 17 to level fifth to seventh ventral (16 to 18 in L. polylepis); reduction there to 15, which is number over most of body (the dorsal rows are in an irregular pattern in L. polylepis). The dorsum of head of the holotype of L. latifasciatus is dark brown, with white sutures and white spots in loreals and supralabials; occipital region with a white band which curves forward on sides of head to corners of mouth; synphisial and chin shields brown, infralabials and gulars predominantly white with dark-brown spots. Dorsal ground color show a pattern yellowish-brown, with 23 white-edged brown blotches, three to four times wider than interspaces, the majority fused across vertebral line; alternating in the posterior region of body, slightly smaller than interspaces, narrowed at beginning of ventrals but not at vertebral line, the blotches tend to fuse with blotches on other side; interspaces immaculate anteriorly, where the white-edged of brown blotches fuse, yellowish with light brown spots high on sides posteriorly. Venter has the same color as dorsal interspaces, with rectangular light brown spots between ends of dorsal blotches. Thereby, most characters of D. polylepis falls within the range of variation of D. latifasciata, excluded only number of ventrals; however, PETERS (1960) establish sexual dimorphism to Dipsas, with females having more segments and the number of infralabials in contact with first chin shields, six instead five, that is probably explained by large number of fusions and divisions in Dipsas. The differences between the coloration of the holotypes of Leptognathus polylepis and L. latifasciatus are probably result of the characteristic ontogenetic darkening of species from the D. pratti group, as the holotype and all specimens of D.

5 LEPTOGNATHUS LATIFASCIATUS, A JUNIOR SYNONYM OF DIPSAS POLYLEPIS 5 latifasciata examined by PETERS (1960) were juveniles. Considering our observation combined with the data from the four specimens examined by PETERS (1960) and geographical proximity of all known specimens of D. latifascita and D. polylepis (see PETERS, 1960), we suggest that L. latifasciatus should be transferred to the synonymy of D. polylepis. 2 3 Fig.2- The holotype of Leptognathus polylepis Boulenger, 1912 (BMNH ); fig.3- The holotype of Leptognathus latifasciatus Boulenger, 1913 (BMNH ).

6 6 R.FERNANDES, D.S.FERNANDES & P.PASSOS TABLE 1 Selected characters of the holotypes of Dipsas polylepis (Boulenger, 1912) and Dipsas latifasciata (Boulenger, 1913) Dipsas polylepis ( ) Dipsas latifasciata ( ) Postoculars 2 2 Temporal formula (left/right side) 2+2/ /1+3 Supralabials 9 9 Infralabials 13/12 11 Pairs of genials 3 3 Ventrals Subcaudals Number of dorsal blotches Maxillary teeth DISCUSSION PETERS (1960) considered Dipsas latifrontalis (Boulenger, 1905) to be closely related to D. latifasciata, to the point that he speculated that they might be better arranged as subspecies of the same species. PETERS (1960) cited two characters distinguishing these two species: the number of pairs of infralabials in contact before the genials (two instead of one in three of the four specimens examined of D. latifasciata and only five specimens in 55 specimens examined of D. latifrontalis) and the contact of the anteriormost dorsal blotches in the venter of D. latifasciata. We examined a photograph of the holotype of Leptognathus latifrontalis, as well as a few specimens of D. latifrontalis. Although both characters are consistent with our small sample of D. latifrontalis, the holotype of L. polylepis does not has the second pair of infralabials in contact before the genials. The pair of infralabials extends medially more than the usual in other species of Dipsas (the holotype of L. latifasciatus, which was not examined by PETERS, 1960, has both pairs in contact before the genials). As such, a single character appears to hold the difference between D. polylepis and D. latifrontalis. Our sample of D. latifrontalis is insufficient to resolve with confidence the taxonomic relationships between D. polylepis and D. latifrontalis, although it appears to be different species, distinct in coloration. SPECIMENS EXAMINED Dipsas latifrontalis: VENEZUELA: (UMMZ ). ECUADOR: Abitagua (UMMZ 92059); Baños (UMMZ , 92057). Dipsas polylepis: PERU: Huancabamba (BMNH , holotype); Upper Maranõn (BMNH , holotype of Leptognathus latifasciatus). ACKNOWLEDGMENTS We thank M.Wilkinson, B.Clark, and C.McCarthy for the access to the type specimens at the Natural History Museum (BMNH), London, and A.G.Kluge and G. Schneider for the access to the specimens at the Museum of Zoology, University of

7 LEPTOGNATHUS LATIFASCIATUS, A JUNIOR SYNONYM OF DIPSAS POLYLEPIS 7 Michigan (UMMZ). We are also grateful to J.P.Pombal Jr. (MNRJ) for critically reviewing the manuscript and to P.R.Nascimento (MNRJ) for rendering the illustration. The authors thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), the Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior (CAPES), and the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ). LITERATURE CITED AMARAL, A., 1929 Estudos sobre ophidios neotropicos. XVIII. Lista remissiva dos ophidios da região neotropica. Memórias do Instituto Butantan, São Paulo, 4: BRONGERSMA, L.D., 1958 Some features of the Dipsadinae and Pareinae (Serpentes: Colubridae). Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, Amsterdam, 61:7-12. BOULENGER, G.A., 1912 Descriptions of new reptiles from the Andes of South America, preserved in the British Museum. Annual Magazine of Natural History, series 8, London, 10: DOWLING, H.G., 1951 A proposed standard system of counting ventral scales in snakes. British Journal of Herpetology, London, 1: DOWNS, F.L., 1961 Generic reallocation of Tropidodipsas leucomelas Werner. Copeia, Washington, 1961: FERNANDES, R., 1995 Phylogeny of the Dipsadine Snakes. Arlington. 115p. Unpubl. Ph.D. Diss., Univ. of Texas at Arlington. FERNANDES, R.; PORTO, M. & CARAMASCHI, U., 1998 The taxonomic status of Heterorhachis poecilolepis Amaral, Journal of Herpetology, Athens, 32: HOGE, A.R., 1964 [1962] Sur la position systématique de quelques serpents du genre Siphlophis Fitzinger 1843 (Serpentes). Memórias do Instituto Butantan, São Paulo, 30: PETERS, J.A., 1960 The snakes of the subfamily Dipsadinae. Miscelaneous Publications of the Museum of Zoology, The University of Michigan, Ann Arbor, 114: PETERS, J.A., 1970 Generic position of the South American snake Tropidodipsas perijanensis. Copeia, Washington, 1970: