Thamnodynastes longicaudus Franco, Ferreira, Marques & Sazima, 2003, sp. nov.
Creators: name: Franco, Francisco Luís
name: Ferreira, Talita Gancev
name: Marques, Otavio A. V.
name: Sazima, Ivan
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Colubridae
Thamnodynastes
Thamnodynastes longicaudus

description: Thamnodynastes longicaudus sp. nov.
(Figures 1–3)
Thamnodynastes sp. 2 (colour photo of holotype) Marques et al., 2001: 152.
Thamnodynastes sp. 4 (morphological characters) Franco and Ferreira, 2003: 57 –74.
Type Material — Holotype: IB 59545, (male, 370 mm SVL, 204 mm TAL), BRAZIL, São Paulo, São Lourenço da Serra (23°51’S – 46°56’W, 690 m a.s.l), 22 Dez. 1998, M. D. Galante. Paratypes: IB 18676, (male, 289 mm SVL, 147 mm TAL), BRAZIL, São Paulo, Salesópolis, Estação Biológica de Boracéia (23°38’S – 45°52’W, 900 m a.s.l.), 0 9 Jan. 1960, Medeiros; IB 20694, (male, 300 mm SVL, 155 mm TAL), BRAZIL, São Paulo, Itapecerica da Serra (23°43’S – 46°50’W, 906 m a.s.l.), 0 4 Aug. 1961, C. Zanuzzi; IB 26561, (male, 144 mm SVL, 75 mm TAL), BRAZIL, São Paulo, Juquitiba (23°55’S – 47°04’W, 685 m a.s.l.), 13 Sept. 1966, X. Langlada; IB 31890, (male, 334 mm SVL, 174 mm TAL), BRAZIL, São Paulo, Areias (22°34’S – 44°41’W, 520 m a.s.l.), 11 Jan. 1971; collector unknown; IB 33702, (male, 351 mm SVL, 195 mm TAL), BRAZIL, São Paulo, Juquitiba (23°55’S – 47°04’W, 685 m a.s.l.), 15 Jan. 1973, P. R. Lang; IB 33706, (male, 325 mm SVL, 182 mm TAL), BRAZIL, São Paulo, Guapiara (24°11’S – 48°31’W, 750 m a.s.l.), 24 Jan. 1973, collector unknown; IB 41045, (male, 411 mm SVL, 219 mm TAL), BRA­ ZIL, Rio de Janeiro, Teresópolis (22°24’S – 42°57’W, 872 m), 29 Oct. 1976, R. W. Waltemath.
Diagnosis — Thamnodynastes longicaudus is a very slender, long­tailed snake (Figure 1), distinguished from all congeners and all other Tachymenini species by its high number of subcaudals (>101). Another very slender species with high number of subcaudals is the Amazonian Thamnodynastes pallidus, which has a maximum count of 99 subcaudal scales (Cunha and Nascimento 1978). Additionally, T. longicaudus has 19 scale rows in the mid body and a divided cloacal scale, whereas T. pallidus has 17 such rows and an entire cloacal scale. The characteristic dorsal series of dark blotches in the fore­body, fully shown in defensive displays (Figure 2), is another diagnostic feature of T. longicaudus.
Description — Holotype (Figures 1–3), adult male, snout­vent length 370 mm, tail length 204 mm, head length 16.2 mm. Body very slender, tail very long (55.1% of SVL). Mass in life 15 g. Dorsal scales smooth lacking apical pits; dorsal scale rows 19/19/13; ventrals 142; cloacal scale divided; subcaudals 105, paired. Nasal single; internasals slightly wider than long and smaller than prefrontals; prefrontals a little wider than long; frontal pentagonal, longer than wide; loreal almost square; preoculars 2 and postoculars 2; temporals 2+3; supralabials 8/8, fourth and fifth in contact with eye; right infralabials 9, left ones 10; anterior and posterior mentals about same size. Eye prominent, pupil elliptical.
Colour pattern — In life ground colour greyish yellow; discrete mid­dorsal stripe composed by light brown blotches from head to mid­body; rest of body with small light brown blotches and spots fading caudally. Series of 5–6 black blotches on fore­body shown during defensive display (Figure 2). Tail greyish yellow to brownish orange with scattered light brown spots, its terminal portion slightly darker. Dorsum of head light brown with scattered darker spots. Light brown postocular stripe from behind eye to corner of mouth. Lower labials, gular region and throat immaculate greyish yellow. Venter greyish yellow slightly lighter than dorsum, with three pairs of darker narrow greyish yellow stripes, the central one less conspicuous. In preservative (ethanol 70%) dark blotches on fore­body become conspicuous on anterior third of body.
Variation — The type series varies mainly in scale counts. Supralabials 7/8 (n = 1), 7/ 9 (n = 1), 8/8 (n = 2), 8/9 (n = 3), 9/9 (n = 1); right oculars 2+2 (n = 7), 3+2 (n = 1); right temporals 2+3 (n = 7), 3+4 (n = 1); infralabials 9/10 (n = 1), 10/9 (n = 2), 10/10 (n = 2), 11/ 9 (n = 1), 11/10 (n = 1), one specimen not counted; dorsal scale rows: 17/19/13 (n = 4), 19/ 17/13 (n = 1), 19/19/13 (n = 3); ventrals 143–149 (= 145 ± 3); subcaudals 101–109 (= 104 ± 3). In preservative (ethanol 70%) ground colour vary from yellowish white to brownish orange; black blotches on fore­body become more conspicuous on anterior third of body.
Etymology — The specific name is an adjective derived from the Latin words longus and caudus, alluding to the very long tail of the new species.
Geographic range — Thamnodynastes longicaudus is presently known from moderate elevations (520–906 m a.s.l.) in the Serra do Mar range, from Teresópolis (22°24’S, 42°57’W) in Rio de Janeiro in the North to Guapiara (24°11’S, 48°31’W) in São Paulo to the South.
Remarks — The slender body and exceedingly long tail of Thamnodynastes longicaudus, besides its distribution restricted to the Atlantic forest, strongly indicate that this snake is among the most arboreal species within the genus. Species of Thamnodynastes, even the stouter species such as T. strigatus, are arboreal to some extent (Strüssmann & Sazima 1993; Bernarde et al. 2000; Marques et al. 2001), and thus arboreality in the slen­ der, new species would not be surprising.
The striking defensive hood­display is currently unrecorded within the genus Thamnodynastes or other tachymenine taxa (pers. obs.). The series of bold markings on the flattened fore­body produce an impressive change in the snake’s appearance, and is likely directed towards visually hunting predators (Greene, 1988). Among arboreal snakes, defensive displays involving the fore­body are limited to lateral flattening (Greene 1979; Marques 1999; Senter 1999). Thus, the hood­display of T. longicaudus seems a rare behaviour among arboreal snakes, possibly derived from the generalised dorso­ventral body flattening found in all Tachymenini and other terrestrial snakes in general (Greene 1979, pers. obs.). The restriction of the flattening to the fore­body in the new species may be related to its arboreal habits.
description: Published as part of Franco, Francisco Luís, Ferreira, Talita Gancev, Marques, Otavio A. V. & Sazima, Ivan, 2003, A new species of hood­displaying Thamnodynastes (Serpentes: Colubridae) from the Atlantic forest in southeast Brazil, pp. 1-7 in Zootaxa 334 on pages 2-6, DOI: 10.5281/zenodo.156299