Tropidodipsas tricolor, Grünwald & Toribio-Jiménez & Montaño-Ruvalcaba & Franz-Chávez & Peñaloza-Montaño & Barrera-Nava & Jones & Rodriguez & Hughes & Strickland & Reyes-Velasco, 2021
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publication ID |
https://dx.doi.org/10.3897/herpetozoa.34.e69176 |
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persistent identifier |
https://treatment.plazi.org/id/28341FDE-2047-5C1F-A01F-948E25A1B3DA |
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treatment provided by |
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scientific name |
Tropidodipsas tricolor |
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sp. nov. |
Tropidodipsas tricolor sp. nov.
Figs 1 View Figure 1 , 2 View Figure 2
Holotype.
(Fig. 1 View Figure 1 ) INIRENA 2800 (original field number CIG 1837). Juvenile male, collected at 1.5 km east of Río Verde, Municipio de Atoyac de Álvarez, (17.3131°, -100.1969°, datum=WGS84, 971 m a.s.l.), Guerrero, Mexico (Fig. 3A View Figure 3 ) on August 14th, 2020 by Miguel A. Peñaloza-Montaño, Jason M. Jones and Jacobo Reyes-Velasco.
Paratypes.
(2) (Figs 2C-D View Figure 2 ) INIRENA 2799 (original field number CIG 1596). Adult of unknown sex, DOR, collected at 26 km N of Putla Villa de Guerrero, on Putla Villa de Guerrero - Oaxaca Hwy., Municipality of Putla de Guerrero (17.1494°, -97.8709°, datum=WGS84, 1785 m a.s.l.), Oaxaca, Mexico, on September 4th, 2019 by Christoph I. Grünwald, Christopher M. Rodriguez and Carmen Mendoza-Portilla; INIRENA 2798 (original field number CIG 1863). Adult female, DOR, collected at 4.5 km NW of Mixtecapa, on the road to Malinaltepec, Municipio de Malinaltepec, (17.2539°, -98.6406°, datum=WGS84, 1815 m a.s.l.), Guerrero, Mexico on October 21st, 2020 by Tziuhtécatl Sánchez-Luna.
Diagnosis.
Tropidodipsas tricolor sp. nov. is placed in the genus Tropidodipsas based on phylogenetic evidence (Fig. 6 View Figure 6 ). It belongs to the Tropidodipsas fasciata group as defined by Kofron (1987) based on possessing a laterally compressed body, head distinctly wider than neck, protruding eyes of moderate to large diameter, vertebral and paravertebral scales not wider than other dorsal scales, 17 maxillary teeth, 18 dentary teeth, postmental scale absent. The species differs from all described species of Tropidodipsas based on the following combination of characters: (1) 15/15/15 rows of smooth dorsal scales with no enlarged vertebral row; (2) prefrontal broader than long, entering the orbit; (3) loreal square, equally long as high, not entering the orbit; (4) 183 ventral scales in males, 183 in females; (5) 78-79 divided subcaudals in males and 79 in females; (6) 19-22 reddish orange, light-edged bands on body, most with dark brown or black medial stippling, giving the snake a “tricolor” effect; 8 pale bands on tail; (7) ground color black or nearly so; (8) iris chocolate brown; (9) TL/SVL 0.31 in one male specimen, and 0.30 in one female specimen.
Comparisons.
Tropidodipsas tricolor sp. nov. is most similar to T. philippii , T. fasciata , T. guerreroensis and the new species described below. It is the only species of snail-sucker in Mexico with a tricolor pattern, although similar patterns exist in Central American (e.g., Sibon anthracops ) and South American (e.g., Dipsas bobridgelyi ) snail-suckers. It is distinguished from other Mexican snail-suckers such as the Geophis chalybeus species group, the Geophis omiltemanus species group, G. sartorii new comb., G. annuliferus new comb., Tropidodipsas fischeri (Fig. 9C,D View Figure 9 ), S. carri , G. sanniolus new comb. and S. linearis by the laterally compressed body shape and the tri-colored pattern. Further, it differs from other snail-sucker species (character states in parenthesis) as follows: It differs from S. anthracops by possessing 15 scale rows at midbody (vs. 13), possessing a prefrontal that enters the orbit (vs. prefrontal does not enter orbit), loreal not entering the orbit (vs. loreal enters orbit). It may be distinguished from S. dimidiatus by its noticeably different tricolor banded dorsal coloration (vs. brown snake with dark blotches, spots or an undulating stripe) and by lacking a post-mental scale (vs. usually one or two post-mental scales present) and by possessing less than 80 subcaudals in males (vs. 96-144). It is distinguished from Sibon nebulatus (Fig. 9A,B View Figure 9 ) by possessing tricolor body bands (vs. a nebulated black, grey and white pattern with no red outlines in the pale bands), and by vertebral scales not enlarged (vs. row of vertebral scales 1.25-1.35 times larger than other dorsal scales).
This species differs from Dipsas gaigeae by having 15 dorsal scale rows at mid-body (vs. 13), possessing more than 180 ventral scales (vs. 155-169) and a loreal that does not enter orbit (vs. loreal entering orbit). Distinct from D. brevifacies by possessing more than 180 ventrals (vs. 162-180), always possessing the prefrontal in contact with orbit (vs. usually not), never possessing a loreal in contact with orbit (vs. usually in contact), usually possessing 1+2 temporals (vs. usually 2+3), and usually possessing one pair of infralabials in contact after the mental (vs. usually two pairs of infralabials in contact after the mental).
Within Tropidodipsas , T. tricolor sp. nov. differs from T. fasciata and T. guerreroensis by possessing 15 smooth dorsal scale rows (vs. 17 keeled scale rows) and by prefrontal entering orbit (vs. not entering orbit). It differs from the new species described below ( Tropidodipsas papavericola sp. nov.; see below) by tricolor outline in pale dorsal bands (vs. unicolor pales body bands), 19-22 reddish orange body bands (vs. 25-33 pale body bands), by possessing a prefrontal which enters the orbit (vs. prefrontal not entering orbit), by possessing 78-79 subcaudal scales in males (vs. 69-76), by possessing one preocular (vs. two), by possessing 2-3 postoculars (vs. 1-2), 7-8 supralabials (vs. 5-7), 8-9 infralabials (vs. 6-7), eye-head length ratio 25% (vs. 17-21%), by pale throat coloration with black stippling concentrated toward anterior portion and a black mental (vs. pale throat coloration with random dark spots not concentrated in any specific region and a black and white mental), and a narrower head with less protruding eyes (vs. head noticeably wider than neck and eyes strongly protruberant). It differs from T. philippii (Fig. 8C,D View Figure 8 ) by presenting one preocular (vs. 2-3), prefrontal entering orbit (vs. not entering orbit), supralabials 7-8 (vs. 6-7), 3 gular scales (vs. 5), a longer tail which is 30-31% of SVL in males (vs. 25-29% in males), consistently 19-21 pale body bands (vs. highly variable, from 9-44 according to Kofron (1980, 1987) but usually 11-21, according to our data (n=13), and eye-head length ratio of 25% (vs. 15-23%).
Genetic divergence in a 1,072-bp fragment of mitochondrial cytb gene between T. tricolor sp. nov. and T. papavericola sp. nov. is 13-14%; between T. tricolor sp. nov. and geographically proximate T. fasciata , 14-15%; between T. tricolor sp. nov. and T. guerreroensis , 14-16%; and between T. tricolor sp. nov. and geographically proximate T. philippii , 15-16%.
Description of holotype.
(Fig. 1 View Figure 1 ) INIRENA 2800. Juvenile male. SVL 210 mm; TL 67 mm; TotL 277 mm. HL 8.5 mm (from tip to posterior border of parietal) and 7.7 mm (from snout to posterior commissure of mouth); HW 5.0 mm, head distinct from body, approximately 2 times wider than neck. Snout short, blunt, SL 2.7 mm, contained 3.1 times in the HL, rounded in dorsal and lateral profile. Loreal region tall, canthus rostralis rounded. Rostral 1.4 times as broad as high (2.0 mm broad, 1.4 mm high); internasals broader than long (1.0 mm length, 1.6 mm width), rounded anteriorly, in lateral contact with anterior and posterior nasals; prefrontals relatively large, broader than long (1.7 mm length, 2.0 mm width), nearly rectangular, with posterior edge of scale pointed at supraocular and frontal suture, in median contact with each other and in lateral contact with postnasal, loreal, preocular (lower) and orbit; frontal 1.1 times longer than broad (2.8 mm long, 2.4 mm broad), pentagonal with angular tip posteriorly, in contact with prefrontals, supraoculars and parietals. One moderately large preocular on each side. Single supraocular moderate, in contact with prefrontal, frontal, parietal, and upper postocular. Two moderately large postoculars on each side, lower one slightly larger than upper. Parietal 1.1 times as long as wide(4.3 mm long, 3.9 mm wide), the length of parietal 86% of HL, the common suture between parietals 3.6 mm, 1.3 times longer than frontal. Nasal divided, prenasal slightly taller than postnasal, with combined length of both nasals (1.8 mm) longer than loreal. Loreal small and almost square, 0.9 mm long, 1.0 high on left side, 1.0 mm long, 1.0 mm high on right side, and neither reaching orbit. Eye moderately large, 2.1 mm, 25% of HL. Supralabials 8/7. On the left, first and second supralabials in contact with nasals, second, third and fourth in contact with loreal, fifth and six entering orbit, and seventh largest and in contact with lower postocular and two temporals. On the right, first and second in contact with nasals, second and third in contact with loreal, fourth and fifth entering orbit, and sixth largest and in contact with lower postocular, and two temporals. Temporals 1 + 2 on both sides. Five nuchal scales in contact with parietals.
Mental 2.1 times as broad as long (1.5 mm broad, 0.7 mm long), flat anteriorly, rounded posteriorly with posterior edge coming to a slight point at the suture of the first infralabials, separated from the anterior chinshields by the enlarged first pair of infralabials which are in contact with each other. Infralabials 8 on both sides, 1-5 in contact with anterior chinshields and 5-6 in contact with posterior chinshields, sixth infralabial is largest. Anterior chinshields elongated, much longer than wide, left chinshield 2.4 mm long and 0.9 mm wide (2.7 times as long as wide) and right anterior chinshield 2.6 mm long and 1.0 mm wide (2.6 times as long as wide). Left posterior chinshield 1.9 mm long and 1.1 mm wide (1.7 times as long as wide) and right posterior chinshield 1.8 mm long and 1.1 mm wide (1.6 times as long as wide). Three gular scales. Infralabials and scales in the chin region smooth. Distinct gular fold present, starting on the first ventral scale and running posteriorly to the twentieth ventral scale, then fading out by the twenty-fifth ventral scale. Dorsal scales in 15-15-15 rows, smooth throughout; apical pits not evident. Ventrals 183; anal plate single; subcaudal scales paired, 79 on both sides. Body shape laterally compressed. Pupil elliptical.
Coloration in life of the holotype
(Fig. 1A View Figure 1 ). Dorsal coloration of head, body and tail black with 19 reddish orange, light-edged bands on body (not counting nuchal band) and 9 bands on tail; red-orange color faded on four anteriormost bands. Nuchal band cream and involving latter fifth portion of the parietals and the anterior two and part of the third dorsal scale rows. Body bands 9-19 and all tail bands exhibit scattered dark stippling. The entire snake has a “tricolor” appearance. Pale bands on body and tail 2-4 scale rows long (mean = 3) and wider on the lateral surfaces due to the increased scale size. Head coloration predominately black on dorsal surface and pale cream ventrally. The pale nuchal coloration extends forward onto posterior part of the parietals, and beneath the temporals onto the supralabials. Anterior supralabial black, the others bicolor, posterior supralabial predominately cream on both sides but with black flecking in the middle. Dark body color almost complete ventrally, occasionally interrupted mid-ventrally by a pale line. Light dorsal bands are complete ventrally but with dark flecking towards posterior part of body. Reddish orange coloration of dorsal bands does not continue onto the venter. Anal plate bicolored, black on the margins and pale cream in the middle. First dark band on tail interrupted mid-ventrally by pale cream coloration, the other dark and pale bands on tail complete ventrally. Tail tip black above, pale orange below. Pupil pale gray, iris chocolate brown in life.
Coloration in preservative of the holotype
(Figs 1B-E View Figure 1 ). General coloration tricolor. Reddish orange wedge-shaped markings have turned pale brown; the pale cream and orangish bands faded to white.
Variation.
Meristic variation of the three available specimens is given in Table 3 View Table 3 . One paratype (INIRENA 2798) possesses a tiny second preocular above the large lower preocular on both sides. This small scale does not prevent the prefrontal from entering the orbit as in the other specimens and may be a division of the lower preocular.
Two individuals were photographed by Peter Heimes in Guerrero in 2007. While these individuals were not collected or examined in detail, they are likely of this species. As we lack photos of variation of this new species in life, we have included photos of these two individuals which most probably belong to this species (Fig. 2A,B View Figure 2 ).
Dentition.
One paratype (INIRENA 2798) has 17 maxillary teeth (including three empty sockets) on the right side. The same specimen had 18 dentary teeth (including one empty socket) on the right side.
Distribution, habitat and ecology.
This species appears to be restricted to moderate elevations in Sierra Madre del Sur from central Guerrero to western Oaxaca (Fig. 10 View Figure 10 ). Habitats include cloud forest, mesic pine-oak woodland, tropical evergreen forest, tropical semi-deciduous forest and combinations of those assemblages ( Brown et al. 2007). Known from 700-2200 m a.s.l., though most localities are from 1700-2200 m a.s.l. with the exception of the Sierra de Atoyac where it has been found at 700-1000 m a.s.l. in mesic tropical evergreen forest (Fig. 3A View Figure 3 ). Specimens were found at night on low or medium (1.5-3.0 m) vegetation, or dead on the road.
Etymology.
The specific epithet tricolor refers to the tricolor pattern of the black dorsal coloration interspersed by light dorsal bands of cream and reddish orange.
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