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7 August 2020 A New Species of Snail-Eating Snake, Dipsas Cope, 1860 (Serpentes: Colubridae: Dipsadinae), from the Atlantic Forest of Brazil
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Abstract

We describe a new species of snail-eating snake from two localities within the Atlantic Forest of the states of Bahia and Minas Gerais, Brazil. The new species differs remarkably from all congeners by its dorsal pattern consisting of sharply bordered triangles resembling the pattern of sympatric pitvipers, more precisely Bothrops jararaca and B. pirajai. Parameters of external morphology of the new species resemble those of the Dipsas incerta species group. Its scalation, body/head shape, and color pattern are most similar to D. alternans, a species known to occur 360 km farther south, across the Rio Doce river. The new species differs from D. alternans by exhibiting triangular dorsal blotches and a higher number of pileus blotches, by the distribution of ventral spots and morphology of the supratemporal and premaxillae, as well as in hemipenial morphology. We also provide comparisons of the new species with all sympatric and/or parapatric congeners. The finding of a new snake species in the Atlantic rainforest of southern Bahia and adjacent Minas Gerais is particularly surprising as this region is easily accessible and represents a well-sampled area regarding herpetological surveys in the last decades.

INTRODUCTION

With nearly 700 species, the family Dipsadidae (sensu Zaher et al., 2009) is the largest group of colubroid snakes in the world (Hedges et al., 2009; Zaher et al., 2009). Within this group, the subfamilies Xenodontinae Bonaparte, 1845 and Dipsadinae Bonaparte, 1838 are particularly diverse, with almost 300 species in South America and more than 10 distinct monophyletic groups (Zaher et al., 2009; Grazziotin et al., 2012). The tribe Dipsadini Bonaparte, 1838, as a subunit of the family Dipsadidae, encompasses the snail-eating genera Sibon Fitzinger, 1826 and Dipsas Laurenti, 1768, including the former Sibynomorphus Fitzinger, 1843, recently synonymized with Dipsas (Arteaga et al., 2018).

The genus Dipsas contains 41 species distributed from southern Mexico through Central America and into South America, as far as Argentina, Uruguay, and Paraguay (Uetz et al., 2018). These snakes have small to medium size (rarely longer than 100 cm total length), representing a morphologically unique group specialized for an arboreal, gastropod-eating lifestyle, exhibiting lateral compression of the body, reduction or loss of the mental groove, and inward angling of the maxillary teeth (MacCulloch and Lathrop, 2004). The color pattern is highly polymorphic, but most Dipsas species exhibit dark blotches or rings on a light brown to gray ground color.

Peters (1960) provided an extensive revision of the genus, which was followed by more restricted taxonomic studies of several species groups (e.g., Cadle and Myers, 2003; Cadle, 2005; Lima and Prudente, 2009). However, many South American species remain poorly known because of their rarity, and a confusingly large and often species-overlapping variation of color pattern characters (Cadle and Myers, 2003; Harvey and Embert, 2008; Barros et al., 2012; Arteaga et al., 2018). Harvey (2008) provided a comprehensive review of South American Dipsas, including a diagnosis of the genus based on scalation and hemipenial morphology, as well as a key to South American taxa.

Dipsas species occurring along Brazil's Atlantic Forest have received comparatively less attention. The taxonomic status of some species has been evaluated: D. neivai Amaral, 1926 by Porto and Fernandes (1996), which was later synonymized with D. variegata Duméril et al., 1854 by Harvey and Embert (2008); D. alternans Fischer, 1885 by Passos et al. (2004); D. albifrons Sauvage, 1884 by Passos et al. (2005); and the recent description of a new species, D. sazimai Fernandes et al., 2010.

In January 2016, KM encountered a fresh road-killed Dipsas in Bahia's Atlantic rainforest that could not be clearly referred to any known species from the region. Investigations in Brazilian institutions revealed a second specimen from the Atlantic rainforest of Minas Gerais that was collected in 2004. After comparison with material of other congeners and literature data, we concluded that these two specimens represented a new species that we describe herein.

MATERIALS AND METHODS

Type specimens of the new species are deposited in the collections of Museu Nacional, Universidade Federal do Rio de Janeiro (MNRJ), Rio de Janeiro, state of Rio de Janeiro (holotype); and Museu de Zoologia da Universidade Estadual de Santa Cruz (MZUESC), Ilhéus, state of Bahia (paratype), both in Brazil. Appendix 1 shows information on all other comparative material. Institutional abbreviations follow Sabaj Pérez (2016). For comparison of color and head scalation characters, we used additional dipsadid snakes from the same region of the new species' localities, as well as data from specimens from more distant locations.

Terminology for cephalic shields follows Peters (1964), whereas ventral and subcaudal counts follow Dowling (1951). We performed all measurements using a dial caliper to the nearest 0.1 mm, except for snout–vent length (SVL) and tail length (TL), which we measured with the aid of a ruler to the nearest 1.0 mm. Unless stated otherwise, we performed measurements and descriptions of paired cephalic scales strictly based on the right side of the head; however, we also refer to some meristic bilateral values in a left/right format. We counted body markings (blotches, spots, and dots) separately on each side of the dorsum, since these markings may be asymmetrical. Herein, the term “blotch” refers to any broad (two or more scales long and wide) dorsal and head markings, whereas the term “spot” refers to smaller (1–2 scales long and wide) markings on head, dorsum or venter. The term “dot” refers to any marking substantially smaller than a single scale. We determined sex by presence/absence of a hemipenis determined through a ventral incision at the base of the tail. We defined sexual maturity of males through inspection of convoluted and opaque deferent ducts (Shine, 1988, 1994). We examined maxillae and the Harderian gland of the specimens under a stereoscope, through a narrow incision between supralabials and maxillary arch. We followed Cundall and Irish (2008) for skull terminology. We scanned the head of the holotype of the new species and from closely related or sympatric congeners (Dipsas alternans MNRJ 19595; Dipsas indica Laurenti, 1768 MNRJ 14742; Dipsas sazimai MNRJ 15136 [holotype]) at 50 kV and 160 µA with a high energy microCT Scan at COPPE – Instituto Alberto Cruz Coimbra de Pós-Graduação e Pesquisa de Engenharia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. After acquisition, we produced images of scanned skulls using the FDK algorithm (Feldkamp et al., 1984) and analyzed them with the software CTVox® version 2.7 (Bruker Corporation, 2014). Terminology for hemipenial descriptions follows Dowling and Savage (1960) and Zaher (1999) with minor adaptations based on Harvey and Embert (2008). We modified the method for preserved hemipenis preparation from Pesantes (1994) in replacing KOH with distilled water according to Passos et al. (2016). Prior to the inflation with petroleum jelly, we placed the organs in an ethyl alcohol (70%) solution with Alizarin red for about 10 min to stain the ornamented calcareous structures according to adaptations from original procedures used by Uzzell (1973). We report elevations as meters above sea level (m a.s.l.).

Dipsas bothropoides sp. nov.
(Figs. 1, 2)

  • Holotype (Fig. 1A–B)

  • An adult female (MNRJ 26377) collected on 8 November 2004 by Daniel S. Fernandes and Luciana B. Nascimento at “Fazenda Duas Barras” (near 16°25′0.00″S, 40°2′60.00″W, 800 m a.s.l.), a ranch in the district of Talimã, municipality of Santa Maria do Salto, Minas Gerais, Brazil (Fig. 3).

  • Terra typica

  • Montane Atlantic rainforest in the Serra do Cariri that occurs along the border between the states of Minas Gerais and Bahia and separates the basins of the Jequitinhonha and Buranhém rivers. The type was found within Fazenda Duas Barras, which includes patches of unprotected Atlantic rainforest and well-preserved secondary forests, as well as open pastures associated with cattle breeding (see also Cruz et al., 2007).

  • Paratype ( File S1 (05_FileS1.pdf))

  • An adult male (MZUESC 15828) found freshly killed on state road BA-001 on 23 January 2016 by Konrad Mebert and Carol Cornélio, 2 km northeast of Cachoeira do Tijuipe and 3 km southwest of Txai, Praia (Beach) de Itacarézinho (14°23′43.14″S, 39°2′21.70″W; 53 m a.s.l.), Itacaré, Bahia, Brazil (Figs. 3, 4). We collected no tissue sample from the holotype, but such is available from the paratype at MZUESC.

  • General diagnosis and variation (Figs. 1, 2, File S1)

  • The new species is allocated to the genus Dipsas by possessing the following derived characters combined from Peters (1960), Cadle (2007), and Arteaga et al. (2018): mental sulcus (groove) absent, shape of chinshields (square or polygonal rather than elongate and narrow), more than two pairs of chinshields, absence of supralabial noticeably higher than other supralabials and in contact with postocular, and Harderian gland occupying the entire postorbital region.

  • Dipsas bothropoides sp. nov. (holotype and paratype) is distinguished from all currently recognized congeners by the unique combination of the following morphological characters: (1) dorsal scale rows 15/15/15, smooth; (2) one pair of infralabials in contact posterior to mental; (3) infralabials 8–9, 4–6th or only 4th in contact with second pair of chinshields; gulars separating infralabials from preventrals and ventrals; (4) supralabials 8–9 (4–5th or 5–6th contacting orbit); (5) nasal partially or fully divided; (6) internasal paired or fused; (7) loreal square usually in contact with orbit, but contact can be obstructed by a tiny interjacent scale; (8) preoculars 1 or 2 present above and/or below loreal, excluding prefrontal from orbit; (9) postoculars two, excluding temporals from orbit; (10) temporals 3/3/3, 2/3/2 or 2/3/3; (11) ventrals 183 in female (holotype), 179 in male (paratype); (12) subcaudals 100 in female (holotype) and 110 in male (paratype); (13) head light brown with 3–7 large, black blotches with light to yellow borders on the pileus, including a preorbital band (holotype) or three blotches instead (paratype), with the paratype exhibiting two additional parallel spots diverging anteriorly along the sutures of parietals-frontal-supraoculars; (14) first dorsal blotch (nuchal collar) 2–5 scales long on the mid-dorsals and 10–14 scales long at paraventral portion; (15) dorsum of body medium brown (paratype before preservation) to light brown (preserved holotype) with well-defined dorsal blotches in the shape of triangles with black (paratype before preservation) to dark brown borders, becoming lighter towards the center of the blotch, and an additional cream to yellow border on the flanks (both specimens) and venter (paratype), more prominent anteriorly in the male before preservation; (16) number of dorsal blotches 20–26 ( = 23; SD = 2.9; n = 4 sides) to vent, arranged in pairs and separated by a light, slightly enlarged row of vertebral scales; (17) mid-level of dorsal blotches 4–7 scales long; (18) number of dorsal blotches on the tail 10–16 ( = 13; SD = 2.9; n = 4 sides), dark brown with yellow-cream border, fading increasingly in posterior blotches; (19) venter cream brown anteriorly, becoming variably darker through stippling towards posterior region of body and tail up to exhibit the same coloration as dorsum; (20) maxillary teeth 16–17; (21) pterygoid teeth 16–17; (22) palatine teeth 9/9; (23) hemipenis unilobed with conspicuous capitular arch on asulcate side; (24) capitulum on asulcate face of hemipenis with two lobular longitudinal crests, oriented obliquely and converging medially to tip of organ.

  • The general body habitus of Dipsas bothropoides sp. nov. and its elongate head shape, in particular the preorbital-snout area, as well as some features of color pattern resemble members of the D. incerta species group (sensu Harvey, 2008; Fernandes et al., 2010). This group currently includes D. sazimai, D. alternans, D. incerta Jan, 1863 (holotype depicted in Jan and Sordelli [1870], reprinted in Passos et al. [2004]), and D. praeornata Werner, 1909. The D. incerta group is further defined by having a brown dorsal ground color with darker blotches, a mostly immaculate head with few blotches, 15 dorsal scale rows, and loreal in contact with the orbit, all of which are consistent with our specimens. Although Harvey (2008) and Fernandes et al. (2010) stated that the nuchal collar does not reach the rictus in members of the D. incerta group, a D. alternans specimen depicted in Maia-Carneiro et al. (2012) appears to show a nuchal collar that may reach the rictus, as it does in the new species.

  • Description of the holotype (Figs. 1A–B, 2)

  • Adult female, SVL 420 mm, TL 160 mm (38% SVL); head strongly distinct from body, head length 16.2 mm (3.8% SVL), head width 9.9 mm (61.1% head length) at widest point, head height 6.3 mm at tallest point; interocular distance 6.1 mm; snout–orbit distance 4.0 mm (0.65 times interocular distance); nostril–orbit distance 3.1 mm (0.5 times interocular distance); rostral subtriangular, 3.4 mm wide and 1.9 mm high, slightly visible in dorsal view; internasal about twice as wide (2.0 mm) as long (1.1 mm); prefrontal suture sinistral with respect to internasal suture; prefrontals about as long (2.8 mm) as wide (2.6 mm); prefrontals not in contact with orbit; frontal hexagonal, 3.7 mm long and 3.3 mm wide; supraocular 3.7 mm long and 2.2 mm wide; parietal length about 1.70 times (5.8 mm) width (4.1 mm); nasal divided; prenasal about as high (1.6 mm) as long (1.5 mm); nostril positioned in the center of prenasal; postnasal twice as high (1.8 mm) as long (0.8 mm); loreal single, rectangular, 1.3 mm long and 1.6 mm high; loreal contacting second and third supralabials ventrally, orbit posteriorly and preocular dorsally; preocular single, as high (1.0 mm) as long (0.9 mm), entering orbit posteriorly; preocular contacting prefrontal anterodorsally and supraocular posterodorsally; eye diameter 3.4 mm; pupil elliptical; postoculars 2/2, upper postocular higher (1.8 mm) and slightly longer (1.2 mm) than lower postocular (1.0 mm high and long); temporals 3+3+3 on both sides of head; anterior two temporals trapezoidal, together 2.2 mm high and long; supralabials 9/9, 3rd, 4th and 5th entering orbit; 6th supralabial tallest (1.7 mm high and 2.0 mm long), 8th supralabial longest (1.3 mm high and 2.5 mm long); mental triangular, about twice as wide (2.2 mm) as long (1.0 mm); infralabials 9/9, first pair in contact with posterior mental, 1st to 4th contacting first chinshields; 4th to 5th on the left and only 4th on the right side contacting second chinshields; first pair of chinshields 2.6 mm long and 1.7 mm wide; second pair 2.5 mm long and 2.0 mm wide; dorsals smooth in 15/15/15 rows; vertebral row 40% broader than adjacent dorsals from anterior region to mid-body, reducing to 20% broader posteriorly; dorsal rows on tail at level of second subcaudal eight on right and seven on left side; three preventrals; three series of gulars between last infralabial and preventrals; ventrals 183; cloacal plate entire; subcaudals 100 plus a terminal spine, longer than the two last subcaudals, conical with acuminated tip; maxillary teeth 16/17; pterygoid teeth 16/17; palatine teeth 9/9; harderian gland 3.1 mm long and 2.8 mm high, occupying the entire postorbital region.

  • The color pattern of the preserved holotype resembles very much that of the recently collected paratype (see both in Fig. 1), although somewhat faded. Pupil black; dorsal ground color of head light brown; dorsum of head with three large black pileus blotches cream-brown bordered, two parietal blotches elongate, approximately parallel, slightly divergent anteriorly, covering most of parietal scale; left parietal blotch barely extending onto supraocular, right blotch restricted to parietal scale; third pileus black preorbital blotch (transversal band) extending from anterior portion of frontal/supraoculars to middle of prefrontals, reaching preocular laterally; supralabials light brown dorsally, gradually changing to cream along ventral edge; infralabials cream with dark brown spots along suture region with chinshields; chinshields and gulars cream with scattered dark brown spots; gular region cream to white; dorsal ground color of body light brown with 20/21 (left/right) dorsal blotches on the body and 11/10 blotches on the tail; nuchal collar (= first dorsal blotch) butterfly-shaped (12 scales long on paraventral portion and five scales long at mid-dorsals), framed by light border of one scale width; nuchal collar not contacting parietals, but contacts rictus (= posterior end of mouth opening); all dorsal blotches except anteriormost shaped as dark brown triangles, usually bilaterally paired with some displacements along body axis of paratype, generating bilateral difference of three blotches ( File S1 (05_FileS1.pdf)); dorsal blotches dark brown, becoming lighter brown (or yellow in the paratype before preservation) towards center with adjacent scales cream (yellow in paratype), producing light margin, pronounced anteriorly. Blotches pointed dorsally, 1–3 scales wide next to mid-dorsals; base of triangles 4–7 scales wide next to ventrals; spaces between blotches longer than blotches mid-laterally; interspaces 1–5 scales long near ventrals, distance between blotches decreasing posteriorly to 2–3 scales at base of tail; interspaces with short, narrow, irregular dark brown scattered streaks, particularly on anterior portion of body; venter of body cream-brown with higher concentration of dots in posterior region, rendering ventral portion of tail almost uniformly brown; each ventral scale with groups of 3–6 lateral, sequentially arranged, squared or triangular dark brown spots forming irregular stripes along the venter; spots often representing ventral edge of dorsal triangular blotches; ventral spots opposite lateral interspaces located more mid-ventrally.

  • Hemipenial morphology (Fig. 5)

  • Description based on fully everted and expanded organ of paratype. Organ unilobed, cylindrical, with bulbous shape, larger at hemipenial body; strongly capitate; capitulum completely encircling organ, occupying more than half of hemipenial body on sulcate side and less than half of hemipenial body on asulcate side; capitulum ornamented with numerous calyces, more concentrated on sulcate side; papillate calyces gradually replacing spinulate calyces towards apex of capitulum; asulcate side of hemipenis with medial retraction of capitulum (= capitular arch sensu Harvey and Embert, 2008) and conspicuous lobular crests (sensu Passos et al., 2013); lobular crests formed by high concentration of calyces; each ramus of lobular crest obliquely oriented and converging medially to tip of organ; sulcus spermaticus bifurcated inside capitulum at about midpoint of organ; branches with centrolineal orientation at basal portion of hemipenis, diverging to more centrifugal position and terminating almost at distal region of lobes; distal portion of hemipenial body with large spines (ca. 20 on sulcate side, ca. 30 on asulcate side) arranged in several rows and concentrated on lateral portion of sulcate side and adjacent to capitulum in asulcate side; few spines from base to mid-portion of asulcate side of hemipenis; proximal region with spinules among large spines on both sides, more concentrated at level of capitular sulcus on sulcate side and on basal region of asulcate side.

  • Comparisons of internal characters

  • Dipsas bothropoides sp. nov. is distinguished from the two related congeners of the D. incerta group in the Atlantic Forest, D. alternans and D. sazimai, by skull features (Fig. 6), such as: supratemporal bone exceeding anterior and posterior portions of supraoccipital dorsally and quadrate ventrally (vs. supratemporal not reaching anterior or posterior level); ascending process of premaxillae projected posteriorly, contacting nasals dorsally (vs. ascending process of premaxillae not approaching nasals dorsally); and anterior portion of premaxillae exceeding level of nasals dorsally (vs. anterior region of premaxillae not reaching the level of nasals dorsally).

  • The new species differs from all sympatric congeners except D. sazimai and D. variegata by having a capitular arch on the asulcate side of the hemipenis. Dipsas bothropoides sp. nov. differs from D. sazimai by having the capitulum on the asulcate side of the hemipenis with two longitudinal, obliquely oriented crests converging medially towards the tip of organ (vs. capitulum on the asulcate side of hemipenis lacking crests). Dipsas bothropoides sp. nov. differs from D. variegata by having a unilobed hemipenis (vs. moderately bilobed; see Porto and Fernandes, 1996). Finally, the capitular arch in D. bothropoides sp. nov. is curved proximally towards the sulcus (half-distal convex inclination), which is non-curved and horizontal in D. alternans.

  • To facilitate understanding differences based on external characters for field observations and identifications, we arrange the following comparisons in two sections: (1) comparison with other species of the D. incerta group, all apparently allopatric; (2) comparison with other Dipsas species that are sympatric with the new species. In both sections, characters of the congeners compared with the new species appear in parentheses if not otherwise noted.

  • Comparison of external characters within the Dipsas incerta group

  • Dipsas bothropoides sp. nov. differs from D. incerta (Passos et al., 2004: fig. 4) and D. praeornata (Fig. 7D) by its triangular dorsal blotches, dark iris, and 9 infralabials (vs. rhomboid to ovoid dorsal blotches, light iris, and 11–14 infralabials). Furthermore, D. incerta and D. praeornata have been documented only from several sites within Venezuela and the Guiana region, 2,000–3,000 km from the new species (Jan, 1863; Harvey, 2008; Lotzkat et al., 2008; Natera-Mumaw et al., 2015), and thus can be safely excluded as being conspecific with D. bothropoides sp. nov. In the latter two publications, D. praeornata is listed and treated as D. latifrontalis. However, D. latifrontalis belongs to the Dipsas peruana group (Arteaga et al., 2018), and until a more detailed analysis clarifies the problem, we assign all D. latifrontalis from those two publications to D. praeornata, except for the holotype, BMNH 1946.1.20.98.

  • Dipsas bothropoides sp. nov. resembles D. alternans in all scalation characters (see Table 1, Figs. 7B, 8D, Passos et al. [2004], and details below), but differs from it in the following parameters: color pattern, including black dorsal triangular blotches with light centers and yellow-cream borders fading towards the tail tip (vs. rounded dorsal dark brown blotches that may have a white border); 3–7 large, yellow-bordered pileus blotches on top of head (vs. 2–3 large, yellow-bordered blotches, although some specimens display several small black spots with no light border); groups of tightly arranged square brown ventral spots, increasing posteriorly along lateral margins of ventrals, and alternating with groups of spots closer to mid-venter (vs. fewer and more loosely arranged groups of ventral spots, often triangular and narrower, predominantly along lateral margins of ventrals). Prefrontals not in contact with orbit, as in D. alternans, although contact occurs occasionally in the latter species (e.g., D. alternans IBSP 22889). However, D. alternans is known only from southeastern Brazil, with the nearest records ca. 360 km south at Baixo Guandu (IBSP 9280) and 400 km at Santa Teresa (MNB R704), Espírito Santo (Fig. 3; Peters, 1960; Passos et al., 2004).

  • From the Dipsas incerta group, only D. sazimai is known to occur within or near Brazil's northeastern Atlantic coastal belt (Fig. 3) and might be sympatric with D. bothropoides sp. nov. in mountains up to 100 km from the Atlantic coast of northeastern Brazil (Fernandes et al., 2010; Roberto et al., 2014), but not at the lowland locality of the new species. Dipsas bothropoides sp. nov. differs from D. sazimai in the following characters (Figs. 2, 7A, C, 8A–C): prefrontals not contacting orbit (vs. prefrontals in contact with orbit); gulars separating second pair of chinshields from infralabials (vs. infralabials in direct contact with second pair of chinshields); triangular dark-edged dorsal blotches with light centers slightly shorter than interspaces throughout the body and tail (vs. rounded dorsal dark brown blotches generally wider than interspaces becoming lighter and narrower posteriorly, some with a thin vertical line with an increasing size of interspaces); immaculate interspaces throughout body (vs. posterior interspaces can exhibit a thin vertical line); 3–7 large pileus blotches with yellow borders (vs. variable number of medium to large black blotches without yellow border, although some specimens have several small black spots instead); groups of brown, square ventral spots along lateral margins of ventrals, alternating with similar but smaller groups closer to mid-venter (vs. groups of ventral spots, or spots forming an uninterrupted, continuous line only along lateral margins of ventrals, not alternating with mid-venter brown groups, spots increasing in size posteriorly in some specimens).

  • Comparison of external characters with sympatric arboreal Dipsas species

  • We compared D. bothropoides sp. nov. with four sympatric Dipsas species (see Argôlo, 2004): (1) D. catesbyi Sentzen, 1796; (2) D. variegata (including former D. neivai, which represents the Atlantic Forest populations of the widespread D. variegata; Harvey and Embert, 2008); (3) D. indica sensu lato; and (4) D. albifrons (Dias et al., 2018). Dipsas bothropoides sp. nov. differs from D. catesbyi (Figs. 6G, 7H) by: yellow-brown head with a few yellow-bordered black blotches (vs. strongly contrasting black-and-white color pattern on the head with a black-cap extending below the eye); dorsal ground color brown with triangular light centered blotches and a relatively constant blotch/interspace ratio posteriorly (vs. large black-and-white transversal bands anteriorly changing posteriorly to a red-brown body color with oval black bilateral blotches or saddles, blotch/interspace ratio decreasing posteriorly); loreal contacting the orbit, two temporals posterior to postoculars, and vertebral scales only moderately enlarged, 1.4 times larger than adjacent dorsals (vs. loreal not contacting orbit, usually single first large temporal [but see variation among D. catesbyi from the Amazon in Lima and Prudente, 2009], and large expanded vertebral scales 2–3 times wider than adjacent dorsal scales); dorsals 15 (vs. 13 in D. catesbyi); ventrals 179–183 (vs. 186–201 in Bahia specimens of D. catesbyi, in contrast to D. catesbyi males from the Amazon with ventrals as few as 160, see Lima and Prudente, 2009).

  • The new species differs from Dipsas indica (Figs. 7I, 8G), D. variegata (Figs. 7F, J, 8E), and D. albifrons (Figs. 7E, 8F) by: head more elongate (see Peters, 1960 for description of head truncation in these species), particularly preorbital area (vs. a comparatively shorter, but higher snout, and larger eyes resulting in a convex supraocular) and with corresponding different cephalic scale arrangement. For example, D. bothropoides sp. nov. exhibits predominantly square labials, and only two first infralabials narrow and vertically elongate (vs. anterior 2–5 supralabials and 2–6 infralabials are narrow and tall in D. indica, D. varieagta, and D. albifrons); first pair of infralabials contacting each other behind mental scale (vs. 1st and 2nd pair of infralabials contacting each other behind mental scale in D. variegata, although this number is variable in D. indica and D. albifrons); 1st to 4th infralabials in contact with 1st chinshield on each side (vs. usually 2nd to 5th, but less frequently also 6th infralabials in contact with 1st chinshield in D. indica, D. variegata, and D. albifrons); 100–110 subcaudals (vs. 76–93 in D. variegata and 70–96 in D. albifrons; Passos et al., 2005), although this character overlaps with D. indica (Peters, 1960; Hoge and Romano, 1975; Porto, 1993); 15 dorsal scale rows at mid-body (vs. 13 in D. indica), while D. variegata and D. albifrons also exhibit 15 rows; dorsal pattern of strongly black-bordered, straight-sided, upward pointed, light centered triangles with blank and light brown interspaces. The dorsal pattern of D. indica comprises subtriangular, trapezoidal to rounded dark gray-brown to light brown filled blotches or saddles, not bordered by thick straight-sided borders, with interspaces being blank or exhibiting a dark spot (small or none in some specimens in southern Bahia) and paraventral white or yellow blotch, while the dorsal patterns of D. variegata from southern Bahia and D. albifrons are composed of dorsal blotches/saddles vertically stretched rhomboids (more common in D. variegata than in D. albifrons) or bars (less common in D. variegata than in D. albifrons) often with a light center (more common in D. variegata than in D. albifrons) and border zig-zag shaped following the outline of adjacent dorsals, with variable spots in interspaces in D. variegata, rarely in D. albifrons; morphs of Dipsas spp. with straight-sided triangular blotches are rare, but occur in one D. variegata, MNRJ 22771, and more often in allopatric populations of D. variegata from Venezuela (Lotzkat et al., 2008, Natera-Mumaw et al., 2015); cephalic color pattern of D. bothropoides sp. nov. yellow to brown with 3–7 large, dark, light-bordered blotches arranged symmetrically on the pileus (vs. in D. indica: gray to brown with greater number of dark variably sized, yellow-bordered pileus spots not symmetrically arranged except for two parietal blotches; in D. albifrons: unspotted light-colored head with two parallel dark brown blotches extending from parietals onto the neck, occasionally inter-preorbital blotch and brown frontal/parietals; and in D. variegata: variable yellow or brown background, no pileus blotches); eye black (vs. lighter in D. variegata or D. albifrons, and in local D. indica, though the latter species contains some darker morphs with dark eyes, but not as black as in D. bothropoides); ventral pattern consisting of many small square spots (vs. small dots, speckling, or mottled white becoming darker posteriorly in some D. indica, D. albifrons, and D. variegata). Moreover, regional (southern Bahia) D. indica usually possesses a yellow margin (reduced to a few dots or none in some specimens), predominantly along scales contiguous with the eye but also on other cephalic scales, unlike other regional Dipsas species. Dipsas bothropoides sp. nov. has a nuchal blotch < 4 vertebral scales, as in D. variegata or D. albifrons (but > 4 vertebral scales in D. indica), that reaches the rictus, as in most regional D. indica from Bahia, also absent in D. variegata or D. albifrons.

  • Etymology

  • The specific epithet represents the Latinized form of “bothros” derived from the Greek (ßóθρς), referring to the facial pit, and also referring to the genus Bothrops, the species-rich terrestrial Neotropical pitvipers. The suffix -oides means ‘similar to' or ‘having the nature of,’ in reference to the great similarity of the dorsal color pattern with many members of the genus Bothrops, especially the sympatric B. jararaca and B. pirajai.

  • Habitat and climate

  • Both localities of Dipsas bothropoides sp. nov. lie within remnants of the once extensive Atlantic Forest ecoregion, a dense ombrophilous rainforest with a uniform canopy ca. 25 m in height and a dense understory (IBGE, 2012), or tropical moist forest following the Hold-ridge life zones classification (Hartshorn, 1991). However, the two specimens originate from different elevations; the paratype is from near sea level and the is holotype from more inland mountains at 700–1,000 m a.s.l.

  • The area in a radius of 3 km around the type locality of Dipsas bothropoides sp. nov. is hilly and covered by a complex combination of submontane tropical rainforest with semi-deciduous seasonal forest that experiences a dry period. Secondary forests and many patches of pasture make up a mosaic of wooded and open disturbed areas. The annual rainfall is at least 1,000–2,000 mm (Landau, 2003) but might be locally higher. The climate is a transition between Köppen Class Af (aseasonal, warm and humid), Class Am (seasonal monsoon), and Class Aw (tropical savanna with a pronounced dry season).

  • The 3 km around the paratype's location consists of undulating to rolling hills (10–30% slope), stretching from sea level to ca. 130 m a.s.l. with a straight-line distance of 2.7 km to the Atlantic coast. The vegetation is a mixture of agriculture/pasture, secondary forest at different succession stages (Fig. 4), mixed with patches of recently to old (> 30 years) logged forests. The nearest old growth forest is located 6 km south (Martini et al., 2007). The lowland climate is warm and humid, without a well-defined dry season (Köppen Class Af). Monthly average temperature is 24°C, with July to August being coldest and November to March being warmest. The annual rainfall of 2,400–2,600 mm (Landau, 2003) is well distributed throughout the year, with relative humidity often exceeding 80% (Sá et al., 1982).

  • Figure 1.

    (A) Dorsal and (B) ventral views of the holotype of Dipsas bothropoides sp. nov. (MNRJ 26377, female, snout–vent length [SVL] 420 mm); and (C) dorsal and (D) ventral views of the paratype of Dipsas bothropoides sp. nov. (MZUESC 15828, male, SVL 339 mm). Small inset show small section of the mid-body of respective specimens, illustrating the enlarged vertebral scales.

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    Figure 2.

    Close views of the holotype of Dipsas bothropoides sp. nov. (MNRJ 26377, female): left side (A) dorsal, (B) lateral, and (C) ventral views of the head, and right side with lateral views of body on its (D) anterior, (E) medial, and (F) posterior regions.

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    Figure 3.

    Map showing the two known localities of Dipsas bothropoides sp. nov. The lower red circle is the holotype, the upper red circle the paratype. Locality records of D. sazimai are based on Fernandes et al. (2010), Roberto et al. (2014), Freitas (2015), and unpublished records by Iuri Ribeiro Dias, see Figs. 7C and 8C; D. alternans (according to Passos et al., 2004; Nogueira et al., 2019), and D. albifrons (Dias et al., 2018 and complementing records from Nogueira et al., 2019). Small inset shows map of South America.

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    Figure 4.

    Habitat where the paratype of Dipsas bothropoides sp. nov. was found: (A) general view of the landscape at Atlantic Forest near Itacaré, north of the terra paratypica; (B) Rio do Tijuipe near the location of collection; (C) forest habitat near the terra paratypica.

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    Figure 5.

    (A) Sulcate, (B) lateral, and (C) asulcate views of the hemipenis of the paratype (MZUESC 15828) of Dipsas bothropoides sp. nov.

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    Figure 6.

    Dorsal and lateral views of the skull of (A) Dipsas bothropoides sp. nov., (B) D. alternans, and (C) D. sazimai. Arrows indicate diagnostic features of the new taxon. Scale bars = 1 mm.