Helicops nentur, Costa & Santana & Leal & Koroiva & Garcia, 2016

Costa, Henrique C., Santana, Diego J., Leal, Fernando, Koroiva, Ricardo & Garcia, Paulo C. A., 2016, A New Species of Helicops (Serpentes: Dipsadidae: Hydropsini) from Southeastern Brazil, Herpetologica 72 (2), pp. 157-166 : 157-166

Helicops nentur sp. nov.

( Figs. 1–3 ; Table 2 )

Helicops sp. Costa et al. 2010:359.

Helicops sp. Costa et al. 2014:118.

Holotype. — UFMG 2486 , an adult female collected on 8 November 2013 by Fernando Leal at a swamp in Fazenda Papa Capim (18.329398 ° S, 42.092017 ° W, 260 m above sea level [a.s.l.]; in all cases, datum = WGS84 ), São José da Safira , state of Minas Gerais, Brazil ( Figs. 1–2 ).

Paratypes. — Four specimens, all from the Brazilian state of Minas Gerais, as follows : MZUFV 742 , an adult female collected by Lício W. Assad, date unknown, at Jaíba (15.340270 ° S, 43.676862 ° W, ca. 480 m a.s.l.) ; MZUFV 960 , a young male, collector unknown, February 1998 at CBIA (20.713650 ° S, 42.864917 ° W, ca. 640 m a.s.l.) , urban area of Viçosa ; UFMG 175 , an adult female collected by V. X. Silva on 6 January 1999 at the campus of Universidade Federal de Minas Gerais (19.869395 ° S, 43.966480 ° W, ca. 820 m a.s.l.) , Belo Horizonte ; ZUFMS-REP 2291 , a young female collected by Carmen Côrtes Santana Silva on 4 March 2013 at District of Macuco (21.145255 ° S, 42.493443 ° W, ca. 224 m a.s.l.) , Muriaé.

Diagnosis. — Helicops nentur sp. nov. can be diagnosed by the following combination of characters: (1) dorsal scale rows 17–17–15, smooth on the anterior third of body, becoming weakly keeled posteriorly; (2) ventral plates in the male 115, in females 111–117; (3) subcaudals in the male 56, in females 41–52; (4) subcaudal keels absent, dorsal caudal scales keeled; (5) supralabials 8, third and fourth contacting orbit; (6) infralabials 9–10, the first to fifth contacting the first pair of chinshields, the fifth and sixth contacting the second pair of chinshields; (7) intergenials absent; (8) nasal entire; (9) preocular one; (10) postoculars two; (11) temporals 2 + 2 or 2 + 3; (12) maxillary teeth 18–21 + 2; (13) hemipenis bilobed, semicalyculate, semicapitate, with lobes covered by encircling rows of spinulate flounces, body covered by numerous spinules and a few spines arranged in more or less oblique rows; (14) dorsum uniformly medium brown or dark brown; (15) venter cream, yellow, or light brown (sometimes mottled with gray) with two medial rows of black markings, usually semilunar in shape.

Comparisons ( Tables 3–4 ). — Helicops nentur sp. nov. differs from all congeners except H. infrataeniatus by having 17–17–15 dorsal scale rows. It also differs from all other Helicops except H. modestus , H. tapajonicus , H. triƲittatus , and some H. carinicaudus by the presence of weak dorsal keels on the posterior third of body (character unknown in H. ŋacu ). Helicops nentur sp. nov. differs from H. carinicaudus , H. danieli , H. gomesi , H. pastazae , H. petersi , and H. ŋacu by having fewer than 119 ventral scales in both sexes. It further differs from H. apiaka , H. hagmanni , and H. tapajonicus by having fewer than 117 ventrals in males and fewer than 121 in females.

Helicops nentur sp. nov. differs from H. angulatus , H. apiaka , H. danieli , H. gomesi , H. pastazae , H. petersi , H. polŋlepis , H. scalaris , H. tapajonicus , and H. ŋacu by having fewer than 60 subcaudals in both sexes. The presence of 56 subcaudals in the male and 41–52 in the females of H. nentur sp. nov. also distinguishes it from H. triƲittatus (subcaudals 67–80 in males and 56–66 in females) and H. leopardinus (64–89 in males and 53–76 in females). The absence of subcaudal keels distinguish H. nentur sp. nov. from H. angulatus , H. apiaka , H. gomesi , and H. scalaris (character unknown in H. ŋacu ).

In H. nentur sp. nov., the third and fourth supralabials contact the eye, whereas in H. danieli , H. hagmanni , H. pastazae , H. petersi , and H. tapajonicus only the fourth supralabial contacts the eye. This character also distinguishes H. nentur sp. nov. from H. angulatus (fourth, fourth + fifth or fifth supralabial[s] contacting the eye), H. gomesi and H. triƲittatus (fourth or fifth supralabial contacting the eye), H. scalaris (fourth or fourth + fifth supralabial[s] contacting the eye), and H. ŋacu (fourth + fifth supralabials contacting the eye).

The presence of 9–10 infralabials distinguishes H. nentur sp. nov. from H. polŋlepis (11–13), H. triƲittatus (11–14), and H. ŋacu (11–12). Helicops nentur sp. nov. can be further distinguished from H. hagmanni , H. pastazae , H. petersi , H. scalaris , H. triƲittatus , and H. ŋacu by the absence of intergenials separating the second pair of chinshields.

An undivided nasal distinguishes H. nentur sp. nov. from all other Helicops with the exception of H. ŋacu . A single preocular distinguishes H. nentur sp. nov. from H. triƲittatus (two preoculars), and the presence of two anterior temporals distinguishes H. nentur sp. nov. from H. gomesi , H. petersi , H. tapajonicus , H. triƲittatus , and H. ŋacu (one anterior temporal). The presence of ±18 (up to 21) prediastemal maxillary teeth distinguishes H.nentur sp. nov. from H. angulatus , H. apiaka , H. hagmanni , H. pastazae , H. petersi , H. polŋlepis , H. scalaris , and H. ŋacu , all of which have fewer than 18 teeth.

The uniformly colored dorsum of H. nentur sp. nov. is also present in some specimens of H. carinicaudus , H. modestus , and H. tapajonicus . A cream venter with two rows of black semilunar markings is present only in H. nentur sp. nov., H. carinicaudus , H. danieli , and H. triƲittatus . In the latter three species the black ventral markings are strong and welldefined, whereas in H. nentur sp. nov. they are usually less well-defined. In preserved specimens of H. nentur sp. nov., the first dorsal scale row (DSR1) is cream colored, as is the adjacent venter, on the anterior third of the body; posteriorly, the scales of DSR1 become gray dorsally, and occasionally totally gray. In H. carinicaudus DSR 1 is cream colored, whereas DSR2 is gray anteriodorsally, usually becoming totally gray posteriorly; in H. danieli DSR 1 and DSR2 are white or cream colored, similar to the venter ( Rossman 2002a); in H. triƲittatus the scales of DSR1 are cream colored dorsally along the entire body ( Rossman 2010).

In H. carinicaudus there is no gray pigmentation on the outer edges of the ventrals, and sometimes there is a midventral row of poorly defined black semilunar markings ( Yuki and Lema 2005; present study); in H. danieli there is no gray pigmentation on the ventrals, and the black semilunar markings sometimes fuse midventrally ( Rossman 2002a); in H. triƲittatus the black markings are proportionally larger than those of H. nentur sp. nov., and there is no gray pigmentation on the ventrals ( Rossman 2010).

Among the species of Helicops whose hemipenis morphology is described (all but H. petersi and H. ŋacu ), the organ of H. nentur sp. nov. is readily distinguishable from that of H. infrataeniatus , H. leopardinus , H. modestus , and H. tapajonicus in having well-developed lobes. The asulcate side having lateral spines larger than central spines distinguishes the hemipenis of Helicops nentur sp. nov. from that of H. hagmanni , H. infrataeniatus , H. leopardinus , H. modestus , and H. triƲittatus (small spines of uniform size). In H. pastazae , the central spines on the asulcate side are considerably longer than in H. nentur sp. nov. Lobes covered with spinulate flounces distinguish the organ of H. nentur sp. nov. from that of H. apiaka (lobes with plicae), H. danieli , and H. polŋlepis (lobes with small papillae). The spines bordering the sulcus spermaticus in the hemipenis of H. nentur sp. nov. are smaller than those of H. apiaka . The less developed basal pocket in H. nentur sp. nov. distinguishes its hemipenis from that of H. scalaris .

Description of holotype. —Adult female, SVL 334 mm, tail length 77 mm (23% SVL); head rounded in dorsal view, flattened in lateral view, head length 19.13 mm (5.8% SVL), head width 11.92 mm (61.8% head length); no evident cervical constriction; snout rounded in dorsal and lateral views; rostrum–orbit distance 4.1 mm (21.2% head length); nasal– orbit distance 2.37 mm (12.3% head length); interorbital distance 4.64 mm (38.9% head width); eye diameter 2.65 mm, pupil round; rostral subtriangular in frontal view, wider (3.22 mm) than high (1.78 mm), visible from above; internasal single, diamond-shaped, longer (2.2 mm) than wide (1.98 mm); prefrontals two, hexagonal, longer (2.34: 2.35 mm) than wide (1.46: 1.49 mm), in medial contact (prefontal suture 0.81 mm); frontal pentagonal, longer (4.84 mm) than wide (2.56 mm); supraoculars rectangular, longer (3.89: 3.98 mm) than wide (1.61: 1.63 mm); parietals longer (6.18: 6.23 mm maximum length) than wide (3.47: 3.52 mm maximum width); parietal suture 3.95 mm; nasals quadrangular, separated by prefrontal, well visible from above; left nasal semidivided, right nasal entire; loreal quadrangular, contacting nasal anteriorly, prefrontal above, second and third supralabials below, and preocular posteriorly; preocular single, higher (1.90: 1.97 mm) than wide (0.65: 0.60 mm), contacting loreal and prefrontal anteriorly, supraocular above, third supralabial below, and the eye posteriorly; postoculars two; upper postocular (1.33: 1.35 mm high; 1.48: 1.50 mm wide) contacting the eye anteriorly, supraocular and parietal above, lower postocular below, and upper anterior temporal posteriorly; lower postocular (2.17: 2.17 mm high; 1.14: 1.14 mm wide) contacting the eye anteriorly, upper postocular above, fourth to sixth supralabials below, and upper anterior temporal posteriorly; temporals 2 + 2, longer than wide; upper anterior temporal (1.97: 1.96 mm high; 3.56: 3.58 mm long) contacts the postoculars anteriorly, parietal above, sixth supralabial below, lower anterior temporal and upper posterior temporal posteriorly; lower anterior temporal (2.06: 1.65 mm high; 3.67: 3.15 mm long) contacts upper anterior temporal above and anteriorly, sixth and seventh supralabials below, upper posterior temporal above, and lower posterior temporal posteriorly; upper posterior temporal (2.56: 2.59 mm high; 2.92: 2.92 mm long) contacting both anterior temporals anteriorly, parietal above, lower anterior and posterior temporals below, and two small head scales posteriorly; lower posterior temporal (2.2 mm high; 2.45: 2.52 mm long) contacting lower anterior temporal anteriorly, upper posterior temporal above, seventh and eighth supralabials below, and two small head scales posteriorly; supralabials eight, the third and fourth contacting the eye; sixth supralabial higher (3.05: 3.20 mm) and wider (3.25: 3.26 mm) than the others; symphyseal triangular, wider (1.71 mm) than long (1.38 mm); infralabials 10, the first pair in contact behind symphyseal, preventing symphyseal–chinshield contact; first to fifth pair of infralabials contacting first pair of chinshields (genials); fifth and sixth pair of infralabials in contact with second pair of chinshields; intergenial scale absent; chinshields longer (first pair 4.62: 4.50 mm; second pair 5.75: 4.70 mm) than wide (first pair 1.60: 1.62 mm; second pair 1.70: 1.71 mm); dorsal scales in 17–17–15 rows, lacking apical pits, smooth behind the head, becoming weakly keeled posteriorly; keels are more visible on posterior-most region of body and on dorsal surface of tail; gular scales 4:5, between the last infralabial and first preventral; preventrals two, ventral scales 117; cloacal plate divided; 41 divided subcaudals; maxillary teeth 19 + 2.

Color in life of holotype. —Dorsal and lateral surfaces of head dark olive-green; supralabials dark olive-green above, becoming yellowish-green below; infralabials and gular region yellow with scattered olive-green pigment. Ventrals yellow, with two medial rows of black round or semilunar marks (two marks on each ventral); gray pigment between the black marks on each ventral anteriorly; gray pigment more intense and covering entire ventral surface posteriorly. Subcaudals gray, with black medial markings on subcaudals 1–6. Dorsal ground color dark olive-green; DSR1 yellow with olive-green pigments anteriorly.

Color in preservative of holotype ( Fig. 1 ). —Dorsal and lateral surfaces of head dark gray; supralabials 1–5 light gray; supralabials 6–7 cream with gray pigmentation, more intense above; supralabial 8 dark gray above and cream below; infralabials and gular region cream with scattered gray pigment. Ventrals cream, with two medial rows of black round or semilunar marks (two marks on each ventral); gray pigment between the black marks on each ventral anteriorly; gray pigment becoming more intense and covering entire ventral surface posteriorly. Subcaudals grayish, with black medial markings on subcaudals 1–6. Dorsal ground color dark gray; DSR1 cream with gray flecks anteriorly.

Description of hemipenis. —Based on the right hemipenis of the male paratype (MZUFV 960), which was fully everted and almost maximally expanded ( Fig. 3 ). In situ, the everted organ extends to the 14th subcaudal. Hemipenis bilobed, semicalyculate, and semicapitate; body 12.9 mm long, with well-developed lobes (7.5 mm; 58% of hemipenial body length), distinct from the body by a constriction from lateral to asulcate side; lobular crotch with a line of small spines; lobes covered by encircling rows of horizontally oriented spinulate flounces, except at the apices, which are nude; sulcate side covered by several spinules and some small spines arranged in more or less oblique rows; sulcus spermaticus bifurcating in the proximal region, with branches having a S-shaped condition; the asulcate side is covered with spinules and bordered by lateral spines increasing in size from the base to the apex; a small oblique nude area is present in the left and right portions of the asulcate side, close to the edge of capitulum; a basal pocket is present.

Variation. —The single male 154 mm SVL, 45 mm TL; largest female UFMG 175, 650 mm SVL, 140+ mm TL (broken tail); tail 33.9% SVL in the male, 23–29.2% SVL (mean = 25.56 ± 3.23%, n = 3) in females (UFMG 175 not included); ventrals in the male 115, in females 111–117 (mean = 115.2 ± 2.87, n = 4); subcaudals 56 in the male, in females 41–52 (mean = 45.6 ± 5.68, n = 3); preventrals 1–2 (mean = 1.40 ± 0.54, n = 5); prediastemal maxillary teeth 18–21 (mean = 19.40 ± 1.14, n = 5); infralabials on left side in the male 9.

The nasals are undivided in all specimens, with two exceptions: The right nasal of UFMG 2486 is semidivided and the right nasal of MZUFV 742 shows a small sulcus that does not reach the lower part of the nostril. All specimens have two anterior temporals, the upper longer than the lower. Usually there are two posterior temporals unequal in size, but MZUFV 742 has three posterior temporals on the right side, whereas MZUFV 960 has three posterior temporals on the left side.

Color pattern is similar among all examined specimens of H. nentur sp. nov., with few differences, probably of ontogenetic origin. The two smallest specimens—MZUFV 960 and ZUFMS-REP 2291—have less gray pigment in the medial region of the ventrals. In life, the venter was cream in the gular region, yellow on the anterior half of body, and light orange posteriorly in ZUFMS-REP 2291 ( Fig. 4 ).

Natural history and habitat. —Available information (from the holotype and one paratype) suggests that H. nentur sp. nov. inhabits lentic water bodies such as swamps. The holotype was collected while active at 0300 h, partially submerged. After collection, it gave birth to two stillborn specimens not measured nor preserved. ZUFMS-REP 2291 has an umbilical scar on ventrals 91–95. Date of collection of these two specimens suggest that reproduction in H. nentur sp. nov. might occur during the rainy season (October– March).

Geographic distribution. — Helicops nentur sp. nov. is known only from five localities in the Brazilian state of Minas Gerais: Belo Horizonte, Jaíba, Muriaé, São José da Safira, and Viçosa ( Fig. 5 ). The distribution of this species (sensu Olson et al. 2001) is in the Bahia Interior Forest ecoregion (Tropical and Subtropical Moist Broadleaf Forests biome), its border with the Cerrado ecoregion (Tropical and Subtropical Grasslands, Savannas, and Shrublands biome), and the ecotone between the Atlantic Dry Forest and the Caatinga ecoregions (Tropical and Subtropical Dry Broadleaf Forests biome and Deserts and Xeric Shrublands biome). This indicates that H. nentur sp. nov. might occupy different environments and climatic conditions. The distance between collection localities also indicates that there are many distribution gaps in the range of the species.

Etymology. —The specific name nentur has its origin in Quenya, a fictional language created by the late writer and philologist J.R.R. Tolkien. In Tolkien̕s mythology, Quenya is spoken by the Eldar, the High Elves of Valinor, which is a land in the blessed continent of Aman. The name nentur is formed by the words nen (water) and tur (ruler, master), meaning “master of waters,” which is a reference to the aquatic habits of Helicops . The name is treated as a noun in apposition.

Molecular phylogeny and genetic divergence of the new species. —Sequence divergences between H. nentur sp. nov. and other congeners range between 4.0% and 6.0% (mean 4.8%) for 16S rRNA and between 0.0% and 0.4% (mean 0.2%) for C-mos ( Table 5 ). Among those species for which 16S genetic data are available, H. nentur sp. nov. is sister to a clade formed by H. hagmanni , H. angulatus , and H. gomesi ( Fig. 6A ) with high support (bootstrap value = 81%, and posterior probability = 0.99). A partial C-mos tree shows the new species as sister to H. carinicaudus with low bootstrap value (64%) but high posterior probability (0.99; Fig. 6B ).

Figures

FIG. 1.—Holotype of Helicops nentur sp. nov. (UFMG 2486): dorsal (A) and ventral (B) view. Scale bar = 20 mm. A color version of this figure is available online.

FIG. 2.—Holotype of Helicops nentur sp. nov. (UFMG 2486): head in dorsal (A), ventral (B), left (C), and right (D) view. Scale bar = 5 mm. A color version of this figure is available online.

FIG. 3.—Right hemipenis of a paratype of Helicops nentur sp. nov. (MZUFV 960) fully everted and almost maximally expanded: sulcate (A) and asulcate (B) side. Scale bar = 10 mm. A color version of this figure is available online.

FIG. 4.—Paratype (ZUFMS-REP 2291) of Helicops nentur sp. nov. immediately postmortem in (A) dorsal view and (B) ventral view. A color version of this figure is available online.

FIG. 5.—Locality records of Helicops nentur sp. nov. in the state of Minas Gerais, Brazil (insert). A color version of this figure is available online.

FIG. 6.—Phylogenetic relationships of sampled species of Helicops based on (A) 16s rRNA and (B) C-mos sequence data. Numbers at nodes indicate the bootstrap values/posterior probabilities; the bars below each cladogram indicate base substitution rate for each gene (# of substitutions per site). Hŋdrops triangularis and Pseudoerŋx plicatilis were used as outgroups.