| Literature DB >> 35437410 |
Distribution and identification of the species in the genus Helicops Wagler, 1830 (Serpentes, Colubridae, Xenodontinae).
Yannis Schöneberg1,2, Gunther Köhler2.
Abstract
Background: The aquatic snakes of the genus Helicops are widely distributed throughout northern South America, but understudied concerning some aspects, including morphological traits and distribution. The most recent publication that provided an identification key to all species of Helicops is over 50 years old. This key is of limited value today since it includes taxa no longer recognised and lacks 8 of the 19 species currently recognised. There never was a publication trying to summarise distributional and morphological information of all species of Helicops. Most knowledge of these species is distributed throughout many small publications, such as short observation notes. New information: Here, we present distribution maps (point records), an identification key and comments on identification for all species in this genus. We base our results on a comprehensive literature review of over 300 scientific publications and own examinations. Our examinations comprise 190 specimens of 10 of the 19 currently recognised species and one Helicops sp. We report range extensions for the species H.danieli, H.infrataeniatus, H.leopardinus, H.pastazae and H.polylepis. Yannis Schöneberg, Gunther Köhler.Entities:
Keywords: annotated list; aquatic snakes; distribution maps; identification key; morphology; neotropics; pholidosis; taxonomy
Year: 2022 PMID： 35437410 PMCID： PMC8930936 DOI： 10.3897/BDJ.10.e69234
Source DB: PubMed Journal: Biodivers Data J ISSN： 1314-2828
Introduction
Materials and methods
Data resources
Taxon treatments
Diagnosis
Table 1.
Summarised results of the morphologic examination of 190 specimens. Abbreviations: N: Number of examined individuals; SVL: snout-vent length; TL: tail length; VE: ventrals; SC: subcaudals; SCK: presence of subcaudal keels; LO: loreals; PRO: preoculars; PSO: postoculars; AT: anterior temporals; PT: posterior temporals; SL: supralabials; SL+E: supralabials in contact with the eye; IL: infralabials; DSM: dorsal scale rows at mid-body; DKM: dorsal keels at mid-body; DSP: dorsal scale rows at posterior body; DKP: dorsal keels at posterior body; CL: cloacal plate; div: divided; IG: intergenials; NA: if nasal is divided; sdiv: semi-divided.; values in brackets show observations we rate as natural abnormalities, which are discussed in the respective species account. We rounded values to the third decimal place, lengths are in millimetres. See Suppl. material 1 for data of all specimens.
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| N | 47 | 11 | 5 | 2 | 57 |
| SVL ♂ | 229–420 | 414–570 | 409 | 460 | 157–489 |
| SVL ♀ | 145–680 | 280–810 | 163–620 | 575 | 136–600 |
| TL ♂ | 128–275 | 160–190 | 194 | 174 | 66–174 |
| TL ♀ | 30–325 | 90–203 | 62–185 | 185 | 45–194 |
| TL/SVL ♂ | 0.417–0.696 | 0.330–0.387 | 0.474 | 0.378 | 0.311–0.526 |
| TL/SVL ♀ | 0.185–0.922 | 0.235–0.321 | 0.271–0.380 | 0.323 | 0.209–0.462 |
| VE ♂ | 103–119 | 139–141 | 128 | 123 | 114–128 |
| VE ♀ | 104–125 | 128–146 | 131–139 | 131 | 113–130 |
| SC ♂ | 69–100 | 64–71 | 79 | 59 | 58–88 |
| SC ♀ | 58–92 | 51–59 | 60–81 | 50 | 49–74 |
| SCK | present | absent | absent | present | absent |
| LO | 1 | 1–2 | 1 | 1 | 0–3 |
| PRO | 1–2 | 1–2 | 1 | 1 | 1–2 |
| PSO | 2–3 | 2 | 2 | 1–2 | 2 |
| AT | 1–3 | 1 | 1 | 1 | 1–2 |
| PT | 2–4 | 1–2 | 2–3 | 3 | 1–3 |
| SL | 8–9 | 7–8 | 7–8 | 8 | 7–8 |
| SL+E | IV | IV, III–IV | IV, | IV | III, III–IV, |
| IL | 9–11 | 9–10 | 9–12 | 11–12 | 9–12 |
| DSM | 17–20 | 17–19 | 18–19 | 25–27 | 17–20 |
| DSM | present | present | present | present | present |
| DSP | 16-17 | 17 | 17 | 21 | 15–17 |
| DKP | present | present | present | present | present |
| CL | div | div | div | div | div |
| IG | absent | absent | absent | present | absent |
| NA | sdiv | sdiv | sdiv | sdiv | sdiv |
Table 2.
See description Table 1.
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| N | 44 | 12 | 1 | 7 | 4 |
| SVL ♂ | 217–495 | 165–305 | 415 | 170–235 | 328 |
| SVL ♀ | 139–620 | 98–438 | 149–407 | 195–356 | |
| TL ♂ | 114–194 | 68–125 | 250 | 86–98 | 118 |
| TL | 53–235 | 33–129 | 58–69 | 118–134 | |
| TL/SVL ♂ | 0.333–0.547 | 0.410–0.412 | 0.602 | 0.417–0.506 | 0,360 |
| TL/SVL ♀ | 0.313–0.557 | 0.295–0.432 | 0.219–0.463 | 0.376–0.400 | |
| VE ♂ | 110–129 | 114–116 | 130 | 123–126 | 122 |
| VE ♀ | 109–127 | 112–124 | 122–128 | 116–119 | |
| SC ♂ | 53–88 | 64–67 | 108 | 72–101 | 53 |
| SC ♀ | 56–88 | 49–70 | 78–88 | 62–67 | |
| SCK | absent | absent | present | absent | absent |
| LO | 0–2 | 0–2 | 1 | 1 | 1 |
| PRO | 1–2 | 1–2 | 1 | 1 | 2 |
| PSO | 1–2 | 2 | 2 | 2 | 2 |
| AT | 1–2 | 1 | 1 | 1–2 | 1 |
| PT | 1–3 | 2 | 2 | 2–4 | 2 |
| SL | 7–9 | 7–8 | 7 | 7–8 | 8 |
| SL+E | III–IV, IV, IV-V | III–IV, IV | IV | III–IV, IV | IV |
| IL | 9–11 | 9–11 | 10–11 | 10–13 | 11–14 |
| DSM | 18–19 | 17–20 | 23 | 23 | 23 |
| DSM | present | present | present | present | present |
| DSP | 16–19 | 15–19 | 16 | 19–21 | 19 |
| DKP | present | present | present | present | present |
| CL | div | div | div | div | div |
| IG | absent | absent | present | absent | variable |
| NA | sdiv | sdiv | sdiv | sdiv | sdiv |
Distribution
Figure 1a.
Figure 1b.Morphology remark
Figure 1c.
Figure 1d.
Figure 1e.
Figure 1f.
Figure 2a.
Figure 2b.
Figure 2c.
Figure 2d.
Figure 2e.
Figure 2f.
Figure 3a.
Figure 3b.
Figure 3c.
Figure 3d.
Figure 3e.
Figure 4.Distribution of . White circles represent literature reports. For the coordinates and references of the distribution points from literature, see Suppl. material 2.
Taxonomic remark
Table 3.
Pholidosis characters of the female specimen SMF 34035. Abbreviations: SVL: snout-vent length; TL: tail length; VE: ventrals; SC: subcaudals; presence of subcaudal keels (SCK); PRO: preoculars; PSO: postoculars; LO: loreal; AT: anterior temporals; NA: nasal; PT: posterior temporals; SL: supralabials; SL+E: supralabials in contact with the eye; IL: infralabials; DSM: dorsal scale rows at mid-body; DKM: dorsal keels at mid-body; DSP: dorsal scale rows at posterior body; DKP: dorsal keels at posterior body; CL: cloacal plate; IG: presence of Intergenials; Decimal values were rounded to the third decimal place, lengths are in millimetres. See Suppl. material 1 for data of all specimens.
| SVL | 365 | PT right | 2 |
| TL | 189 | PT left | 2 |
| TL/SVL | 0,518 | SL right | 8 |
| VE | 124 | SL left | 8 |
| SC | 75 | SL+E right | IV |
| SCK | absent | SL+E left | IV |
| PRO right | 1 | IL right | 10 |
| PRO left | 1 | IL left | 10 |
| LO right | 1 | DSM | 17 |
| LO left | 1 | DKM | present |
| PSO right | 2 | DSP | 17 |
| PSO left | 2 | DKP | present |
| AT right | 1 | CL | divided |
| AT left | 1 | IG | absent |
| NA | semi-divided |
Discussion
Taxonomic discussion
Geographical extensions
| 1 | Dorsum uniform or with longitudinal stripes |
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| – | Dorsum with blotches, spots or transverse bars |
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| 2 | Dorsum tan to dark brown with five rows of narrow light stripes, ventral cream with two uniform rows of dark brown to black semi-lunar marks |
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| – | Colouration not as above |
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| 3 | Venter cream or yellow with 2–3 rows of black semi-lunar marks, 9–10 infralabials, 128–141 ventrals in males and 128–148 ventrals in females |
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| – | Colouration and pholidosis not as above |
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| 4 | Nasal entire |
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| – | Nasal semi-divided |
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| 5 | Ventral body cream, with or without faint brown flecks |
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| – | Venter contrastingly checkered or with dark longitudinal stripes |
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| 6 | Dorsum uniform moss green, dorsal weakly keeled |
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| – | Venter cream or red with 1–3 dark stripes or darkly checkered or black with light spots or intermediate forms; dorsal strongly keeled; dorsum dark brown with pale brown stripes |
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| 7 | Dorsal scale rows at mid-body 17, reducing to 15 anterior to cloaca; 56 subcaudals in the single known male, 41–52 in females; dorsum uniform dark olive, dark brown or dark grey |
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| – | Dorsal scale rows at mid-body 25, reducing to 21 anterior to cloaca; 68 subcaudals in the single known male, unknown in females; dorsum greenish-copper brown with three longitudinal rows of dark, rectangular spots, venter light greyish-brown with two lateral rows of light orange spots |
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| 8 | Intergenials present |
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| – | Intergenials absent |
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| 9 | Nasal entire; 85–96 subcaudals in females, unknown in males; 25–28 dorsal scale rows at mid-body, reducing to 18–20 anterior to cloaca; dorsum light to medium grey brown with 4 alternating rows of relatively small dark spots |
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| – | Nasal semi-divided; 55–117 subcaudals in males, 51–97 in females; 19–29 dorsal scale rows at mid-body, reducing to 16–23 anterior to cloaca; colouration variable |
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| 10 | 55–67 subcaudals in males, 50–53 in females; dorsum grey brown with alternating light and dark circular blotches; northern South America |
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| – | 83–117 subcaudals in males, 50–97 in females; colouration variable |
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| 11 | 110–119 ventrals in males, 113–125 in females; subcaudal keels absent; dorsum greyish-tan with 3–5 rows of irregular dark blotches, the vertebral blotches larger than laterals, all 3 usually fused longitudinally; northern South America |
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| – | 121–142 subcaudals in males, 130–150 in females; subcaudal keels present; colouration variable |
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| 12 | Weak subcaudal keels present, 121–134 ventrals in males, 130–145 in females; 93–117 subcaudals in males, 72–97 in females; 23–25 dorsal scale rows at mid-body, reducing to 16–19 anterior to cloaca; ventral colouration cream with a series of dark crossbands or alternating checks, light ventral colour extending on to several dorsal scale rows; northern South America |
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| – | Subcaudal keels absent, 135–142 ventrals in males, 137–150 in females; 85–91 subcaudals in males, 67–73 in females; 21–23 dorsal scale rows at mid-body, reducing to 16 anterior to cloaca; ventral colouration cream with a lateral series of dark checks; eastern Andean foothills of Ecuador |
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| 13 | Subcaudal keels present |
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| – | Subcaudal keels absent |
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| 14 | 103–123 ventrals in males, 104–125 in females; 17–20 dorsal scale rows at mid-body |
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| – | 118–132 ventrals in males, 124–132 in females or, if fewer than 124 ventrals in males, then 21–22 dorsal scale rows at mid-body |
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| 15 | 19 dorsal scale rows at mid-body; dorsum with dark blotches; one anterior temporal; 71–86 subcaudals in males, 67–73 in females; 125–132 ventrals in males, 128–132 in females |
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| – | 21–24 dorsal scale rows at mid-body; dorsum with dark transverse bands; 2–3 anterior temporals; 79–103 subcaudals in males, 80–84 in females; 118–127 ventrals in males, 124–132 in females; northern Mato Grosso, Brazil |
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| 16 | Dorsum scale rows at mid-body 23–26, reducing to 17–21 anterior to cloaca; 71–101 subcaudals in males, 71–88 in females; 10–13 infralabials; venter dark with pale spots |
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| – | Dorsum scale rows at mid-body 19–22, reducing to 16–19 anterior to cloaca; 64–89 subcaudals in males, 53–76 in females; 8–11 infralabials; venter checkered or banded black and red or cream with two medial rows of black semi-lunar marks, sometimes fused mid-ventrally |
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| 17 | 19 dorsal scale rows at anterior and mid-body and 17–19 dorsal scale rows anterior to cloaca; dorsal scales with moderate keels; dark dorsal spots fusing to transversal bands |
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| – | Number of dorsal scale rows different |
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| 18 | Venter checkered or banded black and red; 108–129 ventrals in males, 108–138 in females |
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| – | Venter cream with two medial rows of black semi-lunar marks, sometimes fused mid-ventrally; 125–135 ventrals in males, 130–141 in females |
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Dichotomous identification key, based on our own examinations and literature (listed in Suppl. material 3).
3 in total
1. Contributions to the knowledge of amphibians and reptiles from Volta Grande do Xingu, northern Brazil.
Journal: Braz J Biol Date: 2015-08 Impact factor: 1.651
2. Long known, brand new, and possibly threatened: a new species of watersnake of the genus Helicops Wagler, 1828 (Serpentes; Xenodontinae) from the Tocantins-Araguaia River Basin, Brazil.
Journal: Zootaxa Date: 2021-01-07 Impact factor: 1.091
3. Chance, luck and a fortunate finding: a new species of watersnake of the genus Helicops Wagler, 1828 (Serpentes: Xenodontinae), from the Brazilian Pantanal wetlands.
Journal: Zootaxa Date: 2019-08-06 Impact factor: 1.091
3 in total