Bothrocophias, new genus

Type Species: Bothrops hyoprorus Amaral (1935), by present designation.

Etymology: The generic name is derived from the Greek words bothros, meaning pit, and kophias, meaning snake or adder; the gender of this name is masculine.

Content: The genus Bothrocophias contains four species: campbelli known only from the western slopes of the Ecuadorian Andes; hyoprora distributed throughout the western lowlands of the Amazonian rainforest; microphthalmus, found along the eastern versant of the Andes in Colombia, Ecuador, Peru, and possibly Bolivia; and a new species described below that is restricted to lowland rainforest in western Colombia (fig. 2).

Definition and Diagnosis: A lineage of crotaline snakes occurring in northern South America. Members of the four species included in this lineage are of moderate length, relatively stout-bodied, and terrestrial, lacking a prehensile tail. Females attain greater size than do males. The snout is weakly (B. campbelli and the new species described subsequently in this paper) to strongly (B. hyoprora and B. microphthalmus) elevated with a rostral scale that is approximately as high as broad or distinctly higher than broad. Dorsal coloration within the genus consists mainly of darker shades of brown and reddish-brown. A pattern of dorsal banding may be clearly evident or subdued, and in some specimens the bands do not meet evenly at the middorsal line and are staggered as large lateral blotches.

Derived characteristics shared by the four species of Bothrocophias include small, smooth intersupraocular scales; distinctive white spots on gular and infralabial scales; and tuberculate keels on scales on the caudal portion of the dorsum. Many, though not all, specimens of B. hyoprora and B. microphthalmus exhibit tiny scales between the rostral and internasals that have not been observed in any other New World pitviper.

There are 124–177 ventrals; 38–64 subcaudals, most of which are entire in B. hyoprora, but mostly divided in the other three species; 21–25 middorsal scale rows; 2–9 smooth intersupraoculars; 7–8 supralabials; 8–11 infralabials; 1–11 prefoveals; 1–3 canthals; and 3–4 interoculabials.

The osteology of the genus remains poorly known, though we have been able to examine one skull each of Bothrocophias hyoprora and B. microphthalmus. In these two species, the dorsal surface of the frontal bones is predominantly flat. The postfrontals are large, contributing more to the dorsal perimeter of the orbit than does the parietal. The posterolateral edges of the dorsal surface of the parietal bear a small lateral shelf of bone. The ectopterygoid has a single pit for the attachment of the ectopterygoid retractor muscle, is approximately equal in length to the base of the pterygoid, and has a broad, flat shaft. The choanal process is positioned medially on the palatine bone and is attenuate distally. The angular and splenial are partially fused, and the Meckellian foramen is divided by a thin extension of bone. Species of Bothrocophias have 4–5 palatine teeth, 12–15 pterygoid teeth, and 14–16 dentary teeth. The maxillary fang is approximately 1.5 times longer than the height of the maxilla.

We have seen hemipenes of Bothrocophias hyoprora and the species described in this paper. Hemipenes of these species are calyculate distally. Walls of the more proximal calyces are spinulate. Proximal to the calyces, small mesial spines and a moderate number (ca. 18–30 per lobe) of lateral spines are present. Though some lateral spines are noticeably larger than the mesial spines, none can be characterized as basal hooks. The hemipenes of B. hyoprora differ slightly from those of the new species in having longer and more slender lateral spines.

The following combination of characters diagnoses Bothrocophias from all other New World pitviper genera: (1) 7–8 supralabials; (2) small but unkeeled dorsal head scales, not arranged in a nine-plate, colubrid-like pattern; (3) tubercular keels on dorsal scales on posterior half of body; (4) white spots with dark borders on some gulars and infralabials; (5) 124–177 ventrals; (6) 4–5 palatine teeth; (7) 12–15 pterygoid teeth; (8) 14–16 dentary teeth; (9) maxillary fang approximately 1.5 times longer than height of maxilla; (10) mesial spines present on hemipenial lobes; (11) moderate number (ca. 18–30 per lobe) of lateral spines on hemipenes; (12) hemipenial lobes only slightly longer than organ's base; (13) choanal process of palatine attenuate distally; (14) ectopterygoid and base of pterygoid approximately equal in length; (15) dorsal surface of frontal bones predominantly flat; (16) postfrontal bones large, contributing more to dorsal perimeter of orbit than does parietal; (17) tail not prehensile and lacks a rattle.

Because the species of Bothrocophias have been previously included in the genus Bothrops, it is significant that skull morphology in the two genera is markedly different. In Bothrops (sensu stricto), including such species as B. asper and B. atrox, the skull is relatively narrow and elongate (Werman, 1992, 1999; Gutberlet, 1998a; Gutberlet and Harvey, in press), whereas the skull in Bothrocophias species is broad and heavily ossified. Specific characteristics that typify this divergence in skull morphology are (condition of Bothrops in parentheses): distance across frontals equal to (less than) width of skull at anterior end of supratemporals, shaft of ectopterygoid wide and flat (slender and round in cross section), and shaft of ectopterygoid equal to (greater than) length of base of pterygoid.

The holotype of Bothrocophias campbelli (INHMT 1956) is from Provincia de Chimborazo, Ecuador. As Campbell and Lamar (1992) noted, all specimens from Colombia previously assigned to B. campbelli possess a lower number of ventrals and coloration different from those from further south. These differences, in addition to others listed below, clearly indicate that the Colombian snakes represent a distinct species, and this may be known as

Bothrocophias myersi, new species

Holotype: American Museum of Natural History (AMNH) 109812 (original field number CWM 11878); an adult female (figs. 3, 4) from Quebrada Guanguí, 0.5 km above the Río Patia, Department of Cauca, Colombia, 100–200 m, collected by C. W. Myers and J. W. Daly, 16–17 February 1973.

Paratypes: All from Colombia: Cauca: Quebrada Guanguí, ca. 0.5 km above the Río Patia, 100–200 m (AMNH 107919–20); Valle del Cauca: Pacific coast on road Buenaventura–Río Calima (FMNH 165586–96); Caimancito, S of Buenaventura, on bank of Río Cajambre, 75 m (UTA R-21689); Buenaventura, near Río Raposo (USNM 151708, 154051).

Diagnosis: A moderately stout, terrestrial pitviper reaching a maximum known total length of 756 mm that may be distinguished from all other New World rattleless pitvipers by the following combination of characters: (1) 139–151 ventrals; (2) 44–52 divided subcaudals; (3) 21–23 dorsal scale rows at midbody; (4) prelacunal fused with second supralabial; (5) 3–6 smooth intersupraoculars; (6) 7 supralabials; (7) reddish-brown dorsal coloration in life; (8) distinctive white spots on some gular and infralabial scales.

Comparisons: Bothrocophias myersi and B. campbelli are easily distinguished from their Amazonian congeners by the presence of a lacunolabial (prelacunal not fused to second supralabial in B. microphthalmus and B. hyoprora). Additionally, B. hyoprora is the only member of the genus with undivided subcaudals. Bothrocophias myersi differs from B. campbelli in having fewer ventrals (139–151 vs. 162–177), fewer subcaudals (44–52 vs. 48–64), fewer intersupraoculars (3–6 vs. 6–8), and fewer prefoveals (1–2 vs 2–4). All known specimens of B. myersi except one (UTA R-21689, a small specimen with a banded pattern) have a distinctive brown-bronze dorsum in preservative, which differs from the distinctly banded dorsum of juvenile and adult B. campbelli. Because the holotype of B. myersi was reddish-brown in life and is now brown-bronze in preservative, we presume that all the brown-bronze specimens were reddish-brown in life. Table 1 summarizes additional variation among the four species of Bothrocophias.

Bothrocophias myersi is potentially sympatric with five pitviper species: Bothriechis schlegelii, Bothriopsis punctata, Bothrops asper, Lachesis stenophrys, and Porthidium nasutum (Campbell and Lamar, 1989; Zamudio and Greene, 1997). Bothriechis schlegelii and Bothriopsis punctata have prehensile tails (tail not prehensile in B. myersi). Also, B. schlegelii has undivided subcaudals and spinelike superciliary scales, and B. punctata has many more ventrals (175–213) than does B. myersi. Bothrops asper and Lachesis stenophrys attain considerably greater lengths and also have higher ventral scale counts (161–240 and >199, respectively). The twice-divided distal subcaudals of Lachesis are unique to that genus. Porthidium nasutum bears 24–41 undivided subcaudals, lacks a lacunolabial, has a rostral scale that is markedly higher than broad, and has fewer ventrals (123–145).

Description of Holotype: An adult female; rostral almost rectangular, but slightly wider ventrally, almost as wide as high (4.2 × 4.3 mm); nasal incompletely divided above naris, distinctly divided below naris; loreal single, bordered anterodorsally by larger canthal and by upper preocular posteriorly, longer than high; prefoveals 2/2; subfoveals absent; prelacunal fused to second supralabial; interoculabials 3/3; postfoveals 1/1, longer than high, extending posteriorly beyond posteroventral corner of pit, contacting lower preocular posteriorly and lacunolabial anteriorly; preoculars 3/3; upper preocular longer than high, contributing to canthus; middle preocular much shorter, contacting but not fused to supralacunal; lower preocular tiny, almost excluded from orbit by subocular and middle preocular; suboculars 1/1, each partially divided anteriorly; postoculars 2/2; supralabials 7/7; infralabials 9/9, first infralabial on left side partially fused to mental, first pair of infralabials barely contact each other medially; mental approximately as wide as long; chin shields longer than wide, contacting first four infralabials on each side; gulars between chin shields and first scale on underside of head that is wider than long 4/5; 4 internasals, middle two smallest and partially fused medially; canthals 2/2, anterior canthal distinctly larger, posterior canthal tiny, separating anterior canthal from supraocular; intercanthals 3, immediately posterior to internasals; intercanthals 5, between posterior canthals; intersupraoculars 6; all dorsal head scales, from level of posterior of supraoculars forward, smooth; supraoculars longer than wide but distinctly wider than adjacent intersupraoculars; dorsal scale rows 25–23–19; ventrals 148, ultimate scale in series extending only partially across venter; anal entire; subcaudals 48, all divided; tail spine slightly compressed laterally, curving slightly dorsad, as long as adjacent 3 subcaudals, tip blunt; dorsals extending onto tail spine only slightly farther than subcaudals; dorsal scales of middorsum at midbody twice as long as wide anteriorly, becoming wider posteriorly such that length only slightly exceeds width; dorsal body scales distinctly keeled, keel does not extend to terminus of scale, keels distinctly tuberculate on posterior portion of body; paraventrals smooth over most of body, very weakly keeled posteriorly, similar in size and shape to adjacent dorsals; parasubcaudals weakly keeled anteriorly, smooth posteriorly.

Measurements of holotype (in millimeters): SVL 597, TL 92, EP 1.7, EN 6.7, ED 3.9, HL 30.1, RH 4.3, RW 4.2.

In his field notes, Myers described the color in life of the holotype as follows: “Dark red-brown, posteriorly turning light blue-gray on sides. Pale grayish blue oblique lines from eye, and small spots of same color underneath head. Under head and venter orange, except turning white down center on posterior half of belly.” From our inspection of color slides of the holotype (AMNH 109812) taken before preservation, we can add the following: the dorsal coloration is almost uniform, but slightly darker bands are discernible against the red-brown ground color (fig. 3). From the supraoculars forward, the top of the head is dark brown, as is most of the side of the head. The iris appears to be red-brown, paler above.

Color in preservative (70% ethanol after 10% formalin): Dorsal surface of head unpatterned, pale brown to bronze in color; a wide, pale, brown-bronze postocular stripe extending from the posteroventral corner of eye to cover supralabial 7, all but anteroventral corner of supralabial 6, and posterodorsal edge of supralabial 5; pale postocular stripe bordered dorsally by a thin, dark brown stripe, and anteroventrally by a thicker stripe of same dark brown color; most of side of head and rostral dark brown, but with a small triangle of pale brown-bronze occupying anteroventral corner of supralabial 4 and posteroventral corner of supralabial 3; dorsum brown-bronze with a greater amount of dark brown or dark gray coloration laterally; most paraventrals partly dark gray-brown and partly cream-colored; no clear pattern discernible on dorsum; tail plain brown dorsally, darker than dorsal body coloration; ventral scales predominantly cream but also with a small amount of brown pigment, mostly concentrated laterally; subcaudals also cream but with slightly more brown pigment than ventrals; ventral surface of head cream but with distinctive coloration on several scales; mental and first 2 infralabials on each side dark brown; 5 infralabials on each side and a total of 8 gular scales containing white spots with irregular dark brown edges.

Variation: On each side of the head, specimens of Bothrocophias myersi have 1–2 prefoveals, 1–2 canthals, 3–4 interoculabials, 1 postfoveal, 3 preoculars, 1–3 suboculars, 1–2 postoculars, 7 supralabials, 8–10 infralabials, and 3–5 gulars between the chin shield and first ventral. Additional variation in features of scalation includes 3–4 internasals, 2–3 anterior intercanthals, 4–7 posterior intercanthals, 3–6 intersupraoculars (fig. 4), 21–26 anterior dorsal scale rows, 21–23 middorsal scale rows, 16–19 posterior dorsal scale rows, 139–151 ventrals, and 44–52 divided subcaudals. Coloration is similar in all type specimens, with the exception of one small male (UTA R-21689) with fairly distinct bands on the dorsum. Measurements (in millimeters) for specimens in the type series vary as follows. Males: total length 376–677, SVL 311–577, tail length 48–100. Females: total length 327–756, SVL 280–655, tail length 47–120. Table 1 summarizes variation within B. myersi.

Hemipenes: One paratype of Bothrocophias myersi (UTA R-21689) was preserved with its hemipenes everted. The total length of the right hemipenis is equivalent to the length of the first five subcaudals. The lobes bifurcate at a length of two subcaudals from the base, and the sulcus spermaticus divides at a distance approximately one subcaudal from the base. As in most other crotalines, the organ is spinous proximally and calyculate distally. There are 18–20 lateral spines per lobe, including 6–8 that are relatively large (approximately 1 subcaudal in length). Small mesial spines are also present on the proximal half of each lobe. The mesial spines extend as far distally as the lateral spines. The distal half of each lobe is entirely calyculate. Many of the proximal calyces have spinulate walls, but walls of the more distal calyces are smooth.

Distribution and Habitat: Bothrocophias myersi is known only from the Pacific lowlands (ca. 75–200 m) of Cauca and Valle del Cauca, Colombia. The original habitat in this region consists of very wet rainforest (probably >5000 mm of rain per year). Myers et al. (1978: 321–324) provided a detailed description and photographs of the habitat at the type locality. This type of habitat formerly occupied lowland areas of southwestern Colombia and adjacent areas in northwestern Ecuador. It is possible that B. myersi occurs (or used to occur) throughout the Chocó region, although we know of no records of this species from Ecuador. Unfortunately, extensive habitat destruction throughout the Ecuadorian Chocó region makes it unlikely that B. myersi currently occurs in that country.

Etymology: The specific epithet, a noun in the genitive case, is a patronym in honor of Dr. Charles W. Myers, who collected the new species and who has made many significant contributions to Neotropical herpetology through dedicated work in both the field and laboratory.