Sibon merendonensis, Rovito, Sean M., Papenfuss, Theodore J. & Vásquez-Almazán, Carlos R., 2012

Sibon merendonensis new species

(Figs. 2,3)

Holotype. Museum of Vertebrate Zoology ( MVZ) 263880, an adult female ( Fig. 2 View FIGURE 2. A ), collected at Finca la Bendición, 4.0 km SE (by road) of soccer field at junction with road to Pinalito, then 7.6 km E (by road) of La Trementina, 14.93042°N, 89.4167°W (WGS84 Datum), 1364 m, Departamento Zacapa, Guatemala, 16 January 2008, by Sean M. Rovito and Theodore J. Papenfuss. Original field number SMR 551.

Diagnosis. Sibon merendonensis is a member of the S. annulatus group as defined by Savage (2002) in having the penultimate supralabial separated from the eye by the lower postocular ( Fig. 3 View FIGURE 3 ). It differs from all other members of the S. annulatus group in having a scale row formula of 15–17–17 rather than 13–13– 13 in S. anthracops , 15–17– 15 in S. perissostichon , and 15–15– 15 in all other species in the group. Larger (TOL= 687 mm) than all other members of the S. annulatus group [female TOL range of 366 mm – 557 mm ( McCranie 2007)], except S. dimidiatus (maximum female TOL of ca. 800 mm) and S. perissisticon (TOL= 668 mm). Dorsal scale rows retain normal orientation vs. changing orientation from sides of body to dorsal midline in S. perissostichon . Table 1 (modified from McCranie 2007) compares S. merendonensis with all other members of the S. annulatus group.

Description of holotype. Adult female; large for a species of Sibon (SVL 498 mm; TOL 687 mm); tail short (TAL/TOL 0.275); head very distinct from neck ( Fig. 2 View FIGURE 2. A ); snout short, blunt in dorsal outline; rostral not extending posteriorly between internasals, short, two-thirds length of prefrontal suture; prefrontals long, their median suture 87% length of frontal; prefrontals bordering eye above loreal; frontal longer than wide, widest anteriorly, length two thirds that of parietals, in contact with prefrontals, supraoculars, and parietals; supraoculars longer than wide, equal in length to frontal; parietals long, wide, widest anteriorly, their median suture 20% longer than frontal; parietals in contact with frontal, supraoculars, upper postoculars, anterior and posterior temporals, and seven nuchal scales; nasal entire, in contact with first three supralabials, loreal, prefrontal, internasal, and rostral; loreal single, longer than high, its length less than one-half length of snout (tip of snout to anterior edge of eye) and one-half length of eye; loreal bordering eye; preoculars absent; subpreoculars absent; postoculars 2, upper wider than lower; temporals 1 + 2, anterior one above 7th supralabial, lower second on above 8th supralabial; supralabials 8, with 5th and 6th bordering eye (enlarged penultimate supralabial separated from eye by lower postocular); pupil vertically elliptical; eye length two times length of loreal; infralabials 8-8, first pair separated behind mental by a single, large postmental, infralabials 1-2 in contact with postmental, infralabials 2-5 in contact with anterior chinshields; anterior chinshields paired, longer than wide, longer than posterior chinshields; posterior chinshields paired, in broad contact medially; mental groove present. Fig. 3 View FIGURE 3 shows head scale characteristics discussed above. Ventrals 184; cloacal scute single; subcaudals 83; dorsal scales smooth, in 15 rows posterior to neck and 17 rows at midbody and anterior to cloaca, without apical pits or supracloacal ridges; vertebral row not enlarged anteriorly, barely enlarged posteriorly.

Color in life ( Fig. 2 View FIGURE 2. A ). Dorsal components of interspaces between bands very pale yellowish orange, with some cream-colored scales, brighter orange immediately behind head becoming paler posteriorly; dorsal components of bands medium brown. Lateral components of interspaces between bands mottled pale orange-brown; lateral components of bands cream-colored with brown mottling. Dorsal surface of head dark brown with orange mottling, orange patches condense into a stripe along midline posterior to parietals; supralabials brown with cream-colored mottling, sublabials mostly cream-colored with some brown. Iris golden-tan with darker brown flecks.

Color in alcohol. Rostrum medium brown, middle of dorsal surface of head whitish with a slight orange tint. Interspaces of bands whitish with orange tint and some brown speckling, bands medium brown dorsally, lighter brown and more speckled on sides of body. Venter pale yellowish cream color with brown speckling from underside of head to about one-third down body, paler than rest of venter. Middle third of venter yellowish grey with more brown speckling, posterior third of venter and anterior half of tail very pale orange cream color with brown speckling. Irregularly spaced small dark brown patches throughout venter. Bands do not continue across venter. Ventral surface of posterior half of tail is a nearly continuous irregular band of medium to light brown with some lighter speckling, thinner where interspaces meet venter.

Distribution and ecology. The holotype was found inside an arboreal bromeliad in broadleaf cloud forest with some pine trees. The type locality at La Montaña de las Granadillas is part of a belt of mid-elevation cloud forest stretching along a ridge to the vicinity of La Unión, Zacapa. Although the eastern part of this forest, near La Unión, has been sampled fairly extensively without the discovery of any additional specimens, we expect that this species occurs in other portions of the forested ridge. The forest where La Montaña de las Granadillas is located is separated from other areas of cloud forest by more arid lowland areas, including the arid Motagua Valley to the north. Given the isolated nature of this cloud forest, it seems unlikely that the species is found in other cloud forests in eastern Guatemala.

Etymology. The specific epithet makes reference to the Sierra del Merendón, the mountain range containing the type locality.