Atelopus mindoensis Peters 1973

Atelopus mindoensis

HOLOTYPE.—USNM 193554, from Mindo, Pichincha Province, Ecuador, 1200 meters, collected by Manuel Olalla, May 1959.

DIAGNOSIS.—A diminutive member of the longirostris group, most similar to A. palmatus, with adult females usually shorter than 30 millimeters in standard length. Males usually shorter than 20 millimeters. First digit on forefoot almost entirely hidden in webbing; ventral surfaces unicolor, no spotting, dorsum with a broad yellowish brown band and reddish brown spotting and marbling.

DESCRIPTION.—Snout from above bluntly pointed, with canthus forming straight line from tip of snout to nasal eminence, from that point to corner of eye it forms a gentle inward curve. Snout and edge of canthus fleshy anterior to nasal eminence, but no fleshiness on canthus from nostril to eye, on eyelid, or on temporal region. Slight depression in center of snout, as consequence of fleshy margin; rest of dorsum of head flat. Snout from side prominent, projecting over lower jaw; nostril closer to tip of snout than eye, on raised area and directed laterally; loreal region vertical, gently rounded, no loreal depression anterior to eye. Temporal region with scattered pustules and spines, differing in number and prominence between individuals. Body liberally studded dorsally and laterally with tiny pustules widely scattered but at least in part organized into tracts; scattered larger, pointed, usually pigmentless, rounded pustules along dorsolateral line and laterally; limbs also studded with tiny spicules, concentrated in raised, fleshy areas along length of limbs.

Forelimb slender in females, shorter and heavier in males, forefoot has somewhat fleshy webbing, with first digit completely covered by it, second digit included by a border of web; webbing deeply incised between second and third and between third and fourth digits, with fleshy nature of webbing making it appear absent between these three digits. No subarticular tubercles on slightly fleshy ventral surfaces of digits; plantar tubercle low, rounded, almost indistinct.

Hind limb slender, heel reaches to points between posterior margin of eye and axilla when hind limb is brought forward along body; heels touch or slightly overlap when tibiofibulae are parallel to femora at right angles to body. Webbing on foot extensive and somewhat fleshy, with first toe almost completely indistinguishable within it, second and third digits completely and continuously webbed; fourth toe webbed to tip, but webbing is hardly more than a border on ultimate phalanx; full webbing on fifth digit. Ventral surface of foot is devoid of tubercles; fairly large, raised, prominent, pigmentless outer metatarsal tubercle present.

COLOR IN ALCOHOL.—Dorsal ground color rather light yellowish brown, forming broad band length of back, filled with reddish brown marbling, spotting, and vermiculation in younger individuals, practically totally obscured in older individuals, which tend to have back almost unicolor reddish brown. Some individuals have irregular stripe from eye to groin, bordered below by lighter stripe beginning at posterior margin of orbit and disappearing on sides. Sides are usually reddish brown, sharply distinct ventrolaterally from belly color; some specimens have series of clear, yellowish spots on lower sides. Venter is clear light yellow, usually quite transparent, with eggs visible in body cavity of ripe females. Ventral surfaces of limbs often completely invaded by dorsal color, but in some individuals yellow of belly is continuous with yellow color of foot. No spotting of any sort on throat, belly, or soles, except in one female with few light brown spots on chin. Side of head dark brown, including upper lip; area below eye often with light yellow crescent. Lower jaw entirely yellow.

HOLOTYPE.—The holotype conforms with the description given above for the species, where no variation is mentioned. Where alternatives appear in the species description, the holotype has the following characteristics: temporal region with about six large, white-tipped pustules and many scattered spicules. Heel reaches to the posterior margin of the head when hind limb is brought forward; heels overlap slightly when tibiofibulae are parallel to femora at right angles to body. Dorsum almost unicolor, with irregular, somewhat lighter area dorsolaterally that is vermiculated on its inner margins. Clear yellowish spots present on lower sides, some fused with light yellow ventral color. Eggs visible in body cavity. Ventral surfaces of limbs dark brown, with few scattered lighter spots. Light crescentic area present below eye, lower lip with dark brown margin, rest of chin and throat clear. Measurements (in millimeters): snout to vent: 29.0; snout to end of coccyx: 27.2; knee to knee: 22.0; tibiofibula: 11.3; head length: 8.6; head width: 7.7; eye diameter: 4.0; snout to eye: 5.2; interorbital distance: 3.8; width of eyelid: 3.9.

ETYMOLOGY.—The species name is derived from the name of the type locality, a most pleasant little town where Beatriz Moisset and I spent several delightful days in the field in 1965.

SPECIMENS EXAMINED.—The following are paratypes: ECUADOR: Pichincha Province; Milpe, 900 m (USNM 193562–63), Mindo (BMNH 1968.115, UKMNH 108944–45, UMMZ 131684, USNM 193556–59), Río Blanco, near mouth of Río Yambi, about 700 m (CAS 134204, USNM 193561), Río Lelia (AMNH 79462), region below Sigchos (MCZ 84200, USNM 193564), Río Toachi(USNM 193555, 193560). The following are not designated as paratypes: ECUADOR: Esmeraldas Province; Carondolet (USNM 193570), Alto Tambo (BMNH 1968.116, USNM 193571–72, UPR–M 5092). Pichincha Province: Mindo (USNM 193565), region below Sigchos (USNM 193569), region of Gualea (USNM 193566–68), Tandayapa (GOV 8696, USNM 193573).

The Mindo stubfoot toad or Mindo harlequin-toad (Atelopus mindoensis) is a species of toad in the family Bufonidae. It is endemic to Ecuador in Pichincha, Santo Domingo and Cotopaxi Provinces. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests, and rivers. It has a unique appearance and color pattern, being green and red with white speckles, and due to this it was once considered an emblematic species of the Mindo Valley.

It is threatened by chytridomycosis and habitat loss, and was previously feared extinct, being last seen in Pichincha Province on May 7, 1989. It was not seen again for over 30 years, and any hopes for its survival and rediscovery were considered "unlikely", as the cloud forests it lived in were the most well-documented in the country. However, a remnant breeding population was discovered in 2019 in a privately owned cloud forest preserve, and this discovery was documented in 2020. This makes A. mindoensis one of the many members of its genus to be rediscovered in the 21st century following decades of no sightings.