While the mission would prove successful, the most significant find of the trip wasn’t a viper, or even reptile – and would turn up by pure luck some 70 km to the south.
After securing the second known specimen of Crotalus ericsmithi—Mexico’s rarest rattlesnake at the time—in the Sierra de Tecpan, the team went south to Guerrero’s highest peak, Cerro Teotepec at 3,550. Climbing the southwestern slopes produced a specimen of Brown’s Montane Viper (Ophryacus browni), and the team started down the northeastern versant. A quick stop, a few turned stones, and two tiny frogs elicited a: “well, that’s an undescribed species”. And as tradition seems to require: we’d sit on it for the next decade.
The Team was headed south again, chasing a tip on a potentially new species of frog that HERP.MX’s Jacobo Reyes Velasco had seen just a few years earlier. The plan was to take a road cutting through the Sierra Madre del Sur and survey for calling frogs along its length. While the target species would quickly prove to be a known frog (Eleutherodactylus albolabris), the team hit the brakes at a high elevation pass when a strange, unknown vocalization cut through the air. Despite an intense search, the team was only able to locate three specimens along the rocky hillsides and roadcuts – and while an initial assessment tentatively identified them as Guerreran Peeping Frogs, Eleutherodactylus dilatus, subsequent molecular analysis revealed that these tiny peeping frogs represented a novel species that, despite visits herpetologists from various institutions, had never been collected.
Additional trips, hundreds of measurements, and additional molecular analysis would later culminate in the description of two new peeping frog. We’re pleased to introduce the Spot-lipped Trilling Frog (Eleutherodactylus maculabialis) and the Balsamo Peeping Frog (Eleutherodactylus sentinelus) from the Sierra Madre del Sur in Guerrero.
The Spot-lipped Trilling Frog is a widespread species occupying approximately 150km2 on Cerro Teotepec in the Sierra Madre del Sur. The specific name, maculabialis, references this frog’s bright colored spots on its upper lip. The species appears to be common, and its multi-note “trill” is a abundant during the monsoon season.
The Balsamo Peeping Frog is known only from the vicinity of the type locality at the northwestern most extension of the Sierra Madre del Sur. It has been observed between 1300 and 1900m in elevation on steep mountain sides in humid pine-oak forest. The specific epithet is derived from the latin “sentinel”, a reference to the type-locality at the northwestern most point, and first outpost of the Sierra Madre del Sur in Guerrero.