The following species are recognized in the genus Plectrohyla: Spikethumb frogs range from 44 to 90 mm in adults, and have thick, glandular skin.

[5] Plectrohyla have an enlarged prepollex, which is a rudimentary additional digit near the thumb, that contains a sharp projecting spine.

[5] The premaxilla is a bone in the anterior portion of the skull that has a bony outgrowth called the alary process, which projects posteriorly and divides into two branches.

[6] Secondary sex characteristics in males include elongated premaxillary and maxillary teeth, in addition to swelling of the upper lip during breeding.

[5][7] Characteristics of these streams include many rocks, crevices, small waterfalls, and a current to maintain water oxygenation levels.

[7] Species of Plectrohyla remain near these streams year-round, often utilizing the same rock crevices for feeding and reproduction.

[10] In Plectrohyla, the specialized mucous glands in the lips of males produce sodefrin precursor-like factors (SPF), which function as allohormones.

[8] This copulatory mechanism resembles the condition of the plethodontid salamander, in which males use their elongated teeth to scratch the backs of females to deliver allohormones directly from the mental glands on their chin.