As night stretched across central Vietnam, a "large" creature with a heart-shaped tongue waited in the water of a stream. Its "dark green" eyes scanned the nearby forest, but it wasn't the only one searching.

Passing scientists spotted the "robust" animal - and discovered a new species.

Researchers hiked into the forests of Quang Binh and Thua Thien Hue provinces in 2015 and 2017 to survey wildlife, according to a study published June 5 in the peer-reviewed journal ZooKeys.

During their visits, the team encountered a few vaguely familiar-looking frogs, the study said. But when they took a closer look at the animals, they noticed several distinct features and realized they'd discovered a new species: Quasipaa binhi, or Binh's spiny frog.

A Quasipaa binhi, or Binh's spiny frog.

Binh's spiny frogs are considered "large," reaching almost 5 inches in length, the study said. They have "very stout" bodies with "rough" skin and "short" arms. Their toes are "swollen" on the tips. Their "enlarged" heads have "dark green" eyes, spines on the upper lip and heart-shaped tongues.

Photos show the new species. Seen from above, the frog is dark brown with slightly paler sides and fingers. Seen from below, its belly is white with a brownish-white throat and dark brown hands and feet.

A Quasipaa binhi, or Binh's spiny frog, as seen from below.

Binh's spiny frogs were found near forest streams between elevations of about 1,000 to 2,500 feet, the study said. Much about their lifestyle and behavior remains unknown.

Researchers said they named the new species after their late "colleague and friend" Binh Van Nguyen "in recognition of his contributions on ecological research of amphibians in Vietnam."

Two Quasipaa binhi, or Binh's spiny frogs, seen from above and below.

So far, Binh's spiny frogs have been found in Quang Binh and Thua Thien Hue provinces of central Vietnam, the study said. The new species likely lives across the border in Laos.

The new species was identified by its body size, eye color, spines, skin texture, stomach coloring and other subtle physical features, the study said. DNA analysis found the new species had at least 2% genetic divergence from other related species.

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The research team included Cuong The Pham, Chung Van Hoang, Tien Quang Phan, Anh Van Pham, An Vinh Ong, Vien Hong Thi Nguyen, Thomas Ziegler and Truong Quang Nguyen.