The Spider Named Treecko That Became Rathalos

Pokémon trivia dug up from scientific papers

Treecko, Grovyle and Sceptile all have real spiders named after them. But today, the Treecko spider has a different “family name” from its evolutions: Rathalos, the flagship monster of Monster Hunter.

Video in Japanese from our channel “Pokémon Trivia Mine”.

Scientific names are family name + given name

Every species has a two-part Latin name. The first part is the genus (like a family name) and the second part is the species (like a given name). Scientific names must use only the 26 letters of the Latin alphabet, so the Japanese name キモリ (Kimori) could not be used as it is – the researchers chose the English name, Treecko.

In 2021 the three spiders were described in the same paper as Anyphaena treecko, Anyphaena grovyle and Anyphaena sceptile. All three shared the family name Anyphaena.

Collected on the same day, in the same place

The spiders come from Hainan, a tropical island in southern China. The Grovyle spider was collected on Mount Wuzhi on 9 April 2009 – along with 115 males and 150 females. Two weeks later, on 23 April, the Sceptile and Treecko spiders were collected at Bawangling in the west of the island, by the same people, at the very same GPS coordinates.

The specimens then waited twelve years in the Institute of Zoology in Beijing before being named. The paper explains the names: these are forest-dwelling Pokémon from Pokémon Emerald, a good match for forest spiders. The same paper also named a spider after Pikachu, and one after Gollum.

Only the Treecko spider moved house

In 2022 the same researchers reviewed 28 Asian spiders and created a new genus: Rathalos. Only two species went into it – an old spider known since 1991, and the Treecko spider. Grovyle and Sceptile stayed in Anyphaena.

Spider genera are told apart mainly by the shape of their reproductive organs. Rathalos spiders have a special bump on the male palp, and the female’s plate is a triangle that is taller than it is wide. The Treecko spider had these features; the Grovyle and Sceptile spiders did not. So the name followed the Pokémon evolution line, but the bodies said the Treecko spider belonged to a different family.

Its name today is Rathalos treecko (Lin & Li, 2021). The brackets around the authors are the scientific way of saying “this species was first named in a different genus”.

“An arbitrary combination of letters”

The 2022 paper only says that Rathalos is an arbitrary combination of letters. But the researcher who named it, Lin Yejie, is a big Monster Hunter fan and has said on social media that he named it. In 2024 he also named an eyeless cave spider Otacilia khezu, after the blind Monster Hunter monster Khezu.

In March 2026, a spider from Java that lives inside dry bamboo was named Rathalos inagami, after Inagami, the bamboo-controlling Elder Dragon – and this time the paper says outright that the name comes from Monster Hunter. It was the first Rathalos spider found in Southeast Asia. So today, the Treecko spider’s relatives are not Grovyle and Sceptile, but an Elder Dragon.

The Pokémon in this story, in Japanese