Brachypelma
Brachypelma is a genus of spiders in the family Theraphosidae (tarantulas). They may have bodies up to 6 cm (2+1⁄4 in) long with legs of similar or greater lengths. Some species have brightly colored legs, with red or orange marks and rings.
The taxonomy of the genus and its species has been the subject of considerable debate. In 2020, the genus was split, with a group of species (the "red rump" tarantulas) being moved to a new genus, Tliltocatl. As now circumscribed, the genus Brachypelma is found only in Mexico. Many species of both genera are popular with tarantula keepers as pets; the females in particular are long lived. All species are protected, and trade is regulated under CITES. Although they are bred in captivity, they continue to be exported in large numbers. Members of the reduced genus Brachypelma (the "red leg" group) are considered to be in most urgent need of further conservation efforts.
Members of the family Theraphosidae, the tarantulas, to which Brachypelma belongs, are generally large compared to other spiders, and are commonly seen as "objects of dread". Tarantulas do not use webs for capturing their prey, relying on their venom and their size and strength.[3] Brachypelma species are noted for their large size, colorfulness and docility in captivity.[4] Larger species of Brachypelma, such as B. smithi, have body lengths in the approximate range 45–60 mm (1+3⁄4–2+1⁄4 in) with legs up to 70 mm (2+3⁄4 in) long. Females on average have longer bodies than males but shorter legs.[5]
Species have bright red markings on their legs. B. boehmei has been described as the "most gorgeous" species of the genus.[4] The parts of the legs closest to the body are black, then three segments (the patellae, tibiae and metatarsi) are bright orange-yellow, followed by black tarsi. Although brightly colored, Brachypelma species are cryptic when in their native habitat.[6]
The distribution of hairs on the legs and palp and the shape of the male and female genitalia are the diagnostic features of the genus. In common with species of Tliltocatl, the prolateral (forward facing) surface of the trochanter and femur of the first leg and the retrolateral surface of the pedipalp have plumose hairs, and there is no pad of plumose hairs on the femur of the fourth leg. The male palpal bulb has a flattened, spoon-shaped embolus; females have fused spermathecae, with a flat cross-section.[7] Brachypelma can be distinguished from Tliltocatl by presence of the red or orange patterns on the legs of all species except B. albiceps, which can be recognized by the golden yellow carapace. Brachypelma species lack spines on the patellae of the pedipalps and legs, unlike Tliltocatl species. The shape of the genitalia differs between the genera; the apex of the male palpal bulb is shorter in Brachypelma and the female spermatheca baseplate is more strongly developed and hardened.[8]
All the species of Brachypelma that have been studied in detail live in burrows. These have a single entrance, a little larger than the spider, opening into a horizontal tunnel that usually leads to two chambers: one where it molts and one where it rests and consumes its prey. The entrance is blocked with material, such as soil and leaves, bound together by silk when the spider is inactive for significant length of time; otherwise the entrance is open with some silk visible.[6] North American tarantulas like Brachypelma are "sit and wait" predators, seizing prey passing by the burrow entrance.[9]
