Callipogon relictus is a species of longhorn beetle which is mostly found in Korea, but also in China and southern part of Russian Far East. It inhabits mixed and deciduous forests. The population of Callipogon relictus is decreasing due to deforestation and uncontrolled collection, and therefore the species are listed in the Russian Red Book (category II).
The larvae of Callipogon relictus develop in the drying deciduous trees. The process takes 4 to 6 years, and the same tree can be populated by larvae several times a year. Larvae bring along spores of the fungus Pleurotus citrinopileatus, that contributes to degradation of the tree. With the length reaching up to , Callipogon relictus is the largest beetle of Russia. Larvae of different longhorn beetles can coexist in the same tree, such as Callipogon relictus, Rosalia coelestis, Leptura thoracica, Rhabdoclytus acutivittis, Anoplodera cyanea and several other species.
Systematics
The beetle is a relict and the sole representative of the tropical genus Callipogon in the fauna of the Old World – other species of this genus inhabit Central and South America. The divergence between Callipogon relictus and other species in the genus is estimated to have occurred around 34 million years ago, around the Eocene/Oligocene boundary, during the Early Eocene Climatic Optimum. Callipogon relictus was described in 1898 by the Russian entomologist Andrey Semyonov-Tyan-Shansky (who wrote his last name as Semyonov until 1906). He distinguished the new species from the other species of the genus by the following features: Extended rear part, that makes antennae shorter relative to the body size, Shorter and almost hairless upper jaws Edges of the prothorax are not jagged but bear spines, Eyes are closer together. These features were later interpreted as a sign of higher evolutionary development of Callipogon relictus compared to other species of its genus, but a more recent phylogenetic study found that the species is nested within the phylogeny of the genus, being closely related to species found from Colombia to Mexico.
Distribution
In Russia Callipogon relictus inhabits Amur Oblast, to the south and south-east of the town Raychikhinsk. It is also common in the Khingan and Norsk reserves, in the south of Khabarovsk Krai (south from Khabarovsk city), Jewish Autonomous Oblast and Primorsky Krai. The northernmost observation was reported near the village of Ekimchan in Amur Oblast. Outside Russia the beetle occurs in north-eastern China, North Korea and South Korea. It is expected that its distribution will increase to the north with climate change.
Description
Adults
Developed body (imago) is black, with brown elytra and brown-black feet; there are two pairs of bright spots of hair on pronotum. The size and shape of jaws and antennae varies among individuals. Antennae are dotted and rather long. Their first segment is short and thickened. The third segment is extended and is longer than the fourth and fifth segments combined. The fourth segment is equal or slightly longer than the fifth, and the 11th segment is longer than the first. The lower parts of third to tenth segments have spines.
Mandibles are two-toothed and are very large in males, longer than the head; they are much shorter in females. The upper side of the jaw is covered with coarse, wrinkled punctation, and the lower jaw and lower lip have thick shaggy orange felt. Pronotum is convex, with narrow spines on its sides; the spines are longer in females than males. Scutellum is densely covered with yellowish hairs. Elytra are very long, spotted and rounded at their top; they are more shining in males than in females.
Larvae, egg and pupa
Larvae are white, with black mandibles; the front half of pronotum has a transverse red stripe, which can have four narrow grooves. Larval body is massive, yellowish-white and covered with sparse, fine yellowish hairs. The head is strongly retracted into prothorax, epistoma is well delimited. Frontal sutures are distinct, longitudinal edges are sharply defined. Hypostome consists of two longitudinal sclerites, which are moved apart by the protruding regularly plate. Clypeus is small, transverse, whitish. Pronotum covers much of the head. The shield of pronotum is smooth at its front, and its back is densely covered with wrinkles. Thoracic legs are short, with long claws, covered with thick bristles.
The egg has an oval shape and is long. It is pink in the early stage, then darkens and turns black. The chorion of the egg has deep, thick, slightly faceted cells. The gaps between the cells are smaller than the cells themselves.