Pyrearinus is a genus of click beetle (family Elateridae).
As one of the members of the tribe Pyrophorini, all species of this genus have luminous organs on their abdomen; among them, larvae of ' (described from Emas National Park, Brazil) are responsible for so-called "luminous termite hill" known to human beings at least since 1850.
Size variable (from 7 to 26 mm). Brownish or black; some species have a bicolorous prothorax (lateral margins yellowish or reddish and discal region darker). Pubescence dense, short and yellowish or not so dense and apparently absent. Eyes little prominent in males. Antennae short, serrate from the fourth segment onwards; second small, third a little longer, elongate and almost of the same length as the fourth. Prothorax more or less convex. Luminous spots flat or slightly convex, localized posteriorly; in species with bicolorous prothorax the spots are confused with the color of the integument. Punctures variable. Mesosternal cavity sinusoidal. plates tapering outwardly. Abdominal luminous organ small, sometimes indistinct. Male genitalia extremely homogeneous; median lobe tapering to apex; lateral lobe short. Female genitalia, more or less spiraled with a variable number of long spines; median oviduct with plates. Sexual dimorphism more or less , males with eyes larger than the females, and with longer antennae; in one species group (nyctolampis) the females have hind wings little shorter than usual.
The following list is based upon unless otherwise noted.