Relict-species
Guides
Antrodiaetidae
folding-door spiders, folding trapdoor spiders, turret spiders
Antrodiaetidae is a small family of mygalomorph spiders comprising four genera and approximately 37 species. Members are commonly known as folding-door spiders or folding trapdoor spiders due to their distinctive burrow architecture: they construct silk-lined burrows with hinged, collapsible doors that fold or unfold to seal the entrance. The family is primarily distributed in the western and midwestern United States, with two relict species endemic to Japan. Antrodiaetidae are closely related to Atypidae (atypical tarantulas) and share the characteristic low dispersal ability typical of mygalomorph spiders.
Cyphoderris
Hump-winged Grigs
Cyphoderris is a genus of primitive orthopterans known as hump-winged grigs, representing a relict lineage of the ancient family Haglidae (now Prophalangopsidae). These cold-adapted, nocturnal insects are restricted to high-elevation coniferous forests and sagebrush meadows of western North America. Males produce acoustic signals by rubbing their forewings together to attract females. The genus exhibits unusual reproductive biology in which females feed on male metathoracic wing tissue during copulation, and males provide substantial proteinaceous spermatophores. Only three species are currently recognized: C. strepitans, C. buckelli, and C. monstrosa.
Cyphoderris monstrosa
Great Grig, Monster Haglid
Cyphoderris monstrosa is a relict species of hump-winged grig in the family Prophalangopsidae, one of only seven extant species in a family with over 90 known fossil species. This small orthopteran inhabits coniferous forests of western North America, where males produce high-pitched trilling calls at sundown to attract mates and defend territories. The species exhibits several unusual traits, including a unique mating ritual in which females feed on male hind wings during copulation, and dual sound-producing structures—males use tegminal stridulation while females and juveniles use the Ander's organ.
Cyphoderris strepitans
sagebrush cricket, sagebrush grig
Cyphoderris strepitans is a primitive orthopteran and one of few surviving members of the family Prophalangopsidae, a relict group known primarily from fossils. The species is endemic to the mountains of Wyoming and Colorado, where males produce loud calling songs by stridulation to attract females. A notable feature of its reproductive biology is sexual cannibalism during mating, where females consume the male's fleshy hind wings and hemolymph, and subsequently a proteinaceous spermatophore. Males experience significant energetic costs from this nuptial feeding, reducing their ability to call and remate. The species is cold-adapted and capable of singing at temperatures as low as -8°C.
Leiobunum relictum
Leiobunum relictum is a species of harvestman (order Opiliones) in the family Sclerosomatidae, described by Davis in 1934. The species name 'relictum' (meaning 'left behind' or 'relict') suggests a population isolated from formerly more widespread distribution. It is recorded from North America, though specific locality details and ecological data remain sparse in published sources.
Neduba sierranus
sierra shieldback
Neduba sierranus, the sierra shieldback, is a species of shield-backed katydid endemic to western North America. It belongs to a relict genus whose diversification reflects cycles of allopatric isolation and secondary contact in the tumultuous geological history of the region. The species was redescribed in a 2021 comprehensive revision of the genus Neduba using molecular phylogenetics, morphology, calling song analysis, and karyotypes. Like other Neduba species, it is flightless and characterized by a distinctive shield-like pronotum that extends backward over the abdomen.
Priacma serrata
Priacma bleach beetle
Priacma serrata is the sole extant species in the genus Priacma, a relict lineage of reticulated beetles in the family Cupedidae. Males are strongly attracted to the odor of bleach and other chlorine-based compounds, a unique behavioral trait that facilitates collection and study. The species exhibits pronounced sexual dimorphism, with females substantially larger than males and rarely encountered. Adult males possess non-functional digestive tracts and do not feed. Populations display episodic mass emergence events rather than continuous adult activity.
Protanyderus vipio
Protanyderus vipio is a species of primitive crane fly in the family Tanyderidae. The genus Protanyderus contains some of the most archaic members of the Diptera, retaining characteristics that reflect the early evolutionary history of true flies. This species was described by Osten Sacken in 1877. Very few observations of this species exist in public databases, suggesting it is either genuinely rare, poorly surveyed, or restricted to specific habitats.
Protoplasa fitchii
Protoplasa fitchii is a species of primitive crane fly in the family Tanyderidae. It is one of the few North American representatives of this relict family, which retains many ancestral dipteran characteristics. The species is primarily known from eastern North America, where larvae develop in aquatic or semi-aquatic habitats. Adults are rarely encountered and poorly studied.
Pytho
dead log beetles, dead log bark beetles
Pytho is a small genus of saproxylic beetles in the family Pythidae, commonly known as dead log beetles or dead log bark beetles. The genus comprises approximately nine to ten described species distributed across the Holarctic region, recognized as typically boreal taxa. Species inhabit the cambial layer of dead trees, particularly conifers, where larvae feed on partially decomposed wood and bark. Several species have disjunct distributions spanning North America, Europe, and Japan, reflecting complex historical biogeographic patterns involving vicariance and dispersal across Beringia. Some species, such as P. abieticola, are considered relicts of primeval forests and are in decline across much of Central Europe.
Rhysodidae
Wrinkled Bark Beetles
Rhysodidae is a family of saproxylic beetles comprising over 350 species in approximately 20 genera, predominantly distributed in tropical forests worldwide. The family contains three European species: Rhysodes sulcatus (Wrinkled Bark Beetle), Clinidium canaliculatum, and Omoglymmius germari. Members are obligate saproxylic beetles dependent on deadwood habitats, with most species being flightless, poorly mobile, and exhibiting cryptic habits. Rhysodes sulcatus is listed as Endangered in the EU-27 and serves as an umbrella species and bioindicator for ancient forest remnants.