Relict
Guides
Anaxyelidae
incense cedar wood wasps
Anaxyelidae is a relict family of siricoid wood wasps (Hymenoptera: Symphyta) represented today by a single extant species, Syntexis libocedrii, in western North America. The family was highly diverse during the Mesozoic, with over two dozen extinct genera and more than 50 fossil species documented from Jurassic and Cretaceous deposits across Asia, Europe, and North America. The family comprises two subfamilies: Anaxyelinae, which dominated the Jurassic, and Syntexinae, which prevailed in the Cretaceous and survives today.
Apystomyiidae
A small family of flies in the superfamily Asiloidea, containing one extant genus (Apystomyia) and two extinct genera (Apystomimus, Hilarimorphites). The sole living species, Apystomyia elinguis, is endemic to California. Extinct species are known from Late Jurassic to Late Cretaceous deposits in Kazakhstan, Myanmar, and New Jersey. Molecular studies place the family as sister to Cyclorrhapha within Eremoneura.
Connatichela artemisiae
Connatichela artemisiae is a monotypic weevil species endemic to the Yukon Territory, Canada, and the sole member of its genus. The species was described in 1984 and represents a distinctive lineage within the subfamily Entiminae, characterized by unique tarsal claw morphology. Fossil evidence indicates a broader Pleistocene distribution across Beringia, with modern restriction to the Yukon likely reflecting post-glacial habitat loss. Adults have been documented in association with small Artemisia species.
Cupes capitatus
Prominent-headed Reticulated Beetle
Cupes capitatus is the sole extant species in the genus Cupes, a relict lineage within the family Cupedidae. Described by Fabricius in 1801, this beetle represents one of the few living members of an ancient group of beetles with distinctive reticulated wing covers. Its restricted distribution in eastern North America and its phylogenetic isolation make it of particular interest for studies of beetle evolution and biogeography.
Euparagia
Euparagia is the sole extant genus of the subfamily Euparagiinae within family Vespidae. The group represents a geographically relict taxon with a formerly cosmopolitan distribution in past geological times, now restricted to desert regions of the southwestern United States and northwestern Mexico. The genus contains ten described species, most named by Bohart between 1938 and 1988. Biological knowledge is extremely limited; only Euparagia scutellaris has been studied, with females known to provision soil nests with weevil larvae.
Flohria
Flohria is a monotypic genus of rove beetles (Staphylinidae) containing a single species, Flohria subcoerulea. The genus was erected by David Sharp in 1884 and named in honor of collector Julius Flohr. Phylogenetic studies suggest it may occupy a basal position within the subtribe Philonthina, potentially representing a relict lineage.
Fumontana
Fumontana is a monotypic genus of harvestman (Opiliones: Laniatores) containing the single species F. deprehendor. It is considered an ancient relict lineage with Gondwanan affinities, currently restricted to the southern Appalachian Mountains of the eastern United States. The genus name derives from Latin words for 'smoke' and 'mountain', referencing its discovery in the Great Smoky Mountains.
Geopsammodius relictillus
relictual tiny sand-loving scarab
Geopsammodius relictillus is a small aphodiine dung beetle in the family Scarabaeidae, described from Florida in 1991. The species epithet "relictillus" refers to its relictual status, suggesting it may represent a remnant population of a formerly more widespread group. It belongs to the tribe Psammodiini, whose members are commonly known as sand-loving scarabs due to their association with sandy habitats.
Grylloblatta chirurgica
Mount Saint Helens Grylloblattid, Mount Saint Helens grylloblatid
Grylloblatta chirurgica is a species of ice crawler endemic to southwestern Washington state, specifically associated with high-elevation habitats and ice caves near Mount St. Helens in Skamania County. Described by Gurney in 1961, it is one of the rarest and most geographically restricted members of the relict order Notoptera (Grylloblattodea). The species persists in cold, stable microhabitats including glacial ice fields and subterranean ice formations. Its extremely limited distribution and specialized habitat requirements make it vulnerable to environmental change.
Grylloblattidae
ice crawlers, icebugs, rock-crawlers
Grylloblattidae, commonly known as ice crawlers or icebugs, is a family of wingless, cold-adapted insects representing the sole living family of the order Grylloblattodea. These relict insects inhabit extreme cold environments including glacier margins, alpine snowfields, caves, and subalpine forests across disjunct regions of the Holarctic. With approximately 35 extant species in six genera, they exhibit narrow physiological temperature tolerances and are considered endangered due to climate warming and habitat specificity.
Grylloblattodea
ice crawlers, rock crawlers
Grylloblattodea is a small order of extremophile insects commonly known as ice crawlers or rock crawlers. These wingless insects are adapted to cold environments and are found in montane habitats, caves, and subalpine forests across western North America and northeastern Asia. The order comprises approximately 25-30 described species in five extant genera, though significant undescribed diversity is suspected. Grylloblattids are predatory, feeding on other arthropods, and show remarkable cold tolerance. They are considered a relict lineage with ancient origins, closely related to Mantophasmatodea within the clade Xenonomia (order Notoptera).
Horologion
Horologion is one of the rarest and most enigmatic carabid beetle genera, containing two known species of troglomorphic ground beetles endemic to the middle Appalachian Mountains. The genus remained monotypic for over 60 years after its description in 1932, with a second species discovered in Virginia in 1991 and described in 2024. Phylogenetic analysis places Horologion in supertribe Trechitae as sister to the Gondwanan tribe Bembidarenini, making tribe Horologionini a relict lineage with no close relatives in the Northern Hemisphere.
Horologion hubbardi
Horologion hubbardi is a newly described species of carabid beetle from Bath County, Virginia. It represents only the second known species in the genus Horologion, which was previously known solely from a single holotype collected in West Virginia in 1931. DNA sequence data and morphological analysis place the genus in the supertribe Trechitae, as sister to the Gondwanan tribe Bembidarenini. The species is considered a relict lineage with no close relatives known in the Northern Hemisphere.
Hydrotrupes
Hydrotrupes is a genus of diving beetles (Dytiscidae: Agabinae) established by Sharp in 1882. The genus contains three species: two extant (H. chinensis in eastern China and H. palpalis in western North America) and one fossil (H. prometheus from Eocene Baltic amber). The fossil record establishes Hydrotrupes as at least 40 million years old and demonstrates remarkable morphological conservation over this timespan. The current disjunct distribution of living species is interpreted as a relict of a formerly widespread distribution across northern continents during the Eocene.
Jacobsoniidae
Jacobson's beetles
Jacobsoniidae is a small family of minute beetles within the superfamily Staphylinoidea, comprising three extant genera (Derolathrus, Sarothrias, Saphophagus) and approximately 28 described species. Adults and larvae inhabit cryptic microhabitats including leaf litter, rotting wood, fungal fruiting bodies, bat guano, and caves. The family exhibits remarkable morphological stasis since the Cretaceous, with fossil records from Cretaceous amber of Myanmar and France, Eocene Baltic amber, and Holocene copal. Members are among the smallest beetles, measuring 0.7–2.1 mm, and are exceptionally rare in collections.
Macroxyelinae
macroxyelid sawflies
Macroxyelinae is a small subfamily of sawflies within the family Xyelidae, one of the most basal lineages of Hymenoptera. The group contains two extant genera, Macroxyela and Megaxyela, with approximately six described species. These insects are characterized by their relatively large body size compared to other xyelid sawflies and their association with specific host plants, primarily hickories and walnuts (Juglandaceae). Macroxyelinae represents an ancient relict lineage with a primarily Holarctic distribution.
Melanthripidae
Melanthripidae is a family of thrips representing an early-diverging lineage within Thysanoptera. The family contains the genus Ankothrips, which has been identified as the most ancient extant thrips genus with remarkable morphological stability spanning approximately 94 million years. Fossil evidence from Cretaceous Spanish amber indicates members of this family were associated with gymnosperm pollen and likely served as pollinators of Ginkgoales during the Mesozoic era.
Merope
earwigfly, forcepfly
Merope is a genus of scorpionflies (Mecoptera) in the family Meropeidae, commonly known as earwigflies or forcepflies. The genus contains Merope tuber, the only living member of Meropeidae in North America. Males possess large segmented forceps-like cerci that resemble the pincers of earwigs. The family is exceptionally rare, with only three extant species described worldwide, and the immature stages remain unknown to science.
Merope tuber
forcepfly, earwigfly
Merope tuber is the sole species in the genus Merope and the only living member of the family Meropeidae in North America. The species occurs in eastern North America from Ontario to Georgia and west to Kansas, with recent records from Florida. Adults are nocturnal and secretive, rarely encountered due to their ground-dwelling habits. The species is notable for the large genital forceps present on male abdomens, which resemble the cerci of earwigs. Immature stages remain unknown, and much of the species' biology is poorly understood.
Omalonomus
Omalonomus is a genus of blind, wingless, lightly pigmented subterranean rove beetles in the family Staphylinidae. The type species Omalonomus relictus was described in 1990 from the Cypress Hills of Alberta-Saskatchewan, Canada. Its highly modified morphology reflects adaptation to a hypogeous lifestyle. The genus is considered a preglacial relict, supporting evidence for ice-free refugia in the Cypress Hills during Pleistocene glaciation.
Pelecinus
American pelecinid wasps, snake-tailed wasps
Pelecinus is the sole living genus of the family Pelecinidae, containing three species restricted to the New World. Females are immediately recognizable by their extraordinarily elongated, thread-like abdomens that can exceed 5 cm in length, used to probe soil and deposit eggs on scarab beetle larvae. The genus represents a relict lineage with extensive fossil diversity dating to the early Cretaceous across multiple continents.
Priacma
Priacma is a genus of reticulated beetles (family Cupedidae) containing one extant species, Priacma serrata, found in western North America. The genus also includes fossil species, notably P. megapuncta from Cenomanian-aged Burmese amber. Priacma represents one of the few surviving lineages of the once-diverse Archostemata, an ancient suborder of beetles. The genus was established by J. L. LeConte in 1874.
Prophalangopsidae
grigs, primitive katydids
Prophalangopsidae is the sole extant family of the ancient superfamily Hagloidea (Orthoptera). The family comprises a small number of relict species in North America and Asia, alongside numerous extinct genera known from Jurassic and Cretaceous deposits. Extant members are known as "grigs" in North America. The family diverged from its closest living relatives, the katydids (Tettigoniidae), over 230 million years ago during the Permian, making it one of the most phylogenetically isolated orthopteran lineages. Fossil evidence documents substantial diversity during the Middle Jurassic to Early Cretaceous, with sparse records thereafter.
Saltonia
Saltonia is a monotypic genus of North American cribellate araneomorph spiders containing the single species Saltonia incerta. The genus was first described in 1942 and has undergone several taxonomic revisions, most recently moved to the family Argyronetidae in 2025. It represents a rare relict lineage restricted to hypersaline desert habitats in southwestern North America.
Spanglerogyrus
Spanglerogyrus is a monotypic genus of whirligig beetles (family Gyrinidae) containing the single species S. albiventris. It represents the only living member of the subfamily Spanglerogyrinae, the earliest diverging extant lineage of gyrinid beetles. The genus was described in 1979 from specimens collected in southern Alabama, making it a rare example of a relictual aquatic beetle lineage in North America.
Superstitioniidae
Superstitioniidae is a monotypic family of scorpions containing only the genus Superstitionia and its sole species, Superstitionia donensis. The family is endemic to the southwestern United States and northwestern Mexico, where it inhabits rocky desert environments. It was established by Stahnke in 1940 and represents one of the most taxonomically restricted lineages within Scorpiones.
Synneuron
Synneuron is a rare genus of flies in the family Canthyloscelidae, with four extant species distributed across the Holarctic region. The genus has an exceptional fossil record extending back to the Lower Cretaceous (ca. 125 Ma), with specimens from Australia and the Eocene of North America, supporting its status as a true Pangean clade that survived major vegetation transitions from gymnosperm to angiosperm dominance. Its ancient origins and relictual modern distribution make it significant for understanding dipteran biogeography and the impact of Cretaceous floral turnover on insect lineages.
Syntexis
cedar wood wasp, incense-cedar wood wasp
Syntexis is a genus of wood wasps in the family Anaxyelidae, containing a single extant species, Syntexis libocedrii, often called a 'living fossil' due to the family's extensive Mesozoic fossil record. The genus is notable for its obligate association with fire-damaged conifers and its prolonged larval development in living tree wood. Syntexis represents one of the most relictual lineages among extant Hymenoptera.
Tanyderidae
Primitive crane flies
Tanyderidae, commonly called primitive crane flies, are a small family of long, delicate nematoceran flies with about 40 extant species. They represent a relict lineage within Diptera, retaining primitive wing venation including five complete branches of the radial vein. Adults are recognized by their spotted or mottled wings and are typically found near streams, often resting on vegetation or hanging beneath bridges. Larvae inhabit wet, decaying wood or sandy and gravelly stream margins. The family has an extensive fossil record dating to the Late Triassic, with numerous extinct genera known from amber deposits.
Xyelidae
Xyelid Sawflies
Xyelidae is a family of sawflies comprising approximately 80 extant species in five genera worldwide, with an extensive fossil record of over 120 species dating to the Triassic. It is the sole family in the superfamily Xyeloidea and represents the sister group to all other extant Hymenoptera, retaining numerous ancestral morphological features. Extant species are primarily distributed in boreal regions of the Northern Hemisphere, with a relict distribution pattern. The family is divided into two subfamilies: Xyelinae, associated with conifers, and Macroxyelinae, feeding on deciduous trees.