Relictual
Guides
Buemarinoidae
Buemarinoid Harvestmen
Buemarinoidae is a small family of harvestmen (Opiliones: Laniatores) comprising approximately six genera and six described species. The family belongs to the superfamily Triaenonychoidea, which contains over 440 species across four families. Buemarinoidae is considered an ancient, relictual lineage with a disjunct global distribution and a high prevalence of monotypic genera, suggesting significant historical extinction events.
Hexurella
dwarf funnel web spiders
Hexurella is a genus of dwarf funnel web spiders (Mygalomorphae, Hexurellidae) comprising some of the smallest mygalomorph spiders in the world. Adults measure 2.5–5 mm in body size. The genus represents a phylogenetically ancient, relictual lineage that diverged from other atypoids approximately 300 million years ago. As of 2026, the genus contains eight species, with four described in a 2023 taxonomic revision. Several species have highly restricted geographic ranges and may warrant conservation attention.
Hexurellidae
Micro Dwarf Tarantulas
Hexurellidae is a monogeneric family of mygalomorph spiders containing only the genus Hexurella, established in 2019 based on phylogenomic evidence showing it as sister to all remaining atypoids. This relictual lineage diverged from other atypoids approximately 300 million years ago. Members are among the smallest mygalomorph spiders worldwide (2.5–5 mm as adults), with seven recognized species distributed in the US-Mexico borderlands. The family exhibits strict microhabitat preferences and micro-endemism, making it significant for sky island biogeography research.
Hypochilus
North American lampshade spiders
Hypochilus is a genus of North American lampshade spiders (family Hypochilidae) comprising eleven described species, all endemic to the United States. The genus is a relictual lineage with a disjunct distribution across three montane regions: California, the southern Rocky Mountains, and the southern Appalachia. Hypochilus species exhibit extreme genetic divergence coupled with striking morphological conservatism, creating persistent challenges for species delimitation. These spiders are textbook examples of short-range endemics with naturally small geographic ranges and strict microhabitat specialization.
Hypochilus coylei
lampshade weaver
Hypochilus coylei is a lampshade spider described by Platnick in 1987 from the southern Appalachian Mountains of western North Carolina. It belongs to a relictual genus of microhabitat specialists with disjunct distributions across three North American montane regions. The species is sister to H. thorelli and exhibits extreme genetic divergence coupled with morphological stasis, characteristic of short-range endemic taxa with limited dispersal ability.
Hypochilus thorelli
Thorell's Lampshade-web Spider, lampshade spider
Hypochilus thorelli is a relictual spider species notable for possessing four book lungs—a trait shared with mesothele and mygalomorph spiders but unique among araneomorphs. The species constructs distinctive lampshade-shaped webs on the undersides of overhangs in humid Appalachian forests. First described by George Marx in 1888, it serves as the type species for both its genus and family. Its combination of primitive respiratory anatomy with derived silk-producing structures makes it significant for spider phylogenetics.
Inocelliidae
Square-headed Snakeflies, inocelliid snakeflies
Inocelliidae is a small family of snakeflies (order Raphidioptera) containing eight extant genera plus fossil taxa. Members are commonly known as square-headed snakeflies due to their distinctive head shape. The family is distributed across the Northern Hemisphere, with extant species found in temperate forests of Eurasia and North America. Inocelliidae are holometabolous predators with larvae that inhabit bark and wood of coniferous and deciduous trees, where they prey on other insects. The family includes notable fossil representatives such as Fibla carpenteri from Baltic amber, the largest known snakefly species.
Micromalthidae
Telephone-pole Beetles
Micromalthidae is an ancient, relictual family of beetles in the suborder Archostemata, represented today by a single extant species, Micromalthus debilis. The family has a fossil record extending to the Late Permian (approximately 260 million years ago), making it one of the oldest surviving beetle lineages. Members are characterized by highly unusual reproductive biology, including paedogenesis (reproduction by larvae) and parthenogenesis. The family shows extreme morphological reduction in adults, particularly males, with larvae serving as the primary feeding and persistent life stage.
Mymarommatidae
False Fairy Wasps
Mymarommatidae, known as false fairy wasps, comprise a minute family of parasitic wasps with approximately 20 described extant species across three genera (Mymaromma, Mymaromella, Zealaromma), plus numerous fossil species. These insects are among the smallest known wasps, measuring approximately 0.3 mm in length. For over a century, their biology remained enigmatic until 2022, when Mymaromma menehune was confirmed as a solitary endoparasitoid of barklice eggs (Psocodea: Lepidopsocidae). The family exhibits a distinctive relictual morphology, including a pleated head membrane and unique wing structure, and has been proposed as "living fossils" potentially related to the extinct Serphitoidea.
Omethinae
Omethinae is a small subfamily of click beetles within the family Omethidae, containing only the genus Omethus. These beetles are among the most obscure members of Elateroidea, with very few specimens known and limited biological data available. The group has been historically overlooked due to its rarity and the remote habitats of its constituent species. Current knowledge is based primarily on scattered museum collections rather than field studies.
Ropronia
Ropronia is a genus of parasitoid wasps in the family Roproniidae, a small and poorly known group within the superfamily Proctotrupoidea. The genus was established by Provancher in 1887 and represents one of the few extant genera in its family. Roproniidae are considered relictual wasps with limited species diversity and restricted geographic distributions. Members of this genus are rarely encountered and poorly represented in collections.