Micro-endemic
Guides
Anillinus tishechkini
Anillinus tishechkini is a small ground beetle species described in 2004 from the United States. It belongs to the tribe Anillina within Carabidae, a group characterized by reduced eyes and subterranean habits. The species is part of a genus containing numerous micro-endemic taxa in North America.
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.
Lepismadora algodones
Algodones Sand Jewel Beetle
Lepismadora algodones is a tiny jewel beetle (family Buprestidae) and the sole member of its genus. Described in 1987, it represents the most recently discovered new genus of jewel beetle in the United States. The species exhibits an extraordinarily restricted distribution, having been found only in a single old canal on the west side of the Algodones Sand Hills in southeastern California. Its closest known relative is the genus Eudiadora, known only from Argentina, indicating a remarkable disjunct biogeographic relationship.
Microhexura
Pygmy Funnel-web Spiders, spruce-fir moss spider (M. montivaga)
Microhexura is a genus of minute mygalomorph spiders endemic to North America, containing two described species: M. montivaga and M. idahoana. The genus represents the sole member of family Microhexuridae. M. montivaga, the spruce-fir moss spider, is restricted to high-elevation spruce-fir forests on isolated peaks in the southern Appalachians and is federally endangered. M. idahoana occurs in old-growth coniferous forests of the Pacific Northwest and northern Rocky Mountains. Both species inhabit moss mats and are among the smallest mygalomorph spiders.
Prionoglarididae
Large-winged Barklice
Prionoglarididae is a family of small, winged insects in the order Psocodea, commonly known as barklice or booklice. The family contains approximately 9 genera and over 20 described species distributed across Europe, Asia, Africa, and North America. Members are characterized by reduced or simplified lacinia (mouthpart structures) in adults and highly specialized male genitalia. The genus Neotrogla is notable for exhibiting sex-reversed genitalia, with females possessing an intromittent organ (termed a gynosome) and males having vagina-like structures. Most species inhabit cave environments.