United States of America

Mammals living nowhere else include the Hawaiian Monk Seal (EDGE), the Red Wolf (ARKive), the Island Fox (ARKive), the Seminole Bat (Smithsonian), the Olympic Marmot (ARKive), the Utah Prairie Dog (ARKive), the Hopi Chipmunk (Smithsonian), Nelson’s Antelope Squirrel (ARKive), and the Giant Kangaroo Rat (ARKive). Representatives of endemic genera include the Pygmy Rabbit (Smithsonian), the Pale Kangaroo Mouse (ARKive), the Round-tailed Muskrat (Univ. Florida), the Red Tree Vole (ARKive), the Florida Mouse (flickr), and the Golden Mouse (Smithsonian).

Birds unique to the U.S. include the Gunnison Sage-grouse (ARKive), the Greater Prairie-chicken (ARKive), the Red-cockaded Woodpecker (Cornell), McKay's Bunting (ABA pdf file), the Nene (ARKive), and the Hawaiian Hawk (Audubon). Hawaii is exceptionally rich in endemic genera including the Palila (Native Birds of Hawai'i), the Oahu Amakihi (ARKive), the Akikiki (ARKive),the Iiwi (Audubon), the Akepa (BNA Online), the Maui Alauahio (BirdLife Int'l), the Akohekohe (Wikipedia), the Elepaio (ARKive), and the bird with the world's smallest natural range, the Nihoa Finch (BirdLife Int'l). The Kauai O'o (Wikipedia), which became extinct about 1987, was the last surviving member of an endemic family, the Mohoidae.

Reptiles restricted to the United States include the American Alligator (ARKive), the Panamint Alligator Lizard (CA Herps), the Blunt-nosed Leopard Lizard (CA Herps), the unisexual Plateau Striped Whiptail (CA Herps), the Island Night Lizard (nps.gov), the Pigmy Rattlesnake (Univ. Georgia), and the Eastern Diamondback Rattlesnake (FLMNH). Endemic genera include the Alligator Snapping Turtle (ARKive), the Diamondback Terrapin (neoTerrapin), the Florida Sand Skink (ARKive), and the Scarlet Snake (Univ. Georgia). The Florida Worm Lizard (Wormlizard.org) is the sole member of the family Rhineuridae.

Amphibians exclusive to the U.S. include the Alabama Waterdog (EDGE), the Houston Toad (TPWD), the Southern Cricket Frog (Univ. Georgia), the California Red-legged Frog (Sierra Forest Legacy), and the Eastern Spadefoot (AmphibiaWeb). Endemic genera include the Hellbender (hellbenders.org), the Southern Dwarf Siren (EDGE), the Red Salamander (Univ. Georgia), the Georgia Blind Salamander (ARKive), the slender salamanders (AmphibiaWeb), the Red Hills Salamander (EDGE), and the recently described Patch-nosed Salamander (ARKive). The torrent salamanders (ARKive) and the amphiumas (Caudata Culture) represent endemic amphibian families.

An impressve endemic freshwater fish fauna includes the Apache Trout (AZGFD), the Guadalupe Bass (Texas State Univ.), the Shortnose Gar (ADW), the Shovelnose Sturgeon (FishBase), the American Paddlefish (ARKive), the Redband Darter (ARKive), and the Devil’s Hole Pupfish (ARKive). Representing endemic families are the Alabama Cavefish (ARKive), the Pirate Perch (flickr), and the Everglades Pygmy Sunfish (FLMNH). Hawaii is especially rich in endemic marine fish including Potter’s Angelfish (Keoki & Yuko Stender), the Hawaiian Turkeyfish (eol), and the Hawaiian Garden Eel (eol). Mainland endemic marine fish include the Six-spot Prickleback (metridium.com), the Bull Sculpin (Cold Water Images), the Seaboard Goby (gobiidae.com), and the Striped Blenny (FishBase).

Endemic invertebrates include the Diana Fritillary (Butterflies of America), the Pacific Clubtail (Discover Life), over 1000 Hawaiian fruit flies (Edwards Lab), and a Hawaiian land snail Achatinella mustelina (ARKive). The U.S. is first in the world in endemic species of several freshwater groups: stoneflies (mt.gov), mayflies (Maine.gov), caddisflies (mt.gov), crayfish (MDC), mussels (MN DNR), and freshwater snails (FWGNA). A notable endemic cave fauna includes the Kretschmarr Cave Mold Beetle and the Tooth Cave Spider (both at TPWD), the Texas Cave Shrimp (ARKive), and a planarian Macrocotyla glandulosa (p. 20 of Biospeleology pdf file). Endemic Hawaiian marine invertebrates include the Finger Coral (Keoki & Yuko Stender), the Banded Ribbon Worm (Keoki & Yuko Stender), and a conesnail Miliariconus abbreviatus (Eddie Hardy). Only Australia has had more endemic invertebrate families described - representatives include a false stag beetle Diphyllostoma (BugGuide), a silverfish Tricholepidion (ADW), a spider Trogloraptor (Wikipedia), the land snails Amastra (ARKive) and Megomphix (CalPhotos), and a plethora of millipedes including Floridobolus (Alessandro Catenazzi), Eurymerodesmus (BugGuide), Chelojulus (NADIPLOCHILO), and Paeromopus (BugGuide).

Vascular plants found only in the U.S. include the Giant Sequoia (ARKive), the Bristlecone Pine (ARKive), the Baldcypress (Univ. Florida), the Flame Azalea (NPIN), the Venus Flytrap (ARKive), the Cobra Plant (Carnivorous Plants), the Texas Snowbells (CPC), the Scrub Blazing Star (flickr), the Pallid Manzanita (CBD), the Yellow Mock Aster (Calflora), the Canelo Hills Ladies’ Tresses (CBD), the Winkler Pincushion Cactus (UCDC), the Hawaiian Silversword (ARKive), the Olulu (Smithsonian), the Oha Wai (ARKive), the Aku (ARKive), and the Na’ena’e (CBD). Corkwood (CPC) is sometimes placed in an endemic family, the Leitneriaceae.

The U.S. includes parts of three biodiversity hotspots: the Madrean Pine-Oak Woodlands (CI), the Polynesia-Micronesia (CI), and the California Floristic Region (CI). Other important areas for endemic species include the Appalachian Mixed Mesophytic Forests (EoE), the Mississippi Piedmont Rivers and Streams (WWF), and the Hawaiian Marine (WWF).

See also American Samoa, Baker Island, Guam, Howland Island, Johnston Atoll, Midway Islands, Navassa Island, Northern Mariana Islands, Puerto Rico, United States Virgin Islands, and Wake Island.