A. Side and dorsal views of tail.
B. Horizontal section of head, showing Harderian gland and eye.
C. Horizontal section through right eye.
D. Horizontal section of left eye, showing pigmentation and lens.
E. Distal part of eye, showing layers of retina.
F. Proximal part of another eye, showing cyst.
Rhineura floridana, known commonly as the North American worm lizard, Florida worm lizard, graveyard snake, or thunderworm, is a species of amphisbaeninan in the family Rhineuridae. The species is the only member of the monotypic genus Rhineura, and is found primarily in Florida but has been recorded in Lanier County, Georgia. There are no subspecies that are recognized as being valid.
Rhineura floridana varies in total length (including tail) from 18–30 cm (7–12 inches). The head has a shovel-like snout that projects forward past the lower jaws, which is used for burrowing. The eyes are highly reduced and not visible externally. The limbs are absent and, as in other Amphisbaenia, the body is covered by scales arranged in rings giving the animal a worm-like appearance.
R. floridana is a burrower, preferring a soil, sand, or leaf mold substrate, and spending most of its time underground where it is safe from predators. It surfaces only when heavy rain or plowing forces it to evacuate its burrow. Because of the latter, it is sometimes called thunderworm. When disturbed, it retreats into its burrow tail-first.
The diet of R. floridana includes insects and earthworms, but it is an opportunistic feeder and will eat almost any invertebrate small enough to catch.
Reproduction in R. floridana is by laying eggs (oviparous).
This species, Rhineura floridana, is classified as Least Concern on the IUCN Red List of Threatened Species (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.
- Species Rhineura floridana at The Reptile Database www.reptile-database.org. Accessed 09 January 2020.
- "Rhineuridae". Integrated Taxonomic Information System. Retrieved 19 August 2007.
- "Rhineura floridana". Integrated Taxonomic Information System. Retrieved 19 August 2007.
- Goin CJ, Goin OB, Zug GR (1978). Introduction to Herpetology, Third Edition. San Francisco: W.H. Freeman and Company. xi + 378 pp. ISBN 0-7167-0020-4. (Rhineura floridana, p. 277, Figure 15-2).
- "Rhineura". Integrated Taxonomic Information System. Retrieved 19 August 2007.
- 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 6 September 2008.
- Rhineura floridana at the IUCN Red List. Accessed 6 September 2008.
- Baird SF (1858). "Description of New Genera and Species of North American Lizards in the Museum of the Smithsonian Institution". Proceedings of theAcademy of Natural Sciences of Philadelphia 10: 253-256. (Lepidosternon floridanum, new species, p. 255).
- Conant R (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. (illustrated by Isabelle Hunt Conant). Boston: Houghton Mifflin Company. xviii + 429 pp. + Plates 1-48. ISBN 0-395-19979-4 (hardcover), ISBN 0-395-19977-8 (paperback). (Rhineura floridana, p. 135 + Plate 13 + map 98).
- Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp., 47 Plates, 207 Figures. ISBN 978-0-544-12997-9. (Rhineura floridana p. 323, Figure 156 + Plate 30).
- Smith HM, Brodie ED Jr (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3 (paperback), ISBN 0-307-47009-1 (hardcover). (Rhineura floridana, pp. 132-133).
- Stejneger L, Barbour T (1917). A Check List of North American Amphibians and Reptiles. Cambridge, Massachusetts: Harvard University Press. 125 pp. (Rhineura floridana, p. 72).
- Westphal, Natascha; Mahlow, Kristin; Head, Jason James; Müller, Johannes (2019). "Pectoral myology of limb-reduced worm lizards (Squamata, Amphisbaenia) suggest decoupling of the musculoskeletal system during the evolution of body elongation". BMC Evolutionary Biology 19 (16).
- Zim HS, Smith HM (1956). Reptiles and Amphibians: A Guide to Familiar American Species: A Golden Nature Guide. (illustrated by James Gordon Irving). New York: Simon and Schuster. 160 pp. (Rhineura floridana, pp. 68, 155).