Rena Humilis
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''Rena humilis'', known commonly as the western blind snake, the western slender blind snake, or the western threadsnake, is a
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of snake in the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Leptotyphlopidae The Leptotyphlopidae (commonly called slender blind snakes or thread snakes) are a family of snakes found in North America, South America, Africa and Asia. All are fossorial and adapted to burrowing, feeding on ants and termites. Two subfamilies ...
. The species is
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to the southwestern United States and northern
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. Six subspecies are currently recognized, including the nominate subspecies described here.


Description

''Rena humilis'', like most species in the family Leptotyphlopidae, resembles a long
earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...
. It lives underground in burrows, and since it has no use for vision, its eyes are mostly
vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
. The western blind snake is pink, purple, or silvery-brown in color, shiny, wormlike, cylindrical, blunt at both ends, and has light-detecting black eyespots. The skull is thick to permit burrowing, and it has a spine at the end of its tail that it uses for leverage. It is usually less than in total length (tail included), and is as thin as an earthworm. This species and other blind snakes are
fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...
under low frequency
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
light ( black light).Hulse AC (1971). "Fluoresence in ''Leptotyphlops humilis'' (Serpentes: Leptotyphlopidae)". ''The Southwestern Naturalist'' 16 (1): 123-124. On the top of the head, between the ocular scales, ''L. humilis'' has only one scale ('' L. dulcis'' has three scales). Smith HM, Brodie ED Jr (1982). ''Reptiles of North America: A Guide to Field Identification''. New York: Golden Press. 240 pp. . (''Leptotyphlops humilis'', pp. 136-137).


Common names

Common names for ''R. humilis'' include western slender blind snake, western threadsnake, and western blind snake.


Geographic range

''R. humilis'' is found in the southwestern United States and northern
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. In the US it ranges from southwestern and
Trans-Pecos The Trans-Pecos, as originally defined in 1887 by the Texas geologist Robert T. Hill, is the portion of Texas that lies west of the Pecos River. The term is considered synonymous with Far West Texas, a subdivision of West Texas. The Trans-Peco ...
Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
west through southern and central
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
, southern
Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
, southwestern
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
, and southern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. In Mexico its distribution includes the
Mexican states The states of Mexico are first-level administrative territorial entities of the country of Mexico, which is officially named United Mexican States. There are 32 federal entities in Mexico (31 states and the capital, Mexico City, as a separate en ...
of
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
, Sonora, Sinaloa,
Nayarit Nayarit (), officially the Free and Sovereign State of Nayarit ( es, Estado Libre y Soberano de Nayarit), is one of the 31 states that, along with Mexico City, comprise the Federal Entities of Mexico. It is divided in 20 municipalities and its ...
, Jalisco,
Colima Colima (), officially the Free and Sovereign State of Colima ( es, Estado Libre y Soberano de Colima), is one of the 31 states that make up the 32 Federal Entities of Mexico. It shares its name with its capital and main city, Colima. Colima i ...
, Chihuahua, Durango, Coahuila,
Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...
, and San Luis Potosí. The type locality given is "Valliecitas, Cal." The type locality was restricted by Klauber (1931) to "vicinity of Vallecito, eastern San Diego County, California," and by Brattstrom (1953) to "the Upper Sonoran Life Zone of the Vallecito area".


Habitat and diet

''Rena humilis'' lives underground, sometimes as deep as , and is known to invade
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...
and
termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blatto ...
nests. Its diet is made up mostly of
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
s and their
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...
e and
eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
. It is found in deserts and scrub where the
soil Soil, also commonly referred to as earth or dirt Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty. Common types of dirt include: * Debri ...
is loose enough to work.


Subspecies


References


Further reading

*Adalsteinsson SA, Branch WR, Trape S, Vitt LJ, Hedges SB (2009). "Molecular phylogeny, classification, and biogeography of snakes of the Family Leptotyphlopidae (Reptilia, Squamata)". ''Zootaxa'' 2244: 1-50. * Baird SF, Girard CF (1853). ''Catalogue of North American Reptiles in the Museum of the Smithsonian Institution. Part I.—Serpents.'' Washington, District of Columbia: Smithsonian Institution. xvi + 172 pp. (''Rena humilis'', new species, p. 143). * Behler JL, King FW (1979). ''The Audubon Society Field Guide to North American Reptiles and Amphibians''. New York: Alfred A. Knopf. 743 pp. . (''Leptotyphlops humilis'', pp. 584–585 + Plate 457). * Boulenger GA (1893). ''Catalogue of the Snakes in the British Museum (Natural HIstory). Volume I., Containing the Families Typhlopidæ, Glauconiidæ...'' London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I-XXVIII. (''Glauconia humilis'', pp. 70–71). * Conant R (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition''. Boston: Houghton Mifflin. xviii + 429 pp. (hardcover), (paperback). (''Leptotyphlops humilis'', pp. 137–138, Figure 31 + Map 121). * Klauber LM (1940). "The Worm Snakes of the Genus ''Leptotyphlops'' in the United States and northern Mexico". ''Trans. San Diego Soc. Nat. Hist.'' 9: 87-162. * 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. . (''Rena humilis'', pp. 361–363, Figure 172). * Schmidt KP, Davis DD (1941). ''Field Book of Snakes of the United States and Canada''. New York: G.P. Putnam's Sons. 365 pp. (''Leptotyphlops humilis'', pp. 94–95). * Stebbins RC (2003). ''A Field Guide to Western Reptiles and Amphibians, Third Edition''. The Peterson Field Guide Series ®. Boston & New York: Houghton Mifflin. xiii + 533 pp. . (''Leptotyphlops humilis'', pp. 340–341 + Plate 42 + Map 128). * Stejneger L, Barbour T (1917). ''A Check List of North American Amphibians and Reptiles''. Cambridge, Massachusetts: Harvard University Press. 125 pp. (''Siagonodon humilis'', p. 73). * Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. 1,105 pp. (in 2 volumes). (''Leptotyphlops humilis'', pp. 43–50, Figure 12 + Map 7 on p. 39).


External links

*
iNaturalist page
{{Taxonbar, from=Q2700474 humilis Reptiles of the United States Reptiles of Mexico Taxa named by Charles Frédéric Girard Taxa named by Spencer Fullerton Baird Reptiles described in 1853