Phrynosoma, whose members are known as the horned lizards, horny toads, or horntoads, is a genus of North American lizards and the type genus of the family Phrynosomatidae. Their common names refer directly to their horns or to their flattened, rounded bodies (squat bodied), and blunt snouts.

The generic name Phrynosoma means "toad-bodied". In common with true toads (amphibians of the family Bufonidae), horned lizards tend to move sluggishly, often remain motionless, and rely on their remarkable camouflage to avoid detection by predators. They are adapted to arid or semiarid areas. The spines on the lizard's back and sides are modified reptile scales, which prevent water loss through the skin, whereas the horns on the head are true horns (i.e., they have a bony core). A urinary bladder is absent. Of the 21 species of horned lizards, 15 are native to the US. The largest-bodied and most widely distributed of the American species is the Texas horned lizard.

Biology

Rain-harvesting

Like the unrelated thorny devil (Moloch horridus) which also lives in arid environments, some species of horned lizards exhibit a behaviour known as "rain-harvesting". As rain falls on the scales of a lizard's back, water is passively transported through channels to its mouth by capillary action. The extent of this ability varies between species of horned lizards.

Defenses

Horned lizards use a variety of means to avoid predation. Their coloration generally serves as camouflage. When threatened, their first defense is to remain motionless to avoid detection. If approached too closely, they generally run in short bursts and stop abruptly to confuse the predator's visual acuity. If this fails, they puff up their bodies to cause them to appear more horned and larger so that they are more difficult to swallow.

To avoid being picked up by the head or neck, a horned lizard ducks or elevates its head and orients its cranial horns straight up, or back. If a predator tries to take it by the body, the lizard drives that side of its body down into the ground so the predator cannot easily get its lower jaw underneath.

Blood-squirting

At least eight species (P. asio, P. cornutum, P. coronatum, P. ditmarsi, P. hernandesi, P. orbiculare, P. solare, and P. taurus) are also able to squirt an aimed stream of blood from the corners of the eyes for a distance up to .

Fire ants (Solenopsis invicta), introduced from South America via the nursery industry's potted plants, pose a significant threat to all wildlife including horned lizards. Phrynosoma species do not eat fire ants. Fire ants kill many species of wildlife, and are fierce competitors against the native ants, which horned lizards require for food (with their specialized nutritional content). Fire ants, and human attempts to eradicate ants, including invasive species and the native species on which the lizards prey, contribute to the continued displacement of native ant species and the decline of horned lizards.

Species and subspecies

The following 21 species (listed alphabetically by scientific name) are recognized as being valid by the Reptile Database, three species of which have recognized subspecies:

{| class="wikitable"

|-

! Image !! Common name !! colspan="2" | Scientific name !! style="width: 200pt;" | Distribution

|-

|200x200px||Giant horned lizard || colspan="2" | Phrynosoma asio <br /> ||southern Mexico

|-

| ||Baur's short-horned lizard || colspan="2" | Phrynosoma bauri <br /> <br />(disputed, may be conspecific with P. hernandesi) ||United States (southern Wyoming and Nebraska south through eastern Colorado to northern New Mexico)

|-

|200x200px||San Diego horned lizard,

Blainville's horned lizard

| colspan="2" |Phrynosoma blainvillii <br /> ||United States (southern and central California), Mexico (northern Baja California)

|-

|200x200px||Short-tailed horned lizard || colspan="2" |Phrynosoma braconnieri <br /> || Mexico (Puebla and Oaxaca)

|-

|200x200px ||Great Plains short-horned lizard || colspan="2" | Phrynosoma brevirostris <br /> <br />(disputed, may be conspecific with P. hernandesi) || Canada and the United States

|-

| frameless|200x200px||Cedros Island horned lizard || colspan="2" | Phrynosoma cerroense <br /> || Mexico (Cedros Island)

|-

|200x200px||Texas horned lizard || colspan="2" |Phrynosoma cornutum <br /> ||United States (southeast Colorado, central and southern areas of Kansas, central and western areas of Oklahoma and Texas, southeast New Mexico, and extreme southeast Arizona), Mexico (eastern Sonora, most of Chihuahua, northeast Durango, northern Zacatecas and San Luis Potosí, and throughout most of Coahuila, Nuevo León, and Tamaulipas)

|-

|200x200px ||Coast horned lizard || Phrynosoma coronatum <br /> ||

  • Cape horned lizard, P. c. coronatum <br />
  • California horned lizard, P. c. frontale <br />
  • Central peninsular horned lizard, P. c. jamesi <br />

|| Mexico (Baja California Sur)

|-

| ||San Luis Valley short-horned lizard || colspan="2" | Phrynosoma diminutum <br> <br />(disputed, may be conspecific with P. hernandesi) ||United States (Colorado)

|-

| frameless|200x200px||Ditmars' horned lizard,

rock horned lizard

| colspan="2" | Phrynosoma ditmarsi <br /> || Mexico (Sonora), United States (Arizona)

|-

|200x200px||Pygmy short-horned lizard || colspan="2" | Phrynosoma douglasii <br /> ||northwestern United States and adjacent southwestern Canada

|-

| ||Sonoran horned lizard,

Goode's desert horned lizard

| colspan="2" | Phrynosoma goodei <br /> ||United States (Arizona) and Mexico (Sonora)

|-

|200x200px||Greater short-horned lizard || colspan="2" | Phrynosoma hernandesi <br /> || southwestern United States and northwestern Mexico

|-

|200x200px||Flat-tail horned lizard || colspan="2" | Phrynosoma mcallii <br /> ||United States and Mexico

|-

|200x200px||Roundtail horned lizard || colspan="2" | Phrynosoma modestum <br /> || United States (Texas, New Mexico eastern Arizona, southeastern Colorado), northcentral Mexico

|-

|200x200px||Mexican Plateau horned lizard,

Chihuahua Desert horned lizard

| Phrynosoma orbiculare <br /> ||

  • P. o. bradti <br />
  • P. o. cortezii <br />
  • P. o. dugesii <br />
  • P. o. orbiculare <br />
  • P. o. orientale<br />

||Mexico (Chihuahua, Durango, Morelos, Nuevo León, Puebla, and Veracruz)

|-

| frameless|200x200px||Desert short-horned lizard || colspan="2" | Phrynosoma ornatissimum <br /> <br />(disputed, may be conspecific with P. hernandesi) || Canada and the United States

|-

|200x200px||Desert horned lizard || Phrynosoma platyrhinos <br /> ||

  • Southern desert horned lizard, P.&nbsp;p. calidiarum <br />
  • Northern desert horned lizard, P.&nbsp;p. platyrhinos <br />

|| southern Idaho in the north to northern Mexico

|-

| ||Guerreran horned lizard || colspan="2" |Phrynosoma sherbrookei <br /> ||Mexico

|-

|200x200px||Regal horned lizard || colspan="2" | Phrynosoma solare <br /> ||Arizona and Mexico

|-

|200x200px||Mexican horned lizard || colspan="2" | Phrynosoma taurus <br /> ||Mexico (Guerrero and Puebla)

|-

|}

Note: In the above list, a binomial authority or trinomial authority in parentheses indicates that the species or subspecies was originally described in a genus other than Phrynosoma.

<gallery mode="packed" heights="100">

File:Coast Horned Lizard (9096387129).jpg|Blainville's horned lizard (P. blainvillii)

File:Texas horned lizard (Phrynosoma cornutum), Armstrong County, Texas, USA (28 April 2013).jpg|Texas horned lizard (P. cornutum), Armstrong County, Texas, US (28 April 2013)

File:HORNED LIZARD, COAST (phrynosoma coronatum) (6-14-08) cerro alto north ridge, slo co, ca -01 (2579107136).jpg|Coast horned lizard (P. coronatum), San Luis Obispo County, California, US (June 14, 2008)

File:09-035 Horned Lizard (Phyrnosoma coronatum) (3481418737).jpg|Coast horned lizard (P. coronatum) (25 April 2009)

File:Greater short-horned lizard on Seedskadee National Wildlife Refuge (27558656089).jpg|Greater short-horned lizard (P. douglassi brevirostre), Sweetwater County, Wyoming, US (15 June 2016).

File:Phrynosoma douglasii 4226.JPG|Pygmy short-horned lizard (P. douglasii), Washington, US (5 June 2014)

File:Mountain short-horned lizard (Phrynosoma hernandesi), Culberson County, Texas, USA (19 May 2018).jpg|Mountain short-horned lizard (P. hernandesi), Culberson County, Texas, US (19 May 2018)

File:Roundtail Horned Lizard (Phrynosoma modestum), Municipality of Tula, Tamaulipas, Mexico (15 August 2004).jpg|Round-tail horned lizard (P. modestum), Municipality of Tula, Tamaulipas, Mexico (15 August 2004)

File:Mountain horned lizard (Phrynosoma orbiculare orientale), Municipality of Miquihuana, Tamaulipas, Mexico (24 September 2009).jpg|Mountain horned lizard (P. orbiculare orientale), Municipality of Miquihuana, Tamaulipas, Mexico (24 September 2009)

File:Desert Horned Lizard in Mojave Desert.png|Desert horned lizard (P. platyrhinos), San Bernardino County, California, US (9 July 2019)

</gallery>

Symbol

Texas designated the Texas horned lizard (Phrynosoma cornutum) as the official state reptile in 1993. Wyoming’s state reptile is the “Horn Toad”, the greater short-horned lizard (Phrynosoma hernandesi).

The "TCU Horned Frog" is the mascot of Texas Christian University in Fort Worth, Texas. The "Horned Toad" is also the mascot for Coalinga High School in Coalinga, California. This school is located in Western Central California and its arid region is home to the San Diego Horned Lizard, which is protected. The City of Coalinga hosts an annual "Horned Toad Derby" on Memorial day weekend which features horned toad races, a carnival and parade.

<gallery>

File:Superfrog.jpg|The TCU mascot is commonly known as Super Frog to TCU fans and students. He is usually present at TCU sporting events.

File:HornedToad.png|Horned lizard on a necktie at El Paso, Texas, in 1940

</gallery>

References

  • Horned lizard skulls and info at Digimorph.org
  • Horned Lizard Conservation Society
  • Horned Lizards at UTexas.edu
  • Argentine ants linked to declines in coastal horned lizards
  • Horned Toads - A field study of Short-horned Lizards by students of Waterville Elementary School