The San Marcos gambusia (''Gambusia georgei'') is an extinct species of gambusia from the family Poeciliidae that was found only in the

San Marcos Springs San Marcos Springs is the second largest natural cluster of springs in Texas. The springs are located in the city of San Marcos, Texas, about 30 miles (48 km) southwest of Austin and 46 miles (74 km) northeast of San Antonio. Although ...

Central Texas Central Texas is a region in the U.S. state of Texas surrounding Austin and roughly bordered by San Saba to Bryan and San Marcos to Hillsboro. Central Texas overlaps with and includes part of the Texas Hill Country and corresponds to a ph ...

. The fish has not been seen since 1983. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

of this fish honors the American

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

George S. Myers George Sprague Myers (February 2, 1905 – November 4, 1985) was an American ichthyologist who spent most of his career at Stanford University. He served as the editor of ''Stanford Ichthyological Bulletin'' as well as president of the American So ...

(1905-1985).

Description

The San Marcos gambusia was typically less than 1.6 inches (4 cm) in length. It had a dark body with a slight blue tint, although the median fins were lemon yellow. The scales were strongly crosshatched, and the dorsal fin had a dark stripe along its edge. The species’ exact diet is not known, but other poeciliids typically eat insect larvae and other small invertebrates. The fish were live bearing and have been known to give birth to a few dozen young at a time.

Habitat

The San Marcos gambusia has only been identified in a 0.6-mile (1-km) stretch of the headwaters of the

San Marcos River The San Marcos River rises from the San Marcos Springs, the location of Aquarena Springs, in San Marcos, Texas. The springs are home to several threatened or endangered species, including the Texas blind salamander, fountain darter, and Texas wi ...

. They appeared to need clean and clear water, with little temperature variability. They apparently also preferred shallow, quiet water, along with partial shade.

Extinction

As of 1969, the population was less than 1,000 individuals. The species was threatened by reduced spring flows and pollution, including sprayed herbicide along the river and introduced fish ('' Gambusia affinis'') and plants (''

Colocasia esculenta Taro () (''Colocasia esculenta)'' is a root vegetable. It is the most widely cultivated species of several plants in the family Araceae that are used as vegetables for their corms, leaves, and petioles. Taro corms are a food staple in African ...

''). As no specimens have been sighted since 1983, the species is now considered extinct.

References

External links

San Marcos gambusia (''Gambusia georgei'')
page from the Texas Parks and Wildlife Department {{Taxonbar, from=Q2241526 Gambusia San Marcos, Texas Endemic fauna of Texas Extinct animals of the United States Fish described in 1969 Taxa named by Clark Hubbs Fish of North America becoming extinct since 1500 ESA endangered species Species made extinct by human activities