Poecilia velifera, known as the Yucatán molly or giant sailfin molly, is a poeciliid fish native to the Yucatán Peninsula in Mexico. It is typically under 10 cm (3.9 in) in length, but may reach 15 cm (5.9 in), with males somewhat larger than females. It belongs to a group of mollies known as sailfins, named for the large males' sail-like dorsal fin, a feature that is especially pronounced in P. velifera. The species occurs in a range of habitats, from coastal lagoons, estuaries, and salt marshes to freshwater pools in the interior of the peninsula; it is particularly associated with mangrove swamps and sinkholes known as cenotes. Yucatán mollies are primarily herbivorous, but also consume small invertebrates, adjusting their diet to available resources. They are preyed upon by a variety of larger fish, birds, and crocodiles, and are host to a diverse parasite fauna. Much of their time is spent browsing for food and maintaining their bodies. Males are divided into size-based classes which differ in appearance and behavior: large males flare their dorsal fin when they spar with other males and when they perform courtship displays for females, whereas small males remain hidden among females and mate through quick thrusts. A few weeks after mating, females give birth to live young. P. velifera produces viable hybrids with other mollies, including the naturally occurring P. mexicana×P. velifera. Although classified as a vulnerable species owing to threats in its native range, the Yucatán molly has been introduced to various countries in South America, Africa, and Asia through both mosquito control efforts and the ornamental fish trade. Its striking coloration and enlarged fins made it a popular species in the fishkeeping hobby, where it has been selectively bred and hybridized to produce a variety of fancy mollies.
Taxonomy
Yucatán mollies were misidentified in the early twentieth century as Mollienesia latipinna, with records from Progreso, Yucatán, and Isla Mujeres in 1902, from La Vega in Yucatán (misattributed to Tamaulipas) in 1904, and from a ciénega wetland near Progreso in 1906. Three specimens from Progreso were imported to Germany for the ornamental fish trade; the aquarist Johann Paul Arnold gave them to the ichthyologist Charles Tate Regan, who described them as a new species, Mollienesia velifera, in 1914. The original material—two males and one female—was deposited in the British Museum.
In a major taxonomic revision of poeciliid fish in 1963, the genus Mollienesia was subsumed into Poecilia, after which the species has been known as Poecilia velifera. Within Poecilia, it is placed in the subgenus Mollienesia alongside similar fishes collectively known as mollies. Mollies are divided into two groups: shortfins and sailfins. P. velifera belongs to the sailfins, named after the males' sail-like dorsal fin; the specific epithet velifera means "sail carrier". The species is commonly known as the Yucatán molly or sailfin molly and, in its native range, as topote de aleta grande in Spanish. Before the advent of genetic studies, P. latipinna was suggested as the ancestor of P. velifera; their close resemblance to P. kykesis also gave rise to the suggestion that the three might represent a single, variable species. It has subsequently been shown that the sailfin mollies form a species complex, a group of distinct but closely related species. These fall into two sister lineages: one adapted to salt water, comprising P. velifera and its closest relative, P. latipinna, and another associated with fresh water, comprising P. kykesis and P. latipunctata. Compared with shortfin mollies, the sailfin species P. velifera, P. latipinna, and P. kykesis show more pronounced differences between males and females, with males displaying their enlarged dorsal fin during courtship and in competitive interactions. These traits likely evolved in the common ancestor of the sailfin mollies.
Description The most striking feature of Poecilia velifera is its dorsal fin. It bears 15 to 21 rays, more than the dorsal fins of other sailfin mollies, making it diagnostic of the species. This fin rises exceptionally high in males, surpassing that of any other molly. Its base is long, extending over much of the back, and its color is dark with numerous pale spots, including bluish-green markings edged in black; in males, a row of larger dark spots is often present near the outer edge. The anal fin contains 10 rays. The pectoral fins are about as long as the head, while the pelvic fins reach the front of the anal fin; in males, one pelvic ray is elongated and equals the length of the gonopodium (male reproductive appendage). The tail fin is normally rounded and nearly plain; the lower corner may be slightly extended, and the upper part may show spotting, while the lower part remains unmarked and edged in black.
As in most poeciliids, the body is elongated—though relatively deeper—and the head is wedge-shaped, with moderately sized eyes set widely apart. The overall body color is olive green. Along the back and sides run dark brown longitudinal stripes, with broader ones following the rows of scales and narrower ones between them. Between these stripes are rows of small, iridescent spots, typically two on each scale, producing a characteristic shimmering effect; these markings, more vivid in males, take on green and bluish tones against a warm, golden ground color. The underside and head often shift toward greenish to orange hues with a subtle metallic blue sheen, and some individuals show irregular dark blotching across the body. Near the front of the body are three or four dark vertical bars, mostly concealed by the pectoral fins. Adult males in the collection of the Autonomous University of Yucatán measure 7.2–9.3 cm in total length (including tail fin; TL) and 5.7–7.5 cm in standard length (excluding tail fin; SL), whereas females measure 4.5–7.2 cm TL. Specimens as long as 15 cm have also been recorded. Males are polymorphic with respect to size and color and may be broadly divided into three classes: ornamented large males, ornamented intermediate males, and cryptic intermediate males (so called because they hide among females). P. velifera can be distinguished from the closely related P. kykesis by its larger head, lower scale count, distinctive coloration, and, above all, the much larger dorsal fin of males.
Distribution and habitat
Range
… excerpt ends here. Continue reading the full article.
