Species Description: The body is entirely scaled, and body coloration on the eyed side is usually olive to brown, with variable dark blotches and spots and diffuse lines. Conspicuous tufts of hairlike cirri are usually scattered on the body surface. Pectoral fins are present (Hoese and Moore 1977, Robbins et al. 1986).
Ray counts are variable, with 52-58 dorsal soft rays, and 39-44 anal soft rays (Froese and Pauly (2008). Ray count ranges presented in Hoese and Moore (1977) differ slightly, with 50-58 dorsal soft rays, and 38-48 anal soft rays.The pectoral fin on the eyed side possesses 5-6 soft rays (Hoese and Moore 1977).
Potentially Misidentified Species: Careful examination allows Achirus lineatus and other right-eyed achirids to be distinguished from all co-ocurring flatfish of the families Bothidae (lefteye flounders) and Cynoglossidae (tonguefishes), all of which have the left side up. The right-eyed flounders of family Pleuronectidae typically inhabit colder waters than A. lineatus (Robbins et al. 1986).
Within the Achiridae, the absence of vertical body bars should be sufficient to distinguish A. lineatus from three co-occurring species, the North American naked sole (Gymnachirus melas), Gulf of Mexico fringed sole (G. texae), and hogchoker (Trinectes maculatus). Lined sole are also easily differentiated from scrawled sole (Trinectes inscriptus), whose side-up body is covered by a network of irregular dark lines (Robbins et al. 1986).
Regional Occurrence: Achirus lineatus is a western Atlantic species, occurring in Florida and in the northern Gulf of Mexico southward to northern Argentina (Froese and Pauly 2008).
IRL Distribution: Lined sole may be encountered throughout the subtidal benthic Indian River Lagoon environment.
Age, Size, Lifespan: Froese and Pauly (2008) note a maximal total length of 23 cm.
Abundance: Seasonal field sampling in coastal and inshore Louisiana waters by Gunter (1938) revealed Achirus lineatus to not be among the more common species. Peak abundance occurred in the fall, from September through November. More recent collections from Florida Bay and Louisiana also indicate A. lineatus is typically not a numerically dominant estuarine ichthyofaunal component (Peterson and Turner 1994, Matheson et al. 1999).
In contrast, Machado et al. (2002) indicate A. lineatus was ranked 23rd of the 39 most abundant demersal fish species collected from Sepetiba Bay, Brazil from 1993-1996, occurring in 43.5 of trawl samples taken. Stoner (1986) also reports A. lineatus as the dominant fish species in the estuary of Laguna Joyuda, Puerto Rico, accounting for greater than half the collection totals at some sampling stations.
Reproduction: Reproduction appears to occur year-round, at least in some portions of the animal's distributional range. Stoner (1986) found small juveniles (<26 mm SL) in all months except October in Laguna Joyuda, Puerto Rico. Published information regarding other reproductive aspects in this species is sparse.
Embryology: Keith et al. (2000) indicate a brief planktonic larval duration for the species. Migration of the left eye to a position adjacent to the right eye on the new top side of the animal occurs during this period (Robbins et al. 1986).
Temperature: The restricted subtropical to tropical distribution of A. lineatus suggests a somewhat narrow thermal tolerance for the species. Froese and Pauly (2008) indicate 30°N as the northern distribution limit.
Salinity: Achirus lineatus is a broadly euryhaline species, i.e., having a wide salinity tolerance. Individuals have been collected in near-freshwater from the upper portions of the St. Lucie and Caloosahatchee estuaries, Florida (Gunter and Hall 1963), and aquarium hobbyists sometimes refer to A. lineatus as a freshwater sole. At the other end of the salinity spectrum, Cervigon et al. (1992) note the presence of A. lineatus in hypersaline lagoons.
Although Ronnins et al. (1986) note individuals rarely occur in coastal waters of less than 15 ppt, Stoner (1986) indicates A. lineatus is a year-round resident of seasonal wet/dry-influenced Laguna Joyuda, Puerto Rico, where salinity is estimated to range between 4 ppt and 44 ppt.
Trophic Mode: Achirus lineatus is a benthic predator that feeds primarily on worms, crustaceans, and small fish.
Competitors: Lined sole are likely to compete for suitable benthic prey with co-occurring flatfishes and other bottom-feeding fish species.
Parasites: The nematode Procamallanus (=Spirocamallanus) pereirai has been reported as a parasite of Tampa Bay Achirus lineatus (Hutton 1964).
Achirus lineatus inhabits reefs, coastal and estuarine seagrasses, and sand and mud bank habitats to a depth of 20 m. It is a cryptic species, capable of blending in with occupied sand and mud habitats, and often buries itself in the sand with only its eyes exposed (Kritzler 1951, Tolan et al. 1997, Matheson et al. 1999, Froese and Pauly 2008).
Activity Time: Lined sole are typically active in the evening, spending most daylight hours buried in shallow sand.
Special Status: None.
Economic Importance: Though related to commercially important soles, Achirus lineatus itself is of relatively little market value.
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