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Pleuronectiformes: Achiridae 1925

ACHIRIDAE American soles by T.A. Munroe, National Marine Fisheries Service, National Museum of Natural History, Washington, D.C., USA iagnostic characters: Small flatfishes (usually smaller than 35 cm) with eyes and colour pattern on Dthe right side (left-eyed individuals very rare); body round or oval in outline and strongly com- pressed. Snout rounded, mouth small, oblique and asymmetrical, subterminal; lips fleshy, often fringed with dermal flaps or fleshy convolutions; teeth minute, villiform, difficult to see, better developed on blind-side jaws, occasionally absent; without externally prominent bony orbits, eyes small to minute. Preopercular margin not free, concealed by skin or represented only by a naked superficial groove. Fins without spines, all rays soft; dorsal fin extending forward well in advance of eyes, the anterior rays concealed within a fleshy dermal envelope and difficult to see. Dorsal and anal fins not confluent with caudal fin. Pectoral fins present or absent, if present that of right side usually longer than left (left pectoral fin usually vesti- gial or absent on blind side); pelvic fins present bilaterally (apparently fused externally in Soleonasus), either free or joined to anal fin.Lateral line essentially straight, often indistinct, but most readily seen on ocular side, usually crossed at right angles by accessory branches (achirine lines) extending toward dorsal and anal fins; lateral line often ornamented with minute fleshy flaps or cirriform dermal processes. Scales ctenoid (rough to touch) or absent (Gymnachirus).Colour: ocular side brownish to near black, plain, blotched, scrawled, or with dark crossbars; blind side predominantly pale but often shaded or blotched with irregular brown patches or spots; albinistic or ambicolourate (replication of ocular side pigment on blind side) speci- mens rare.

eyes on right side

no free preopercular margin

Habitat, biology, and fisheries: Inhabit marine, estuarine, or fluviatile (Soleonasus, Pnictes, some species of Achirus and Trinectes) waters, hypersaline environments, and occur in depths to about 300 m. Moderately small fishes (to about 35 cm, but most usually less than 25 cm), edible, but of no commercial value in Area 31. Most species live close to shore and occur on a variety of soft sandy or muddy sediments. The majority of spe- cies feed on benthic invertebrates, with occasional small fishes included in diets of larger species. Along with other small flatfishes, achirid soles constitute a minor proportion of industrial fish catches in some areas. Al- though edible, these relatively small-sized species are usually not harvested for consumption, except in artisanal fisheries where they are sometimes marketed fresh (especially larger individuals). Because of their small size, these species frequently are taken in the shrimp trawl fishery, where they are considered a nui- sance because they clog nets and thereby reduce efficiency of fishing gear. 1926 Bony Fishes

Similar families occurring in the area preopercular Bothidae and Scophthalmidae: eyes on left side; margin free preopercular margin free. Cynoglossidae: eyes on left side; dorsal and anal fins confluent with caudal fin, preopercular margin hidden. Poecilopsettidae: eyes on right side, however, margin of preopercle free and not concealed by skin and/or scales.

eyes on left side dorsal and anal fins confluent with caudal fin Bothidae

preopercular Cynoglossidae margin free and Poecilopsettidae not concealed Key to the species of Achiridae occurring in the area Note: Nodogymnus herein regarded as a junior synonym of Gymnachirus. 1a. Head, body and fins lacking scales, and covered with very loose skin; ocular side of adults usually with prominent dark, relatively wide, crossbands ...... (Gymnachirus) ® 2 1b. Body covered with scales, skin not very loose; ocular side of adults without prominent crossbands (crossbands if present, faint and narrow) ...... ® 4

2a. Long (to 6.0 mm) dermal cirri on interspaces or on crossband-interspace margins dorsal to right lateral line, usually persisting in adults; 5 to 9 (usually less than 8) accessory sensory lines crossing right lateral line between pectoral-fin base and caudal-fin base; 25 to 49 (usually more than 30) narrow primary crossbands plus partial crossbands originating or terminating at dorsal margin on ocular side from tip of snout to caudal extremity (in speci- mens with complete peripheral stripe, count modified to include those stripes reaching or approximating marginal band); west Florida to Yucatán Peninsula ...... Gymnachirus texae 2b. Dermal cirri on right side relatively short ( less than 2.0 mm) or absent in adults (sometimes with moderately long, 2 to 3 mm, cirri in juveniles); 7 to 10 (usually more than 7) accessory sensory lines crossing right lateral line between pectoral-fin base and caudal-fin base; 13 to 32 (usually 30 or fewer) narrow primary and secondary crossbands plus partial crossbands originating or terminating at dorsal margin on ocular side from tip of snout to caudal extremity (in specimens with complete peripheral stripe, count modified to include those stripes reaching or approximating marginal band) ...... ® 3

3a. Thirteen to 21 (usually 15 to 18) narrow primary crossbands plus partial crossbands origi- nating or terminating at dorsal margin on ocular side from tip of snout to caudal extremity (in specimens with complete peripheral stripe, count modified to include those stripes reaching or approximating marginal band) of adults; young exhibiting various degrees of melanism on both sides; Yucatán to Brazil ...... Gymnachirus nudus 3b. Fifteen to 32 (usually 20 to 30) narrow primary crossbands plus partial crossbands origi- nating or terminating at dorsal margin on ocular side from tip of snout to caudal extremity (in specimens with complete peripheral stripe, count modified to include those stripes reaching or approximating marginal band) in adults; young exhibiting various degrees of melanism on both sides; Massachusetts to eastern Gulf of Mexico ...... Gymnachirus melas Pleuronectiformes: Achiridae 1927

4a. Left and right-side gill openings wide, confluent in front of pelvic fins ...... ® 5 4b. Gill openings reduced to narrow slits, separate, not confluent anteriad ...... ® 11

5a. Interbranchial septum entire, without foramen; ocular-side pectoral fin ru- dimentary, normally with a single ray (rarely with 2 or 3 fin rays) or absent altogether; blind-side pectoral fin usually absent (or rarely present, with a single ray) ...... (Trinectes) ® 6 foramen in 5b. Interbranchial septum pierced by a interbranchial foramen (Fig. 1); ocular-side pecto- septum ral fin usually with 2 to 8 rays; blind-side pectoral fin either with a ® Fig. 1 lateral view of head with gill cover folded single ray or absent ...... (Achirus) 9 forward (Achirus)

6a. Ocular surface with wavy pattern of dense dark brown reticulations on a light yellowish brown background; body pigmentation terminating abruptly at base of caudal fin; caudal fin uniformly light yellow to nearly transparent, without streaking on fin rays and membranes; small pectoral fin on ocular side ...... Trinectes inscriptus 6b. Ocular side grey-green to brown without reticulated pattern (some specimens with darker spots or with 7 or 8 wavy transverse crossbands); caudal fin with similar pigmentation to that on body, and with dark streaking throughout length of fin ...... ® 7

7a. Eyes relatively small, eye diameter 2.5 to 3.0 in snout length ...... Trinectes microphthalmus 7b. Eyes larger, eye diameter 1.8 to 2.5 in snout length ...... ® 8

8a. Dorsal-fin rays 54 to 60; anal-fin rays 40 to 45; ocular-side pectoral fin usually with a single ray ...... Trinectes paulistanus 8b. Dorsal-fin rays 50 to 56; anal-fin rays 36 to 42; ocular-side pectoral fin usually absent (only rarely with a single ray)...... Trinectes maculatus

9a. Dorsal-fin rays 59 to 68; anal-fin rays 43 to 51; ocular-side pectoral fin usually with 3 or 4 rays ...... Achirus achirus 9b. Dorsal-fin rays 49 to 60; anal-fin rays 38 to 48; ocular-side pectoral fin usually with 5 or 6 rays ...... ® 10

10a. Caudal fin with numerous dark spots or irregular blotches; blind side of body in caudal re- gion darkly shaded ...... Achirus lineatus 10b. Caudal fin lacking dark spots or blotches; blind side of body in caudal region not promi- nently shaded ...... Achirus declivis

11a. Dorsal and anal fins connected by membrane to caudal fin; eyes minute, barely visible, di- ameter much less than interorbital width; ocular-side pelvic fin rudimentary, or absent; blind-side pelvic fin distinct from that of ocular-side ...... Apionichthys dumerili 11b. Dorsal and anal fins free from caudal fin; eyes somewhat larger, diameter greater than interorbital width; pelvic fins present and appearing fused externally, that is, contained within single dermal envelope (visible only with transmitted light or by dissection) . . Soleonasus finis 1928 Bony Fishes

List of species occurring in the area The symbol 0 is given when species accounts are included. 0 Achirus achirus (Linnaeus, 1758). Achirus declivis Chabanaud, 1940. To 18 cm TL. Belize to Santa Catarina, Brazil; Trinidad, Jamaica, St. Barthelemy, and Suriname. 0 Achirus lineatus (Linnaeus, 1758). 0 Apionichthys dumerili Kaup, 1858. 0 Gymnachirus melas Nichols, 1916. 0 Gymnachirus nudus Kaup, 1858. 0 Gymnachirus texae (Gunter, 1936). Soleonasus finis Eigenmann, 1912. To 10 cm SL. Fresh water, Guyana. 0 Trinectes inscriptus (Gosse, 1851). 0 Trinectes maculatus (Bloch and Schneider, 1801). Trinectes microphthalmus (Chabanaud, 1928). To 9 cm TL. Trinidad and Tobago to SE Brazil. 0 Trinectes paulistanus (Miránda-Ribeiro, 1915).

References Cervigón, F. and nine co-authors. 1993. FAO species identification sheets for fishery purposes. Field guide to the commercial marine and brackish-water resources of the northern coast of South America. Rome, FAO, 513 p. Dawson, C.E. 1964. A revision of the western Atlantic flatfish genus Gymnachirus (the naked soles). Copeia, 1964(4):646-665. Figueiredo, J.L. and N.A. Menezes. 2000. Manual de peixes marinhos do sudeste do Brasil. VI. Teleostei (5). Museu de Zoologia Universidade de São Paulo, São Paulo, 116 p. Keith, P., P.-Y. Le Bail, and P. Planquette. 2000. Atlas des poissons d’eau douce de Guyane. Tome 2, fascicule I. Batrachoidiformes, Mugiliformes, Beloniformes, Cyprinodontiformes, Synbranchiformes, Perciformes, Pleuronectiformes, Tetraodontiformes. Patrimoines naturels (MNHN/SPN), 43(1):286 p. Topp, R.W. and F.H. Hoff, Jr. 1972. Flatfishes (Pleuronectiformes). Mem. Hourglass Cruises, Fla. Dep. Nat. Resour., St. Petersburg, Florida, 4(2):1-135. Pleuronectiformes: Achiridae 1929

Achirus achirus (Linnaeus, 1758) HIK En - Drab sole; Fr - Sole sombre; Sp - Suela lucia. Maximum size 37 cm, commonly to 30 cm. Occurs on sand-mud bottoms in estuarine waters to almost fresh water at depths of 20 m or less. Growth rate relatively slow. Spawns between July and September. Feeds on small invertebrates (especially crustaceans) and small fishes. Often found completely covered with sediment, presumably for protection from predators and to ambush prey.Artisanal fishery only.At present, this species is under-exploited; it might become an important fishery resource in estuarine areas of the region. Highly es- teemed foodfish in the Guyanas. From the Gulf of Paria to the mouth of the Amazon river.

Achirus lineatus (Linnaeus, 1758) ULI En - Lined sole; Fr - Sole achire; Sp - Suela pintada. Maximum size 23 cm, commonly to 17 cm. Occurs in brackish waters on sand-mud bottoms and hypersaline lagoons. In Barataria Bay, LA, individuals were taken at salinities ranging from 2.0 to 27.0 ‰. Grows relatively fast. Seasonally, these fishes occurred in the upper bay during the summer and autumn and in the lower bay during the winter and spring. Spawning has been reported in the eastern Gulf of Mexico from April to Novem- ber when daylight is greater than 12 hours and water temperature is greater than 20°C.Feeds on benthic inver- tebrates (especially crustaceans) and small fishes. Artisanal fishery only. Caught with beach nets. Of negligible commercial importance because of its small average size. South Carolina to northern Argentina. 1930 Bony Fishes

Apionichthys dumerili Kaup, 1858 IYD En - Longtail sole; Fr - Sole queue longue; Sp - Suela colalarga. Maximum size 15 cm, commonly to 11 cm. Taken as bycatch in trawl fisheries for shrimps. Of negligible com- mercial importance because of its small average size. From the Gulf of Paria to the mouth of the Amazon river. Estuarine areas of rivers Orinoco, Corantjin, Oiapoque, Amazonas, and Grajaú and in marine areas under the influence of these rivers.

Gymnachirus melas Nichols, 1916 GHM En - Naked sole. Maximum size to 17 cm standard length.Occurs at depths of 2 to 185 m.In the Gulf of Mexico, individuals were collected in areas with bottom temperatures of 19 to 29°C and bottom salinities of 35.14 to 36.45 ‰. Based on stomach contents of a small sample of individuals from the Gulf of Mexico, these fish prey upon poriferans, bi- valves, onuphiod polychaetes, ostracods, amphipods, cumaceans, brachyurans, stomatopods, and lancelets; small crustaceans were dominant. Spawning occurs from May to November. Length at maturity is around 8 to 10 cm standard length. Most individuals mature during February, March, and April; smallest specimens occur in June and July. Fecundity of a 116 mm specimen was estimated at 15 500 eggs; egg diameter ranged from 0.2 to 0.9 mm. East coast of the USA (Martha’s Vineyard, Massachusetts, to Dry Tortugas), eastern Gulf of Mexico; Bahamas. Pleuronectiformes: Achiridae 1931

Gymnachirus nudus Kaup, 1858 En - Nude sole; Fr - Sole nue; Sp - Suela desnuda. Maximum size 15 cm, commonly to 12 cm. Occurs in relatively shallow marine waters, over soft bottoms to ap- proximately 100 m. A moderately rare species. Taken as bycatch in industrial trawl fisheries for shrimps and finfishes. Of little commercial importance. Campeche, Mexico, to Rio Grande do Sul, Brazil; Greater Antilles, Virgin Islands, and Jamaica.

Gymnachirus texae (Gunter 1936) En - Fringed sole. Maximum size to 12 cm standard length. Occurs over mud bottoms at depths of 20 to 187 m, but taken most frequently at 55 to 90 m. North central and western Gulf of Mexico to Campeche Bank and Yucatán coast. 1932 Bony Fishes

Trinectes inscriptus (Gosse, 1851) En - Scrawled sole; Fr - Sole réticulée; Sp - Suela reticulada. Maximum size 15 cm, commonly to 10 cm. Occurs on soft bottoms, in clear waters of oceanic islands and in bays and mangrove-lined lagoons along continental coasts. Caught with experimental beach nets. Of negligi- ble commercial importance because of small average size. South Florida and Bahamas to Venezuela; absent from the Gulf of Mexico; rare in the Guyanas.

Trinectes maculatus (Bloch and Schneider, 1801) TMT En - Hogchoker. Maximum size to 20 cm. Typically occurs in habitats with low water clarity, moderate oxygen concentration, and mud bottoms in shallow (50 to 60 m), inshore waters. Also ascends coastal rivers and enters fresh water. Spawning occurs May through October in inshore waters and estuaries. Eggs contain large numbers of oil globules and are positively buoyant. Following hatching, larvae move upstream and congregate in a low salin- ity nursery area on shallow mud flats close to the salt-fresh water interface where they remain during winter.As spring approaches juveniles move toward the spawning area. These 2 distinct movements, upstream toward the nursery area in autumn and downstream toward the spawning area in spring, apparently continue at least through the fourth year.As the fish mature they progressively increase their range of travel away from the nurs- ery ground toward higher salinities. Juvenile salinity intolerance is not the driving mechanism of this migration pattern.Females grow larger and older than males;majority of individuals of both sexes mature as early as age 2 (greater than or equal to 70 mm total length); may reach 7 yrs of age. Feed on a variety of worms and crusta- ceans. Of no commercial or recreational importance; considered a trash fish. Collected incidentally in seines and bottom trawls. East coast of USA (Massachusetts to Florida), throughout Gulf of Mexico, to Panama. Pleuronectiformes: Achiridae 1933

Trinectes paulistanus (Miránda-Ribeiro, 1915) En - Slipper sole; Fr - Sole pantoufle; Sp - Suela chancieta. Maximum size 18 cm, commonly to 12 cm. Occurs over soft bottoms in estuaries and hypersaline lagoons. Artisanal fishery only. Not very abundant. Caught with beach nets and taken as bycatch in the industrial trawl fishery for shrimps. Usually not marketed. Colombia, Suriname, to Santa Catarina, Brazil.

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