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Taxon profile

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genus

Alphestes Bloch & Schneider, 1801

kingdom Animalia - animals »  phylum Chordata - chordates »  class Actinopterygii - ray-finned fishes »  order Perciformes - perch-likes »  family Serranidae - sea basses and groupers

Description

Small compressed groupers with large eyes, short snout, and coloration that resembles their benthic habitat. Body depth less than head length and contained 2.3 to 3.1 times in standard length, the body width contained 1.9 to 2.6 times in the depth. Head length contained 2.4 to 2.6 times in standard length, the dorsal head profile nearly straight; snout length less than or subequal to orbit diameter; preorbital narrow, its depth contained 18 to 26 times in head length; preopercle subangular, the posterior edge distinctly serrate, with a large spine (usually hidden by skin) directed downward and forward at the “angle”; rear nostrils round or oval, not much larger than front ones; ventral edge of maxilla smoothly curved (no step or bony knob at posterior end); supramaxilla well developed; a pair of small canines (hidden by lips) at front of both jaws; 3 to 5 rows of small slender teeth at side of lower jaw and similar but smaller teeth on vomer and palatines. Dorsal fin with XI spines and 17 to 19 soft rays, the fin origin over opercle and in front of vertical at upper end of pectoral-fin base, the membranes incised between the spines; anal fin with III spines and 9 rays; caudal fin rounded, with 8 branched rays and 7 procurrent rays in upper part and 7 branched rays and 7 procurrent rays in lower part. Midlateral-body scales smooth. Supraneural bones 2, the posterior one approximately straight, about three-fourths length of first one and situated just anterior to tip of second neural spine; no trisegmental pterygiophores; rear edge of first dorsal-fin pterygiophore not excavated for tip of third neural spine; epipleural ribs on vertebrae 1 to 9; skull with well-developed cranial crests, the frontoparietal crests parallel; no transverse wall on supraethmoid, which forms floor of pit between end of frontals; medial process of epiotics produced, much longer than lateral process; interorbital width less than vomer width.

Ecology

The mutton hamlets are shallow-water, crypticly coloured, secretive fishes that are easily overlooked in their typical seagrass habitat. They are sedentary during the day, hiding in crevices or lying among seaweed, and rely on their effective camouflage to escape detection. Sometimes they will even lie on their side and partly cover themselves with sand. With their cryptic coloration and sedentary habitats, they resemble scorpaenid fishes and can easily be approached or even touched. Mutton hamlets are nocturnal predators feeding mainly on benthic crustaceans.

Distribution

The genus Alphestes is represented in the eastern Pacific and western Atlantic oceans.

Taxonomy

Alphestes was regarded as a subgenus of Epinephelus by C.L. Smith (1971), who wrote, “Although the dorsolateral (skull) crests are parallel to each other they are more similar to those of Epinephelus than to those of Mycteroperca and the general aspect of the skull is clearly that of other species of Epinephelus. The postocular skull process bears the same relationship to the crest that it does in Epinephelus and is unlike that of Mycteroperca.” Heemstra and Randall (1993) agree that the cranium of Alphestes afer is more similar to the crania of western Atlantic species of Epinephelus than it is to any Mycteroperca species, but this does not mean that Alphestes and Epinephelus are necessarily congeneric. Smith (1971) gave no diagnosis for his (expanded) genus Epinephelus, nor did he mention any characters that might indicate its monophyletic status. The large antrorse spine at the corner of the preopercle in Alphestes species does not occur on any species of Epinephelus. The only other grouper with a single large antrorse spine at the corner of the preopercle is Gonioplectrus hispanus; and it differs markedly from Alphestes in dorsal- and anal-fin counts, development of opercular spines, maxilla shape, head shape, body shape, and cranial configuration. Although Alphestes may be more closely related to Epinephelus than to any other genus, Heemstra and Randall (1993) believe that the distinctive antrorse preopercle spine, head configuration (very short snout and narrow preorbital), and smooth scales justify recognition of a separate genus for these three species. Johnson and Keener (1984) described a distinctive feature of the late postlarvae (15 mm) and small juveniles (38 to 60 mm) of Alphestes: the dorsal and lateral surfaces of the neurocranium from mid orbit to the nape are extremely rugose. This condition was not seen in other grouper larvae that they examined and is further justification for the recognition of Alphestes as a valid genus. Heemstra and Randall (1993) point out that the sedentary behaviour of Alphestes (see above) is also unlike any other grouper known to them.

Sources

Food and Agriculture Organization of the United Nations, 1993, Heemstra, P.C.; Randall, J.E., FAO species catalogue. Vol. 16. Groupers of the world (Family Serranidae, Subfamily Epinephelinae). An annotated and illustrated catalogue of the grouper, rock cod, hind, coral grouper and lyretail species known to date.
Author: Petr Čech

Included taxa

Number of records: 3

species Alphestes afer (Bloch, 1793) - Cherna
species Alphestes immaculatus Breder, 1936 - Pacific Mutton Hamlet
species Alphestes multiguttatus (Günther, 1867) - Rivulated Mutton Hamlet

Links and literature

CZ AQUATAB. World Wide Web electronic publication [genus/160]

Plíštil J. (Ed.) (2009): AQUATAB. World Wide Web electronic publication [http://aquatab.net] [as Alphestes Bloch & Schneider, 1801]
Data retrieved on: 17 January 2010

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