Lepomis

''Lepomis'' or true sunfish is a genus of North American freshwater fish from the family Centrarchidae in the order Centrarchiformes. The generic name ''Lepomis'' derives from the Greek ("scale") and ("cover", "plug", " operculum"). The genus' most recognizable species is perhaps the bluegill.

Some ''Lepomis'' species can grow to a maximum overall length of , though most average around . Many species are sought by anglers as popular panfishes, and large numbers are bred and stocked in lakes, rivers, ponds and wetlands. They are widely distributed throughout the freshwater lakes and river tributaries of the United States and Canada, and several species have been translocated and flourished around the world, even becoming pests. Aquarium trade in some ''Lepomis'' species is prohibited in Germany for this reason.

''Lepomis'' species, among others, are sometimes referred to as bream, but the term is also used to refer explicitly to the unrelated European cypriniform fish of genus ''Abramis''.

Phylogeny

Phylogeny of all ''Lepomis'' species based on a partitioned mixed-model Bayesian analysis of a seven gene dataset of mitochondrial and nuclear gene DNA sequences by Near et al. (2005), expanded with fossil species. Subgenera in bold follow Bailey (1938):

^*) ''L. peltastes'' was not originally included in the analysis by Near et al. (2005) and is included here based on commonly accepted sister relationship to ''L. megalotis''.

^**) See section 'Evolutionary History' below for explanation.

^***) Phylogenetic position in clade II uncertain. See section 'Fossil record' for clarification.

Evolutionary history

Phylogenetic reconstructions using a combination of nuclear and mitochondrial DNA sequences calibrated with fossils to estimate ages of divergences suggests that the genus ''Lepomis'' diverged from the black bass in genus ''Micropterus'', its sister taxon, about 25 million years ago. The deepest split among currently living species of ''Lepomis'' is dated to ~15 million years ago and separates genus ''Lepomis'' into two clades: clade I that leads to the modern bluegill, orange-spotted, green, and warmouth sunfish, and a clade II that includes the modern long-ear, red-breasted, pumpkinseed, redear, and red-spotted sunfish (see section 'Phylogeny' above). The timing of this speciation event roughly corresponds with the Middle Miocene disruption that resulted in increased aridity on the plains of North America and a transition from savannah to grasslands, although the relevance of these environmental changes to the evolution of ''Lepomis'' is unclear.

Fossil record

No fossils unambiguously assigned to genus ''Lepomis'' are currently known from the putative stem-lineage that must have existed between 25 and 15 million years ago, spanning most of the early Miocene.

Currently, four extinct species of ''Lepomis'' are known from the fossil record:

There are at least two as yet undescribed fossil species of ''Lepomis'' that reach back to the middle Miocene:
* †''Lepomis'' sp. A consists of fragmentary fossils of its lower jaw from the Valentine Formation of Nebraska, dated to 13.5 million years ago, and shows morphological similarities to the modern ''Lepomis microlophus'', although its great age means that this species predates the divergence of any of the living species.
* †''Lepomis'' sp. B was found in deposits from the Ogallala Formation of Kansas, dated to 12 million years ago.

Two other more recent fossil species appear to be closely allied to ''Lepomis gulosus'', and indeed their earliest occurrence may be close to the divergence of the lineage leading to the modern warmouth from other species of ''Lepomis'':
* †'' Lepomis kansasensis'' lived 6.6 million years ago in the Ogallala Formation of Kansas, and had pterygoid teeth, indicating a close relationship to the warmouth.
* †'' Lepomis serratus'' is known from 3.4 to 2.0 million year old deposits in the Keim Formation of Nebraska, and also appears to be closely related to or ancestral to the warmouth on the basis of its preopercle.

Species

There are currently 13 recognized species in this genus:

''Lepomis'' frequently hybridize and many different hybrid combinations have been observed in the wild. Some of these hybrids include:
* ''Lepomis macrochirus'' × ''cyanellus'' (greengill sunfish)
* ''Lepomis macrochirus x microlophus'' (gillcracker)
*''Lepomis cyanellus x gibbosus'' (pumpgreen sunfish)
*''Lepomis cyanellus x gulosus'' (green sunfish x warmouth)
*''Lepomis gulosus x macrochirus'' (warmouth x bluegill)
*''Lepomis macrochirus x megalotis'' (bluegill x longear sunfish)
* ''Lepomis gibbosus x macrochirus'' (pumpkingill)
*''Lepomis auritus x cyanellus'' (redbreast x green sunfish)
*''Lepomis microlophus x cyanellus'' (redear x green sunfish)
*''Lepomis auritus x microlophus'' (redbreast x redear sunfish)
*''Lepomis macrochirus x punctatus'' (bluegill x spotted sunfish)
*''Lepomis gibbosus x peltastes'' (pumpkinseed x northern sunfish)
*''Lepomis megalotis x cyanellus'' (longear x green sunfish)
*''Lepomis miniatus x punctatus'' (redspotted x spotted sunfish)

References

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Lepominae
Taxa named by Constantine Samuel Rafinesque
Extant Miocene first appearances