Species within the Etheostomatinae are all small fish, mostly less than 11 centimetres (4.3 in) in length, and their bodies are slightly compressed or fusiform in shape.
[2] Etheostomatinae, as a species rich and diverse sub-family within the family Percidae of freshwater ray-finned fishes, is composed of multiple genera including Ammocrypta, Crystalluria, Etheostoma, Nothonotus, and Percina, all of which have been observed as monophyletic groupings through molecular phylogenies.
[8] Speciation events are common across species of this subfamily, one example includes Barcheek darters, an ancient monophyletic grouping residing in the eastern highlands which under time-calibrated molecular phylogenetic analysis of the mitochondrial genome has presented five novel cryptic species previously thought to be associated with Etheostoma basilare.
It is more common between species with similar egg-laying behavioral mechanisms and within the same phylogenetic clade, with sperm viability being the limiting factor of hybridization.
Hybridization is predominantly found within species of large geographic ranges, larger populations, and egg-burying reproductive mechanisms.
[10] Darters are composed of fusiform shaped bodies that are typically less than 11 centimeters in length, and characteristically host a reduced or lack an air bladder, allowing them to reside in benthic regions of lakes, streams, and rivers.
[11] Another prominent feature held by females across darter lineage is the presence of gential papillae, fleshy protuberances between the anus and anal fin and are associated with egg laying abilities.
Phylogenetic analyses expressed that the common ancestor of Etheostomatinae buried eggs with the help of tube-like appendage with a genital pore, a pore that releases the females eggs, held at the dorsal-posterior end known as tube papillae, leading researchers to believe this is the ancestral state of darters.
[14] Observations have been made that the majority of species across the diverse genus Etheostoma and that they attach eggs to their surroundings for protection.
Male darters have been found to hold female preferences and mate choice and aggression correlated to their coloration differences expressing biases regarding intra and intersexual selection.
The influence of life-history strategy on genetic differentiation and lineage divergence in darters (Percidae: Etheostomatinae).
Preference for conspecific mates in sympatric and allopatric darters (genus Etheostoma): comparative evidence for geographical and sex effects.
Temporal patterns of diversification and microendemism in Eastern Highland endemic barcheek darters (Percidae: Etheostomatinae).
Ecological and morphological variation of darters among assemblages in Oklahoma streams (Doctoral dissertation, Kansas State University).
Male behaviour predicts trait divergence and the evolution of reproductive isolation in darters (Percidae: Etheostoma).
Life history tactics of darters (Percidae: Etheostomatiini) and their relationship with body size, reproductive behaviour, latitude and rarity.
Investigating Differences in the Gene Expression Profiles of Rainbow Darter (Percidae: Etheostoma caeruleum) Populations Across Space and Time (Doctoral dissertation, Southeastern Louisiana University).