Heteroceridae
Encyclopedia
The Heteroceridae, or variegated mud-loving beetles, are a widespread and relatively common family of beetle
s. They occur on every continent except for Antarctica.
Around two hundred and fifty species of heterocerids are known to occur worldwide. They are most diverse in tropical and sub-tropical regions. Currently, 87 species are known from the New World, including 34 from the United States.
Variegated mud-loving beetles are brownish, dorsoventrally depressed shoreline inhabitants. Superficially they resemble small scarab
s with the tibiae armed with rows of robust flattened spines. The beetles live in shallow tunnels that they dig in damp soil around fresh and brackish lakes, rivers and ponds. Heterocerids have been reported to live in intertidal sandflats, making them one of the few groups of coleopterans with marine representatives. The uniform way in which they live seems to have favored the conservation of a "phenotypical uniformity in external morphology". Consequently, it is often quite difficult to identify one of these beetles to species relying on external morphology alone. Therefore, male genitalia are most often relied upon to identify species. Although few studies have been conducted on their ecology, heterocerids have been shown to be an important prey group for passerine
birds and frogs (Schmidt et al., 2003; Turner, 1959), and they appear to play a significant role in seed dispersal and burial in sandy soils.
In the most recent revision of the family, Francisco Pacheco
(1964) split the heterocerids into 20 different genera, erecting 17 new generic names based almost entirely on the features of male genitalia. Most systematists
have found Pacheco’s system complex and impractical because the ratio of genera to species is high and females cannot be identified. Consequently, his generic circumscriptions have not been widely accepted.
(1823) described Heterocerus pallidus and Heterocerus pusillus, the first New World species in the family. By the time George H. Horn (1890) produced his key to the genus Heterocerus, there were eleven described North American species in two genera. Horn’s key relied heavily on general coloration and elytral pattern for species diagnosis. No other major taxonomic work concerning Heteroceridae was published until 1964, when Pacheco published his dissertation on the systematics, phylogeny and distribution of the family in the New World. Pacheco described 25 additional New World species. He produced worldwide (excluding Africa) identification keys based largely on characters of the male genitalia, leaving it impossible to identify females to species. Pacheco also split the heterocerids into 20 different genera, erecting 17 new generic names, once again relying heavily on characters of the male genitalia. Distribution maps are included in Pacheco’s work; however, in his introduction, Pacheco admits that his work did not include enough material to create particularly informative distributions for many New World heterocerids. The only other monograph on the family Heteroceridae was published by Reinhold Charpentier (1965), and this encompassed the species of the Ethiopian region. Charpentier’s work included two species level keys, one based on male genitalia, the other on external characteristics. Charpentier saw no justification in dividing the family into any new taxa and he retained all 35 Ethiopian species in the genus Heterocerus. He did note, however, the great difference between the male genitalia of various groups of species.
Little subsequent taxonomic work was conducted with the family until the late 1980s, when W. V. Miller began describing species from around the world (Miller 1988, 1992). Miller’s work included the descriptions of seven new species from North America. These additions brought the number of North American species to 34. A key to 21 northeastern species, produced by Miller, appeared in Downie and Arnett’s Beetles of Northeastern North America (1995). This key relies mostly on elytral color patterns for species identification. In his work, Miller chose to apply a taxonomic scheme in which the heterocerids are divided into only five genera worldwide. European authors, namely S. Skalický (Czech Republic) and A. Mascagni (Italy), have described numerous species in the last ten years.
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s. They occur on every continent except for Antarctica.
Around two hundred and fifty species of heterocerids are known to occur worldwide. They are most diverse in tropical and sub-tropical regions. Currently, 87 species are known from the New World, including 34 from the United States.
Variegated mud-loving beetles are brownish, dorsoventrally depressed shoreline inhabitants. Superficially they resemble small scarab
Scarabaeidae
The family Scarabaeidae as currently defined consists of over 30,000 species of beetles worldwide. The species in this large family are often called scarabs or scarab beetles. The classification of this family is fairly unstable, with numerous competing theories, and new proposals appearing quite...
s with the tibiae armed with rows of robust flattened spines. The beetles live in shallow tunnels that they dig in damp soil around fresh and brackish lakes, rivers and ponds. Heterocerids have been reported to live in intertidal sandflats, making them one of the few groups of coleopterans with marine representatives. The uniform way in which they live seems to have favored the conservation of a "phenotypical uniformity in external morphology". Consequently, it is often quite difficult to identify one of these beetles to species relying on external morphology alone. Therefore, male genitalia are most often relied upon to identify species. Although few studies have been conducted on their ecology, heterocerids have been shown to be an important prey group for passerine
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
birds and frogs (Schmidt et al., 2003; Turner, 1959), and they appear to play a significant role in seed dispersal and burial in sandy soils.
In the most recent revision of the family, Francisco Pacheco
Francisco Pacheco
Francisco Pacheco was a Spanish painter, best known as the teacher of Diego Velázquez and Alonso Cano, and for his textbook on painting that is an important source for the study of 17th-century practice in Spain...
(1964) split the heterocerids into 20 different genera, erecting 17 new generic names based almost entirely on the features of male genitalia. Most systematists
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
have found Pacheco’s system complex and impractical because the ratio of genera to species is high and females cannot be identified. Consequently, his generic circumscriptions have not been widely accepted.
Taxonomy
Thomas SayThomas Say
Thomas Say was an American naturalist, entomologist, malacologist, herpetologist and carcinologist. A taxonomist, he is often considered to be the father of descriptive entomology in the United States. He described more than 1,000 new species of beetles and over 400 species of insects of other...
(1823) described Heterocerus pallidus and Heterocerus pusillus, the first New World species in the family. By the time George H. Horn (1890) produced his key to the genus Heterocerus, there were eleven described North American species in two genera. Horn’s key relied heavily on general coloration and elytral pattern for species diagnosis. No other major taxonomic work concerning Heteroceridae was published until 1964, when Pacheco published his dissertation on the systematics, phylogeny and distribution of the family in the New World. Pacheco described 25 additional New World species. He produced worldwide (excluding Africa) identification keys based largely on characters of the male genitalia, leaving it impossible to identify females to species. Pacheco also split the heterocerids into 20 different genera, erecting 17 new generic names, once again relying heavily on characters of the male genitalia. Distribution maps are included in Pacheco’s work; however, in his introduction, Pacheco admits that his work did not include enough material to create particularly informative distributions for many New World heterocerids. The only other monograph on the family Heteroceridae was published by Reinhold Charpentier (1965), and this encompassed the species of the Ethiopian region. Charpentier’s work included two species level keys, one based on male genitalia, the other on external characteristics. Charpentier saw no justification in dividing the family into any new taxa and he retained all 35 Ethiopian species in the genus Heterocerus. He did note, however, the great difference between the male genitalia of various groups of species.
Little subsequent taxonomic work was conducted with the family until the late 1980s, when W. V. Miller began describing species from around the world (Miller 1988, 1992). Miller’s work included the descriptions of seven new species from North America. These additions brought the number of North American species to 34. A key to 21 northeastern species, produced by Miller, appeared in Downie and Arnett’s Beetles of Northeastern North America (1995). This key relies mostly on elytral color patterns for species identification. In his work, Miller chose to apply a taxonomic scheme in which the heterocerids are divided into only five genera worldwide. European authors, namely S. Skalický (Czech Republic) and A. Mascagni (Italy), have described numerous species in the last ten years.