Water treader
Encyclopedia
Water treaders are insects in the order
Hemiptera
(true bugs). These "typical" bugs (suborder Heteroptera
) are the most ancient living lineage of the semiaquatic bugs of the infraorder Gerromorpha
.
At the first glance, they appear like a normal assassin bug adapted
to the lifestyle of a water strider
or a similar gerromorph. And in fact, apart from some minor autapomorphies of the assassin bugs and Pachynomidae (which together make up the most ancient Cimicomorpha
) versus those of the Mesovelioidea, this is essentially what they are.
The type genus
Mesovelia is quite large by the standards of Gerromorpha, but the other genera are small or even monotypic
(though new species
are occasionally described). A taxonomically interesting species is the Aaa Water Treader (Cavaticovelia aaa) with its odd but entirely legitimate
specific name – "aaa" is the only word (as opposed to abbreviation
s and acronyms) consisting of a triply repeated letter "a" currently in active use by English speakers. It is of Hawaiian origin, pronounced "a-aah" and means "clinker
lava
".
In some treatments, the Madeoveliidae are included in the Mesoveliidae as a subfamily, making the water treaders monotypic
at family
rank. But this is unnecessary, since it is fairly certain that the group consists of two well-marked and apparently monophyletic lineages, each consisting of several genera
. There is thus no reason to consider them anything but two good families.
s in this superfamily. Since taxonomic rank
is not a fixed measure of distinctness but simply a convenient way to address the main subdivisions – ideally the main clades – of the next higher-ranked taxon, there is really no justification to treat the superfamily Mesovelioidea as containing a single family with two subfamilies.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Hemiptera
Hemiptera
Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
(true bugs). These "typical" bugs (suborder Heteroptera
Heteroptera
Heteroptera is a group of about 40,000 species of insects in the Hemiptera. Sometimes called "true bugs", that name more commonly refers to Hemiptera as a whole, and "typical bugs" might be used as a more unequivocal alternative since among the Hemiptera the heteropterans are most consistently and...
) are the most ancient living lineage of the semiaquatic bugs of the infraorder Gerromorpha
Gerromorpha
Gerromorpha is an infraorder of insects in the "true bug" order Hemiptera. These "typical" bugs are commonly called semiaquatic bugs or shore-inhabiting bugs...
.
At the first glance, they appear like a normal assassin bug adapted
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
to the lifestyle of a water strider
Water strider
Gerridae is a family of true bugs in the order Hemiptera, commonly known as water striders, water bugs, magic bugs, pond skaters, skaters, skimmers, water scooters, water skaters, water skeeters, water skimmers, water skippers, water spiders, or Jesus bugs...
or a similar gerromorph. And in fact, apart from some minor autapomorphies of the assassin bugs and Pachynomidae (which together make up the most ancient Cimicomorpha
Cimicomorpha
Cimicomorpha is an infraorder of insects containing bugs....
) versus those of the Mesovelioidea, this is essentially what they are.
The type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
Mesovelia is quite large by the standards of Gerromorpha, but the other genera are small or even monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
(though new species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are occasionally described). A taxonomically interesting species is the Aaa Water Treader (Cavaticovelia aaa) with its odd but entirely legitimate
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
specific name – "aaa" is the only word (as opposed to abbreviation
Abbreviation
An abbreviation is a shortened form of a word or phrase. Usually, but not always, it consists of a letter or group of letters taken from the word or phrase...
s and acronyms) consisting of a triply repeated letter "a" currently in active use by English speakers. It is of Hawaiian origin, pronounced "a-aah" and means "clinker
Clinker
Clinker may refer to:* Clinker , construction method for wooden boats* Clinker , waste from industrial processes* Clinker , a kilned then quenched cement product* Clinker brick, rough dark coloured bricks...
lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
".
In some treatments, the Madeoveliidae are included in the Mesoveliidae as a subfamily, making the water treaders monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
at family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
rank. But this is unnecessary, since it is fairly certain that the group consists of two well-marked and apparently monophyletic lineages, each consisting of several genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
. There is thus no reason to consider them anything but two good families.
Systematics
As noted above, the groups often treated as subfamilies make up the major cladeClade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
s in this superfamily. Since taxonomic rank
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
is not a fixed measure of distinctness but simply a convenient way to address the main subdivisions – ideally the main clades – of the next higher-ranked taxon, there is really no justification to treat the superfamily Mesovelioidea as containing a single family with two subfamilies.
- Madeoveliidae
- Madeovelia Poisson, 1959
- Mesoveloidea Hungerford, 1929
- Mesoveliidae
- Cavaticovelia
- Cryptovelia Andersen & Polhemus, 1980
- Darwinivelia Andersen & Polhemus, 1980
- Mesovelia Mulsant and Rey, 1852
- Mniovelia Andersen & Polhemus, 1980
- Phrynovelia Horváth, 1915
- Speovelia Esaki, 1929