Water treader

Water treader
Water treaders
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Heteroptera
Infraorder: Gerromorpha
Superfamily: Mesovelioidea

(but see text)

Water treaders (superfamily Mesovelioidea) 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.[1]

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 abbreviations 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.


As noted above, the groups often treated as subfamilies make up the major clades 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.

  • 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


  1. ^ ToL (1995)