Tetrigidae
Tetrigidae is an ancient family in the order Orthoptera, which also includes similar families such as crickets, grasshoppers, and their allies. Species within the Tetrigidae are variously called groundhoppers, pygmy grasshoppers, pygmy devils or (mostly historical) "grouse locusts". Diagnostic characteristics. Tetrigidae are typically less than 20 mm in length and are recognizable by a long pronotum. This pronotum extends over the length of the abdomen, sometimes to the tip of the wings, and ends in a point. In other Orthoptera, the pronotum is short and covers neither the abdomen nor the wings. Tetrigidae are generally cryptic in coloration. Some  species have enlarged pronota that mimic leaves, stones or twigs. Other characteristics pygmy grasshoppers exhibit in comparison to other Orthoptera families are lack of arolium between the clows, first thoracic sternite modified into collar-like structure called sternomentum, tarsal formula 2-2-3, scaly fore wings, and developed hind wings. General biology. In temperate regions, Tetrigidae are generally found along streams and ponds, where they feed on algae and diatoms. The North American species "Paratettix aztecus" and "Paratettix mexicanus", for example, depend on aquatic primary production for between 80% and 100% of their diet. Riparian species are capable of swimming  on the surface of the water, and readily leap into the water when alarmed Some species in the tribe Scelimenini are fully aquatic and capable of swimming underwater. The highest biodiversity of Tetrigidae is found in tropical forests. Some tropical species are arboreal and live among mosses and lichens in tree buttresses or in the canopy, while others live on the forest floor. Like other Orthoptera, Tetrigidae have a hemimetabolous development, in which eggs hatch into nymphs. Unlike other temperate Orthoptera, however, temperate Tetrigidae generally overwinter as adults. Some subfamilies within the Tetrigidae, such as the Batrachideinae, are sometimes elevated  to family rank besides the Tetrigidae. "Arulenus miae" is a pygmy grasshopper species from the tropical mountainous rainforests of the Philippines. The species was firstly discovered in Facebook post. Etymology. Origin of the name of the family is not completely clear as there are different sources on its etymology. The name may be derived from Latin "tetricus" or "taetricus", meaning harsh, sour, severe. The name may also originate from the earlier name 'Tettigidae', based on "Tettix" (synonym of "Tetrix"), which was preoccupied by Tettigidae (synonym of Cicadidae). Because of the preoccupation by the cicadas' family name, the second 't' in  'tt' was changed into 'r', resulting in the word Tetrigidae. Subfamilies and Genera. Approximately 2,000 species have been described; according to the "Orthoptera Species File" the following genera are included: Subfamily Batrachideinae. Auth.: Bolívar, 1887; selected genera: Subfamily Cladonotinae. Auth.: Bolívar, 1887; selected genera: Subfamily Lophotettiginae. Auth.: Hancock, 1909 Subfamily Metrodorinae. Auth.: Bolívar, 1887; selected genera: Tribe Amorphopini Günther, 1939 Tribe Cleostratini Hancock, 1907 Tribe Clinophaestini Storozhenko, 2013 Tribe Miriatrini Cadena-Castañeda & Cardona, 2015 (monotypic) Tribe Ophiotettigini Tumbrinck & Skejo, 2017 Tribe Unassigned Subfamily Scelimeninae. Auth.: Hancock, 1907 Tribe Scelimenini Hancock, 1907; selected genera: "incertae sedis" Subfamily Tetriginae. Auth.: Serville, 1838  Tribe Dinotettigini Günther, 1979 Tribe Tetrigini Serville, 1838 Tribe unassigned: Subfamily Tripetalocerinae. Auth.: Bolívar, 1887 Tripetalocerinae was originally described by Bolívar in 1887 to gather all the Tetrigidae genera of the old world with widened antennae (e.g. "Arulenus, Discotettix, Hirrius, Ophiotettix, Tripetalocera"). This subfamily today includes only two species in two genera - "Tripetalocera" (with one species) from India and Borneo and "Tripetaloceroides" (with one species) from Vietnam and PR China. Members of the subfamily are characteristic within Tetrigidae by massive antennae built up of only eight segments (other Tetrigidae have usually 11-16, Batrachideinae 18-22). Till recently, the subfamily  included two tribes - Tripetalocerini and Clinophaestini (including "Clinophaestus" and "Birmana"), but the later was moved to the subfamily Metrodorinae due to similarity to Ophiotettigini. Subfamily unassigned. Criotettigini. Auth. Kevan, 1966 Thoradontini. Auth. Kevan, 1966