Tonga

Birds found nowhere else include the Tongan Scrubfowl or Malau (flickr) (tongaturismo.info WM) and the Tongan Whistler (flickr) (eBird).

Reptiles known solely from Tonga include the 'Eua Forest Gecko Lepidodactylus euaensis (Google Books), the Tonga Robust Tree Skink Emoia mokolahi (iNaturalist) (ResearchGate), and the extinct Tongan Giant Skink Tachygyia microlepis (Smithsonian pdf), an endemic genus.

Marine fish unique to Tonga include the Blackfin Damselfish Amblyglyphidodon melanopterus (iNaturalist), the Swallowtail Fangblenny Meiacanthus procne (iNaturalist), the Green Canary Blenny Meiacanthus tongaensis (FishBase), the Black Foxface Siganus niger (reef builders), the Tonga Grouper Epinephelus chlorocephalus (FishBase), the Tongan Spiny Basslet Acanthoplesiops naka
(ResearchGate), the Tiger Dwarfgoby Eviota tigrina (FishBase), the Blackstreaked Blenny Salarias nigrocinctus (GBIF), the Linedfin Rockskipper Praealticus multistriatus (GBIF), the coralbrotulas Diancistrus alatus (ResearchGate) and Diancistrus manciporus (FishBase), the Tongan Sharpnose Puffer Canthigaster flavoreticulata (J-STAGE pdf), a tonguefish Symphurus maculopinnis (GBIF), and a snake-eel Ophichthus aniptocheilos (GBIF). A cutthroat eel Thermobiotes mytilogeiton (chess.myspecies.info) is an endemic genus.

Insects restricted to Tonga include a leaf beetle Rhyparida punctatissima (Harvard), a jumping shore beetle Babalimnichus (or Mexico) splendens (ResearchGate), the click beetles Dioxypterus tonga and Dioxypterus eua (both at BHL), the ants Colobopsis nigrifrons (AntWiki) and Strumigenys zakharovi (fig. 2d at Internet Archive), a cicada Aceropyga albostriata (fig. 1 at BHL), a planthopper Dystheatias periander (p. 11 of Bishop Museum WM pdf), a dragonfly Anax tonga (PLAZI), a damselfly Teinobasis fatakula (Lincoln Univ) (Zootaxa pdf), a cricket Cardiodactylus kraussi (Google Books), a katydid Oceaniphisis tongaensis (Fig. 96 of McGill Univ. pdf), a fruit fly Bactrocera facialis (PLAZI), and a barklouse Lepidopsocus euaensis (p. 5 of Bishop Museum WM pdf).

A butterfly Deudorix armstrongi (fig. 8 at BHL) has sometimes been considered a full species unique to Tonga. Endemic butterflies also include the subspecies Euploea lewinii lewinii (iNaturalist), Jamides carissima thomasi (iNaturalist), Doleschallia tongana tongana (fig. 3 at BHL), and Catochrysops taitensis hopkinsi (p. 19 of Bishop Museum WM pdf).

Endemic arachnids include the jumping spiders Chalcotropis insularis (fig. 26 at ZMMU pdf) and Sobasina magna (BHL), a crab spider Diaea tongatabuensis (fig. 86 at BHL), a long-jawed orb weaver Leucauge eua (fig. 2 at BHL), and a pseudoscorpion Tyrannochthonius eua (ZooKeys). Endemic land snails include Vatusila tongensis (BHL), Graeffedon pricei (GBIF), Thaumatodon euaensis (GBIF), Diastole tongana and Sinployea paucicosta (both on p. 105 of MACBIO pdf), Lamprocystis vavauensis (GBIF) (p. 88 of Bishop Museum WM pdf), Eua globosa (p. 4 of Bishop Museum WM pdf) (GBIF), Samoana cramptoni (p. 9 of Bishop Museum WM pdf), and Tuimalila pilsbryi and Tuimalila infundibulus (both at BHL). Metapheretima sergei is an endemic earthworm (fig. 1a at Taylor & Francis pdf).

Marine invertebrates collected exclusively in Tongan waters include the molluscs Calliotropis ptykte (Eddie Hardy), Bayerotrochus poppei (BHL), Depressizona axiosculpta (ResearchGate), Callochiton tongaensis (ResearchGate), Alviniconcha strummeri (IUCN), Oliva hilli (GBIF), and Diodora tongana (Eddie Hardy). Other invertebrates only known from Tonga include a squid Choneteuthis tongaensis (Tree of Life WM), the octopuses Octopus gorgonus (ResearchGate) and Abdopus undulatus (ResearchGate), a squat lobster Paramunida achernar (GBIF), a shrimp Laomenes (or Periclimenes) jackhintoni (BHL), and a soft coral Parasphaerasclera zanahoria (BHL). A barnacle Neobrachylepas relica (ResearchGate) (chess.myspecies.info) known only from a hydrothermal vent near Lau is the sole member of the family Neobrachylepadidae

Vascular plant species occurring naturally only in Tonga include a tree fern Cyathea euaensis (JSTOR), a fern Reholttumia (or Thelypteris) macroptera (GBIF), an orchid Robiquetia tongaensis (IOSPE WM) (p. 70 of Lankesteriana pdf), Phyllostegia tongaensis (JSTOR), Ixora yunckeri (GBIF), Pandanus amicalis (JSTOR), Pandanus tongatapuensis (JSTOR), Pandanus vavauensis (JSTOR), Psychotria euaensis (GBIF), Psychotria kaoensis (JSTOR), Plantago euana (GBIF), Oldenlandia debilis (JSTOR), Selaginella yunckeri (GBIF), and Syzygium crosbyi (JSTOR).

Trees known only from Tonga include a fan palm Pritchardia pacifica (PACSOA WM) which has also been introduced to Fiji and elsewhere, Atractocarpus crosbyi (p. 29 of MACBIO pdf), Casearia buelowii (iNaturalist), Podocarpus pallidus (RBGE) (POWO), Discocalyx listeri (CIEER WM), Pittosporum yunckeri (CIEER WM) (p. 123 of CEPF pdf), Phyllanthus amicorum (CIEER WM), Guioa lentiscifolia (ResearchGate), Dysoxylum tongense (CIEER WM), Arytera bifoliata (CIEER WM), Polyalthia (or Meiogyne) amicorum (CIEER WM), Xylosma smithiana (JSTOR), and Aglaia heterotricha (JSTOR) (IUCN).

Endemic lichens include Arthonia tongaensis (Wikispecies) and Parmotrema tongaense (fig. 7 at ResearchGate). Endemic non-vascular plants include the mosses Taxithelium tongense (GBIF) (BHL) and Campylopus ditrichiae (JSTOR).

Tonga is part of the Tongan Tropical Moist Forests terrestrial ecoregion (EoE) and the Polynesia - Micronesia biodiversity hotspot (Biodiversity Hotspots WM). For an overview of the natural history of Tonga see the National Biodiversity Strategy and Action Plan (CBD pdf). A 2011 list of endemic vascular plants is at (p. 7 of CEPF pdf).