Nauru
The Nauru Reed-warbler Acrocephalus rehsei (iNaturalist) (p. 80 of SPREP WM pdf) is found nowhere else.
An endemic subspecies of skink Emoia
arnoensis nauru (BHL)
(iNaturalist)
appears to actually represent an undescribed species (p. 68 of SPREP
WM pdf)
(p. 38 of CBD
pdf).
Insects known solely from Nauru include an tidal reef bug Corallocoris (or Omania) nauruensis (Discover
Life) (BHL)
and an undescribed leafminer moth of the genus Stigmella (p. 44
of SPREP
WM pdf). An ant Nylanderia
steeli (AntWiki)
(BHL)
described from Nauru (and not New Guinea as listed at AntWiki) appears
to be known solely from the type specimens.
Endemic land snails include Trochomorpha
insolata and Sturanya
subsuturalis (both on p. 45 of SPREP
WM pdf).
A barnacle Balanodytes
echinoideus
(WoRMS)
(ResearchGate)
is also known only from Nauru.
Although it has been claimed that a species of Phyllanthus might
be endemic, according to "The Flora of Nauru" (p. 21 of SPREP
pdf),
there are no endemic vascular plants and the claimed
endemic turned out to belong to the widespread Phyllanthus (or Emblica) societatis
(INPN).
For an overview of Nauru's biodiversity see (SPREP
WM pdf) and (CBD
pdf).
Nauru is part of the Eastern Micronesia Tropical Moist Forests
ecoregion (WWF
WM).