This enigmatic species is known only from the type material that was collected on Isla Isabella, Galápagos Islands, it appears not to be related to any other Central- or South American species of its genus.
The species is a leafless, middle-sized shrub with several stems that bear clusters of branches on their upper nodes. 
 I. Loren Wiggins; D. M. Porter; E. F. Anderson: Flora of the Galápagos Islands. Stanford University Press 1971
The Ankarafantsika Spurge, a multi-branched, climbing plant, was restricted to a locality in northwestern Madagascar, it is known exclusively from two collections, one made in 1900, and the second one in 1920.
The locality were this species was found, are now highly degraded, it was never found since 1920 and is thought to be globally extinct.
The Red-veined Copperleaf was endemic to the island of Saint Helena; the litte tree, which, for its beautiful red male flower spikes, which hung in great profusion from every twig, the islanders named string-tree or stringwood, was restricted to the elevated parts of the southern slopes of Diana’s Peak.
The species reached a size of about 2 m in height; its red-veined leaves were 5 to 7 cm long and 3 to 5 cm wide, the male inflorescences were about 20 cm long, the flowers were red while the female flowers were rather inconspicuous.
The last individual was found by John Charles Melliss, an amateur naturalist that lived on Saint Helena.:
“The last plant I saw of it in the island was one that had been transplanted to Oakbank about twenty years ago. It grew to a small tree about eighteen inches high, and blossomed and seeded freely, but is no longer there.” 
This last known individual died in about 1870.
 John Charles Meliss: St. Helena: A Physical, Historical, and Topographical Description of the Island, including its Geology, Fauna, Flora, and Meteorology. London: L. Reeve & Co. 1875
Wilder’s Copperleaf was restricted to Rarotonga, the largest of the Cook Islands, and was scientifically described in the year 1931.
The species was a mostly unbranched, about 2 m tall shrub, with long-stemmed, about 30 x 20 cm large leaves. It was monoecious, with plants producing either only female or male flowers, which appeared at the tops of the branches, the female flowers in short upright inflorescences, the male flowers in long, drooping ones.
The Night-blooming Cestrum (Cestrum nocturnum L.), a plant introduced to Rarotonga, is known for displacing other plant species by forming dense impenetrable thickets, and is thought to be one of the invasive species that are responsible for the extinction of Wilder’s Copperleaf.
The Elk-horned Spurge, described in 1887, is, or was, restricted to central Madagascar. It is a succulent, multi-branched shrub or treelet, its upright growing branches are about 0,3 to 0,5 cm in diameter.
The Elk-horned Spurge is not fully researched and might turn out to be not a valid species at all.
The Quito Spurge is known only from two collections, the first one from 1862 and the other one from 1887, the species was found in mountain forests at elevations of 2500 to 3000 m on the western slopes of the Andes.
The species was never recorded since and is very likely already extinct.
Waianae Spurge (Euphorbia celastroides var. tomentella)
This plant, one of eight varieties within this species, was endemic to the Wai’anae Range on the island of O’ahu, Hawai’i Islands.
It is now considered extinct.
The several varieties of some of the Hawaiian spurge species (Euphorbia celastroides Boiss., Euphorbia multiformis Hook. & Arn., Euphorbia remyi A. Gray ex Boiss., Euphorbia skottsbergii Sherff) are not accepted by all botanists and are sometimes included within the respective nominate forms.
This species is known exclusively from the type collection made in 1927 in the evergreen forests in the area around the two rivers Mangoro and Nosivolo at Madagascar’s east coast.
The species appears to have never been found since, and since the type locality is now highly degraded, it may be completely extinct.
There exists the chance that Tardieu’s Spurge is identical with another spurge species, Mangelsdorff’s Spurge (Euphorbia mangelsdorffii Rauh.), a species that is quite well known and often kept in cultivation.
Pedicellate Broom Spurge (Amperea xiphoclada var. pedicellata)
This variety of the Broom Spurge (Amperea xiphoclada (Sieber ex Spreng.) Druce) is known only from the type material that was collected near Sydney, New South Wales; it differs from the nominate form (see photo below) by the prominently pedicellate female flowers.
Since this form was never found since, it is considered extinct.
The Chittagong Croton is, or probably was, a small tree that was found once in 1939 at a place named Myanimukh on a slope of a forested hill in the Chittagong Hill Tracts, a province in eastern Bangladesh.
The species was described in 1983; it has never found since the type collection and might well be extinct.
This species was described in 1887, originally as Euphorbia daphnoides Baill., however, this name was already used for another species, so the species was redescribed in 1921.
The species was apparently restricted to the Ambavatoby Bay at the north coast of Madagascar.
Unfortunately I could not found any more information about this species.
 Thomas Haevermans; Germinal Rouhan; Wilbert Hetterscheid; Marc Teissier; Karim Belarbi; Xavier Aubriot; Jean-Noël Labat: Chaos revisited: nomenclature and typi ﬁ cation of the Malagasy endemic Euphorbia subgenus Lacanthis (Raf.) M. G. Gilbert. Adansonia sér 3. 31(2): 279-299. 2009