I have drawn a quick map of Terra Altera, as she may 
be known about 1870? 80?

It stretches from Easter Island to near the Chatham 
Islands, and extends off to the southwards for an 
unknown, or at least unmapped, distance.

From W to E, the known coastal regions of any 
importance are:

Moriori Land. In our world, the Moriori are the more 
or less extinct aboriginal inhabitants of the Chatham
Islands. In Terra Altera, they are a very numerous and 
curmudgeonly maori-like people occupying a slab of 
coast between 40 and 50 °S and an unknown distance 
inland. They share their land with moas, marsupial 
saber-tooth tigers, and a kind of hippopotamus-like 
monotreme, but all naturalists that have gone to peer 
at these things have been eaten.

Ponsonby Land, Maria Theresa Land, New Saxony - 
“German West Altera” These areas  are recognised in 
Europe as German territory, but no european 
has ever travelled by land between the few marginal 
settlements; almost the entire population disappeared to 
unknown parts when the first explorers arrived, leaving 
their mysterious cities completely intact. Here the 
Volga-wide Gunther Fluck river, a possible highway
 to the interior, empties into the Pacific Ocean, but 
gigantic cataracts about a hundred miles upstream have 
foiled all explorers.

Rapanora, Marotiri
These coasts are inhabited by polynesian peoples and 
governed by the French in a desultory maxim-gun 
wielding kind of way. All expeditions into the interior 
have been rebuffed by enormous mountain ranges.
Santa Clara, an island at about 29°S 148°W, was 
settled by shipwrecked Portuguese mariners about two 
hundred years before the continent was 
properly discovered.

French Gutuland, British Gutuland
The Gutus are a race unlike any other in the world, 
sort of like bushmen, sort of like pygmies, and 
rather like Yorkshiremen- mendacious and easily 
cowed, they do not like to travel far from their 
coastal homeland. Port Moriarty is on the Cuthbert 
River in British Gutuland.

Albert Land, Pitcairn Land, Ducie Land
Together these form the British Crown Colony of 
Terra Altera. Impassable mountains rise not far 
inland, and the natives are sort of polynesian. 
There was/is probably some remote district ruled by 
descendants of Bounty Mutineers.  I think the 
climate in the subtropical zone gets drier the 
further east you go, so that it quite arid by the 
time one gets to...

Chester Alan Arthur Land
A huge American ambit claim made in the last 
decade or so, extending E from 122°W.  It 
incorporates Easter Island and its large adjoining 
territory sharing the same culture, Tierra Pascua, 
which was originally a Bolivian Protectorate. Again, 
wherever expeditions have headed inland they met
impassable mountains. The Pascuans claim to have 
once paid tribute to a mysterious “God King” 
dwelling beyond the mountains. 

Selkirk Land, Beatrice Nash Land, Burford Land
Mountainous fjordy bits, getting colder and wetter, 
inhabited by Yaghan-like savages. There are indications 
that Burford Land may be more or less flat, and covered 
with endless tracts of nothophagus forest; there are
 rumours of strange beasts, unknown to science...