A discovery map and a richness map are not the same object. The distance between them is the first thing to settle. Dating first descriptions by decade [1] reliably tells you where describing happened. Whether it also tells you where the species are depends on how much of the signal is effort: expeditions funded, museum drawers revisited, molecular tools turned on populations long filed as one animal. Australia's known reptile fauna moving from 376 species to 933 [6] is a 2.48-fold rise [2], and the authors' summary does not separate newly encountered animals from newly recognised ones. Those have different operational meanings; the first says go and look, the second says the list you already had was mis-sorted.
The scale helps. The four groups sum to about 30,700 species [1], and if nearly 40% of that catalogue was named between 1920 and 2020 [3], roughly 60% of it predates the study window entirely [3]. So the reshuffle is being driven by the newest two-fifths of the list, and it is that fraction which clusters, mostly in tropical rainforest in Brazil, Ecuador and New Guinea [4], with New Guinea's montane forests standing out for mammals [5].
One caution on arithmetic. The often-quoted figure that about 80% of plants and animals remain unstudied [11] and the 40% here have different denominators, one global and taxonomically mixed, the other four vertebrate classes on land, so multiplying them yields a number with nothing behind it. The plant backlog can be handled honestly on its own terms: as many as 100,000 unknown species [13] against more than 2,000 described a year [12] is about fifty years of work [4], assuming both the estimate and the rate hold.
Where this bites is the overlap. The regions the authors promote, Indonesia, the central Andes and Madagascar [7], and the cooler cloud and montane forests now hosting emerging reptile and frog hotspots [15], are the same places they describe climate change drying and warming [16] and land clearing eroding [17]. Updating the map delivers a longer list of contested ground, some of it holding species that will be gone before anyone names them [17].
The account here is the researchers' own, published on phys.org without a named journal or per-region effect sizes [20], so the turnover percentages [8][9] should be read as headline results awaiting the underlying paper. The framing they are pushing against is coarse in any case: seventeen megadiverse countries [10] is a country-level instrument being asked to do sub-national work, and with one in ten known mammals described only after the 1990s [14], any prioritisation inherited from before then is quoting a catalogue that has since grown. The useful inference for anyone spending survey money is that the places worth looking next are where the discovery curve is still climbing, a different question from where richness is highest today.
