Sunday, 14 December 2014

New Mammal Species 2014

Waiomys mamasae
New species of animal are discovered every day. That isn't hyperbole; I mean it literally. I'm not sure of the exact number of new species that were named last year, but it's in the thousands, and likely a five-figure number, at that. This is, you'll note, rather a lot.

The great majority, of course, are insects. "An inordinate fondness for beetles" and all that. Most of the ones that aren't are also invertebrates, typically small things like mites, spiders, or crustaceans. When we do look at vertebrates, most of the new ones are fish, with amphibians and reptiles not far behind. For instance, looking at the new species described in the daily journal Zootaxa (by no means the only source for such things, although it is one of the largest) on Friday 12th December 2014, I count seven beetles, two flies, three crickets, a frog, a salamander, a gecko, and (unusually) a bunting.

In fact, new birds are, if anything, even more rarely described than new mammals. But while while new mammal species are not discovered that often, there are still several each year. So, for this, the last post of 2014, why not look back at some of the mammals that were officially described for the first time this year? This will not be, by any means, a comprehensive survey, just a sampling, and I'm not even counting the various new fossils that have been described, but nonetheless, here we go:

Bats, bats, bats

If you want to find a new species of mammal, your best bet is to look for something that isn't very easy to spot - most of the obvious ones have already been found. Being small and nocturnal is a big plus, so it's no surprise that bats frequently top the list when it comes to new mammal species. Better yet, go look in a jungle, where there tend to be less scientists, more obscuring foliage, and, as it happens, a greater richness of species to start with. (Those new species I mentioned from Friday's Zootaxa? The flies and the salamander are Chinese, everything else is from the tropics).

Having said which, a great many "new" species are not animals that nobody has ever seen before. In most cases, scientists had previously seen the animal, but just not realised that it was any different from the species already described. These days, it is not unusual for new species to be named primarily on the basis of their genetics, rather than anything physical. For example, a new species of long-winged bat from Morocco, Miniopterus maghrebensis, was described in May. The authors identified slight differences in its physical appearance and echolocation calls from the common bent-winged bat (M. schriebersii), but not enough to clearly distinguish the two - the sort of finding that might, at best, be enough to name a new subspecies. But genetic analysis showed that the two were sufficiently distinct that they can't have been interbreeding even where they lived together, and therefore had to be different.

Sometimes, however, physical differences are enough, although it may take quite a lot of statistical analysis to prove there isn't any overlap. This approach was used to identify two new species of yellow-eared bat from Colombia (Vampyressa sinchi) and Panama (V. elisabethae) in October. These, it turns out, inhabit higher altitude mountains than Melissa's yellow-eared bat (V. melissae), the name under which the specimens concerned had been filed in museums. Of course, your new species has a better chance of entering the textbooks if you can do both, as happened in November with  new species of pipistrelle from Laos and Vietnam (Hypsugo dolichodon) which has both larger teeth and a different genetic makeup than the Chines pipistrelle (H. pulveratus) with which it had previously been identified.

However, perhaps the most interesting new bat of the year is the golden myotis (Myotis midastactus) from Bolivia. This is a mouse-eared bat, one of a large group of over a hundred known species with representatives on every continent except Antarctica. One of those many species is the velvety myotis (My. simus), previously thought to be found across central and north-western South America, from southern Colombia to Paraguay and eastern Brazil. This was always a particularly distinctive bat, not least because of its velvety-soft reddish-brown fur, although its wing membranes are also a somewhat unusual shape compared with those of its relatives.

Back in 2011, however, analysis of some specimens showed that those in Bolivia looked rather different from those in the Amazon. There wasn't enough at the time to identify them as clearly different animals, but in August of this year, a more detailed analysis by Ricardo Moratelli at the Smithosonian provided the clinching evidence. So far as we know, they live only in Bolivia, but they can be visually distinguished from velvety myotises (and, indeed, from every other bat on the continent) by their bright golden fur. Indeed, the name "midastactus" translates as "Midas touch".

Just one more, though, before I leave the bats, and it isn't even a new species. In 2012, researchers Catherine Hughes and Julie Broken-Brow captured an unusual bat in Papua New Guinea. Earlier this year, they transferred the specimen to an Australian museum for a closer look, and successfully identified it as a New Guinea big-eared bat (Pharotis imogene). Which is significant, because that species was previously known from only a small number of preserved specimens collected back in 1890. Never having seen another one since, everyone had assumed they had gone extinct at some point in the early 20th century...


Moving away from bats, your next best bet for identifying a new mammal species is to look at rodents. Like bats, they're small, and often nocturnal, and, if we're honest, a lot of them do tend to look rather similar. Which means that, if you have the time to examine them in great detail, especially if you can also run genetic tests, it's entirely possible that you'll discover something new. It may, of course, take rather a long time, a lot of it involving carefully measuring the shapes of dozens of different skulls, but the chance is there.

Often, you find the genetic evidence first, and it's only once you've discovered that the creatures are indeed different at that level that you spot minor physical differences that go along with them. This happened with Fea's tree rat (Chiromyscus chiropus) in November, when genetic tests showed that specimens from Vietnam should probably be considered a separate species (C. thomasi).

Another example comes from a rather weird animal named the Chinese pygmy dormouse (Typhlomys cinereus), about which we don't really know much to start with. These aren't real dormice at all, and seem to be rather distantly related to any other "mouse-like" rodent. They only live in mountains around the Chinese-Vietnamese border, and few scientists have seen one alive. One of their unusual features is that they have tiny eyes, rather like those of moles, which suggests that they must spend a lot of time underground - which certainly wouldn't help in finding them. What's stranger, though, is that every other feature of their body, including a prehensile tail, suggests that they ought to be climbing animals. As far as we can tell, that's what they are, so are they so nearly blind? It's a mystery.

At any rate, there is only one species, and only one other species, the spiny dormouse, that belongs in the same family. However, as far back as the 1930s, it was suspected that there might be more. For most of the time since then, this other animal (T. chapensis), representing the forms on the Vietnamese side of the border, has been considered to be demoted to a subspecies. Not everyone agreed, and, this November, three Russian researchers published that seems to settle the issue, using genetic and physical evidence to raise what we should probably call the Vietnamese pygmy dormouse back to species level. It probably took so long because, frankly, few people had even heard of the animal.

Speaking of unusual animals, there are the semi-aquatic carnivorous rodents of Indonesia and the Philippines. Well, all right, "carnivorous" is a bit of a stretch, since they mainly eat insects, not red meat, but it'll do. Collectively termed "water rats", these are river-dwelling members of the mouse family, with clear adaptations to a semi-aquatic life, such as small ears, webbed hind-feet, and stiff whiskers. In June of this year, a new species fitting this description was announced from Sulawesi in Indonesia. It's quite clearly distinct from anything we have known before, so much so that it has been placed in an entirely new genus, and named Waiomys mamasae.

Unlike its fellow water rats, this animal, which as yet has no name in English, does not have webbed feet, and lacks some, but not all, of the adaptations we'd expect of a semi-aquatic animal. It clearly does spend a lot of time swimming in rivers, though, not least because that's what it was doing when they found it. It also had a stomach full of freshwater invertebrates, and nothing else, which is rather suggestive.

Sometimes, though, genetic analysis can cut both ways. Also in June, we had the publication of a genetic and morphological survey of tuco-tucos from the Bolivian lowlands. These are smallish, subterranean rodents, and, if it helps, they're related to degus. (No? Well, that's South American rodents for you). Anyway the study identified a total of four new species, most of them clearly distinct from the tuco-tucos we already knew about. But the study also concluded that one known species of tuco-tuco didn't actually exist at all and was just an example of one of the others. Still, that's three species up...

Sengis and Sakis

Two similar surveys this year have also uncovered some new non-rodent species. One of these, another June publication, examined sengis from southern Africa. Like rodents, sengis are small animals, and they're often known as "elephant shrews", although scientists tend not to use that term any more, since they aren't actually shrews. (Funnily enough, they're closer to elephants...) The sengi family was given a thorough description and species list back in 1968, and no more were discovered for a further 40 years. Two more were identified in 2008, although the chances are that there are plenty more that we haven't got around to yet.

Anyway, this new survey identified an odd specimen from northern Namibia as belonging to a previously unknown species, the Etendaka round-eared sengi (Macroscelides micus), which turns out to be the smallest sengi known, weighing only 28 grams (1 ounce). It lives, so far as we know, only on gravel plains, and, like the Maghreb long-winged bat mentioned above, we know that it's a distinct species partly because it doesn't interbreed with the Namibian round-eared sengi (Ma. flavicaudatus) despite having every opportunity to do so.

However, not every newly discovered species is something small like a bat, rat, or shrew. Saki monkeys live in Colombia, Peru, Bolivia, and Brazil, and while smallish as monkeys go, can still weigh up to 2 kg (4.4 lbs). Until July of this year, there were six recognised species of saki monkey. Then a huge survey, conducted by the International Union for the Conservation of Nature and the Species Survival Commission and published in two parts, looked at over a thousand museum specimens and photographs of wild animals in 28 countries to see how accurate this really was.

They identified no less than sixteen different species of saki monkey. Six we already knew about, and three we knew about, but had previously thought were just subspecies. Three more had been described ages ago, before 20th century researchers changed their minds and decided that they weren't anything special. The remaining five were completely new. So, in addition to the six rescued from varying degrees of taxonomic oblivion, welcome to:
  • Cazuza's saki (Pithecia cazuzai)
  • Isabel's saki (P. isabela)
  • Mittermeier's saki (P. mittermeieri)
  • Pissinatti's saki (P. pissinattii)
  • Rylands' saki (P. rylandsi)
  • Possibly the Jamari saki, as well, but there's not enough evidence to say it's definitely a species yet, partly because nobody could find a photo of a living one

And, of course...

I can't finish without mentioning the Araguaian boto (Inia araguaianensis), which I already talked about in February, a few weeks after its publication. Because it's inherently cool. But even that isn't alone, since, in July, we also had the announcement of the Australian humpback dolphin (Sousa sahulensis), a more conventional dolphin, distinguished by a "cape-like" patch of darker skin on its back, and that inhabits the waters between Australia and New Guinea.

Synapsida will return in the New Year. Merry Christmas!

[Photo by Kevin C. Rowe. Released under the Creative Commons Attribution License.]

No comments:

Post a Comment