CONSERVATION
The Changing Taxonomy
of East Africa’s Reptiles
STEVE SPAWLS
was born in London but
brought up in Kenya.
A science teacher
by profession, he has
published a number of
books and papers on
Africa and its reptiles.
L
ast week I received an
enthusiastic e-mail from a
herpetologist friend. ‘The
molecular data…’ he wrote excitedly,
‘indicates that green mambas of South
Africa are a different species from those
of eastern Africa, and we shall be able
to give them a new name…’ I had to
suppress an internal groan. Another
taxonomic name change coming up.
Taxonomy is the science of the
classification of organisms. It involves
describing species, with a scientific
name (usually Latin, but not always; a
Tanzanian frog was given the scientific
name Churamiti maridadi) and saying
where they fit in the order of things.
Living organisms are given a twopart scientific name; the first name
is the genus, the second the specific.
Some may merit a third name, the
subspecific. Consider the true African
vipers; generic name Bitis. The puff
adder has the specific name arietans,
so all puff adders go under the scientific
name Bitis arietans. And a subspecies,
found in the dry country of the Horn
of AFRICA, has the full name Bitis
arietans somalica; the Somali puff
adder.
There are few taxonomists, many
organisms to name, frequent changes
and much controversy. There always
has been. Carl Linnaeus published his
definitive version of the taxonomists’
bible, Systema naturae, in 1758, and
wrangling has persisted ever since.
African biologists are bedevilled by
taxonomic controversies. Is the African
elephant a single species, or two? Why
have they changed the generic name
of African acacias? Is the olive tree in
Kenya’s highland forests a full species,
Olea africana, or is it just the European
olive, Olea europea?
You have got to give organisms
scientific names to avoid confusion.
Otherwise, you cannot write a faunal
or floral list for a conservation area, or
say what species your research is on.
Consider that beautiful and deadly tree
of rocky land known in Kenya as the
Desert Rose or Mdiga, in other parts of
Africa it is called the Sabi Star, the Mock
Azalea, the Impala Lily or the Elephant’s
Foot. Botanists avoid confusion by
referring to it by its scientific name;
Adenium obesum. But organisms that
some taxonomists regard as a single
species may be regarded by others
as representing more; Kenya’s Greyheaded Sparrow is described in one
excellent field guide as a single species,
Passer griseus, in another equally good
guide it is said to be a complex of five
species. As the leading geneticist Steve
Jones has put it, what to some is mere
variety is granted its own identity by
others.
What defines that identity? It used
to be the morphology; the shape, size,
South African green mamba
36 SWARA APRIL - JUNE 2013
www.eawildlife.org
CONSERVATION
Originally Mabuya
maculilabris, now
Tracylepis maculilabris,
vivid coastal specklelipped skink
colour and anatomy. In the last 30
years, the taxonomists have gained
more tools for the toolbox. One is
numerical taxonomy; numbering
various character states and seeing
how they cluster together. But the
most powerful is molecular taxonomy;
analysing the biological molecules, in
particular the sequences of the four
bases in deoxyribonucleic acid, the
DNA. Cells have two sorts of DNA, that
found in the nucleus – the molecule
of inheritance – and that found in
the energy-making organelles called
mitochondria (and it was this stray DNA
that led the brilliant and controversial
American biochemist Lynn Margulis
to suggest that mitochondria, now an
integral part of the cell, actually started
life as separate bacteria).
The procedures and terminology of
molecular taxonomy are dense and
complex, but the principle is beautifully
simple; you look at two matching
sequences of bases from different
organisms. The more closely the base
sequences match each other, the more
closely the two organisms are related.
New information from the molecules
has thrown a spanner into traditional
taxonomic arrangements. With some
organisms, the proposed relationships
thus revealed are furiously resented.
Birds are a case in point; in their
East African Gaboon Viper
www.eawildlife.org
forward to their Guide to the Birds of
Africa, Ian Sinclair and Peter Ryan
state, defiantly, that their plates are in
traditional sequence, not evolutionary,
due to the resistance among birders
to the new taxonomy. Apart from
proving unpopular relationships; the
new molecular taxonomists have upset
traditionalists for two main reasons;
their elevation of subspecies, or even
just morphs, to full species, and
their creation of new genera for any
evolutionary line that has split away
from the original.
In 2001, myself and three
herpetological friends published a field
guide to East Africa’s reptiles (‘A Field
Guide to the Reptiles of East Africa;
Spawls, Howell, Drewes and Ashe; A
and C Black). It looks as though we got
in just before molecular taxonomy took
off. In the last 10 years, the machines
and kit for sequencing DNA have
become much cheaper and more widely
used, and the technology more efficient.
And all you need is a tissue sample; the
work can be done in the laboratory,
not the field. The new molecular
taxonomists are having a field day.
SWARA APRIL - JUNE 2013 37
CONSERVATION
How does this affect Kenya’s reptiles?
Consider the skinks, originally of
the genus Mabuya, chunky lizards
of which some ten species occur
in Kenya, including the extremely
common striped skink, Mabuya
striata. Molecular analysis of DNA
indicated that these skinks rafted
westwards across the Atlantic from
Africa twice, but the original scientific
name, Mabuya, applied to an American
species. So all African Mabuya have
now been reclassified, in the genus
Trachylepis. What about chameleons?
All regular African chameleons
(excluding the Stump-tailed pygmy
chameleons) were placed in the genus
Chamaeleo, and why not? They share
so many similarities (prehensile and
The Mt Kenya hornless
chameleon, now
Kinyongia excubitor
38 SWARA APRIL - JUNE 2013
Kenya’s most widespread skink,
striped skink Trachylepis striata
unshedable tail, rotating eyes, similar
size, often green) that they must have
had a common ancestor. But molecular
evidence indicates that a group of East
African montane chameleons (including
the endemic Mt Kenya Hornless
chameleon, Chamaeleo excubitor)
belong to a separate ‘clade’, ie. they
have a common ancestor that doesn’t
include other chameleons. They have
been placed in a new genus, Kinyongia,
an excellent name (kinyonga is Swahili
for chameleon), a move I described in
an earlier issue of SWARA (vol 30:1).
But laypersons may be confused. What
of other species? The brightly-coloured
Agama lizards are being studied by the
German herpetologist Philipp Wagner,
and he has split the common species
Agama agama into a number of forms.
Molecular data indicate that the Lake
Tanganyika Water Cobra, Boulengerina
annulata, should not be in its own
genus, but is, in fact, a true cobra, and
it has been moved into the genus Naja.
And in the near future, most of Kenya’s
Little half-toed or Hemidactylus
geckoes will be receiving new names;
work by the Czech herpetologist Tomas
Mazuch indicates they are a far more
complex group than was thought.
Consider the Gaboon Viper, that huge
spectacular snake of African forests.
It occurs in two disjunct populations;
from Ghana westwards to Guinea, and
from Nigeria eastwards to Kenya. The
West African form has a single narrow
stripe behind the eye and big horns on
the nose, the central and East African
form has a broad double stripe behind
www.eawildlife.org
CONSERVATION
West African Gaboon Viper
In a way this is inevitable; an ultimate
reductionist would say that there is
only one species - life - since all living
things started from a common ancestor
the eye and tiny horns on the nose.
Traditional taxonomists designated the
two forms as subspecies; Bitis gabonica
rhinoceros, the western form, and B.
g. gabonica, the eastern form. But
molecular work by a team of German
taxonomists led them to elevate the
two subspecies to full species. But
realistically, the two ‘species’ of Gaboon
viper do not differ from each other to
the extent that say, a puff adder differs
from a Gaboon viper.
In a way this is inevitable; an ultimate
reductionist would say that there is only
one species – life- since all living things
started from a common ancestor. All
that varies is the time that the various
www.eawildlife.org
lines have been separated. Look for
groupings. The common ancestor of
the puff adder and Gaboon viper are
further back in time than the common
ancestor of the two species of Gaboon
viper. In giving names, we are trying to
compartmentalise a continuum.
It is also worth remembering that
taxonomy can lead to immortality, of
a sort. The name of the author, and
the new form, if valid, persists forever.
Five hundred years from now, when
knowledge of today’s politicians and
pop stars has long since faded, people
will look at Kenya’s Big brown spitting
cobra, Naja ashei, named by Broadley
and Wuster, and think, who were
James Ashe, Wolfgang Wuster and
Don Broadley? This immortality has
attracted some oddballs into the field.
The maverick Australian herpetologist
Raymond Hoser, working with minimal
data, has named and renamed dozens
of prominent snakes species and
genera. Some might say he has done
herpetology a favour, in that his changes
– Hoser has an undoubted knack of
spotting a clade – has so incensed
mainstream taxonomists that they
have decided to stick with traditional
groupings, because if they want to put
the new group in a clade, the rule of
priority insists they must use Hoser’s
names, since he named them first!
And in the meantime, our book
needs updating. As do all books listing
living things. It may be infuriating.
But like all sciences, the state of the
knowledge moves on. And that has to be
a good thing. But you have to read the
literature…
SWARA APRIL - JUNE 2013 39