Taxonomy & Evolution
1 - Taxonomy
2 - Butterfly Families and subfamilies
3 - What is a species ?
4 - Evolution and Speciation
5 - Lepidoptera and the Evolutionary table
6
- Butterfly World Census
Taxonomy
- the
classification of organisms by presumed relationships
The Linnaean System
Before
the advent of scientific nomenclature, confusion reigned :
Example
1 - The butterfly known in Britain as the Camberwell Beauty has in
past times been called the Grand Surprise, the Willow Beauty and the
White Petticoat. In the USA it is called the Mourning Cloak. In Europe
it has common names in several different languages.
Example
2 - The two butterflies known to early entomologists as the Selvedged
Heath Eye and the Golden Heath Eye were later discovered to be the
male and female of a single species which was initially called the
Gatekeeper but is now called the Small Heath. The original name
Gatekeeper is now applied to an entirely different species which has
variously been known as the Hedge Brown, Hedge Eye and Large Heath.
The name Large Heath however is now used for an entirely different
species that was previously known as the Manchester Argus, or Marsh
Ringlet !
The
Swedish naturalist Carl von Linn� ( Carolus Linnaeus ) decided to put
an end to this confusion. He realised that an internationally
recognised name was needed for every creature and plant, and that
every organism should be classified according to it's relationship
with other organisms. In 1735 he launched the Systema Naturae, a
catalogue of the names of all known animals and plants. Later, in 1758
came the 10th edition of Systema Naturae, which is regarded as the
starting point for the current system of classifying animals and
plants by family, genus and species.
Originally Linnaeus placed all butterflies and moths in the same genus
Papilio. Later it was realised that there
was a need to divide this genus, so as to distinguish groups with
different characteristics. Since the time of Linnaeus many thousands
of new species have been discovered and described by scientists, and
hundreds of genera have been created to accommodate them.
Every
known taxon is designated a binomial ( two-word ) name derived from
Latin or Greek roots. An example is the Common Blue butterfly
Polyommatus icarus :
The Common Blue was designated by Rottemburg in 1775 as
Polyommatus icarus. The first
part of the name means 'many spotted'. It
refers to the distinctive markings on the underside of the
wings of all species in the genus
Polyommatus. The name icarus
refers to a character in Greek Mythology. According to legend
Icarus and his father Daedalus were imprisoned in the
Labyrinth with a terrible creature, the Minotaur. In order to
escape, Daedalus fashioned a pair of wings for himself and his
son, made of feathers and wax. Before they took off from the
prison, Daedalus warned his son not to fly too close to the
sun. Icarus unfortunately became so overcome by the excitement
of being able to fly that he forgot his father's warning. He
got too close to the sun and his wings melted. He then fell
into the sea in the area which now bears his name, the Icarian
Sea near Icaria, an island southwest of Samos.
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Common Blue, Polyommatus icarus showing
the "many-spotted" underside �
Adrian Hoskins
Scientific names should always be written with the genus, species and
subspecies italicised, then the author's name and the date the
description of the taxon was first published.
Thus
the Common Blue is called :
Polyommatus icarus icarus
ROTTEMBURG, 1775
The taxonomic hierarchy
The
Linnaean System divides the Animal Kingdom into groups called phyla.
The phylum Arthropoda i.e. those animals with jointed limbs and a
hard exoskeleton, is divided into several classes. Among these are
the Crustacea which includes crabs, lobsters, shrimps & woodlice.
Other classes include Chilopoda ( centipedes ), Diplopoda (
millipedes ), Arachnida ( mites, spiders & scorpions ) and the
Insecta ( insects ).
The class
Insecta includes over 75% of all animal species. It is divided into
several super-orders, one of which is Amphiesmenoptera. The latter
is split into 2 orders - Trichoptera ( caddisflies ) and Lepidoptera
( butterflies & moths ). These 2 orders share a common ancestor,
Necrotaulidae, and have many features in common, e.g. their wing
venation is fundamentally similar, their wings are covered in setae
( modified to form scales in Lepidoptera ), and their larvae have
mouthparts with structures and glands modified to produce silk.
The table below shows Polyommatus icarus
in relation to the rest of the Animal Kingdom :
Kingdom |
Animalia |
Animals |
Phylum |
Arthropoda |
Joint-limbed invertebrates |
Class |
Insecta |
Insects |
Sub-Class |
Endopterygota |
Insects
with a 4 stage lifecycle : ova / larva / pupa / imago |
Superorder |
Amphiesmenoptera |
Trichoptera ( caddisflies ) & Lepidoptera |
Order |
Lepidoptera |
Butterflies, moths & skippers |
Sub-Order |
Ditrysia |
A division based on genitalia characteristics |
Super-Family |
Papilionoidea |
Scudder butterflies |
Family |
Lycaenidae |
Gossamer-winged butterflies |
Sub-Family |
Polyommatinae |
Blues |
Tribe |
Polyommatini |
Ciliate Blues |
Sub-Tribe |
- |
no sub-tribe has been allocated for
the genus Polyommatus |
Genus |
Polyommatus |
Many-spotted Ciliate Blues |
Sub-Genus |
- |
no
sub-genus has been allocated for the species
icarus |
species |
icarus |
Common
Blue |
subspecies |
mariscolore |
Irish sub-species of icarus |
Author |
ROTTEMBURG, 1775 |
the taxonomist who
described the species |
Lepidoptera
About
7% of all life forms on Earth are members of the Order Lepidoptera -
the butterflies, skippers and moths ( indicated in orange ) :
The
Lepidoptera comprises of about 174,250 known species ( this only
represents a fraction of the species in existence, as many more
await to be discovered and described, especially among the tropical
"micro" moth families ). The classification of Lepidoptera is under
constant revision, but they are currently divided into 126 families,
7 of which are colloquially known as butterflies :
Family |
subfamilies |
Hesperiidae |
Heteropterinae, Hesperiinae,
Pyrginae, Pyrrhopyginae, Megathyminae, |
|
Coeliadinae, Trapezitinae |
Papilionidae |
Papilioninae, Parnassiinae,
Baroniinae |
Pieridae |
Pierinae, Coliadinae, Dismorphiinae |
Lycaenidae |
Lycaeninae, Polyommatinae,
Theclinae, Curetinae,
Poritiinae, Miletinae, Lipteninae,
Liphyrinae |
Riodinidae |
Riodininae, Euselasiinae |
Nymphalidae |
Nymphalinae, Satyrinae, Morphinae,
Charaxinae, Apaturinae, Limenitidinae, |
|
Biblidinae, Cyrestinae,
Heliconiinae, Danainae, Libytheinae |
Hedylidae |
Hedylidae - 'moth butterflies' are
not divided into subfamilies |
Butterflies by day and moths by night ?
It is
wrong to think of butterflies and moths as being different. The
families which we call butterflies are generally those with brightly
coloured day-flying species. There are however hundreds of moths
among the families Zygaenidae, Arctiidae and Uraniidae which are
also brightly coloured and day-flying. Conversely there are many
butterflies among the Hesperiidae, Satyrinae and Brassolini that are
very dull and inconspicuous, and would be dismissed as moths by most
people.
Another "fact" often quoted is that butterflies always have clubbed
tips to their antennae, but that moths never do. The colourful
day-flying Zygaenidae moths however do have swollen tips to their
antennae, and the huge day-flying Cane-borer moths ( Castniidae )
possess clubbed antennae just like those of butterflies!
Perhaps
even more surprising is the fact that many butterflies fly at night
as well as during the day, particularly in the tropics. Examples
include the Caligo Owl butterflies,
Melanitis Evening Browns and certain
Riodinids. Examples from temperate regions include the Red Admiral
Vanessa atalanta and the Monarch
Danaus plexippus both of which
regularly fly into moth traps in the middle of the night.
The 35 species of the family Hedylidae are
nocturnal and moth-like in appearance. The early stages however have
many butterfly-like characteristics. The eggs for example are
structurally closer to those of Pieridae and Nymphalidae than to
moth eggs. The caterpillars have horn-like processes like
Apaturinae, a bifid tail as found in Satyrinae, and secondary setae
as found in Pieridae. They also have an "anal comb" used for
expelling droppings - a characteristic of the Hesperiinae. The pupae
likewise have structural characteristics more representative of
butterfly pupae, and are secured to the substrate with a silken
girdle, just like those of the Pieridae and Papilionidae.
Taxonomic revision
Taxonomy
is not an exact science. It relies on suppositions about the
relationships between various species, and about their evolutionary
ancestry. Because of this, the classification ( and the scientific
names ) of butterflies and moths are under constant revision. New
techniques such as microbiology, phylogenetics, DNA sequencing, and
the study of larval morphology regularly shed new light on the
relationships between species. This increasing knowledge regularly
results in the necessity to revise classification. Sometimes it is a
simple matter of relocating a species to a different genus. On rare
occasions however it may require that a genus, tribe or even an
entire subfamily be migrated from its familiar home and relocated
into another family or superfamily.
The
inexact nature of taxonomy, and the fact that it relies on opinion
rather than fact, unfortunately means that scientists often find
themselves in disagreement about which genus a particular species
belongs to, or whether two or more butterflies with very similar
characteristics should be classified as separate species or as
subspecies.
Occasionally a taxonomist will believe that he or she has discovered
a "new to science" species and will describe it's characteristics
and publish a name for it. Later however they may realise that the
species has already been described and named by someone else. In
such cases the oldest name takes precedence, and the newer name is
discarded, and listed as an invalid ( junior ) synonym.
The
reclassification of
Bia actorion
As
our knowledge grows and relationships between different taxa
are more clearly understood it sometimes becomes necessary for
a butterfly to be reclassified under a different genus, or
even under a different subfamily or family.
One of the most well known examples of this phenomenon is
Bia actorion, a neotropical
species originally described by Linnaeus in 1763 as
Papilio actorion and placed in
the then all-embracing family Papilionidae. During the next
few years as many more species were discovered it became clear
that a single genus was inadequate. It was ordained that the
original genus Papilio should be
used exclusively for Swallowtail butterflies, and that new
genera would need to be created to house all other species.
Consequently in 1819 H�bner created the genus
Bia
to accommodate actorion. H�bner
believed that actorion was
related to the "Browns" of Europe, so he placed
Bia in the Satyridae, which was
then regarded as a family of equal rank to the Nymphalidae.
In
the 20th century Wahlberg and other taxonomists concluded that
the Satyridae, Brassolidae, Amathusiidae, Acraeidae,
Heliconiidae etc all shared a number of common
characteristics, and that they should thus all be relegated to
become subfamilies of the Nymphalidae.
For a few years
Bia actorion - also known for a while as
Napho actoriaena - was retained
in the Satyrinae, but further studies determined that it
really belonged to the Brassolinae. Currently
Bia actorion and it's close
relative Bia peruana are
classified as members of the subtribe Biina, which is placed
in the Brassolini - a tribe within the Morphinae, which is now
considered to be a subfamily of the greatly enlarged
Nymphalidae !
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Bia actorion, Manu Biosphere Reserve,
Peru �
Adrian Hoskins
How scientists
describe and name new species
When someone thinks they've discovered a new species, they have to
provide sample specimens to taxonomists for analysis. By comparing
the structure of the wing venation, genitalia and various other
anatomical features to that of currently known species, taxonomists
can then easily ascertain the genus, and decide whether the
specimens represent a previously known species or a new one.
If there are significant differences between the new species and all
previously known species it may be regarded as sufficiently unique
to deserve the creation of a new genus. If on the other hand its
anatomy is close to that of other species it will be placed in an
existing genus, and will be allocated a new species name in
recognition of its uniqueness.
New species are given a
Latinised name and a full scientific description, which are
published in a recognised scientific journal.
The origin of scientific names varies enormously. Some species are
named after Greek gods, some are named after the place where the
butterfly was discovered or named in honour of some eminent
entomologist. Names can also be descriptive of the colour, pattern
or wing shape.
The Charismatic
Metalmarks
Taxonomists are not
usually renowned for having a great sense of humour, but amongst their
more hilarious moments they have colluded to provide us with some
entertaining scientific names. Hence there are a pair of metalmarks
from Colombia, named by Hall & Harvey in 2002 as
Charis ma and Charis matic. Both
have now been renamed rather less attractively as
Detritivora ma and
D. matic. The new genus name refers to the fact that the larvae
feed on decaying leaves and other detritus on the forest floor.
The world's most
dismal butterfly ?
Sometimes it
can be difficult to think up names for some of the more mundane
looking species, particularly for the hundreds of near-identical
dull brown skipper species found in the neotropics. In 1997 Austin
was apparently so totally unimpressed with his latest discovery that
he gave a new Mexican species the unfortunate name
Inglorius mediocris, which needs little
translation !
Below is an example of a scientific description :
Inglorius
Austin, new genus
Type species:
Inglorius mediocris
Austin, new species
Description. Palpi slender, third segment straight, protruding
well beyond second segment, about equal to length of dorsal edge
of second segment; antennae long, extending beyond end of
forewing discal cell, nearly 60% length of forewing costa, black
with pale ochreous beneath distad and below club; club just over
1/4 (28%) antennal length, bent to apiculus at thickest part,
apiculus length about 2x club width, nudum grey, of 12 segments
(3 on club, 9 on apiculus); forewing discal cell slightly
produced, 75% length of anal margin, origin of vein CuA2 nearer
to CuA, than to wing base, hindwing discal cell just over 1/2
wing width; mid tibiae with four fine spines on inner surface
and single pair of spurs, hind tibiae with two pairs of spurs;
forewing produced with slight concavity between CuA! and 2A;
hindwing convex anteriorly, somewhat concave between CuAj and
2A; no apparent secondary sexual characters. Male genitalia with
short tegumen; uncus longer than tegumen, undivided, and
hood-like over gnathos; gnathos as long as uncus, divided,
extending laterad of uncus in dorsal view and as rectangular
flaps mesad in ventral view; vinculum sinuate; saccus short;
valva very long, ampulla/costa long and sloping somewhat
downward caudad, harpe long, roughly triangular ending in an
inward turned point caudad, dorsal margin undulate, weakly
serrate cephalad; aedeagus tubular (anterior portion missing),
caudal end expanded terminally in lateral view, no apparent
cornutus. |
More 'creative' species names
The
entomologist Burns was clearly having a mental block when it came to
naming his new skipper - Cephise nuspesez
( pronounced "new species" ). Just to prove that weird humour is not
confined to entomologists, here are some of the equally odd
scientific names given to other creatures :
Abra cadabra |
a
species of clam - with magical properties ? |
Agra vation |
an "aggravating" carabid beetle |
Cyclocephala nodanotherwon |
a species of scarab
beetle - "not another one !" |
Heerz lukenatcha |
a
species of braconid wasp - "here's lookin' at ya !" |
Kamera lens |
a protozoan - shaped
like a "camera lens" |
Pulchrapollia |
an extinct parrot, translates as "Pretty Polly" |
The
above show both creativity and humour, but in 1969 when Spencer had
the task of inventing names for new flies, he invented possibly the
most boring series of species names in existence, by naming his
discoveries sequentially, as
Ophiomyia prima,
secunda,
tertia,
quarta,
quinta,
sexta,
septima,
octava,
nona,
undecima, and
duodecima (
Latin for "first",
"second", "third", etc ).
Dybowski went to the
opposite extreme when he proposed the ludicrously unpronounceable
name
Gammaracanthuskytodermogammarus loricatobaicalensis
for a new Amphipod
in 1927. It would have been the world's longest scientific name, but
luckily common sense prevailed and the name was rejected by the
International Commission for Zoological Nomenclature.
The
honour of having the longest scientific name actually approved by
the ICZN actually goes to a species of Stratiomyid fly -
Parastratiosphecomyia stratiosphecomyioides.
The
shortest appears to be that of a Vespertilionid bat -
Ia io, although there is a thrip with a
single-letter species name - Plesiothrips o
!
More strangely
named butterflies
here.
Former common
names of British butterflies
here.
More
fascinating scientific names -
Earthlink Taxonomic Puns
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