Dr Ron Atkinson lived
and worked in Toowoomba, so is familiar to some of our members. Accompanied by his
wife and daughters, he was made welcome on Friday night, and all listened with
great interest to his talk titled “The Twenty-first Century Spiderman”.
Enormous changes have been made within the field of spider taxonomy since the
19th century, and Ron outlined some of them.
A small spider field guide
with black and white illustrations published in 1968 is now almost completely obsolete.
Mascord’s “Australian Spiders in Colour”, published in 1970 and owned by some
of us, was a great improvement as images were in colour, but is probably now
50% incorrect. “A guide to the Spiders of Australia” by Volker Framenau and
others, full of information and containing excellent colour photographs was published
only two years ago but already needs revision.
The early scientists
describing Australia’s wildlife, including spiders and insects, used genera and
family names familiar to them from their work in the Northern hemisphere, but
they proved to be inaccurate, so changes were later made. Spiders once allotted
to the genus Epeira in Australia, are now placed in at least seven
different spider families. The common spider, Eriophora transmarina, the
garden orb weaver, has had nine name changes since it was first described in
1865.
Two funnel-web spiders
were named in 1873 and 1877 by Koch and Pickard-Cambridge respectively, Hadronyche
cerbera and Atrax robustus; now these have been expanded to more
than 30 Hadronyche species, many named for their locations – H.
lamingtonensis, H. alpina, H. Tambo, H. monaro. The three Atrax are probably
incorrectly named since taxonomic convention says that the first published
generic name for the group should apply for all others of the same kind of
spider.
Some spiders show strong sexual dimorphism,
like Mopsus mormon, a jumping spider. This was confusing for some
taxonomists, especially when more females than males are found, or vice versa,
and they were first thought to be separate species. There are various reasons
for these name changes. Early scientists working on spiders could only
communicate by letter, and mail services within Australia and overseas were of
course much slower than they are today. This meant that many species which were
identical were given different names by different people describing them. A
paper which was written in Eastern Australia and published in the UK might take
years before it arrived at the home of a biologist in a different part of
Australia.
Technology of course has
vastly improved since the 1870s. Taxonomists then relied on line drawings to illustrate
their descriptions, and some were much better artists than others. At that time
some did not realise what features were important - Funnel web spiders are
separated into species in some cases merely by bulge sand spurs on their legs
or by the shape of their palps or epigynum (sexual parts).
Microscopes have been
vastly improved since those times, allowing more specific descriptions. For
example only one white-tailed spider was known in 1989, the species named Lampona
cylindrata. But Norman Platnickin 2000 examined all specimens of
white-tailed spiders held in collections in Australia and overseas and was able
to separate them into 56 species of Lampona, plus 145 species in 21
other genera; an amazing 201 separate species in all. The internet, macro
lenses and digital photography have all made huge improvements in speed and
accuracy of communication and image quality, and today every good museum and
research centre now has access to a scanning electron microscope, enabling the
minutest hairs on a spider’s leg to be seen in great detail. At least some of
these minute features have taxonomic value.
Over the last few years,
the optimum tool in examining relationships between life-forms, DNA profiling,
has become more accessible. For simplicity’s sake, mitochondrial DNA of spiders
is being examined, not the whole genome. DNA analysis makes the whole process
of classification more objective because it reveals the evolutionary changes
that have led to the spider species we have today. Charts called “clades” can
be created using the data – these look and are complex, but they show clearly
the similarities, differences and relationships between spider families, genera
and species. Some spider families have been altered, divided or combined, and in
some cases new names given. This process is being used to revolutionise the
taxonomy of other life forms as well, including human ancestry.
Ron explained the origin
of and how to use his “Find-a-spider” website – on this very useful site he has
provided several ways for interested spider-hunters to identify their catches –
by family, by species name, and by photographs. Ron updates his site when a
change appears on the “World Spider Catalogue”, the High Court of Arachnology.
The Atlas of Living Australia also has links to old and new spider names. Several
questions were asked by members at the end of his talk. All showed their
appreciation of Ron and his family for travelling from Brisbane to speak to us
on such an interesting topic.
(Article and photos by Glenda Walter)
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