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Strange spider sightings
Invertebrata 8, June 1997

Recent months have seen two rather strange phenomena in the spider world in Tasmania.

For most of this year, a property at Richmond in the south of Tasmania has had a massive spider infestation of a large heap of wood mulch. Although initially representing a mystery, the countless numbers of spiders were eventually identified by Dr Rob Raven of the Queensland Museum as Ostearius melanopygius, the midget spider, in the family Linyphiidae.

The spiders have woven dense mats of silk all over the mulch heap. Attempts by the property owner to rake the mats off are useless as they reappear the next morning. Dr Raven suggests that lack of wind may have caused the young spiders to be unable to disperse by ballooning, leaving them to continually make mats so dense that the webs become too heavy to blow away even under windy conditions.

O. melanopygius is widespread, mainly in cool temperate parts of the world. It has not been officially recorded in Tasmania before, although it has been found in a cave near Hamilton in Victoria. It is also found in Europe, Japan, in an ants' nest in Brazil, and on mountain tops in Hawaii and East Africa. A fascinating aspect of this spider's biology is that it occurs in such isolated populations on different continents.

A second silky phenomenon appeared beside the Tinderbox Road, also in southern Tasmania, and was spotted from a moving car. This remarkable feat of vision was possible because the roadside bank was covered in webs that had caught the late autumn dew. Without this dew the webs would have been barely visible even from a metre away.

Closer inspection revealed the bank was covered with tiers of platform-like webs, ranging from saucer-sized to the diameter of a twenty-cent coin. The bank resembled an expensive holiday resort where the rooms are layered in tiers, each room having its own uncovered balcony.

Enthusiastic digging (to the fascination of passing motorists) revealed one male spider, three females and two egg sacs. The palps on the male are extremely complex in structure. The spiders have been identified as Corasoides, platform spiders, but the species is still undetermined. Species in the genus Corasoides are found across southern Australia and Tasmania.

Each platform web consists of a flat sheet with guy-ropes extending from the sides to keep it rigid. The end nearest the bank narrows into a funnel which leads into a burrow in the ground. A labyrinth of silk threads above the platform deflects flying insects onto the sheet, where they can be seized by the spider.

During autumn and winter large numbers of platform webs can be seen, but by spring and early summer numbers are greatly reduced. The spiders mature in late spring. Eggs are laid in cocoons in the summer and remain in the females' burrows until the spiderlings emerge the following spring. Egg cocoons may be confused with pebbles or rabbit droppings due to the female's habit of covering the cocoon with a layer of dust.

We returned to the Tinderbox bank a week later. Despite similar conditions and time of day, only one or two tiny webs could be seen, and no sign of any burrows. Presumably the spiders were still in the bank. They may have destroyed their webs and sealed off the burrow entrances during a change of weather that week.

We would be interested to hear of any other sightings of unusual webs.

Liz Turner and Jeff Cossum
Tasmanian Museum & Art Gallery
GPO Box 1164M
Hobart TAS 7001

How to collect and preserve land snails
Invertebrata 8, June 1997

Collecting. Land snails are best found in their hiding places in dark, damp situations, such as under logs or rocks, or in leaf litter. With the help of a torch you can find them crawling about at night, but this is a far less reliable method. Collect specimens into containers with well-fitting lids. If you need to keep the snails for long periods before processing, put DEAD leaves or dampened tissues or paper towelling in the container. DON'T use live, green vegetation as this is still alive and respiring. Try to put only one species of snail in each container as some species are carnivorous and will eat other snails. (See the references below to learn which snails are carnivorous.)

Labelling. All specimens must be labelled at the time of collecting. One method is to use a field numbering system, in which you simply number the containers and write down the relevant habitat notes and collecting data in a notebook. A drawback of this method is that the loss of a notebook can render a whole collection useless for research purposes. Write the field number and the date in dark (soft) pencil on a piece of tough paper and put this label INTO THE CONTAINER with the specimen. Labels stuck on the outside of containers can fall off, and ink writing can dissolve off the label if the label is transferred to alcohol.

For permanent labelling, the information which should go with each lot of specimens is:

• name of collector
• date of collection
• locality and map grid reference, or details of the exact place the specimen was found
• habitat in which the specimen was living
• other interesting information (e.g., 'snail was eating earthworm').

Without the first three items on this list the specimens will be of little or no use for research purposes. Locality information is particularly important; it should be possible for someone else to go back to the collecting site from your description of the place.

Preserving and fixing. Dead shells are of some use but live-collected specimens, with the animal properly preserved, are far more useful.

Dead shells can be washed in warm tap water, air-dried and put in a clean, dry container with a label. Live specimens should be relaxed and fixed. Place the live snails in a clean container with two or three small crystals of menthol (you can get small quantities of menthol crystals from a chemist). Fill the container with cold tap water to the very top, cap the container to exclude air and leave overnight. Make sure that no more than a third of the space in the container is taken up by specimens. Next day, pour off the water and fill the container with 75% alcohol. The snails should have relaxed and become extended in the menthol-saturated water, and should remain extended when fixed in the alcohol.

Packaging and shipping. Live specimens should never be packed with GREEN vegetation as this will kill the snails in a closed container within a few days. Put live specimens in a container with DEAD leaves or moist paper towelling. Leave plenty of room for the snails: they should take up no more than 5% of the volume of the container. Secure the lid very firmly. It's a good idea to have labels both inside and outside the containers, as snails may eat labels if left a long time. Preserved specimens can be sent in a small container with the liquid alcohol replaced by tissue dampened with alcohol, but the container must be securely sealed to prevent the alcohol from evaporating away.

For secure shipment through the post, put the containers inside a bigger container, then put this bigger container in a box and surround it with packing material.

Live or preserved snails, properly labelled and packed as described, can be sent for identification to the author c/- Queen Victoria Museum and Art Gallery, Wellington Street, Launceston TAS 7250.

Dr Brian J. Smith

More information:

Kershaw, R.C. 1991. Snails and Slug Pests of Tasmania. Launceston: Queen Victoria Museum and Art Gallery; 67 pp.

Smith, B.J. and Kershaw, R.C. 1981. Tasmanian Land and Freshwater Molluscs. Fauna of Tasmania Handbook No. 5. Hobart: Fauna of Tasmania Committee, University of Tasmania; 148 pp.

Towards nationally consistent identification of larval caddisflies
Invertebrata 8, June 1997

The problem. Identification of the immature stages of aquatic insects to known species is often not possible, as anyone working with Australian freshwater macroinvertebrates will know. Keys to caddisfly larvae are not available for many families, in part because of the large number of undescribed species and in part because larval stages of described species have not always been associated with adults .

Working voucher collections are often established by individual organisations to assist with identification. Each of these voucher collections has its own coding system for unnamed taxa, making it impossible to equate identifications based on different voucher collections.

The solution. Keys to Australian larvae of the caddisfly families Conoesucidae, Calocidae and Helicophidae are being prepared by the author with funding from the Monitoring River Health Initiative (MRHI).

These families occur in eastern Australia, New Zealand and southern South America (Helicophidae only). Conoesucidae are widespread and common in streams in eastern Australia. The Calocidae and Helicophidae are apparently less common, with several larval taxa represented by very few specimens. Some calocids and helicophids occupy unusual habitats such as small seeps and even terrestrial leaf litter, in Tasmania at least. Similar work on other aquatic taxa is being done by John Dean and Ros St Clair at the Victorian EPA, David Cartwright at Melbourne Water (Werribee) and Phil Suter at LaTrobe University (Albury-Wodonga).

The MRHI project in Tasmania involves:

• Examination of collections of larval Trichoptera and definition of genus- and species-level taxa.
• Development of illustrated keys to families, genera and species. A standardised coding system will be used for unnamed taxa.
• Examination of the major working voucher collections to ensure that the same taxon in different collections is recognised by its correct name or unique code.
• Establishment of a national voucher collection at the Museum of Victoria.
• Development of a character state database for input to computer-based keys.
• Preparation of a database of collection data for the specimens examined.

The work is due to be finished in August 1997. Keys will be published and presented at a taxonomy workshop in February 1998 at the Murray-Darling Freshwater Research Centre, Albury.

Dr J.E. Jackson
Zoology Department
University of Tasmania
GPO Box 252-05
Hobart TAS 7001

Girault's gems
Invertebrata 8, June 1997

Alexandre Arsène Girault (1884-1941) was an American-born entomologist who spent much of his working life in Queensland. He published a large number of 'straight' papers on Australian chalcidoid Hymenoptera. Below is a list of some papers which Girault published privately, perhaps because they were turned down by respectable journals! Delight in his imaginative titles...

1921 New animals of Australia and the old men of the earth.

1922 The true remedy for head lice. Dedication of a new animal to the quality of majesty and so forth.

1923 Loves wooed and won in Australia; Microscopitis, womanitis and new Hexapoda.

1924 Lese majeste, new Insecta and robbery.

1925 Indications (in new insects) of ruling power and law in nature; An essay on when a fly is lovable, the ceremony of baptizing some and unlovely hate; Some gem-like or marvellous inhabitants of the woodlands heretofore unknown and by most never seen or dreamt of; New Queensland Insecta captured without any reference to use.

1926 Characteristics of new Australian insects. (Refused publication on pretext).

1927 New Australian animals so far overlooked by outsiders.

1928 A prodigeous [sic] discourse on wild animals; Some new hexapods stolen from authority; Some Insecta and a new all highness. (Notes compiled in fear and sorrow.); Notice of a curious professor and of native wasps and wood lice.

1929 Description of a case of lunacy in Homo and of new six-legged articulates.

1933 Some beauties inhabitant not of commercial boudoirs but of nature's bosom, notably new insects.

1934 New Capsidae and Hymenoptera, with note on an unmentionable.

1936 Terror-errors; and novitates of Pterygota (or earth realities not state bound.)

1937 New naturals, unorthodoxies and non-pollutions, viz. new hexapods.

Trevor Semmens
Department of Primary Industry and Fisheries
St Johns Avenue
New Town TAS 7008

Weird geology
Invertebrata 8, June 1997

Where was Australia in the Paleozoic, before all the world's land masses combined as Pangea?

Conventional reconstructions show Australia (as part of Gondwana) migrating from just north of the Equator in the Cambrian to ca. 70º south by the end of the Permian Period. The 'leading edge' of our portion of Gondwana was Australia's east coast. A recent paper (Dobson 1996) suggests that during this time the 'leading edge' collided with the east coast of North America, pushing up the mountain range now known as the Appalachians.

This unorthodox view is supported by a particularly good fit between the pre-Cretaceous rocks of eastern North America and southeastern Australia, with Australia turned 'north to south'. In this position, Tasmania lies opposite eastern Canada. (Did Tasmanian Premier Tony Rundle know this when he suggested this autumn that Tasmania should model its economy after that of the Canadian province of New Brunswick?)

Dobson's paper inspired me to re-read some references about centipedes. Nowadays the centipede order Craterostigmomorpha is represented by one (or possibly two) species living in Tasmania and the South Island of New Zealand. However, a beautifully preserved centipede fossil (organic remains, not mineralised) from the mid-Devonian in New York State is remarkably similar to modern Craterostigmus tasmanianus, and was first thought to be a craterostigmomorph. After further study, the American expert Dr William Shear erected a new order, Devonobiomorpha, for this fossil species, Devonobius delta (Shear and Bonamo 1988). Dr Hendrik Borucki, a German zoologist, has disagreed and prefers to see Devonobius as a craterostigmomorph (Borucki 1996). Shear (pers. comm.) has meanwhile examined more Devonobius fossils and is confident that Devonobiomorpha and Craterostigmomorpha are distinct taxa.

What's clear is that something resembling the ancestor of our Craterostigmus was living in eastern North America about 380 million years ago. If the new geological theory finds additional support, we can start wondering whether Devonobius walked to Australia/New Zealand during the postulated mid- to late Paleozoic collision. Or maybe Devonobius was an Australian gift to the Yanks?

Bob Mesibov
QVMAG

References:

Borucki, H. 1996. Evolution und phylogenetisches System der Chilopoda (Mandibulata, Tracheata). Verh. naturwiss. Ver. Hamburg 35: 95-226.

Dobson, J.E. 1996. A palaeogeographic link brtween Australia and eastern North America: a New England connection? J. Biogeography 23: 609-617.

Shear, W.A. and Bonamo, P.M. 1988. Devonobiomorpha, a new order of centipeds (Chilopoda) from the Middle Devonian of Gilboa, New York State, USA, and the phylogeny of centiped orders. Am. Mus. Novitates 2927: 1-30.

Historical footnote
Invertebrata 8, June 1997

The first major publication in Tasmanian botany was Robert Brown's Prodromus Florae Novae Hollandiae et Insulae Van Diemen (1810). Brown arrived in Tasmania in 1803 and collected, by his own estimate, some 700 species of Tasmanian plants while he was here.

It's a little-known fact that Brown was also supposed to collect insects. The young Scot had been invited by Sir Joseph Banks to serve as naturalist on HMS Investigator, commanded by Matthew Flinders, on a scientific expedition to 'New Holland'. Brown was told to concentrate on botany, entomology and ornithology during his stay in Australia. Somehow or other the insects got neglected. Writing to Banks from Port Jackson in 1802, Brown apologised as follows:

In zoology I have done but little...the collecting, preserving and description of plants preventing me from paying half the attention to the animal kingdom which its great importance deserves...(quoted in Edwards 1981, p. 146).

During his nine-month stay in Tasmania, Brown lived and worked on the Lady Nelson at Port Dalrymple and joined the settlements at Risdon Cove and Sullivan's Cove on the Derwent. He climbed Mt Wellington ten times and catalogued 540 plant species from the mountain. But no insects...

Bob Mesibov (Ed.)

Reference:

Edwards, P. (1981) Botany of the Flinders voyage. In Carr, D.J. and Carr, S.G.M. (eds.), People and Plants in Australia, pp. 139-166. Sydney: Academic Press.

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