The genera Theridion and Achaearanea have historically been something of a catch-all for small Theridiid spiders. They may be found to belong to different genera and even if the genus is actually identified, they are often impossible to get to species level because they are so small, many are undescribed and convincing identification would require close inspection of both the mature male and mature female genitals with a microscope.
There seems to be a tendency to put unsclerotized spiders of the Theridion/ Achaearanea type with a conventional looking (non-turreted) cephalothorax and a globular (not pointy or peaked) abdomen into Theridion; while similar spiders with a high and pointy peak tend to be labelled Achaearanea. This morphological (body shape) distinction may not be supported in all cases.
There is also very likely to be a great deal of variation within a species which leads in the short term more and more described species in the published literature. Careful inspection, observation and experiments may eventually resolve these to fewer species.
Until we have some reliable macro-morphological keys (species identification by characteristics that can be discerned by the naked eye, or a hand lens) amateur naturalists will find it difficult to pin down exactly what species their spider is, and often even what genus it belongs to.
On this page there are a number of small Theridiids that have been grouped by individual appearance, loosely labelled in genera that seem most appropriate. It should be noted this identification is provisional.
- Achaearanea sp. Pale speckled juvenile from above
- Achaearanea sp. Pale speckled juvenile from above side view
- Achaearanea sp. Pale speckled from side
- Achaearanea sp. Pale speckled from behind
- Theridion type, charcoal with double white stripe, male from above
- Theridion type, charcoal with double white stripe, male from side
- Theridion type, charcoal with double white stripe, male facing
- Theridion type, charcoal with double white stripe, male undersides
- Theridion type, charcoal with double white stripe, from above, oblique
- Male subadult with huge palps
- Male subadult with huge palps
- Theridion sp Tiny, rotund, boldly patterned, from above
- Theridion sp Tiny, rotund, boldly patterned, from side
- Theridion sp Tiny, rotund, boldly patterned, from below
- Theridion sp Tiny, rotund, boldly patterned, from above
- Theridion sp Tiny, rotund, boldly patterned, from below
- Theridion theridioides? ex Tobesoa from side
- Theridion theridioides? ex Tobesoa female with egg sac from above
- Theridion theridioides? ex Tobesoa from side
- Theridion theridioides? ex Tobesoa from front upside down
- Theridion type, speckled, from above
- Theridion type, speckled, from above
- Theridion 'long-thighs' male from above
- Theridion 'long-thighs' female from above
- Theridion 'long-thighs' female from below
- Theridion type side on
- Theridion type from above
- Female with detritus nest
- Female with detritus nest
- Female with detritus nest, epigynum
Achaearanea sp. Pale speckled juvenile from above
This small Theridiid about 3mm body length is likely a juvenile, yet still demonstrating some interesting speckles.
Achaearanea sp. Pale speckled juvenile from above side view
Achaearanea sp. Pale speckled from side
Achaearanea sp. Pale speckled from behind
Theridion type, charcoal with double white stripe, male from above
A Theridiid body length about 1mm. Quite distinctive abdominal markings but this may not mean a lot. Large palps on this sub-adult male.
Theridion type, charcoal with double white stripe, male from side
Theridion type, charcoal with double white stripe, male facing
Theridion type, charcoal with double white stripe, male undersides
Theridion type, charcoal with double white stripe, from above, oblique
Male subadult with huge palps
Male subadult with huge palps
Theridion sp Tiny, rotund, boldly patterned, from above
This small Theridiid, somehat like but not Achaearanea veruculata, had a body length 1mm.
Theridion sp Tiny, rotund, boldly patterned, from side
This small Theridiid, somehat like but not Achaearanea veruculata, body length 1mm.
Theridion sp Tiny, rotund, boldly patterned, from below
Theridion sp Tiny, rotund, boldly patterned, from above
Theridion sp Tiny, rotund, boldly patterned, from below
Theridion theridioides? ex Tobesoa from side
A tiny Theridiid, body length abount 1mm possibly Theridion (Tobesoa) theridioides which is found more to the north, but hard to tell given that many small Theridiids in the Greater Brisbane area remain undescribed. Dr Robert Raven, QM, advised us of this possibility of this identification, which would require confirmation in the lab.
Theridion theridioides? ex Tobesoa female with egg sac from above
Theridion theridioides? ex Tobesoa from above
Another specimen body length 1.5mm
Theridion theridioides? ex Tobesoa from side
Female, body length 2mm from side.
Theridion theridioides? ex Tobesoa from front upside down
Female, body length 2mm
Theridion type, speckled, from above
A not uncommon undescribed Theridiid spider body length about 4mm large abdomen small cephalothorax. Body length about 2.5 mm.
Theridion type, speckled, from above
Theridion 'long-thighs' male from above
These small Theridiids, the male and female upper and lower, recognisable to family by the tarsal comb on leg 4, were together in a minimal loose tangled web on the middle-upper leaves of a young Alectryon tomentosus. Quite common. For the moment, can probably only be referred to by the generic name Theridion.They somewhat resemble Theridion pyramidale.
Theridion 'long-thighs' female from above
Theridion 'long-thighs' female from below
Theridion type side on
Theridion type from above
Female with detritus nest
Female with detritus nest
Female with detritus nest, epigynum
