The Stridulating Organ of an Ornithoctoninae.

Using the stridulatory organ of Ornithoctonus aureotibialis von Wirth & Striffler 2005 as an example, we show the structural design of this taxonomically important structure! It's not a simple structure but it consist of different parts, characterized by different Types of feathered Setae (= Scopula) arranged on different parts of the particular Segment.

On Chelicerae outside (= retrolateral) you can often find the following structures:

TYPE 1 consist of soft Scopula hairs. The fine hairs are arranged completely around the stem hair.

TYPE 2 & 3 consist of strong bristles in which the fine hairs are only arranged on one Side of the stem Setae, whereas Type 2 bristle is clearly stronger than Type 3.

TYPE 4 consist of very strong and stout bristles which are shaped sword like and in which the fine hairs are only arranged on the edges of the "Sword".

On the opposite Side, on Coxa and Trochanter of Palp, you can see the Setae Structures which rub against the mentioned structures of the Chelicerae retrolateral. During the Stridulating process, the strong Spines below the Sutur on Palpcoxa innerside ( = prolateral) rub against Type 4 bristles. The feathered Setae above the Sutur rub against Type 1 hairs whereas the Spines above the Sutur rub against the Type 3 bristles. Last but not least the strong feathered hairs of Palp Trochanter prolateral rub against the Type 2 bristles.

As you can see, Stridulating Organs in Asian Theraphosid Spiders like the Ornithoctoninae are not simple structures. They are very complicated and their structure is very useful for phylogenetic and taxonomical Work (Paper in prep.).