Wynberg Cave, in search of harvestmen

HARVESTMEN IN WYNBERG

Team: Gonzalo Giribet, Benjamin de Bivort, Anthony Hitchcock, Peter Swart 

Observation tag: 20111105 

Acknowledgement:  All of the photographs taken on this trip were taken by Gonzalo Giribet.

Speliosiro argasiformis 

Gonzalo  Giribet and Benjamin de Bivort were visiting from Harvard University, with the intention of sampling various harvestmen (Opiliones) from around South Africa. They asked Anthony and I to accompany them to Wynberg Cave to see if we could find a specific harvestman, Speliosiro argasiformis.  This small creature had not been recorded for many years and Gonzalo was anxious to see if it was still around in order to add another data point to the geo-genetic studies he has been doing.

Just arriving at the cave entrance seemed to raise Gonzalo's spirits, as he had read so much about the cave and its invertebrate inhabitants for so long.  The question remained whether we would find his Speliosiro.

After entering the cave via what is traditionally known as the exit, Anthony made his way along the passage just below the hanging rope, to the place where we had found some harvestmen and some collembola on our previous bug hunting trip.

 HARVESTMEN

Healthy Speliosiro community.

Within minutes, Gonzalo was jumping up and down with excitement.  He had his harvestman, and it was not an isolated specimen.   Speliosiro argasiformis obviously loves the area, as there was a whole colony of them.  Males, females, adults and juveniles and in large numbers.  An obviously healthy population.  Further examination of the cave revealed them to be fairly common throughout the cave and often walking about on exposed surfaces.

Orange harvestman

A few Speliosiro, together with a larger orange harvestman were also found consuming the remains of dead fruit bats.  These were found in Pluto's Hall, almost directly below the top ladder entrance.  The orange harvestmen were also quite common throughout the cave.

White harvestman

The last harvestman of the day was a small, white, long legged Opilione which was found on the climb down from Wynberg Exit to Pluto's Hall.

Before moving to the next cave, we went looking for the tiny isopods we had found on our previous trips.  These are less than 2mm long and are possibly Protojanieria.

After all the excitement of Wynberg Cave, we made our way across to Vivarium.  The only animals of interest there were the  Speleogriphus lepidops.

INUKSHUK

Peripatopsis alba

Pseudo scorpion

For the last cave of the day, we visited Inukshuk cave.  This is one of the cave entrances in the forested valley that runs between Wynberg Cave and Hangman's Drop.  The cave is relatively shallow (close to the surface) and the entrance acts as a funnel for the forest floor debris from above.  Before entering the cave, we checked the leaf litter on the forest floor, and found a few harvestmen.

This proved to be an excellent choice to finish off the day as Gonzalo found an 8mm long pseudo scorpion and a Peripatopsis alba.  Both of these animals were approximately 4m below the surface, and very close to the twightlight zone of the cave.

These are only a few of the animals we found.  There were at least 3 other species of harvestmen that we found in the forest litter at Wynberg Cave exit and near the entrance to Inukshuk Cave.