Lumpy

As we move inexorably towards autumn, I'm finding increasing numbers of arachnids around the garden. Many of them are tricky to identify, but this has always been regarded as one of the easiest: it's Dicranopalpus ramosus, an opilione or harvestman, which has obviously forked pedipalps, and always rests in this characteristic pose, with its legs splayed out in narrow fans to either side.

But. It seems we can't have nice things, such as easily identifiable arachnids. A few years ago some scientists wrote a paper, which sadly was well-received by opilione fanciers, in which they stated that some of the specimens people have confidently been identifying for years as Dicranopalpus ramosus are actually a separate species called Dicranopalpus caudatus, and therefore all the existing records and distribution maps are unreliable. How easy it is to tell the two species apart in the field is the subject of debate, but it seems that to be sure you need to examine them microscopically. Being possessed neither of a microscope nor of the inclination to use one, I will have to record this as Dicranopalpus ramosus agg., meaning that it's one of an aggregate of species, or Dicranopalpus ramosus s. l. (sensu lato, meaning "in the broad sense", as opposed to s. s., or sensu stricto, meaning "in the strict sense").

Taxonomists, eh? I bet they're great fun at parties.

There are two other points I'd like to make about this opilione. Firstly, the lumpy abdomen, rising to a bump at the distal end, makes this a female. Males are smaller and flatter than this, and generally darker; they sometimes have a dark stripe across the eyes, like a highwayman's mask, but they don't have this dark girdle mark around the middle. And secondly, those seemingly forked pedipalps aren't really forked at all: the apparent branch is actually an outgrowth of the palpal patella. So, as well as having a lumpy abdomen, the female D. ramosus also has knobbly knees.

I finally managed to process all Monday's Trench Wood photos today, and I've put a few highlights on my Facebook page, if you'd care to see them.