by Joseph DeSisto
I feel like I’m on a roll with the whole common-name-inventing thing, so I’m going to have a go at another millipede family: the Haplodesmidae. These millipedes are poorly known, largely because they are often tiny and cave-dwelling. Beneath the microscope, however, they become utterly captivating. The haplodesmids have intricately shaped and textured exoskeletons, appearing almost as if they were crafted by an artist with very tiny instruments. For the purposes of this blog they will be called the “sculptured millipedes.”
The millipede above has curled into a protective spiral, with its head at the center. The species name asteroides means “star-like” and refers to the shape formed when it spirals.
Here’s another, Eutrichodesmus incisus, newly described in Golovatch et al. (2009a) from remote Chinese caverns:
Notice the way the back plates, or tergites, have bumps and sutures like the surface of a basketball. They even look a little fuzzy, but it isn’t fuzz — each one of those tergites is covered in microscopic spines. Here’s a close look at the junction between a tergite and a prozonite (the part of a segment that goes before/under the tergite).
The tergite and prozonite have very different textures! Not only is the tergite bumpy, each bump is covered in tiny, finger-like projections or microvilli:
The prozonite, meanwhile, is covered in tiny spines. If we look even closer we can see that these spines even come in two different shapes, neatly arranged in rows like a shark’s teeth:
Pretty cool, right? At this point you’re probably wondering why sculptured millipedes look so weird, but I haven’t even shown you the weirdest one. The most bizarre-looking haplodesmid is star-shaped like E. asteroides, but even more so. Also like asteroides, it was only just described in 2009, from a series of Vietnamese caves (Gorovatch et al. 2009b).
Back to the obvious question: why are sculptured millipedes so sculptured? It’s an interesting question, but unfortunately not too much attention has been paid to the minute details of these already minute millipedes. In addition to being tiny, sculptured millipedes are also almost always found in caves, which are often remote and difficult to explore.
So, no one really knows why aster is star-shaped, or why incisus has tiny shark-teeth on its body. If I had to guess I would say that aster‘s projections make the millipedes more difficult to swallow, which is one of the reasons millipedes form spirals in the first place.
As for the teeth on the prozonites — I really haven’t got a clue.
The sculptured millipedes, like many invertebrate families, were barely known until a few intrepid taxonomists got to work on documenting the species. Now that this is starting to happen, perhaps we will find out what their strange projections/ridges/teeth/villi are for. I’m betting we will, and I certainly hope so — whatever reason there is, I’m sure it’s amazing.
Golovatch S.I., J. Geoffroy, J. Mauries, and D. VandenSpiegel. 2009a. Review of the millipede family Haplodesmidae Cook, 1895, with descriptions of some new or poorly-known species (Diplopoda, Polydesmida). ZooKeys 7: 1-53
Golovatch S.I., J. Geoffroy, J. Mauries, and D. VandenSpiegel. 2009b. Review of the millipede genus Eutrichodesmus Silvestri, 1910 (Diplopoda, Polydesmida, Haplodesmidae) with descriptions of new species. ZooKeys 12: 1-46.