Download high resolution image here.
Timothy N. King
collected several of this apparently undescribed species of Sphaerius
with a Berlese funnel loaded with lake debris from around Highland Lake, Bount Co., AL. It is well out of range of described species. He sent me some for high-resolution imaging so that an accurate description can be made. Arnett and Thomas 2000 (Vol. 1)(1)
states, "Three nominal species are known from Texas, Arizona, California, and Washington. The genus is in need of revision." Only S. texanus
and S. politus
are listed from the US in Beutel and Raffaini 2003(2)
, though. They include an SEM ventral view of S. texanus
. Beyond that, the most complete descriptions I found of these two species are in Matthews 1899(3)
. Matthews discusses a third US species, S. scutellaris
, but that is classified as Orthoperus scutellaris
now. Perhaps that is what Arnett is referring to.
I've posted here several detailed views of three specimens each mounted and posed to best show different features. The species does not appear to be either S. texanus
or S. politus
. The most conspicuous difference is that Beutel's image of the former shows and Matthew's description of the latter states that the underside of both species is smooth. Our specimen's underside, however, is densely covered with minute irregularly shaped tubercules and pits. There are also several much larger tubercules on the terminal ventrite.
I would be happy to take and post a comparable set of images of other US Sphaerius
specimens toward the goal of the needed genus revision, if someone can send me some.
This image is from a CombineZP
processed stack of 200 images with a 2.7 µm step taken with a Mitutoyo BD Plan APO 20×/0.42 microscope objective
+ Nikon 300 mm F4 AF ED IF macro lens + Nikon D810 camera (magnification 30×; technique described here