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Specimen 1, dorsal - Sphaerius

Specimen 1, dorsal - Sphaerius
Highland Lake, Blount County, Alabama, USA
December 26, 2014
Size: 0.83 mm (sans genitalia)
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).

Images of this individual: tag all
Specimen 1, dorsal - Sphaerius Specimen 1, lateral - Sphaerius Specimen 2, ventral - Sphaerius Specimen 2, ventral close - Sphaerius Specimen 3, dorso-lateral, wings spread - Sphaerius Specimen 3, dorsal folded left wing - Sphaerius Specimen 3, lateral close (left palp missing) - Sphaerius Specimen 3, anterior (left palp missing) - Sphaerius

Tim's original image

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