A giant phacopid, Pedinopariops (Hypsipariops) vagabundus, is not a "real" Drotops, although often mislabeled as a "Drotops", due to the similar size and appearance. A similar feature of Hypsiopariops, Drotops (and Eldredgeops) is also the eye, with the lenses surrounded by the so-called sclera (ridges), however Drotops's eye is structured a little different and more ornamented. And there's more differences - the most obvious: conical-pointy shaped tuberculation on the glabella, tubercules shaped like tiny spines on the thorax, librigenia and pygidium (on a Drotops) vs. rounded tuberculation and smooth thorax, librigenia and pygidium covered with pores (on a Hypsi). No need to point out the difference in preparation I guess. These structures are often erased in commercial preparation (especialy the tuberculation on Drotops) and so the difference between a Drotops and a Hypsiopariops commercially a little blured...
Since this Hypsipariops was recently prepared for trilobiti.com, instead of a prep-sequence post, I've decided to illustrate the difference between a real Drotops (D. megalomanicus megalomanicus) and a Hypsipariops. Often mislabeled because the name Drotops is well known. Moroccans have to work several days to find a single good giant phacopsid, a good Pedinopariops (Hypsipariops) is just as rare as a good Drotops, if not rarer.
Close up of pygidium, thorax and cephalon, with clearly visible pores:
Closeup of a Drotops megalomanicus megalomanicus, coated white to clearly see totally different ornamentation:
Hypsipariops:
Easy to tell the difference, right?