The coins of Pecennius Niger, the eastern challenger to the Roman throne in AD 193, exhibit three characteristics, rarity, desirability and ugliness. One of my two examples, illustrated above certainly exhibits the latter characteristic (my other example being much worse). These features were used by Oliver Wendell Holmes in his 1872 work The Poet at the Breakfast Table which features a conversation with an entomologist:
"What a superb butterfly you have in that case! -
-O, yes, yes, well enough. These Lepidoptera are for children to play with. Give me a Coleoptera, and the kings of the Coleoptera are the beetles! -
The particular beetle he showed me was an odious black wretch that one would kick out of his path, if he did not serve him worse than that. But he looked at it as a coin collector would look at a Pescennius Niger.
-A beauty!-he exclaimed, -and the only specimen of the kind in this country, to the best of my belief. A unique, sir, and there is pleasure in exclusive posession. Not another beetle like that short of South America, sir -"
Whilst I cannot claim unique I was pleased to acquire this specimen, it being a variety not fully as the description in RIC, the closest attribution I can give is cf 23-5.
My wretched second specimen, below, is RIC 5.