The Black Widow guitars and basses
(some of the latter were indeed fretless, and are said to have been the first mass-produced answer to Bill Wyman's* invention, predating by a year - 1965 - the earliest fretless Ampeg bass guitars)
were marketed and branded by the Acoustic Control Corporation; some were built in the Mosrite plant, but most were made in Japan.
The designer of the instrument, Paul Barth,** also made and sold them, minus the "Black Widow" moniker, under his own marque Bartell, as well as others: Lancer, Contessa, St.George, and indeed Hohner.
Paging
@Pauly 4001, who owns
a very similar specimen.
* [Bill's bass guitar (the very first fretless electric bass guitar ever) started life as a Dallas Tuxedo, the first mass-produced bass guitar in the UK:
Dallas Tuxedo Bass - The Guitar Collection
Apparently, his was "bl--dy horrible" because of the worn frets (he'd bought it used from a friend of drummer Tony Chapman's), hence the fret removal (the rest of the mods being cosmetic):
Fretless Bass History ]
** [Barth was related to the Dopyera brothers (of DoBro and National resophonic guitars fame, as well as being the fathers of the Zorko Mini Bass, first version of the Ampeg Baby Bass electric upright).
Paul in his own right was a pivotal figure, pioneering the electric solid-body guitar along with George Beauchamp and Adolph Rickenbacker in the early 1930s: theirs was the functionally-solid electric lap steel, famously nicknamed the "Frying Pan".]