What is the "black sphinx" in Greek magical papyrus IV?

Question

In the Greek magical papyri (Papyri Graecae Magicae or PGM), lines 2307–2314 of papyrus IV were translated into English by Hans Dieter Betz as follows:

The hair of a virgin cow, the seed of Pan
Fire from a sunbeam, colt's foot, spindle tree
Boy love, bow drill, a gray-eyed woman's body
With legs outspread, a black sphinx's / pierced vagina
All these are symbols of my power
The bond of all necessity will be
Sundered, and Helios will hide your light
At noon, and Tethys will o'erflow the world

_{Hans Dieter Betz (1986). The Greek Magical Papyri in Translation, Including the Demotic Spells, p. 80. University of Chicago Press.}

_{A digitized version of papyrus IV is available via the Bibliotheque nationale de France.}

What is puzzling to me is that nearly all the contents of this passage are easily identifiable: Helios, Tethys, Pan (seed of Pan seems to be parlance for some kind of herb, if other PGM texts are of use here). Yet, what stands out as not being easily identifiable is the "black sphinx." I have not encountered it elsewhere in Greek or near-eastern mythology. Of course there is a sphinx in Oedipus, however it is does not take on any epithet that's similar to "black sphinx".

I've also tried googling around the term "black sphinx" but little-to-nothing comes up. This does not surprise me because it's a very specialist kind of field. Many of the texts that classicists study are not indexed well by search engines.

From my own musings, if it's anything at all, then either "black" was included for a reason, but the motivation is unknown to me. Or, it may be that "black sphinx" is an entity unto itself.

Question

Assuming "black sphinx" was included with some kind of intent (not just a throwaway predicate), what, if anything, may we refer to elsewhere in the literary/mythological world of the ancient Greeks to help us make sense of the allusion to a "black sphinx."?

Online version

Not for the faint of heart: https://kosmossociety.chs.harvard.edu/wp-content/uploads/2019/04/CHS-Greek-Magical-Papyri-Examples.pdf

Answer 1

The word σφίγξ was used not only for the mythological Sphinx, but also for a kind of monkey or ape. This animal is mentioned in a few ancient authors, but not with enough detail to identify the species with any certainty:

These are also sphinxes in both the Trogodyte† country and Ethiopia, and in shape they are not unlike those depicted in art save that they are more shaggy of hair, and since they have dispositions that are gentle and rather inclined towards cunning they yield also to systematic training.

_{Agatharchides of Cnidus (2nd century BCE). On the Erythraean Sea. In Diodorus of Sicily (1st century BCE). Bibliotheca historica 3.35. Translated by C. H. Oldfather (1835). Diodorus of Sicily, volume II, p. 181. London: William Heinemann.}

_{† The Trogodytes or Troglodytes (“cave-dwellers”) seem to have been a people living near the Red Sea coast of Africa.}

Æthiopia produces the lynx in abundance, and the sphinx, which has brown hair and two mammæ on the breast, as well as many monstrous kinds of a similar nature

_{Pliny the Elder (1st century CE). Natural History 8.30. Translated by John Bostock (1855). Perseus Digital Library.}

In our country also there are intelligent animals, but they are few and not so numerous as in India. In that land, for example, are the Elephant, the Parrot, the Sphinx-ape, and the Satyrs as they are-called.

_{Claudius Aelianus (3rd century CE). On the Characteristics of Animals 16.15. Translated by A. F. Scholfield (1959). Aelian on the Characteristics of Animals, volume 3, p. 277. London: William Heinemann.}

Clearly not all these descriptions can refer to the same species of animal, as there are no monkeys common to Africa and India, so it seems that the word was used generally for several kinds of primate.

The Nile mosaic of Palestrina (2nd–1st century BCE) depicts the fauna of Nubia (modern southern Egypt and Sudan) and includes two monkeys labelled ϹΦΙΝΓΙΑ (sphinxes).

(See this answer on history.stackexchange.com for more about the mosaic and its fauna.)

So under this interpretation the “black sphinx” of the spell was some kind of black monkey or ape. Several kinds of animal are mentioned in this part of the spell (lion 2303, she-wolf 2303, turtledove 2306, camel 2306, cow 2307) so “sphinx” meaning “monkey” is consistent with the context.