daughter of Ptolemy XII
sister of Cleopatra VII

Prompted by her tutor, the youngest child of Ptolemy XII briefly claimed the throne of Egypt in 48 BCE & laid siege to Alexandria cutting off its water supply as Julius Caesar restored her older sister. Reinforced by the 7th legion, Caesar broke the Egyptian siege & took Arsinoë captive (Jan 47 BCE). After displaying her in his triumphal parade in Rome Caesar allowed her sanctuary in the temple of Artemis at Ephesus. Years later, with Caesar dead, Cleopatra prevailed upon Mark Antony to have her murdered.*

References: Caesar, Alexandrian War 4.
                   Cassius Dio, Roman History 42.39-40; 43.19; 48.24.*
                   Appian, Civil Wars 5.9.
                   Josephus, Antiquities 15.89; Contra Apion 2.57.

* Cassius Dio mistakenly claims Cleopatra had Antony kill her brothers rather than her sister.                

Other resources on line:

• Arsinoë IV  - Christopher Bennett's annotated Egyptian Royal Genealogy provides detailed references & sources.

• Arsinoë IV - Jona Lendering lists biographical data & key dates [Livius: Articles in Ancient History].

• Arsinoë IV of Egypt - notated article in Wikipedia's web.