Ptolemaic army of 1st century BC

[MeinPanzer]

thank you for your replay - I would like to proceed further with some more inquiry into the tactics and equipment:

namely, did they -Ptolemaic Egyptians - use some sort of phalanx on the battlefield - I understand from reading 'Bellum Allexandrinum' that king Pharnaces of Pontus did use phalanx ( in 48 BC) against Ceasar's Domitius at Nicopolis - then it may be the case that they still used some sort of phalanx in Egypt that winter of 48/47BC?

The only evidence you will find for this would be in literary sources. Unfortunately, I am not familiar with the sources for the 1st C. BC Ptolemaic army, so I don't know the answer to that question.

also did they use some sort of a pike or shorter sarrisa? or just a Roman hasta?

Non-phalangite troops would have used regular fighting spears.

Also, from reading about the Bithynians and Galatians - via links on this forum - it seems that they traditionally found employment in the Ptolemaic army.. perhpas even taht winter 48 BC

Numerous ethnicities regularly found employment in the Ptolemaic army. The most common were Galatians, Thracians, and Greeks. I don't know all that much about Galatians in the late Ptolemaic army specifically, but I do know that Cleopatra VII had a bodyguard of Galatians.

Bithynians were less common mercenaries, but there is some evidence for them for Ptolemaic Egypt, including that of Diazelmis of Apamea, a Bithynian officer who left Bithynia to serve the Ptolemies and who was buried in Egypt in the 2nd or 1st C. BC. They were present in the later Ptolemaic army, but most likely in small numbers only.