Laudator Temporis Acti

A.J. Woodman, The Annals of Tacitus, Book 4. Edited with a Commentary (Cambridge: Cambridge University Press, 2018 = Cambridge Classical Texts and Commentaries, 58), p. 330, n. 140 (on 4.73.1 soluto iam castelli obsidio et ad sua tutanda degressis rebellibus):

It was observed in the earlier nineteenth century that, in a passage indebted to his predecessor Marinus, the geographer Ptolemy lists side by side two places in Germany called Φληούμ and Σιατουτάνδα (Geog. 2.11.12), of which the latter looks suspiciously like a misguided transliteration of T.'s sua tutanda; for discussion see Norden 284-6.

For Φληούμ see Tacitus, Annals 4.72.3 (Olennius infensos fuga praevenit, receptus castello cui nomen Flevum).

Woodman refers to Eduard Norden, Die germanische Urgeschichte in Tacitus Germania, 4th ed. (Darmstadt: Wissenschaftliche Buchgesellschaft, 1959).

Woodman's translation of Tacitus, Annals 4.72.2-4.73.1:

Olennius forestalled their ferocity by flight, being received at a stronghold whose name is Flevum, where a by no means contemptible unit of citizens and allies presided the Ocean's shores.

When all this became known to L. Apronius, the propraetor of Lower Germany, he summoned detachments of the legions from the upper province and chosen men of the auxiliary infantry and cavalry, and, sailing each army down the Rhine, brought them simultaneously against the Frisians—the blockade of the stronghold having already been raised and the rebels withdrawn to protect their own property [ad sua tutanda].

Olennius infensos fuga praevenit receptus castello cui nomen Flevum; et haud spernenda illic civium sociorumque manus litora Oceani praesidebat.

Quod ubi L. Apronio inferioris Germaniae pro praetore cognitum, vexilla legionum e superiore provincia peditumque et equitum auxiliarium delectos accivit ac simul utrumque exercitum Rheno devectum Frisiis intulit, soluto iam castelli obsidio et ad sua tutanda degressis rebellibus.

I don't like "presided" as a rendering of "praesidebat"—I prefer "guarded" (Michael Grant's translation).

Ptolemy, Geography 2.11.12 (tr. Edward Luther Stevenson):

The towns located in Germania in the northern clima are

Phleum      28 45    54 45
Siatuanda      29 20    54 20

πόλεις δὲ τίθενται κατὰ τὴν Γερμανίαν ἐν μὲν τῷ ἀρκτικῳ κλίματι αἵδε·

Φληούμ      κηʹ ∟ʹʹδʹʹ    νδʹ ∟ʹʹδʹʹ
Σιατουτάνδα      κθʹ γʹʹ    νδʹ γʹʹ