The line in the Dialogue
of Justin Martyr about Damascus now belonging to Syrophoenicia looks like it could easily be a gloss: not the sneaky kind of gloss that aims at subtly shifting the underlying theology or whatnot, but rather an explanatory gloss meant to clarify or update information.
Here is a good example of an explanatory gloss:
Josephus, Antiquities 20.10.5 §247: 247 Herod was then made king by the Romans, but did no longer appoint High Priests out of the family of Asamoneus; but made certain men to be so that were of no eminent families, but barely of those that were priests, excepting that he gave that dignity to Aristobulus. For when he had made this Aristobulus, the grandson of that Hyrcanus who was then taken by the Parthians, and had taken his sister Mariarmne to wife, he thereby aimed to win the goodwill of the people, who had a kind remembrance of Hyrcanus. / 247 τὴν δὲ βασιλείαν Ἡρώδης παρὰ Ῥωμαίων ἐγχειρισθεὶς οὐκέτι τοὺς ἐκ τοῦ Ἀσαμωναίου γένους καθίστησιν ἀρχιερεῖς, ἀλλά τισιν ἀσήμοις καὶ μόνον ἐξ ἱερέων οὖσιν πλὴν ἑνὸς Ἀριστοβούλου τὴν τιμὴν ἀπένεμεν. 248 τὸν δ᾽ Ἀριστόβουλον Ὑρκανοῦ τοῦ ὑπὸ Πάρθων ληφθέντος υἱωνὸν ὄντα καταστήσας ἀρχιερέα τῇ ἀδελφῇ αὐτοῦ συνῴκησεν Μαριάμμῃ, τὴν τοῦ πλήθους πρὸς ἑαυτὸν θηρώμενος εὔνοιαν διὰ τὴν Ὑρκανοῦ μνήμην. εἶτα φοβηθείς, μὴ πρὸς τὸν Ἀριστόβουλον πάντες ἀποκλίνωσιν, ἀνεῖλεν αὐτὸν ἐν Ἱεριχοῖ πνιγῆναι μηχανησάμενος κολυμβῶντα, καθὼς ἤδη δεδηλώκαμεν.
Eusebius, Demonstration 8.2.93: 93 Josephus, himself a Hebrew, is sufficient evidence of this, giving the history of those times in the eighteenth book of the Archaeology of the Jews: “Herod was then made king by the Romans, but did no longer appoint High Priests out of the family of Asamonaeus (and these were called Maccabeans), but made certain men to be so that were of no eminent families, but only of the Hebrew race, excepting that he gave that dignity to Aristobulus. For he made this Aristobulus, the son of Hyrcanus, high priest, and took his sister Mariamne to wife, aiming at winning the goodwill of the people, who had a kind remembrance of Hyrcanus.” / 93 μάρτυς ἀξιόχρεως τούτων ὁ ἐξ αὐτῶν Ἑβραίων Ἰώσηπος, ὧδέ πως ἱστορῶν τὰ κατὰ τοὺς χρόνους ἐν ὀκτωκαιδεκάτῳ τῆς Ἰουδαϊκῆς Ἀρχαιολογίας· «τὴν δὲ βασιλείαν Ἡρώδης παρὰ Ῥωμαίων ἐγχειρισθεὶς οὐκέτι τοὺς ἐκ τοῦ Ἀσαμωναίου γένους» (οὗτοι δὲ ἦσαν οἱ καλούμενοι Μακκαβαῖοι) «καθίστησιν ἀρχιερεῖς, ἀλλά τινας ἀσήμους καὶ μόνον ἐξ ἱερέων ὄντας, πλὴν ἑνὸς Ἀριστοβούλου, ὃν Ὑρκανοῦ υἱὸν ὄντα καταστήσας ἀρχιερέα, τῇ ἀδελφῇ αὐτοῦ συνῴκησε Μαριάμμῃ, τὴν τοῦ πλήθους πρὸς αὐτὸν θηρώμενος εὔνοιαν διὰ τὴν Ὑρκανοῦ μνήμην.»
The ancients had not yet invented brackets, footnotes, or endnotes, so inserting an explanation of something that the reader might find confusing or obscure was a fairly common thing to do. Another way such glosses could enter the stream of textual transmission is from the margin; but margins could also
be used for readings which had accidentally been omitted, so a later scribe might move what began as a marginal explanation into the text, supposing himself to be restoring the original.
The text in Justin bears every mark, to my eye, of potentially being such a gloss:
Justin Martyr, Dialogue 78.10: 10 Moreover, that sinful and unjust power is termed well in parable, Samaria. And none of you can deny that Damascus was, and is, in the region of Arabia (although now it belongs to what is called Syrophoenicia). Hence it would be becoming for you, O men, to learn what you have not perceived, from those who have received grace from God, namely, from us Christians; and not to strive in every way to maintain your own doctrines, dishonoring those of God. / 10 ἁμαρτωλὸν δὲ καὶ ἄδικον οὖσαν ἐν παραβολῇ τὴν δύναμιν ἐκείνην καλῶς Σαμαρείαν καλεῖ. ὅτι δὲ Δαμασκὸς τῆς Ἀρραβικῆς γῆς ἦν καὶ ἔστιν (εἰ καὶ νῦν προσνενέμηται τῇ Συροφοινίκῃ λεγομένῃ), οὐδ' ὑμῶν τινες ἀρνήσασθαι δύνανται. ὥστε καλὸν ἂν εἴη ὑμᾶς, ὦ ἄνδρες, ἃ μὴ νενοήκατε, παρὰ τῶν λαβόντων χάριν ἀπὸ τοῦ θεοῦ ἡμῶν τῶν Χριστιανῶν μανθάνειν, ἀλλὰ μὴ κατὰ πάντα ἀγωνίζεσθαι τὰ ὑμέτερα διδάγματα κρατύνειν, ἀτιμάζοντας τὰ τοῦ θεοῦ.
Tertullian, Against the Jews, 9.12: 12 For about the present of gold, David also says, "And it will be given to him from the gold of Assyria" (= Psalm 72.15), and again, "The kings of the Arabs and of Saba will bring him gifts" (= Psalm 72.10). For the East, on the one hand, generally has had the Magi as kings, and on the other, Damascus used to be counted in Arabia, before it was transferred to Syrophoenicia after the dividing up of the Syrias. It was then that the Christ received its wealth, by receiving its symbols, namely gold and spices; while, as for the plunder of Samaria, it is the Magi themselves, who — when they had discovered him and honored him with presents, and had worshipped him as Lord and king by bending the knee on the evidence of the star that was their guide and leader — were made the plunder of Samaria, that is, of idolatry, because they believed in Christ. / 12 Nam de hoc auri munere etiam David dicit, «Et dabitur illi ex auro Arabiae,» et rursus, «Reges Arabum et Saba dona adferent illi.» et magos reges fere habuit oriens et Damascus Arabiae retro deputabatur, antequam transscripta esset in Syrophoenicen ex distinctione Syriarum. cuius tunc virtutem Christus accepit accipiendo insignia eius, aurum scilicet et odores, spolia autem Samariae ipsos magos, qui, cum illum cognovissent et muneribus honorassent et genu posito adorassent qua dominum et regem sub testimonio indicis et ducis stellae, spolia sunt facti Samariae id est idololatriae, credentes videlicet in Christum.
Geoffrey D. Dunn, Tertullian (The Early Church Fathers), page 123, note 106: 106 Justin, Dialogue with Trypho 78.10, reports this transfer of Damascus from Arabia to Syrophoenicia, but without indicating that it happened when Syria was split into two. Herodian 2.7.4 reports that Pescennius Niger was governor of the whole province in 193. It was soon after this that Septimius Severus divided Syria into Syria Coele and Syria Phoenicia. See Birley (1988:114). If this is correct then the comment in Justin must be a later gloss or an indication that even before the split Syria had acquired the name Syria Phoenicia.
It is explanatory; it is cleanly removable; and its value to the point at hand is negligible. (It even mildly contradicts
Justin's point.) Furthermore, it adds a third time frame to the text; Justin has affirmed that Damascus both was
(in the past, at the time of Christ) and is
(in the present, his own time) in Arabia. The idea is that you, the reader, can check for yourself that Damascus fulfills the prophecy about Arabia (via
Rama). The gloss introduces another time frame which nominally is the same as Justin's, namely now
(in the present, νῦν), but which offers the change of name as something which might impede one's ability to check.
I can imagine the author himself inserting the gloss as a way of affirming that, while the official name change has put Damascus in Syrophoenicia, we are still aware that it is "really" in Arabia. But I do not think that we are bound to this interpretation if it does not mesh with what else we know about the Dialogue
. The explanatory gloss option looks very much like an option.