San Salvatore in Primicerio was a confraternity church that used to stand in Via dei Tre Archi in the rione Ponte.
It was founded in 1113 by Pope Paschal II, and we know this because an epigraph recording the fact used to be preserved in the church. It was dependent on the parish church of San Lorenzo in Damaso at first, but soon became parochial in its own right.
An alternative early name was de Locero, and in the 16th century it was also known as alla Volpe. A nickname was San Salvatorello, owing to its small size.
In 1604 the church was taken over by the Confraternita dei Santi Trifone e Camillo, which was dedicated to the veneration of the Blessed Sacrament. They had originally been based at the ancient church of San Trifone, but this had been subsumed into the monastery attached to the new basilica of Sant'Agostino and was later demolished to extend the monastic buildings.
At first the confraternity seems to have struggled, because in 1676 it was reported that the church had been in a derelict state and had been restored at the personal expense of the priest in charge. Then, in 1694 it was reported as having been closed down. However the confraternity then managed to get its affairs in order, and the church was subsequently usually known as San Trifone. The parish was suppressed.
This renaming has obviously caused confusion with the ancient church, which was often known as San Trifone in Posterula. The "info.roma" web-page gives one example of this mistaken identity. Any reference mentioning in Posterula does not refer to this church, but to the ancient one.
Towards the end of its life, the church was also called Santa Maria del Buon Consiglio in Campo Marzio because it contained a venerated icon of Our Lady of Good Counsel.
It was finally demolished for secular redevelopment by 1940.
This one was never easy to find. It was in a very picturesque little network of alleyways in between Via dei Coronari and Via della Maschera d'Oro, east of the Piazza Lancelotti. The Via dei Tre Archi starts at the piazza and runs east. An alleyway known as the Vicolo di San Trifone runs south from Via della Maschera d'Oro to join it, and the church stood on the junction. The façade was on the vicolo, and the left hand side wall ran along the Via dei Tre Archi.
The postal address of the building that replaced the church is Vicolo di San Trifone 1.
It was a simple edifice, on a rectangular plan divided into three bays by three pilasters on each side wall. There were two side altars.
When the church was demolished, the entrance doorcase was preserved and re-inserted into the replacement edifice. This is the only relic of the church on site, and is a fine piece of stonework in marble. The doorcase itself has moldings, and above the lintel is a frieze bearing a dedicatory inscription reading Ec[clesi]a par[ochialis] S[anctissimi] Salvatoris Primicerii. Above this in turn is a floating cornice.
The old guidebooks indicate that this was a boring little church, with no artworks worthy of notice. Perhaps this explains why there are no images of it online. However two frescoes of saints in chiaroscuro by Giuseppe Chiari, either side of the door, were noted in 1767 and a pair of busts from the early 16th century, deriving from a destroyed tomb, were noted in the same location in the early 20th century.