A canonarch is a lead cantor

Cantor (church)

A cantor is the chief singer employed in a church with responsibilities for the ecclesiastical choir; also called the precentor....

, or reader, in Eastern Christian churches of the Byzantine

Byzantine

Byzantine usually refers to the Roman Empire during the Middle Ages.Byzantine may also refer to:* A citizen of the Byzantine Empire, or native Greek during the Middle Ages...

 tradition. The canonarch ensures that other readers chant from the correct texts and use the proper tones

Reciting tone

In chant, a reciting tone is a repeated musical pitch around which the other pitches of the chant gravitate, or by extension, the entire melodic formula that centers on one or two such pitches. In Gregorian chant, reciting tones are used for a number of contexts, including the chanting of psalm...

. The canonarch preserves the canonical order in the liturgical services through proper use of the Typicon.

The canonarch also reads the verses of the prokeimenon

Prokeimenon

In the liturgical practice of the Orthodox Church, a Prokeimenon is a psalm or canticle refrain sung responsorially at certain specified points of the Divine Liturgy or the Divine Office, usually to introduce a scripture reading...

 and related texts. In some churches many of the duties of the canonarch have been assumed by deacon

Deacon

Deacon is a ministry in the Christian Church that is generally associated with service of some kind, but which varies among theological and denominational traditions...

, such as chanting the verses of Theos Kyrios

Theos Kyrios

Theos Kyrios is a psalm response chanted near the beginning of the Matins service in the Rite of Constantinople, observed by the Eastern Orthodox and Byzantine Catholic churches. It is based principally on Psalm 117 , the refrain composed of verses v...

.