Optional ergativity and information structure in Beria

Ergativity in Africa is rare; König (2008: 95–96) lists only twelve African languages that
have been described as exhibiting ergative phenomena. Even more rarely does optional
ergative marking (OEM) appear, in which the use of an ergative marker may depend on
information-structural or discourse-pragmatic considerations. McGregor (2010: 1631) lists a
sole instance in Africa.
Previous literature on Beria, a Saharan language, describes a system of focus marking that
shows ergative alignment, wherein one marker, =gu, focuses transitive actors (A) and an-
other, =di, focuses either transitive patients (P) or intransitive single arguments (S) (Jakobi
& Crass 2004: 151–154; Jakobi 2006).
Based on new data from texts and judicious elicitation, we suggest that this =gu functions
as an optional ergative marker which speakers employ in diverse pragmatic and syntac-
tic contexts, not simply for assigning argument focus to the A term (Lambrecht 1994) but
also for identifying an A when the P term is in focus; for highlighting brand new A partic-
ipants (Prince 1981) in sentence focus contexts; for disambiguating grammatical roles; and
for marking the A of quotative constructions and embedded relative clauses.
We reanalyze =di as a specificational copula (Mikkelsen 2005), contrasting with the predi-
cational copula =i. Speakers may use either of these copulas in cleft constructions in order
to focus constituents other than transitive actors.