Niche-restriction and regional endemism driving facultative
coevolutionary symbiosis --- Ecology and phylogeography of two new
snapping shrimps associated with a gobiid fish
Abstract
Using ecological, taxonomic and phylogenetic approaches, we here
describe geographically isolated symbiotic relationships between a
gobiid fish and two misdescribed alpheid snapping shrimps. This was
discovered in the southwestern province of the Persian Gulf, more
specifically, in the harsh hyperarid intertidal zone separating the
coastal ecosystem from the Middle East desert. Phylogenetic results
based on the 16S rRNA gene indicate the existence of two new cryptic
species within the Alpheus lobidens De Haan, 1849 species complex,
described and named here as Alpheus qatari n. sp. and Alpheus arabicus
n. sp. Furthermore, phylogeographic results suggest resurrection of
Alpheus crassimanus Heller, 1865 within the same species complex. A
phylogenetic comparison of the endemic Arabic goby Cryptocentroides
arabicus (Gmelin, 1789) with some of its congeners confirms its presence
along both sides of the Persian Gulf. Ecologically noteworthy is the
facultative symbiotic interaction between this endemic Arabic goby with
the two mentioned endemic alpheid shrimps within two distinct
ecosystems. Therefore, we herewith report a case of exceptional
symbiosis of a littoral fish species with two potential partners,
niche-restricted to shallow intertidal zones, however, with niche
differentiation defined by the adaptability of each associated shrimp
species. Furthermore, the presence of the goby depends on suitable
sediment needed for burrowing: either gravel in the periphery of coral
reefs, or mud in the periphery of mangrove ecosystems. The corresponding
ecology, taxonomic status and phylogeography are discussed with respect
to the recorded facultative character of the symbiotic relationship.