Evolutionary aspects of cephalic sensory papillae of the Indo‐Pacific species of Eleotris (Teleostei: Eleotridae)
Abstract
Eleotris species (Teleostei: Eleotridae) are one of the most common fish in Indo‐
Pacific estuaries and insular freshwater streams. In these rivers, they are a sit‐andwait
predator. They have an amphidromous life cycle, that is adults grow, feed and
reproduce in rivers, while larvae have a marine dispersal phase. Larvae recruit back
to rivers and settle in stream habitats. Primary characters used to determine Eleotris
species are the presence and the disposition of cephalic sensory papillae rows on the
operculum and under the eyes as well as scale row numbers. The morphology of
these cephalic sensory papillae is of particular importance in this predatory genus
as it is generally correlated in fish to predation and feeding. In this paper, we have
established a molecular phylogeny of the genus based on the 12 mitochondrial protein‐
coding genes to discuss the relationship between Indo‐Pacific Eleotris species.
There is a well‐supported dichotomy in the molecular phylogeny, and this separation
into two main clades is also morphologically visible, as it reveals a difference in the
arrangement of cephalic sensory papillae. Indeed, the phylogeny distinguishes the
species with the “open” pattern of the operculum sensory papillae and the species
with the “closed” one. This phylogeny thus reflects the morphology of the opercular
papillae. The evolution of this character is discussed in terms of the adaptation of the
Eleotris genus to life in tropical insular river systems.