Does phylogenetic conservatism obscure the trophic ecology of the Small-Eyed Goby Austrolethops wardi Whitley, 1935 (Teleostei, Gobiidae), an inhabitant of shrimp burrows?

Gobiid fishes represent a species rich and ecologically diverse group of Teleostei. Some goby species are known to form obligate associations with burrow-dwelling shrimps. Aside from these mutualistic associations, where fish and shrimp leave the burrow, Austrolethops wardi Whitley, 1935 stays permanently in the burrow of the host-shrimp. Most gobies, also those co-occurring with shrimps, are carnivorous and predominantly feed on mobile zoobenthos. However, A. wardi is herbivorous and feeds exclusively on seagrass. We studied if the oral and pharyngeal jaws and teeth of this species exhibit special adaptations to process seagrass, a relatively nutrition poor food source. While in our study the premaxilla and maxilla significantly differed in shape from carnivorous gobiids, dentition, gill rakers and pharyngeal jaws looked very similar to the compared carnivore species. Although having a specialized diet, A. wardi showed hardly any specific adaptations in its feeding apparatus, which rather reflects its carnivorous ancestry.