Sinelobus stromatoliticus sp. nov. (Peracarida: Tanaidacea) found within extant peritidal stromatolites

Living coastal stromatolites, layered structures formed by the microbially mediated precipitation of calcium carbonate, are scarce because of grazing and burrowing disruption by metazoans, amongst other reasons. This paper describes Sinelobus stromatoliticus sp. nov., a tanaidacean living within laminated stromatolites along the South African coastline. S. stromatoliticus is the sixth geographically isolated species now recognised within what was once considered to be a single globally cosmopolitan species, S. stanfordi Richardson, 1901. A revised, sex-specific dichotomous key to all the species currently recognised within this genus is provided. Sinelobus stromatoliticus is a prominent and abundant metazoan within the living stromatolite habitats, yet despite being a burrowing and grazing species, stromatolite layering is not hampered by its presence. Future work should determine the relationship between other populations (cf. S. stanfordi) in South Africa (previously identified as Tanais philetaerus Stebbing, 1904) and those of the stromatolite-dwelling S. stromatoliticus. However, given South Africa’s clear biogeographic zonation in other taxa, it is unlikely that this genus that features no pelagic larval stage would be morphologically similar across biogeographic regions.