Abstract
Benthic foraminifera, and certainly symbiont-bearing (large) benthic foraminifera are generally considered to have large geographic ranges in combination with significant ecomorphological variation. With the advance of molecular phylogenetic approaches, supported or preceded by detailed morphological studies, it was demonstrated that this view needs to be reevaluated. In this paper I evaluate the morphology of five Marginopora populations from around the Coral Sea by microCT-scanning. I argue that ecomorphological and ontogenetic variation is smaller than geographic variation in morphology. This forms the basis for the description of three new species, M. santoensis nov. spec., M. charlottensis nov. spec., M. orpheusensis nov. spec. Quantitative morphological variation between M. rossi, M. orpheusensis nov. spec. and M. charlottensis nov. spec. is overlapping, but each species has unique morphological characters supporting recognition as new species. Support to distinguish the deep living (M. rossi, M. charlottensis nov. spec., M. orpheusensis nov. spec.) and shallow living (M. vertebralis) Marginopora populations as separate species is strong, but not enough molecular phylogenetic data are available to test the three new deep-living species on the Great Barrier Reef hypothesis. However, detailed understanding of ecophenotypic variation in M. santoensis nov. spec. supports the conclusion that it is unlikely that ecophenotypic variation can explain the morphological variation between the three species. I argue that the number of species in this genus is underestimated, and that there are at least five species in the Coral Sea area alone.
Highlights
Foraminiferal taxonomy, as in other groups of organisms, have been subject to waves of taxonomic splitters and lumpers
The oldest molecular study on Marginopora is by Benzie and Pandolfi [11] who found no significant allozyme differentiation in M. vertebralis populations over the entire Great Barrier Reef
All specimens in [11] were collected at less than 4 m depth (Table 1 in [11]), consistent with the morphological evidence of a single species occurring in reef crest and reef flat environments across the entire Great Barrier Reef
Summary
Foraminiferal taxonomy, as in other groups of organisms, have been subject to waves of taxonomic splitters and lumpers. The importance of ecophenotypic variation was emphasized, and what was previously interpreted as multiple species were lumped into single species with wide geographical ranges and considerable morphological variation [1]. This tendency was especially strong for taxa that are widely used as indicators for either stratigraphy or environmental reconstruction. With the advent of molecular techniques, independent tests of the value of morphological characters became available.
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