Biodiversity of living benthic foraminifera: How many species are there?

In ecological studies involving the analysis of ∼ 2.4 million living (stained) individual tests, to date ∼ 2140 species of benthic foraminifera have been recorded. Of these 602 species are agglutinated, 341 porcelaneous and 1197 hyaline. The numbers of species in the major environments are: marginal marine 701 (in ∼ 1.5 million individuals), shelf 989 (in ∼ 0.6 million individuals) and deep sea 831 (in ∼ 0.3 million individuals). 381 species occur in more than one major environment. Overall ∼ 33% have abundance of > 10% while ∼ 67% are of minor abundance (< 10%). The majority of species are rare, most are endemic and very few are cosmopolitan (5% or less). To estimate the potential total number of living species the following factors need to be quantified: the proportion of species already named (here considered unlikely to be less than 50% of the potential total), the number of species currently known to be dead but for which living representatives may yet to be found (assumed to be 5% = 107 species), and the proportion of species that are synonyms (10–25% = 214 to 535 species). Assuming that 50% of species have already been named (2140 + 107 = 2247), the potential total ranges from ∼ 3959 to ∼ 4280 species for 10% synonymy to ∼ 3210 to ∼ 3531 species for 25% synonymy.