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Brief Overview of Tubothalamea
Tubothalamea is the name given by Pawlowski et al. (2013: Fig 1) to a monophyletic taxon, or subclade, within the more inclusive clade Foraminifera. The authors employ a rank-based system of nomenclature (e.g, Linnean nomenclature), assigning the taxonomic rank of Class to Tubothalamea.
The diagnostic morphological characters of Tubothalamea as given by Pawlowski et al. (2013: 8)are as follows: “ bi- or multi-chambered test with tubular chambers at least in the juvenile stage; wall agglutinated or calcareous; in ancestral forms the test is composed of a spherical proloculus followed by a spirally enrolled tubular chamber; more evolved forms have multi-chambered tests.” The molecular synapomorphies for the clade Tubothalamea given by Pawlowski et al. (2013: 8)are: a relatively short SSU rRNA gene (2289-2866 nt), and a very low (<30%) GC content.
The taxonomic composition of Tubothalamea as defined by Pawlowski et al. (2013: 8)is: Spirillinida (Spirillina sp., Ammodiscus sp. 1, and Ammodiscus sp. 2), and Miliolida (Cornuspira sp., Triloculina sp., Borelis schlumbergeri, Quinqueloculina seminulum, Peneroplis pertusus, Sorites sp., Amphisorus hemprichii, and Marginopora vertebralis).
The geologic range given for Tubothalamea is Lower Cambrian to Recent.
In reference to the phylogeny of Foraminifera depicted in Figure 1 (Pawlowski et al. 2013: 4), Tubothalamea is more closely related to Clade BM, an unnamed clade comprised of Bathysiphon argenteus + Micrometula sp., than to Globothalamea or any of the basal monothalamiid lineages.
As depicted on the reference phylogeny of Foraminifera (Pawlowski et al. 2013: Fig. 1), in which the node is labeled with drawing of a coiled tube, the name Tubothalamea refers to a node-based crown clade, a clade whose name could also be defined using a node-based phylogenetic definition. See Article 2.2 in the PhyloCode Cantino and de Queiroz (2010)for a detailed explanation of phylogenetic nomenclature. Examples of node-based definitions for Tubothalamea are: “the least inclusive clade containing Marginopora vertebralis Quoy and Gaimard, 1830, and Ammodiscus sp. (GenBank accession: HE998691),” or “the clade originating with the most recent common ancestor of Marginopora vertebralis Quoy and Gaimard, 1830, and Ammodiscus sp. (GenBank accession: HE998691).”