Pawlowski, J.; Holzmann, M.; Debenay, J.-P. (2014). Molecular phylogeny of Carterina spiculotests and related species from New Caledonia. The Journal of Foraminiferal Research. 44(4): 440-450.
Carterina spiculotesta is a common tropical benthic
foraminifer characterized by fusiform or rod-like calcareous
spicules covering the surface of the test. Because of this
peculiar wall feature, the genus Carterina was separated from
other foraminifera and placed in its own suborder (Caterinina)
or order (Carterinida). However, there is no agreement about
the origin of Carterina spicules, which are considered either as
being secreted by the foraminiferal cell or as agglutinated
foreign particles; if the latter case, the genus was placed in the
order Trochamminida. Here, we attempted to resolve this
controversy by analysis of genetic data from various carterinids
collected in New Caledonia. We obtained seven complete
and 47 partial small subunit (SSU) rDNA sequences. Our
results show that all specimens of spicule-bearing Carterina
cluster together in a strongly supported clade. Sister to this
clade are undetermined lineages of trochamminid morphospecies.
Together with its sister groups, the Carterina clade forms
an independent lineage at the base of Globothalamea within the
paraphyletic radiation of textulariids and robertinids. Its exact
phylogenetic position was difficult to establish because the used
SSU rRNA genes lack resolution. As long as experimental
data do not contradict the hypothesis of a secreted origin for
Carterina spicules, we propose to retain the ordinal status of
the Carterina clade, and consider it as one of the orders of the
class Globothalamea. In view of our study, the diversity of this
order may be much higher than traditionally accepted,
including several genera and species, many of them new to
science.