Molecular data show the enigmatic cave-dwelling diatom Diprora (Bacillariophyceae) to be a raphid diatom

• Published in: European journal of phycology 2013-11, Vol.48 (4), p.474-484
• Main Authors: Kociolek, J. Patrick, Stepanek, Joshua G, Lowe, Rex L, Johansen, Jeffrey R, Sherwood, Alison R
• Format: Article
• Language: English
• Subjects: Bacillariophyceae; Bacillariophycidae; caves; chloroplasts; diatoms; Diprora; endemic; genes; Hawaiʻi; phylogeny; ribosomal DNA; trees
• ISSN: 1469-4433; 0967-0262; 1469-4433
• DOI: 10.1080/09670262.2013.860239

The diatom genus Diprora (Bacillariophyceae) was described from a cave on Kauaʻi, Hawaiʻi. Due to its lack of a raphe system and bilateral symmetry, the genus was first assigned to the Fragilariophycidae (‘araphid diatoms’), but its systematic affinities were undetermined. We present a three-gene phylogeny, based on nuclear (SSU rDNA) and chloroplast (rbc L, psb C) genes, to determine the phylogenetic relationships of Diprora in the diatom tree of life. The concatenated multi-gene phylogenies, and the individual genes trees show Diprora to nest deep within the raphid diatoms, and in different analyses (of one-, two- and three-gene sequences) this diatom is shown to be most closely allied with taxa referred currently to the Sellaphoraceae, including Sellaphora or Fallacia . Hypothesis testing of the likelihood of Diprora being an ‘araphid’ diatom indicates rejection of the hypothesis that the phylogenetic position of D. haenaensis is within the araphid diatoms. Loss of the raphe system and reduction of other features may be related to its cave-dwelling habit.