Morphological discoveries in the genus Diploneis (Bacillariophyceae) from the tropical west Pacific, including the description of new taxa

Abstract

Epiphytic diatoms on seaweeds and seagrasses were collected from tropical regions in the western Pacific Ocean (i.e., Siladen Island, Celebes Sea, Indonesia; Guam; Palau). Fifteen species of Diploneis are described in detail with light and scanning electron microscopy including six species new to science, D. cerebrum, D. claustra, D. craticula, D. crispa, D. rimosa and D. weissflogiopsis. Valve structure in Diploneis is particularly complicated, and two new distinctive structures are described for the first time: (1) central external raphe endings with flaps or rolled flaps and (2) internal globular papillae near the marginal ends of the virgae. In addition, we confirm that openings on the inner surface of the longitudinal canals are of taxonomic value. The structural complexities encountered in Diploneis require the study of a great many more taxa before a meaningful revision of the genus can be undertaken. Its diversity in warm waters is a rich resource for new Diploneis taxa to further our understanding of the genus.

Keywords:

• Diploneis
• epiphytism
• microphytobenthos
• species diversity
• ultrastructure
• Western Pacific Ocean

Acknowledgments

The authors would like to thank Dr Francesca Azzini for collecting samples in Siladen Island; María Schefter for encouragement and support in fieldwork; Drs Luigi Gobbi and Adriano Di Cristoforo for technical assistance using the SEM; Dr Y.-M Wen from Guam University for drawing the map; and Commanding Officers of Naval Base Guam for access to study sites. Samples in Palau were collected under Koror State Marine Research Permit #09-196 and National permit #RE-09-14.

Additional information

Funding

Dr Michel Poulin received funding from the Canadian Museum of Nature and Dr C. S. Lobban acknowledges NIGMS RISE funding for LM and SEM instruments on Guam.