Gromia winnetoui, Rothe & Gooday & Cedhagen & Fahrni & Hughes & Page & Pearce & Pawlowski, 2009

Rothe, Nina, Gooday, Andrew J., Cedhagen, Tomas, Fahrni, José, Hughes, J. Alan, Page, Anton, Pearce, Richard B. & Pawlowski, Jan, 2009, Three new species of deep-sea Gromia (Protista, Rhizaria) from the bathyal and abyssal Weddell Sea, Antarctica, Zoological Journal of the Linnean Society 157 (3), pp. 451-469 : 466-467

G. WINNETOUI SP. NOV.

The coarsely agglutinated case enclosing the test in G. winnetoui sp. nov. represents the first report of a secondary agglutinated structure in Gromia . Various calcareous, agglutinated, and organic-walled foraminiferan species construct agglutinated cysts ( Heinz, Geslin & Hemleben, 2005): examples include Elphidium incertum (Williamson, 1858) ( Linke & Lutze, 1993) and Nonionellina labradorica (Dawson, 1860) ( Cedhagen, 1996) . However, foraminiferal cysts are often rather diffuse structures, composed of fine sediment particles and detritus. Moreover, as Heinz et al. (2005) note, the cyst is often separated from the test by an open space. The structure enclosing G. winnetoui sp. nov. appears to most closely resemble the agglutinated casing observed in Saccamminid sp. 1 from the continental slope (850-m depth) off Cape Hatteras, North Carolina ( Gooday, Hughes & Levin, 2001; A.J. Gooday, pers. observ.). As in G. winnetoui sp. nov., it is composed of loosely cemented quartz grains, which press closely against the test and leave a clear imprint on the flexible underlying test surface.

The function of the agglutinated case in G. winnetoui sp. nov. is not clear. In the case of foraminifera several authors have distinguished between reproductive cysts, as observed in Patellina corrugata Williamson, 1858 by Meyer (1935), feeding cysts, as described by Jepps (1942) in Elphidium crispum (Linnaeus, 1767) , and growth cysts that are formed at the onset of chamber formation ( Gross, 2002). It has also been observed that cysts serve as adaptations to changes in the environment, by providing protection against mechanical and chemical disturbances ( Linke & Lutze, 1993), as well as by disguising the organism from predators ( Cedhagen, 1996). In the case of G. winnetoui sp. nov., the latter two functions seem the most plausible.

CONCLUDING REMARKS

Until recently, Gromia was only known from shallow waters, and most gromiids were assigned to a single species, G. oviformis ( Burki et al., 2002) . Since the discovery of deep-sea gromiids on the Omani margin of the Arabian Sea in 1994 ( Gooday et al., 2000), an increasing number of deep-water species have been identified and described, based on both morphological and molecular characteristics (Gooday & Bowser, 2005; Aranda da Silva, 2005; Aranda da Silva et al., 2006). Ongoing and future work from different parts of the world will increase the number of species further, and will reveal novel morphotypes that might soon warrant a subdivision of the genus Gromia .