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Name derivation: |
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Name derivation: Petrocelis= cf. L. petra, rock or stone Petrocelis middendorfii is the sporophytic stage of Mastocarpus mammilatus on the Pacific Coast of North America, while P. cruenta is the sporophytic stage of Mastocarpus stellatus in the North Atlantic Common names= tar spot, tar cells or rock overlay |
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Classification: |
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Petrocelis J.Agardh 1851; 3 of 9 species descriptions are currently accepted taxonomically (Guiry and Guiry 2014).Petrocelis can be seen as a synonym with Gigartina on the basis of culture and crossing results. tetraspores derived from Petrocelis were shown to have gametophytes with morphological, anatomical and reproductive characters of Gigartina (Guiry and West 1983). This is due to Petrocelis’ ability to hybridize and adapt to different environments (Guiry and West 1983). |
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Morphology: |
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Tetrasporophytes form soft, spongy greenish, reddish-brown, or purplish-black patches (as Petrocelis cruenta or P. middendorfii), which are up to 50 cm wide, 2 mm thick and closely adherent to rocky surfaces. Crusts often have concentric zones. The hypothallus consists of prostrate filaments connected by secondary pits that bear erect vertical perithallial filaments 3-4 (-7) mm in diam., may be dichotomously branched, and rarely connected laterally. Tetrasporangia are to 20 mm in diam., cruciate, intercalary, and in the vertical filaments. See Mastocarpus stellatus for further information. Petrocelis deviates from the Polysiphonia-type life history, which is not commonly seen in Gigartinales. Their life history is extremely complex with multiple deviations and branches. The family is known only in the tetraspore phase of life history and is highly hybridized (West 1972). |
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Similar genera: |
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Seasonality: |
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Crust surface is not as static as previously believed. From October to January, the crust surface area decreased significantly and from February to August increased significantly to levels seen in early October (Sussmann and DeWreede 2001). This shows a dynamic growth pattern and fluctuations in the growth of Petrocelis. |
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Habitat: |
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Common, but often overlooked, growing within the mid littoral to shallow sublittoral zones on rocky ledges and large boulders, particularly on the open coast. The endophytic green alga ‘Codiolum petrocelidis’ is often found within its tissues. |
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References: |
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Abbott I. A., and G. J. Hollenberg 1976. Marine Algae of California. Stanford University Press, Stanford, xii + 827 pp. Agardh, J.G. 1851. Species genera et ordines algarum, seu descriptiones succinctae specierum, generum et ordinum, quibus algarum regnum constituitur. Volumen secundum: algas florideas complectens. Part 2, fasc. 1. pp. 337 [bis]-351 [bis] 352-506. Lundae [Lund]: C.W.K. Gleerup. Bird. C. and J. McLachlan 1976. Investigations of the marine algae of Nova Scotia. XII. The flora of Pomquet Harbor. Can. J. Bot. 54: 2726-2737. Chen, L. C., T. Edelstein and J. McLachlan 1974. The life history of Gigartina stellata (Stackh.) Batt. (Rhodophyceae, Gigartinales) in culture. Phycologia 13: 287-294. Edelstein, T. , L. C.-M Chen and J. McLachlan 1974. The reproductive structures of Gigartina stellata (Stackh.) Batt. (Gigartinales, Rhodophyceae) in nature and culture. Phycologia 13: 99-107. Guiry, M.D. and G.M. Guiry 2014. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 2 May 2014. Guiry, M.D. and J.A. West 1983. Life history and hybridization studies on Gigartina stellata and Petrocelis Rueness, J. 1978. A note on development and reproduction in Gigartina stellata (Rhodophycae, Gigartinales) from Norway. Br. Phycol. J. 13: 87-90. Sussmann, A.V. and R.E. DeWreede 2001. Seasonality of the red algal crust ‘Petrocelis franciscana’ (Gigartinales, Rhodophyta) on boulder-strewn shores of southern British Columbia, Canada. Phycological Research 49: 51-59.Taylor, W. R. 1957. Marine Algae of the Northeastern Coast of North America. Revised edition. Univ. Michigan Press., Ann Arbor, ix + 509 pp. West, J.A. 1972. The life history of Petrocelis franciscana. British Phycological Journal 7(3): 299-308. |
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