OBSERVATIONS ON LICHENIZED AND FREE‐LIVING PHYSOLINUM (CHLOROPHYTA, TRENTEPOHLIACEAE)¹

Abstract

Lichenized Physolinum Printz and free‐living Physolinum from a dimly lit cave were studied from fresh collections and cultures, preserved specimens fixed in situ, and cultures that had persisted for 5 years in an environmental chamber. The branched filamentous association consists of a phycobiont and a characteristic ascomycetous mycobiont of one layer that completely ensheathes the algal partner. Epiphytic blue‐green algae commonly occur attached to the mycobiont. The phycobiont, Physolinum monilia (De Wildem.) Printz, produces thick‐walled, green spiny cells, some of which enlarge and contact the sheathing mycobiont cells; the phycobiont and mycobiont may then develop into new lichenized filaments. The hyaline mycobiont cells extend haustoria bound by the fungus wall deeply into the phycobiont chloroplasts. The epiphytes, Synechocystis‐like colonies, are firmly attached to the outer walls of the mycobiont and are associated with several‐celled extensions of the fungus beyond the apical phycobiont cells. Free‐living Physolinum monilia filaments are branched and moniliform; the search‐containing uninucleate cells are spherical to pyriform and have walls of cellulose. Each cell has a single massive chloroplast with plastoglobuli among tightly packed thylakoids. Except for their larger cells, P. monilia filaments appear to be identical to the phycobiont of lichenized Physolinum.

Rexia erecta Gen. et sp. nov. and Capsosira lowei sp. nov., Two Newly Described Cyanobacterial Taxa from the Great Smoky Mountains National Park (USA)

“…The phycobiont exhibited a very different morphology when grown on agar plates free of H. venosa, an observation also noted by other researchers studying lichen symbioses (e.g. Bubrick, 1988;Ahmadjian, 1989;Davis & Rands, 1993). Examination of the isolated strain revealed all of the morphological features of Capsosira, including a thallus consisting of rigid, vertical, parallel, knobby trichomes with clustered branches and trichomes formed of a series of single-celled vesicles (sensu Ku¨tzing, 1849) ( Fig.…”

Molecular, biochemical and morphological data suggest an affiliation of Spongiochrysis hawaiiensis with the Trentepohliales (Ulvophyceae, Chlorophyta)

“…T. rigidula (J. Müller) Hariot (= Physolinum monile ), Trentepohlia umbrina (Kützing) Bornet or Printzina lagenifera (Hildebrand) R.H. Thompson & D.E. Wujek and several other species) in which the adjacent cells are connected by a very small area (Cribb ; Davis & Rands ; Ettl & Gärtner, ; Rindi et al . ; Rindi & López‐Bautista ), but the phylogenetic analyses did not confirm any relationship with moniliform species of Trentepohlia .…”

“…Spongiochrysis hawaiiensis occurs mainly as unicells but may form short moniliform filaments of dividing cells (Rindi et al 2006), a mode of growth that is reminiscent of the ease of fragmentation in some moniliform species of the Trentepohliales (e.g. T. rigidula (J. Müller) Hariot (= Physolinum monile), Trentepohlia umbrina (Kützing) Bornet or Printzina lagenifera (Hildebrand) R.H. Thompson & D.E. Wujek and several other species) in which the adjacent cells are connected by a very small area (Cribb 1970;Davis & Rands 1993;Ettl & Gärtner, 1995;Rindi et al 2005;Rindi & López-Bautista 2007), but the phylogenetic analyses did not confirm any relationship with moniliform species of Trentepohlia. No other obvious morphological similarities exist between S. hawaiiensis and any other genera of the Trentepohliales.…”

Plant-Parasitic Algae (Chlorophyta: Trentepohliales) in American Samoa

“…Stomatochroon Palm, 1934, lives in the substomatal chambers of its host and was described as an "obligate endophyte (parasite)" by Chapman and Good (1983) and a commensal organism by Timpano and Pearlmutter (1983). Phycopeltis Millardet, 1870, andPhysolinum Printz, 1921, are supracuticular epiphytes but may be found on other surfaces under very humid or moist conditions (Thompson and Wujek 1992, Davis and Rands 1993, Rindi and Guiry 2002. The free-living algae Trentepohlia Martius, 1817, and Printzina Thompson & Wujek, 1992, occur widely on living and nonliving substrates (Chapman 1984, Rindi and Guiry 2002, Thompson and Wujek 1992.…”