RED ALGAE · RHODOPHYTA WEEK 2 Notebook Requirements (22 Drawings) 1) Rhodymenia Spp
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RED ALGAE · RHODOPHYTA WEEK 2 Notebook Requirements (22 drawings) 1) Rhodymenia spp. -2 drawings (thallus and cross section) 2) Callophyllis spp-2 drawings (thallus and cross section) 3) Mazzaella spp.- 6 drawings (3 thallus drawings, 3 cross sections) 4) Mastocarpus species complex- 3 drawings (2 thallus drawings and 1 cross section of the tetrasporphyte) 5) Endocladia muricata- 2 drawings (thallus under dissecting scope and cross section) 6) Caliarthron spp.& Mesophyllum spp- 2 drawings (thallus and cross section) 7) Bossiella spp.- 1 drawing 8) Corrallina spp- 1 drawing 9) Unknowns- 3 drawings & keying steps Class Florideophyceae cont. E. Order Rhodymeniales Thalli multiaxial; plants erect to decumbent or creeping; branches solid or hollow; tetrasporangia embedded just beneath surface, scattered or in sori, cruciate or tetrahedral. Species: Rhodymenia 1. Draw thallus. 2. Prepare a cross section and use the compound scope to observe. 3. Draw cross section of internal structure. Look for large isodiametric medullary cells that grade to small cortical cells. F. Order Gigartinales Thalli of various morphologies, mostly fleshy, formed by compact aggregation of filaments; tetrasporangia zonately or cruciately divided, scattered and embedded in cortex or grouped in deep internal sori; cells usually small with discoid chloroplasts, without pyrenoids. Uni- or multiaxial species. Species: Callophyllis 1. Draw thallus. 2. Prepare a cross section and use the compound scope to observe 3. Draw cross section of internal structure. Look for medullary cells mixed with branched filaments (see figure on page 462 in MAC to see uniseriate filaments mixed with medullary cells). Q: Compare and contrast the external and internal structure of Rhodymenia with the external and internal structure of Callophyllis. In what ways do they look the same and in what ways do they look different? Species: Mastocarpus papillatus species complex (C. Agardh) Lindstrom Mastocarpus demonstrates heteromorphic alternation of generations. The two generations are: Mastocarpus = upright, gametophyte/carposporophyte “Petrocelis” stage = crustose pseudoparenchymatous tetrasporophyte 1. Draw the thallus of Mastocarpus gametophyte & carposporophyte 2. Make a cross section of the crustose stage. Draw the filament orientation and look for tetrasporangia. If they are present, include the tetrasporangia in your drawing. Q: What type of tetrasporangia does the “Petrocelis” stage have? (see diagram below) Cruciate Zonate Tetrahedral Q: Which alga is the 1N stage and which is the 2N stage? Species: Mazzaella flaccida (forme rl y Iridaea flaccida) 1. Draw the thallus and a cross section of all three life history stages of Mazzaella. Be able to recognize all three life history phases. Label the cortex, medulla, and reproductive structures. Carposporophyte = Large bumps Tetrasporophyte = Small bumps Male Gametophyte = Smooth Q: What is the thallus construction of this alga? Q: What type of tetrasporangia does Mazzaella have? (See diagram above) Species: Endocladia muricata Prepare a macroscopic piece of the thallus for the dissecting scope, a cross section for the compound scope, and observe: 1. Draw the external morphology & draw the cross section. Q: Is this algae uniaxial or multiaxial? 2. Reproductive features. Look for the wart-like, golden, elevated bumps on branches bearing female reproductive structures. These are called nemathecia. 3. Note tiny co nical spines on the side of the thallus. What is their function? G. Order Corallinales A group of calcified red algae with thalli of crustose bases and articulated fronds; usually saxicolous, sometimes epiphytic or epizoic. Coralline algae may be non- geniculate or geniculate. The non-geniculate coralline algae are crustose, forming a thin, prostrate mass of modified filaments on the substrate. Geniculate corallines are articulated into two tissue types: genicula and intergenicula. The genicula are made of filaments only, and are not calcified, while both cortex and filaments make up the calcified intergenicula. The intergenicular medulla are composed of arching tiers of cells of same length. Geniculate Species: Calliarthron spp, Bossiella spp. & Corallina spp 1. Decalcify a small portion of Caliarthron with 5% HCl for 1 hour prior to sectioning. 2. Draw decalcified sample, label genicula and intergenicula. 3. Section through a conceptacle to view tetrasporangia. Sketch a conceptacle and a tetrasporangium. What type of tetrasporangium did you find? See diagram above. Observe and sketch: 4. External structure of Bosiella & Corralina spp. Label conceptacles,genicula and intergenicula. Non-geniculate Species: Mesophyllum sp. Mesophyllum is a non-geniculate alga, found epiphytically on geniculate corallines. 4. Draw the thallus of Mesophyllum on the geniculate alga it was found on. Unknowns- Write out steps for key and draw external thallus of the 3 unknowns. .