Lichen Morphology III

Reproductive Structures:Reproductive Structures:Asexual and SexualAsexual and Sexual

Asexual Reproduction in Lichens

Symbiotic asexual Symbiotic asexual propagulespropagules

SorediaSorediaIsidiaIsidiaLobulesLobules

Vegetative, nonVegetative, non--symbiotic symbiotic reproductionreproduction

ConidiaConidia on on conidiophores conidiophores produced in produced in pycnidiapycnidia

Symbiotic Propagules: Soredia

Contain both fungal hyphae and photobiont Contain both fungal hyphae and photobiont cellscellsDevelop from outgrowth of the medulla Develop from outgrowth of the medulla forming compact, rounded granules ranging forming compact, rounded granules ranging from 20from 20--5050μμm in diameterm in diameterMay be in regular, delimited May be in regular, delimited soraliasoralia

Soredia (cont.)

Described as Described as marginal, laminal, marginal, laminal, pustulate, granular, pustulate, granular, farinose, labriform, farinose, labriform, involute, etc.involute, etc.Distributed by wind, Distributed by wind, water, animalswater, animals

Punctelia subrudecta

Sorediate Lichens

Pseudocyphellaria withmarginal, yellow soredia

More Sorediate Examples

Parmotrema with marginal cilia and soredia

Isidia

Simple, warty, globose or coralloid Simple, warty, globose or coralloid outgrowths of the medulla with a cortical outgrowths of the medulla with a cortical coveringcoveringEasily broken and distributed as Easily broken and distributed as ““fragmentsfragments”” with both partnerswith both partnersCan degenerate in some taxa into isidioid Can degenerate in some taxa into isidioid soredia, or they can arise from sorediate soredia, or they can arise from sorediate patchespatches

Isidiate Lichens

Parmotrema with isidia and cilia

Xanthoparmelia with isidia

Isidiate Lichens (cont.)

Xanthoparmelia mexicana

Isidiate Lichens (cont.)

SEM of Bulbothrixwith isidia

Lobules

Flattened, corticate Flattened, corticate ““flapsflaps””of thallus tissue on the of thallus tissue on the margins or surface of some margins or surface of some foliose speciesfoliose speciesNot as easily dislodged Not as easily dislodged from the thallus as isidia from the thallus as isidia and may only rarely and may only rarely function in reproductionfunction in reproduction

Pycnidia and Conidia

Tiny, flaskTiny, flask--like or globose fungal structures like or globose fungal structures embedded in the thallusembedded in the thallusInside, Inside, conidiophoresconidiophores bear one or more bear one or more conidiaconidia at the tipsat the tipsMay reproduce the fungus or function as May reproduce the fungus or function as male gamete in sexual reproductionmale gamete in sexual reproductionType, size, shape, etc. is important Type, size, shape, etc. is important taxonomically in some groupstaxonomically in some groups

Pycnidia in Punctelia

Tiny black “dots” are pycnidia

Sexual Structures

LichenLichen--forming Ascomycota and forming Ascomycota and BasidiomycotaBasidiomycota

Formation of Ascomata

Two fundamental types of ascomata occur Two fundamental types of ascomata occur in the lichenin the lichen--forming fungi:forming fungi:

ASCOHYMENIALASCOHYMENIAL forms in which the forms in which the ascomata develop from generative tissue ascomata develop from generative tissue derived from the individual ascogenous hyphae derived from the individual ascogenous hyphae (n+n) and nearby haploid (n) hyphae(n+n) and nearby haploid (n) hyphaeASCOLOCULARASCOLOCULAR forms where the ascomata forms where the ascomata arise in a preformed arise in a preformed stromastroma

Sexual Reproduction: Ascomata

MazaediaMazaediaApotheciaApothecia

LecanorineLecanorineLecideineLecideineBiatorineBiatorineZeorineZeorine

PeritheciaPeritheciaHysterotheciaHysterotheciaPseudothecia Pseudothecia (ascolocular)(ascolocular)

The Mazaedium

Type of ascoma (ascocarp) produced in Type of ascoma (ascocarp) produced in members of the Order Calicialesmembers of the Order CalicialesDisc and ascal walls disintegrates Disc and ascal walls disintegrates ((prototunicateprototunicate) at maturity leaving an ) at maturity leaving an amorphous mass of paraphyses and sporesamorphous mass of paraphyses and sporesLocal species, Local species, Cyphelium Cyphelium notarissiinotarissii, a , a common lichen on fence posts, has this type common lichen on fence posts, has this type of ascomaof ascoma

Structure of Apothecia

Lecideine Apothecium Lecanorine Apothecium

thalloid exciple

properexciple

hymeniumwith

paraphyses

asci andascospores

hypothecium

Apothecial Section

Lecanorine Apothecia

Produces a distinct Produces a distinct thalloid exciplethalloid exciple with with photobiont cells presentphotobiont cells presentDisc and exciple are different in color, Disc and exciple are different in color, and where the exciple and the thallus are and where the exciple and the thallus are the same colorthe same colorWidespread in many lichen families and Widespread in many lichen families and generagenera

Lecanorine Apothecia (cont.)

Haematomma Hypogymnia

Lecideine ApotheciaProduces a Produces a proper excipleproper exciple lacking lacking photobiont cellsphotobiont cellsDisc and exciple are the same color, which Disc and exciple are the same color, which is different from the thallusis different from the thallusExciple and disc are usually black Exciple and disc are usually black (carbonized)(carbonized)Also common in many lichen families and Also common in many lichen families and generagenera

Lecideine Apothecia (cont.)

Porpidia

Biatorine and Zeorine Apothecia

Biatorine apothecia are like lecideine Biatorine apothecia are like lecideine types, except that the exciple is not types, except that the exciple is not carbonizedcarbonizedZeorine apothecia are distinguished by Zeorine apothecia are distinguished by the presence of distinct proper the presence of distinct proper andandthalloid exciplesthalloid exciples

PeritheciaBottle or flaskBottle or flask--like ascomata embedded in like ascomata embedded in the thallusthe thallusOccur in both crustose and some umbilicate Occur in both crustose and some umbilicate and squamulose forms (and squamulose forms (DermatocarponDermatocarpon))The exciple is carbonized in some genera The exciple is carbonized in some genera ((VerrucariaVerrucaria))The ostiole can also have a carbonized The ostiole can also have a carbonized shieldshield--like layer the like layer the involucrelluminvolucrellum

Perithecia (cont.)

Perithecia in crustose lichen Pyrenula

Hysterothecia

Elongated or branched ascomata with a Elongated or branched ascomata with a ““splitsplit--likelike”” hymeniumhymeniumThey may be derived from perithecia (in They may be derived from perithecia (in other fungi) or apothecia (as in lichens)other fungi) or apothecia (as in lichens)Most lichens with this type of ascoma are Most lichens with this type of ascoma are termed termed ““graphidsgraphids””

Hysterothecia (cont.)

Hysterothecia of Phaeographis on bark

Pseudothecia

AscolocularAscolocular originoriginResemble perithecia Resemble perithecia (especially in (especially in crustose, embedded crustose, embedded species) or apothecia species) or apothecia (as in the example at (as in the example at the right)the right)Asci always Asci always bitunicatebitunicate

Niebla

Pseudothecia (cont.)

Locules with asci and ascospores embedded in a stroma (Melanotheca)

Here, the pseudothecia resemble perithecia.

Ascus Structure

Prototunicate asci (ascohymenial Caliciales)Prototunicate asci (ascohymenial Caliciales)Single layer ascus wall with no apical Single layer ascus wall with no apical apparatus for spore releaseapparatus for spore releaseUsually the thin wall disintegrates at Usually the thin wall disintegrates at maturitymaturity

Unitunicate asci (ascohymenial taxa only)Unitunicate asci (ascohymenial taxa only)Actually have a 2Actually have a 2--layered wall which, layered wall which, however, functions as onehowever, functions as one

Ascus Structure (cont.)

The apical apparatus elongation does not The apical apparatus elongation does not cause the two wall layers to separate; the cause the two wall layers to separate; the ascus is described as ascus is described as nonnon--fissitunicatefissitunicate

Bitunicate asci (ascohymenial and Bitunicate asci (ascohymenial and ascolocular taxa) ascolocular taxa)

Asci with two separate layers where the Asci with two separate layers where the inner layer separates and elongates during inner layer separates and elongates during spore release; this type of ascus is described spore release; this type of ascus is described as as fissitunicatefissitunicate

Ascohymenial, bitunicate type

Ascus structure and sporerelease in Peltigera

Ascospore Diversity

Simple sporesSimple spores are single cells with no are single cells with no septations; often small and usually thinseptations; often small and usually thin--walled; generally walled; generally hyalinehyaline (colorless)(colorless)Transversely septateTransversely septate sporesspores have one to have one to many septa; hyaline or brownishmany septa; hyaline or brownishMuriform sporesMuriform spores are multiseptate with are multiseptate with transverse and longitudinal walls; often transverse and longitudinal walls; often large and either hyaline or green to brown large and either hyaline or green to brown

Ascospore Diversity (cont.)

Polarilocular (polaribilocular) sporesPolarilocular (polaribilocular) sporeshave a thick median traversed by an have a thick median traversed by an ““isthmus;isthmus;”” spores are hyaline and spores are hyaline and characteristic of the family Teloschistaceaecharacteristic of the family TeloschistaceaeOrnamentation (as in other fungi) is rareOrnamentation (as in other fungi) is rareSpore morphology, as well as number per Spore morphology, as well as number per ascus, is often important in the ascus, is often important in the characterization of species and generacharacterization of species and genera

Ascospore Diversity (cont.)

Simple

MuriformTransversely

septate

Polarilocular

1-Septate

Basidiomycete Lichens

Reproduction is the same as in freeReproduction is the same as in free--living living basidiomycetesbasidiomycetesBasidiomata are structurally the same but with the Basidiomata are structurally the same but with the addition of photobiont cellsaddition of photobiont cells

Multiclavula Omphalina