Abstract:

 In the present paper a new species of Lasallia Merat is described and placed under

a new subgenus Pleiogyra, characterized by having econcentrical multi-gyrate apothecia. In

consequence of this finding, the conception of plane disc in the genus Lasallia of Umbili-

cariaceae becomes untenable.

     As a result of careful examination of rich materials, the writer considers the dif-

ference in disc found by Scholander among all species of the family is of certain signifi-

cance for classification.  Unfortunately, Scholander’s classification is based solely on this

rather variable morphological character.  If his view be adopted the new species will have

to be inserted into the genus Gyrophora Ach. emend. Schol.  If accepting Llano’s division

of Umbilicariaceae into five genera, namely Lasallia, Agyrophora, Omphalodiscus, Umbili-

caria and Actinogyra, the new species will have to be considered a new  genus  of  the

family.

     The present writer considers both Scholander’s and Llano’s systems as being artificial,

because the former author emphasizes too much the unstable morphological appearance of

disc and the later simply divides the family into five genera simultaneously on the basis

of the stable and unstable characters of the various groups.  In contrast with Scholander’s

and Llano’s systems Frey’s classification neglects wholly the difference in the characters of

disc.  Such treatment is likewise unsound.  The present writer supports the view held by

Flotow, Koerber, Elenkin and Savicz (1950).  Nevertheless, he does not agree with Savicz

in erecting the subgenus Gyrophoropsis (Elenk. et Savicz) Savicz, because muriform spores

are present not only in the group having gyrate discs, but also in the groups having plane

and omphalic discs of the Genus Umbilicaria Hoffm. emend. Vej.  The recognition of this

subgenus must therefore deny the basis on which the other four subgenera are established.

      The system of Umbilicariaceae held by the writer is as follows:

I. Genus Lasallia Merat emend. Vej  ......  Thallus pustulate; disc plane to econcentrical multi-gyrate; spores

    1(2) per ascus, quite large, muriform.

    1. Subgenus Lasallia...Disc plane.

   2. Subgenus Pleiogyra Vej  ......  Disc econcentrical multigyrate.

II. Genus Umbilicaria Hoffm. emend. Vej (syn. Gyrophora Ach. emend. Savicz)* ...Thallus non-pustulate;

   disc plane and smooth or plane with central sterile column (or fissure) or with gyri; spores 8 per ascus,

   simple, hyaline or becoming brown muriform, small.

1. Subgenns Agyrophora (Nyl.) Savicz  ......  Disc plane.

   (1) Section Agyrophora (syn. sect. Anthracinae emend. Llano). .....  Spores simple and hyaline.

   (2) Section Dichroae Llano  ......  Spores becoming brown muriform.

2. Subgenus Omphalodiscus (Schol.) Savicz  ......  Disc with central sterile column or fissure.

   (1) Section Omphalodiscus (syn. sect. Decussatae Schol.)  ......  Spores simple and hyaline.

   (2) Section Spodochroae Schol.  .....  Spores becoming muriform.

3. Subgenus Umbilicaria...Disc with concentrical gyri; spores simple and hyaline or becoming muriform.

   (1) Section Umbilicaria (syn. sect. Simplices Llano)  ......  Spores simple and hyaline.

   (2) Section Gyrophoropsis (Elenk. et Savicz) A. Zahlbr. (syn. sect. Muriformes Llano)  ......  Spores

         becoming muriform.

4. Subgenus Actinogyra (Schol.) Savicz  ......  Disc with radial gyri, proper margin absent.