DESCRIPTION: Parasymbiont on littoral Verrucariae, espe- 

 cially V mucosa and V microspora. lacking a visible thallus of its 

 own. Perithecia usually resembling that of host lichen, totally 

 immersed on V. mucosa and hemispherical on V microsponi. Invo- 

 lucrellum black with pigment extending into hyaline excipulum. 

 Spores eight per ascus. two-celled with each cell often divided by 

 pseudosepta. uppercell usually slightly widerthan the lower, 10-15 

 X 3.5-5/im. 



The perithecia of Stigmidium are easily confused with that of the 

 host. Sligmidium. however, has two-celled spores of 10-15 x 3.5- 

 5/im. Swinscow (1965) reported spores 10-15 x 4-6/im. The com- 

 bination Stigmidium marinum was made by Swinscow when he 

 united Arlhopyrenia marina (Deak ) A. L. Sm and A. leptotera 

 (Nyl. ) Am. Neither of these species appear in the North American 

 checklist (Hale and Culberson 1970) nor did Swinscow (1965) 

 report a specimen from North America. This, therefore, represents 

 a new record for North America. 



GENERAL DISTRIBUTION: Germany, Finland, Ireland, Jer- 

 sey. England (Swinscow 1965). 



NORTHEASTERN AMERICAN DISTRIBUTION: MAINE: 

 Cumberland Co. , Hancock Co. NEW JERSEY: Ocean Co. NEW- 

 FOUNDLAND: Avalon Section. 



Genus Verntcaria 



The species of this genus form crusts which may be contmuous or 

 form scattered patches, rimose areolate or divided into discrete are- 

 oles or lobes. The thalli vary in thickness from 20 to 500/jm, and 

 may be almost completely transparent to entirely opaque. In some 

 species, the transparency of the thallus may be enhanced by wet- 

 ting, while others remain opaque when wet. The thalli may be 

 smooth or roughened by dark points or ridges. The ridges, called 

 juga (Santesson 1939), vary in length, width, and thickness. The 

 exact ongin and ontogeny of the juga is not known but it appears 

 that they originate at or just below the surface of the thallus. In the 

 author's experience, they do not extend to the substrate except at the 

 edges of the areoles. Often a distinction is made in keys between 

 point and ridge forms of the juga, but it is common that the points 

 are merely peaks on inconspicuous or hidden ridges. 



The perithecia of all of the littoral Verrucariae, with which the 

 author has worked, have a dark involucrellum which may spread 

 widely or be closely appressed to the excipulum. This darkening 

 may extend into the lower excipulum, terminating a short distance 

 below the involucrellum proper or it may not extend into the lower 

 excipulum. The darkening may occur intermittently or continu- 

 ously throughout the lower excipulum. This darkening is given 

 considerable taxonomic importance by Servit ( 1954) and by Ench- 

 sen (1957) but Swin.scow ( 1965) discounted this importance on the 

 grounds that it is highly variable within a species. The author con- 

 curs with Swinscow in this view. Perithecial size is not, in itself, 

 very useful in distinguishing species. Perithecium diameters vary 

 generally between 0.05 and 0.7 mm and these dimensions overlap 

 considerably between Verrucaria species. Although vertical sec- 

 tions are illustrated in the key. none is claimed to be typical for then; 

 is much variation in many, if not all species. 



Santesson (1939) has noted the high variability of spore size in 

 littoral pyrcnolichens and suggested that they should not be given 

 great taxonomic importance. All spores in yernicariti are simple 

 and hyaline. For the most part, the spores are thin walled and of 

 similar size, occurring eight per ascus. Verrucaria inlernigrescens 



and V silicicola are the notable exceptions to the above in north- 

 eastern North America. The spores of V. inlernigrescens are thick 

 walled and those of V. silicicola are unusually large. The remainder 

 are ovoid to reniform and exhibit overiapping size ranges between 

 species, 



Verrucaria amphibia R. Clem. Ess. Var Veg. Andalucia 299. 

 1807. 



DESCRIPTION: Thallus continuous to rimose areolate. black 

 when dry. translucent green to amber when wet, with irregular 

 black ndges often enclosing lenticular areas 50-l(X)/im thick. 

 Perithecia large (13-16 mm), prominently elevated, often flattened 

 or concave on top. vertical and horizontal ridges forming reticular 

 pattern, lenticular areas often enclosed by ridges at base; excipu- 

 lum hyaline to partly darkened below. Spores hyaline, ovoid. 7-19 

 X 4-7. 5^m. 



This species might readily be confused with V. maura. Both spe- 

 cies have dark thalli with juga forming pegs or ridges and with 

 robust penthecia. However, they are easily distinguished on closer 

 examination. Whereas V. maura tends to have points raised above 

 the thallus, V. amphibia tends toward ridges. The ridges tend to 

 enclose lenticular areas on a dry thallus giving the impression of 

 ripples on water When wet. V. amphibia becomes more translucent 

 and light colored against which the black ridges become contrasted. 

 The thallus of V. maura remains dark when wet except on very thin 

 juvenile specimens. The thallus of V. amphibia tends to be continu- 

 ous whereas that of V. maura tends to be rimose areolate but in nei- 

 ther case are the characters absolute. Areolation appears to develop 

 and increase with age in V. amphibia. Verrucaria amphibia pro- 

 duces large, steep sided perithecia often strongly depressed on top. 

 a form also produced in some instances by V maura. Such perithe- 

 cia of V. amphibia have two characteristics not demonstrated by V. 

 maura: whereas V. maura may have many fine points or pegs cov- 

 ering the perithecium. the design on V amphibia is a reticulum of 

 vertical and horizontal ridges. Also, where the V amphibia perithe- 

 cium meets the thallus, the ridges tend to enclose areas of ovoid 

 shape and appear light and translucent when wet (see the Key). 



Verrucaria amphibia is little discussed in literature. Santesson- 

 says that it is not known from Scandinavia, although it occurs in 

 England. Ferry and Sheard (1969) included V amphibia in their key 

 but did not deal with it in detail . The author first became acquainted 

 with It by examining herbanum specimens and his measurements 

 should not be regarded as limits due to the small amount of material 

 examined. There is no prior report of this species from North 

 Amenca. 



GENERAL DISTRIBUTION: England (Ferty and Sheard 

 1969). Wales (Fletcher 197.3a). Germany (Ullnch MSC). 



NORTHEASTERN AMERICAN DISTRIBUTION: NEW- 

 FOUNDLAND: East Coast Section. Avalon Section. 



Verrucaria ceuthocarpaWMenb. in Ach. Suppl. Meth. Lich. 22. 

 1803. 



DESCRIPTION: Thallus brown, rimose areolate, glabrous, 

 forming discrete areoles or lobes, ridges absent, perithecia sub- 



-R. SanlcsMin. Dirctlur. S\sienuilic Insiiiute of Oslo. Oslo. Nor^^.;l\. pcrs 

 commun November 146(1. 



17 



