Asci

 

Ascus base. The asci of Sarcoscypha and also other Sarcoscyphaceae, to the present knowledge, consistently arise from simpe septa. This is in contrast to the other families of the Pezizales, in which the asci mostly arise from croziers.

Ascus apex. See under “Ascus Apex Morphology and Iodine Reaction in Ascomycetes” (in preparation).

 

Ascospores

 

Shape. In S. austriaca and S. jurana the truncate, often indented (notched) poles have the shape of a saddle, so that a turn of the spore for 90° along its longitudinal axis results in a hemispherical to obtuse aspect of both poles. Therefore only about 50% of the spores in a preparation show truncate poles (those seen in front view). This fact is frequently mistaken as a variability in spore shape. If the spores are dead, the degree of truncation or indentation is enhanced because of the absence of an internal cell turgor. The function of this peculiar spore shape is unknown; germination appears never to take place at the saddle but rather at the edges (“shoulders”) or laterally.

 

Mature ascospores of Sarcoscypha, living state

Mature ascospores of Sarcoscypha, living vs. dead state

Sarcoscypha austriaca (Salix, Tübingen,

31.3.2003, leg. H.O. Baral)

Sarcoscypha jurana (Tilia, Luxembourg, 16.3.2003, leg. G. Marson)

 

 

 

 

The strong difference in guttule pattern in the living spores between S. jurana and S. austriaca (left column) completely disappears in dead spores due to coalescence of the oil drops, the spore interior thereby looking quite variable (right column). Therefore, herbarium material older than about 5-10 years is not easy to identify.

 

 

Sarcoscypha coccinea (?macaronesica) (Quercus ilex, Montpellier, 1.2.2004, leg. G. Garcia)

Sarcoscypha coccinea (Ulmus, Montpellier, 22.2.2004, leg. G. Garcia)

 

 

Contents. Characteristic of the genus and perhaps the whole family is the presence of numerous refractive minute oil drops (lipid bodies, LBs) among some larger LBs within the living mature spores. A central area is free of LBs and contains 32 small nuclei (?16 in S. occidentalis). Within Sarcoscypha only the larger LBs are of taxonomic importance for species delimitation. While the large and medium-sized LBs (characteristic of S. jurana and S. austriaca), but also the minute LBs are rapidly seen in living spores, the relatively small LBs of S. coccinea (see photo) and S. macaronesica are easily overlooked among the minute ones. In dead spores the LBs are difficult to see because the cytoplasma gets refractive when observed in a water mount. Mounting in KOH makes the LBs reappear in full strength. However, coalescence of both larger and smaller LBs takes place in many of the dead spores causing a very variable guttule pattern which makes species recognition extremely difficult (see table above). The specific guttule pattern is often already destroyed when the spore powder got dry for only a few hours. On the other hand, some spores may still show the unaltered guttule pattern even in very old herbarium material, helping in recognizing the species.

 

S. jurana: spores inside living asci, with  mucilaginous envelope surronding complete spores. Envelope thick and swollen in left ascus while compressed and high-refractive in right ascus.

Mucilaginous envelope (sheath). In several of the species the mature ascospores are surrounded by a delicate envelope. Within the living mature asci the envelope is normally strongly compressed and of higher refractivity compared to those spores within dead asci or being ejected. During immature stages, however, an envelope is probably present in all taxa. The envelope is a very delicate, evanescent structure which disappears in a watery environment some period of time after ejection, and which is rather impossible to detect in herbarium material. However, sheaths can well be seen in water mounts made from spore prints several years after drying (Peric 2008). The envelope does not stain in aqueous cresyl blue or Toluidin blue, while the spore wall surface stains deep lilac in these reagents (only remnants of dead epiplasma around the envelope stain violet).

The shape of the envelope is rather constant within a species and serves as a valuable characteristic for species delimitation. However, the envelope may be absent depending on the geographical origin. S. austriaca usually has polar cap-like envelopes, but sometimes no envelope at all. S. coccinea in Europe is completely devoid of an envelope while in N-America an envelope around the whole spore similar as in S. jurana is present (Harrington 1990).

 

 

 

 

 

 

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