Observation 122551: Leptogium gelatinosum (With.) J.R. Laundon

When: 2013-01-05

Collection location: Sintra, Portugal [Click for map]

Who: zaca

No specimen available

Habitat: a vertical wall covered with moss and other plants (e.g. liverwort) in a wetland inside a natural park. Living together with other Leptogium spp., e.g. L. cochleatum, L. cyanescens.
The first question that naturally arises is: Collema or Leptogium? The color of the thallus suggest the second and the microscopy reinforces this choice, by the existence of a cortical layer of rounded cells in a kind of reticulate (see the central photo in the first set of photos from microscopy).
Secondly, there are a number of species with similar features, namely L. gelatinosum, L. lichenoides and L. pulvinatum, being macroscopically separated by the properties of the thallus at the margin of lobes: isidia absent (the 1st and 3rd) or present and cylindrical (the 2nd). Since it seems to me that this specimens lacks isidia, this rules out L. lichenoides. The margin is entire or with regularly lanceolate margins in L. gelatinosum, and the lobes are much divided with fimbriate margins in L. pulvinatum. This clearly points to L. gelatinosum. Moreover, this species is frequently fertil with red-brown or brown discs, which is the present case.
However, there a point in doubt: Both species have muriform spores with dimensions in the range 22-42 × 11-17 µm (I obtained the average dimensions of 26 × 11, with all values very close to the means), with 5-7 (9) transversal septa, but I could observe at most 3 or 4 transverse septa.


Microscopy – Cortical layer and some spores;
Microscopy – Asci.

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Created: 2013-01-10 13:46:31 PST (-0800)
Last modified: 2013-01-10 13:47:16 PST (-0800)
Viewed: 14 times, last viewed: 2018-02-05 00:51:14 PST (-0800)
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