Observation 62698: Physcia undulata Moberg

abundant on buttonwoods (Conocarpus erectus) in coastal scrub bayside

Proposed Names

87% (1)
Eye3 Eyes3
Recognized by sight: exclusively marginal soralia (except in oldest parts), pruinose near tips, tips 1-2 mm wide, on bark and wood (occasionally also seen on coral blocks and old ropes)
Used references: Sonoran Flora and More Florida Lichens
Based on microscopic features: upper cortex paraplectenchymatous, spores ~pachysporaria-type, 18-25 × 9-11 µm
Based on chemical features: cortex K+y; medulla K+y turning orange slowly

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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More confusion hopefully at least cleared up…
By: Jason Hollinger (jason)
2011-06-14 12:51:11 PDT (-0700)

Mostly due to general lack of info on this species and the similar (at least on paper) P. poncinsii.

Having become better acquainted with Heterodermia albicans and Heterodermia in general, it is absolutely clear that the K+y to orange medullary reaction which I interpreted as weak norstictic acid does not signify. The upper cortex of Heterodermia is prosoplectencymatous (composed of elongated parallel hyphae) and has a distinctive “flowing” appearance. Physcia has paraplectenchymatous upper cortex (a palisade in mycological terms in this case), which has a uniform, spatially homogenous, dull appearance. Zeorin, it seems, when present in sufficient quantity, can result in a slow darkening of the K reaction (K+y initially due to atranorin in the medulla). (Upon subsequent examination of specimens I’ve already tested, the K+y test is observed to have turned finally dingy orange-red, not dingy brown-yellow as normal for material containing only atranorin.)

From More Florida Lichens: chemistry rules out P. crispa and P. americana; the pale underside rules out P. atrostriata and P. sorediosa. This leaves only P. poncinsii and P. undulata. Marginal soralia suggest P. undulata.

I have also discovered that tropical regions of northern Mexico (e.g. Sinaloa) have occasional records of many tropical Floridan species, and in this case, it has full desciptions of all of the species mentioned above except P. americana, P. atrostriata. Spore size is similar for all remaining species. However, chemistry and lower cortex color are confirmed. The distinction between P. poncinsii and P. undulata is blurred a little, however.

P. poncinsii P. undulata
habit ~adnate ~loose
lobe tips truncate rounded
lobe width 0.5-2 mm to 2 mm
pruina sometimes always
maculae sometimes never
soralia usually laminal
sometimes marginal
eroded to capitate
sometimes eroded
lower cortex intermediate type indistinct type
spore Pachysporaria-type
19-24.5 × 8.5-10.5 µm
intermediate type
18-27 × 8-11 µm
habitat various bark

Moberg (in Sonoran Flora) emphasizes pruinose tips, undulate sorediate margins and pale lower side of P. undulata, and emphasizes capitate soralia and rock substrate of P. poncinsii (inferred from his comparison with P. caesia, another rock species from southwest with capitate laminal soralia).

Lastly, I believe P. poncinsii is likely to be more rare, as it was found only in one or two locations in Dade County as of the writing of More Florida Lichens, while P. undulata has been recorded many times for nearby Collier and Hillsborough Counties (but notice: not Monroe County for the Keys). The specimen in question is quite common throughout Key Largo, in most habitats I’ve studied: base of rough-barked hardwoods in shady hammocks, on coral blocks around canals, and most especially on buttonwood in bright open coastal scrub.

Created: 2011-01-21 19:29:12 PST (-0800)
Last modified: 2012-01-12 16:29:01 PST (-0800)
Viewed: 178 times, last viewed: 2018-03-12 17:58:34 PDT (-0700)
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