The Lesser-known Caloplaca Species

I am putting up the rest of the Caloplacas, for which I have no photographs as a BLOG.

Caloplaca ahtii

Species named after the great Finnish lichenologist Ted Ahti. It is an insignificant little thing which has never been found fertile in the UK. It has an effuse thallus which is bluish grey consisting of squamule like areoles which are to a great or lesser extent, sorediate. It has been found on aspen bark in Central Scotland and is currently considered rare. It could well be under recorded. One for the experts, I think!

Calopla approximata

This species has bright orange apothecia, but is otherwise similar to Caloplaca oasis. It is an extreme rarity occurring on basic rocks on two mountains in the Breadalbane Range in Perthshire.

Caloplaca aractina

This species occurs just above high water mark, especially on serpentine in Western Cornwall where it is locally frequent. I have searched for it several times, but in vane. The thallus looks oily, and is dark grey to black. The apothecia are scattered, and sometimes scarce and are orange brown. Friends tell me that in the right habitat, it is usually quite easy to find. One day perhaps!

Caloplaca arenaria

I have seen this species, but have no photos. The thallus is inconspicuous, and a grey brown colour. The apothecia are generally a dark orange colour with a prominent, paler margoin. As a Caloplaca, it is unusual in occurring on siliceous (more acid, non-calcareous) rock outcrops close to the sea. It has a western distribution in the UK.

Caloplaca atroflava

I believe I was the last to find this species in Britain. In the early days of my interest, I found a Caloplaca on a Fint/chalk nodule in disturbed ground on Butser Hill in Hampshire. It proved to be Caloplaca atroflava when looked at by the experts. This was in 1972, and it has not been seen since. It has a thin, rather dark thallus with bright, rather dark orange fruits. I have looked at specimens in the Natural History Museum which all seem to have darker fruits than the material I found. I think it may be quite variable.

Caloplaca borreri

It has a somewhat scaly thallus and grows on old trees. It has never been found fertile and resembles a corticolous form of Caloplaca chrysodeta. It was found in four localities in eastern England, and has not been seen since the early nineteenth century.

Caloplaca caesiorufella

It has a white thallus, reddish brown fruits with a paler thallus. It occurs on dead wood fencing, and has been found just once in the UK on Shetland.  It could be confused perhaps with Caloplaca asserigena which can also occur on fencing.

Caloplaca cinnamomea

It forms a thin, granular, grey thallus over species of moss. the apothecia are crowded, and are rust red. It is confined to the summit of Ben Lawers in Perthsire.

Caloplaca concilians

This species occurs on  schist rocks in Scotland, and is extremely rare. It has a very dark, areolate thallus, and apothecia which are black when dry, but which go rust red when wetted. It has been found on just four sites both on the coast and in upland sites.

Caloplaca haematites

I kick myself every time I realise I did not bother to photograph this species when I found it on top of a hill on a walnut tree in Corfu. I collected it, and it was confirmed as Caloplaca haematites. It is an attractive species with dark, rust coloured fruits on a scurfy, fairly thick grey thallus. Until very recently, it was thought to be extinct in Britain. It occurs on base rich bark, and especially twigs.

Caloplaca holocarpa

This is the species from which Caloplaca oasis has recently been split. The true Caloplaca holocarpa appears to occur on more acid substrates, and has crowded apothecia. This species, along with the very rare Caloplaca pyracea, confined to aspen bark in Scotland, are little known members of the former Caloplaca holocarpa aggregate. Difficult to say more, as I have no experience of them.

Caloplaca nivalis

As its name suggests, this is a high mountain species confined to Scotland. It has a granular thallus, and has dark, rust coloured fruits and occurs on mosses at high level. It has not been seen recently and is probably extinct.

Caloplaca obliterans

Another species with darkish, rust coloured fruits which arise from a dark grey, insignificant thallus. It occurs in mountainous areas under sheltered overhangs on base rich, vertical rock faces. It is scarce and has been found in Wales and Scotland.

Caloplaca pollinii

This species has a thallus which is pale to dark grey with apothecia which are dark reddish to black. It is almost certainly extinct, having not been seen since the nineteenth century when it was found in Northern England and Scotland. It occurred on more acid barked tree species and was also found on timber. It is possible that more than one species is involved as Scottish material with the black apothecia has been referred to as Caloplaca phaeocarpella.

Caloplaca scopularis

This species resembles Caloplaca arnoldii, but appears more robust and has more spreding marginal lobes. It occurs on siliceous rock which are enriched by bird droppings. It occurs on Islands and the west coast of the UK.

Caloplaca sorediella

In the past, this species was confused with Caloplaca chrysophthalma which it closely resembles. It occurs on the dead stems of Crithmum maritimum, and is rare and appears to have a variety of other habitats including basic barked trees. Currently is is reckoned to be endemic. My guess is that it is a rather ill understood entity.