Malmidea Pallidoatlantica

''Malmidea'' is a genus of crustose lichens and the type genus of the family Malmideaceae. It was established in 2011 to contain a phylogenetically distinct group of species formerly placed in the genus ''Malcolmiella''. ''Malmidea'' comprises more than 50 mostly tropical species that grow on bark, although a few grow on leaves.

Taxonomy

Both the family Malmideaceae and the genus ''Malmidea'' were created in 2011 to accommodate a group of species, formerly placed in genus ''Malcolmiella'' (family Pilocarpaceae), that molecular phylogenetics showed to be a distinct lineage and worthy of recognition at the family level. Klaus Kalb, Eimy Rivas Plata, and H. Thorsten Lumbsch originally placed 37 species in the genus – 5 new species and 32 new combinations. Many additional species have since been transferred to ''Malmidea'' from other genera, or described as new.

The generic name ''Malmidea'' honours Swedish botanist Gustaf Oskar Andersson Malme (1864–1937).

Description

The thallus of ''Malmidea'' lichens grow on bark ( corticolous) or on leaves (foliicolous). The form of the thallus is like a crust, ranging in surface texture from smooth to verrucose (studded with wartlike protuberances), granulose (covered with small grains) or pustulate (covered with pustules). These variously shaped surface bumps are often formed by goniocysts (spherical aggregations of photobiont cells surrounded by short-celled hyphae) that develop on a whitish fibrous underlying prothallus. The photobiont partner of ''Malmidea'' is a member of Chlorococcaceae, a family of green algae.

''Malmidea'' apothecia are sessile, with a more or less rounded shape, and have a distinct margin. They have a biatorine structure, meaning that they have only a pale, not blackened proper margin and always lack a margin on the thallus. The excipulum is usually paraplectenchymatous (a cell arrangement where the hyphae are oriented in all directions), made of radiating hyphae, partly with medullary layer or chambers composed of loosely arranged, periclinal hyphae (i.e. lined up in parallel adjacent to another layer of hyphae) with constricted septa and incrusted with hydrophobic granules. The hypothecium (the layer of hyphal tissue immediately beneath the hymenium) is prosoplectenchymatous (a cell arrangement where the hyphae are all oriented in one direction), and translucent to dark brown. Asci are club-shaped, lacking a distinct tubular structure in the tholus that is characteristic of family Pilocarpaceae. Ascospores usually number 4 to 8 per ascus, and are colourless, ellipsoid, non- septate, and usually filled with oblong crystals. The spore walls are evenly thickened or thickened at the ends, and halonate (having a transparent outer layer). Conidia are threadlike and curved, measuring 17–25 by 0.8 μm.

Secondary chemicals associated with ''Malmidea'' include atranorin, sometimes norsolorinic acid (as in '' M. piperis''), anthraquinones, biphenyls and many unknown xantholepinones.

Species

, ''Malmidea'' contains an estimated 52 species, although more are expected to be transferred into the genus from tropical species of '' Lecidea''. ''Malmidea'' mostly occurs in tropical rainforests. Eleven new ''Malmidea'' species were reported from Brazil and Venezuela in 2021.

*'' Malmidea albomarginata'' – Venezuela
*''Malmidea allobakeri'' – Brazil
*'' Malmidea allopapillosa'' – Venezuela
*''Malmidea amazonica''
*'' Malmidea atlantica''
*'' Malmidea atlanticoides'' – Brazil
*''Malmidea attenboroughii'' – Bolivia
*'' Malmidea aurigera''
*'' Malmidea bacidinoides''
*''Malmidea badimioides''
*'' Malmidea bakeri'' – Asia
*'' Malmidea ceylanica''
*''Malmidea chrysostigma'' – Asia
*''Malmidea cineracea'' – Nicaragua
*'' Malmidea cinereonigrella''
*'' Malmidea coralliformis'' – Thailand
*'' Malmidea corallophora'' – Philippines
*''Malmidea duplomarginata''
*''Malmidea eeuuae'' – Thailand
*'' Malmidea fellhaneroides''
*''Malmidea fenicis''
*'' Malmidea flavopustulosa''
*'' Malmidea floridensis'' –
*''Malmidea fulva''
*'' Malmidea furfurosa''
*''Malmidea fuscella''
*''Malmidea granifera''
*'' Malmidea gyalectoides''
*''Malmidea gymnopiperis''
*'' Malmidea hechicerae'' – Venezuela
*''Malmidea hernandeziana'' – Venezuela
*''Malmidea hypomelaena''
*'' Malmidea incrassata'' – Brazil
*''Malmidea indica''
*''Malmidea inflata'' – Thailand
*''Malmidea isidiifera'' – Brazil; Venezuela
*'' Malmidea leptoloma''
*'' Malmidea leucogranifera''
*'' Malmidea leucopiperis'' – Brazil; Venezuela
*''Malmidea nigromarginata'' – Nicaragua
*'' Malmidea pallidoatlantica'' – Brazil
*'' Malmidea papillosa'' – Sri Lanka
*'' Malmidea perisidiata''
*'' Malmidea perplexa'' – Brazil; Thailand
*''Malmidea piae'' – Thailand
*'' Malmidea piperina''
*''Malmidea piperis''
*'' Malmidea plicata'' – Sri Lanka
*'' Malmidea polisensis''
*''Malmidea polycampia''
*''Malmidea psychotrioides''
*'' Malmidea reunionis'' – Réunion
*'' Malmidea rhodopsis''
*''Malmidea rhodopisoides'' – Brazil
*''Malmidea sanguineostigma'' – Sri Lanka
*''Malmidea sorsogona''
*''Malmidea subaurigera'' – Asia
*'' Malmidea subcinerea'' – Venezuela
*'' Malmidea subgranifera''
*'' Malmidea sulphureosorediata'' – Brazil
*''Malmidea taytayensis''
*''Malmidea trailiana''
*'' Malmidea tratiana'' – Thailand
*''Malmidea variabilis'' – Thailand
*'' Malmidea vinosa''
*''Malmidea volcaniana'' – Brazil; Venezuela

References

{{Taxonbar, from=Q17389018

Malmideaceae
Lichen genera
Lecanorales genera
Taxa described in 2011
Taxa named by Helge Thorsten Lumbsch
Taxa named by Klaus Kalb