BGBM: lichens, keys, CR Hemithecium

The species of Hemithecium in Costa Rica

1A Hymenium clear; ascospores colourless (Hemithecium s. str.) - - - 2
1B Hymenium inspersed with ca. 1-4 mu wide oil-like droplets; ascospores grey, darkbrown when old (subg. Leucogramma) - - - Hemithecium chrysenteron

2A Ascospores transversely septate, ca. 30-60 x 8 mu - - - 3
2B Ascospores muriform - - - 4

3A Ascocarp labiae closed, no disc visible - - - Hemithecium laubertianum
3B Ascocarp labiae open, showing a grey-brown disc - - - Hemithecium "amplior"

4A Ascospores 1/ascus - - - Hemithecium chlorocarpum
4B Ascospores more than 1/ascus - - - 5

5A Ascospores under 50 mu long, 8/ascus; ascocarp margins hardly raised above the thallus - - - Hemithecium balbisii
5B Ascospores over 50 mu long, ca. 4/ascus; ascocarp margins distinctly raised above the thallus - - - Hemithecium rufopallidum

Hemithecium "amplior" - Ascocarps 0.3-0.4 mm wide, much winding or shorter, more or less stellate-branched; margins raised, concolorous with the thallus outside, whitish, somewhat grooved, showing the grey-brown disc; hymenium ca. 100 mu, clear; ascospores 8/ascus, colourless, transversely septate, ca. 37 x 8 mu, ca.10 celled. Specimen studied: Sipman 53335. NOTE: The specimen does not fit completely the genus as defined by Staiger (2002) because of the exposed disc.


Costa Rica (Sipman 53335); picture length = 7 mm.

Hemithecium balbisii (Fée) Trevis. - Ascocarps much branched and winding, immersed; margins scarcely raised, concolorous with the thallus outside, whitish at the rim and brownish inside, closed; hymenium ca. 100 mu, clear; ascospores 8/ascus, colourless, muriform, ca. 30 x 15 mu, ca. 12 x 5 cells. Specimen studied: Sipman 48369C.


Costa Rica (Sipman 48369C); picture length = 7 mm.

Hemithecium chlorocarpum (Fée) Trevis. - Ascocarps much branched and winding, immersed; margins scarcely raised, concolorous with the thallus outside, dark brownish inside, closed; hymenium ca. 150-180 mu, clear; ascospores 1/ascus, colourless, muriform, ca. 90 x 35 mu, ca. 20 x 10 cells. Specimen studied: Sipman 51835.


Costa Rica (Sipman 51835); picture length = 7 mm.

Hemithecium chrysenteron (Mont.) Trevis. (= Phaeographina chrysentera (Mont.) Müll. Arg.) - Ascocarps elongate, raised, 0.5-0.7 mm wide; margins prominent, white, sulcate, mostly closed; hymenium ca. 180 mu, inspersed; ascospores 8/ascus, grey, muriform, ca. 50-60 x 15 mu, ca. 14 x 4 cells. Specimens studied: Sipman 48110A, 51074B, 12149. NOTE: Also reported by Staiger (2002).


Costa Rica (Sipman 51074B); picture length = 7 mm.	Costa Rica (Sipman 48110A); picture length = 7 mm.

Hemithecium laubertianum (Fée) Staiger - Ascocarps 0.3-0.4 mm wide, much winding, immersed; margins raised, concolorous with the thallus outside, white to brownish on the rim and inside, closed; hymenium 60-100 mu, clear; ascospores 8/ascus, colourless, transversely septate, 25-50 x 8-14 mu, ca.7-12 celled. Specimens studied: Sipman 51038, 52048. NOTE: The identification is uncertain because the thick outer spore walls indicated by Staiger (2002) were not observed.


Costa Rica (Sipman 51045E); picture length = 7 mm.	Costa Rica (Sipman 50981A); picture length = 7 mm.

Costa Rica (Sipman 50981A); picture length = 7 mm.	Costa Rica (Sipman 52048); picture length = 7 mm.

Hemithecium rufopallidum (Vain.) Staiger - Ascocarps 0.3-0.4 mm wide, moderately branched and winding, immersed; margins raised above the thallus, concolorous with the thallus outside, pale orange inside, closed; hymenium ca. 130-150 mu, clear; ascospores 2-6/ascus, colourless, muriform, ca. 50-90 x 17-30 mu, 13-20 x 5-7 cells. Specimen studied: Sipman 48020C.


Costa Rica (Sipman 48020C); picture length = 7 mm.