INTRODUCTION

The keys presented on this website are based on recent literature (see list below) and the study of several hundreds of Costarican lichen samples. The descriptions are based on Costa Rican specimens, unless otherwise stated. In that case the descriptions may be incomplete and lack, e.g. some spore characteristics. Hymenium inspersion is then supposed to be absent.
Since the classification of the tropical graphidales is still very poorly known, much uncertainty remains about the delimitation and naming of the taxa used, in particular at species level. It is the hope of the author that the keys will contribute to the development of a better classification of the group.
The current generic delimitation of the Thelotremataceae is particularly unsatisfactory. Therefore the species of this family are treated in a single key. Awaiting a new classification to be proposed soon by Andreas Fritsch, the species are provisionally attributed to the genus where they have been included most recently.
The voucher specimens for the photographs are kept in B, except: leg. Aptroot in herb. Aptroot.
The colours of the pictures may deviate from the natural colours, because they are taken with artificial light, often from several years old herbarium specimens.
These keys are prepared in the frame of the TICOLICHEN project.

References:
Hale, M.E. 1974: Morden-Smithsonian Expedition to Dominica: The lichens (Thelotremataceae). - Smithsonian Contrib. Bot. 16: 1-46.
Hale, M.E. 1978: A revision of the lichen family Thelotremataceae in Panama. - Smithsonian Contrib. Bot. 38: 1-60.
Hale, M.E. 1980: Generic delimitation in the lichen family Thelotremataceae. - Mycotaxon 11: 130-138.
Hale, M.E. 1981: A revision of the lichen family Thelotremataceae in Sri Lanka. - Bull. British Museum (Nat. Hist.), Botany Ser. 8: 227-332.
Kalb, K. & Staiger, B. 2000: Dyplolabia Massalongo, Monographie einer vergessenen Flechtengattung. - Hoppea 61: 409-422.
Kalb, K. 2004: New or otherwise interesting lichens II. Biblioth. Lichenol. 88: 301-329.
Kalb, K., Staiger, B. & Elix, J.A. 2004: A monograph of the lichen genus Diorygma - a first attempt. Symb. Bot. Ups. 34(1): 133-181.
Staiger, B. & Kalb, K. 1999: Acanthothecis and other graphidioid lichens with warty periphysoids or paraphysis-tips. - Mycotaxon 73: 69-134.
Staiger, B. 2002: Die Flechtenfamilie Graphidaceae. Studien in Richtung einer natürlicheren Gliederung. - Bibliotheca Lichenologica, 85, J. Cramer, Berlin, Stuttgart. 526 pp.
Wirth, M. & Hale, M.E. 1963: The lichen family Graphidaceae in Mexico. - Contrib. U.S. Natl. Herb. 36(3): 63-119.
Wirth, M. & Hale, M.E. 1978: Morden-Smithsonian Expedition to Dominica: the lichens (Graphidaceae). - Smithsonian Contributions to Botany 40: 1-64.

Key to the GENERA OF GRAPHIDACEAE / Key to the corticolous SPECIES OF THELOTREMATACEAE in Costa Rica

1A Ascocarps with carbonized parts visible in surface view or in cross section - - - 2
1B Ascocarps without carbonized parts - - - 14

2A Hymenium inspersed with oil-like droplets ca. 1(-5) mu in diam. - - - 3
2B Hymenium clear - - - 8

3A Ascospores colourless, I+ dark violet - - - Graphis
3B Ascospores grey, I+ purplish when young, becoming dark brown with age - - - 4

4A Ascocarps single, unbranched to stellate - - - 5
4B Ascocarps aggregated in pseudostromas, densely branched and/or intertwined, or with fissured disc - - - Sarcographa

5A Ascocarps with thick carbonized lateral excipulum and/or hypothecium - - - 6
5B Ascocarps with thinly carbonized or uncarbonized excipulum - - - 7

6A Carbonisation mainly in lateral exciple; Graphis-like though usually with exposed disc - - - Platygramme
6B Carbonisation mainly in hypothecium; ascocarps raised with thick, pale margins - - - Thecaria

7A Ascocarps with thick, carbonized hypothecium, becoming very prominent with age - - - Leiorreuma
7B Ascocarps with thin, not or slightly carbonized hypothecium, hardly raised above the thallus surface with age - - - Phaeographis

8A (2) Carbonization restricted to a thin layer in the lateral excipulum; ascocarps slit-like, with sunken, usually hidden disc - - - Fissurina
8B Carbonisation throughout the lateral excipulum, sometimes restricted to the apical part, sometimes also in the hypothecium; ascocarps not slit-like but either with firmly closed excipular labiae or with exposed disc - - - 9

9A Ascospores hyaline only when young, later pale grey to grey, often becoming dark brown when old - - - 10
9B Ascospores continuously hyaline - - - 11

10A Ascospores hyaline for much of their development, I+ blueviolet, for a while with very thick outer walls much thicker than the septa, finally pale grey with thin outer walls - - - Aulacographa
10B Ascospores hyaline only when young, soon pale grey to grey, I+ purplish, with outer walls about as thick as septa, becoming dark brown when old - - - Phaeographis

11A Ascospores I-negative - - - 12
11B Ascospores I+ dark violet to dark brown-violet - - - 13

12A Ascospores variously septate; ascocarps C- - - - Carbacanthographis
12B Ascospores 3-septate; ascocarps covered with white, C+ red layer - - - Dyplolabia

13A Disc usually exposed, with brown powdery cover; paraphyses anastomosing, with 2-3 mu thick walls - - - Glyphis
13B Disc usually not visible, without brown powdery cover; paraphyses hardly anastomosing, with thin walls much thinner than lumina - - - Graphis

14A (1) Hymenium inspersed with oil-like droplets ca. 1-5 mu in diam. - - - 15
14B Hymenium clear - - - 17

15A Ascocarp margins thick, uncarbonized; disc invisible - - - "Hemithecium"
15B Ascocarp walls thin, often slightly carbonized, or low; disc exposed - - - 16

16A Ascospores grey, brown when old - - - Phaeographis
16B Ascospores colourless (cf. also Fissurina cf. nitidescens) - - - Anomomorpha

17A Hymenium jelly tough and paraphyses not spreading when a section is squashed; paraphyses with indistinctly delimited, thick, gelatinized walls, only lumina visible in sections; thallus surface dull, without cortex - - - 18
17B Hymenium jelly soft and paraphyses easily spreading when squashing; paraphyses with distinct, thin walls thinner than the lumina; thallus surface mostly slightly shiny and with cortex - - - 19

18A Disc with whitish powdery cover or flesh-coloured to pale brown - - - Diorygma
18B Disc brown or purplish to black - - - "Thalloloma"

19A Paraphyse tips warty to spinulose - - - 20
19B Paraphyse tips smooth - - - 21

20A Ascospores 3-septate - - - Fissurina
20B Ascospores pluriseptate - - - Acanthothecis

21A Ascospores grey, dark brown with age - - - 22
21B Ascospores colourless - - - 23

22A Ascospores with rounded lumina, variously septate, usually with more than 3 septa, over 14 mu long; thallus surface slightly shiny and with cortex - - - Phaeographis
22B Ascospores with cylindrical lumina, 3-septate, up to ca. 13 mu long; thallus surface dull, without cortex - - - Phaeographopsis

23A Ascocarp margins prominent, raised above and often covering the disc, often swollen and grooved; ascospores I+ or I- - - - 24
23B Ascocarp margins low, hardly exceeding the widely visible disc; ascospores I+ violet - - - 25

24A Ascospores I- or I+ pale bluish, often 3-septate - - - Fissurina
24B Ascospores I+ dark violet, always with more than 3 septa - - - Hemithecium

25A Hypothecium becoming thick with age; ascocarps finally strongly raised above the thallus - - - Platythecium
25B Hypothecium thin; ascocarps remaining flush with thallus - - - Thalloloma

The species of Acanthothecis in Costa Rica

1A Ascospores muriform - - - Acanthothecis hololeucoides
1B Ascospores transversely septate - - - Acanthothecis subclavulifera

The species of Anomomorpha in Costa Rica

1A Thallus with schizidia-covered, ca. 1 mm tall and wide warts; ascocarps short and much raised - - - Anomomorpha "tuberculatum"
1B Thallus without prominent warts, without schizidia; ascocarps elongate and initially level with thallus - - - Anomomorpha sordida

The species of Aulacographa in Costa Rica

1A Ascocarps 0.2-0.3 mm wide - - - Aulacographa elegans
1B Ascocarps 0.4-0.6 mm wide - - - Aulacographa "pittierii"

The species of Carbacanthographis in Costa Rica

The species of Dyplolabia in Costa Rica

The species of Glyphis in Costa Rica

1A Ascocarps elongate, Graphis-like with disc reduced to fissure - - - Glyphis substriatula
1B Ascocarps rounded, with one or more brownish, rounded or elongate discs - - - 2

2A Ascocarps with single disc, rounded, apothecium-like - - - Glyphis scyphuliferum
2B Ascocarps with several discs embedded in raised brown stroma-like body - - - Glyphis cicatricosa