[ticolichen-Logo] provisional
determination keys
for the Graphidales
of Costa Rica
[bgbm-Logo] [graphidales-Logo] by H. Sipman
BGBM
last updated:
18 August 2008
other webkeys
other Zschackia issues
intro - genera - Acanthothecis - Anomomorpha - Aulacographa - Carbacanthographis - Diorygma - Dyplolabia - Fissurina - Glyphis - Graphis - Hemithecium - Leiorreuma - Phaeographis - Phaeographopsis - Platygramme - Platythecium - Sarcographa - Thalloloma - Thecaria -
corticolous Thelotremataceae

Acanthotrema, Ampliotrema, Chapsa, Gyrotrema, Fibrillithecis, Leptotrema, Leucodecton, Melanotrema, Myriotrema, Ocellularia, Ramonia?, Redingeria, Reimnitzia, Stegobolus, Thelotrema

The species of Fibrillithecis in Costa Rica

Fibrillithecis insignis (Zahlbr.) A.Frisch - Thallus pale greenish to yellowish grey, over 5 cm diam., epiphloeodal, continuous, surface slightly shiny, in part with glistening crystals, with distinct cortex, not oily; medulla indistinct, with cylindrical, 0.5-1 mm long and ca. 0.15 mm wide, uniformly coloured ISIDIA; ascocarps initially immersed in thallus, finally becoming raised and basally constricted, 0.2-0.4 mm wide, with 0.1-0.2 mm wide, round pore, when wide enough showing a whitish to pink disc surrounded by a free, white inner excipulum-ring; hymenium ? mu, clear; spores hyaline, muriform, 8/ascus, I+?, ca. 12 x 7 mu, 4 x 1-2 celled, with thick outer wall; chemistry: psoromic and conpsoromic acids. Specimen studied: Sipman 44331. NOTE: apparently the isidiate morph of M. concretum. Placed by Frisch (2006) in the genus Fibrillithecis but seemingly unrelated to the type species, F. vernicosa (Zahlbr.) A.Frisch and closer to M. concretum.
[F. insignis] [F. insignis]
Costa Rica (Sipman 44331); picture length = 4 mm. Venezuela (Sipman 26631); picture length = 4 mm.

Fibrillithecis pachystoma (Nyl.) INED. - Thallus greenish grey, over 5 cm diam., epiphloeodal, continuous, surface shiny, with distinct, not filmy? cortex, not oily; medulla indistinct, whitish; ascocarps immersed single or in 2s or 3s in raised, 0.7-1.4 mm wide warts with 0.1-0.2 mm wide, round pore with white margin showing the pale disc, with carbonized excipulum, without columella, without externally visible inner excipulum; hymenium ? mu, clear?; spores hyaline, transversely septate, 8/ascus, I+ blue?, ca. 12 x 4 mu, 4 celled; chemistry: psoromic acid. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[F. pachystoma] [F. pachystoma]
Colombia (Lindig s.n. [B]); picture length = 4 mm. Colombia (Lindig 88 [B]); picture length = 4 mm.

Acanthotrema, Ampliotrema, Chapsa, Gyrotrema, Fibrillithecis, Leptotrema, Leucodecton, Melanotrema, Myriotrema, Ocellularia, Ramonia?, Redingeria, Reimnitzia, Stegobolus, Thelotrema

The species of Leptotrema in Costa Rica

Leptotrema wightii (Tayl.) Mll.Arg. - Thallus pale greenish grey, over 6 cm diam., epiphloeodal, continuous, thick and columnar, surface slightly shiny with grainy appearance, with distinct, not filmy cortex, not oily; medulla distinct, whitish with more or less numerous red dots; ascocarps immersed, 0.2-0.3 mm wide with 0.05 mm wide pore, non-carbonized and without columella, without externally visible inner excipulum; hymenium 180-200 mu, clear; spores brown, muriform, 8/ascus, I-negative?, ca. 20-28 x 9-11 mu, 4-6 x 1-3 celled, uniseriate; chemistry: no substance. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. wightii] [M. wightii]
Galapagos Islands (Sipman L-31); picture length = 3.5 mm. Brazil (Malme 2226); picture length = 4 mm.

Acanthotrema, Ampliotrema, Chapsa, Gyrotrema, Fibrillithecis, Leptotrema, Leucodecton, Melanotrema, Myriotrema, Ocellularia, Ramonia?, Redingeria, Reimnitzia, Stegobolus, Thelotrema

The species of Leucodecton in Costa Rica

Leucodecton compunctum (Ach.) A.Massal. - Thallus greenish grey, over 3 cm diam., epiphloeodal, strongly fissured, columnar, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct, whitish; ascocarps immersed or in very slightly raised ca. 0.5 mm wide warts with tiny, 0.05 mm wide, black pore with pale or brownish marginal zone, without externally visible inner excipulum; hymenium ca. 150 mu, clear; spores pale brown, muriform, -8/ascus, juv. I+ pale violet?, ca. 25-32 x 16-18 mu, ca. 6-8 x 3-4 celled; chemistry: stictic, tr. cryptostictic, ?constictic acids, with (12250) or without hypostictic acid and related substance. Specimens studied: Sipman 12250, 37288, 42270a, Aptroot 60360. NOTE: Close to L. reclusum, deviating mainly by the spores, and sometimes by the much more fissured thallus. Nr. 37288 has a thin, hardly fissured thallus. Nr. 60360 lacks the constictic acid-like spot.
[L. compunctum] [L. compunctum]
Costa Rica (Sipman 42270a); picture length = 3.5 mm. Costa Rica (Aptroot 60360); picture length = 3.5 mm.

Leucodecton deceptum (Hale) INED. - Thallus tannish grey, over 3 cm diam., epiphloeodal, continuous to fissured, columnar?, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct, whitish; ascocarps immersed or in very slightly raised ca. 0.4 mm wide warts with tiny, 0.05 mm wide, black pore with darkened marginal zone, without externally visible inner excipulum; hymenium ca. 150 mu, clear; spores pale brown, muriform, 4/ascus, juv. I+ pale violet, ca. 40-80 x 16-30 mu, ca. 16-18 x 5 celled, with thick outer wall; chemistry: stictic, tr. cryptostictic, ?constictic acids (nr. 12081 additionally with hypostictic and ?hyposalazinic acids). Specimen studied: Sipman 12081. NOTE: close to L. reclusum, deviating mainly by the spores, which are 4/ascus.
[L. deceptum]
Costa Rica (Sipman 12081); picture length = 4 mm.

Leucodecton glaucescens (Nyl.) A.Frisch - Thallus pale greenish, over 5 cm diam., epiphloeodal, continuous, surface dull, with distinct, not filmy cortex, not oily; medulla thin, whitish; ascocarps immersed, usually in groups, ca. 0.1-0.2 mm wide with 0.1-0.2 mm wide, round to angular pore with pale rim, without carbonization, with white inner excipulum ring visible through the pore and separated from the thalline margin; hymenium 65-70 mu, clear; spores grey, muriform, 8/ascus, I-, ca. 12-18 x 6-10 mu, 4-6 x 1-3 celled; chemistry: tr. hypostictic, stictic, ?cryptostictic, ?constictic acids. NOTE: Not yet known from Costa Rica, but from El Salvador (in herb. B), on which material the description is based.
[L. glaucescens] [L. glaucescens]
Mexico (Wolf 2207); picture length = 4 mm. El Salvador (Sipman 37890); picture length = 4 mm.

Leucodecton occultum (Eschw.) A.Frisch [Myriotrema occultum (Ach.) Hale] - Thallus pale tannish grey, ca. 3 cm diam., epiphloeodal, strongly finely fissured, columnar, surface dull, finely pitted, with indistinct cortex, not oily; medulla indistinct, whitish; ascocarps immersed or in scarcely raised, ca. 0.3 mm wide warts, with hardly developed thalline margin, with ca. 0.2 mm wide pore showing the pale grey disc surrounded by a white, free inner excipulum; hymenium ca. 90-120 mu, clear; spores pale grey, muriform, -8/ascus, juv. I+ pale violet-brown, ca. 20-30 x 10-14 mu, ca. 6-10 x 3 celled, with thick outer wall; chemistry: norstictic, tr. stictic, tr. connorstictic acids. Specimens studied: Kalb Lich. Neotr. 432, Sipman 52035, 52040a, Aptroot 60844.
[L. occultum] [L. occultum]
Costa Rica (Sipman 52035); picture length = 3.5 mm. Costa Rica (Aptroot 60844); picture length = 3.5 mm.

Leucodecton reclusum (Kremp.) INED. - Thallus greenish grey, over 5 cm diam., epiphloeodal, continuous, somewhat columnar, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct, whitish; ascocarps immersed or in very slightly raised ca. 0.5 mm wide warts with tiny, 0.05 mm wide pore with pale or brownish marginal zone, without externally visible inner excipulum; hymenium ca. 150 mu?, finely guttulate; spores turning pale brown rather late in their development, muriform, 1-2(-4)/ascus, juv. I+ pale violet, ca. (75-)90-140 x 25-35 mu, ca. 40 x 6 celled with ca. 7 primary septa and thick outer wall; chemistry: stictic, tr. cryptostictic, ?constictic acids, with (12245, 12290) or without hypostictic acid and related compounds. Specimens studied: Sipman 12245 (B), 12290 (B), 42271, 42309, Aptroot 60307, 60366. NOTE: The inspersed hymenium and the fact that the spores remain colourless for a long time are not mentioned by Hale (1978). In damaged thalli, in which the top layer of the thallus has been removed, the pores may be wider and surrounded by brown excipular tissue.
[L. reclusum] [L. reclusum]
Costa Rica (Aptroot 60307); picture length = 3.5 mm. Costa Rica (Aptroot 60307), partly eroded with brown excipulum exposed; picture length = 3.5 mm.

Leucodecton sp. 1, "Myriotrema occultum (Eschw.) Hale" [not Leucodecton occultum (Eschw.) A.Frisch] - Thallus pale grey, over 3 cm diam., epiphloeodal, continuous, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed in the thallus or in slightly raised 0.4 mm wide warts, with 0.1-0.2 mm wide pore with margin of same colour as thallus, exposing the free, white inner excipulum and whitish to grey disc; hymenium ca. 70-100 mu, clear; spores grey, muriform, clavate, -8/ascus, I+ violet, ca. 26 x 12 mu, 6 x 1-2 celled, with rounded lumina and thick outer wall; chemistry: norstictic, trace stictic acids. Specimens studied: Sipman 50983B, 51046c. NOTE: determination of the specimen 50983B tentative, assuming that the colourless spores are juvenile and become grey when adult. Deviates from L. fissurinum by non-fissured thallus and different chemistry; resembles M. subcompunctum (Nyl.) Hale, but with larger spores and different thallus structure.
[L. sp. 1] [L. sp. 1]
Costa Rica (Sipman 51046c); picture length = 3.5 mm. Costa Rica (Sipman 51046c); picture length = 3.5 mm.

Leucodecton sp. 2 [Thelotrema cf. microglaenoides Vain.] - Thallus olivaceous grey, over 3 cm diam., epiphloeodal, continuous, surface slightly shiny, with distinct, not filmy cortex, not oily; medulla indistinct, endophloeodal; ascocarps immersed in slightly raised ca. 0.4-0.6 mm wide warts with tiny, 0.05 mm wide, black pore with 0.2-0.3 mm wide, thallus-coloured or, when abraded?, brown or black marginal zone, without externally visible inner excipulum; hymenium ca. 300 mu, clear; spores grey-brown, muriform, 8/ascus, juv. I+ pale violet?, ca. 25-30 x 18-20 mu, ca. 8 x 4-5 celled; chemistry: tr. hypostictic, stictic, tr. cryptostictic, ?constictic acids. Specimens studied: Aptroot 60606, 60611, Sipman51923. NOTE: The material deviates from the description in Hale (1981) by the dark thallus colour and the higher hymenium. In thallus colour it resembles more L. deceptum, which has 4 spores 40-70 x 14-28 mu per ascus.
[T. cf. microglaenoides]
Costa Rica (Sipman 51923); picture length = 3.5 mm.

Acanthotrema, Ampliotrema, Chapsa, Gyrotrema, Fibrillithecis, Leptotrema, Leucodecton, Melanotrema, Myriotrema, Ocellularia, Ramonia?, Redingeria, Reimnitzia, Stegobolus, Thelotrema

The species of Melanotrema in Costa Rica


Melanotrema meiospermum (Nyl.) A.Frisch - Thallus pale ivory grey, over 5 cm diam., epiphloeodal, continuous, surface grainy, shiny, with distinct, not filmy? cortex, not oily; medulla indistinct; ascocarps not common, immersed in the thallus or slightly raised with somewhat slip-like? margin and ca. 0.3-0.5 mm wide, round to elongate pore showing the wide, somewhat actinoid, black columella, with carbonized excipulum, without externally visible inner excipulum; hymenium 90-100 mu, clear; spores grey, transversely septate, 8/ascus, I-, ca. 16-18 x 10 mu, 4 celled; chemistry: no substance. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. meiosperma]
Cuba (Wright, B 40468); picture length = 4 mm.

Melanotrema platystomum (Mont.) A.Frisch [Ocellularia concolor Meyen & Flotow] ? - Thallus greenish grey to pale tannish grey, over 5 cm diam., epi- to endophloeodal, continuous, surface slightly shiny, with distinct cortex, not oily; medulla indistinct; ascocarps immersed in low, 0.4-0.8 mm wide warts with 0.2-0.4 mm wide, rounded or irregularly elongated pores with thallus-coloured or paler margins, with carbonized excipulum and thick, irregular, central carbonized columella, exposed and grey, without externally visible inner excipulum; hymenium ca. 90 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ dark brown-violet, ca. 18-20 x 6-7 mu, 6 celled; chemistry: no substance. Specimens studied: Sipman 48065A, 48065D. NOTE identification uncertain; specimen A has an endophloeiodic thallus, specimen D deviates by an epiphloeiodic thallus. Both deviate from typical M. platystomum by their grey instead of black columella.
[O. concolor] [O. concolor]
Costa Rica (Sipman 48065A); picture length = 3.5 mm. Costa Rica (Sipman 48065D); picture length = 3.5 mm.

Acanthotrema, Ampliotrema, Chapsa, Gyrotrema, Fibrillithecis, Leptotrema, Leucodecton, Melanotrema, Myriotrema, Ocellularia, Ramonia?, Redingeria, Reimnitzia, Stegobolus, Thelotrema

The species of Myriotrema in Costa Rica

Myriotrema "aggregans" INED. - Thallus pale grey, over 3 cm diam., endo(-epi)phloeodal, continuous, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed, ca. 0.1 mm wide, round, with (1-)5-10 grouped, sometimes groups confluent, with brownish disc surrounded by a darker inner excipulum ring; hymenium 60 mu, clear; spores hyaline, muriform, 8/ascus, I+ blue-violet, ca. 18-22 x 8-9 mu, 6 x 2 celled; chemistry: no substance. Specimen studied: Sipman 12351, 51814, 51996. NOTE: an unusual species with its ascocarps in groups and the discs level with the thallus surface.
[M. aggregans]
Costa Rica (Sipman 51996); picture length = 3.5 mm.

Myriotrema album Fe; syn. Ocellularia myriopora (Tuck.) Mll. Arg. - Thallus pale greenish grey, over 5 cm diam., epiphloeodal, continuous, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed with tiny, ca. 0.05-0.1 mm wide, round pore, without externally visible inner excipulum; hymenium ? mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blue?, ca. 16-18 x 5-6 mu, 4-5 celled; chemistry: no substance. NOTE: Recorded by Breuss (2000: 1046, Bosque Esquinas); description after Hale 1978.
[M. album] [M. album]
El Salvador (Sipman 37987); picture length = 4 mm. Cuba (Wright 127); picture length = 4 mm.

Myriotrema clandestinum (Fe) Hale [not Ocellularia clandestina (Ach.) Mll.Arg. sensu A.Frisch] - Thallus pale greenish grey, over 5 cm diam., epiphloeodal, fissured, surface slightly shiny, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed with ca. 0.1-0.2 mm wide, round pore, without externally visible, or occasionally with partly free, visible inner excipulum; hymenium 120 mu, clear; spores hyaline, muriform, 8/ascus, I+ pale blue, ca. 20 x 12 mu, 6 x 3 celled, with thick outer wall; chemistry: psoromic acid. Specimens studied: Sipman 41567, 12256 (U).
[M. clandestinum] [M. clandestinum]
Costa Rica (Sipman 41567); picture length = 3.5 mm. Costa Rica (Sipman 12256); picture length = 3.5 mm.

Myriotrema concretum (Fe) Hale - Thallus pale greenish to yellowish grey, over 5 cm diam., epiphloeodal, continuous or fissured, surface slightly shiny, partly with glistening crystals, with distinct cortex, not oily; medulla indistinct; ascocarps initially immersed in thallus, finally becoming raised and basally constricted, 0.2-0.5 mm wide, with 0.1-0.3 mm wide, round pore, when wide enough showing a whitish to pink disc surrounded by a free, white inner excipulum-ring; hymenium ca. 80 mu, clear; spores hyaline, muriform, -8/ascus, I+ blue or violet, ca. 13-15 x 7 mu, 4 x 1-2 celled, with thick outer wall; chemistry: psoromic and conpsoromic acids. Specimens studied: Sipman 20776, 20805, 46562. NOTE: the isidiate form seems to be Fibrillithecis insignis.
[M. concretum] [M. concretum]
Costa Rica (Sipman 46562); picture length = 4 mm. Costa Rica (Sipman 20805); picture length = 4 mm.

Myriotrema congestum (Hale) Hale - Thallus pale grey, over 5 cm diam., epiphloeodal, continuous or fissured, surface slightly shiny, with distinct cortex, not oily; medulla indistinct; ascocarps initially immersed in thallus, finally becoming raised and basally constricted, 0.2-0.4 mm wide, with 0.1-0.2 mm wide, round pore, when wide enough showing a whitish to pink disc surrounded by a free, white inner excipulum-ring?; hymenium ca. ? mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blue?, ca. 18 x 8 mu, 4 celled; chemistry: hypoprotocetraric acid. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. congestum] [M. congestum]
Ecuador (Sipman 51327); picture length = 4 mm. Venezuela (Sipman 26479); picture length = 4 mm.

Myriotrema costaricense (Mll. Arg.) Hale - Thallus pale greenish grey, over 5 cm diam., epiphloeodal, continuous or fissured, surface slightly shiny, with distinct , slightly filmy cortex, not oily; medulla thin, white; ascocarps immersed in thallus or in low, 0.4-0.5 mm wide warts with 0.1-0.5 mm wide, round to edgy pore showing a pale grey disc occasionally with whitish columellae, surrounded by a partly free, white inner excipulum-ring; hymenium ca. 75 mu, clear; spores hyaline, transversely septate, -8/ascus, I+ pale blue, ca. 14-18 x 5 mu, 4-6 celled, with equally thickened septa and wall; chemistry: psoromic acid. Specimen studied: Aptroot 60863.
[M. costaricense]
Costa Rica (Aptroot 60863); picture length = 3.5 mm.

Myriotrema dactyliferum (Hale) Hale - Thallus greenish grey, over 5 cm diam., epiphloeodal, continuous, surface dull, finely granulose, with distinct cortex, not oily; medulla indistinct; with cylindrical, to 0.5 mm tall ISIDIA; ascocarps immersed in thallus or finally slightly raised, 0.1-0.15 mm wide, with 0.05 mm wide, round pore with white-pruinose margin, without externally visible inner excipulum; hymenium 60-90 mu, clear; spores hyaline, transversely septate, 8/ascus, I-neg., ca. 12-16 x 5-6 mu, 5-8 celled; chemistry: stictic, constictic acids. NOTE: Description after Hale (1978) with additions from the specimens illustrated. Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. dactyliferum] [M. dactyliferum]
Guyana (Sipman 19433); picture length = 4 mm. ?, Guyana (Sipman 18852); picture length = 4 mm.

Myriotrema "diplocolumnaris" INED. - Thallus greenish grey, over 10 cm diam., epiphloeodal, continuous, columnar, surface dull, with indistinct cortex, not oily; medulla distinct, whitish; ascocarps immersed, with 0.05-0.2 mm wide, round pore, sometimes showing a slender columella, not carbonized, without externally visible inner excipulum; hymenium 240 mu, clear; spores brown, muriform, 8/ascus, juv. I+ violet, ca. 20 x 10 mu, 6 x 2 celled, with thick outer wall; chemistry: psoromic acid. Specimen studied: Sipman 41966.
in prep.

Myriotrema glaucophaenum (Kremp.) Hale - Thallus greenish grey, over 5 cm diam., epiphloeodal, continuous, surface slightly shiny, with distinct cortex, not oily; medulla thin, whitish; ascocarps immersed in hardly raised, 0.2-0.3 mm wide warts with 0.1 mm wide pore with pale margin not showing the disc, without carbonisation, without externally visible inner excipulum; hymenium ca. 180 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ dark violet, ca. 28-35 x 10-12 mu, 10-12 celled; chemistry: psoromic acid. Specimen studied: Sipman 47816C. NOTE: Nr. 47816C looks much like fig. 6b (Hale 1978) but deviates by its large spores.
[O. glaucophaena]
Costa Rica (Sipman 47816C); picture length = 3.5 mm.

Myriotrema glauculum (Nyl.) Hale - Thallus pale grey, over 5 cm diam., epiphloeodal, continuous or fissured, surface dull, with distinct, not filmy cortex, not oily; medulla distinct; ascocarps immersed, ca. 0.1-0.2 mm wide with 0.1 mm wide, round pore with white rim, without carbonization, with white inner excipulum ring visible through the pore and separated from the thalline margin; hymenium 70 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blueish, ca. 10-14 x 5-6 mu, 3-4 celled; chemistry: hypoprotocetraric acid and lichexanthone. NOTE: similar to M. microporellum, but with dull white thallus and distinctly free inner excipulum. Description after Hale (1978) with additions from the illustrated specimens. Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. glauculum] [M. glauculum]
Guyana (Sipman 18953); picture length = 4 mm. Guyana (Sipman 18953); picture length = 4 mm.
[M. glauculum]
Guyana (Sipman 18069b); picture length = 4 mm.

Myriotrema hartii (Mll. Arg.) Hale - Thallus pale greenish to yellowish grey, over 5 cm diam., epiphloeodal, fissured, surface slightly shiny, with distinct cortex, not oily; medulla indistinct, with cylindrical, 0.5-1 mm long and 0.25 mm wide, dark-tipped ISIDIA; ascocarps (not seen in R material, after Hale 1981) initially immersed in thallus, finally becoming raised and basally constricted, 0.2-0.3 mm wide, with 0.1-0.15 mm wide, round pore, when wide enough showing a whitish to pink disc surrounded by a free, white inner excipulum-ring; hymenium ca. 40 mu, clear; spores hyaline, muriform, 8/ascus, I+?, ca. 13-15 x 6 mu, 4 x1-2 celled; chemistry: psoromic and conpsoromic acids. Specimen studied: Campos 80. NOTE: seemingly another isidiate form of M. concretum, with thicker, more erect isidia than Fibrillithecis insignis. In the absence of ascocarps the identification is provisional.
[M. hartii] [M. hartii]
Costa Rica (Campos 80); picture length = 4 mm. El Salvador (Sipman 37548); picture length = 4 mm.

Myriotrema laeviusculum (Nyl.) Hale - Thallus greenish grey, with minutely warty surface, over 5 cm diam., epiphloeodal, continuous, surface dull, with distinct cortex, not oily, somewhat columnar; medulla indistinct; ascocarps immersed in the thallus, ca 0.2 mm wide with 0.1 mm wide, white-rimmed pore often showing a tall, white-capped columella, impressed or not, without externally visible inner excipulum; hymenium ca. 110-240 mu, clear; spores brown, muriform, 8/ascus, juv. I+ violet, ca. 18-20 x 10 mu, 6 x 2-3 celled; chemistry: protocetraric acid. Specimen studied: Sipman 41966, 51636.
[M. laeviusculum] [M. laeviusculum]
Costa Rica (Sipman 41966); picture length = 3.5 mm. Costa Rica (Sipman 51636); picture length = 3.5 mm.

Myriotrema microporellum (Nyl.) Hale; syn. Ocellularia plurifaria (Nyl.) Mll.Arg. - Thallus pale greenish grey, over 5 cm diam., epiphloeodal, continuous, surface shiny, with distinct, not filmy? cortex, not oily; medulla distinct; ascocarps immersed, ca. 0.1-0.2 mm wide with 0.1 mm wide, round pore with white rim, without carbonization, pale tan disc visible, rarely with white inner excipulum ring visible through the pore and separated from the thalline margin; hymenium ? mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blue?, ca. 12-24 x 5-8 mu, 4-6 celled; chemistry: hypoprotocetraric acid. NOTE: similar to M. glauculum, but with glossy greenish thallus. Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. microporellum] [M. microporellum]
Cuba (Wright 126); picture length = 4 mm. Brazil (Sipman 13979); picture length = 4 mm.

Myriotrema myriocarpum (Fe) Hale ? - Thallus greenish grey, over 5 cm diam., epiphloeodal, continuous, surface shiny, with distinct, almost filmy cortex, not oily; medulla pale brownish; ascocarps immersed in the thallus or in very slightly raised, ca. 0.3 mm wide, very low warts with ca. 01-0.15 mm wide pore with whitish inner rim showing the free, white inner excipulum and the pinkish disc; hymenium ca. 120 mu, clear; spores hyaline, muriform, 8/ascus, I-negative, ca. 25 x 12 mu, 10 x 4 celled; chemistry: stictic acid. Specimen studied: Sipman 47892. NOTE: The material resembles Leucodecton occultum from which it differs by its colourless, I-negative spores. The spores have very small cells, as in Thelotrema glaucopallens, from which it differs by its wider pores showing the disc with separated inner excipulum. The thallus of the available material is not fissured contrary to the indication of Hale (1978).
[M. myriocarpum]
Costa Rica (Sipman 37294); picture length = 4 mm.

Myriotrema myrioporoides (Mll. Arg.) Hale - Thallus pale greenish to yellowish grey, over 5 cm diam., epiphloeodal, continuous, surface slightly shiny, with distinct, not filmy cortex, not oily; medulla indistinct; ascocarps immersed in thallus or in low, ca. 0.2-0.4 mm wide warts, with ca. 0.1-0.2 mm wide, round pore often showing the pinkish disc surrounded by the white, free inner excipulum or with white columellae; hymenium 60-75 mu, clear; spores hyaline, muriform, 8/ascus, I+ blue-violet/dark violet, ca. 12-20 x 7 mu, 4-6 x 1-2 celled; chemistry: lichexanthone (in 51792), hypoprotocetraric acid and associates. Specimens studied: Sipman 12256, 51792.
[M. myrioporoides] [M. myrioporoides]
Costa Rica (Sipman 51792); picture length = 3.5 mm. Costa Rica (Sipman 51636); picture length = 3.5 mm.
[M. myrioporoides] [M. myrioporoides]
Costa Rica (Aptroot 60611); picture length = 3.5 mm. Costa Rica (Sipman 12256); picture length = 3.5 mm.

Myriotrema myriotremoides (Nyl.) Hale - Thallus pale greenish or blue-greenish grey, often with paler spots around groups of ascocarps, over 5 cm diam., epiphloeodal, continuous, surface dull, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed, with 0.05 mm wide, round pore with whitish rim, sometimes grouped in lines, without externally visible inner excipulum; hymenium 50 mu, clear; spores hyaline, transversely septate, -8/ascus, I+ violet, ca. 8 x 3 mu, 3-4 celled; chemistry: psoromic acid. Specimen studied: Sipman 42378.
[M. myriotremoides]
Costa Rica (Sipman 42378); picture length = 3.5 mm.

Myriotrema neofrondosum Sipman - Thallus pale greenish grey, often over 10 cm diam., epiphloeodal, continuous or reticulately cracked, surface slightly shiny, with distinct cortex, not oily; medulla indistinct; ascocarps immersed in thallus, c. 0.2 mm wide, with 0.1-0.2 mm wide, round pore, when wide enough showing a whitish to pink disc without free, white inner excipulum-ring; hymenium 60-70 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blueish, ca. 10-15 x 6-7 mu, 4 celled; chemistry: hypoprotocetraric acid, occasionally with lichexanthone (after Sipman (1992). NOTE: Communicated by B. Emmerer (Graz).
[M. neofrondosum] [M. neofrondosum]
Venezuela (Galiz 45b), vegetative propagules; picture length = 4 mm. Venezuela (Sipman 26855), ascocarps; picture length = 4 mm.
[M. neofrondosum]
Venezuela (Sipman 26855), vegetative propagules and sterile pores; picture length = 4 mm.

Myriotrema "nicoyense" INED. - Thallus whitish grey, over 5 cm diam., epiphloeodal, irregularly fissured, surface slightly shiny, with distinct cortex, not oily; medulla whitish; ascocarps immersed in the thallus or in slightly raised, 0.5 mm wide, warts with ca. 0.2-0.4 mm wide pore with hardly developed margin, the white disc fully exposed and surrounded by a free, white inner excipulum; hymenium ca. 150 mu, clear; spores hyaline, muriform, 8/ascus, I-negative, ca. 45 x 14 mu, ca. 16 x 4 celled, with thin septa; chemistry: psoromic acid. Specimen studied: Aptroot 60884. NOTE: The spores remind of Chroodiscus, but the free inner excipulum and absence of marginal slips are more like Myriotrema or Thelotrema.
[M. nicoyense]
Costa Rica (Aptroot 60884); picture length = 3.5 mm.

Myriotrema norsticticum (Hale) Hale - Thallus pale grey, over 5 cm diam., epiphloeodal, continuous, surface slightly shiny?, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed with tiny, ca. 0.05 mm wide, round, white-rimmed pore, without externally visible inner excipulum; hymenium ? mu, clear; spores hyaline, muriform, 8/ascus, I+ blue?, ca. 12-14 x 6-8 mu, 4 x 1-2 celled; chemistry: norstictic acid. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
[M. norsticticum]
Guyana (Sipman 18457); with sterile ascocarps; picture length = 4 mm.

Myriotrema olivaceum Fe - Thallus pale greenish grey, over 5 cm diam., epiphloeodal, continuous or fissured, surface slightly shiny, with indistinct cortex, not oily; medulla distinct, whitish; ascocarps immersed, 0.15-0.3 mm wide, without columella or carbonisation, with ca. 0.1 mm wide, round, more or less sunken pore, without externally visible inner excipulum; hymenium 60-80 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blueish, ca. 6-12 x 4-7 mu, 4 celled; chemistry: olivacea unknown. Specimen studied: Sipman 12238 (U).
[M. olivaceum]
Costa Rica (Sipman 12238); picture length = 3.5 mm.

Myriotrema "pseudopycnoporellum" INED. - Thallus greenish grey, over 2 cm diam., epiphloeodal, continuous, surface shiny, with distinct cortex, not oily; medulla indistinct, whitish; ascocarps immersed in the thallus, with 0.05 mm wide, dark pore not showing any externally visible inner excipulum or disc; hymenium 60 mu, clear; spores hyaline, muriform, 8/ascus, I+ blue-violet, ca. 18-25 x 8 mu, 6 x 1-2 celled, ; chemistry: no substance. Specimen studied: Sipman 51104F. NOTE: deviates from M. pycnoporellum (Nyl.) Hale by a greenish, much more extended, instead of a pale brownish, few cm wide thallus.
[M. pseudopycnoporellum]
Costa Rica (Sipman 51104F); picture length = 3.5 mm.

Myriotrema pulverulentum (Hale) Hale - Thallus pale green, over 5 cm diam., epiphloeodal, fissured, verruculose or subgranular, surface dull, with distinct, not filmy cortex, not oily, with irregularly distributed granular ISIDIA or fine, course-grained SORALIA; medulla indistinct, whitish; ascocarps immersed in raised, 0.4-1.0 mm wide, sorediascent warts with 0.1 mm wide, round pore, not carbonized and without columella, without externally visible inner excipulum; hymenium 60-70 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blue?, ca. 18-24 x 6-10 mu, 6-7 celled; chemistry: psoromic acid. NOTE: Known from Panama, description after Hale 1978.
in prep.

Myriotrema terebratulum (Nyl.) Hale? - Thallus pale greenish grey, over 5 cm diam., epiphloeodal, with scattered fissures, surface slightly shiny, with indistinct cortex, not oily; medulla distinct, white; ascocarps immersed in the thallus, with ca. 0.05 mm wide, sunken pore with pale margin, with invisible disc, without externally visible inner excipulum; hymenium 60-80 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ brown-violet, ca. 8 x 2.5-3 mu, 4 celled; chemistry: psoromic acid. Specimens studied: Sipman 48062C, 48063A. NOTE: The specimens seem to deviate by a less developed cortex , weakly fissured thallus and smaller spores; the spores suggest a close affinity to Ocellularia.
[M. terebratulum] [M. terebratulum]
Costa Rica (Sipman 48062C); picture length = 3.5 mm. Costa Rica (Sipman 48063A); picture length = 3.5 mm.

Myriotrema trypaneoides (Nyl.) Hale [?] - Thallus greenish grey, over 3 cm diam., epiphloeodal, continuous, surface shiny, with distinct, somewhat filmy cortex, not oily; medulla thin, white; ascocarps immersed, ca. 0.1 mm wide, with tiny, ca. 0.05 mm wide, black pore surrounded by a usually contrastingly pale, or thallus-coloured marginal zone, without externally visible inner excipulum; hymenium ca. 100 mu, clear (in 37286 fine-inspersed); spores pale brown, muriform, 8/ascus, oval, I-negative?, ca. 28-30 x 12 mu, ca. 10 x 3 celled; chemistry: stictic, ?constictic acids. Specimens studied: Sipman 42313, 37286.
[M. trypaneoides] [M. trypaneoides]
Costa Rica (Sipman 42313); picture length = 3.5 mm. Costa Rica (Sipman 12113); picture length = 3.5 mm.
[M. trypaneoides] [M. trypaneoides]
Costa Rica (Sipman 12084); picture length = 3.5 mm. Costa Rica (Sipman 12084); picture length = 3.5 mm.

Myriotrema uniseptatum (Hale) Hale - Thallus whitish, over 5 cm diam., epiphloeodal, continuous, surface dull, finely verruculose, with distinct, not filmy cortex, not oily; medulla distinct?; ascocarps immersed, ca. 0.1-0.2 mm wide with 0.07 mm wide, round pore with white rim, without carbonization or columella, with disc not visible through the pore, without externally visible inner excipulum; hymenium 45-40 mu, clear; spores hyaline, transversely septate, 8/ascus, I+ blue?, ca. 16 x 3-4 mu, 2(-3) celled; chemistry: psoromic acid. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
in prep.

Myriotrema urceolare (Ach.) Hale - Thallus green-grey, often over 10 cm diam., epiphloeodal, continuous, surface dull, with indistinct cortex, not oily; medulla indistinct; ascocarps immersed in low, 0.5-0.8 mm wide warts with initially 0.1-0.2 mm wide, round, pale pore, later to 0.5 mm wide and showing the grey disc sometimes with pale, non-carbonized columellae, without externally visible inner excipulum, not carbonized; hymenium ca. 150-180 mu, clear; spores grey-brown, muriform, clavate, -8/ascus, I-negative (?), 25-35 x 12-13 mu, 6-8 x 2-3 celled, full-grown with rounded lumina and thicker outer wall; chemistry: no substance. Specimens studied: Sipman 47810C, 47820D, 44328. NOTE: The isentification is uncertain because the material is very similar to O. bahiana, differing by the absence of protocetraric acid, and may be a strain of that species.
[M. urceolare] [M. urceolare]
Costa Rica (Sipman 47810C); picture length = 3.5 mm. Costa Rica (Sipman 47818E); picture length = 3.5 mm.

Myriotrema vulcani (Hale) Hale ? - Thallus blue-greenish, over 5 cm diam., epiphloeodal, continuous or finally fissured, surface dull?, with distinct?, not filmy cortex, not oily; medulla distinct?; ascocarps immersed or semi-emersed, ca. 0.5-0.7 mm wide with 0.2-0.3 mm wide, round or elongate pore with white rim, without carbonization or columella, without externally visible inner excipulum; hymenium 60-90 mu, clear; spores grey, transversely septate, 8/ascus, I-, ca. 10-12 x 4-5 mu, 2-3 celled; chemistry: no substance. NOTE: Description after Hale (1978). Not yet known from Costa Rica, but reported from Panama (Hale 1978).
in prep.

Acanthotrema, Ampliotrema, Chapsa, Gyrotrema, Fibrillithecis, Leptotrema, Leucodecton, Melanotrema, Myriotrema, Ocellularia, Ramonia?, Rechingeria, Reimnitzia, Stegobolus Thelotrema