Lichens (1985) - Flora of New Zealand Lichens
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Bacidia De Not.

BACIDIA de Not., 1846

Thallus heteromerous, crustose to ± squamulose, microphylline or effuse, with or without a pale or dark marginal prothallus. Photobiont green ? Trebouxia. Apothecia sessile, rounded or ± irregular, lecideine, excipulum well developed of para- or prosoplectenchymatous tissue. Paraphyses simple or branched. Ascus thick-walled, 8-spored. Ascospores long, filiform, acicular to ellipsoid, straight or curved, 2- or more septate, thin-walled, colourless. Pycnidia sessile, ± globose to urceolate. Conidiophores simple with apically formed conidia. Conidia simple or septate, filiform to ellipsoid or oblong, bacillar or acicular.

Key

1
Saxicolous
2
Corticolous or foliicolous
6
2
On soil or among mosses
3
On rock
4
3
Thallus granular-papillate, white, spores 5-7 septate
Thallus filmy, olivaceous, spores 3-septate
4
Apothecia pale orange-brown or red-brown
Apothecia black or brown-black
5
5
Apothecia black, spores 4-5-septate, 32×11 µm
Apothecia brown-black, spores 3-septate 14-18 × 4-6 µm
6
Foliicolous
7
Corticolous
8
7
Apothecia orange-yellow, spores 3-7-septate, 20-40 × 1.5-2 µm
Apothecia brown, spores 3-5-septate, 12-18 × 3-4 µm
8
Apothecia black
9
Apothecia grey, yellow, pink, red-brown or brown
11
9
Spores spiral in ascus, 10-18-septate
Spores straight, 3-9-septate
10
10
Thallus dark olivaceous, apothecia 0.05-0.02 mm diam., spores 30-38 × 3-3.5 µm
Thallus grey-white to glaucous-grey, apothecia 0.2-1.5 mm diam., spores 35-65 × 4-5 µm
11
Apothecia grey-pruinose
Apothecia epruinose
12
12
Apothecia yellow or orange-yellow
13
Apothecia brown, red-brown or pinkish
15
13
Spores spiral
Spores straight or slightly curved
14
14
Spores 3-septate, 8-16 × 6-9 µm
Spores 3-6(-8)-septate, 24-34(-39) × 1.7-2.5(-3.5) µm
15
Apothecia sessile to subpedicellate
16
Apothecia ± innate, never subpedicellate
18
16
Apothecia pinkish or orange-brown
Apothecia brown or red-brown
17
17
Apothecia brown, distinctly subpedicellate, spores 30-75-septate
Apothecia red-brown, sessile, spores 7-16-septate
18
Thallus ± isidiate, spores 3-7-septate, 34-41 × 1.7-2.5 µm
Thallus verrucose, glebose, not isidiate, spores 7-18-septate, 70-87 × 3.2-3.5 µm

Bacidia is a heterogeneous assemblage of c. 400 species of wide distribution. According to Santesson [ Symb. bot. upsal. 12: 436-440 (1952)] the currently accepted delimitation of the genus, that of Zahlbruckner [ In Engler and Prantl, Die Natürlich. Pflanzenfam. I(1): 135 (1905)] viz., species in the Lecideaceae having a crustose thallus and colourless, thinwalled spores with two or more transverse septa, is not a natural grouping. Relationships with genera such as Catillaria, Catinaria, Lopadium, Scoliciosporum and Toninia remain to be clarified. Species of Bacidia may be foliicolous, corticolous or saxicolous and taxa with each of these habits are known in New Zealand. Lamb [ Rhodora 56: 121-124 (1954)] gives useful information on relationships of the genus.*

Over 60 species are recorded from New Zealand but the genus has never been the subject of critical study since Knight's paper [ T.N.Z.I. 12: 370-374 (1880)] where 19 new species are described. Zahlbruckner [ Denkschr. Akad. Wiss. Wien math.-naturwiss. K1. 104: 316-319 (1941)] described 8 new species mainly from South I., based on collections of J.S. Thomson (CHR, OTA, W) but did not revise the genus for New Zealand. The present account which discusses 19 taxa, is not a critical revision, but rather a preliminary evaluation of available type specimens with some ordering of obvious synonyms. Much detailed collecting remains to be done before the genus in this country is adequately known and it is likely that some taxa placed here in Bacidia will eventually be accommodated in other genera.

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* Dr J. Hafellner (Graz) suggests that foliicolous taxa in Bacidia be included in the family Byssolomataceae (pers. comm.)

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