A TAXONOMIC REVISION OF HYMENOPHYLLACEAE

A. Ebihara et al.: A taxonomic revision of Hymenophyllaceae
TAXONOMIC TREATMENT
KEY TO THE GENERA
1a. Rhizomes long-creeping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
b. Rhizomes short-creeping or erect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2a. Rhizomes nearly glabrous or sparsely covered with light-coloured hairs. Involucres
usually bivalvate (Fig. 2a) . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Hymenophyllum
b. Rhizomes covered with reddish to dark-coloured hairs. Involucres usually not
bivalvate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3a. Roots absent or replaced by root-like shoots (Fig. 2c) . . . . . . . . . . . . . . . . . . . 4
b. Roots present . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4a. Continuous false veinlets parallel to true veins (Fig. 2d) present. Blade venation
catadromous (Fig. 2e) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Didymoglossum
b. Continuous false veinlets parallel to true veins absent. Blade venation anadro-
mous (Fig. 2f). . . . . . . . . . . . . . . . . . . 3. Crepidomanes (subg. Crepidomanes)
5a. Roots few and fine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Polyphlebium
b. Roots numerous and robust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6a. Blades once-pinnate to bipinnatifid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
b. Blades bipinnate to highly divided . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7a. Pinnae asymmetric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Vandenboschia
b. Pinnae symmetric . . . . . . . . . . . . . . . . . . . . . 7. Trichomanes (subg. Lacostea)
8a. Marginal laminar trichomes present . . . . 7. Trichomanes (subg. Trichomanes)
b. Marginal laminar trichomes absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9a. Abortive fronds (Fig. 2g) present. . . . . . . 3. Crepidomanes (subg. Nesopteris)
b. Abortive fronds absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10a. Minute clavate hairs present on stipes and rachises . . . . . . . 5. Vandenboschia
b. Minute clavate hairs on stipes and rachises absent . . . . . . . . . . 6. Abrodictyum
11a. Involucres bivalvate (Fig. 2a) . . . . . . . 1. Hymenophyllum (subg. Fuciformia)
b. Involucres tubular (Fig. 2b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
12a. Blade venation catadromous (Fig. 2e) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
b. Blade venation anadromous (Fig. 2f) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13a. Lamina tough, more than one cell thick . . . . . . . . 7. Trichomanes (subg. Feea)
b. Lamina membranous, one cell thick . . . . 7. Trichomanes (subg. Trichomanes)
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Fig. 2. Examples of morphological characters used in the keys. a. Bivalvate involucres (Hymenophyllum
deplanchei; Ebihara 001228-05, TI); b. tubular involucres with an exserted receptacle (Rc)
(Crepidomanes humile; Iwatsuki 99H06, TI); c. root-like shoots (RS) grown out from rhizomes (Rz)
(Crepidomanes bipunctatum; Ebihara 000225-020, TI); d. continuous false veinlets (FV) parallel
to true veins (TV) (Didymoglossum bipunctatum; S. Matsumoto 01-820, TNS); e. catadromous
venation – FAV: the first acroscopic vein; FBV: the first basiscopic vein in each pinna (Trichomanes
polypodioides; T.A. Ohsawa 178-15, TI); f. anadromous venation (Vandenboschia birmanica;
A. Narita 1070b, TNS); g. abortive fronds (pointed by an arrow) (Crepidomanes aphlebioides;
M. Kato et al. C-13883, TI); h. long bristle-like light reddish hairs on a stipe (Callistopteris apiifolia;
Ebihara 040922-03, TI); i. reduced lamina cells (Abrodictyum pluma; R. Jaman s.n., TI). — Scale
bars: a, b, d, h = 1 mm; c, e, f, i = 5 mm; g = 5 cm.
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