Adiantum (PPG I, 2016)

Kessler, Michael, Smith, Alan R. & Prado, Jefferson, 2017, Prodromus of a fern flora for Bolivia. XXVII. Pteridaceae, Phytotaxa 332 (3), pp. 201-250 : 230-232

Key to the Bolivian species of Adiantum

1 Blades 1-pinnate (rarely 2-pinnate at bases) .................................................................................................................................... 2

- Blades 2-pinnate or more divided ................................................................................................................................................... 13

2 Pinnae or pinnules articulate ............................................................................................................................................................ 3

- Pinnae or pinnules not articulate ...................................................................................................................................................... 5

3 Pinnae dimidiately lunate or semi-rounded reniform, long-stalked, stalks 1–2 cm long ........................................... A. philippense

- Pinnae deltate, flabellate to rhombic, stalked, stalks less than 1 cm long ........................................................................................ 4

4 Sterile margins ciliate, the cilia ca. 2 mm long; indusia rounded .............................................................................. A. delicatulum

- Sterile margins finely denticulate; indusia oblong to lunate ......................................................................................... A. deflectens

5 Rachises glabrous ............................................................................................................................................................................. 6

- Rachises with only scales or with scales and hairs ........................................................................................................................... 8

6 Pinnae ovate-deltate, opposite, subsessile or short-stalked; sori 2 per pinna; indusia linear ................................ A. macrophyllum

- Pinnae or pinnules ovate-lanceolate or suborbicular, alternate, long-stalked; sori more than 2 per pinna; indusia oblong or orbicular ............................................................................................................................................................................................ 7

7 Pinnae or pinnules suborbicular; sori borne on distal margins; indusia orbicular ........................................................ A. ruizianum

- Pinnae or pinnules ovate-lanceolate; sori borne on acroscopic and basiscopic margins; indusia oblong to shortly linear-arcuate .... ................................................................................................................................................................................... A. platyphyllum

8 Rachises with scales and hairs .......................................................................................................................................................... 9

- Rachises with only scales ............................................................................................................................................................... 10

9 Pinnae or pinnules glabrous on both surfaces; idioblasts easily visible on adaxial blade surfaces, mostly parallel between veins, not visible abaxially; indusia linear-arcuate ...................................................................................................................... A. petiolatum

- Pinnae or pinnules with filiform scales with pectinate bases on both surfaces; idioblasts conspicuous and oblique between veins adaxially and also visible abaxially; indusia oblong ..................................................................................................... A. obliquum

10 Blades with hairs on both surfaces, hairs 1–2 mm long .................................................................................................... A. scalare

- Blades with scales on both surfaces, scales with filiform apices and pectinate bases ................................................................... 11

11 Veins free; rhizomes long-creeping, non-nodose .................................................................................................. A. poeppigianum

- Veins anastomosing or irregularly anastomosing; rhizomes short-creeping and nodose ............................................................... 12

12 Pinnae or pinnules 6–9 times longer than wide, 4–5(–6) pairs, bases ± equal-sided, rounded to slightly cuneate; veins anastomosing ................................................................................................................................................................... A. dolosum

- Pinnae or pinnules 2–4 times longer than wide, 10–13 pairs, bases unequal-sided, rounded on acroscopic sides and cuneate on basiscopic sides; veins irregularly anastomosing but mostly free ................................................................................... A. lucidum

13 Blades 2-or 3-pinnate or 3–5-pinnate at bases ............................................................................................................................... 14

- Blades 2-pinnate ............................................................................................................................................................................. 29

14 Blades 3-to 5-pinnate at bases ........................................................................................................................................................ 15

- Blades 2-or 3-pinnate at bases ........................................................................................................................................................ 21

15 Blades forked and pedate at bases .................................................................................................................................................. 16

- Blades not forked at bases .............................................................................................................................................................. 17

16 Pinnules glabrous on both surfaces ....................................................................................................................... A. ornithopodum

- Pinnules with glandular hairs on both surfaces .................................................................................................................. A. patens

17 Pinnules tardily articulate, oblong to trapeziform; rachises glabrous .................................................................. A. mathewsianum

- Pinnules not articulate, dimidiate, orbicular, or flabellate, rhombic-cuneate; rachises pubescent or glabrous .............................. 18

18 Rachises with hairs and some scales; pinnules dimidiate, abaxially with hairs, glabrous adaxially .......................... A. pectinatum

- Rachises glabrous; pinnules orbicular to flabellate or rhombic-cuneate, abaxially with glands or glabrous and glabrous adaxially ......................................................................................................................................................................................................... 19

19 Blades abaxially with reddish rounded glands; pinnules rhombic-cuneate ....................................................................... A. moorei

- Blades glabrous abaxially; pinnules orbicular to flabellate ............................................................................................................ 20

20 Rhizomes long-creeping; pinnule bases usually symmetric; sori usually with yellow farina among sporangia; indusia membranaceous ................................................................................................................................................................. A. poiretii

- Rhizomes short-creeping; pinnule bases usually asymmetric; sori without farina among sporangia; indusia rigid ..... A. sinuosum

21 Pinnules articulate .......................................................................................................................................................................... 22

- Pinnules not articulate .................................................................................................................................................................... 25

22 Pinnules short-stalked, stalks ca. 1–3 mm long .............................................................................................................................. 23

- Pinnules long-stalked, stalks 0.5–1.5 cm long ............................................................................................................................... 24

23 Rhizomes short-creeping; pinnules dimidiate, ca. 3 times longer than wide; indusia oblong .................................. A. glaucescens

- Rhizomes long-creeping; pinnules not dimidiate, orbicular-cuneate; indusia round-reniform ............................... A. orbignyanum

24 Pinnules ovate-acuminate ................................................................................................................................................... A. anceps

- Pinnules ovate-trapeziform ........................................................................................................................................ A. peruvianum

25 Rachises puberulent; pinnules digitate-flabellate, puberulent on both surfaces ............................................................ A. digitatum

- Rachises glabrous; pinnules entire to incised, orbicular, orbicular-cuneate, rhombic-cuneate or ovate to rhombic, glabrous on both surfaces or pubescent abaxially ...................................................................................................................................................... 26

26 Pinnules pubescent abaxially ................................................................................................................................... A. camptorachis

- Pinnules glabrous on both surfaces ................................................................................................................................................ 27

27 Proximal pinnules overlying rachises; rhizome scales with sparsely denticulate margins .............................................. A. tinctum

- Proximal pinnules not overlying rachises; rhizome scales with entire margins ............................................................................. 28

28 Pinnules copiously incised on distal margins to 2/3 or more of pinnule length, pinnule bases cuneate and usually symmetric on proximal pinnules and asymmetric on distal pinnules .................................................................................................... A. lorentzii

- Pinnules entire or sometimes incised on distal margins to 1/2 of the pinnule length, pinnule bases broadly cuneate and usually asymmetric .................................................................................................................................................................. A. raddianum

29 Rachises glabrous on both sides or with only hairs adaxially ........................................................................................................ 30

- Rachises with only scales or with scales and hairs ......................................................................................................................... 31

30 Rachises glabrous on both sides; pinnules strongly reduced toward pinna apices ................................................. A. macrocladum

- Rachises puberulent adaxially and glabrous abaxially; pinnules gradually reduced toward pinna apices ............... A. tomentosum

31 Rachises with scales and hairs ........................................................................................................................................................ 32

- Rachises with only scales ............................................................................................................................................................... 33

32 Rhizomes long-creeping; pinnules glabrous on both surfaces; indusia glabrous .......................................................... A. latifolium

- Rhizomes short-creeping, nodose; pinnules abaxially with scales and glabrous adaxially; indusia bearing hairs ........ A. paraense

33 Rachises with one kind of scale (lanceolate to narrowly lanceolate with pectinate base) ............................................................. 34

- Rachises with two kinds of scales (hairlike and lanceolate with pectinate base or arachnoid and lanceolate with pectinate base) ... ......................................................................................................................................................................................................... 42

34 Pinnae 2–4 pairs per frond; pinnules abaxially with hairs ............................................................................................................. 35

- Pinnae 3–10 pairs per frond; pinnules abaxially with scales .......................................................................................................... 37

35 Pinnules 30–35 pairs per pinna; pinnules adaxially with hairs ............................................................................... A. villosissimum

- Pinnules 8–15 pairs per pinna, adaxially glabrous ......................................................................................................................... 36

36 Distal pinnules approximately half the size of largest pinnules; indusia glabrous ............................................................ A. humile

- Distal pinnules less than half the size of largest pinnules; indusia bearing hairs ....................................................... A. terminatum

37 Yellow, rounded glands present on abaxial surfaces of pinnules ................................................................................... A. dawsonii

- Glands lacking on abaxial surfaces of pinnules ............................................................................................................................. 38

38 Pinnules 2 times longer than wide .................................................................................................................................................. 39

- Pinnules 3–5 times longer than wide .............................................................................................................................................. 40

39 Margins of sterile blades serrate; indusia oblong with filiform (hairlike) scales having some processes (pectinate) at bases ........... ..................................................................................................................................................................................... A. multisorum

- Margins of sterile blades denticulate; indusia oblong with lanceolate scales having pectinate bases ................... A. squamulosum

40 Pinnules 30–45 pairs per pinna, sterile margins copiously denticulate-serrate; indusia scaly .................................... A. cajennense

- Pinnules 16–25 pairs per pinna, sterile margins irregularly serrate; indusia bearing hairs ............................................................ 41

41 Pinnules 3 times longer than wide, terminal pinnule larger than distal ones, broadly subrhombic ........................... A. diogoanum

- Pinnules 4–5 times longer than wide, terminal pinnule reduced, subrhombic, short-linear ................................. A. tuomistoanum

42 Rhizomes very long-creeping (cord-like) ....................................................................................................................................... 43

- Rhizomes moderately long-creeping or short-creeping ................................................................................................................. 46

43 Pinnules abaxially with septate hairs, adaxially glabrous; indusia glabrous ................................................................ A. windischii

- Pinnules abaxially with scales, adaxially glabrous; indusia with hairs or glabrous ....................................................................... 44

44 Scales of abaxial pinnule surfaces lanceolate with pectinate bases and filiform, uniseriate apices; indusia bearing hairs ................ ............................................................................................................................................................................. A. serratodentatum

- Scales of abaxial pinnule surfaces setiform; indusia glabrous ....................................................................................................... 45

45 Pinnules 3–8 pairs per pinna, terminal pinnules larger than distal ones, broadly subrhombic, sterile margins biserrate ................... .......................................................................................................................................................................................... A. argutum

- Pinnules 4–15 pairs per pinna, terminal pinnules reduced, narrowly subrhombic, sterile margins finely serrate ......... A. incertum

46 Rhizomes short-creeping, slender; pinnules abaxially with scales and hairs, scales hairlike, hairs 1–1.5 mm long; indusia with scales .............................................................................................................................................................................. A. solomonii

- Rhizomes moderately long-creeping, stout; pinnules abaxially with scales, scales with pectinate bases and filiform apices; indusia glabrous or with hairs ..................................................................................................................................................................... 47

47 Rachises adaxially mostly with filiform scales (hairlike) and abaxially with lanceolate scales with pectinate bases; indusia oblong, more than one per pinnule, with hairs, hairs reddish brown .................................................................................... A. tetraphyllum

- Rachises on both sides mostly with arachnoid scales and some lanceolate scales with pectinate bases; indusia linear, lunate, usually one per pinnule, glabrous or with brown hairs ...................................................................................................... A. pulverulentum