Cheilolejeunea (Spruce) Stephani (1890: 284)

Gil-Novoa, Jorge Enrique & Costa, Denise Pinheiro, 2023, Synopsis of the species of Cheilolejeunea (Marchantiophyta, Lejeuneaceae) in the Pacific dominion and Páramo province of tropical America, Phytotaxa 587 (2), pp. 73-120 : 77-79

Cheilolejeunea (Spruce) Stephani (1890: 284) . —

Lejeunea subg. Cheilolejeunea Spruce (1884: 251) :

Type:— Lejeunea decidua Spruce (1884: 257) . BRAZIL. Amazonas: Manaos, ad fl. Negro ostia, in cortice (MANCH!, lectotype designated by Grolle 1983).—

Cheilolejeunea decidua ( Evans 1905: 188) .

Plants small or large, 250–2500 µm wide, light green, yellowish green, orange, light brown, dark brown, or greyish, growing attached to the substrate or hanging on tree trunks and shrub branches; branches Lejeunea - type. Stems in cross section with or without hyalodermis, 80–300 µm in diameter, 7–20 epidermal cells, 8–35 medullary cells; ventral merophyte 2–10 cells wide. Leaves subimbricate to imbricate, convolute, orbicular, ovate, oblong or triangular, margin entire, rarely dentate or ciliate, apex rounded, acute to acuminate; cells orbicular, hexagonal or ovate, plane to mammillose or rarely papillose, on the dorsal side, with often conspicuous trigones, intermediate thickenings absent, few (1–4) and usually large granular oil bodies (filling ca. 60–80% of the cell lumen), and ocelli usually absent (very rare). Lobules never reduced, ovate, rectangular or globose, free margin generally involute, with one or two tooth; first tooth not developed or very small (1–2 cells long), second tooth formed by one to five cells, hyaline papilla on the internal margin of the base of the first tooth; keel arched, smooth or sometimes mammillose or papillose. Underleaves bifid or undivided, 1–6 × stem width, imbricate to distant, margins entire, base cuneate, rounded or auriculate, with almost straight to very deep, U-shaped insertion. Monoicous or dioicous. Androecia commonly on the branches, with 2–6 pairs of strongly inflated bracts. Gynoecia terminal on the main axis or branches, with or without lejeuneoid or pycnolejeuneoid innovations. Perianth terete or 2–5(-10) keels, with or without teeth. Vegetative reproduction by caducous branches or leaves.

Notes:—Although almost none of the characteristics that define Cheilolejeunea are constant ( Bastos 2017), the genus is characterized by the leaf margins generally entire, lobules normally inflated and never reduced, lobules with frequent reduction of the first tooth, and hyaline papilla positioned distally to the second tooth; cells often with conspicuous trigones, few (1–4) and usually large granular oil bodies (60–80% of the cell lumen), ocelli usually absent ( Gradstein et al. 2013, Wilson et al. 2007, Bastos 2017, Gradstein 2021, Gradstein & Reiner-Drehwald 2017).

The species generally grow as epiphytes on tree trunks and on the branches of trees and shrubs, less frequently on rocks and rotting logs; rarely observed growing on living leaves or soil (Supplementary material, Table 1). Although no epiphyllous records were found in the studied material, Gradstein (2021) mentioned that Cheilolejeunea acutangula ( Nees 1833: 357) Grolle (1979: 173) can be found on living leaves, while Zartman & Ilkiu-Borges (2007) comment that C. holostipa ( Spruce 1884: 171) Grolle & Zhu (2001: 1071) , C. lobulata (Lindenberg in Gottsche et al. 1845: 353) Gradstein & Bastos (2020: 29), C. trifaria ( Reinwardt et al. 1824: 226) Mizutani (1964: 132) , and C. rigidula ( Montagne 1840: 336) Schuster (1971: 102) occur rarely on leaves in the forests of central Amazon. This explains the fact that no material occurring on leaf was found or studied.

Thirty-one species and four varieties are recognized in the study area, representing 56% of the Neotropical diversity and approximately 19% of the global diversity of that genus (Gradstein 2021). All species and varieties occur in the Pacific dominion (Guatuso-Talamanca, Puntarenas-Chiriquí, Chocó-Darién, Guajira, Trinidad, Magdalena, Sabana, Cauca, Galápagos Islands, Western Ecuador, and Ecuadorian provinces) with the exception of Cheilolejeunea erostrata Schuster (1978: 427) , which appears to be endemic to the SATZ in the Páramo province, and C. schiavoneana Reiner & Gradstein (2017: 326) the only species endemic to the Pacific dominion, occurring in Cauca province (Supplementary material, Table 1). However, of the total number of taxa found (35 taxa), only nine are shared between the two biogeographic regions (Pacific dominion and Páramo province). These results showed that the diversity of species of Cheilolejeunea cannot delimit the biogeographical dominions, with there being no differences between the species composing the two biogeographical regions (Pacific dominion and SATZ), and that the number of endemic species is low (one species in each region). These results are in agreement with those found by Gradstein (2021) for the Galápagos province, where endemism is high for many plants and animals ( Tye et al. 2002, Dal Forno et al. 2017), but not for the genus Cheilolejeunea , which does not have any endemic species in this province. In addition to this, several records that, according to the geographical coordinates, belong to the province of Páramo, actually belong to other provinces, such as Cauca or Magdalena, taking into account aspects such as altitude and type of vegetation (see explanatory notes on the distribution and habitat of the species).

Within the Pacific dominion, the Magdalena province has the greatest number of taxa (26), followed by Cauca (23), Puntarenas-Chiriquí (20), and Guatuso-Talamanca (16). Regarding the distribution of species by vegetation type in this dominion, 27 taxa are recorded for the lower montane rainforest (700–2400 m), 20 for the upper montane rainforest (2500–3400 m), and 16 for the lowland rainforest (0–700 m). In general terms, the distribution of Cheilolejeunea species in the Pacific dominion presents a pattern similar to the altitudinal distribution of bryophytes in Colombia ( Bernal 2016) and in Ecuador ( León-Yanez et al. 2006), where the greatest diversity is found in the montane rainforest of the Andean region (Cauca, Magdalena, and Paramo provinces), decreasing considerably towards the coastal zones and arid regions of the Pacific dominion, such as the provinces of Guajira (12 taxa), western Ecuador (3), and Ecuadorian (2). However, our results partially differ in terms of the distribution of vascular plants of Colombia and Ecuador, where the Andean region presents the greatest diversity in forests below 2000 m ( Bernal 2016, Jørgensen & León-Yánez 1999).

Regarding the conservation status of the species studied, most of the Cheilolejeunea species reported in both biogeographic regions (Pacific dominion and the Páramo province) were considered non-threatened based on the number of records, the number of localities, and the qualities of the habitats in which they occur. On the one hand, three species of Cheilolejeunea are included in the vulnerable category (VU – D2) in the red book of bryophytes of Colombia (Linares & Uribe 2002): C. aurifera ( Schuster 1978: 429) Ye et al. (2015: 325) , C. tonduzana ( Stephani 1911: 721) Ye et al. (2015: 326) , and C. paramicola ( Herzog 1934: 95) Ye et al. (2015: 326) , as they are known from less than three locations. However, with the realization of this study, and that of Gradstein (2021), these species are currently considered to be of Least Concern (LC), as they are currently known for several countries in South and Central America for more than 10 different localities and are not suffering any type of threat (fire, tourism, agriculture, etc.).

In this study, only Cheilolejeunea erostrata , an endemic species of the Venezuelan Andes described 45 years ago ( Schuster 1978) and known only from its type locality ( Gradstein & Bastos, 2020), is considered here as Critically Endangered (CR-B1a), taking into account its extent of occurrence and number of locations ( Hallingbäck et al. 1998, UCN 2001).

Cheilolejeunea cuspidifera Bastos et al. (2016: 39) , C. ornata Bastos (2011: 86) , and C. schiavoneana , three recently described species (after 2011), are considered here as Data Deficient-new (DD-n), a new category created by Sérgio et al. (2007) that includes only recently described or reported taxa.

Key to the species of Cheilolejeunea occurring in the Pacific dominion and the Páramo province (SATZ dominion)

1. Lobules globose and strongly swollen, free margin inrolled..........................................................................................18. C. lineata

- Lobules not globose, free margin involute, but not inrolled ..............................................................................................................2

2. Lobule apex with two distinct teeth, usually overlapping each other ......................................................................... 3. C. aneogyna

- Lobule with one tooth.........................................................................................................................................................................3

3. Lobule tooth long, acute, hyaline .......................................................................................................................................................4

- Lobule tooth short, obtuse, not hyaline (or apparently absent) ..........................................................................................................7

4. Underleaves undivided ..............................................................................................................................................13. C. holostipa

- Underleaves bifid................................................................................................................................................................................5

5. Ventral merophyte on main stems 4–6 cells wide. Caducous leaf lobes produced on upright flagelliform shoots with densely imbricate underleaves......................................................................................................................................... 27. C. schiavoneana

- Ventral merophyte on main stems 2 cells wide. Caducous leaf lobes produced on ordinary leafy shoots with distant underleaves, upright flagelliform shoots lacking ....................................................................................................................................................6

6. Leaves often with rhizoids at margin. Vegetative reproduction by caducous leaves. Dioicous................ 2.1. C. adnata var. adnata

- Leaves without rhizoids at margin. Caducous leaves absent. Autoicous ............................................................................................. .............................................................................................................................................................................................................. 2.2. C. adnata var. autoica

7. Stems in cross section with hyalodermis............................................................................................................................................8

- Stems in cross section without hyalodermis.......................................................................................................................................9

8. Leaf apex rounded ............................................................................................................................................................................19

- Leaf apex sharp to apiculate.............................................................................................................................................................26

9. Plants pale glaucous or light green. Underleaves undivided............................................................................................................10

- Plants light green to brown. Underleaves undivided or short-bifid..................................................................................................11

10. Leaves plane to slightly convex and ventral margin of leaf lobes plane. Lobule tooth 3–5 cells long.......................30. C. unciloba

- Leaves strongly convex and ventral margin of leaf lobes involute. Lobule tooth 0–3 cells long ........................ 31. C. xanthocarpa

11. Plants dioicous, yellowish green to pale brown, never dark brown. Lobules maximally 1/3 × lobe length, subquadrate-trapezoid .. ..........................................................................................................................................................................................................12

- Plants autoicous, yellowish green to dark brown. Lobules 2/5–1/2 × lobe length, rectangular.......................................................16

12. Leaf apex rounded. Underleaves orbicular or wider than long. Perianth usually terete, rarely keeled or angled............................13

- Leaf apex obtuse to acuminate. Underleaves clearly longer than wide. Perianth keeled.................................................................15

13. Perianth terete...................................................................................................................................11.1. C. filiformis var. filiformis

- Perianth keeled .................................................................................................................................................................................14

14. Perianth bluntly 4-keeled.............................................................................................................. 11.2. C. filiformis var. platycoleus

- Perianth sharply 5-keeled .................................................................................................................... 11.3. C. filiformis var. wallisii

15. Leaf apex acuminate. Underleaves short-bifid.................................................................................................................16. C. jackii

- Leaf apex obtuse. Underleaves undivided....................................................................................................................... 22. C. ovalis

16. Dorsal surface of leaf cells mammillose-papillose; the cells distinctly elevated and the outer wall thickened by a tuberculate papilla ............................................................................................................................................................................ 5. C. aurifera

- Dorsal surface of leaf cells smooth or mammillose, not papillose...................................................................................................17

17. Plants orange brown to dark brown, ascending to pendent. Perianth with 5–6 strong keels and 4–5 additional weaker keels........... ................................................................................................................................................................................ 23. C. paramicola

- Plants pale-colored to dark brown, creeping to ascending, not pendent. Perianth with 5 keels, without keels or with 3–4 rounded keels in the upper half.......................................................................................................................................................................18

18. Ventral merophyte 4–6 cells wide. Perianth without keels or 3–4 rounded keels in the upper half. Plants of montane forest and subpáramo.................................................................................................................................................................28. C. tonduzana

- Ventral merophyte 2–3 cells wide. Perianth sharply 5-keeled. Plants of páramo ..........................................24. C. quinquecarinata

19. Ventral merophyte 4–8 cells wide ....................................................................................................................................................20

- Ventral merophyte 2 cells wide ........................................................................................................................................................21

20. Underleaves imbricate with apical margin strongly revolute...................................................................................... 25. C. revoluta

- Underleaves distal, imbricate to contiguous, apical margin flat...................................................................................... C. valenciae

21. Underleaves bifid to 1/4 or 1/5 of length, reniform...........................................................................................12. C. fragrantissima

- Underleaves more deeply bifid, orbicular to broadly ovate. ............................................................................................................22

22. Underleaves 4–6× stem width ..........................................................................................................................................................23

- Underleaves 1.5–3.5× stem width ....................................................................................................................................................24

23. Underleaves wider than long. Autoicous.................................................................................................29.2. C. trifaria var. trifaria

- Underleaves orbicular. Dioicous ..............................................................................................................29.1. C. trifaria var. clausa

24. Plants less than 0.6 mm wide. Underleaves less than 2 × stem width..........................................................................9. C. discoidea

- Plants 0.6–2 mm wide. Underleaves 2–4 × stem width ...................................................................................................................25

25. Plants autoicous or paroicous, always fertile, innovations pycnolejeuneoid. .......................................................... 15. C. intertexta

- Plants autoicous or dioicous, innovations lejeuneoid...................................................................................................26. C. rigidula

26. Leaf margin toothed, lobed to ciliate-crenate...............................................................................................................20. C. norisiae

- Leaf margin entire to crenulate.........................................................................................................................................................27

27. Leaf cells strongly mammillose-papillose........................................................................................................................................28

- Leaf cells smooth or mammillose, but not papillose........................................................................................................................30

28. Ventral merophyte 4–6 cells wide. Leaves imbricate................................................................................................. 4. C. asperrima

- Ventral merophyte 2 cells wide. Leaves distant to subimbricate......................................................................................................29

29. Plants 0.7–1.5 mm wide. Underleaves 3–4.5 × stem width, insertion line deeply arched ............................................ 14. C. inflexa

- Plants less than 0.6 mm wide. Underleaves 1.5–2 × stem width, insertion line straight................................................ 21. C. ornata

30. Lobules small, 1/5 of the leaf length or less. Underleaves reniform.............................................................................6. C. beyrichii

- Lobules more 1/5 of the leaf length. Underleaves ovate, obovate or orbicular, not reniform..........................................................31

31. Plants 1–2 mm wide .........................................................................................................................................................................32

- Plants less than 1 mm wide ..............................................................................................................................................................33

32. Lobules about 1/2 of leaf length................................................................................................................................. 10. C. erostrata

- Lobules 1/3–2/5 of leaf length...................................................................................................................................17. C. laevicalyx

33. Underleaves distant, 1.5–2.5 × stem width.................................................................................................................. 19. C. lobulata

- Underleaves distant or contiguous, 2.5–4 × stem width...................................................................................................................34

34. Leaf cells smooth, underleaf bases cuneate. Innovations lejeuneoid ............................................................................. 8. C. comans

- Leaf cells mammillose-papillose, underleaf bases auriculate. Innovations pycnolejeuneoid.................................. 1. C. acutangula