A new species and a new variety of Radula Dumort. (Radulaceae, Marchantiophyta) from Brazil

Abstract

In the course of a taxonomic study of Radula in Brazil, a new species from Bahia and a new variety of R. fendleri from Rio de Janeiro were detected. The new species is characterized by plants irregularly pinnate, leaves oblong-ovate with entire to sinuate margins, cell walls with small trigones at leaf base and midleaf, increasing in size toward the leaf margins, and lobules distant to subimbricate with a rounded base, covering 2/3 to fully overlapping the stem. The new variety differs from the type variety by plants paroicous, leaf cells with trigones small or lacking, and absence of caducous leaves. A full description and illustration of the new taxa as well as comments on morphology, taxonomy, and distribution are provided.

Full text

Phytotaxa 454 (1): 024–030
https://www.mapress.com/j/pt/
Copyright © 2020 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
24 Accepted by Matt von Konrat: 14 Jul. 2020; published: 27 Jul. 2020
https://doi.org/10.11646/phytotaxa.454.1.2
A new species and a new variety of Radula Dumort. (Radulaceae,
Marchantiophyta) from Brazil
FUVIO RUBENS OLIVEIRA-DA-SILVA1,4, S. ROBBERT GRADSTEIN2,5 & ANNA LUIZA ILKIU-BORGES3,6
1 Posgraduation Program in Biological Sciences–Tropical Botany (UFRA/MPEG), Museu Paraense Emílio Goeldi, Coordination of
Botany, Av. Perimetral 1901, 66530-070 Belém, Brazil.
2 Muséum National d’Histoire Naturelle, Institut de Systématique, Évolution, Biodiversité (UMR 7205), C.P. 39, 12 Rue Buffon, 75005
Paris, France.
3 Museu Paraense Emílio Goeldi, Coordenação de Botânica, Av. Magalhães Barata 376, 66040-170, Belém, Pará, Brazil.
4
�
oliveira.fuvio@gmail.com; https://orcid.org/0000-0002-4871-6740
5
�
gradstein@mnhn.fr; https://orcid.org/0000-0002-3849-6457
6
�
ilkiu-borges@museu-goeldi.br; https://orcid.org/0000-0002-1266-7211
Abstract
In the course of a taxonomic study of Radula in Brazil, a new species from Bahia and a new variety of R. fendleri from Rio
de Janeiro were detected. The new species is characterized by plants irregularly pinnate, leaves oblong-ovate with entire
to sinuate margins, cell walls with small trigones at leaf base and midleaf, increasing in size toward the leaf margins, and
lobules distant to subimbricate with a rounded base, covering 2/3 to fully overlapping the stem. The new variety differs
from the type variety by plants paroicous, leaf cells with trigones small or lacking, and absence of caducous leaves. A full
description and illustration of the new taxa as well as comments on morphology, taxonomy, and distribution are provided.
Keywords: Radula bahiensis, Radula fendleri var. paroica, Liverworts, Taxonomy
Introduction
Radula Dumortier (1822: 112) is a genus that includes about 200 species worldwide, occurring from the Arctic to
Antarctic regions with greatest diversity in the tropics and subtropics (Yamada 1979, 2003, Gradstein et al. 2001,
Söderström et al. 2016). The members of the genus usually occur on bark, decaying wood, or living leaves, rarely
on rock or soil, inhabiting diverse environments, from sea level to over 4000 m elevation (Gradstein et al. 2001,
Devos et al. 2011a). Morphologically, the genus presents singular characteristics such as (1) Radula-type branches
(originating from a stem epidermal cell and therefore associated with an unmodified leaf), (2) incubous, lobulate
leaves, (3) underleaves absent, (4) rhizoids in tufts on lobule surface, and (5) perianth tubular, dorsiventrally flattened
(Schuster 1980b, Gradstein et al. 2001, Yamada 1979, Crandall-Stotler et al. 2009).
Several studies have dealt with the Radula species of Brazil. The first species lists were published by Yano (1984,
1989, 1995), totalling 39 species. Afterward, Yamada (2003) recognized 29 species in the country and Yano (2008) 34.
Most recently, Costa & Peralta (2015) reported 26 species from Brazil.
In a taxonomic study of Radula in Brazil by the first author (unpublished data) 30 species are accepted so far,
including the recently described Radula yamadae F.R.Oliveira-da-Silva & Ilkiu-Borges (in Oliveira-da-Silva & Ilkiu-
Borges (2020: 288). In the course of this study, a new species from Bahia and a new variety of Radula fendleri Gottsche
(1984:146) from Rio de Janeiro were detected.
The aim of this paper is to describe these new taxa, with illustrations and comments on their morphology, taxonomic
affinities, and distribution.

A NEW SPECIES OF RADULA DUMORT. Phytotaxa 454 (1) © 2020 Magnolia Press • 25
Taxonomic treatment
Radula bahiensis F.R.Oliveira-da-Silva, Ilk.-Borg. & Gradst., sp. nov. (Fig. 1)
Dioicous. Plants irregularly pinnate. Leaves widely spreading, imbricate, oblong-ovate, margins entire to sinuate; cell walls thin, trigones
small at leaf base and midleaf, increasing in size toward the leaf margins, cuticle smooth. Lobules distant to subimbricate, oblong,
inflated along the keel, base rounded, covering 2/3 to fully overlapping the stem, apex rounded to obtuse, distal margin ± straight to
rounded; keel straight to sinuate-concave, spreading at angles of 30‒40º with the stem.
Type:—BRAZIL. Bahia: Uruçuca, 6.2 Km N of town of Serra Grande, ca. 40 Km N of Ilhéus along coast, wet tropical forest with small
stream in ravine, 14°26’ S, 39°03’ W, 200 m, 17 July 1991, Vital & Buck 20271 (holotype SP-353920!, isotype MG!).
Dioicous. Plants 2‒3.5 mm wide, green to olive-green in herbarium, irregularly pinnate branched. Stems in cross section
with ca. 29 thick-walled epidermal cells surrounding ca. 47 thin-walled medullary cells, epidermal and medullary cells
of the same size, epidermal cell walls brown, medullary cell walls yellowish, trigones small. Leaves widely spreading,
imbricate, slightly convex, oblong-ovate, 1‒1.8 mm long, 0.6‒1.1 mm wide, dorsal base rounded, overlapping the
stem, apex rounded to obtuse, margin plane, entire to sinuate; marginal cells subquadrate, 12‒20(‒30) × 10‒15 µm,
median and basal cells isodiametric to elongate, 20‒25(‒30) × 15‒20 µm, cell walls thin, trigones small at leaf base
and midleaf, increasing in size toward the margins, cuticle smooth. Lobules distant to subimbricate, oblong, 0.7‒0.9
mm long, 0.5‒0.7 mm wide, ca. 1/2 of the lobe length, inflated along the keel, insertion line ± straight, base plane,
rounded, covering 2/3 to fully overlapping the stem, free margin plane, straight, apex rounded to obtuse, distal margin
± straight to rounded; keel straight to sinuate-concave, spreading at angles of 40‒50º with the stem. Rhizoids colorless,
scanty. Androecia intercalary to terminal on long branches, 2‒4 pairs of bracts, 1.1‒1.4 mm wide; bracts ovate, 0.8‒1
mm long, 0.3‒0.5 mm wide, apex rounded, margin plane, entire to sinuate, lobule distant to contiguous, ovate, ca. 3/4
of lobe length, base rounded, free margin straight, apex rounded; keel convex, inflated. Gynoecia terminal on long
branches, with one subfloral innovation; bracts oblong-ovate, 1‒1.3 mm long, 0.6‒0.8 mm wide, apex rounded, margin
plane, entire, lobule ovate, ca. 1/3 of lobe length, apex rounded. Perianth not seen. Vegetative reproduction by stem
fragmentation and caducous Lejeunea-type branches.
Distribution and habitat:—This species is only known from the state of Bahia (Brazil), growing on tree trunks
in Atlantic forest, at 50‒200 m elevation. The examined specimens were collected in three municipalities of Bahia,
located close to each other and near the ocean (Fig. 2).
Etymology:—The epithet of the new species refers to its known distribution.
Taxonomic notes:—Radula bahiensis is characterized by (1) plants irregularly pinnate; (2) leaf lobes widely
spreading, imbricate, oblong-ovate, apex rounded to obtuse, margin entire to shallowly sinuate; (3) leaf cells with
small trigones at leaf base and midleaf, increasing in size toward the leaf margins; (4) lobules distant to subimbricate,
oblong, inflated along the keel, base rounded, covering 2/3 to fully overlapping the stem, apex rounded to obtuse, distal
margin straight to rounded, keel straight to sinuate-concave, spreading at angles of 30‒40º with the stem.
The specimens were identified as R. kegelii Stephani (1884: 152) (=R. pallens (Sw. 1788: 143) Montagne (1839:
71), fide Gradstein (in press) in herbaria NY and SP. At first glance, the new species indeed resembles R. pallens by
plants relatively robust (2 to 3 mm wide), leaf lobes widely spreading, and lobule keel straight to sinuate-concave.
During the taxonomic study of Radula in Brazil, 108 specimens of R. pallens were compared with the isolectotype
of R. kegelii (G-00264270!) and confirmed for 15 states of Brazil, including Bahia. However, R. bahiensis and R.
pallens are clearly different. Plants of R. bahiensis are never dichotomous, while varying from irregularly pinnate
to dichotomous in R. pallens. Additionally, R. bahiensis presents leaves oblong-ovate with rounded to obtuse apex
(suborbicular with broadly rounded apex in R. pallens); trigones small at base and midleaf increasing in size toward
the margins (trigones usually lacking in R. pallens); lobules distant to subimbricate and large, 0.7‒0.9 × 0.5‒0.7 mm
(distant and small, 0.3‒0.6 × 0.2‒0.5 mm, in R. pallens); base covering 2/3 to fully overlapping the stem (usually
covering 1/4‒1/2 of stem in R. pallens).
By the size of the leaf cells and presence of trigones, R. bahiensis seems rather similar to the Andean R. jamesonii
Taylor (1846: 375). However, R. bahiensis differs from the latter species mainly by leaves never falcate and lobule
base covering 3/3 to fully overlapping the stem. In R. jamesonii, leaf lobes are usually falcate and lobule bases cover
maximally 1/2 the stem width.

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26 • Phytotaxa 454 (1) © 2020 Magnolia Press
FIGURE 1. Radula bahiensis ˗ A. Habit with gynoecia. B. Marginal leaf cells. C. Median leaf cells. D. Habit with androecia. E, J. Habit.
F. Cross section of a stem. G–I. Lobules. K. Leaves. (A, C, G, H, I, K= 500 µm; B, D= 25 µm; F= 50 µm; E, J= 1000 µm; A, E from SP-
353920; D from NY-1670325; B, C, F, G, H, I, J, K from SP-373105).

A NEW SPECIES OF RADULA DUMORT. Phytotaxa 454 (1) © 2020 Magnolia Press • 27
The specimen from herbarium SP (SP-373105) presented intercalary branches at the base of lobules (Lejeunea-
type), beside the typical Radula-type branches (Figure 1J). Crandall (1969) named these “adventitious Radula-type”
branches, reporting them from R. longituba Stephani (in Herzog 1916: 87) (=R. mammosa Spruce [1890: 127])
(Crandall 1969, plate 19–21) and Radula sp. (plate 19), and mentioned that they were associated with decapitated
shoots. The latter observation was also made in R. bahiensis.
Additional specimens (paratypes):—BRAZIL. Bahia: Una, Maruim, border of the fazendas Maruim and Dois de
Julho, 33 km SW of Olivença on road from Olivença to Burarema, Southern Bahian wet forest, epiphytic on tree, in
full shade, 28 April 1981, Boom et al. 811 (NY-1670325!); Ilhéus, “área do CEPEC (Centro de Pesquisas do Cacau),
km 22 da rodovia Ilhéus/Itabuna BR415, restinga, cipó grosso, restinga arenosa e muito sol,” 14°47’20” S, 39°02’58”
W, 50 m, 17 July 1991, Vital s.n. (SP-373105!).
FIGURE 2. Distribution of Radula bahiensis (black dot) and R. fendleri var. paroica (white dot).

OLIVEIRA-DA-SILVA ET AL.
28 • Phytotaxa 454 (1) © 2020 Magnolia Press
FIGURE 3. Radula fendleri var. paroica. A. Marginal leaf cells. B, C, F, J. Habit. D. Cladograph of fertile plants (open ellipse= gynoecia
with perianth; solid ellipse= androecia). E. Leaf, dorsal view. G. Median leaf cells. H. Cross section of a stem. I. Leaf lobes. (A, G= 25
µm; B, C, E, F, J= 500 µm; H= 50 µm; I= 250 µm; A–J from RB-99454).

A NEW SPECIES OF RADULA DUMORT. Phytotaxa 454 (1) © 2020 Magnolia Press • 29
Radula fendleri var. paroica F.R.Oliveira-da-Silva, Ilk.-Borg. & Gradst., var. nov. (Fig. 3)
Differs from Radula fendleri var. fendleri by plants paroicous, trigones lacking or small, caducous leaves absent.
Type:—BRAZIL. Rio de Janeiro: Nova Friburgo, “Estrada para Teresópolis, sobre pau podre na capoeira,” 6 May 1927, Vaughan
Bandeira s.n. (holotype RB-99454!).
Monoicous (paroicous). Plants 1‒1.8 mm wide, brown in herbarium, irregularly pinnate. Stems in cross section with ca.
16 thick-walled epidermal cells surrounding ca. 13 thick-walled medullary cells, epidermal and medullary cells of the
same size, cell walls brownish, trigones large. Leaves widely spreading, imbricate, strongly convex, ovate to falcate-
ovate, 0.6‒0.8 mm long, 0.5‒0.6 mm wide, dorsal base rounded, overlapping the stem, apex rounded to obtuse, margin
strongly recurved, entire; marginal cells subquadrate, 7‒10 µm diam., median and basal cells isodiametric to elongate,
15‒25 × 10‒15 µm, cell walls thin, trigones lacking to small, cuticle verruculose. Lobules distant, subrectangular,
0.3‒0.5 mm long, 0.1‒0.3 mm wide, ca. 1/2 the lobe-length, strongly inflated along the keel, insertion line slightly
arched, base plane, rounded, covering 1/3(‒1/2) the stem, free margin plane, ± straight, apex plane, rounded, rarely
obtuse, distal margin ± straight; keel arched, spreading at angles of 45‒60º with the stem. Rhizoids colorless, scanty.
Androecia terminal or preceding a gynoecia on short branches, 1‒3 pairs of bracts, 0.55‒1 mm wide; bracts ovate,
0.45‒0.75 mm long, 0.2‒0.4 mm wide, apex rounded, margin strongly recurved, entire, lobule ovate, ca. 3/4 of lobe
length, base rounded to obtuse, free margin ± straight, apex rounded to obtuse. Gynoecia terminal on long branches,
with 1‒2 subfloral innovations; bracts ovate, 0.75‒1 mm long, 0.55‒0.6 mm wide, apex rounded, margin recurved,
entire, lobule oblong, ca. 1/2 of lobe length, apex obtuse. Perianth subcylindrical, 1.8‒2.2 mm long, 0.65‒0.9 mm
wide at apex, mouth entire to irregularly undulate. Vegetative reproduction not observed.
Distribution and habitat:—Radula fendleri var. paroica is known from Rio de Janeiro only, growing on decaying
wood in humid Atlantic Forest.
Etymology:—The epithet of the new variety refers to its paroicous condition.
Taxonomic notes:—The new variety differs from the typical variety by plants paroicous (dioicous in var. fendleri),
leaf cells with trigones small or lacking (trigones large in var. fendleri), and by the absence of caducous leaves (caducous
leaves present in var. fendleri).
Due to its monoicous condition, the new variety may be confused with another monoicous species that occur in
Brazil, R. mexicana Lindenberg & Gottsche (1863: 150). However, this species differs from R. fendleri var. paroica by
the subquadrate lobule with usually elongate apex. In addition, R. mexicana is usually autoicous.
Acknowledgment
The authors are grateful to Dr. Rafaella C. Forzza and Dr. Barbara Thiers for logistic support during the visit to the
Herbaria RB and NY, respectively; to Dr. Denilson F. Peralta for the loan of Radula specimens from Herbarium SP;
to the Museu Paraense Emílio Goeldi and the Programa de Pós-graduação em Ciências Biológicas-Botânica Tropical
(UFRA/MPEG) for logistical support; to the National Council for Scientific and Technological Development (CNPq)
for the Master’s fellowship grant of the first author (process n°132059/2018-5), and for the productivity fellowship grant
of the third author (process n°302374/2016-7). This study was financed in part by the Coordenação de Aperfeiçoamento
de Pessoal de Nível Superior-Brasil (CAPES)-Finance Code 001.
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