Synopsis of the genus Pycnolejeunea (Spruce) Schiffn. (Lejeuneaceae, Marchantiophyta) in Brazil

Hoehnea 47: e1132019. http://dx.doi.org/10.1590/2236-8906-113/2019 ABSTRACT – (Synopsis of the genus Pycnolejeunea (Spruce) Schiffn. (Lejeuneaceae, Marchantiophyta) in Brazil). Pycnolejeunea is a pantropical genus represented in Brazil by nine species, according to the present treatment. Pycnolejeunea chocoensis M.E. Reiner & Gradst., recently described for Colombia, is being cited for the first time for Brazil. Descriptions are given for all species and illustrations only for Pycnolejeunea chocoensis , Pycnolejeunea contigua (Nees) Grolle, Pycnolejeunea papillosa X.-L. He and Pycnolejeunea porrectilobula C.J. Bastos & O. Yano. A key to the species of Pycnolejeunea occurring in apresentadas todas e para Pycnolejeunea contigua (Nees)


Introduction
Pycnolejeunea (Spruce) Schiffn. (Lejeuneaceae) is a pantropical genus of 14 accepted species (Söderström et al. 2016, Bastos & Zartman 2017. The genus was monographed by He (1999) who recognized nine species: five restricted to the Neotropics, three in Asia and Australia, and P. contigua (Nees) Grolle, with a wide, pantropical distribution. However, recently two new species were described: P. remotistipula  (Ye et al. 2015). To date, Brazil is known to host nine species (in the present treatment), four of which are presently considered to be restricted to the Amazon Region: P. gradsteinii (State of Pará), P. chocoensis, P. remotistipula, and P. decurviloba (State of Amazonas) (Bastos & Zartman 2017).
In the context of the current studies on the Lejeuneaceae of Brazil, we have recently discovered several novelties for Pycnolejeunea. Here we present a taxonomic treatment of Pycnolejeunea species known from Brazil, including detailed morphological descriptions and illustrations. Herein we also report Pycnolejeunea chocoensis as a new record for Brazil.

Material and methods
This study is largely based on examination of type material and herbarium specimens from ALCB, F, G, INPA, MG, SP, and RB. Fresh material has also been examined from recent collections.
The preliminary species list of Pycnolejeunea in Brazilian Flora 2020 (Bastos 2019) served as a baseline for the study. For each species the following information is provided: descriptions, presently recognized synonyms, references to published illustrations, general comments, global and regional (Brazilian) distributions (based on collections studied and on literature), vegetation types, substrate types and other selected material. Distribution for Brazil is based on geopolitical regions following the IBGE (Northern, Northeastern, Middle-Western, Southeastern, Southern). Accepted names follows Söderström et al. (2015Söderström et al. ( , 2016. Selected species of Pycnolejeunea were observed and digitally photographed following sputter coating with gold, using scanning electron microscope (SEM) JEOL JSM-661OLV, in the Laboratório Multiusuário de Microscopia Eletrônica (LAMUME), of the Instituto de Física da Universidade Federal da Bahia (Institute of Physics, Federal University of Bahia).

Results and Discussion
In the present study nine species of Pycnolejeunea are recognized for Brazil, representing nearly ca. 64,3% of the total species described in worldwide. The sub-generic and sectional classification presented by He (1999) is not followed in the present treatment, however, the species concept of Pycnolejeunea and their nomenclatural synonyms as defined by He (1999) are followed herein.
To date, P. chocoensis, P. gradsteinii, P. decurviloba, and P. remotistipula occur only in the Amazon region of Brazil. However, P. decurviloba has a broader distribution, also occurring in Central America, and P. chocoensis is disjunct from the Chocó region of Colombia, thus being the first reference of the species in Brazil.
Pycnolejeunea species commonly occur in ombrophylous forest, seasonal forest, cerrado and restinga, usually growing on live tree trunk, liana, decomposing logs, and rarely on leaves (P. contigua and P. macroloba, according to Zartman & Ilkiu-Borges 2007). Some of the distinctive characters of Pycnolejeunea, such as large trigones, pycnolejeuneoid innovations and mamillose to papillose leaf lobe cells, are also found in Cheilolejeunea. They differ, however, in their lobular structure relative to the first and the second teeth and, consequently, in the relative position of the hyaline papilla. In the majority of members of Lejeuneaceae, specifically in the tribe Lejeuneeae, the free margin of the lobule bears one or two teeth, which are separated or rarely lightly associated (He 1996, Bastos 2010, Renner 2012. In some taxa, however, one or both lobule teeth can be reduced. Mizutani (1961) found that the hyaline papilla is always proximal to the first tooth, either marginal or ental (on the inner side of the lobule) and distal to the second tooth. In other words, the position of the hyaline papilla depends on whether the first or the second lobule tooth is prominent. In Pycnolejeunea the first tooth is prominent and the second tooth is reduced.
According to He (1999), the ocelli of Pycnolejeunea are generally variable in number and may occur isolated or aggregated basally (confined to the leaf lobe base) to suprabasally near leaf lobe base to the proximal half of the leaf lobes, and female bracts.
Although the presence of ocelli is an important and diagnostic feature of Pycnolejeunea, in some species (P. decurviloba, P. remotistipula, and P. chocoensis) they are always absent and others, such as P. contigua, occasionally absent.

Pycnolejeunea
Pycnolejeunea chocoensis can be recognized by the decurved leaf lobule (the lobule apex is positioned towards the ventral margin of the leaf lobe), absence of ocelli (in some specimens examined from Amazon, A.M. Sierra 5104, C.E. Zartman 10232, 1-2 ocelli were observed) and ventral merophytes with two cells wide. P. chocoensis is similar to P. decurviloba (both species has decurved leaf lobules and lack of ocelli), but the latter species is a larger plant with reniform underleaves and ventral merophyte with 4-6 cells wide. The absence of ocelli is also shared with P. remotistipula, but the latter species has rectangular leaf lobule and underleaves with rounded lobes apex.
World distribution: Widespread in tropical America (He 1999 Description and illustration: He (1999).
Pycnolejeunea papillosa is characterized by leaf lobe and lobule cells with huge, rounded papillae (see figure 4), free margin of leaf lobule composed by 5-6 cells, and imbricate, orbicular to reniform underleaves. According to He (1999), P. papillosa can be confused with P. contigua, but P. papillosa is a very different plant due to leaf cells with a huge, rounded papillae, strongly convex leaves and leaf lobe margins crenulate.
In the original description of Pycnolejeunea porrectilobula the presence of only one ocellus is mentioned, but in the other materials examined, 2-4 ocelli were found. The presence of pluripapillose leaf cells was also not mentioned in the original description of P. porrectilobula. To date, P. porrectilobula has only been reported for the State of Bahia.