A new species of Parianella (Poaceae, Bambusoideae, Olyreae) marks the southernmost distribution of the genus in Brazil

Background and aims – Parianella is a relatively recently described genus of the subtribe Parianinae (Poaceae, Bambusoideae, Olyreae) that includes two species, and it is supposedly endemic to the Bahian Coastal Forests in the central region of Atlantic Forest, Brazil. Herein, we describe and illustrate a new species of the genus, comparing it with the other species of Parianella . We also provide an updated distribution map of the genus and the conservation status of the new taxon. Material and methods – This study was based on the analysis of herbarium specimens and a literature review. The conservation assessment is based on field observations and spatial analyses, following IUCN guidelines and criteria. Key results – During a review of the Poaceae collection of the MBML Herbarium, two Parianinae specimens with interesting features were found. A detailed morphological analysis revealed that these specimens belong to a new species of Parianella . The new taxon was collected in two localities in the southern portion of the Brazilian state of Espírito Santo, one in the municipality of Santa Leopoldina and the other in the Duas Bocas Biological Reserve, municipality of Cariacica. Both localities are situated in the Krenák-Waitaká Forests, one of the three subregions of the central Atlantic Forest region, and an area of great floristic diversity, including bamboo species. Conclusion – Parianella capixaba represents the southernmost distribution of the genus known to date. With the description of this new species, the total number of bamboos in Espírito Santo state rises to 52 species in 18 genera.


INTRODUCTION
Parianella Hollowell, F.M.Ferreira & R.P.Oliveira (Poaceae, Bambusoideae, Olyreae) is one of three monophyletic lineages of the subtribe Parianinae, and it includes two species (Ferreira et al. 2019). Like other Parianinae, Parianella has fimbriae at the apex of the leaf sheaths and spiciform synflorescences (Ferreira et al. 2019). Synflorescences of Parianella and Pariana Aubl. are composed only of gynecandrous whorls with four or five staminate spikelets surrounding a single central pistillate spikelet (Ferreira et al. 2013a). However, the former has staminate spikelets with elongated, laminar pedicels much longer than the associated spikelet, while Pariana has staminate spikelets with pedicels shorter than or equal to the associated spikelet (Ferreira et al. 2013a(Ferreira et al. , 2019. This characteristic of the staminate spikelet is interpreted as a morphological synapomorphy of Parianella (Ferreira et al. 2019). Microechinate-perforate ectexine ornamentation of the pollen grains is also interpreted as synapomorphic in Parianella (Ferreira et al. 2019), in contrast to the microechinate-areolate ectexine pattern observed in the Pariana+Eremitis clade (Dórea et al. 2017;Ferreira et al. 2019).
While Pariana (ca 28 species) is distributed throughout the Amazon Basin, extending into wet forests of Central America (Hollowell 1987;Judziewicz et al. 1999;Ferreira et al. 2019;Dias et al. 2021), Eremitis Döll (17 species) and Parianella have their distributions restricted to the Brazilian Atlantic Forest (Ferreira et al. 2013a(Ferreira et al. , 2013b(Ferreira et al. , 2016(Ferreira et al. , 2019(Ferreira et al. , 2020a(Ferreira et al. , 2020b(Ferreira et al. , 2020c(Ferreira et al. , 2020d(Ferreira et al. , 2021a(Ferreira et al. , 2021b(Ferreira et al. , 2022. Despite being considered a hotspot for world biodiversity conservation (Mittermeier et al. 2004), the Atlantic Forest is one of the most endangered rain forests on Earth (Ribeiro et al. 2009;Joly et al. 2014). Formerly covering about 1.0 to 1.5 million km 2 in Brazil, from Rio Grande do Sul state (South region) to Rio Grande do Norte (Northeast region), the Atlantic Forest currently lies shattered into disconnected small forest fragments (Ranta et al. 1998;Ribeiro et al. 2009;Rezende et al. 2018). It is estimated that only 28% of its original vegetation cover is left in Brazil (Rezende et al. 2018). Even so, three centres of endemism can be recognized in the Atlantic Forest: northern (Pernambuco and Alagoas states), central (southern Bahia, north-eastern Minas Gerais, and Espírito Santo state), and southern (from Rio de Janeiro to Santa Catarina states) regions (Thomas et al. 1998;Murray-Smith et al. 2009). The central region, in turn, can be divided into three subregions, based on the shifts in availability of both humidity and solar radiation (energy) (Saiter et al. 2016). According to the latter authors, these subregions are: Bahia Interior Forests (moist and dry forests of north-eastern Minas Gerais and inland Bahia), Bahia Coastal Forests (BCF) (wet forests north of 18-19°S), and Krenák-Waitaká Forests (KWF) (moist forests south of 18-19°S, in Espírito Santo state). The entire territory of the state of Espírito Santo lies in the central region of the Atlantic Forest, split into the BCF and KWF subregions (Saiter et al. 2016;Alves-Araújo et al. 2022). The central region of the Atlantic Forest harbours high biodiversity and incidence of endemic and threatened species (Thomas et al. 1998;Martini et al. 2007;Ostroski et al. 2018), including bamboos (Soderstrom et al. 1988;Clark 1990;Oliveira et al. 2011;Ferreira et al. 2020a).
During a review of the Poaceae collection of the MBML Herbarium of the Instituto Nacional da Mata Atlântica (INMA), municipality of Santa Teresa, Espírito Santo state, two Parianinae specimens with interesting morphological features were found. After a careful analysis, it was confirmed that they belong to a new species of Parianella. The new species was collected in the municipalities of Santa Leopoldina and Cariacica, both in Espírito Santo. These localities are situated in the KWF subregion (Saiter et al. 2016). This is the first record of Parianella outside Bahia state and represents the southernmost distribution of the genus known so far. The total number of bamboos in Espírito Santo thereby rises to 52 species (nine endemics) and 18 genera. This finding reinforces the fact that Espírito Santo, along with Bahia and Minas Gerais, is an important centre of diversity for bamboos in Brazil (Soderstrom et al. 1988;Clark 1990;Oliveira et al. 2011;Ferreira et al. 2020aFerreira et al. , 2020bFerreira et al. , 2020cFerreira et al. , 2020dFerreira et al. , 2021aFerreira et al. , 2021bFerreira et al. , 2022.

MATERIAL AND METHODS
The morphological description and geographical distribution of the new species were based on the specimens housed in the herbaria CEPEC, HUEFS, MBML, RB, and UPCB (acronyms according to Thiers 2022). Morphological characters of the other two congeneric species were taken from their type specimens [Parianella , isotype), and original descriptions (Oliveira et al. 2004;Trinius 1834Trinius [1835). We used Tutin (1936), Hollowell (1987), and Judziewicz et al. (1999) for morphological bamboo terminology. We followed Harris and Harris (2001), and Gonçalves and Lorenzi (2011) for the classification of leaves, reproductive structure forms, and indumentum. Measurements of the vegetative and reproductive structures were taken using a metal calliper with 0.02 mm precision, following Hollowell (1987) and Ferreira et al. (2013a).

Staminate spikelets
Length (mm) 4-5 2-2.5 2.5-3.2 Pedicel length (mm) 9-13 7-8. characterized as a semi-deciduous seasonal submontane forest, due to climatic conditions, altitudinal ranges, and soil types (Assis et al. 2007). Parianella capixaba represents the southernmost distribution of the genus known so far since the other two species (P. carvalhoi and P. lanceolata) are endemic to Bahia state. Etymology. The specific epithet "capixaba" is a noun in apposition and the local name for Espírito Santo inhabitants. The epithet also alludes to the first record of the genus Parianella outside Bahia state. IUCN conservation assessment. Endangered: EN B2ab(ii,iii,iv (Table 1). However, the new species can be differentiated by its longer and wider leaf blades (40-47 × 4-5 cm vs (6-)11.5-20 × 2.1-3.4 cm in P. carvalhoi and (7.5-)11-16(-21.4) × 0.7-1.7(-2.5) cm in P. lanceolata), longer synflorescences (ca 15 cm long vs 6.5-8 cm in P. carvalhoi and 5-8 cm in P. lanceolata), and longer staminate spikelets (4-5 mm long vs 2-2.5 mm in P. carvalhoi and 2.5-3.2 mm in P. lanceolata) with longer pedicels (9-13 mm long vs 7-8.2 mm in P. carvalhoi and 7.2-8 mm in P. lanceolata) and longer glumes (3.5-4 mm long vs 2-3 mm in P. carvalhoi and 2.2-3 mm in P. lanceolata) ( Table 1). A remarkable characteristic of the new species is its well-developed rhizomes, in contrast with both P. carvalhoi and P. lanceolata, which have poorly developed rhizomes (Judziewicz et al. 1999;Oliveira et al. 2004). The absence of well-developed rhizomes in the latter two species (treated as Pariana at that time) was considered by Soderstrom and Calderón (1974) as "primitive" (plesiomorphic) in comparison to Pariana from Amazon and Central America. However, according to Ferreira et al. (2019), the loss of a rhizome system in Parianella could be regarded as derived, which could be investigated with the well-developed rhizome observed in P. capixaba. More studies, including molecular phylogenetic analyses, are necessary to test this hypothesis.