Advances in knowledge of Manihot (Euphorbiaceae) from Brazil

: Herbarium-based studies and extensive fi eld work revealed the existence of a new species in the genus Manihot which is restricted to the municipality of Itirapina, in the state of São Paulo, Brazil. Characteristics such as the size and morphology of the leaves and bracts were important to recognize M. irregularis as a new taxon. Description, illustration, as well as comments on its morphology, distribution, conservation status, and a key for the identifi cation of Manihot species for the state of São Paulo are presented


INTRODUCTION
The concern for cassava's wild parents is justifi ed once this species is an important food resource in developing countries (FAO 2019) and their most near species show promising results for cassava breading purposes (Boaventura et al. 2015).In addition, many of these are endangered species, especially due to a small extent presence and the degradation of their habitats (Walter & Gillet 1998, Martins et al. 2017a).
Ever since 2010 our team performs expeditions to various Brazilian ecosystems, collecting and identifying accessions of wild relatives of cassava (Manihot esculenta Crantz) (Ledo et al. 2010).Since then, diverse new populations were located and therefore expanding the collections of wild parents preserved by the Brazilian Agricultural Research Corporation (EMBRAPA) and by the Federal University of Recôncavo da Bahia (UFRB) and new herbarium vouchers, increasing also the data concerning the Extent of Occurrence (EOO) and Area of Occupation (AOO) from various species of the genus Manihot.These data allowed the description of new species (e.g.M. bellidifolia P. Carvalho & M. Martins, M. breviloba P. Carvalho & M. Martins, M. macrocarpa P. Carvalho & M. Martins) and the review of their conservation status (Martins et al. 2011, 2014, Martins & Ledo 2015, Martins et al. 2017a,b).
The highest diversity of Manihot in Brazil in concentrate in the Cerrado region (60 spp.), a biome that extends through the central portion of South America (Simon et al. 2018, Murphy et al. 2016).New species are frequently summarized (Mendoza et al. 2015, Silva 2016) and the number of species computed in Brazil has already exceeded 100 (Martins et al. 2020) in contrast with about 80 species registered in the last revision of the genus for the country (Rogers & Appan 1973).In the São Paulo state ten species are known, being the Cerrado the richest biome (7 spp.) (Orlandini & Lima 2014).
Commentaries: Manihot irregularis M. Martins & Ledo forms vast populations in Cerrado areas in the municipality of Itirapina, State of São Paulo, Brazil, typically in open shrubby vegetation.In most of the analyzed collections, the materials are identified as M. tripartita (Spreng.)Arg.(or M. aff.tripartita) due to the shrub habit associated with the number of leaf lobes (1-3) and orbicular to ovoid capsules.These species can be easily differentiated by the oval bracts of M. tripartita which differ from the linear bracts of M. irregularis.The morphological variation of leaves in M. irregularis also approximates this species to M. anomala characterized by showing leaves with a variable number of lobes and with diverse formats, e.g.elliptical, oval or oboval (Pohl 1827, Rogers & Appan 1973, Flora do Brasil 2020).It can be differentiated from M. anomala Pohl, by the smaller subshrub (< 50 cm tall), linear bracts (ca.0.5 mm wide) and caruncle with 1/2 seed length (3-5 mm), while M. anomala shows shrub to lianescent habit (1.5-4 m), ovate semifoliaceous to foliaceous bracts (>2 mm wide) and caruncle with 1/5 seed length (up to 2 mm length).The ratio of the caruncle to the seed length is the largest ever observed in Manihot species.
Etimology: The name of this species is related to the morphology of leaves, extremely variable, with lateral lobes reduced or asymmetric and entire or variable sinuous margin (Fig. 2).Conservation: Population analyses were not performed for M. irregularis, preventing the evaluation of criteria A, C and D from the International Union for Conservation of Nature (IUCN 2014).Nevertheless, from distribution data evaluated by the Geospatial Conservation Assessment Tool (GeoCAT) (http://geocat.kew.org/), according to Bachman et al. (2011), the species was considered "Critically Endangered" (CR) due to the extent of occurrence (EOO) with 0.946 km 2 (Fig. 3) and the area of occupation (AOO) with 8 km 2 .

Figure 1 .
Figure 1.Manihot irregularis M. Martins & Ledo.(a) with leaves variably lobed.(b) and (c) Leaves.(d) Staminate bud with bracts and bracteoles.(e) Staminate flower.(f) Seeds in frontal and lateral view.Observe the proportion of caruncle in relation of the size of seed.