New records in Thismia (Thismiaceae) for Pará state, northern Brazil

Abstract In the present study, we present new geographic distribution records of Thismia hyalina and T. melanomitra for Pará State, increasing the number of species of Thismiaceae in this state to three, with the previous register of T. singeri. The three species can be separated by the thickness of the roots, the presence of tuberous stems, outer tepal shape and colour, inner tepal shape and colour, and mitre presence. The description, taxonomic, ecological and geographic distribution comments along with photo plates of the studied species are presented.

Thismia Griff.belongs to the Thismiaceae family and occurs in the Old and New World, covering ca.90 species (Govaerts 2022).Despite the current circumscription of the genus encompassing New and Old World representatives, molecular studies suggest that Thismia is polyphyletic, with Neotropical representatives being a distinct group (Shepeleva et al. 2020).In Brazil, 18 species of Thismia have been identified; there is greater richness in the Atlantic Forest of the Southeast region, with 11 species (Flora e Funga do Brasil 2023).In Pará, northern Brazil, the first record of Thismia was reported less than a decade ago with Thismia singeri (de la Sota) Maas & H. Maas (Voloschen et al. 2013).This genus is represented by small mycoheterotrophic herbs, which are difficult to visualise in the field and are not very representative in Herbaria (Silva et al. 2020).However, the scientific dissemination of the group to the botanical community, together with the efforts in collecting expeditions, has gradually increased the number of new samples in scientific collections.These discoveries often correspond to new geographic distribution records or new species (Mancinelli et al. 2012;Voloschen et al. 2013;Guilherme et al. 2016;Silva et al. 2020Silva et al. , 2022Silva et al. , 2023;;Souza 2021;Engels et al. 2022;Silva & Braga 2022).
During a field expedition to the Tapajós River Basin in Pará, material from Thismia was Rodriguésia 74: e00712022.2023 found, collected and herborized according to standard techniques (Fidalgo & Bononi 1989).The specimens were destined for MBM and RB herbaria (acronyms according to Thiers, 2022 continually updated).The descriptions were made from the examined herborized material.Additionally, online databases were consulted to verify records of Thismia in the national territory and adjacent countries (CRIA 2022;Jabot 2022;Tropicos 2022).
In the present study, two new records of Thismiaceae for the state of Pará are presented: Thismia hyalina (Miers) Benth.& Hook.f.ex F.Muell., one of the species with the widest known distribution among congeners in the national territory, and T. melanomitra Maas & H. Maas, a species known only from the Ecuadorian type material and from a second Brazilian record from the state of Mato Grosso (Silva et al. 2020; Flora e Funga do Brasil 2022).
Based on available records of the species (Miers 1866; Maas et al. 1986 Thismia hyalina was found in sympatry and synchrony with T. melanomitra in Pará.This event must probably be related to the favourable ecological and environmental conditions in the area, favouring the development of mycoheterotrophic plants.This event has already been observed for Thismia species from Mato Grosso (Silva et al. 2020) and Thismia and other mycoheterotrophic species in southern Brazil (Souza 2021).
Thismia hyalina can be recognised among the other species that occur in Pará by the unthickened filiform roots, the presence of tuberous stem, outer tepals cylindrical and filiform, and by the inner tepals free, laminar, obovate.
Based on the study of different materials from different localities, it was noticed that T. hyalina presents considerable variation in the colour of the floral tube, ranging from pale orange (Miers 1866 [type]), whitish to yellowish with vertical red streaks (Maas et al. 1986), light salmoneus (Engels et al. 4777 and Engels 4779), white (Laessøe & Okino [SP 44991]), and light orange to red (Silva et al. 2020); in the present material from Pará, which is dark blue, the blue colour is more evident in newly opened flowers, becoming blacker when in full anthesis (Fig. 1).Maas & H. Maas, Opera Bot. 92: 141. 1987. Type: ECUADOR, PROVINCIA DE NAPO: Taguna Taracoa, Rio Napo, without data, Laessøe et al. 59947 (holotype AAU [spirit]; isotype U, [photos of live material in protologue seen]).This species is known thus far only from the Amazon Basin, Ecuador and Brazil (Mato Grosso and Pará [new record]) in the Amazon Forests (Maas & Maas 1987;Silva et al. 2020; Flora e Funga do Brasil 2023).In Pará, it was found in the understorey litter of the Terra Firme Forest in a well-drained environment and a shady place (Dense Ombrophilous Forest).

Thismia melanomitra
Based on the available records of the species (Maas & Maas 1987;Silva et al. 2020), T. melanomitra flowers from December to April and August and fruited from January to April.The material from Pará was in flower and had ripe fruits in February during the rainy season in the Brazilian Amazon.
Thismia melanomitra can be distinguished from the other species that occur in Pará by the elongated and thickened cylindrical roots; absence of tuberous stem; outer tepals laminar, ovate, white; inner tepals adnate, forming the mitre of black colour and by the mitre with superior hexagonal surface forming six foveolate triangles.
In contrast to the colour variation of T. hyalina, all known material of T. melanomitra, including the material from Pará, presents a fixed colour pattern, white flowers with tubes and mitre black (Fig. 2).
Although the new records presented here expand the known distribution of these rare mycoheterotrophic species, the deforestation and decrease in the original cover of the Brazilian Amazon Forest (e.g., Fearnside 2006Fearnside , 2017Fearnside , 2021)), which is advancing daily, represents a threat to the conservation of biodiversity, as well as these species and the general flora, since the region where they were found shows conspicuous strips of deforestation and forest degradation due to the irrational exploitation of timber resources (personal observation in loco).
; Maas-van de Kamer & Maas 2016; Silva et al. 2020), Thismia hyalina flowers from December to May and fruiting from December to March.The material from Pará was in flower and unripe fruits in February during the rainy season in the Brazilian Amazon.

Fig. 2 Figure 2
Figure 1 -a-h.Thismia hyalina -a.specimen in the leaf litter of the understorey, indicated by the arrow; b. general view of specimens; c. tube detail; d. flower detail in side view; e-f.flower detail in front view; g. specimen with immature fruit in the understorey litter; h.immature fruit detail.Photos by M.E.Engels from M.E.Engels & F.A.Silva 9607.