Expanding the distribution of Tapanhuacanga campinorum (K.Krause) P.L.R.Moraes (Rubiaceae, Rubioideae) to central-western Brazil: the first record for the State of Mato Grosso, in the Parque Estadual do Cristalino

Expandindo a distribuição de Tapanhuacanga campinorum (K.Krause) P.L.R.Moraes (Rubiaceae, Rubioideae) para o Centro-Oeste do Brasil: o primeiro registro para o Estado de Mato Grosso, no Parque Estadual do Cristalino

ABSTRACT

We report the occurrence of Tapanhuacanga campinorum in the Parque Estadual do Cristalino, in the State of Mato Grosso, Central-West Brazil. This represents the first record of the genus in this State and the species in this region of the country, since T. campinorum was known only from the Amazonian campinas vegetation in the States of Amazonas and Pará, in the northern region of Brazil. We further comment on the distribution, conservation, and taxonomic aspects of this species.

Keywords:
Amazon forest; Amazonian campinas; Brazilian flora; Cerrado; Spermacoceae

RESUMO

Relatamos a ocorrência de Tapanhuacanga campinorum no Parque Estadual do Cristalino, no Estado do Mato Grosso, Centro-Oeste do Brasil. Este representa o primeiro registro do gênero neste estado e da espécie nesta região do país, já que T. campinorum era conhecida apenas das vegetações de campinas amazônicas dos Estados do Amazonas e Pará, na região Norte do Brazil. Comentamos ainda sobre a distribuição, conservação e aspectos taxonômicos desta espécie.

Palavras-chave:
Amazônia; campina amazônica; Cerrado; flora brasileira; Spermacoceae

Introduction

Psyllocarpus Mart. & Zucc. is an endemic genus from Brazil. As currently circumscribed, the genus is distributed in the Amazonia, Caatinga, and Cerrado phytogeographic domains and comprises 13 species (Kirkbride 1979, Carmo et al. 2018a, Sobrado et al. 2022). It is nested in the Spermacoce clade in the mostly herbaceous Spermacoceae, a tribe characterized by, but not always, the fimbriate stipules and tetramerous flowers (Kårehed et al. 2008, Salas et al. 2015, Carmo et al. 2022, Nuñez Florentin et al. 2022). Among its relatives, Psyllocarpus is distinct mainly by the septifragal capsules compressed parallel to a persistent septum (von Martius 1824, Kirkbride 1979).

Moraes (2019) has proposed new combinations of Psyllocarpus under the obscure Tapanhuacanga, its priority name. Such a proposal was based solely on nomenclatural reasons and did not involve a detailed and critical examination of herbaria material. Thus, to promote stability and the use of a long-established name, consistently used ever since its publication (von Martius & Zuccarini 1824), Carmo et al. (2019) proposed to conserve the name Psyllocarpus. Also, the monophyly of Tapanhuacanga remains to be tested, as well as how it relates to the other genera in the Spermacoce clade, hence some of the combinations by Moraes (2019) might be relegated to synonymy. Nevertheless, the proposal by Carmo et al. (2019) was not recommended (Applequist 2023, Wilson 2023), therefore the name Tapanhuacanga should be used from now on (Turland et al. 2018).

In the latest classification of the genus, when it was still called Psyllocarpus, Kirkbride (1979) divided it into two sections, namely Psyllocarpus sect. Psyllocarpus and P. sect. Amazonica J.H.Kirkbr., based on geographical distribution and morphology. Psyllocarpus sect. Psyllocarpus, which follows the concept of von Martius (1824), is characterized by the terete leaves, homostylous flowers, prolate-spheroidal pollen grains, psilate tectum with spinules generally distributed along each side of the colpi exine, and a weakly bilobate to rarely capitate stigma. This section is found in the Cerrado and campo rupestre of the Espinhaço range and the Planalto Central of eastern and central Brazil, in the States of Bahia, Goiás, Minas Gerais, and the Distrito Federal. Currently, this section comprises nine species (Kirkbride 1979, Carmo et al. 2018a, Sobrado et al. 2022).

On the other hand, the species included in the genus as Psyllocarpus sect. Amazonica present planar leaves, heterostylous flowers, oblate-spheroidal pollen grains, perforated tectum, finely and evenly spinulose exine, and deeply bifid stigma. The three species in this section are restricted to white-sand Amazonian campinas from the northern region of Brazil, occurring in the States of Amazonas, Pará, and Rondônia (Kirkbride 1979).

Two species have been described but not classified in any section. Tapanhuacanga intermedia (E.L.Cabral & Bacigalupo) P.L.R.Moraes (Cabral & Bacigalupo 1997), an endemic species from Bahia, northeastern Brazil, was not assigned to any section because of divergent characteristics that do not fully correspond to either P. sect. Psyllocarpus or P. sect. Amazonica (Cabral & Bacigalupo 1997, Carmo et al. 2023), while T. densifolia (Zappi & Calió) P.L.R.Moraes (Zappi et al. 2014), which also corresponds to the first synonym created by Moraes (2019), was transferred to a monotypic genus of its own, namely Diadorimia J.A.M.Carmo, Florentín & R.M.Salas (Carmo et al. 2022).

As our ongoing revision of Tapanhuacanga progresses, our field expeditions and examination of herbaria material have led to several taxonomic novelties (Carmo et al. 2017, 2018a, 2018b, 2022, 2023, Sobrado et al. 2022). During a visit to the SPF herbarium, we came across a duplicate collection of Sazaki 2126, which belongs to Tapanhuacanga campinorum (K.Krause) P.L.R.Moraes. This species was then included in Psyllocarpus sect. Amazonica and is known to occur in the States of Amazonas and Pará, northern Brazil (Kirkbride 1979). However, this particular collection was made in the Parque Estadual do Cristalino, in the State of Mato Grosso, in the central-western region of the country. Thus, this represents the first record of the genus in this State and the species in this region. Therefore, we here report this new record of T. campinorum, and further comment on its distribution, conservation, and taxonomy.

Material and methods

We analyzed the protologue of the basionym Borreria campinorum K.Krause and specimens from the CTES, F, IAN, MG, MO, NY, RB, SPF, and US herbaria in person, and HGB and K online (acronyms according to Thiers continuously updated). The distribution map was elaborated using the QGIS® software (QGIS Development Teams 2018). An informal assessment of conservation status was carried out by range size (B criterion), following the IUCN Standards and Petitions Committee (2022) recommendations. Extent of occurrence (EOO) and area of occupancy (AOO) were estimated using GeoCAT (Bachman et al. 2011).

Results and Discussion

Tapanhuacanga campinorum (K.Krause) P.L.R.Moraes in Feddes Repert. 130: 51. 2019 ≡ Psyllocarpus campinorum (K.Krause) J.H.Kirkbr. Smithsonian Contr. Bot. 41: 13. 1979 ≡ Borreria campinorum K.Krause in Verh. Bot. Vereins Prov. Brandenburg 50: 118. 1908 (publ. 1909). Description in Kirkbride (1979). Type: BRAZIL - Amazonas, “Campina an den Cachoeiras des Marmelos”, III-1902, Ule 6102 (lectotype [designated by Kirkbride (1979)] HBG 521835 [digital image]!; isotypes F!, K [digital image]!).

Material examined: BRAZIL. Amazonas: Estrada Transamazônica, 1-VI-1979, T.R.Bahia 25 (IAN); Manicoré, BR 230, Rodovia Transamazônica, a 243 km de Humaitá, 7°40’S, 61°10’W, 24-IV-1985, C.A.C.Ferreira 5815 (INPA, MG, MO, RB); Transamazon Highway, 53 km W of the Aripuanã river, 27-VI-1979, C.E.Calderón 2695 (MO, NY, US); 9 km W of Rio dos Pombos, ca. 1.5 km E of Igarapé dos Pombos, and ca. 64 km E of the Aripuanã, 18-VI-1979, C.E.Calderón 2560 ( F , NY). Mato Grosso: Novo Mundo, Parque Estadual do Cristalino, Serra do Rochedo, limite sul do Parque, acesso pela Fazendo AJJ, alt. 459 m, 9°41’16’’S, 55°26’30’’W, 02-II-2008, D.Sasaki 2126 (K, SPF). Pará: Region of Missão Velha, a Mundukurú village ca. 2 km N of the Rio Cururú, alt. ca. 200 m, 7°45’S, 57°20’W, 13-II-1974, W.R.Anderson 10918 (IAN, MO, NY, US).

Geographical distribution: Tapanhuacanga campinorum is found in the northern region of Brazil, specifically in the campinas, which is a form of low, woody vegetation found on podzolized white-sand soils. Campinas usually present low species diversity, and their flora contains a number of endemics (Lisbôa 1975). Tapanhuacanga campinorum is found along the Rio Marmelos and Rio Aripuanã near the Transamazonian Highway, in the State of Amazonas, as well as in sandy areas along the Rio Cururú, in Pará (Kirkbride 1979). This species also thrives in the central-western region of the country, specifically in Parque Estadual do Cristalino, in the municipality of Novo Mundo, Mato Grosso, where it can be found in areas with opened vegetation associated with rocky outcrops (figure 1).

Figure 1.
Distribution map in Brazil of Tapanhuacanga campinorum (K.Krause) P.L.R.Moraes (Rubiaceae, Rubioideae). AM: State of Amazonas. MT: State of Mato Grosso. PA: State of Pará.

Preliminary conservation status: Tapanhuacanga campinorum presents EOO and AOO equal to 45002 km² and 12 km², respectively (kml file available as supplementary file https://figshare.com/s/1d6de4a30eda8ddb48fd). Until this point, this species was known to occur in the northern region of Brazil. We therefore expand its distribution by recording its occurrence in the central-western region of the country, in the Parque Estadual do Cristalino, a conservation unit of integral protection, in the municipality of Novo Mundo, Mato Grosso. Nevertheless, the criteria for the threatened categories are to be applied to a taxon whatever the level of conservation action affecting it (IUCN Standards and Petitions Committee 2022).

The EOO of T . campinorum would qualify the species as Least Concern (LC). However, due to the very nature of the campinas, which is a patchy type of vegetation where this species grows, we believe the AOO would be a more accurate estimate of this species distribution. Therefore, T. campinorum is preliminary assessed as Endangered EN B2ab(iii), based on the AOO (less than 500 km²), occurrence in three locations, and an inferred continuing decline of the quality of the habitat, due to the advance of extensive cattle ranching and soybean plantations, among others, in the region (Fearnside 2005).

The rate of native vegetation loss along the southern and eastern edges of the Amazon domain in this region, which is called the “arc of deforestation”, is dramatic. Although Amazonian forest is cut for various reasons, cattle ranching predominates (Fearnside 2005). In fact, in an analysis of the spatial variability of the reasons for the deforestation in the Amazon in Brazil from 2010 to 2019, it was observed that the average variable of number of oxen was the one that showed the highest correlation with deforestation. Thus it was found that the livestock sector in southern Amazonia is the main economic agent that pressures large areas of deforestation, since stockfarming is practiced extensively (Santos et al. 2021).

Comments: In the last taxonomic revision of the genus, when it was still called Psyllocarpus, Kirkbride (1979) classified it into two sections based on morphology and geographic distribution, expanding the circumscription of the genus (von Martius & Zuccarini 1824, von Martius 1824). Such a circumscription was mainly due to the weight that was given to a single character, the capsules compressed parallel to the septum. The new classification resulted in a rather heterogeneous genus, with Psyllocarpus sect. Amazonica sharing the compressed capsules with P. sect. Psyllocarpus but distinctively differing in other features, such as planar leaves (as opposed to terete in P. sect. Psyllocarpus), heterostylous flowers (instead of homostylous with included stamens and style), and perforate tectum (rather than psilate).

In addition to the morphological and geographic differences, the species included in Tapanhuacanga (Moraes 2019) as the so called Psyllocarpus sect. Amazonica were either transferred from other genera or newly described. Tapanhuacanga campinorum was transferred from Borreria G.Mey. and T. psyllocarpoides (Sucre) P.L.R.Moraes from Staelia Cham., while T. cururuensis (J.H.Kirkbr.) P.L.R.Moraes was described by Kirkbride (1979). Therefore, the monophyly of Tapanhuacanga remains to be tested, as well as how it relates to the other genera in the Spermacoce clade.

Regardless of the identity of T. campinorum, which is being investigate by our group, it is its first record in the central-western region of Brazil and in the State of Mato Grosso, in the Parque Estadual do Cristalino (image of a duplicate of Sasaki 2126 deposited at K available at https://specieslink.net/rec/745/K000652747, incorrectly identified as Borreria spicata (Miq.) Bacigalupo & E.L.Cabral). This is the largest conservation unit located in the “Cristalino region”, a term usually used to refer to the Mato Grosso portion of the Cristalino River basin, a tributary of the Teles Pires River, which rises in Serra do Cachimbo, in southern Pará (Zappi et al. 2011).

Since its establishment, the Parque Estadual do Cristalino has been embroiled in a series of disputes about its boundaries, with tensions escalating after 2006. The most significant of these disputes involved opposing factions of social actors. On one hand were those who advocated for preserving the park’s existing boundaries, including organized civil society groups and researchers. On the other hand, there were those who advocated for a reduction in the park’s size, such as farmers and large landowners (Pereira & Nascimento 2010). As of today the Parque Estadual do Cristalino, despite its relatively small size in Amazonian terms (184,900 ha), is considered one of the most relevant conservation units, as it is located on an edge of the Brazilian Amazon, in a transition zone with the Cerrado, and harbours exceptional biodiversity (Pereira & Nascimento 2010).

Zappi et al. (2011) conducted a floristic survey of vascular plants in the Parque Estadual do Cristalino, which identified 1,366 species belonging to 626 genera and 151 families. The survey documented at least seven previously unknown species and several endemics from the Serra do Cachimbo, along with new records for Mato Grosso and Brazil. The authors anticipated that future investigations would increase the number of species even further, as is the case of our study. Given its exceptional biological diversity, particularly in an ecotone region of the Amazonian periphery that is relatively understudied, and the ongoing threat of deforestation pushing northwards into the basin, conservation efforts in the Cristalino should be a top priority (Zappi et al. 2011).

Acknowledgments

João Afonso Martins do Carmo acknowledges Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), for the doctoral fellowship; CAPES for the PDSE scholarship (Process 88881.135488/2016-01); the Missouri Botanical Garden, for the Shirley A. Graham Fellowship in Systematic Botany and Biogeography; the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET -Argentina) for the postdoctoral fellowship; the staffs of the CTES, F, IAN, MG, MO, NY, RB, SPF, and US herbaria; Luisa de Pontes Ribeiro, for elaborating the distribution map of Tapanhuacanga campinorum; and Andreza Stephanie de Souza Pereira, for the photographs of Psyllocarpus collections deposited at the MG herbarium.

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Edited by

Associate Editor: Alain Chautems

Publication Dates

• Publication in this collection
  12 Aug 2024
• Date of issue
  2024

History

• Received
  11 Dec 2023
• Accepted
  04 Apr 2024