A Tropicoporus species among the types of Fulvifomes swieteniae

Abstract

Fulvifomes swieteniae, is considered a synonym of F. cedrelae based on morphological, molecular, and ecological data. The type materials of F. swieteniae were revised in this work and based on our morphological observations and a reappraisal of the literature, the holotype fits the taxonomic concept of F. cedrelae, while the paratype corresponds to Tropicoporus linteus. Given these facts, the paratype of F. swieteniae is determined as T. linteus by perennial basidioma with a hyphal system that is monomitic in the context and dimitic in the trama of the tubes, hymenial setae, and colored basidiospores that become darker in KOH solution.

Key words:
accurate identification; Hymenochaetaceae; morphological features; taxonomy; type revisions

Resumo

Fulvifomes swieteniae é considerada sinônimo de F. cedrelae com base em dados morfológicos, moleculares e ecológicos. Os materiais tipo de F. swieteniae foram revisados neste trabalho e com base em nossas observações morfológicas e reinterpretação da literatura, o holótipo da espécie se enquadra no conceito taxonômico de F. cedrelae, enquanto o parátipo se trata de Tropicoporus linteus. Diante desses fatos, o parátipo de F. swieteniae é determinado como T. linteus por seu basidioma perene com sistema hifal monomitico no contexto e dimitico na trama dos tubos, setas himeniais e basidiósporos coloridos que escurecem em solução de KOH.

Palavras-chave:
identificação precisa; Hymenochaetaceae; características morfológicas; taxonomia; revisão de tipos

Fulvifomes swieteniae Murrill is characterized by basidiomata with a slightly cracked pileal surface, a context with dark lines and small pores (5-8 pores/mm) and basidiospores (4-5 × 3.5-5 µm), and is found on dead trunks of Swietenia mahagoni (L.) Jacq. in Cuba (Murrill 1915; Lowe 1957; Larssen & Coob-Poulle 1990). When Murrill (1915) described this species he designated two type specimens which are F. S. Earle & W. A. Murrill 545 (NY 776502) as the holotype and J. K. Brace 4389 (NY 985681) as the paratype. Only the holotype of F. swieteniae has been used for morphological revisions and comparisons in subsequent works (Lowe 1957; Salvador-Montoya et al. 2022). Consequently, Salvador-Montoya et al. (2022) synonymized F. swieteniae within F. cedrelae (Murrill) Murrill based on morphological (holotype comparisons), molecular, and ecological data.

Additionally, during a study of FulvifomesMurrill species, we revised the paratype of F. swieteniae designated by Murrill in 1915. For macro-morphological observations, the size, shape, and color of the basidiomata (pileal surface, context, tubes and dissepiments), as well as characteristics of the tubes and pore surface (number of tube layers and pores per millimeter), were observed. Colors were determined following Kornerup & Wanscher (1978). Microscopic examination was performed on freehand sections of specimens mounted in water, 5% potassium hydroxide solution (KOH), and Melzer’s reagent (IK) (following Ryvarden 1991). All microscopic measurements (n = 40) and drawings were made in KOH. When giving the size range of the microscopic elements, 5% of the measurements were excluded from each end and are given in parentheses. To describe the hyphal system, sections of the tube trama and context of the basidiomata were carefully dissected under a stereomicroscope after incubation in 5% (v/w) sodium hydroxide solution (NaOH) for 48h at 40 °C (see Drechsler-Santos et al. 2016), and examined under optical microscopy.

The specimen NY 776502 (holotype of F. swieteniae) presents a context with dark lines, a pore surface with 5-6 pores/mm, a hyphal system that is a monomitic in the context and dimitic in the tubes, a hymenium without setae and subglobose to broadly ellipsoid basidiospores with a flattened side (4.5-5.5 × 3.5-4.5 µm) that are thick-walled and yellowish and become darker in KOH solution. However, the specimen NY 985681 (paratype of F. swieteniae) has a context without dark lines, a pore surface with 6-7 pores/mm, a hyphal system that is a monomitic in the context and dimitic in the tubes, a hymenium with subulate to ventricose hymenial setae (20-35 × 6-7 µm), and subglobose to broadly ellipsoid basidiospores with a flattened side (5.5-6 × 4.5-5 µm) that are thick-walled and yellowish and become darker in KOH solution.

Based on our results, the specimen NY 776502 fits the morphological concept of Fulvifomes. This genus is characterized by a context with or without dark lines, a monomitic to dimitic hyphal system, absence of setae, and subglobose to ellipsoid and colored basidiospores, occasionally with a flattened side that become darker in KOH solution (Wagner & Fischer 2002; Zhou 2014; Drechsler-Santos et al. 2016; Salvador-Montoya et al. 2018a). However, unlike the holotype of F. swieteniae (NY 776502), the specimen NY 985681 (paratype of F. swieteniae) presents different characteristics to a Fulvifomes species such as hymenial setae (Fig. 1).

Species with a hyphal system that is monomitic in the context and dimitic in the tubes, hymenial setae and colored basidiospores are present in Tropicoporus L.W. Zhou, Y.C. Dai & Sheng H. Wu and Sanghuangporus Sheng H. Wu, L.W. Zhou & Y.C. Dai (Zhou et al. 2016; Wu et al. 2022). Based on a reappraisal of the literature, we noted that specimen NY 985681 fits the morphological concept of Tropicoporus linteus (Berk. & M.A. Curtis) L.W. Zhou & Y.C. Dai. Currently, T. linteus is characterized by perennial basidiomata with a context without dark lines, a pore surface with 5-7 pores/mm, a hyphal system that is monomitic in the context and dimitic in the tubes, hymenial setae that are ventricose or subulate (22-30 × 4-7 μm), and subglobose to broadly ellipsoid (4.8-5.5 × 3.9-4.6 μm) thick-walled, yellowish basidiospores (Dai & Xu 1998; Tian et al. 2013; Wu et al. 2022). In addition, T. linteus is distributed in Central America and the Caribbean (Tian et al. 2013; Zhou et al. 2016; Wu et al. 2022), and correlatively, specimen NY 985681 was collected in the Bahamas.

Figure 1
a-b. Morphological features of the specimen NY 985681 (paratype of F. swieteniae) - a. basidioma; b. ventricose hymenial setae. Scale bars: a = 2 cm; b = 10 µm.

Basidiospores with a flattened side that become darker in KOH solution are observed in specimen NY 985681. In Tropicoporus, T. drechsleriSalvador-Montoya & Popoff presents these characteristics (Salvador-Montoya et al. 2018b). However, T. drechsleri has a dark line in the context (Salvador-Montoya et al. 2018), whereas the dark line is absent in specimen NY 985681 (Fig. 1). Therefore, based on the results of this work, and a reappraisal of the literature, specimen NY 985681 is determined as T. linteus and must not be considered as the paratype of F. swieteniae. Furthermore, we emphasize the importance of the detailed shape of the basidiospores, and the reaction of the basidiospore wall in KOH solution as well, to describe species in Tropicoporus.

Material examined: Fulvifomes cedrelae: Cuba, Alto Cedro, Santiago de Cuba, on Swietenia mahagoni, 19-20.III.1905, F.S. Earle & W.A. Murrill 545 (NY 776502!, as holotype of F. swieteniae). Tropicoporus linteus: Bahamas, Acklin’s Island, Gold Rock, 21.XII.1905-6.I.1906, L J.K. Brace 4389 (NY 985681!, as paratype of F. swieteniae).

Acknowledgements

We thank the curator of NY herbarium, for providing access to collections; and Genevieve Gates, for the revision in the English language. The first author and Elisandro R. Drechsler-Santos (process no. PQ 310150/2022-1) thank Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Conselho Nacional de Desenvolvimento Científico y Tecnológico (CNPq), for financial support in this work, respectively. This research is part of PROTAX (FAPESC 2021TR390, CNPq 441821/2020-0), under studies of MIND.Funga Research Group: http://mindfunga.ufsc.br/

Data availability statement

In accordance with Open Science communication practices, the authors inform that there is no data sharing of this manuscript.

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Publication Dates

• Publication in this collection
  19 July 2024
• Date of issue
  2024