Revisiting the tangled taxonomy of Scleria subgenus Scleria section Hymenolytrum: a lectotype replacement, a new synonym, and the reestablishment of Scleria cyperinoides as an accepted name

Abstract

During a taxonomic investigation of the names classified under Scleria subgenus Scleria section Hymenolytrum, it was necessary to replace the lectotype of S. macrogyne, as the specimen does not agree with the original description. In addition, we propose S. ramosa as a new synonym of S. macrogyne and discuss the reestablishment of S. cyperinoides as an accepted name.

Keywords:
Nomenclature; nut rushes; Sclerieae; sedges; taxonomy

Introduction

Scleria P.J.Bergius is one of the largest genera of Cyperaceae Juss., with about 260 species (Larridon 2022). It is recognized as monophyletic and subdivided into four subgenera and 17 sections (Bauters et al. 2016; 2018). Among the recognized sections, Scleria subgenus Scleria section Hymenolytrum (Schrad. ex Nees) Core currently includes 15 species (Bauters et al. 2016). These species have many morphological similarities such as scabrous and/or sharp stems and leaves, winged sheaths, membranous appendage on the contraligule, densely branched paniculate inflorescence among others. Some useful characteristics to recognize the species (i.e., winged sheaths, trichome ligule, and hypogynium shape) are not mentioned in the original descriptions, are treated ambiguously, or are not easily visualized in the photographs of the nomenclatural types available online, causing problems in their delimitation. During the study of the flora of Scleria in Pará state, Brazil (Schneider & Gil 2021), and the Scleria monograph in the Flora do Brasil 2020 project (Schneider & Gil 2020), the importance of developing a taxonomic investigation with this section was recognized to clarify some taxonomic and nomenclatural issues. Here, we present some results of this investigation, highlighting the need for the lectotype replacement of Scleria macrogyne C.B.Clarke, proposing S. ramosa C.B.Clarke as a new synonym of S. macrogyne, and reestablishing S. cyperinoides C.B.Clarke as an accepted name.

Material and methods

The taxonomic revision was carried out through the original descriptions and by consultation of nomenclatural types and other specialized literature cited in the species comments. Herbaria were consulted by loans (K and NY) or virtually (B, LD, P); when necessary, direct contacts were made with the curators. The acronyms and the virtual herbarium websites follow Thiers (2023). Nomenclatural decisions follow Turland et al. (2018). Images of the fruits were taken using a stereoscopic microscope Leica M205A.

Results and Discussion

Scleria macrogyne C.B.Clarke, Bull. Misc. Inform. Kew, Addit. Ser. 8: 59. 1908. Type: [GUYANA] BRITISH GUIANA. [Mazaruni River] Massaruni River, Aug. 1889, Jenman 6088 (lectotype [designated here]: K [barcode K001081684]! Figure 1; isolectotype: NY [barcode NY00021645).

Figure 1.
Replacement lectotype of Scleria macrogyne C.B.Clarke (Jenman 6088 - K [K001081684]). Image: © The Board of Trustees of the RBG, Kew (United Kingdom).

Originally cited syntypes: Parker s.n. (K [barcode K001081681]!), Appun 448 (K [barcode K001081683]!), Jenman 2463 (K [barcode K001081682]!), and Jenman 6088 (NY [barcode NY00021645]!, and K [barcode K001081684]!) - Scleria macrogyne; Ule 6065 (G [barcode G00098567!, L [barcode L0042773]!, and K [barcode K001081680]!) - Scleria cyperinoides; Gardner 2985 (BM [barcode BM000629129]!, K [barcode K000189713]!, and K [barcode K000189714]!) - Scleria martii (Nees) Steud.

= Scleria ramosa C.B.Clarke, Bull. Misc. Inform. Kew, Addit. Ser. 8: 59. 1908, syn. nov. Type: BRAZIL. Sine loco, s.d., Burchell 8413 (holotype: K [barcode K001081679]! Figure 2).

Figure 2.
Holotype of Scleria ramosa C.B.Clarke (Burchell 8413 - K [K001081679]). © The Board of Trustees of the RBG, Kew (United Kingdom).

Scleria macrogyne C.B.Clarke was described based on six syntypes from different countries and localities, four of them collected in Guyana (Parker s.n., Appun 448, Jenman 2463 and Jenman 6068 - Fig. 1) and two in Brazil (Gardner 2985 and Ule 6065 - Fig. 3). Clarke (1908) described it as a robust plant with a scabrous stem at the angles, winged sheaths with an appendage on the contraligule, leaf-blades 40‒50 × 1 cm, scabrous on the margins, inflorescence paniculate and dense, pilose rachis, smaller panicles below the terminal panicle, numerous staminate spikelets 5‒6 mm in length, ferruginous or chestnut-colored glumes, pistillate spikelets 10 mm long, fruit 3 mm long, oval-acuminated, with a slightly reticulate and pubescent surface, thin hypogynium, with yellowish lobes, patent and with a crenate-subdentate apex. Clarke (1908) compared S. macrogyne with S. martii, the latter having a more robust inflorescence. However, when analyzing the syntypes of Scleria macrogyne, it was possible to recognize that some of them do not correspond to the same species, and consequently, some specimens do not agree with the original description. Charpin et al. (1993) designated specimens preserved in herbarium G as the lectotypes for some Cyperaceae names, and thus elected Ule 6065 (G [barcode G00098567]) as the lectotype of S. macrogyne. However, Ule 6065 has some taxonomic relevant characteristics that are very distinct from the original description of S. macrogyne, such as the vinaceous glumes of the spikelets (Fig. 3) and the erect and fimbriate lobes of the hypogynium (Fig. 4 K and M) (ferruginous or chestnut-colored glumes and patent and crenate-subdentate hypogynium lobes in the S. macrogyne original description). In addition, the specimen Ule 6065 is distinguished from the other syntypes by not having a ligule of trichomes, a feature not cited by Clarke (1908), but taxonomically important among the species of Scleria (Camelbeke & Goetghebeur 1999; Schneider & Gil 2021)

Figure 3.
Previous isolectotype of Scleria macrogyne C.B.Clarke (Ule 6065 - K 10 [K001081680]). Image: © The Board of Trustees of the RBG, Kew (United Kingdom).

Figure 4.
Lectotype of Scleria cyperinoides C.B.Clarke (Spruce 1252 - K [K000584483]). Image: © The Board of Trustees of the RBG, Kew (United Kingdom).

Among the remaining syntypes, Gardner 2985 (BM, K) has a smooth stem, apterous sheaths, and hypogynium with erect lobes (Fig. 4 I -J) (vs. scabrous stem at the angles, winged sheaths, and hypogynium with patent lobes in the S. macrogyne original description). Parker s.n. (K) (Fig. 4 G , -H) with vinaceous glumes also differs from the ferruginous or chestnut-colored glumes described in the original description of S. macrogyne. Thus, under the main characteristics described by Clarke (1908), only three syntypes remain: Appun 448 (K) (Fig. 4 E -F), Jenman 2463 (K) (Fig. 4 C -D), and Jenman 6088 (Fig. 4 A -B). As the previously designated lectotype is conflicting (Charpin et al. 1993), and other nonconflicting original material remains, we selected Jenman 6088 (K) as a replacement lectotype (art. 9.19 of ICN, Turland et al. 2018). This specimen is best conformed to the name description and still has a duplicate in the NY herbarium.

By replacing the lectotype of Scleria macrogyne, Scleria ramosa C.B.Clarke would appear as a synonym of this name, because when analyzing the types of both names, the characteristics highlighted in S. ramosa are not exclusive for its maintenance as an accepted name.

Scleria ramosa was described as a robust species with winged sheaths, leaves 20‒30 × ca. 1 cm, panicle ca. 10 × 7 cm, with rachis slightly pubescent, stramineous or chestnut glumes, fruit 2 mm long, with narrow-apiculate apex, rarely acute, stramineous to brownish, hypogynium obconic, truncate, almost the same color as the fruit (Clarke 1908). What is remarkable in the original description is that the plant fragment analyzed in the Burchell 8413 has a stem with five branches, four of these with terminal panicles (Fig. 2). However, when examining this specimen, the hypogynium shows triangular lobes with crenate or subdentate apex, as described in S. macrogyne. Depending on the angle of analysis, the hypogynium apex can be mistaken as truncate and even described as annular. Furthermore, stem branching and the number of panicles can be a variable character state depending on the environment. When collecting specimens of Scleria subgenus S. section Hymenolytrum, some species have a branched stem and a higher number of panicles related to the solar incidence in forest edges or clearings, as in S. secans (L.) Urb. and S. stipularis Nees. Therefore, after analyzed the types of the names mentioned, and verified the morphological features overlaping (e.g. winged sheaths, a ligule of trichomes, a membranaceous appendix of the contraligule and hypogynium with laciniate lobes), we propose here Scleria ramosa as a heterotypic synonym of S. macrogyne.

Scleria cyperinoides C.B.Clarke, Bull. Misc. Inform. Kew, Addit. Ser. 8: 61. 1908. Type: BRAZIL. [Amazonas], [Manaus] “Barra”, Jan. 1851, Spruce 1252 (lectotype [designated by Camelbeke et al. 2000]: K [barcode K000584483]! Figure 5, isolectotypes: LD [access LD1621288] photo!, NY [barcode NY00021646]!, P [barcode P00274193] photo!, P [barcode P00274194] photo!).

Figure 5.
Nutlets in lateral and basal views, highlighting the hypogynies. Scleria macrogyne, A and B: Jenman 6065. Scleria macrogyne, C and D: Jenman 2463. Scleria macrogyne, E and F: Appun 448. Scleria macrogyne, G and H: Parker s.n. Scleria martii, I and J: Gardner 2985. Scleria cyperinoides, K and M: Ule 6065. Scleria cyperinoides, L and N: Spruce 1252. Image: © The Board of Trustees of the RBG, Kew (United Kingdom). Scale: 1 mm.

Originally cited syntypes: Vaughan 28 (K [barcode K001081672]), Spruce 1252 (K [barcode K000584483], LD [access LD1621288], NY [barcode 00021646], P [barcode P00274193], and P [barcode 00274194]), and Burchell 9789 (K [barcode K001180336]).

According to Clarke (1908), Scleria cyperinoides was described as a robust plant, leaves with 20‒60 × ca. 1 cm, winged sheaths with membranous appendix at the apex of the contraligule, and scabrous margins, inflorescence with 18 × 12 cm, terminal panicle with 5 × 4 cm, reddish and slightly pilose rachis, staminated spikelet with 3‒4 mm long, blood-brown, pedicels 5 mm long, pistillate spikelet ca. 6 mm long, ovoid and long-lanceolate apex, fruit 2.5 mm long, obscurely triangular in cross-section, slightly sparse-pilose, purplish-dark hypogynium, lobes with whole teeth of the same color (Fig. 4 L -N). In this description, Clarke (1908) compared this species with others from Scleria subg. S. sect. Schizolepis (Schrad. ex Nees) C.B.Clarke due to the shape of the hypogynium with deep lacinia (present in most species of this section), as opposed to S. cyperina Willd. ex Kunth (a species compared by Clarke), which presents entire lobes. Clarke (1908) cites three syntypes, all collected in Brazil, two in the North, Vaughan 28 and Spruce 1252, and one in the South, Burchell 9789. Therefore, Camelbeke et al. (2000) designated Spruce 1252 (Fig. 5), kept in K, as a lectotype of S. cyperinoides. The designated specimen is consistent with the original description.

In the Scleria flora of Bolivia, Camelbeke et al. (2003) synonymized S. cyperinoides under S. martii, the latter described as a species with winged sheaths. However, Nees (1842) in the original description of S. martii does not cite winged sheaths and this structure is not observed in the illustration of the species, provided in the protologue and also on the holotype (M [barcode M-0010466] photo!). Concerning this structure, Core (1936) distinguished S. martii and S. violacea from S. cyperinoides and S. macrogyne because the first two are species with apterous sheaths, while the latter two are winged. Even with these striking differences, the synonymization of S. cyperinoides was followed by other authors, confusing the recognition of S. martii (BFG 2015; Schneider & Gil 2020; POWO 2023). Besides the morphology, S. cyperinoides also differentiates by being a species of shaded environments (underwood), with a closed canopy, while S. martii occurs in open environments, such as forest edges and clearings. Thus, we understand that S. cyperinoides is a different species from S. martii and should no longer be a heterotypic synonym. Here, we are reestablishing S. cyperinoides as an accepted name in Scleria subgenus S. section Hymenolytrum.

Acknowledgements

We thank the CAPES/Brazil for LJCS’s scholarship grant (88887.633240/2021-00); the CNPq/Brazil for ASBG’s and AOS´s productivity grants (314271/2020-1 and 315192/2021-6); the CNPq and FAPESPA/Pará/Brazil (PRONEM - 052/2021) for financial support; the curators of the herbaria for providing loans, information or images (B, K, LD, NY, and P); the COCTE-MPEG for the photographs of the fruits. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.

References

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Edited by

Editor-in-Chief:

Thaís Elias Almeida

Associate Editor:

Nádia Roque

Publication Dates

• Publication in this collection
  07 June 2024
• Date of issue
  2024

History

• Received
  13 Sept 2023
• Accepted
  10 Dec 2023