Phytotaxa 619 (2): 182–188 https://www.mapress.com/pt/ Copyright © 2023 Magnolia Press ISSN 1179-3155 (print edition) Article PHYTOTAXA ISSN 1179-3163 (online edition) https://doi.org/10.11646/phytotaxa.619.2.6 On the identity and distribution of Ischaemum flumineum (Poaceae: Andropogoneae) in India SHAHID NAWAZ LANDGE1* & RAJENDRA D. SHINDE2 1 The Blatter Herbarium (BLAT), St. Xavier’s College (Autonomous) Mumbai 400001. � shahidnawaz.landge@xaviers.edu; https://orcid.org/0000-0002-6734-6749 2 St. Xavier’s College (Autonomous) Mumbai 400001. � rajendra.shinde@xaviers.edu; https://orcid.org/0000-0002-9315-9883 *Corresponding author Abstract While investigating the identity and distribution of Ischaemum flumineum, we encountered a lack of holotype designation by Bor. Consequently, we took the initiative to designate a lectotype, selecting a specimen from the Kew herbarium. To facilitate a comprehensive understanding, we conducted a brief review of the variable characteristics of I. timorense and I. thomsonianum, drawing on insights from “Grasses of China” and “Grasses of Malaysia” in addition to “Grasses of India”. While these species are the closest relatives to I. flumineum, none of their variable forms exhibit the distinctive basal indumentum found in the latter. To aid in precise differentiation among these three species in India, we revised the key, providing an improved tool for identification. Furthermore, we discussed the distribution of I. flumineum in India with the help of a map, based on the available specimens at BLAT, DD and K herbaria. Key words: Gramineae, Ischaemineae, Ischaemum timorense, Ischaemum thomsonianum, Taxonomy Introduction Ischaemum Linnaeus (1753: 1049) is taxonomically one of the most complex genera in the tribe Andropogoneae. Currently, the genus comprises 87 species worldwide, of which 63 are exclusively found in India. Among these, 43 species appear to be endemic (Landge & Shinde, 2022a). While studying the genus Ischaemum at the Blatter Herbarium (BLAT), the first author (SNL) discovered an intriguing specimen from Madras, Tamil Nadu. Using Bor (1960) as a reference, we identified it as a good match for I. flumineum Bor (1949: 572). Furthermore, confirmation on the identification was obtained by studying the protologue and comparing the identified specimen with the type materials procured as high-resolution digital images from Kew (K) & Dehra Dun (DD) herbaria. Ischaemum flumineum is an obscure species with a confined distribution range in the states of Karnataka and Tamil Nadu. In Indian grass literature, except for the protologue, no information is available, and perhaps no specimen was collected after the type materials. Sebastine (1962) included this species as an addition to the flora of Madras Presidency but did not cite any personal collection. He gave a direct reference to Bor (1949). The only other collection of this species that exists is by “Hallberg & McCann s.n.” housed at the Blatter herbarium, but it antedates the type specimen by 18 years as it was collected in October 1919 from the type locality Gersoppa Falls (also known as Jog Falls), North Kanara, Karnataka. This specimen was identified and confirmed by Bor himself at Kew Herbarium as “Ischaemum flumineum Bor,” certainly after describing the species. The specimen is well-preserved and exhibits a characteristic Goldenish-yellow indumentum at the base (Fig. 2, C). The term ‘flumineus’ is applied to plants that grow in running streams. The epithet ‘flumineum’, originating from Latin, literally translates to ‘river’. In this sense, it means ‘growing near water’ (Clifford & Bostock, 2007). The remark on the type sheet at K clearly reads as “Growing in the rocky beds and clefts in the rushing of the river”. 182 Accepted by Arjun Tiwari: 23 Sept. 2023; published: 6 Oct. 2023 Materials & Methods The present study is based on specimens of Ischaemum flumineum housed at the Blatter Herbarium (BLAT). The issue concerning its identity and distribution has been there in grass literature, and various Indian herbaria such as BLAT, BSI, CAL, DD, BAMU, JCB, K, MH, and WCAS were consulted for the relevant specimens (acronyms according to Thiers 2020 continuously updated). However, apart from BLAT, DD, and K, none of the herbaria housed the specimens. During the investigation of its taxonomic identity, it was noted that Bor (1949) did not explicitly designate a holotype. Consequently, we designated a lectotype based on a specimen at the K herbarium. The first author (SNL) conducted numerous field explorations since 2019 in the Western Ghats of Maharashtra to collect Ischaemum flumineum but was unable to obtain any specimen. The only collection of this species, aside from the type, is the one labeled as “Hallberg & McCann s.n.” at BLAT. This particular specimen proved to be very helpful in understanding the taxonomic characteristics of this species. Lectotypification of the name Ischaemum flumineum Bor (1949: 572) [Fig. 1]. FIGURE 1. Type specimens of Ischaemum flumineum Bor. A. Lectotype (n. L. Bor 11390 at K). B. Syntype (n. L. Bor 77265 at DD). (© The Board of Trustees of the RBG, Kew & The Director, DehraDun Herbarium, Uttarakhand (DD). Lectotype (hic designatus):—INDIA. Bombay [erstwhile Bombay Presidency], Jog [Gersoppa], 28 April 1937, n. L. Bor 11390 (K barcode K000245740 [digital image!]); syntype: Madras, Coimbatore, Top slip, November 1937, n. L. Bor 77265 (DD [digital image!]). Note: Bor (1949) described Ischaemum flumineum based on the collections he cited as follows: “INDIA. Bombay: Jog, 28 April 1939, n. L. Bor 11390 (Typus in Herb. Kew. et in Herb. Dehra Dun.); Madras: Coimbatore, Top Slip, Nov. 1937, n. L. Bor s.n.” Apparently, he did not intend to designate a holotype, as he indicated the type to be in two different herbaria, i.e., K and DD. We also checked the CAL and MH herbaria for the presence of the type specimens, but they did not have the type specimens. However, when we consulted the concerned authority at the DD herbarium, ISCHAeMuM fLuMIneuM IN INDIA Phytotaxa 619 (2) © 2023 Magnolia Press • 183 they denied the presence of any specimen belonging to “n. L. Bor 11390”. Instead, the specimen they had was labeled as “n. L. Bor 77265” from Top Slip, Coimbatore, collected in November 1937. In the protologue, Bor’s cited specimen from Coimbatore lacked a collection number, which seems to be an error during typing, because based on the original information, no specimen was found at CAL, DD, K, and MH herbaria. This error of erroneous type citation may be corrected under the Art. 9.2 (Turland et al. 2018). Thus, the material from DD labeled as “n. L. Bor 77265” is an original type specimen. In the absence of any holotype designation by the original author, all the cited specimens that are from two different gatherings are considered syntypes, according to Art. 9.6 (Turland et al. 2018). From these specimens, a lectotype may be designated by following the Art. 9.3 (Turland et al. 2018). Here, we have selected a specimen “n. L. Bor 11390” at K as a lectotype for the name Ischaemum flumineum, but its duplicate at DD could not be traced or is perhaps lost, if it is traced in future should to be called an isolectotype. The other cited material, “n. L. Bor 77265”, from a different gathering which is housed at the DD herbarium, is a syntype. Distrbution:—Karnataka and Tamil Nadu, South India (Fig. 3). Hitherto, endemic to Peninsular India. FIGURE 2. Characteristics of Ischaemum flumineum Bor. A. Habit. B. Sessile spikelet showing wingless keel of the upper glume. C. Goldenish-yellow indumentum present at the base of the plant. (Based on Hallberg & McCann s.n. at The Blatter Herbarium (BLAT)). © The Blatter Herbarium, Mumbai. 184 • Phytotaxa 619 (2) © 2023 Magnolia Press LANDGE & SHINDE FIGURE 3. Distribution of Ischaemum flumineum Bor in India based on the valid specimens housed at BLAT, DD and K herbaria. (Abbreviations: K: Karnataka state; TN: Tamil Nadu state). Discussion Taxonomic identity of Ischaemum flumineum Ischaemum flumineum is characterized by prominently ribbed recurved naviculate cataphylls at the base. The basal sheaths are provided with yellowish indumentum. The leaf blades narrow at the base, resembling a pseudo-petiole. The nodes are densely bearded, and the lower nodes exhibit rooting and branching, forming a complex branch system. The culms are terete, while the peduncle is highly exserted. The racemes are short and binate, with a golden yellow glistening indumentum throughout. The lower glume is coriaceous below and herbaceous above, with notable yellowish hairs on the dorsal surface. The apex of the lower glume is characteristically bi-cuspidate. The upper glumes of the spikelets lack wings and have a long arista (midrib) emerging between a slight notch. The geniculate awn measures approximately 18 mm. ISCHAeMuM fLuMIneuM IN INDIA Phytotaxa 619 (2) © 2023 Magnolia Press • 185 Bor (1949) described Ischaemum flumineum based on his personal collections from Jog (Karnataka) and Coimbatore (Tamil Nadu). It appears that he did not collect any specimens from Maharashtra. In his description, Bor (1949) compared Ischaemum flumineum with I. timorense Kunth, stating that the former predominantly differs in the perennial habit and having a bi-cuspidate lower glume of the sessile spikelet (Figs. 1 & 2). Later, in 1960, he placed the former species close to the perennial form of I. thomsonianum in the key differentiating it based on wiry habit, upper glume of the sessile spikelet without a wing, and, most importantly, a hairy base of the plant. The color of the basal hair is unique and characteristic of this species, somewhat glistening yellow or pale golden yellow. Similar-colored hairs are also associated with the lower glume, callus, rhachis internode, and pedicel. Two other known species in the genus with characteristic basal hairs are I. mistryi Landge & R. D. Shinde (2021b: 273) and I. amethystinum J. P. Lebrun that are endemic to India and Africa respectively, but the hairs in those species are whitish, also somewhat purplish in the latter. Indeed, in many Andropogoneae grasses such basal hairs present a potential character for species delimitation. To mention a few species such as, Parahyparrhenia bellariensis (Hackel 1885: 123) Clayton (1972: 448), Lophopogon kingii Hooker (1896: 149), Sehima galpinii Stent, many eulalia Kunth species with basal indumentum, eremopogon foveolatus Stapf (1917: 183), Chrysopogon aucheri Stapf (1907: 211), etc. More details on the first species can be found in Landge & Shinde (2021a, 2022b). Ischaemum flumineum can be easily confused with I. timorense, one of the most complex and phenotypically plastic species in the genus widespread in the tropics and subtropics of South East Asia. According to the traditional key used to differentiate species in the genus in India, I. flumineum is likely to be misidentified as I. timorense. Bor’s (1949) understanding of the perennial habit and bicuspidate apex of the lower glume of the sessile spikelet—the characters that he used in the key exclusively to differentiate I. flumineum from allied species, was not comprehensive, as these characters are also found in I. timorense in China. The only reliable character that appears to distinguish I. flumineum from other allied taxa is the yellowish basal indumentum. In the Flora of China eFloras (2008), Ischaemum timorense and I. thomsonianum Stapf ex C. E. C. Fischer (1934: 1722) were separated from two other closely allied species I. ciliare Retz. and I. polystachyum J. Presl by having the lower glume of sessile spikelets not winged on the keels and apex sharply bicuspidate. Further, I. timorense was distinguished from I. thomsonianum as having “spikelets more or less glabrous; upper glume of sessile spikelet not winged.” Potdar et al. (2012) distinguished Ischaemum timorense by its smaller spikelets measuring from 2.5 to 3.0 mm long and the apex of the lower glume of the sessile spikelet, which is not bicuspidate. In contrast, I. thomsonianum was mentioned to possess spikelets that are larger in size, ranging from 5.0 to 6.0 mm long, and a bicuspidate lower glume. However, it should be noted that these distinguishing characters may not be consistently applicable in a broader context, as there exists a fairly large proportion of specimens displaying variations within both species. Jansen (1953) made an observation about Ischaemum timorense in Malaysia, noting that it can be annual in the first year of flowering, resulting in very slender and weak forms growing up to 30 cm high, with two racemes measuring 2.0 cm long. Consequently, spikelets from these specimens are expected to be smaller. On the other hand, certain forms of I. timorense appear robust, reaching heights of up to 1.0 m. For instance, Jansen cited the specimen “Dorgelo 1813,” likely to have been collected from Indonesia, where racemes are 8.0 to 10 cm long. In these cases, the spikelets from these specimens are expected to be larger. Importantly, Jansen emphasized that the lower glume in I. timorense is distinctly bicuspidate. This observation is in alliance with that of eFloras (2008). We conclude, based on the above observations that the character of a bicuspidate lower glume of the sessile spikelet cannot be used to segregate either species, as it is highly variable. The only good character that seems to differentiate I. thomsonianum is a winged upper glume. We have revised a key to identify the three closely allied species as follows: Revised key to differentiate closely allied species to Ischaemum flumineum 1. 1. 2. 2. Base of the plant with distinct goldenish-yellow indumentum (caducous in mature specimens) ........................................................ ................................................ I. flumineum (Note: upper glume of the sessile spikelet consistently devoid of a wing on the keel) Base of the plant glabrous ..................................................................................................................................................................2 Keel of the upper glume of the sessile spikelet distinctly winged .......................................................................... I. thomsonianum Keel of the upper glume of the sessile spikelet not winged .............................................................................................I. timorense As is evident in the key, in the absence of the basal portion of the specimen, it could lead to significant confusion regarding whether to assign it to Ischaemum flumineum or I. timorense. This is because in both cases, the keel of the upper glume of the sessile spikelet lacks a wing. The yellowish hairs on the raceme of the former might not always be consistently useful, as in the type specimen at K, somewhat whitish hairs are observed. 186 • Phytotaxa 619 (2) © 2023 Magnolia Press LANDGE & SHINDE There is a doubt regarding the identity of Ischaemum flumineum in Kabir & Nair (2008). They used a character of rudimentary geniculate awn measuring between 1.0 to 3.0 mm in the key to differentiate I. flumineum from all the other congeners. However, later in the description, they contradicted themselves by mentioning the size of the awn as approximately 13 mm and 10 mm for the sessile and pedicelled spikelets, respectively. In the type specimens at K and DD herbaria, the awns measure approximately 15 mm (Fig. 1). The derivation of the key character of the rudimentary awn used by Kabir & Nair (2008) has a perplexing origin and does not align with the type specimens, where the awns are fairly well developed. In their description, they mentioned the apex of the lower glume of the sessile spikelet as ‘bifid or mucronate’. According to Bor (1960), the lower glume in I. flumineum is always bi-cuspidate (Fig. 2, B). The mention of a mucronate apex of the lower glume by Kabir & Nair (2008) asserts the plant to be I. timorense. In I. timorense apex of the lower glume of the sessile spikelet could be variable from mucronate to bicuspidate. To draw any firm inference around its correct identity, a specimen is required. The extensive phenotypic plasticity observed in Ischaemum timorense and I. thomsonianum warrants a dedicated and comprehensive research paper to thoroughly discuss and explore this intriguing aspect. In this context, it is essential to include I. polystachyum J. Presl, in the investigation. This species is widely recognized for its remarkable morphological variations observed in South and South East Asia, as well as the Far East. Addressing the phenotypic plasticity in these three species will undoubtedly contribute to a deeper understanding of their biology, ecology, and taxonomic relationships. Such an investigation could potentially shed light on the factors influencing their morphological diversity and aid in refining their classification and identification. By conducting a separate and thorough study focusing on the phenotypic plasticity of these species, we can uncover valuable insights that may not only enhance our knowledge of the genus Ischaemum but also contribute to the broader understanding of plant variability and adaptation. Note on the distribution of Ischaemum flumineum in India Sur (2001) did not include Ischaemum flumineum in the key to differentiate species in the genus from India. However, he provided a description with an error in citing the type locality. Instead of Karnataka for Jog, he mistakenly wrote Maharashtra. This mistake also appeared in the distribution, so much magnified so that he only mentioned Maharashtra. This error was later repeated in the updated revisionary work by Srivastava & Nair (2010) and in the checklist of Indian grasses by Kellogg et al. (2020). Additionally, they added a new locality, the Andaman Islands, without providing any reference to the published literature or existing herbarium collections. Upon close examination, it becomes evident that the basal indumentum serves as a distinctive feature unique to Ischaemum flumineum. Interestingly, this characteristic is not observed in any of the variable forms of I. timorense and I. thomsonianum. While Singh & Rao (2008) may have overlooked this critical feature, leading to their decision to synonymize I. flumineum under I. timorense, we firmly disagree with this treatment. Our analysis and findings support the notion that I. flumineum should be recognized as a separate and distinct species, and we maintain this classification unless molecular evidence suggests otherwise. Based on the valid specimens studied at BLAT, DD and K herbaria, it seems that Ischaemum flumineum, so far, is only known from Gersoppa falls in Karnataka and Coimbatore in Tamil Nadu, South India (Fig. 3). The reports on the occurrence of this species in Maharashtra and Andaman Islands or elsewhere are uncertain. However, an arduous quest is anticipated in the rugged riparian habitats thwart the adjoining state of Kerala where the prospect of its presence is promising. Acknowledgements We would like to thank Directors and Curators of BLAT, BSI, CAL, DD, K & MH herbaria for their active cooperation during this work. We are also thankful to the authorities of St. Xavier’s College (Autonomous) for supporting this work, providing us the workplace and library facilities. 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