ABSTRACT Ooia rhea and O. stygis are described as new species from, respectively, Paleogene shales in Kalimantan Utara and Palaeogene granites in Kalimantan Barat, Indonesian Borneo, and together taking the genus to fourteen species. A comparative figure of the spadix, the definitive means to delimitate species, of all species is provided and both proposed novelties are illustrated from living plants.

Two new species of Hanguana (Hanguanaceae), H. ensifolia and H. flavescens, from western Sarawak are described and illustrated here. This brings the total number of species in Borneo to eleven. Detailed descriptions and colour plates for both species are provided, with additional notes on their ecology, distribution, and conservation status. A key to Hanguana in Borneo is provided. Affinities to morphologically similar species are also discussed.

Based on published molecular analyses combined with morphological data, the genus Schismatoglottis is restricted to species with hapaxanthic shoots and a caducous spathe limb shed almost always in a single piece. Thus defined, Schismatoglottis comprises sixty-nine accepted species, twenty-four provisionally accepted names, and three species of doubtful affinity [Schismatoglottis conoidea, S. convolvula, and S. priapica] that are retained provisionally in Schismatoglottis pending further study. Eight-five species hitherto assigned to Schismatoglottis with pleionanthic shoots and spathe limbs variously senescing are transferred into seven new genera: Aia (monotypic), Ayuantha (four species), Bau (26 species), Borneoa (22 species), Ibania (12 species), Sarawakia (five species), and Tweeddalea (15 species). All genera are illustrated, together with representative species of Schismatoglottis s.s., and a species-finder list provided as an Appendix. The changes presented here take the vascular plant Bornean flora to 1601 native genera.

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods(1,2). A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome(3,4). Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins(5-7). However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes(8). This 15-fold increase in genus-level sampling relative to comparable nuclear studies(9) provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade.

(3048) Stylochiton Lepr. in Ann. Sci. Nat. Bot., ser. 2, 2: 184. 1834 ('Stylochæton') [Angiosp./Ar.], nom., orth. et gen. masc. cons. prop. Typus: S. hypogeus Lepr. ('hypogeum'). Stylochiton is a not very large genus of about 25 species of (sub)tropical African aroid geophytes whose particular botanical and evolutionary significance may be said to lie in their genus's near "basal" position in the almost entirely monoecious subfamily Aroideae (see, e.g., Haigh & al. in Amer. J. Bot. 110: e16117. 2023). They present features, nearly unique in the subfamily, which accord to greater or lesser degree with aspects of the floret morphology of most of the earlier diverging bisexual-floreted subfamilies, including a perianth-like structure around the pistils and male florets which furthermore have the stamens with distinct thread-like filaments. The spelling and gender of masculine, etymologically correct Stylochiton vs. the original neuter, etymologically erroneous Stylochaeton remain an unresolved source of nomenclatural ambiguity 40 years after a proposal similar to this one (Nicolson & Mayo in Taxon 33: 509. 1984) led to no properly decisive nor linguistically plausible recommendation either way. Leprieur (in Ann. Sci. Nat., Bot., ser. 2, 2: 184–186. 1834) established the name with the spelling Stylochaeton and attributed neuter gender to it. He explicitly intended the name to allude, aptly, to an indusium around the style (i.e., the characteristic cupular perigon subtending each pistil) but gave the derivation of the second part of the compound as from "χητον", a word which, as explained by Nicolson & Mayo (l.c.), does not exist – certainly not in the intended meaning, and whose "eta" should anyway have been transliterated as "e" and not "ae". Given the clear intended original meaning, it should have been based on the masculine χιτων meaning "tunic", and transliterated as "chiton" (Nicolson & Mayo, l.c.). Schott (Aroideae: 10, t. 14. 1853; Gen. Aroid.: 68. 1858; Prodr. Syst. Aroid.: 344. 1860) corrected the spelling to Stylochiton but retained its neuter gender. Then, Engler (in Candolle & Candolle, Monogr. Phan. 2: 521. 1879) pointed out that both the spelling and gender of Leprieur's name were incorrect and used Stylochiton with masculine epithets. It remained widely used as Schott and then Engler had corrected it for well over a century until Nicolson & Mayo (l.c.) proposed masculine Stylochiton be formally conserved against "neuter" Stylochaeton, essentially to bind Engler's appropriate correction to both the spelling and gender. Apparently inexplicably, their proposal failed 6–5 against (Brummitt in Taxon 36: 736. 1987), with that report stating with peculiar diffidence that "[t]he name for this genus […] should apparently [sic] in future be given as Stylochaeton", but going on to communicate that the committee had nevertheless voted 6–5 in favour of it being treated as masculine even with the original spelling, though, with further diffidence, adding caveats that "[i]t is debatable […] whether this Committee has the authority to recommend a binding decision on this point [i.e., the gender], and secondly whether the required two-thirds majority (8 positive votes) should apply in this case or only in the conservation issue. [The provision to conserve a name with a particular gender appeared first in the Berlin Code (Greuter & al. in Regnum Veg. 131. 1994).] It is suggested [sic] that the 6–5 majority decision on the gender should be accepted." No reasoning was provided for the outcome and so it is not clear if that conservation proposal failed because some members of the Committee [for Spermatophyta] thought it was simply unnecessary (perhaps considering the case to be a straightforwardly correctable orthographic error), and/or whether and in what way some may have disagreed with its substance. At that time, the General Committee seemed only to deal with proposals recommended for acceptance by specialist committees (cf. Nicolson in Taxon 37: 440. 1988). Consequently, the matter has remained strictly unresolved. Nicolson & Mayo (l.c.) highlighted and itemised the almost entirely consistent use of masculine Stylochiton in taxonomic and floristic accounts from Engler onwards, but it is clear that instability has greatly increased after the Committee's response to their proposal. While floristic and taxonomic literature has largely but not exclusively (e.g., the generic monograph by Mayo & al., Gen. Araceae: 151. 1997, where Stylochaeton is treated as neuter) followed the diffident recommendations in Brummitt (l.c.) in using Stylochaeton with masculine epithets, other fields generally persist with Stylochiton. Searching Google Scholar on each spelling yields some 850 hits in a ratio of approximately 5:3 in favour of Stylochiton [approx. 4:3 when filtered post Brummitt (l.c.) and the same ratio when filtered for 21st Century only]. However, ING (https://naturalhistory2.si.edu/botany/ing/), IPNI (https://www.ipni.org/?q=stylochaeton), POWO (https://powo.science.kew.org) and the Naturalis Bioportal (https://bioportal.naturalis.nl/nl) (all accessed 7 Aug 2024), have adopted both the erroneous original spelling and neuter gender, thus following Brummitt (l.c.) on the orthography but not in the matter of gender. Other online databases and virtual herbaria (all accessed 7 Aug 2024), e.g., BM (https://data.nhm.ac.uk), GBIF (https://www.gbif.org/species/2871821), P (https://science.mnhn.fr/institution/mnhn/list?full_text=stylochaeton), and US (https://collections.nmnh.si.edu/search/botany/), treat Stylochaeton as masculine, while the gender is mixed at B (http://ww2.bgbm.org/herbarium/), BR (https://www.botanicalcollections.be/#/en/search/specimen) and JACQ (https://www.jacq.org/#database). Masculine Stylochiton is used at NY (https://sweetgum.nybg.org/science/vh/). Tropicos (https://www.tropicos.org/name/Search) and Global Plants (JSTOR; https://plants.jstor.org) have both spellings, mostly with masculine epithets. Two new species were described last year with neuter epithets in Stylochaeton (Struwig & al. in Phytotaxa 620: 1. 2023). Together, these instances highlight the ongoing want of a firm unambiguous determination or coalescence around a single consensual viewpoint. Based upon masculine Stylochiton being both etymologically correct and in somewhat wider modern use as well as much longer traditional use than Stylochaeton with either gender, we here propose again that masculine Stylochiton with that spelling be formally conserved. Guidelines for proposals such as this ask for counterargument. Given the extent of current instability in this instance, it could be said that any rational unambiguous determination on the orthography and gender of this generic name will be an improvement over the current shambles. One approach would be "originalist": to determine that Leprieur's neuter Stylochaeton should prevail simply because that is how it was established, regardless of its errors. The second available approach would be to enshrine as firm determinations the rather extensively ignored, unassertive suggestions in Brummitt (l.c.) of masculine Stylochaeton. The third, preferred, approach is to formally conserve the now one and a half centuries-old adoption of masculine Stylochiton as was proposed 40 years ago (Nicolson & Mayo, l.c.). Of these, the recommendation by the Committee for Spermatophyta in 1987 (Brummitt, l.c.) that the spelling be Stylochaeton and the gender be masculine was itself a linguistic error which has served only to compound rather than settle the issue. Nicolson & Mayo (l.c.) had pointed out that the ending, -ον [omicron nu], of the word Leprieur used as the basis for -chaeton, spurious though it was, signified neuter gender, and so that Committee's recommending the retention of the original spelling of the generic name while voting that it be treated as masculine was simply nonsensical from a linguistic point of view. The ending -ων [ōmega nu] from the corrected -chiton, however, is usually masculine and never correctly neuter (cf., for example, masculine Potamogeton). It can be said that, having been treated as masculine since 1879 (Engler, l.c.), masculine is the traditional gender to be retained (cf. Art. 62.1 of the Shenzhen Code, Turland & al. in Regnum Veg. 159. 2018). However, reverting to the original orthography effectively changes the derivation of the termination requiring a change in the gender – in this case reversion to neuter (cf. Art. 62.2). Choosing between the "originalist" option of etymologically and orthographically spurious neuter Stylochaeton and the long-ago corrected and long-used masculine Stylochiton appears straight-forward: Stylochiton has had far longer continuous majority use, and remains in majority use now. To formalise a reversion to Leprieur's neuter Stylochaeton would be the more disruptive course. The adoption of Stylochaeton by a number of taxonomists, but the ongoing use, regardless of the 40-year-old suggestions in Brummitt (l.c.), of Stylochiton by non-taxonomists, reflects the former's responsiveness and adaptability to recommended orthographic change, and therefore we can reasonably say that formally conserving Stylochiton will hardly traumatise the taxonomic community, but will provide welcome continuity for the non-taxonomic community whom we serve. In the event that this conservation proposal is deemed unnecessary, we request, given the context of decades of confusion and ambiguity imposed since the Committee's insufficiently decisive response to the previous proposal, an explicit determination that the name's orthography (and thence its gender) is to be corrected to masculine Stylochiton under Art. 60.1 of the Shenzhen Code, in order to finally bring stability to this matter.

A new species of Homalomena Chamaecladon Clade is described from the Bengoh Range, Kuching Division, Sarawak, and compared with the two most similar described species from Kuching: H. paucinervia from the Matang Massif, and H. santubongensis from Gunung Santubong. The three species are illustrated from living plants and differentiated in an identification key.

Homalomena atlas is described and illustrated as a new species from the western Rejang Basin and assigned to the Hanneae Complex of the Cyrtocladon Clade, taking the complex to 12 described species on Borneo.

Homalomena latisinus is described and illustrated as a new Bruneian species of the Homalomena Borneensis Complex from shaded damp kerangas. It is compared with the five species previously described for the complex.

Two new species of Burttianthus are described from Sarawak: B. rejangicus from the Rejang and Balleh rivers of the western Rejang Basin, and B. solus from the Similajau Basin, Bintulu. Both novelties are illustrated from living plants and the spadices of eight of the nine Burttianthus species are compared in accompanying figures.

Two ornamental new species of Schismatoglottis are described and illustrated from Borneo. Schismatoglottis metallica from Kalimantan Barat, Indonesian Borneo, assigned to the Schismatoglottis Multinerva clade, and S. reticosa from the upper Engkari river in SW Sarawak, Malaysian Borneo, provisionally placed in the Petradoxa clade. Recognition of these novelties takes Schismatoglottis on Borneo to 132 species, of which 86 have been described since the year 2000.

Schottarum inconspicuum S.Y.Wong & P.C.Boyce, is described as a new species from the easten part of the Rejang Basin, taking the genus to three species. All are illustrated from living plants. A distribution map is provided.

Schismatoglottis auyongii is described and illustrated as a new clumping species of the Schismatoglottis Calyptrata clade from wet slopes in hill forest on the extremely hard Paleogene sandstones of the Penrissen Range, SW Sarawak.

Bucephalandra adei S.Y.Wong, P.C.Boyce & A.Y.M.Hii, is described as new additional the six already known species in which the spadix appendix exceeds the length of the fertile portion of the spadix. All are endemic to Borneo. An key to identification for the seven species and a distribution map is provided. Recognition of B. adei takes Bucephalandra to 32 described species.

Homalomena joanneae is described and illustrated as a new species of the Chamaecladon Clade restricted to the industrially threatened limestone of Gunung Kanthan, Kuala Kangsar, Perak, and compared with its probable nearest congener, H. hendersonii from Kelantan.

Araceae is recognized as keladi hutan or ubi keladi to the local community in Malaysia. The aim of this study is to provide an update checklist and description on ecology of Araceae in Lojing Highlands, Gua Musang, Kelantan, Peninsular Malaysia. The survey was applied the random sampling technique. The result shows that a total of 25 species from 15 genera of Araceae were revealed from the area. This figure constitutes about 17.9% out of 140 species and 53.6% of the 28 genera of Araceae documented in Peninsular Malaysia. Most of them, 23 species or 92.0% are common in tropical rainforest. However, two species which considered as rare, these are Alocasia inornata Hallier f and Arisaema anomalum Hemsl.

Two new Hanguana species from Kalimantan, Indonesian Borneo, are described here. Hanguana karimatae from Karimata Island, West Kalimantan province, is characterised by a stout habit, prominently oblique yellow fruits with raised stigma and 1- or 2-seeded fruits. Hanguana nana from Central Kalimantan province is the smallest species in the genus with the stem entirely covered by leaves, deflexed barely branched infructescences with only a few fruits, each with a single bowl-shaped seed with a large and incurved appendage. These are the first descriptions of new Hanguana species from Kalimantan (Indonesian Borneo). Colour plates as well as notes on distribution, ecology, habitat and conservation status are provided.

Three new colonial species of Schismatoglottis Calyptrata clade are described and illustrated from Sarawak and compared with the four pre-existing morphologically similar species occurring in the state. A modified description of Schismatoglottis niahensis is provided to correct a previous misinterpretation of the stem architecture. All seven recognized species are illustrated from living plants.

Homalomena puncticulosa is described and illustrated as a new species of the Chamaecladon Clade known from a single population in Selangor, and compared with the superficially similar H. kiahii Furtado, and other similar Sumateran species.

A new species of Homalomena Chamaecladon Clade is described from the Santubong Peninsula, Kuching Division, Sarawak, to where it is endemic, and compared with H. paucinervia from the nearby Matang Massif, and with H. atrox from Sri Aman, the two other most similar described species from NW Borneo. All three species are illustrated from living plants, and keyed-out.

Homalomena acuminata (Ridl.) S.Y. Wong & P.C. Boyce and H. ridleyi S.Y. Wong & P.C. Boyce are described and illustrated as new species of the Griffithii complex of the Chamaecladon clade restricted respectively to sandstones and forested karst formations in NW Borneo, Malaysia. A key to the described species of the Griffithii complex on Borneo is provided.