Thismia latiffiana differs from all its congeners by the following combination of traits: the presence of golden trichomes on the outer surface of floral tube and mitre, outer tepals absent, inner tepals form a mitre without appendages, an inner surface of floral tube covered by pyramidal protuberances and supraconnective bilobed with each lobe terminated by a long, needle-like trichome.

Figure 1. 

Illustration of Thismia latiffiana A habit, showing roots, young bud (Ai; note stems covered with trichomes), mature flower (Aii) and fruit (Aiii; note glabrescent stem with trichomes detached) B Leaf (adaxial) C bract (adaxial), smaller bract (Ci) D longitudinally dissected floral tube showing inner (abaxial) view of stamens and apical parts of connectives E portion of inner surface of floral tube (upper part) F trichomes on outer surface of floral tube; G outer (adaxial) view of stamens showing lateral appendages H stamen, view from below I gynoecium, longitudinal section, showing pistil with trilobed stigma and ovary J seed. All from FRI94686 (spirit material). Drawings by Mohamad Aidil Noordin.

Malaysia. Peninsular Malaysia: Terengganu: Setiu District, Hulu Nerus Forest Reserve, approximately 220 m elev., 4 February 2020, Siti-Munirah & Dome Nikong FRI94686 (holotype KEP!, spirit collection, barcode no. 280004).

Figure 2. 

Thismia latiffiana, external morphology A roots B mature flower C apical part of floral tube with opening aperture D apex of mitre E ovary, side view F mature flower G trichomes resembling spines on an areole of cacti H mitre, side view. All from FRI91117: A, B, C, D FRI94686: E, F, G, H. Photos by Dome Nikong (A–D) and Siti-Munirah MY (E–H). Images not to scale (see dimensions in description and Figure 1).

Herb achlorophyllous, approximately 12 mm tall. Roots loosely coralliform, compressed, light brown, surface covered with trichomes. Stem very short or absent, obscured by trichomes during flowering. Leaves spirally arranged, crowded, scale-like, triangular, apex acute to acuminate, margin entire, 2–8 mm long and 1.5–2 mm wide, brown. Bract similar to leaves. Flowers actinomorphic, solitary; floral tube 1.2 cm long, ellipsoid to ovoid, widest in middle part (7–7.3 mm in diameter), in upper part ca. 6.4 mm wide and at base ca. 6 mm wide, black or dark brown, whitish in upper part with round to oblong sectors (opposite each anther thecae), separated by blackish-brown stripes; surface partially covered with individual unbranched trichomes, stellate trichomes or unbranched trichomes crowded on warts (resembling spines on areoles of cacti); inner surface covered with very thick pyramidal protuberances arranged longitudinally in each section continuously, brown to black at middle towards base, upper part reticulate, light brown. Annulus at apical part of floral tube, dark brown, broadly funnel-shaped, ca. 2.7 mm wide, margin 6-lobed, glabrous, smooth, and thick. Outer tepals absent. Inner tepals 3, dark brown to blackish, erect and turning inwards, connate at the top forming a mitre without any appendages; mitre black or dark brown, on outer surface partially covered in a patchy manner with individual unbranched trichomes, stellate trichomes or unbranched trichomes crowded on warts (resembling spines on areoles of cacti); glabrous, smooth, blackish-brown on inner surface; mitre openings 3, ca. 3.5 mm × 5.2 mm. Stamens 6, pendent from the apical margin of the floral tube, dark brown; filaments free, short; connectives broad, flattened, laterally fused together and skirt-like, trigonous, ca. 2.4–2.7 mm × 1–1.4 mm, somewhat raised below thecae, flat on the side pointing to the centre of flower (towards apex); supraconnective apex 2-lobed, each lobe with solitary transparent needle-like trichomes ca. 0.5–0.6 mm long; thecae yellowish, surrounded by tufts of hairs at middle part; lateral appendage protruding towards floral tube, quadrangular, equalling the apex of supraconnective, with a horn-like projection arising from each side, margin shallowly dentate and sparsely hairy; interstaminal glands inserted on the lines of fusion between connectives. Ovary inferior, bowl-shaped, whitish-brown, warty, enveloped by bracts and leaves. Style ca. 0.8–0.9 mm long × 0.5–0.8 mm wide; stigma deeply trilobed; lobes curved inwards, ca. 2.2 mm long, surface papillose, dark brown. Fruit a cup- or bowl-shaped or pyxidium capsule, 2.6 mm in diameter, dark brown to blackish-brown, borne on an elongated pedicel up to 7–10 cm long, distally covered with old dusty trichomes, proximally glabrous.

Figure 3. 

Thismia latiffiana: inner floral structure A, B floral tube, longitudinal section B shows pistil and inner surface of floral tube covered with pyramidal protuberances arranged longitudinally C floral tube, upper portion of longitudinal section D inner (abaxial) view of stamens showing supraconnectives E outer (adaxial) view of stamens showing lateral appendages F pistil, top view, showing stigma G pistil, side view H fruit, top view. All from FRI91117: A, B, F FRI94686: C, D, E, G, H. Photos by Dome Nikong (A, B, F) and Siti-Munirah MY (C, D, E, G, H). Images not to scale (see dimensions in description and Figure 1).

Peninsular Malaysia. Terengganu: Setiu, Hulu Nerus Forest Reserve, ca. 220 m elev., 26 December 2019, Dome Nikong FRI91117 (KEP, spirit collection, No. barcode 280003).

Endemic to Peninsular Malaysia, Terengganu. Currently known only from the type locality.

In a lowland dipterocarp forest, on moist soil, under shade, near an open place (walking trail) (Figure 4) at elevation of 220 m. Flowering from December to February.

Figure 4. 

Thismia latiffiana Siti-Munirah & Dome A walking trail near the habitat B plant in its habitat C plant ex-situ. Photos by Siti-Munirah MY (A, C) and Dome Nikong (B).

Thismia latiffiana is named in honour of Emeritus Professor Dato’ Dr. Abdul Latiff Mohamad, a prominent botanist and conservationist in Malaysia.

We suggest a local name as ‘Thismia burung hantu’ in Malay, due to its appearance resembling an owl (‘burung hantu’ = owl).

Critically Endangered (CR B2ab(ii,iii)). Following the IUCN Red List Categories and Criteria (IUCN 2019), this species is assessed as Critically Endangered because it is currently known only from a single locality, where only two individuals were observed. The locality is within the Forest Reserve, but it is exposed to tourism activities within the Lata Payung Recreational Forest and Gunung Sarut. The habitat of the species is near the main trail from the entrance of Lata Payung to the ‘blue pool’ towards Gunung Sarut. Efforts to trace this species in the surrounding area were unsuccessful. Considering its small population and the threats to its microhabitat, T. latiffiana is assessed as Critically Endangered.

As follows from its morphology, T. latiffiana belongs to the section Sarcosiphon (Blume) Jonker (Jonker 1938). In addition, following the identification key in Kumar et al. (2017), T. latiffiana is falling within the subgen. Thismia sect. Sarcosiphon due to the arrangement of inner tepals into a mitre, the absence of outer tepals and a mitre lacking a filiform appendage. Additionally, based on the phylogeny in Shepeleva et al. (2020), T. latiffiana should belong to or near to clade 3 for its coralliform roots, inner tepals fused into a mitre, absence of mitre foveae and absence of outer tepals.

In the section Sarcosiphon, the gross morphology of T. latiffiana is similar to that of several other species, such as T. brunneomitroides Suetsugu & Tsukaya (Suetsugu et al. 2017), T. brunneomitra Hroneš, Kobrlová & Dančák (Hroneš et al. 2015), T. crocea (Becc.) J.J.Sm. (Beccari 1878) and T. cladestina (Blume) Miq. (Chantanaorrapint et al. 2015). These species share with T. latiffiana a brown flower colour and an erect mitre with three lateral holes. However, all these abovementioned species have a long stem during flowering and densely clustered coralliform roots and T. latiffiana differs from them in having a very short (almost lacking) stem during flowering and rather loose coralliform roots. The new species is unique amongst the known Sarcosiphon species in having several unparalleled traits. Thismia latiffiana is recognisably different from all its congeners by the presence of golden trichomes on the outer surface of the floral tube, the pyramidal protuberances on the inner side of the floral tube and the supraconnective terminating into two long trichomes.

In Peninsular Malaysia, the most similar species is T. sitimeriamiae as it also has a very short stem during flowering and the presence of simple or occasionally apically stellate trichome structure on the outer side of the floral tube. However, it has minute, but distinctly developed, outer tepals and inner tepals forming a flattish, umbrella-like mitre. Therefore, the overall morphology of both species is completely different. For the record, T. latiffiana have been discovered in the same Forest Reserve as T. sitimeriamiae. Further investigation should be carried to better understand their relationship.

Interestingly, another species of sect. Sarcosiphon has been reported from Peninsular Malaysia (Perak, Gunung Hijau) by Ridley who described it as Bagnisia crocea var. brunnea Ridl. (Ridley 1907). Jonker (1938, 1948) pointed out that it is highly unlikely that the specimen from Perak can be attributed to T. crocea from New Guinea although he did not see any specimen. A possible holotype of Bagnisia crocea var. brunnea (Ridley s.n., SING 0052732!) contains an illustration and single dried plant that has coralliform roots and almost lacks stem during flowering and it is, in general appearance, similar to T. latiffiana. Therefore, it is possible that both taxa are conspecific. However, the illustration differs from T. latiffiana by small processes on the top of the mitre. Additional fieldwork and research is needed to resolve whether these two taxa are conspecific or not.