Campylosiphon saundersii X.J.Li, L.Qu & D.X.Zhang, 2023

Li, Xiaojuan, Qu, Lu, Hu, Guoxiong & Zhang, Dianxiang, 2023, Revision of Campylosiphon (Burmanniaceae), with New Combinations and a New Species Described, Systematic Botany (Basel, Switzerland) 48 (3), pp. 395-409 : 403-406

2. Campylosiphon saundersii X.J.Li, L.Qu & D.X.Zhang , sp. nov. TYPE: CHINA. Guizhou: Suiyang, Zunyi , 877 m a.s.l., July 2019, L. Qu 0852201907200001 (holotype: IBSC!; isotypes: IBSC!, KIB!, SWFC!)

Fully mycoheterotrophic herbs; whole plant whitish; rhizomes tuberous, cylindrical, apical part densely covered with stiff scale-like leaves; stems unbranched, erect, 5–12 cm in high at flowering; leaves sparsely beset on stem, scale-like, appressed, ovoid or oblong, apex acute, 4–6 mm long, 1 mm wide; bracts like stem leaves, lanceolate or ovoid, acute, 2–5 mm long, about 1.5 mm wide; inflorescence terminal, about 8 flowers in bifurcate cincinnus; flowers about 10 mm long, 2 mm wide, prominently pedicellate, ca. 4–10 mm long; six ribs from the apex of lobe to the base of ovary; perianth tube triangular-cylindric, about 4 mm long; perianth pure white with two whorls of white lobes (3 1 3); outer lobes ovoid to oblong, 1.5–3 mm long, about 1–2 mm wide at base, margins involute, from middle-upper to apex, apex caudate; inner lobes oblong, about 0.8 mm long, 0.3 mm wide, apex obtuse or rounded; stamens three, below the inner lobes, with short filaments connective, base mucronate, lacking basal spur; style filiform, with three style-braches stigmas at top, stigma infundibular; ovary subglobose or elliptical, about 2 mm long, 1.5 mm wide; seeds yellow, numerous, laterally flattened, sub-globose, triangular or elliptical. Figures 1 , 2 , 3E , 4B .

Etymology —This species is named after Prof. Richard M. K. Saunders, in recognition of his contribution towards the study of the mycoheterotrophic plants.

Phenology —Flowering and fruiting from July to August.

Distribution and Habitat — Campylosiphon saundersii is hitherto only found in one population in a bamboo forest near the Kuankuoshui National Nature Reserve, Zunyi city, northern Guizhou province, China. The species grows on rich humus soils or wet rock surfaces in bamboo forests.

Preliminary Conservation Status —Only one population of C. saundersii with ca. 20 individuals was found at present. The lack of extensive study hinders the accurate conservation

status evaluation of this species. Thus, we here temporarily propose that C. saundersii be considered Data Deficient (DD) according to the IUCN Red List Categories ( IUCN 2012), although the IUCN recommends that care be taken to avoid classifying species as “data deficient” when the absence of records may indicate dangerously low abundance.

Notes — Campylosiphon saundersii resembles both Campylosiphon purpurascens and Burmannia unguiculata Aver. in having slightly curved perianth tube and the outer whorl of perianth lobes with long acute and caudate tip at the apex. Campylosiphon saundersii differs from B. unguiculata by having more flowers in one inflorescence, whitish plant, leaves sparsely arranged on the stem, and stamen connective with inconspicuous median point, while B. unguiculata is a white blue herb having inflorescence with only two to four flowers, numerous leaves densely arranged on the stem, and three-lobed stamen connective with distinctly median point appendage. Thus B. unguiculata might belong to Campylosiphon , but this proposal remains to be verified by further phylogenetic inference based on DNA datasets, which we were not able to conduct in this study.

3. CAMPYLOSIPHON CONGESTUS (C.H.Wright) Merckx ex Maas (2010 , in: Flore du Gabon, vol. 41, p. 67). Gymnosiphon congestus C.H.Wright (1897, in: Thiselt.-Dyer, Fl. Trop. Afr. 7, p. 12). Burmannia congesta (C.H.Wright) Jonker (1938 , in: Meded. Bot. Mus. Herb. Rijks., Univ. Utrecht 5l, p. 94). TYPE: NIGERIA. Rivers State: Nun River, 1860, Mann 515 (lectotype: K barcode K000366035!, designated by Jonker in: Meded. Bot. Mus. Herb. Rijks., Univ. Utrecht 5l, 1938, p. 95).

Burmannia aptera Schltr. (1906, in: Bot. Jahrb. Syst. 38, p. 141). TYPE: CAMEROON. South-West Region: Moliwe, precise locality unknown, R. Schlechter 15787 (lectotype: B barcode B100165442!; isolectotypes: BR barcode BR000000864314! and P barcode P00753796!, designated by Dianxiang Zhang in Ph. D. thesis, Univ. of Hong Kong , 1999, p. 282).

Fully mycoheterotrophic perennial herbs, whole plant white or blue. Stems thick filiform, succulent; roots robustly fibrous; rhizomes tuberous; rhizome and base of stem densely covered with scale-like leaves; leaves sparsely beset on the stem, brownish, stem leaves ovate-triangular, acute, appressed, 2–5 mm long; inflorescence capitate, a double cincinnus or cyme-like with 4–20 flowers; bracts similar to stem scales; flowers 6–11 mm long, sessile or with extremely short pedicel ca. 0.5 mm long; perianth white, wingless; perianth tube cylindrical, 3–6 mm long; outer perianth lobes broad ovate-triangular, thin, acute, with involute margins, 1.2–2.6 mm long; inner lobes spathulate, apex rounded, thin, revolute, 0.8–1.4 mm long; stamens sessile or with short, thick filaments, inserted on the perianth throat; connective with two short arms bearing the thecae, a median point directed inward, apical crests and basal pendant spur lacking; style filiform, three subsessile stigmas at the apex, style and stigmas together as long as the perianth tube; ovary ellipsoid to sub-globose, 2–4 mm long; capsule sub-globose, dehiscing by non-transverse slits; seeds sub-globose, numerous.

Phenology —Flowering and fruiting year round.

Distribution and Habitat —Mainly distributed in Western Africa, and usually grows in moist places on forest floor.

Notes —Merckx (2008) treated Burmannia densiflora as the synonym of C. congestus species, combined the morphological

analysis and phylogenetic inference, and indicated that both B. congesta and B. densiflora are indigenous to West Africa and differ from the other Burmannia species by the absence of wings on their flower tubes and the presence of tuberous rhizomes. This treatment was performed by Maas and Maas-Van de Kamer (2010). However, after morphological comparison among Burmannia and Campylosiphon , we disagree with the transfer made by Merckx (2008) and Maas and Maas-Van de Kamer (2010) as B. congesta is distinct from B. densiflora in having capitate or cyme-like inflorescence with less than 20 sessile or subsessile flowers having distinct longer perianth tube, while B. densiflora has cincinnus inflorescence with up to 30 flowers having obvious pedicel almost equal to perianth in length. Phylogenetic relationships of Campylosiphon species including more samplings inferred from mitochondrial DNA sequence nad1 b-c also well supported that B. densiflora is distinct from B. congesta ( Fig. 9 ). We thus regard B. densiflora as a distinct species and transfer this species to Campylosiphon as C. densiflorus .

The protologue of Gymnosiphon congestus cited two collections with collection numbers Bates 370 ( Fig. 4C ; Supplemental Fig. S2C ) and Mann 515 ( Fig. 4D ; Supplemental Fig. S2B ), collected from Cameroon and Nigeria, respectively, in the protologue of Gymnosiphon congestus . Four decades later, Jonker (1938) selected Mann 515 as the holotype of Burmannia congesta and treated Burmannia aptera as a synonym of B. congesta , whereas Bates 370 was identified as a specimen of Burmannia densiflora . In this study, we recognized that the individuals from these two collections, Mann 515 and Bates 370, are obviously different. For example, individuals from “ Mann 515 ” are more similar to the holotype of B. aptera , while the individuals from “ Bates 370 ” are more similar to those from the collections (collection number: Wamtin, Le Testu 5936 with herbarium barcodes: BR00000873573 and P02144506) from Gabon identified as Burmannia congesta var. congesta by Zhang (1999) which share some morphological characters with both Campylosiphon congestus and Burmannia densiflora . Such as, the individuals from “ Bates 370” and “ Wamtin, Le Testu 5936,” are very similar to B. densiflora in having double cincinnus inflorescence with many flowers, and resemble C. congestus in having sessile flowers, longer perianth tube. and sub-globose capsule. Until a detailed study of C. congestus s.l. involving various populations across Africa is carried out, a broad concept of C. congestus is accepted at present.

Additional Specimens Examined — Cameroon. — EFULEN, BULE COUNTY: G. L. Bates 370 (E00044117). — NYABESSAN: 20KM to SSE from Zingui, R Letouzey 9050 (P01757271 and P01757272). — SOUTH REGION: S. bank of Lobe river , JJ Bos 4818 (P01757270 and WAG.1489097) ; ca 6 km N of Kribi , MEE Hijman, JCA Weerdenburg 311 (U.1173847) ; Station du Cacaoyer de N’ koemvone, JJFE de Wilde 8351 (WAG.1489098). — SOUTH-WEST REGION: Korup National Park , XM van der Burgt, S Njibili, C Okha & M Elangwe 1122 (WAG.1489017) . Gabon. — HAUTE- NGOUNYe: Wamtin, M Le Testu 5936 (BR00000873573 and P02144506). — NGOUNIe: JJFE de Wilde & MSM Sosef 10441 (WAG.1489108). — WOLEU-NTEM: JJ Wieringa 670 (WAG.1489107). — ESTUAIRE: Olivier Lanchenaud, Eddy Ngagnia, Gretchen Walters & PC Koumba Ipa 1207 (BR0000015222916V) . Nigeria. — CALABAR: Orem district , MG Latilo, JR Charter & BO Daramola 45818 (FHI0045818–0) . Liberia. — LOFA, GOLA FOREST: CCH Jongkind, AK Daniels, J Konie & MG Gorpudolo 7012 (WAG.1489101). — MIMBA: JG Adam 26570 (P01757273!). — SINO: Sapo National Park , buffer zone, CCH Jongkind et al. 5463 (WAG.1489100) ; inside Sapo National Park , CCH Jongkind, D Bilivogui & AK Daniels 9759 (WAG.1489099) .

Figures

FIG. 1. Habitat and morphology of Campylosiphon saundersii. A. Habitat. B. entire flowering plant. C. Tuberous rhizome. D. Inflorescence. E. Seeds. F. Perianth viewed from inside. G. Styles and stigmas. H. Stigma. Scale bars: 3 cm (B); 1 cm (C); 2 mm (D); 300 Mm (E, F); 200 Mm (G, H). A–D were photographed by Lu Qu, E–H were photographed by Xiaojuan Li.

FIG. 2. Line drawing of Campylosiphon saundersii. A. Entire flowering plant. B. Flower. C. Perianth viewed from inside. D. Vertical view of perianth. E. Schematic diagram of ovary, transverse section in the middle part. Scale bars: 3 cm (A); 4 mm (B); 4 mm (C); 4 mm (D); 2 mm (E). Drawn by Ms. Yunxiao Liu.

FIG. 3. Five species of Campylosiphon. A. Campylosiphon congestus, photographed by Dr. Merckx. B. Campylosiphon densiflorus, part of holotype (Barcode: B100165441). C. Campylosiphon purpurascens, photographed by Dr. Merckx. D. Campylosiphon championii, photographed by Xiaojuan Li. E. Campylosiphon saundersii, photographed by Lu Qu.

FIG. 4. Continuous variation of floral morphology among Campylosiphon lineages. A. Campylosiphon purpurascens, partial of holotype (Barcode: B100165441). B. Campylosiphon saundersii, photographed by Qu Lu. C. Campylosiphon congestus, partial of specimen sheet (Barcode: E00044117). D. Campylosiphon congestus, partial of holotype (Barcode: K000366035). E. Campylosiphon sp., partial of herbarium specimen collected from the Western Ghat, India (Barcode: MH00018421). F. Campylosiphon championii, partial of holotype of Burmannia chionantha (Barcode: B100296387). G. Campylosiphon sp., partial of herbarium specimen collected from Java (Barcode: L.1486663). H. Campylosiphon congestus, partial of holotype of Burmannia aptera (Barcode: B100165442). I. Campylosiphon championii, partial of holotype of Burmannia dalzielii (Barcode: BM000058511). J. Campylosiphon densiflorus, part of holotype (Barcode: B100165441). K. Campylosiphon championii, partial of Burmannia tuberosa lectotype (Barcode: FI013466). L. Burmannia micropetala, partial of holotype (Barcode: BM000058513).

FIG. 9. Phylogenetic relationships of Campylosiphon species based on mitochondrial sequence nad1 b-c. Name of taxon in red indicates this taxon is fully mycoheterotrophic.