Lethocolea pansa (Taylor) G. A. M. Scott & K. G. Beckm.

Gradstein, S. Robbert, Ilkiu-Borges, Anna Luiza, Cargill, D. Christine, Beckmann, Karen & Vanderpoorten, Alain, 2024, An integrative taxonomic study of the genus Lethocolea (Marchantiophyta: Acrobolbaceae), Plant Ecology and Evolution 157 (3), pp. 375-398 : 375-398

1. Lethocolea pansa (Taylor) G. A. M. Scott & K. G. Beckm. ( Scott and Beckmann 1987: 212)

Figs 1 , 3 , 4 , 5 , 6

Jungermannia pansa Taylor ( Taylor 1846: 275) – Type: same as for Lethocolea pansa.

Podanthe squamata Taylor ( Taylor 1846: 413) – Type: Australia – West Australia • Swan River; 1843; Drummond s. n.; lectotype (designated by G. A. M. Scott, in Zijlstra 1990): BM [ BM 000969499]; isolectotypes: BM [ BM 000969500], BM [ BM 000969524], FH [ FH 01122547].

Calypogeia squamata (Taylor) Spruce ( Spruce 1882: 94) – Type: same as for Podanthe squamata.

Lethocolea squamata (Taylor) E. A. Hodgs. ( Hodgson 1958: 582) – Type: same as for Podanthe squamata.

Gymnanthe drummondii Mitt. ( Mitten 1854: 144), nom. illeg. – Type: NEW ZEALAND – North Island • “ forests of Titiokura ” (fide Mitten 1854); c. marsup.; Colenso 3649; lectotype (designated here): NY [ NY 04461792]. The other syntype (Colenso 3681, NY) is L. javanica.

Lethocolea drummondii Mitt. ( Mitten 1877: 190), nom. illeg. – Type: same as for Gymnanthe drummondii.

Podanthe drummondii Gottsche ( Gottsche 1880: 54) – Type: same as for Gymnanthe drummondii.

Symphyomitra drummondii (Gottsche) Steph. ( Stephani 1901: 1123) – Type: same as for Gymnanthe drummondii.

Type.

Australia – West Australia • Swan River ; on clay; s. d.; Drummond s. n.; lectotype (designated here): FH [ FH 01122546 ]; isolectotype: BM [ BM 013763002 ] .

Description.

Plants dioicous, 1–2 cm long, 1–3 mm wide, creeping, flaccid, glossy green to purplish when fresh, usually brownish in herbarium, with or without a short ventral stolon near the base, lateral branches scarce, innovations not observed. Stems ca 0.2–0.4 mm in diameter, rather fleshy and fragile, made up of large, thin-walled cells, upper surface green to brownish-green, ventral surface usually dark purplish-reddish. Rhizoids scattered, hyaline. Leaves present throughout the stem, succubous, imbricate, obliquely to widely spreading, somewhat asymmetrically ovate to ovate-oblong, 0.9–1.6 × 0.6–1.2 mm, ca 1.5 × longer than wide, flat or slightly concave, usually unpigmented, occasionally with some brownish-purple pigmentation in older portions of the stem, apex broadly rounded, dorsal and ventral bases not decurrent. Leaf cells thin-walled, without or with very small trigones, less than 3 µm in diameter, sides of trigones concave (not bulging outwards), subrectangular, in the ventral and basal part of the leaf much larger than in the dorsal and apical part, dorsal cells 30–50 × 20–35 µm, ventral cells 40–100 × 30–50 µm, towards the leaf base over 100 µm long; margin cells slightly smaller, subquadrate, ca 25–30 µm; cuticle smooth; oil bodies (degenerated in herbarium material) always one per cell, ca 10–20 µm long, greyish-brown. Androecia terminal, bracts in 3–4 pairs, base saccate; antheridia one per bract, ovoid, with a short, biseriate stalk. Gynoecia bracts in 3–5 pairs, slightly larger than vegetative leaves (except for the smaller inner bracts at the mouth of the marsupium), spreading outwards, flat, dorsal margin somewhat undulate. Marsupia linear, green to greenish-brown, with almost smooth surface, up to 10 mm long, ca 0.5 mm in diameter, marsupial canal lined by numerous large, elongate, papilliform cells. Sporophytes not observed. Gemmae positioned on the dorsal stem surface or in leaf axils near the stem apex, dull green to light brown, orbicular to slightly longer than wide, 0.2–0.4 mm in largest diameter, 8–20 cells across, biconvex, 5–7 cells thick in the middle, 1–2 cells thick at the margin, cells subisodiametric, ca 25 µm in diameter, margin cells not or partially transparent only, not forming a distinct wing, outer wall convex but usually not protruding outwards (exceptionally one or two cells protruding outwards), margin of gemmae crenulate. Gemmalings common, much more slender than ordinary plants, originating from the centre of the gemmae and consisting a long, almost colourless, almost bare microphyllous shoot terminating in a few densely imbricate leaf pairs.

Distribution.

Australia, New Zealand, South Africa. The distribution of Lethocolea pansa in Australia and New Zealand needs further study as part of the published records from these countries (e. g. Engel and Glenny 2019; Schuster 2021), viz. plants with a papillose cuticle, distinct trigones, and winged gemmae, belong to L. javanica (see below). As shown here, published records of L. pansa from New Caledonia ( Stephani 1922 as Gongylanthus leratae ; Hürlimann 1974, 1985) belong to L. javanica as well.

Habitat.

On bare, moist soil along trails, on road cuts and in open, mesic woodlands and scrub, also on soil over sandstone rock and near water, ca 150–1000 m. Scott (1985) noted that Lethocolea pansa may have the widest ecological tolerance of any Australian liverwort, “ growing in dry and hot at one extreme, but found as a floating aquatic at the other extreme, and all stages between ”, but Scott and Beckmann (1987) found that records from very dry habitats belonged to Gongylanthus scariosus (Lehm.) Steph. Moreover , the present study shows that part of the published records of L. pansa from Australasia refer to L. javanica .

Additional material examined.

Australia – New South Wales • Kyeamba Travelling Stock Reserve South of Tarcutta ; 356 m; c. gemm.; Purdie 8216 A; CANB [ CANB 800536 ] • Weddin State Forst, 17 km SW of Grenfell ; Curnow 1850; CANB [ CANB 8900876 ] • Lachlan Range State Forest, 15 km NW of Rankins Springs ; c. gemm.; Curnow 3367; CANB [ CANB 9404944 ] • Goonoo State Forest, 5 km E of Mogriguy Forest Road , ca 23 km direct NNE of Dubbo ; c. gemm.; Curnow 6567; CANB [ CANB 672034 ] • Goonoo State Forest, 3 Corners road , 1.5 km W of Dubbo – Mendooran road ; c. gemm.; Curnow 6597 A; CANB [ CANB 672077 ] . – Northern Territory • NE Arnhem Land, Gore, Rindarry Creek ; Russell-Smith 4829; CBG [ CBG 8803914 ] . – Queensland • Silver Valley Road, 4.4 km by road SW of Herberton ; c. gemm.; Curnow 6871; CANB [ CANB 898903 ] . – South Australia • Kangaroo Is., Western River Conservation Park, Waterfall Creek , 30 km ENE of Cape Borda ; Streimann 54953; CBG [ CBG 9511339 ] . – Western Australia • Serpentine National Park, 2.5 km S of Jarrahdale ; 150–200 m; Pócs 04143 / M; EGR • Darling district, Perup Ecological Reserve ; Cargill 665; CANB [ CANB 7590021 ] • Bullfinch Evanston Road, 69.3 km (by road) N of Bullfinch ; Curnow WA 118; CANB [ CANB 879890 ] • Karolin Rock, 20 km (by road) NW of Bullfinch ; Curnow WA 130; CANB [ 879902 ] • North Boundary Road, ca 3 km N of Kingston Road , ca 5 km E of Yornup ; Cargill 1200 WA; CANB [ CANB 900850 ] • ‘ Grevillea Rock’, ca 25 km by road SE of Bridgetown , ca 1 km N towards Winnejup ; Cargill 685 GR; CANB [ CANB 759031 ] .

South Africa – Western Cape Province • Kasteel Poort ; Arnell 1031; BOL • Kasteel Poort ; Arnell 1036; paratype of Symphyomitra tabularis ; G • Constantia slopes ; Arnell 323; BOL, JE (2 colls.) • Constantia slopes ; Arnell 387; BOL • Constantia Nek ; Arnell 316; BOL • Track from Constantia Nek to Table Mountain ; 630 m; Arts 129 / 11; BR [ BR 5040313689887 ] • De Hoek, North foot of Zitzikanna Mts near Joubertina ; ca 550 m; c. gyn.; Esterhuysen 27343; BOL • Riviersonderend Mts, Boesman’s Kloof, path below De Galg ; ca 1000 m; Hedderson 15268 b; BOL • Swellendam-Ashton area, W slopes of Langeberg, Sitruspoort farm ; ca 600 m; c. gyn.; Hedderson 15301; BOL .

Notes.

Lethocolea pansa is characterized by the glossy green to brown (occasionally purplish) plants with dark purplish-reddish ventral stem surfaces, hyaline rhizoids, very thin-walled leaf cells without or with very small trigones, smooth cuticles, a single greyish-brown oil body per cell, up to 10 mm long marsupia, and dull green to brownish gemmae, 8–20 cells across, with a crenulate margin and no wing. Lethocolea pansa has been confused with L. javanica , which had been included as a synonym in L. pansa by recent authors following Grolle (1965, as L. squamata ). Lethocolea javanica differs from L. pansa in the dull green (shaded sites) to carmine-red (exposed sites) plant colour, leaf cells with distinct trigones and a densely papillose cuticle (to be studied carefully: in older herbarium material the papillae may be somewhat inconspicuous), and smaller, pale-green gemmae with a strongly crenate margin and 1–2 cell wide transparent wing (Figs 3 – 5 ). Scott and Beckmann (1987), moreover, found that gemmalings of L. pansa germinated from the centre of the gemmae, supporting the earlier findings of Goebel (1906) from plants he had identified as L. drummondii . In contrast, gemmae of L. javanica (identified as L. squamata ) germinated from the margins. Due to the densely papillose cuticle and the well-developed trigones, L. javanica is a more dull-coloured plant than L. pansa , and more rigid. The detailed description and illustration of L. pansa in Engel and Glenny (2019) is a combination of L. javanica and L. pansa .

The leaves in Lethocolea pansa are ovate to ovate-oblong (1.0–1.7: 1), but in one collection from Serpentine National Park, Western Australia (Pócs 04143 / M), they are ovate-orbicular to narrowly lingulate, becoming increasingly elongate towards the base of the shoots. As a result, the outline of these plants is more or less triangular.

Lethocolea pansa resembles L. naruto-toganensis from Japan in the smooth cuticle and the wingless gemmae; the latter species differs from L. pansa in having purplish rhizoids, green stem undersides, colourless oil bodies, and paroicous sex distribution. Moreover, the gemmalings of L. naruto-toganensis originate from the margins of the gemmae ( Furuki 2001), while those of L. pansa originate from the centre.

Lethocolea pansa is newly recorded here from South Africa, where it was previously labelled as L. congesta or Symphyomitra tabularis ( Arnell 1953) . The latter species was described based on a mixture of L. congesta and L. pansa , and was placed in the synonymy of L. congesta by Arnell (1955, 1963). Lethocolea congesta clearly differs from L. pansa in the rather dull-coloured, green to yellowish-green to yellowish-brown plants with unpigmented stems (but leaves may occasionally be tinged purple), leaf cells with trigones, a densely papillose cuticle, and 1–3 dark brown oil bodies per cell (usually 2) (Figs 1 , 3 ) The marsupia of L. congesta are significantly shorter than those of L. pansa , up to maximally 3 mm, and the marsupial canal is lined by few large, papilliform cells. Gemmae are absent in L. congesta ; all reports of gemmae in L. congesta (e. g. Arnell 1963; Grolle 1969; Gradstein et al. 1983; Schuster 2021) are erroneous and refer to L. pansa .

Figures

Figure 1. Habit of Lethocolea. A. L. pansa. B. L. congesta. Photos: A by Bruce Fuhrer; B by Jan Peter Frahm.

Figure 3. Cuticle and oil bodies in Lethocolea, SEM. A, D. Papillose cuticle of L. congesta. B. Smooth cuticle of L. pansa. C. Papillose cuticle of L. javanica. E – F. Oil bodies of L. javanica. G – H. Oil bodies of L. congesta. A, D from Larrain 42566; B from Arts 129 / 11; C, E – F from Beckmann (unpublished thesis work, 1985); G – H from from Arts 19 / 54. Photos: A – B, D by Anna Luiza Ilkiu-Borges; C, E – F by Karen Beckmann; G – H by Christine Cocquyt and Robbert Gradstein.

Figure 4. Leaf cells and habit of Lethocolea javanica and L. pansa. A – B. Midleaf cells of L. javanica, showing large trigones. C. Leaf margin cells of L. javanica, showing papillae. D – E. Midleaf cells of L. pansa, showing trigones absent or very small. F. Habit of L. pansa (wetted herbarium material). A – B from Cargill 166; C from Docherty 2; D from Purdie 8216 A; E from Curnow 6597 A; F from Purdie 8216 A. Photos by D. Christine Cargill.

Figure 5. Gemmae of Lethocolea javanica and L. pansa. A – E. Winged gemmae of L. javanica. F – J. Wingless gemmae of L. pansa. A from Streimann 970; B – D from Streimann 49251; E from Curnow 6163; F from Curnow 6871; G from Purdie 8216 A; H from Curnow WA 118; I from Curnow 6567; J from Streimann 54953. Photos by D. Christine Cargill.

Figure 6. Lethocolea pansa. A, G. Female shoot with immature marsupium. B. Female shoot with mature marsupium. C. Cross section of stem. D. Cells at leaf apex. E. Gemma. F. Portion of shoot with gemmae, dorsal view. H, J – L. Leaves. I. Sterile shoot. M. Cells at ventral leaf base. N. Midleaf cells. O. Cells at dorsal leaf base. A, C – E, G – I, M – O from Esterhuysen 27343; B, L from Hedderson 152686; F, J – K from Arts 129 / 11. Drawn by Anna Luiza Ilkiu-Borges.