Lethocolea subgen. Lethocolea, Mitt.

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

I. Lethocolea subgen. Lethocolea

Lethocolea sect. Lethocolea

Description.

Stems ventral surface green or dark purplish-reddish pigmented; stolons present or absent. Leaf cells with smooth or densely papillose cuticle; oil bodies one per cell (Fig. 3 E, F ), ellipsoid, ca 10–25 µm long, greyish-brown, rarely colourless ( L. naruto-toganensis ), finely papillose, sometimes with 1–3 pupils or “ eye spots ” (= larger and lighter-coloured granules). Antheridia one per bract. Marsupia usually long and slender, narrowly cylindrical, (3 –) 8–15 mm long, when mature with swollen tip (Fig. 6 B ), wall 5–6 cells thick, marsupial canal lined by numerous elongate, papilliform cells that nearly fill the canal. Capsules splitting to the base into 4 valves. Asexual reproduction by disciform gemmae produced near the shoot apex on the dorsal surface of the stem or on the base of dorsal leaf margins ( L. naruto-toganensis ), gemmae 4–20 cells across, 0.1–0.5 mm in diameter, biconvex, becoming thinner to the margin and sometimes with a 1–2 cell wide unistratose, transparent wing.

Distribution.

Three species in Australasia, Java, India, Japan, and South Africa.

Figures

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 A, D from Larrain 42566; B from Arts 129 / 11; C, E – F from Beckmann (unpublished thesis work, 1985); G – H from from Arts 19 / 54.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 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.