Notothylas javanica (Sande Lac.) Gottsche, Bot. Zeitung, 1857

Cargill, D. Christine, 2016, Rare and peculiar hornworts: Notothylas orbicularis and N. javanica (Notothyladaceae), new genus and species records for Australia, Phytotaxa 275 (1), pp. 1-13 : 2-5

1. Notothylas javanica (Sande Lac.) Gottsche, Bot. Zeitung (Berlin), 16: 20 (1858)

Blasia javanica Sande Lac., Verhandelingen der Koninklijke Akademie van Wetenschappen. Sect. 2, 5: 94 (1857).

Type: Indonesia, Java., s.dat., D.G. Holle s.n. (holotype L n.v.).

Illustrations: J.Hasegawa, Acta Phytotaxonomica et Geobotanica 30: 24 (1979); H.Stieperaere & H.W.Matcham, Journal of Bryology 29: 4 (2007).

Plants as scattered patches, amongst grasses and herbs, patent, branching dichotomous, fan-shaped, sub-orbicular to orbicular rosettes, up to 6 mm long and 9 mm wide, lobes 0.1–1.3 mm wide, margins entire to + crenate; thallus yellow green (RHSCC 144A, C, 146A, D yellow-green group), becoming dark olive green (RHSCC 147A yellow-green group) when dry. Thallus solid, ecostate, mid thallus up to 11 cells thick (to 560 μm), gradually decreasing in thickness to a single cell at the margins; thallus may contain large mucilage-filled hypodermal cells; varying from plano-convex to elliptic in transverse section, often variable due to presence of ventral radiating keels. Dorsal surface mostly smooth, except over sporophyte region which bears short, finger-like lamellae. Dorsal epidermal cells quadrate to octagonal, 22.5–112.5 (–150) μm x 27.5–67.5 μm, internal cells 82.5–290 μm x 25–125 μm. Ventral epidermal cells quadrate to octagonal, 37.5–125 μm x 22.5–60 μm. Ventral clefts absent. All epidermal cells with a single chloroplast, pyrenoid present. Nostoc colonies absent or sparse (1–2 colonies), appearing as dark dots within the thallus or bulging from the thallus surface. Rhizoids ventral, confined to central keels, both hyaline and granular. Specialised asexual reproduction absent, but thallus with thickened pads between lobes, which may function as tubers.

Monoicous, androecia ± in pairs along dorsal side of thallus keels with up to 4 antheridia per cavity, orange-yellow, spherical or ovoid, jacket cells irregularly arranged, 75–150 x 57–150 μm, stalk from 25–125 μm long. Involucre ventral, horizontal, tubular, 1 mm long, 5 cell layers thick, epidermal surface smooth. Sporogone ventral (none found on the dorsal surface as typically observed for this genus) and growing horizontally along thallus surface not visible beyond thallus margin. Capsule emergent, fusiform or banana-shaped, 1.3–1.6 mm long, lacking specialised sutures or valves, opening by disintegration of epidermal cells, yellow-orange, becoming dark orange with maturity, foot easily detached, bulbous at end of short stalk.Assimilative layer 2 to 5 cells thick, compressed, sporogenous layer of several rows of spores, columella absent. Epidermal cells of capsule quadrate to shortly rectangular, 25–65 μm x 15–55 μm, walls becoming thickened with maturity (5–12.5 μm wide), but with a distinct lumen (2.5–27.5 μm wide), stomata absent. Spores yellow, hemispherical-tetrahedral, in equatorial view, globose in polar view, equatorial diameter 47.5–57.5 μm, polar height 30–40 μm. Spore with a narrow equatorial cingulum, macro-ornamentation lacking on both dorsal and proximal surfaces, micro-ornamentation finely vermiculate, distal surface with a central mamillate projection, proximal triradiate mark distinct, thin. Pseudoelaters absent.

Plates 1–3 .

Distribution:—Widespread. Recorded from Africa ( Democratic Republic of the Congo, Ghana and the Ivory Coast), Asia ( China, Taiwan, southern Japan, the Philippines, and Indonesia), Central America and North America. Known in Australia from a single locality at Fish River Station, 200 km south of Darwin in the Northern Territory.

Etymology:—Named for the type locality, Java, Indonesia.

Specimens examined:— NORTHERN TERRITORY: Fish River Station. 25 April 2012, D.C.Cargill & B.Wirf 1271, 1272, 1273, 1274 (CANB, DNA).

Figures

PLATE 1. Notothylas javanica. a.–b. Plants in situ. c.–d. Ventral view of plants illustrating ventral position of the capsules. e. Whole plant showing ventral branched ‘keels’ of the thallus. f. Single antheridium. Images by D. C. Cargill.

PLATE 2. Notothylas javanica. a. Capsule epidermal cells (short and moderately thick-walled). b. Spores and disintegrated epidermal cells of the capsule. c. Spores and epidermal cells of capsule. d.–f. SEM images of spores. d. Dorsal and ventral view of two spores. e. Distal view of spore. f. Proximal view of several spores. Images by D. C. Cargill.

PLATE 3. Notothylas javanica. a.–e. Single plants—circles are antheridial cavities f. Dorsal epidermal cells of thallus; two cells contain a single chloroplast with an associated pyrenoid. g. Ventral surface of plant with two sporophytes (inv = involucre; caps = capsules). h. Capsule epidermal cells. i. Basal epidermal cells of capsule. j. Internal cells of capsule below the epidermis. k. Antheridium. l. Proximal view of two spores. Illustrations by D. C. Cargill.