Riella choconensis Hässel

Segarra-Moragues, José Gabriel, Puche, Felisa & Gleiser, Gabriela, 2019, Study of a new population of the Argentinian endemic species Riella choconensis Hässel (Riellaceae, Marchantiophyta) reveals a novel anatomical structure of the female involucre in Riella, Cryptogamie, Bryologie 20 (12), pp. 131-140 : 134-138

Riella choconensis Hässel

In Symposia Biologica Hungarica 35: 341 1987

TYPE. — Argentina, Prov. Neuquén, Embalse Mexía, estación de muestreo A 10, bentos, F. Kaysin, 7. I.1984 (holo-, BA [ BA 33608]; para-, BA [ BA 33609]!).

NEW RECORD. — Argentina, Prov. Río Negro, Laguna de Los Juncos, 19GCQ 3152, 910 m, sediments collected on 15.IX.2016, G. Gleiser s.n., cultures started on 15.X.2016, plants dried 23.II.2018 (VAL-Briof. 11724); plants dried 16.IV.2018 (VAL-Briof. 11725); plants dried 6. VI.2018 (VAL-Briof. 11726); plants dried 4.VII.2018 (VAL-Briof. 11727).

Plants

2.5-5.7 cm high, unbranched or bifurcate ( Fig. 4A, B).

Axis

Slightly flattened 209-336 µm wide. Dorsal wing single, undulate or helicoid ( Fig. 4 A-B), 1.3-2.3 mm wide.

Marginal cells

From wing rectangular, chlorophyllose, 28.5-58.6 × 14.4- 30.2 µm ( Fig. 4F).

Cells

From mid wing polygonal, 43.28-77.44 × 23.35-41.89 µm ( Fig. 2C ); cells from wing near axis, 71.0-172.1 × 18.0-33.1 µm.

Oil cells

11.7-33.1 × 13.0-28.8 µm quadrate-rectangular, oil bodies 7.4-24.1 × 8.8-24.4 µm spherical, rough, opaque ( Fig. 2C ).

Scales

Dimorphic; vegetative scales ligulate, linear or lanceolate, 220.2-493.1 × 87.9-238.3 µm ( Fig. 4C, D).

Propaguliferous scales

Panduriform, 171.8-487.3 × 107.8-269.1 µm ( Fig. 4E).

Sexual condition

Dioicous; male plants similar in size to female plants.

Antheridia

In large continuous series or in small groups ( Figs 2B , 3A ); antheridial body 263.5-415.3 × 128.9-190.2 µm.

Female involucre

Ellipsoid, acuminate, 999.8-1721.4 × 941.1-2200.5 µm, smooth or with cells slightly bulging ( Figs 2 D-E, 4 G), with base partially sheathed by a larger vegetative scale ( Figs 2 D-E, 4 B). Apex of female involucre occluded, with bulging cells ( Fig. 2F , H-I); involucre wall bistratose in cross-section ( Figs 2G ; 4H).

Sporophyte

With seta of 227.7-366.5 µm long, capsule globose, spherical, 838.4-1186.1 × 830.9-1213.0 µm in diameter ( Figs 2E , 4G).

G F B H A E I D K C J

Spores

(121.6-)132.8(-141.3)×(117.2-)127.1(-139.8) µm, and (102.1-)107.8(-116.3)×(99.0-)104.3(-116.7) µm including and excluding spines, respectively, dark brown, subspherical, tetrahedral, circular to subtriangular in outline ( Fig. 3A, D, G, J, M, P ).

Distal face

With 14-17 irregular rows of spines across diameter, and 32-39 spines projecting at periphery at the equatorial plane ( Fig. 3A, D, G, J ), surface of distal face rugose ( Fig. 3I, L ).

Spines

(9.5-)12.3(-15.2) µm long, (4.5-)6.0(-7.6) µm wide ( Fig. 3I, L ), with blunt or acute apices ( Figs 3B, E, I, L ; 4 I-J), basal membranes interconnecting spines restricted to distal pole, faint ( Fig. 3 G-H, J-K), distance between spines shorter than the length of the spine (3.7-)6.2(-9.13) µm.

Proximal face

With rugose, sometimes granulose surface ( Fig. 3 N-O, Q-R), triradiate mark indistinct, spines of proximal face conical, with smooth surface; shorter than those of distal face, (4.1-)6.5 (-8.9) µm long, (3.8-)4.8,(-6.2) µm wide, generally with acute apices, rarely blunt or truncate, not basally interconnected ( Figs. 3 N-O, Q-R; 4 K), distance between spines (2.2-)6.1 (-12.7) µm.

HABITAT

In the new locality, it is likely that R. choconensis occurs submerged in areas of shallow water as plants were obtained from sediments collected at the margins of the pond. Species simultaneously obtained from these cultures and thus, presumably co-occurring with R. choconensis were: Limosella australis R.Br. ( Plantaginaceae ), Myriophyllum quitense Kunth ( Haloragaceae ), Zannichellia palustris L. ( Potamogetonaceae ) and species of Characeae .

Figures

FIG. 2. — Habitat, LM and SEM images of Riella choconensis Hässel A, view of the Laguna de los Juncos; B, circinate apex of a male individual thallus showing a continuous row of antheridia; C, cells from thallus wing showing an oil cell with a single, rough oil body; D, apex of a female individual thallus showing three developing sporophytes; E, female involucre enclosing a sporophyte; F, apex of female involucre occluded by inflated cells; G, cross-section of female involucre showing the bistratose wall; H, female involucre; I, Apex of female involucre (B-G made with LM from VAL-Briof. 11724; H,I made with SEM from VAL-Briof. 11725), Scale bars: B, D, 1 mm; C, 20 μm; E, 500 μm; F, 200 μm; G, 50 μm; H, 300 μm; I, 70 μm.

FIG. 3. — LM and SEM images of spores of Riella choconensis Hässel. A, distal view; B, spines from distal side; C, spines from proximal side; D, distal view; E, spines from distal side; F, spines from proximal side; G, distal view; H, Spines and reticulum from distal pole; I, spines from distal side and rugose spore surface;J, distal view;K, spines and reticulum from distal pole; L, spines from distal side and rugose spore surface; M, proximal view;N, proximal spore surface and spines; O, proximal spines and rugose-granulose spore surface; P, Proximal view; Q, transition between distal and proximal side, showing the equatorial row of distal spines; R, Proximal spines and rugose spore surface (A-F made with LM; G-R made with SEM; A-C, I, from VAL-Briof. 11724; G-H, M-O, from VAL-Briof. 11725; D-F, J-L, P-R, from BA 33609). Scale bars: A, D, 50 μm; B, C, E, F, H, K, N, Q, 10 μm; G, J, M, P, 30 μm; I, L, O, 5 μm; R, 8 μm.