Riella affinis Howe & Underwood

Segarra-Moragues, José Gabriel, Puche, Felisa & Gil-López, Manuel Jesús, 2019, A complete description and conservation assessment of Riella affinis Howe & Underwood (Riellaceae, Sphaerocarpales) new to continental Europe, Cryptogamie, Bryologie 20 (23), pp. 297-307 : 300-304

Riella affinis Howe & Underwood

Bulletin of the Torrey Botanical Club 30: 221 (1903).

Riella vishwanathai Pandé, Misra & Srivastava, Revue bryologique et lichénologique 23: 166 (1954). — Type: India. Uttar Pradesh, Lake Latif Shah, in shallow water or along the lake margin, on mud. 1950, K. C. Misra 3590 (4817 LWU!).

TYPE. — Spain. Canary Islands, Grand Canary, Tafira, on the bank of a reservoir, VI.1897, O. F. Cooke 729 (holo-, 01093954 NY!; iso- HBG!, JE!, Krypto-S!, MA-Hepat.!, NY!, YU!).

NEW RECORDS. — Spain. Málaga, Antequera, Laguna de Caja, 37°01’19.88’’N, 4°28’11.01’’W, 729 m, M. J. Gil-López, cultures started on 17 Apr 2018, plants dried on 18.VII.2018. (VAL-Briof. 11.797); Antequera, Laguna de Viso/Jaralón, 37°00’52.56’’N, 4°28’14.87’’W, 724 m, M. J. Gil-López, plants collected on 18. VI.2018, culture continued in the laboratory and plants dried on 03.IX.2018 (VAL-Briof. 11.798).

DESCRIPTION

Plants

0.9-3.5 cm tall, caespitose, bifurcate from the base, rarely unbranched, shoot apex falciform ( Figs 2B , 4A ). Axis slightly flattened 0.16-2.4 mm wide. Dorsal wing 2-2.7 mm wide,

deeply lobed ( Figs 2B , 4A ). Marginal wing cells quadraterectangular, chlorophyllose, 17-47 × 13-22 µm ( Fig. 4E ); wing cells near axis rectangular-polygonal, 107-164 × 23-35 µm; oil cells quadrate, polygonal, 11-31 × 10-27 µm, oil bodies 9-17 × 9-15 µm irregularly spherical, rough, opaque. Scales dimorphic; vegetative scales ligulate to linear-lanceolate, 183- 395 × 66-148 µm ( Fig. 4 B-D); propaguliferous scales panduriform, 389-992 × 220-534 µm. Sexual condition monoicous, protandrous. Antheridia solitary or in groups of 2-12, rarely in larger groups, in sinuses of the dorsal wing ( Figs 2B, C ; 4A ), antheridial body 149-200 × 92-130 µm. Archegonial involucre ellipsoid 1.1-1.9 × 0.9-1.6 mm, blunt to obscurely apiculate, with (7) 8 (10) wings, 217-312 µm high and (4) 7 (11) cells high at their highest part, widest at the middle of involucre, margin entire or undulate-sinuate ( Figs 2 D-F, 4F); some wings interrupted, not reaching the base or apex of involucre. Sporophyte with seta of 0.25-0.42 mm, capsule more or less spherical, 0.64-0.95 × 0.58-0.99 mm.

Spores

106-116 × 100-115 µm in cross diameter including spines, brown, globose, rounded to subtriangular in outline ( Figs 3A, E, G, J ; 4 H-I). Distal face densely covered with 13-15 irregular rows of spines across diameter and interspersed smaller papillae, distance between spines 2.5-5.3 µm, and (30) 32 (34) projecting spines around periphery of equatorial plane ( Figs 3A , G-H, J; 4H-I). Spines (10.6) 12.5 (14.3) µm long (4.1) 5.3 (6.7) µm wide, apices blunt or truncate, with rounded or truncate apices, rarely dilated or flaring ( Figs 3 C-D, I; 4J); basal membranes interconnecting spines below, 0.7-1.3 µm high or absent, sometimes forming imperfect reticulations at the distal pole ( Fig. 3H ); basal membranes at the equatorial plane, 1-2.6 µm high or absent, not forming conspicuous wing-like marginal webbing ( Fig. 3K ). Proximal face flat to convex, without triradiate mark, surface of proximal face rugose ( Figs. 3 J-L; 4I, K); spines dense (distance between spines 1.5- 5.0 µm), shorter than those of distal face (4.5-) 6.9 (-9.5) × (2.3-) 4.2 (-5.7) µm, with blunt or acute apices, not basally interconnected but sometimes joined in clusters, especially towards the periphery of the proximal face ( Figs 3K, L , 4I, K ).

HABITAT

Riella affinis occurred in the shallow (10 cm deep) margins of the Viso lagoon, growing in clearings of areas occupied by Potamogeton gramineus L., Eleocharis palustris (L.) Roem. & Schult. and an unidentified species of Characeae . Water analysis measurements on 18 June 2018 indicated the water was alkaline (pH=8.8) and fresh (0.18 mS/cm, at 35.1°C water temp. at 16:50 h). Based on the results of the culturing of the 2017 soil samples from Caja lagoon, it is likely that R. affinis occurs at greater depth (50-100 cm) in this lagoon ( Fig. 2A ) because the samples were collected when water levels were lower than during the 2018 visit. Here, cultured plants of R. affinis co-occurred with Myriophyllum spicatum L. and a species of the Riella notarisii (Mont.) Mont. complex. Water analysis measurements from Caja lagoon showed that the water was alkaline (pH=9.7), and fresh (0.46 mS/cm, at 33.8°C water temp. at 13:44 h), confirming previous conductivity measurements by Ortega-González et al. (2002). Although R. affinis was not observed in the Chaparral lagoon nor obtained from culture of sediments of this site, the close proximity of this lagoon to the other two and its similar water characteristics (pH=9.1, 0.29 mS/cm, at 28.8°C water temp. at 11:30 h), suggest that the species could also be present here.

Figures

FIG. 2. — Habitat, LM and SEM images of Riella affinis Howe & Underwood: A, habitat at the Caja lagoon; B, one individual showing the lobulate wing; C, thallus apex showing a developing winged female involucre with a sporophyte enclosed and antheridia solitary or in small groups in sinuses of the thallus wing (arrowed); D, E, two female involucres showing the variation in involucre wing morphologies; F, SEM image of female involucre showing an interrupted wing (all from VAL- Briof. 11.797). Scale bars: B, 5 mm; C, 500 μm; D, F, 200 μm; E, 300 μm.

FIG. 4. — Riella affinis Howe & Underwood: A, habit; B-D, vegetative scales; E, cells from margin of thallus wing; F, female involucre; G, cross-section of female involucre showing seven wings; H, spore in distal view; I, spore in proximal view; J, spore spines from distal face; K, spore spines from proximal face. (all from VAL-Briof. 11.797). Scale bars: A, 5 mm; B, C, D, 100 μm; E, 200 μm; F, G, 500 μm; H, I, 30 μm; J, K, 8 μm.

FIG. 3. — LM and SEM images of spores of Riella affinis Howe & Underwood: A, distal view; B, spines and reticulum from distal pole; C, spines from distal side; D, equatorial row of spines; E, proximal view; F, spines from proximal side; G, distal view; H, spines and reticulum of basal membranes at distal pole; I, spines from distal side; J, proximal view; K, transition between distal and proximal side, showing the equatorial row of distal spines; L, proximal spines and rugose spore surface. (all from VAL-Briof. 11.797). Scale bars: A, E, 50 μm; B, C, D, F, 10 μm; G, J, 30 μm; H, 9 μm; I, 5 μm; K, L, 8 μm.