Rediscovery of Riella Alatospora

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South African Journal of Botany 79 (2012) 32–38 www.elsevier.com/locate/sajb

Short communication Rediscovery of Riella alatospora (Riellaceae, Sphaerocarpales), an aquatic, South African endemic liverwort previously known from a now largely transformed type locality ⁎ J.G. Segarra-Moragues a, , F. Puche b, M. Sabovljević c

a Centro de Investigaciones sobre Desertificación (CIDE-CSIC-UV-GV), C/ Carretera de Moncada-Náquera Km 4.5, Apartado Oficial, E-46113, Moncada (Valencia), Spain b Departamento de Botánica, Facultad de Ciencias Biológicas, Universitat de València. C/ Dr. Moliner s/n. E-46100, Burjassot (Valencia), Spain c Institute of Botany and Garden, Faculty of Biology, University of Belgrade, Takovska 43, RS-11000, Belgrade, Serbia

Received 5 September 2011; received in revised form 21 November 2011; accepted 23 November 2011

Abstract

Riella alatospora is reported from cultured sediments from a salt pan near Springfield (Western Cape), South Africa. This species was previously known only from the type locality near Cape Town, and has not been collected since 1932. Because the original locality has been severely affected by urbanization in the past decades, the species is unlikely to survive there. The identity of the specimens obtained from the cultured sediments were confirmed by comparison with the type material of R. alatospora. A detailed description of R. alatospora including lectotypification, illustrations, light and scanning electron microscopy micrographs of spores, and an updated distribution map is presented. Our finding suggests that the genus Riella is likely to be more widespread in South Africa than previously thought and that extensive sampling is required before an accurate distribution of the species can be ascertained. This study also highlights the value of culture sediments in revealing the presence of Riella. © 2011 SAAB. Published by Elsevier B.V. All rights reserved.

Keywords: Aquatic liverworts; Bryophytes; South Africa; Southern Hemisphere; Spore morphology

1. Introduction Furthermore, their specialised aquatic habitat offers very little of in- terest to bryologists, apart from Riella, and so they are often over- The genus Riella Mont. (Riellaceae, Sphaerocarpales) includes looked. It is not surprising then that some populations and even some 22 species of aquatic thallose liverworts and is distributed species have been discovered from cultures aimed at sampling in areas of Mediterranean or subdesertic climate types on all conti- ponds and lagoons for other organisms like crustacean (Cavers, nents except Antarctica. Their small size, ephemeral aquatic habi- 1903; Hässel de Menéndez, 1979; Perold, 2000; Porsild, 1902). tat, and dependence on the nature of the flooding season makes Five species of Riella (R. affinis M. Howe & Underw., R. alatos- finding populations somewhat difficult. Populations are generally pora Wigglesworth, R. capensis Cavers, R. echinospora Wiggles- demographically fluctuant, with some years experiencing sudden worth and R. purpureospora Wigglesworth) are present in demographic blooms and other of complete absence, as population southern Africa (Perold, 2000; Wigginton and Grolle, 1996; growth may be inhibited both by too high or too low water levels. Wigginton, 2009).Ofthesefivespecies,R. affinis a monoecious species of subgenus Trabutiella has the widest distribution range, and is the only species reported outside southern Africa (Howe and Underwood, 1903; Patel, 1977; Puche and Boisset, 2009; ⁎ Corresponding author. Tel.: +34 963424126; fax: +34 963424160. Thompson, 1940). However, within South Africa this species is E-mail address: [email protected] (J.G. Segarra-Moragues). still known only from a single reported locality (Proskauer,

0254-6299/$ -see front matter © 2011 SAAB. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.sajb.2011.11.006 J.G. Segarra-Moragues et al. / South African Journal of Botany 79 (2012) 32–38 33

1955). The remaining four species belong to subgenus Riella,shar- BIORAD SC-500 ion sputtering coater. Morphological observa- ing the smooth female involucres. Riella echinospora is known tions were carried out in a Hitachi S-4100 field emission scanning from only two isolated localities, the one in South Africa electron microscope (SEM) at the University of Valencia (SCSIE- (Wigglesworth, 1937) and the other in Namibia (Arnell, 1957); UV). Terminology for spore characters follows Perold (2000). R. purpureospora is endemic to South Africa and is the only species reported in recent times (Harding et al., 2000; Perold, 2000) 3. Results around the Cape Town area. The two remaining species R. capensis Cavers and R. alatospora Wigglesworth were both known only In May 2011 the first germlings of Riella appeared in the cul- from one locality (Cavers, 1903; Wigglesworth, 1937). Some other tures, just two months after the flooding of the sediments with dis- existing reports of Riella from South Africa (Perold, 2000; tilled water. Gametophyte development continued during the two Wigglesworth, 1937)andNamibia(Arnell, 1957) have not been following months until the first reproductive organs were visible. assigned to any of these species because of the absence of mature The individuals corresponded to a dioecious species and males spores which are essential for species identification whereas others were the first to reach maturity. Two weeks later female individ- have been tentatively assigned to R. capensis (Coetzer, 1987), but uals began to develop involucres after the fertilization of the arche- have not been verified in recent revisions of the genus (Perold, gonia and sporophytes contained ripe spores by the end of August 2000). 2011. The spores of these individuals were compared to those pre- Riella alatospora was originally collected by Dr. E.L. Ste- sent in the original cultured material used for the description of R. phens from a vlei (pond) in Salt River, Cape Town in 1932 alatospora (Wigglesworth, 1937). Both samples showed spores and sent to Manchester where it was studied by Dr. G. Wiggles- triangular in outline and with a conspicuous wing around the equa- worth who described it after the presence of a wing along the torial plane, short truncate spines on the distal face and short acute equatorial plane of the spores. This original locality has been spines over a flattened central dome on the proximal face. These severely altered by urbanizing activities, as have many parts distinctive spore characters allowed for the unambiguous place- of the city area (Rebelo et al., 2011), to the point that it is un- ment of the cultured specimens with that of R. alatospora (Fig. 1). likely that populations of this species are currently developing A detailed description of R. alatospora was provided by there. As a result, R. alatospora has not been collected or Wigglesworth (1937) including developmental stages observed reported for more than 80 years (Perold, 2000). in the laboratory and later by Perold (2000) from herbarium As part of a world-wide study of the genus Riella, sediments material. Here we supplement those descriptions with individu- from a salt pan at Springfield, near Cape Agulhas were collect- al characters from this new collection. ed by the first author during February 2010. Cultures of those sediments rendered plants of Riella in an area not previously in- 3.1. Riella alatospora cluded in the known distribution ranges for any of the South African species. Wigglesworth in J. Linn. Soc., Bot., 5: 317 (1937). Type: South Africa. Western Cape, Cape Town (3318), ‘vlei at Salt River be- 2. Materials and methods tween main road and railway line’ (−CD), 1932, E. L. Stephens s.n. (CC 1627 MANCH! lecto.; BOL, iso.). [Note: Grace Wiggles- About 0.5 kg of dried sediments were collected from several worth received a specimen of R. alatospora from E. L. Stephens points in one side of the salt pan and included the first 5 cm and then cultured the plant further from spores. Apparently, both depth of soil. Collection points were located just a few meters wild and cultivated materials were used in the original description from the shore line and where visible dried debris of plants and of this species with no explicit designation of a holotype in algae had accumulated. Sediments were kept on a zip plastic Wigglesworth (1937). Contrary to other South African specimens bag in the laboratory at room temperature. One year after collec- of Riella reared in the laboratory by Wigglesworth, the material of tion of soil samples the sediments were flooded with distilled R. alatospora (CC 1627) was not labelled as having been derived water in the laboratory. The cultures were turbid after this initial from cultures and rather represents the duplicate of the original flooding and two subsequent water changes were required until Stephens' collection in BOL (not located). As such the specimen they were transparent. These changes were conducted without in MANCH is here designated as the lectotype.] disturbing the sediments and any visible germination that could Plants 11–18 (20) mm tall, erect, caespitose, usually bifurcate have occurred. from the base and 2 to 3 branched above, becoming shrubby, rarely Measurements of vegetative and spore characters were taken unbranched (Figs.2,3B,C). Thallus apex falciform. Axis slightly using the interactive measurement module of Leica Application flattened, 0.15–0.22 mm wide. Dorsal wing 0.8–2.1 mm wide, un- Suite (LAS) v. 3.8 (Leica microsystems, Barcelona, Spain) cali- dulate, margin entire, marginal cells quadrate or oblate, the first brated to the nearest 0.01 μm on digital images. All measurements 5 to 7 rows of cells hyaline (Figs. 2D, 3F), 15–41×14–34 μm; were taken under a Leica DMLB 100S light microscope, except cells from middle part of wing polygonal 38–70×30–55 μm; for the size of gametophytes and width of wing from the thallus cells from wing near axis rectangular or hexagonal 58–123× that were taken under a Leica M76 stereomicroscope. A Leica 28–75 μm; oil cells 14–26×17–28 μm, oil bodies 12–20× DFC425 digital camera was used for producing high resolution 14–22 μm spherical or ovoid, opaque, smooth. Vegetative scales images. Mature spores were mounted directly on stubs using lanceolate-triangular 313–1015×185–805 μm, arranged in two double-sided adhesive tape and coated with gold/palladium in a lateral rows, opposite (Figs. 2C, 3E). Propaguliferous scales not 34 J.G. Segarra-Moragues et al. / South African Journal of Botany 79 (2012) 32–38

Fig. 1. Light and scanning electron microscopy photographs of spores from Riella alatospora. (A, D) Equatorial plane; (B, G) distal face; (E, H) proximal face; (C, I) detail of wing; (F, J) detail of centre of distal face showing the reticulation formed by basal membranes joining spines; (K) detail of spines from distal face; (L) detail of spines from proximal face.. Vouchers: A, C, D, Stephens s.n. sub comp. cat. 1627 (MANCH); B, E–L, Segarra-Moragues s.n. sub VAL-Briof. 9196 (VAL). seen. Dioicous; male plants equal in size to female plants or Spores 102–127×100–118 μm including spines, orange- larger. Antheridia numerous, continuous, in a single linear series brown to golden brown, triangular, winged (Figs. 1A–E, G–I, in pockets along thickened wing margin or in discontinuous groups 2F–G). Distal face covered with 14 to 18 irregular rows of spines of 12 to 18 to 60, rarely solitary (Figs. 2A, 3B); antheridial across diameter and 24 to 32 projecting spines at periphery at the body 190–230×95–135 μm. Archegonia on axis, produced in equatorial plane (Fig. 1A–B, G, J). Spines (4) 6 (7.1) μmlong acropetal sequence. Archegonial involucre sessile to shortly pedun- (2) 3.6 (5.9) μm wide, apices truncate, and some dilated at the api- culate, globose, ovoid, abruptly narrowed above capsule, rostrate, ces (Fig. 1K). Basal membranes interconnecting spines of centre beaked, 1.5–2.0×0.9–1.2 mm, smooth to slightly papillose of distal face, forming imperfect reticulation and becoming indis- (Figs. 2E, 3C,D); mouth of involucre with apical pore not occlud- tinct towards marginal wing (Fig. 1B, G, J). Wing (10.9) 18.2 ed. Sporophyte with seta of 0.1 mm. Capsule globose, 0.7–0.8 mm (25) μm wide, furrowed (Fig. 1A, C, H-I). Proximal face concave in diameter. with spore body appearing as a raised central dome (Fig. 1E, H-I), J.G. Segarra-Moragues et al. / South African Journal of Botany 79 (2012) 32–38 35

Fig. 2. Riella alatospora. (A, B) General habit of female and male plants, respectively; (C) vegetative scale; (D) detail of cells from margin of thallus wing; (E) female involucre; (F, G) spores on distal and proximal view, respectively. Voucher: Segarra-Moragues s.n. sub VAL-Briof. 9196 (VAL). granulose (Fig. 1E, H–I, L). Triradiate mark indistinct; spines of 3.3. Conservation status proximal face (2) 2.7 (4.1) μmlong(1)1.6(2.6)μmwideμm, with papillose-ganulose apex (Fig. 1L). The lack of collections of R. alatospora since its discovery in the Cape Town area in 1932 justified its inclusion in the IUCN Red List of threatened species under the category of Data Deficient 3.2. Habitat and distribution (DD) by Cholo and Foden (2006). It is probable that because of se- vere urban transformations of the type locality (Rebelo et al., 2011) Known only from two seasonal salt pans in Western Cape, to- the species no longer exists there. Nonetheless, other potential sites gether with species of Characeae and Zannichelliacae (Fig. 4). around the Cape Town area should be screened for the presence of 36 J.G. Segarra-Moragues et al. / South African Journal of Botany 79 (2012) 32–38

Fig. 3. Habitat and appearance of Riella alatospora from Springfield. (A) dried salt pan where the sediments were collected. A whitish line a few meters from the shore-line composed of the accumulation of dried debris of plants and algae is visible; (B) male plant; (C) female plant; (D) detail of female involucre; (E) vegetative scale; (F) detail of cells from margin of wing showing the conspicuous rows of hyaline cells from margin. B–F from VAL-Briof. 9196 (VAL). this species as well as the endemic R. purpureospora, that inhabits mitigate against alterations to the habitat that could compromise similar brackish habitats (Harding et al., 2000). The new Spring- the survival of the plants. The new population occurs within the field population of R. alatospora reportedhereinprovidesanex- boundary of the Cape Agulhas National Park which should confer cellent opportunity to initiate conservation activities aimed at habitat protection and conservation. The abundance of seemingly deciphering actual extension and abundance of individuals and suitable habitats in the surrounding area, including the Cape J.G. Segarra-Moragues et al. / South African Journal of Botany 79 (2012) 32–38 37

periods of desiccation (Harding et al., 2000; Proctor, 1972). Riella alatospora must have been very abundant as many plants were reared from as little as 0.5 kg dried sediment collected from one side of the salt pan (Fig. 3A). However, some cultures of sediments may not be as successful as others (Hässel de Menéndez, 1987; Proctor, 1972) and care should be taken in the selection of the place they are collected from (Proctor, 1972). Usually the most promising place is just a few meters from the shore line and where visible dried debris of plants and algae have accumulated (Fig. 3A). Our finding of R. alatospora from cultures of dried sediments from a South African salt pan in an area far apart from the type locality suggests that the genus and species must be more widespread than previously thought. Similarly, other species and populations of Riella have also been discovered accidentally following this same procedure (Marín, 1982)fromcultureseither specifically designed for the study of Riella (Wigglesworth, 1937) or for the study of other organisms such as Crustacea (Hässel de Menéndez, 1979; Porsild, 1902). Indeed, some species of Riella have still not been discovered growing in the wild and are known only from laboratory reared specimens. This is true for the Argentinian R. pampae Hässel de Menéndez and R. undu- lata Hässel de Menéndez (Hässel de Menéndez, 1979, 1987)but also for some South African species such as R. capensis (Cavers, 1903)orR. purpureospora (Wigglesworth, 1937)andtheAsian R. paulsenii Porsild (Porsild, 1902) for which their presence in the wild has been only sporadically confirmed in relatively recent times (Coetzer, 1987; Harding et al., 2000; Ladyzhenskaja and Obuchova, 1956). While this lack of knowledge may indicate the need for more specific sampling, the strong demographic fluc- Fig. 4. Map showing the known distribution of Riella alatospora. Black circle=type tuations of Riella populations (Griffin, 1961; Proctor, 1972; locality, black star=new locality. Studhalter, 1933) represent a major challenge in establishing their precise distributions and abundance. Agulhas National Park boundary and private-owned lands, suggests that further searches may reveal additional populations. Al- ternatively, translocation of sediments from this locality to other Acknowledgements potentially suitable salt pans within the protected area would allow the establishment of reservoir populations for R. alatospora. We are indebted to F. Ojeda (University of Cádiz) for his help in the field work and L. Loughtman (MANCH) for the loan of the 3.4. Additional specimens examined specimens of R. alatospora. A.J. Ibáñez, P. Gómez, M.T. Mín- guez, and E. Navarro (SCSIE-UV), for their help in SEM analy- South Africa. WESTERN CAPE. 3419 (Caledon), Spring- sis; two anonymous referees and the editor A.R. Magee for their field, near Cape Agulhas, on a salt pan (−DD), 24 Feb 2010, useful comments on a previous version of the manuscript. JGS-M J.G. Segarra-Moragues s.n. sub VAL-Briof. 9196 (VAL). and MS were supported by a Spanish Ministry of Science and In- novation Ramón y Cajal postdoctoral contract and a research stay 4. Discussion from Serbian Ministry of Science and Technological Develop- ment (Grant 173030), respectively. Our study has revealed another locality for R. alatospora and the rediscovery of this species, which has not been reported References since its description in 1937 (Perold, 2000; Wigglesworth, 1937). The new locality is within the Agulhas National Park Arnell, S.W., 1957. Hepaticae collected in South West Africa by Prof. Dr. O.H. and represents a considerable extension of the known distribu- Volk. Mitteilungen der Botanischen Staatssammlung München 16, 262–272. tion of this species. It is likely that, as in other species of the Cavers, F., 1903. A new species of Riella (R. capensis) from South Africa. – genus, R. alatospora only develops in favourable years and Revue Bryologique 30, 81 84. Cholo, F., Foden, W., 2006. Riella alatospora. IUCN 2011. IUCN Red List of thus, the plants obtained in culture may have been derived Threatened Species. Version 2011.1www.iucnredlist.org. from spores produced during the previous growing season or Coetzer, A.H., 1987. Succession in zooplankton and hydrophytes of a seasonal even from older seasons, owing to their resistance to long water on the West coast of South Africa. Hydrobiologia 148, 193–210. 38 J.G. Segarra-Moragues et al. / South African Journal of Botany 79 (2012) 32–38

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Edited by AR Magee