Rhipidosiphon javensis Montagne, 1842

Nguyen, Tu Van, Le, NhuHau & Clerck, FrederiqueSteenand OlivierDe, 2013, Checklist of the marine macroalgae of Vietnam, Botanica Marina (Warsaw, Poland) 56 (3), pp. 207-227 : 221-223

Rhipidosiphon javensis Montagne [76, (9, 11, 53, 58 as Udotea javensis (Montagne) A. Gepp et E. Gepp )] Rhipiliopsis echinocaulos (A.B. Cribb) Farghaly [13] Rhizoclonium grande BØrgesen [50, 53, 58]

Rhizoclonium riparium (Roth) Harvey [9, 27, 50, 53, 58, (9, 11, 35, 50, 53, 58, 59 as Rhizoclonium kerneri Stockmayer )] Rhizoclonium riparium var. implexum (Dillwyn) Rosenvinge [(35, 40, 44, 50, 52, 53, 58, 59 as Rhizoclonium kochianum Kützing )]

Rhizoclonium tortuosum (Dillwyn) Kützing [50, 53] Trichosolen mucronatus (BØrgesen) W.R. Taylor [(11, 53, 58 as Pseudobryopsis mucronata BØrgesen)]

Trichosolen parvus (E.Y. Dawson) W.R. Taylor [(11, 53, 58 as Pseudobryopsis parva E.Y. Dawson )]

Tydemania expeditionis Weber Bosse [7, 10, 43, 53, 60] Udotea argentea Zanardini [53, 58, 61]

Udotea flabellum (J. Ellis et Solander) M. Howe [7, 41, 53] Udotea orientalis A. Gepp et E. Gepp [53, 76]

Udotea velutina C.K. Tseng et M.L. Dong [7, 53]

Ulothrix flacca (Dillwyn) Thuret [53]

Ulothrix subflaccida Wille [58]

Ulva chaetomorphoides (BØrgesen) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope et J.R. Waaland [(50, 52, 53, 58 as Enteromorpha chaetomorphoides BØrgesen)] Ulva clathrata (Roth) C. Agardh [(11, 27, 35, 40, 44, 50, 53, 58, 59, 60 as Enteromorpha clathrata (Roth) Greville ), including f. pumilla ]

Ulva compressa Linnaeus [(50, 53, 76 as Enteromorpha compressa (Linnaeus) Nees )]

Ulva conglobata Kjellman [9, 44, 50, 52, 53]

Ulva flexuosa subsp. pilifera (Kützing) M.J. Wynne [50, 53] Ulva flexuosa Wulfen [(11, 27, 52, 53, 58, 59, as Enteromorpha tubulosa (Kützing) Kützing ), (27, 50, 52, 53, 58 as Enteromorpha flexuosa (Wulfen) J. Agardh )]

Ulva intestinalis Linnaeus [(11, 27, 44, 53, 58, 59 as Enteromorpha intestinalis (Linnaeus) Nees )]

Ulva kylinii (Bliding) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope et J.R. Waaland [(11, 35, 40, 44, 50, 53, 58, 69 as Enteromorpha kylinii Bliding )]

Ulva lactuca Linnaeus [2, 40, 44, 50, 53, 58, 76, (9, 50, 53 as Ulva fenestrata Postels et Ruprecht ), (53, 58 as Ulva fasciata Delile )]

Ulva papenfussii Pham H.H. [40, 44, 53, 58]

Ulva prolifera O.F. Müller [(27, 50, 52, 53, 76 as Enteromorpha prolifera (O.F. Müller) J. Agardh )]

Ulva ralfsii (Harvey) Le Jolis [(10, 35, 53, 58 as Enteromorpha ralfsii Harvey )]

Ulva reticulata Forsskål [2, 40, 44, 53, 58, 76]

Ulva spinulosa Okamura et Segawa [50, 53]

Ulva stipitata Areschoug [(50, 53, as Enteromorpha stipitata var. catbaenis A.D. Zinova et Nguyen H. Dinh , a variety not formally transferred yet to Ulva )]

Ulva torta (Mertens) Trevisan [(50, 52, 53 as Enteromorpha torta (Mertens) Reinbold )]

Ulvella lens P.L. Crouan et H.M. Crouan [53, 58]

Ulvella viridis (Reinke) R. Nielsen, C.J. O’Kelly et B. Wysor [(11, 53, 58 as Entocladia viridis Reinke )]

Valonia aegagropila C. Agardh [9, 10, 11, 44, 50, 53, 58, 76] Valonia fastigiata Harvey ex J. Agardh [40, 44, 53, 58, 76] Valonia macrophysa Kützing [50, 52, 53]

Valonia utricularis (Roth) C. Agardh [10, 53, 58, 60, 61, 76] Valonia ventricosa J. Agardh [11, 44, 53, 58, 60, (76 as Ventricaria ventricosa (J. Agardh) J.L. Olsen et J.A. West)] Valoniopsis pachynema (G. Martens) BØrgesen [50, 53, 58, 59, 69]

Vaucheria piloboloides Thuret [50]

Notes

Sargassum nigrifolium Yendo , S. nipponicum Yendo , S. patens var. vietnamese nom. nud., S. tortile C. Agardh , S. tosaense Yendo were removed from the Vietnamese flora on the authority of Yoshida (2002a). Sargassum polycystum var. longicaule was removed on the authority of Nguyen H. Dai (1997, 2007).

The following species are not included in the checklist because they have not been formally described: Ceramium phuquocense nom. nud. [59], Gigartina vietnamensis nom. nud. [50], Solieria fastigiata nom. nud. [45, 69], Caulerpa minuta nom. nud. [21] and Chaetomorpha patentiramea nom. nud. [9].

Year

Diversity of marine macroalgae in Vietnam

The present checklist contains a total of 827 species (180 Chlorophyta, 147 Phaeophyceae, 412 Rhodophyta and 88 Cyanobacteria) compiled from all earlier species records in both international and Vietnamese publications. This work represents the most inclusive list of Vietnamese flora to date, including 623 species more than in Dawson’s first list ( Dawson 1954), and 157 species more than reported on Algaebase ( Guiry and Guiry 2012). This checklist offers an up-to-date overview of Vietnamese algal flora and considerably improves its accessibility to the international community. Importantly, the checklist provides currently accepted species names for Vietnamese seaweeds. Continuous taxonomic refinement means that a considerable proportion (> one third) of taxon names listed in earlier publications, such as Dawson (1954), Pham H.H. (1969) and Nguyen H. Dinh et al. (1993), are no longer considered currently accepted.

The bulk of new records of seaweeds from Vietnam were published in a few publications only (e.g., Dawson 1954, Pham H.H. 1969 and Nguyen H. Dinh et al. 1993). Despite an increase in the number of algal publications from the 1990s onward, the discovery rate of new records seems to diminish ( Figures 1 and 2 ). From this, the question arises whether we are getting close to documenting most of the Vietnamese seaweed diversity. Previous diversity estimates resulted in a figure of nearly 1000 seaweed species for the Vietnamese coast (Huynh and Nguyen H. Dinh 1998, Dang et al. 2007). In contrast, Algaebase reports only 670 taxa ( Guiry and Guiry 2012), but this figure is only indicative as a number of publications were not included yet (e.g., Pham H.H. 1985, Nguyen H. Dinh et al. 1993, Nguyen H. Dai 1997, Nguyen H. Dai et al. 2000, Nguyen H. Dai and Pham H.T. 2003, Le N.H. 2000, 2001, 2004, Dam 2003, Le N.H. and Nguyen H. Dai 2006, Nguyen V. Tien 2007).

Distribution of seaweeds along the Vietnamese coast

Locality data have been included in the database of Vietnamese seaweeds, enabling us, to some extent, to analyse biogeographic and richness patterns ( Figure 3 ). Of the 20 studied provinces, 12 have over 100 species, of which two are northern provinces (Quang Ninh, Hai Phong), seven are central provinces (Thanh Hoa, Quang Tri, Da Nang, Quang Ngai, Khanh Hoa, Ninh Thuan, Binh Thuan) and two are southern provinces (Ba Ria - Vung Tau, Kien Giang). Totals of 60 and 197 species are reported from the offshore Paracel and Spratly islands, respectively. The greatest species number (418) has been reported for the Khanh Hoa province, where half of the total number of species in Vietnam have been found. In general, the highest marine macroalgal diversity has been recorded for the South Central Coast region. The differences in species diversity among the provinces and regions are most likely influenced by differences in research efforts. The South Central region has traditionally been the most extensively investigated region. At least one-third of the publications on Vietnam’s seaweed flora focus on the Khanh Hoa province or its vicinity. This region was popular with visiting international phycologists (e.g., Dawson 1954, Abbott et al. 2002, Tsutsui et al. 2005). However, the high diversity might be sustained by the habitat heterogeneity of this region, or by increased primary productivity caused by local upwelling.

Diversity of marine macroalgae in Vietnam compared to neighbouring countries

The diversity of the Vietnamese seaweeds was compared with those of a number of neighbouring countries ( Malaysia, Philippines, Taiwan and Thailand). The Philippines appear to be the most diverse country with a staggering total of 1011 species, whereas Vietnam harbours a comparable 827 species ( Figure 4 ). SØrensen similarity indexes are low (C s <0.5; Table 1). These low values are counterintuitive. Within similar climatic zones and in the absence of major dispersal barriers, marine biodiversity is expected to be much more homogenous (see Spalding et al. 2007). Even though we cannot rule out the existence of a biogeographical pattern making the Vietnamese seaweed flora highly distinct, we are of the opinion that the low similarity with neighbouring countries is primarily an artifact resulting from taxonomic inconsistencies. The checklist presented here could serve as a valuable

Figures

Figure 1 Numbers of publications on Vietnamese seaweeds (green line, right axis) and numbers of new algal records reported (bar chart, left axis) by year between 1954 and 2010.

Figure 2 Cumulative curve of new species records from Vietnam.

Figure 3 Distribution of seaweeds by province along the coast of Vietnam.

Figure 4 Numbers of species of seaweeds in Vietnam and neighbouring countries.