Article

The Genus Chondria C Agardh (Rhodomelaceae, Rhodophyta) in Southern Australia

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Abstract

The genus Chondria is well represented on the coast of southern Australia where 17 species occur. Of the 12 species previously recognised, three are transferred to other genera and two placed into synonymy with other species of Chondria. A further seven species are described as new (C. angustissima, C. capreolis, C. hieroglyphics, C. incurva, C. myriopoda, C. semzsecunda and C. suprabulbosa), one species is raised from subspecific status, one transferred from Coeloclonium and one species from California is described as a new record for southern Australia. Most southern Australian species of Chondria appear to be clearly defined; however, a few intergrades between C. curdieana and C. capreolis occur. Previous confusion in the identification of species was mainly due to the lack of detailed investigation of morphology together with insufficient understanding of important characters and the degree of variation. Only seven of the southern Australian species of Chondria have a wide distribution, one western, one central and eight with primarily eastern distributions. Of the last, two species extend into warm temperate and subtropical waters. Six species are found mainly in deep water (more than 10 m deep) while another six range from shallow to medium depths (less than 10 m deep). The remainder occur in the exclusively shallow water environments of the lower eulittoral to upper sublittoral zones.

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... The genus Acanthophora J.V. Lamouroux 1813 is a member of the tribe Chondrieae and it is distinguished from other genera of the tribe by the presence of spirally arranged acute spines (Gordon-Mills and Womersley 1987). The genus is widely distributed in tropical regions with 7 currently accepted species (de Jong et al. 1999). ...
... Likewise, the validation of morphological characters for species delimitation in the genus, such as apical zone morphology and other vegetative traits, awaits the inclusion of more species in future molecular analyses It is worth noting that with the addition of new COI-5P sequences of A. spicifera (the generitype) from the Western Atlantic, A. pacifica, the only flattened species of the genus, clustered with a pacific sequence of Chondria dangeardii E.Y. Dawson, suggesting that the genus Acanthophora should be emended to comprise only cylindrical species. Previous molecular studies have also shown that A. pacifica is not phylogenetically related to A. spicifera from Hawaii (Kurihara et al. 2010, Sherwood et al. 2011, Diaz-Tapia et al. 2017. A. pacifica was transferred from Cladhymenia pacifica Setchell by Kraft (1979) and uncertainty about its taxonomic placement has been pointed out by several authors (Gordon-Mills and Womersley 1987, de Jong 1999, Perrone et al. 2006, N'Yeurt and Payri 2010. ...
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We record Acanthophora dendroides Harvey for the first time in the Atlantic Ocean. Two specimens from the Philippines were resolved as conspecific to the Atlantic A. dendroides in molecular analyses extending its geographic range to the Philippines. In light of new evidence provided by field-collected specimens of Acanthophora spicifera (M.Vahl) Børgesen (generitype) from Florida and Venezuela, the flattened species A. pacifica (Setchell) Kraft, showed no affinity to Acanthophora sensu stricto, suggesting that the genus should be restricted to cylindrical species only.
... The genus Chondria currently includes some 50 species, which are distributed in tropical and warmtemperate regions in the world and have minute-to large-sized thalli depending on species, and each species is characterised by a particular combination of morphological features (Gordon-Mills and Womersley 1987, Millar and Wynne 1992, Lee and Yoon 1996. The overall size of thalli, the transverse-sectional profile of axes and branches, and the shape of apices of axes and branches are generally important taxonomic features (Millar and Wynne 1992). ...
... Chondria curvilineata, reported from tropical regions in the world (Silva et al. 1987, Wynne 1998, has larger axes 1-3 cm high and 200-500 µm in diameter (Schneider and Searles 1991). Chondria curvilineata and C. decidua are distinguished from each other by the position of cell wall thickenings that is one of the important taxonomic features (Gordon-Mills and Womersley 1987): the former regularly produces cap-like thickenings on the distal wall of pericentral cells (Collins and Hervey 1917), whereas the latter regularly produces lenticular thickenings on the lateral wall of pericentral cells (distal cap-like thickenings being rare). ...
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... The large, robust, mat-forming tendency of C. tumulosa, combined with its terete axes and bluntly rounded apices, set it apart from all other currently recognized species. Many Chondria species are either small, slender, epiphytic, and/or have flattened axes or pointed apices, all of which are characters that differ markedly from the alga collected from PHA [27,28,29]. However, a few species bear some similarity to the new species and are worthy of more direct comparison. ...
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... It is a small, inconspicuous species forming turfs on mangrove pneumatophores together with other minute species which are often covered with a thin coat of mud causing them to be overlooked by inexperienced collectors. In fact, it is suggested to have a wider distribution throughout the tropical and warm temperate regions occurring mainly in the intertidal and subtidal zones [3,22]. It is therefore surprising to find this species, but the ecology and wider distribution made favorable in the study area where many turf-forming species including C. intertexta form close associations with host mangrove species, thereby contributing to the high primary productivity there. ...
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... Compared to vegetative fragmentation, even without the predatory and environmental pressures, vegetative propagules generally persist in a variety of red algae with diverse origins and morphologies. For example, vegetative propagules derived from Chondria tetrasporophytes exhibit different morphological features and sizes (Gordon-Mills & Womersley, 1987;Lee & Yoon, 1996;Maggs & Hommersand, 1993;Tani et al., 2003). However, a few species of Asparagopsis and Polysiphonia produce various forms of vegetative propagules derived from male and/or female gametophytes (Maggs & Hommersand, 1993;Mairh, 1977). ...
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... The monospecific genus Cladurus, endemic to Australia, was included in the tribe Chondrieae in earlier classifications (Falkenberg 1901, Hommersand 1963. However, Gordon-Mills and Womersley (1987) and Womersley (2003) considered that it did not belong to this tribe because spermatangial branches are cylindrical instead of plate-like, as is characteristic in the Chondrieae. Furthermore, this genus is distinguished from other Rhodomelaceae by its terete thalli with five pericentral cells, pseudoparenchymatous construction with light cortication so that the segments are conspicuous in surface view in branches, cystocarps arising on short axillary branches and tetrasporangia borne in stichidia. ...
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... However, in Griffithsia corallinoides, Chemin (1928) observed that thalli shed branchlets even in calm waters. Polysiphonia propagulifera and Chondria bulbosa are described as deep-water species living down to 36 m depth (Womersley 1979;Gordon-Mills & Womersley 1987). At such depths, thalli are unlikely to be subject to the effects of waves, and the falling of multicellular propagules must be spontaneous or due to other mechanical causes (e.g. ...
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... Like most of the asexual propagules of algae (Feldmann 1977), they are characterised by the presence of protuberances that facilitate the attachment to the substratum. Moreover, they contain floridean starch granules, as reported for other vegetative propagules (Okamura 1902, Gordon-Mills and Womersley 1987, Maggs and Hommersand 1993 and this suggests that they could also be over-wintering organs, as observed in Acanthophora nayadiformis (Cecere and Perrone 2002) and Alsidium corallinum C. Agardh . Since in the genus Hypnea stellate propagules occur in only two species, H. cornuta and H. stellulifera (J. ...
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Laurencia Lamouroux (Rhodophyta) was recently separated into three genera–Laurencia, Chondrophycus (Tokida et Saito) Garbary et Harper and Osmundea Stackhouse – each of which was newly defined based on vegetative and reproductive structures. In this study, the previously unknown vegetative and reproductive morphology of two Australian endemic species of Laurencia, L. clavata Sonder and L. elata (C. Agardh) Harvey, was studied, particularly in the context of the revised generic delineation. These species exhibit vegetative axes with four pericentral cells and trichoblast-type spermatangial development. Tetrasporangia are abaxially produced from the existing third and fourth pericentral cells. L. clavata has terete thalli with distinctive verticillate branching and is similar to Chondria C. Agardh, rather than to Laurencia, in having an unusually marked constriction at the base of the branches and starch accumulation in subcortical and medullary cells. Compared to Laurencia, apical cells of this species exhibit a less oblique division ; the resulting recognizable axial cell rows extend somewhat below the branches, and particularly at a young stage they are also clear throughout branchlets. However, other vegetative and spermatangial structures show that L. clavata is more closely allied to Laurencia than to Chondria, and it is placed in Laurencia. By contrast, L. elata exhibits morphology typical of Laurencia and is characterized by large, robust, compressed thalli with fastigiately distichous branching and an extensive secondary cortex. Furthermore, it appears to be distinct from similar species in sometimes having a parasitic species of Janczewskia Solms-Laubach (Rhodophyta). Taxonomy of Laurencia is discussed on the basis of these and previous studies.
Article
A morphological, anatomical, and molecular study of the two genera (Heterocladia and Trigenea) and three species of the tribe Heterocladieae (Rhodomelaceae, Ceramiales) is presented. First collections of male and female gametophytes of Heterocladia australis Decaisne and Trigenea umbellata J. Agardh and of tetrasporophytes of the type species of Trigenea, T. australis Sonder, have allowed a much clearer assessment of these taxa from a classical morphological standpoint. Reproductive and vegetative characters of the two Trigenea species are shown to be virtually identical to those of Heterocladia, which differs from Trigenea principally in having both flattened and terete lateral branches, as opposed to exclusively terete axes throughout. As a consequence, we propose to transfer the Trigenea species to the earlier-named genus Heterocladia as H. caudata L. Phillips, H.-G. Choi, G.W. Saunders et Kraft, nom. nov. and H. umbellata ( J. Agardh) L. Phillips, H.-G. Choi, G.W. Saunders et Kraft, comb. nov. The close relationship of the three species is supported by molecular data, as nucleotide sequences of the 18S rRNA gene from each are nearly identical. The same sequences from species of eight other rhodomelaceous genera plus those from five outgroup taxa are analyzed to provide grounds for preliminary phylogenetic inferences about the position of the Heterocladieae in the Rhodomelaceae. Both the Heterocladieae and the Rhodomelaceae are monophyletic taxa in our analyses, the Heterocladieae grouping weakly with the Bostrychieae and the problematic Australian endemic genus Sonderella, the latter yet to be assigned to a tribe. Representatives of groups with which Heterocladia has been associated previously, such as the Lophothalieae and Brongniartelleae, appear to be only distantly related, although many more taxa need to be analyzed before the systematic position of the genus becomes clear.
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A.1.K. MILLAR. 2000. Spirophycus acicularis, a new red algal genus and species in the Lophothalieae (Rhodomelaceae, Ceramiales) from eastern Australia. Phycologia 39: 87-95. Spirophycus acicularis A. Millar gen. et sp. nov. (Lophothalieae, Rhodomelaceae, Ceramiales, Rhodophyta) is a monotypic genus described from sublittoral habitats in the Solitary Islands Marine Park (29°47'S, l53 °l8'E), on the northern New South Wales coast of eastern Australia, near Coffs Harbour. Plants grow on the stalks of polychaete tube worms and consist of erect, subdichotomous, polysiphonous axes bearing a variable number of five to ten periaxial cells. Numerous pigmented, determinate, unbranched, monosiphonous trichoblasts are produced exogenously in a spiral sequence and bear the repro­ ductive structures. Indeterminate laterals also arise exogenously in a similar manner to the trichoblasts. Spermatangial branches form compact clusters or heads around the apices of indeterminate, dwarf laterals but themselves lack sterile laterals. Tetrasporangia are borne in stichidia, which are modifications of trichoblasts, are produced one per segment, and are spirally arranged within the stichidia. Supporting cells of the carpogonial branches cut off only one sterile cell group. Plants show a superficial resemblance to Spirocladia barodensis and Lophocladia kuetzingii, but differ from these mostly by the unbranched nature of their trichoblasts and by the variable number of their periaxial cells. Spirophycus is considered to belong to the tribe Lophothalieae (even though the variable number of periaxial cells is alien to that tribe) and a dichotomous key to the included genera is offered. The variable number of periaxial cells is a feature which is shared with at least one genus (Schizochlaenion) of the tribe Brongniartelleae, and critical comparisions between these two tribes are made.
Article
As part of an ongoing project to substantially increase knowledge of the marine algal flora of the French Pacific territory of New Caledonia, a survey of the Nouméa region was conducted that has resulted in the discovery of 41 previously unrecorded species of macroalgae, including 1 Chlorophyta, 1 Phaeophyceae (Heterokontophyta) and 39 Rhodophyta. Among the biogeographically interesting new records are the green macroalga Rhipilia penicilloides N’Yeurt et Keats (previously endemic to the islands of Fiji some 1000 km east of new Caledonia) and the brown alga Cutleria mollis Allender et Kraft (originally described from Lord Howe Island some 1000 km to the south). The red alga Gloiophloea articulata Weber-van Bosse, known only from its initial discovery in 1928 from the Mascarene Islands in the western Indian Ocean, is now recorded in the deep-water channels of the Nouméa region of New Caledonia. The widely distributed Indian Ocean species Corynomorpha prismatica (J. Agardh) J. Agardh has its easternmost distribution record from this area, and Dotyella hawaiiensis (Doty et Wainwright) Womersley et Shepley is recorded for the first time outside its central-Pacific distribution. These new discoveries represent a 12% increase in the total number of species (377) that are reliably known from New Caledonia.
Article
Much of the marine algal material collected during Perry's Japan Expedition of 1852–54 and Rodgers’ North Pacific Exploring Expedition of 1853–56 was sent by Asa Gray of Harvard University to William Henry Harvey (1811–66) of Trinity College, Dublin, for examination. Preliminary accounts were published in 1857 and 1860, but the full descriptions and illustrations intended were never completed for publication. Original specimens collected from Japan during these expeditions are deposited in the Herbarium of Trinity College, University of Dublin, and in the Natural History Museum, London. The red algae are re-examined and, where necessary, lectotypes are designated. The transfer of Polysiphonia stimpsonii Harvey to Enelittosiphonia is proposed as Enelittosiphonia stimpsonii (Harvey) Kudo et Masuda in Masuda et al. comb. nov. It is concluded that Polysiphonia flabellulata Harvey, which has in recent years been omitted from the Japanese marine algal flora, is an independent, characteristic species with six periaxial cells. Caulacanthus compressus Harvey is reduced to be synonymous with Gloiopeltis complanata (Harvey) Yamada, and Wrangelia tayloriana Tseng is synonymized with Wrangelia tanegana Harvey.
Article
Twenty-four species of marine macroalgae are recorded from the mainland coast of New South Wales for the first time. One species, Laurencia platyclada Boergesen, represents a new record for Australia and the Pacific Ocean. Included in these new records is the introduced, invasive and cold-tolerant strain of the green alga Caulerpa taxifolia, which was formerly known only as native, non-invasive populations from Lord Howe Island. Based on published accounts, the composition of the marine benthic algae for the state of New South Wales now stands at 131 green, 140 brown and 449 red macroalgae. This baseline information adds significantly to our knowledge of the overall marine biodiversity of the state, as well as to the phycogeography of the southwestern Pacific region.
Chapter
Laurencia succulenta sp. nov. (Rhodophyta) is described from Korea. This species exhibits vegetative and reproductive structures typical of the genus, but is distinct from similar species in its epiphytic habitat and the fleshy, robust, thick and subcompressed thalli with basically distichous branching. In addition, it is readily distinguished from the most similar species, such as L. nipponica Yamada and L. okamurae Yamada, by the cystocarps with a somewhat protuberant ostiole. In a phylogenetic analysis of 47 species of the Laurencia Lamouroux complex from various localities around the world based on 49 morphological characters, four major clades (Laurencia, Chondrophycus palisadus (Yamada) Nam group, C. cartilagineus (Yamada) Garbary et Harper group and Osmundea Stackhouse assemblage), each of which forms a monophyletic group, were recognized. Among these, the Laurencia clade is basal to the overall assemblage, and is defined by the vegetative axis with four rather than two pericentral cells. The Osmundea clade is supported by autapomorphic characters for the genus, features associated with spermatangial formation of the filament type and tetrasporangial production from epidermal cells. By contrast, Chondrophycus, a genus characterized by a combination of features (vegetative axis with two pericentral cells, trichoblast-type spermatangial development and tetrasporangial production from pericentral cells), is paraphyletic, and the species were separated into two well-supported clades, the C. palisadus group and C. cartilagineus group. These clades are distinguished from each other by the position of the first pericentral cell relative to the trichoblast, the presence or absence of fertility at the second pericentral cells and number of sterile pericentral cells in the tetrasporangial axis, the pattern of formation of spermatangial branches on trichoblasts, post-fertilization feature associated with the formation time of the auxiliary cell, and, probably, the number of pericentral cells in the procarp-bearing segment. Of these features, the side position of the first pericentral cell in the latter group (a synapomorphy for the C. cartilagineus group plus Osmundea) suggests that the C. cartilagineus group is more closely related to Osmundea than to the C. palisadus group. This cladistic analysis indicates that Chondrophycus is not monophyletic, suggesting that the C. palisadus group should be separated from Chondrophycus at the genus level. Based on this result, Palisada (Yamada) stat. nov. is proposed for the group, together with an emendation of the generic delineation of Chondrophycus, and relevant nomenclatural changes for several Chondrophycus species are also included. In addition, Corynecladia J. Agardh is reinstated for the type species L. clavata Sonder.
Article
The monotypic genus Husseyella Papenfuss [type species, H. australis (J. Ag.) Papenfuss (=H. rubra (Harvey) comb. nov.)] is distinguished from other genera in the tribe Chondrieae (Rhodomelaceae) by the production of reproductive structures (male unknown) in short branchlets (2–3 mm long) which occur in clusters of up to 10 in the axils of the branches. The procarps appear to be formed subterminally on these short branchlets, and subsequently there may develop 1 or 2 cystocarps per branchlet. Tetrasporangia occur in the cortex of the branchlets. Ruthenium red-positive cell wall thickenings which occur in pericentral cells and subcortical cells in some parts of the thallus are distinctive in form, becoming lobed and very thick in older cells, almost filling the lumen of the cell. The combination of features which are distinctive at the specific level include the tendency towards subpolychotomous branching, the characteristic cross section of median branches showing regular rings of pericentral and subcortical cells separated by rhizoidal growth, and the formation of a secondary cortex in lower parts of older plants. Our knowledge of H. rubra depends on about 13 collections, the most recent of which was in 1954. The monotypic genus Husseyella Papenfuss [type species, H. australis (J. Ag.) Papenfuss (=H. rubra (Harvey) comb. nov.)] is distinguished from other genera in the tribe Chondrieae (Rhodomelaceae) by the production of reproductive structures (male unknown) in short branchlets (2–3 mm long) which occur in clusters of up to 10 in the axils of the branches. The procarps appear to be formed subterminally on these short branchlets, and subsequently there may develop 1 or 2 cystocarps per branchlet. Tetrasporangia occur in the cortex of the branchlets. Ruthenium red-positive cell wall thickenings which occur in pericentral cells and subcortical cells in some parts of the thallus are distinctive in form, becoming lobed and very thick in older cells, almost filling the lumen of the cell. The combination of features which are distinctive at the specific level include the tendency towards subpolychotomous branching, the characteristic cross section of median branches showing regular rings of pericentral and subcortical cells separated by rhizoidal growth, and the formation of a secondary cortex in lower parts of older plants. Our knowledge of H. rubra depends on about 13 collections, the most recent of which was in 1954.
Article
Twenty-six species of Polysiphonia are recognized from the coast of southern Australia. Their relationships are discussed, their distribution outlined and ecological notes are given. Characters found to be satisfactory for species delimitation include the number of pericentral cells. presence or absence and degree of cortication, whether or not rhizoids are cut off from the parent pericentral cells, the origin of lateral branches near apices (whether from the basal cell of trichoblasts or independent of them), the habit of the thallus, and dimensions and proportions of the thallus and segments of the branches. The presence and frequency of trichoblasts (or scar cells) may be characteristic but can vary with activity of growth of the thallus in some species. Cystocarps offer few characters, though the degree of enlargement of the ostiolar cells may be useful in some species. In male plants, satisfactory characters are whether the spermatangial branch replaces the whole trichoblast or only one basal furcation, and the presence or not of sterile apical cells. The form of the tetrasporangial branchlets and arrangement of tetrasporangia are often useful. Of the 26 species, 17 belong to subgenus Oligosiphonia and nine to subgenus Polysiphonia. Four species (P. scopulorum, P. subtilissima, P. sertularioides and P. brodiaei) are species of widespread distribution, the last-named possibly spread by shipping. One species (P. pungens) is known from the Pacific Coast of Canada and now from the State of Victoria. Some 17 species appear to be restricted to southern Australia, including I1 species newly described (P. haplodasyae, P. shepherdii, P. brevisegmenta, P. amphibolis, P.perriniae. P.propagulqera, P. australiensis, P. abscissoides, P. teges, P. constricta and P. adamsiae). Two species (P. decipiens, P. isogona) occur in southern Australia, New Zealand, and possibly subantarctic regions, while two others (P. abscissoides, P. adamsiae) occur both in New Zealand and in southern Tasmania. One species (P. haplodasyae) is a very small species apparently confined to its host Haplodasya. It appears that P. mollis has been recorded incorrectly from various other countries, and clearly much more critical study of the species of Polysiphonia is needed, especially of early species described from the Mediterranean and West Indies.