| 1. |
- Athanasiadis, Athanasios
(författare)
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A study of the original material of Lithothamnion engelhartii Foslie (Corallinales, Rhodophyta)
- 2017
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 60:1, s. 67-78
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Tidskriftsartikel (refereegranskat)abstract
- Eight collections of the type material of Lithothamnion engelhartii from Cape Jaffa and Kingston (South Australia) were re-examined and two disparate entities were shown to be included. Some specimens exhibit embedded conceptacles in the thallus where the perithallium dominates. The other specimens lack embedded conceptacles and the thallus is formed by unattached-superimposed lamellae where the hypothallium prevails. The lectotype selected here fits the second description and is in agreement with most other type specimens and recent material collected at Eyre Peninsula (South Australia). The lectotype specimen displays dorsiventral organization lacking perithallial protuberances. The hypothallium is polystromatic with coaxial to non-coaxial regions and forms a relatively thin ascending perithallium. Subepithallial cells are elongate and support single flattened epithallial cells. Multiporate conceptacles are bisporangial, develop in dense aggregations, and do not become embedded in the thallus (except via superimposition of new lamellae). Pore canals are conical to pyriform and develop differentiated cells lining the canals along the base. Syntype material exhibits simple spermatangia, and this character, together with the presence of elongate basal pore cells and the lack of a predominantly coaxial hypothallium, suggests an affiliation with the temperate species of Leptophytum from the NE Pacific.
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| 2. |
- Athanasiadis, Athanasios
(författare)
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A study of the type material of Lithophyllum hibernicum (Lithophyllaceae, Corallinales, Rhodophyta) with comments on L. bathyporum and L. incrustans
- 2020
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 16:1, s. 68-76
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Tidskriftsartikel (refereegranskat)abstract
- The original material of Lithophyllum hibernicum Foslie was re-examined and two different species, unequally represented in the collection were found: most thalli belong to a sterile species of Lithophyllum, represented in the protologue by elements related to cell size and coaxial arrangement. A few sterile thalli belong to Lithothamnion cf. corallioides, and this species is also represented in the protologue by a single statement of branch size. Yet, the species of Lithophyllum is the sole representative in Foslie's unpublished materials included in the type collection in TRH. A previous lectotypification, contradicting Art. 9.14 (that demands the type to correspond to its original description rather than to a certain taxonomic concept), is sustained because it preserves Foslie's intent. The lectotype of L. hibernicum is a sterile, branched rhodolith with characteristic cup- or funnel-shaped formations on its thallus. Syntypes are inhabited by an endo-, epiphytic species of Gelidiales forming openings resembling conceptacle ostioles. Molecular comparison with topotypes is needed before synonymy with the common epilithic species Lithophyllum bathyporum in the NE Atlantic should be accepted.
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| 3. |
- Athanasiadis, Athanasios
(författare)
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Amphithallia, a genus with four-celled carpogonial branches and connecting filaments in the Corallinales (Rhodophyta)
- 2019
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The South African marine alga Amphithallia crassiuscula, previously subsumed in the widely reported Synarthrophyton patena, is here re-described as a distinct species and genus. Thalli grow as obligate epiphytes on Gelidium capense in the upper sublittoral zone (while S. patena grows on Ballia callitricha). Gametophytes are monoecious with four-celled carpogonial branches and sterile cells are borne on supporting cells (dioecious or hermaphroditic with two or three-celled carpogonial branches and sterile cells borne on hypogynous cells in Synarthrophyton). Postfertilization stages involve a connecting filament linking the carpogonium to several putative auxiliary cells, demonstrating a non-procarpic condition with apparent absence of a fusion cell. Gonimoblast filaments develop at the level of basal cells of carpogonial branches. Spermatangial mother cells remain either unbranched (cutting off spermatangia only) or develop dendroid (branched) filaments with terminal spermatangia (as in Synarthrophyton). Multiporate conceptacles develop straight pore canals lined by non-differentiated cells (conical canals with differentiated pore cells along the base in Synarthrophyton). The here described pre- and post-fertilization characters are new for the order Corallinales motivating the establishment of the new genus Amphithallia. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.
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| 4. |
- Athanasiadis, Athanasios
(författare)
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Canal differentiation in multiporate conceptacles of Mesophyllaceae (Corallinales, Rhodophyta), with recognition of Thallis gen. nov. from South Africa, and Perithallis gen. nov., Printziana gen. nov. and Sunesonia gen. nov. from southern Australia-New Zealand-Chatham
- 2021
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 17:9-10, s. 904-45
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Tidskriftsartikel (refereegranskat)abstract
- The structure of canals in multiporate conceptacles of Mesophyllaceae is analysed and several distinct types are recognized. In what appears to be the plesiomorphic condition, canals are straight and bordered by non-differentiated pore cells. In the majority of Mesophyllaceae, pore cells are thinner-wider, starting from basal cells and extending towards the apical opening. This can be coupled with development of triangular (conical) or pyriform canals. Other modifications occur at species or genus level, or across several genera, the most distinctive being formation of cell bars (Phragmope discrepans), elongate basal cells (Melyvonnea), or branched pore filaments composed of fewer cells than adjacent roof filaments and provided with elongate subbasal (or basal and subbasal) cells (Thallis-Perithallis, respectively Printziana-Sunesonia). In Thallis-Perithallis-Sunesonia-Melyvonnea, pore filaments are composed of fewer cells than adjacent roof filaments and terminate below the roof surface. It is postulated that the elongate basal cells in Melyvonnea resulted after loss of basally branched pore cells, an evolutionary step that finds justification in the new genus Sunesonia where homologous cells become reduced or deteriorated. A new thallus organization (aniso-bilateral) characterized by a diminutive ventral perithallium distinguishes Perithallis. Nine new taxa are described, including accounts of their historical record, typifications, comparison of their types to new collections, and the published molecular work that provides further support: Thallis capensis gen. & sp. nov., Perithallis incisa gen. et comb. nov., P. chathamensis (Foslie) nov. comb., Printziana australis gen. & nom. nov. and Sunesonia pseuderubescens gen. et sp. nov.
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| 5. |
- Athanasiadis, Athanasios
(författare)
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Capensia fucorum (Esper) gen. et comb. nov (Mesophyllaceae, Corallinales, Rhodophyta), a hemiparasite on Gelidium from South Africa
- 2017
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 60:5, s. 555-565
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Tidskriftsartikel (refereegranskat)abstract
- Capensia fucorum (= Mesophyllum capense) is described as the first hemiparasitic coralline genus and species infecting a non-coralline host (species of Gelidium). Amongst coralline algae, Capensia also exhibits a unique thallus organisation displaying sympodial branching at the margin and a monostromatic hypothallium with gradually ascending and descending filaments in the main thallus. Sympodial branching occurs from the ventral side of hypothallial cells and guarantees close adhesion to the host, while older hypothallial filaments are displaced dorsally to form the perithallium. Haustoria develop as terminal cells of descending filaments and penetrate the first and occasionally second cortical layer of the host. Capensia is monotypic with restricted distribution on Gelidium capense and Gelidium pteridifolium from South Africa. The generitype Capensia fucorum (= Millepora fucorum Esper) is originally described from the Cape of Good Hope. The new hemiparasitic genus, like its synonym, belongs to Mesophyllaceae and its closer relationship remains to be identified, starting the search in members of this family co-occurring with Capensia in South Africa.
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| 6. |
- Athanasiadis, Athanasios
(författare)
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Carlskottsbergia antarctica (Hooker fil. & harv.) gen. & comb. nov., with a re-assessment of synarthrophyton (mesophyllaceae, corallinales, rhodophyta)
- 2019
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Ingår i: Nova Hedwigia: Zeitschrift für Kryptogamenkunde. - : Schweizerbart. - 0029-5035. ; 108:3-4
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Tidskriftsartikel (refereegranskat)abstract
- - Carlskottsbergia antarctica gen. & comb.nov., considered to be a distinct species for more than a century and more recently subsumed in the broad concept of Synarthrophyton patena, is segregated possessing monostromatic hypothallium (polystromatic in Synarthrophyton), and tetrasporophytes with straight to pyriform canals (larger conical canals in Synarthrophyton). Male conceptacles develop lunate, unbranched spermatangial mother cells (SMCs) on the floor, the walls and the roof (either unbranched, or branched-dendroid SMCs, or hermaphroditic in Synarthrophyton). Carpogonial branches are two-or three-celled and post-fertilization stages involve a fusion cell that incorporates at least one hypogynous and neighboring supporting cells, leaving adjacent hypogynous cells intact. Gonimoblast filaments radiate incorporating the cytoplasm of peripheral hypogynous cells and cut off carposporangia from the periphery of the fertile zone that occurs on a flattened chamber floor (as in Synarthrophyton). Carlskottsbergia antarctica is widely distributed, including localities in southern Chile and southern Argentine, the Falklands, and co-occurring with S. patena in New Zealand and the Aucklands. The circumscription of Synarthrophyton is restricted to include the generitype S. patena from New Zealand and the Aucklands, and species from southern Australia (the latter differing in developing branched-dendroid SMCs and a larger thallus). © 2018 J. Cramer in Gebrüder Borntraeger Verlagsbuchhandlung, Stuttgart, Germany.
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| 7. |
- Athanasiadis, Athanasios
(författare)
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Grønlands havalger
- 2012
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 55:1, s. 113-115
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- “Grønlands Havalger” was the title of Rosenvinge’s (1893) first contribution on the seaweeds of Greenland; the work was reviewed by Batters (1894) in Grevillea. ...
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| 8. |
- Athanasiadis, Athanasios, et al.
(författare)
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Hydrolithon abyssophila sp. nov. (Hydrolithoideae, Corallinales), a bisporic coralline from the insular shelf edge of Puerto Rico and the Virgin Islands (US)
- 2013
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Ingår i: Botanica Marina. - 0006-8055 .- 1437-4323. ; 56:5/6, s. 495-505
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Tidskriftsartikel (refereegranskat)abstract
- A new species of Hydrolithon is described from mesophotic habitats, between 30 and at least 76 m depth, off La Parguera, Puerto Rico, and St Thomas, Virgin Islands (Caribbean Sea). Its encrusting thallus covers corals and rocks. Hydrolithon abyssophila sp. nov. is distinctive in developing bisporangia that are about twice as large as its congeners and in lacking both perithallial protuberances and trichocytes in horizontal or vertical groups. It reproduces primarily by uninucleate bispores that presumably recycle the parental phase. Unfertilized carpogonia were observed in one collection suggesting the rare occurrence of gametophytic reproduction in the species.
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| 9. |
- Athanasiadis, Athanasios
(författare)
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Leptophytum flavescens comb. nov. (Corallinales, Rhodophyta), an Arctic endemic from the sublittoral of NW Spitsbergen, North Norway, and western Novaya Zemlya, with epitypification of L. laeve
- 2016
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 12:5, s. 551-558
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Tidskriftsartikel (refereegranskat)abstract
- Type material of Lithothamnion flavescens Kjellman, originally described from Karlsøy (Troms) and Karmakul Bay (Novaya Zemlya), is re-examined and a lectotype is selected. Type specimens and other collections from NW Spitsbergen and North Norway possess distinctive characters of the genus Leptophytum, including the development of flattened epithallial cells, short subepithallial cells, and simple spermatangial structures. Leptophytum flavescens (Kjellman) comb. nov. resembles the generitype Leptophytum laeve, differing in having: (1) a thicker perithallium, to 900µm (vs. 350µm in L. laeve), that embeds older conceptacles, and (2) non-differentiated (in size or shape) pore cells of multiporate roofs. An epitype for L. laeve is also selected, which consolidates the status of this species and the genus, in agreement with the current literature and all publications prior to 1996.
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| 10. |
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