Leptophytum W.H.Adey, 1966

Holotype species: Leptophytum laeve W.H.Adey

Original publication and holotype designation: Adey, W.H. (1966). The genera Lithothamnium, Leptophytum (nov. gen.) and Phymatolithon in the Gulf of Maine. Hydrobiologia 28: 321-370, 112 figs, tables I-VI.

Description: Non-geniculate, thin, crust strongly adhering to pebbles and shells, growing with entire thallus attached; thallus surface smooth except for raised conceptacles; multi-filament hypothallium sub-parallel to substrate, mostly arching up to form perithallium, some filaments arching downward, dead-ending on substrate; epithallium absent or of very few (1-3), thin-walled, non-photosynthetic cells; meristem small-celled, intercalary below epithallium; elongation of perithallial cells gradual during burial; double mode of calcification absent; bi/tetrasporangial conceptacles multiporate; male conceptacles with mature spermatangial systems simple, composed of lunate spermatangial mother cells on the floor; spermatangial mother cells cutting off up to 5 spermatangia, dendroid spermatangial mother cells rare; female (uniporate) conceptacles conical; carposporangia produced peripherally around central fertile zone that remains more or less flat; older conceptacles not becoming buried in thallus, but thalli may overgrow one another resulting in conceptacles appearing to be buried.

Information contributed by: Paul W. Gabrielson. The most recent alteration to this page was made on 2024-02-24 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as neuter.

Most recent taxonomic treatment adopted: Athanasiadis, A. & Ballantine, D.L. (2024). Anatomy and classification of the Mesophyllaceae (Corallinales, Rhodophyta), based on phylogenetic principles. Smithsonian Contributions to Botany 118: [i]-xii, [1]-216, 83 figures, 6 tables.

Comments: There are two problems with Leptophytum, the genus created by Adey (1966). The first is that the basionym of the generitype species, Leptophytum laeve, is Lithophyllum laeve Strömfelt (1886), a later homonym of Lithophyllum laeve Kützing 1847, and therefore an illegitimate name. A solution to this problem was recommended by the late, Dr. Paul C. Silva, who proposed that Leptophytum laeve be treated as a new name (Düwel & Wegeberg, 1996, p. 473, cited as P. C. Silva personal communication), a solution that AlgaeBase and Adey et al. (2015) have adopted. The type of the species and genus remains Strömfelt's type material of Lithophyllum laeve.
The second problem is that the holotype is represented by only a single microscope slide that some consider unambiguously to be Leptophytum laeve (Adey et al. 2001) whereas others (Düwel and Wegeberg 1996, Woelkerling et al. 2002) believed that it is "...demonstrably ambiguous and cannot be critically identified for purposes of the precise application of the name to a taxon" (McNeill et al. 2012, Article 9.8). Düwel and Wegeberg (1996) proposed an epitype based on material collected from the type locality (topotype material) that upon examination they believed to represent Phymatolithon lenormandii (Areschoug) W.H. Adey, making Leptophytum a synonym of Phymatolithon. Adey et al. (2015) are convinced that Strömfelt's holotype microscope slide is L. laeve based on the non-overlapping pore plate diameters of asexual conceptacles and on the non-overlapping sporangial lengths, both 1.5-2 times larger in L. laeve compared to P. lenormandii, and distinct from all other Subarctic non-geniculate corallines. Both Adey (1966) and Düwel and Wegeberg (1996) were unable to find material at the type locality, and, additionally, L. laeve does not occur intertidally, where Strömfelt's material was said to have been collected. The locality of the type collection may be incorrect or the type material was cast ashore and into a tide pool during the heavy storms that frequent the south coast of Iceland. DNA sequences, using three markers from three specimens (US 169242, US 170538 and US 170934) that were identified by Adey as Leptophytum laeve belong to a genus distinct from both Phymatolithon and Clathromorphum. As the holotype specimen (one microscope slide) has features that agree with the sequenced specimens and that differ from all other Subarctic nongeniculate corallines and the DNA sequences also are distinct from all other Subarctic nongeniculate corallines, Adey et al. (2015) proposed recognition of Leptophytum as a distinct genus and regarded the Düwel and Wegeberg (1996) epitypification as unnecessary.

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Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=32972

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 24 February 2024. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 April 2024

 
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