Pseudoderbesia eckloniae Huisman & Verbruggen, 2020

Huisman, John M. & Verbruggen, Heroen, 2020, Pseudoderbesia eckloniae, sp. nov. (Bryopsidaceae, Ulvophyceae) from Western Australia, Cryptogamie, Algologie 20 (3), pp. 19-23 : 20

Pseudoderbesia eckloniae Huisman & Verbruggen , sp. nov.

( Fig. 1 )

HOLOTYPE. — PERTH 09134638 . Collected at Cape Peron, Western Australia (32°16.18’S, 115°41.178’E), epiphytic on Eckloniaradiata at 2 m depth, 9.I.2019, J. M.Huisman 9.1.19.1A-C (three specimens mounted on sheet) ( Fig. 1B ).

PARATYPE. — PERTH 09134646 . Loc. id., 30.XII.2018 , J. M.Huisman 30.12.18.

ETYMOLOGY. — The epithet “eckloniae ” refers to the species’ only known host, Ecklonia radiata .

DESCRIPTION

Thallus grass green, forming a velvety layer on the surface of degrading branches of Ecklonia radiata ( Fig. 1A ), spreading laterally for up to 10 cm, siphonous, with dichotomously branched upright axes arising from a stoloniferous base ( Fig. 1C ). Stolons terete, 35-50 µm in diameter, attached by elongate, terete rhizoidal siphons. Upright axes dichotomously (rarely trichotomously) branched 4-7 times when mature, dichotomies mostly at similar levels but occasionally unequal, with slight constrictions commonly present at branch bases ( Fig. 1D ). Upright axes proximally 50 µm in diameter when young, 120-200 µm in diameter when mature; distal branches markedly narrowing, with ultimate branches 12-25 µm in diameter. Chloroplasts numerous, elongate to ovate, each with a single pyrenoid ( Fig. 1E ). Reproduction not observed.

MOLECULAR ANALYSIS

The rbc L gene of four samples of the new species was sequenced following the procedures of Verbruggen et al. (2009) and submitted to GenBank (MT108929). The four sequences of Pseudoderbesia eckloniae , sp. nov., were identical and only one was included for further analysis. The sequence was aligned with those of Bryopsidineae used in Leliaert et al. (2014) and Lambia antarctica (Skottsberg) Delépine ( Cremen et al. 2019) . A maximum likelihood phylogenetic tree was inferred with RAxML 8.2.10, using a GTR+G+I model and 100 standard bootstraps ( Stamatakis 2014). The phylogenetic tree ( Fig. 2 ) shows that the genus Pseudoderbesia is related to Lambia Delépine and Bryopsis J.V.Lamouroux , but the exact relationships among these genera is not recovered with sufficient bootstrap support. The divergence between Pseudoderbesia eckloniae , sp. nov., and Pseudoderbesia sp. from Greece is clear in the tree, and the rbc L interspecific divergence between these two Pseudoderbesia species is 3.87%.

Figures

FIG. 1. — Pseudoderbesia eckloniae Huisman & Verbruggen, sp. nov.: A, specimen from the type collection growing on Ecklonia radiata (C.Agardh) J.Agardh at Cape Peron, Western Australia; B, one of three specimens from the holotype sheet (PERTH 09134638); C, closer view, showing stolons (arrow) and dichotomously branched upright axes;D, detail of upper branches, with slight constrictions at dichotomies.A trichotomy is also present (arrow); E, siphon detail showing elongate chloroplasts, each with a single pyrenoid. Scale bars: A, B, 1 cm; C, 500 µm; D, 100 µm; E, 25 µm.

FIG. 2. — Maximum likelihood phylogenetic tree of the rbcL gene showing the new species Pseudoderbesia eckloniae Huisman & Verbruggen,sp. nov., clustering with the Greek Pseudoderbesia strain. The scale bar is in estimated substitutions per site. Branch labels indicate bootstrap support, shown only when>70.