Dasya sylviae C. W. Schneid., M. M. Cassidy & G. W. Saunders 2021, sp. nov.
Creators: name: Schneider, Craig W.
name: Cassidy, Margaret M.
name: Saunders, Gary W.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Rhodophyta
Florideophyceae
Ceramiales
Dasyaceae
Dasya
Dasya sylviae

description: Dasya sylviae C.W.Schneid., M.M.Cassidy & G.W.Saunders sp. nov.
Fig. 2
Diagnosis
Differing from most species of Dasya by its pronounced pseudodichotomous branching pattern (Fig. 2A– C), and from its most similar congener in habit, D. crouaniana J.Agardh, by its longer pseudolaterals, narrower and shorter tetrasporangial stichidia and axes fully covered with pseudolaterals to barely denuded proximal axes. The new taxon differs from all species of Dasya by its lack of post-sporangial cover cells.
Etymology
The species is named after Dr Sylvia A. Earle, pioneering phycologist, scientist and open-water diver, 50 years after she led the first all-female team of aquanauts in Tektite II on the floor of the Caribbean Sea (Earle 1972 a, 1972b).
Material examined
Type
BERMUDA • Spittal, south of Cooper’s I. off Castle Harbour; 31°19.23333′ N, 64°39.53333′ W; depth 63.8 m; on rhodoliths; 11 Aug. 2016; Schneider & Popolizio 16-21-14; GenBank nos: MW698721 (holotype), MW699769 (isotype); holotype (Fig. 2A): MICH [BDA2031]; isotypes (Fig. 2B–C): Bermuda Natural History Museum, MICH, NY, UNB, US, Herb. CWS [BDA2030].
Additional material
BERMUDA • Ledge north northeast of St. George’s I.; 32°28.79600′ N, 64°35.68833′ W; depth 90 m; 28 Jul. 2016; Schneider & Popolizio 16-11-1, ⊕ [BDA1969] • loc. cit.; depth 60 m; 28 Jul. 2016; Schneider & Popolizio 16-11-10 [BDA1982] • loc. cit.; 32°28.96200′ N, 64°35.25183′ W; depth 90 m; 29 Jul. 2016, Schneider & Popolizio 16-12-2 [BDA1992] • Spittal, offshore of Midocean Point; 32°19.20000′ N, 64°39.48333′ W; depth 62.7 m; 3 Aug. 2016; Schneider & Popolizio 16-17-2 [BDA2011].
Description
Plants epilithic, erect to 17 cm tall, carmine red, arising from small discoidal holdfasts; indeterminate axes sympodially branched, appearing pseudodichotomously branched throughout, only slightly tapering from base to apex (Fig. 2A–C), 0.3–0.8 mm diam. in median to lower portions and completely corticated by rhizoidal downgrowth (Fig. 2D); indeterminate axes densely covered throughout with determinate, lightly pigmented, monosiphonous dichotomously branched axes (pseudolaterals; Fig. 2E), except in some older plants in the most basal portions; pseudolaterals 1.7–5.5 mm in length, 25–91 cells from base to apex, irregularly dichotomously branched from the first to the seventh cell of the pseudolateral, upper portions unbranched and slightly tapering (Fig. 2E); basal cells of pseudolaterals initially globose to ellipsoid (Fig. 2D), 21–37 µm diam. and 12–30 µm long, then slightly elongating; suprabasal cells 19–32 µm diam. and 8–32 µm long, elongating more centrally, 9–22 um diam. and 27–102 µm long, and reaching greatest lengths distally, 8–19 µm diam. and 32–127 µm long; tetrasporangial stichidia single, borne terminally on 3–7-celled unbranched pseudolaterals (Fig. 2F) or terminating basal dichotomies of pseudolaterals (Fig. 2G), lanceolate to narrowly elliptical in outline (Fig. 2F–G), 73–80 µm diam. and 269–305 µm in length at maturity, composed of 10–12 fertile segments, acropetally producing then releasing sporangia (Fig. 2F–G); sporangia globose, 21–29 µm diam., tetrahedrally divided, 3–5 per fertile segment, sporangia borne on 2-celled whorled branches, post-sporangial cover cells lacking (Fig. 2F); one to two spermatangial stichidia terminating a basal dichotomy on 4–10-celled pedicels (pseudolaterals), narrowly elliptical to lanceolate in outline (Fig. 2H), 46–69 µm diam. and 192–258 µm in length at maturity; carpogonial branches and cystocarps unknown.
Distribution and habitat
At present, endemic to mesophotic reefs off Bermuda, western Atlantic Ocean.
description: Published as part of Schneider, Craig W., Cassidy, Margaret M. & Saunders, Gary W., 2021, The pseudodichotomous Dasya sylviae sp. nov. (Delesseriaceae, Ceramiales) from 60 - 90 m mesophotic reefs off Bermuda, pp. 24-37 in European Journal of Taxonomy 751 on pages 28-32, DOI: 10.5852/ejt.2021.751.1377, http://zenodo.org/record/4818423