Xanthidium verrucosum M.A.Santos, G.J.P.Ramos & C.W.N.Moura, 2022

Santos, Maria Aparecida Dos, Ramos, Geraldo José Peixoto & Moura, Carlos Wallace Do Nascimento, 2022, Taxonomic notes on genera Bourrellyodesmus and Xanthidium (Zygnematophyceae) from Chapada Diamantina, Bahia, Brazil, Phytotaxa 536 (3), pp. 228-242 : 239-240

publication ID

https://doi.org/ 10.11646/phytotaxa.536.3.3

DOI

https://doi.org/10.5281/zenodo.6333074

persistent identifier

https://treatment.plazi.org/id/5921D53A-FFF1-AC0C-47A8-FC4DFD2FFF0B

treatment provided by

Plazi

scientific name

Xanthidium verrucosum M.A.Santos, G.J.P.Ramos & C.W.N.Moura
status

sp. nov.

Xanthidium verrucosum M.A.Santos, G.J.P.Ramos & C.W.N.Moura sp. nov. ( Figs 7 View FIGURES 7 , 55–65 View FIGURES 48–65 )

Diagnosis:—Cell approximately as long as broad (excluding spines), deeply constricted, sinus narrow, linear. Semicells semicircular, lateral margins convex, decorated with six pairs of upward-facing spines (four arranged at the apical margin and two spines at lateral, near the apical margin of semicells), with mamillate base; sometimes one pair of tiny spines straight in each basal angle; three or four large warts in the semicells center; semicell subcircular in lateral view; elliptic in apical view, with a pair of spines in the angles, and 3–4 warts on each side. Cell wall hyaline, sometimes brownish, punctate, with 3–4 median facial warts. Chloroplast with two pyrenoids per semicell. No zygospores were observed. Cell dimensions: length without spines 55–58 μm, with spines 67–95 μm, width without spines 51–55 μm, with spines 63–95 μm, thickness 42–50 µm, isthmus 33–34 μm, spines 9–25 μm long.

Holotype:—Material numbered ( HUEFS 253753 About HUEFS !) [pro parte], deposited at Herbarium of State University of Feira de Santana, population partially illustrated here ( Figs 7 View FIGURES 7 , 52–62 View FIGURES 48–65 ).

Paratype:—Material numbered ( HUEFS 253766 About HUEFS ) [pro parte], deposited at Herbarium of State University of Feira de Santana .

Type locality:— BRAZIL. Bahia: Andaraí, Marimbus do Baiano, Lagoa do Baiano , Lat. 12°45’52.4”S, Long. 41°18’34.5”W, 09 April 2018, M. A GoogleMaps . Santos , J. T . X. Neto & F. M . Costa s/n ( HUEFS 253753 About HUEFS ) .

Habitat:—The new species was rarely found in the study area, generally associated to periphyton of C. caroliniana and U. foliosa ; EC 0.02 mS. cm-1 (±0.01); DO 7.4 (±1.2); TDS 0.02 (±0.01); pH 8.2 (±0.5); T ° C 30 (±1.4); WT 71.8 (±3.9) cm.

Etymology:—The specific epithet refers to the surface ornamentation composed of warts arranged on the face of the semicells.

Differential diagnosis:—The present taxon differs from other species of the genus Xanthidium by having semicircular semicells with convex lateral margins, decorated with six pairs of upward-facing spines with a mamillate base, and ornated with 3–4 large warts on the face of the semicells in the frontal view.

The newly described species resembles Xanthidium paulense Borge (1918: 42) due to the shape and size of the cell, and the arrangement of the spines. However, the latter species differs in that it has superior angles of semicells decorated with single spines, and each semicell face is decorated with one convergent spine.

Xanthidium verrucosum is similar to Xanthidium cristatum Brébisson ex Ralfs (1848: 115) , but the latter differs by having 10 marginal spines per semicell (four pairs and two singles at the base on each side), one or two warts in the semicell center (sometimes strongly reduced or even lacking), and relatively small cell size (40 x 35 μm without spines) ( Šťastný et al. 2013).

In the study area, we observed some morphological variations in the specimens: warts can be 3–4 per semicell; the spines (12) per semicell may be shorter (9–16 μm) or longer (23–25 μm), and some individuals may have an additional pair of tiny spines (2–5 μm), one at each basal angle.

Despite the polymorphism observed, X. verrucosum presents a distinct morphological pattern, which is different from any other known species of the genus Xanthidium .

M

Botanische Staatssammlung München

A

Harvard University - Arnold Arboretum

J

University of the Witwatersrand

T

Tavera, Department of Geology and Geophysics

F

Field Museum of Natural History, Botany Department

DO

Société d'Agriculture Sciences et Arts

C

University of Copenhagen

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