Bourrellyodesmus comperei M.A.Santos & 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 : 229-231

Bourrellyodesmus comperei M.A.Santos & C.W.N.Moura sp. nov. ( Figs 1 , 8–16 )

Diagnosis:—Cells 1.1 to 1.3 times broader than longer without spines, with a deep, acute-angled open sinus. Semicells trapeziform to subtrapeziform, apical margins are straight and then suddenly curve downward, basal margin ranges from convex to straight, angles with 1 short, solid, convergent, acute spine; circular in lateral view, with 1 median intumescence on each side; elliptic in apical view, sides parallel, angles acute rounded with 1 short spine, 1 tiny granule intramarginal on each side, near the spine, and 1 median intumescence, diagonal-opposite. Cell wall hyaline, smooth, 1 median facial intumescence, and a pair of tiny intramarginal granules. Chloroplast axial 1 per semicell, with 1 pyrenoid. No zygospores were observed. Cell dimensions: length 10–12.5 µm, width without spines 12.5–15 µm, with spines15–17 µm, thickness 7–9 µm, isthmus 4–6 µm, spines 1–1,2 μm long.

Holotype:—Material numbered ( HUEFS 253766 !) [pro parte], deposited at Herbarium of State University of Feira de Santana, population partially illustrated here ( Figs 1 , 8–16 ).

Paratype:—Material numbered ( HUEFS 253775 ) [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, 12 June 2018, M. A. Santos , J. T.X. Neto & F. M. Costa s/n ( HUEFS 253766 ) .

Habitat:—The new species was rarely found in the study area, occurring generally associated to periphyton of Utricularia foliosa , Cabomba caroliniana , and Nymphaea amazonum ; EC 0.0–0.1 mS. cm-1; DO 6.0 (±0.5); TDS 0.02(± 0.01); pH 7.4 (±1); T 28.7 ° C (±1.3); WT 65.5 cm (±4.8).

Etymology:—The epithet is given in honor of Belgian Phycologist Dr. Pierre Compère (1934–2016), author of the genus Bourrellyodesmus , for his contribution to the knowledge of desmids.

Differential diagnosis:— Bourrellyodesmus comperei differs from other species of the genus by having elliptical cells in apical view, parallel sides, acute-rounded angles with 1 short spine, 1 tiny intramarginal granule on each side, near the spine, and 1 median intumescence in each semicell, with a diagonal-opposite arrangement.

Morphologically, B. comperei has a cell shape similar to that of B. sumatranus C.E.M. Bicudo & Compère (1978: 419) , a rare species, described in Indonesia, South of Palembang, Kaju-Agung, South Sumatra. However, the semicells of B. sumatranus are distinct in that they have a convergent facial granule near the isthmus, conical (frontal view), or emarginate (apical view), with no tiny intramarginal granules on apical angles. Compère (1983) characterized specimens of B. sumatranus collected at the Himalayas as having less trapezoidal semicells and the apical angles ornate with two tiny teethes, differing in this aspect from the type material and specimens analyzed in the Marimbus do Baiano.

Bourrellyodesmus comperei also presents some morphological similarities between the lateral and apical views of B. jolyanus (C.E.M.Bicudo & M.T.P.Azevedo) C.E.M. Bicudo & Compère (1978: 416) and B. guarrerae S.M.M.Faustino & C.E.M.Bicudo (2004: 669) , both of which are described in São Paulo, Brazil. The former differs by having an apical view with 2 intramarginal granules on each side, near the spines, and 1 median swelling, and by the largest size (23.0–27.0 μm × 21.0–24.0 μm); whereas the latter species differs in lateral view by having a short acute spine on granule located in the center of each semicell. Therefore, we consider that these morphological differences are enough to describe our material as a new species.

The new Brazilian species resembles X. concinnum var. floridense A.M. Scott & Grönblad (1957: 30) in frontal view, but it differs by having a short spine at each angle of semicells, which are oblong in apical view.

Analyzing the geographical distribution of the genus Bourrellyodesmus , we noticed that almost all taxa are from tropical areas, and Brazil could be an important center of diversity of the genus, with five species currently reported in the country.

Figures

FIGURES 1–6. Line drawings. 1. Bourrelyodesmus comperei sp. nov. 2. Xanthidium concinnum var. longispinum var. nov. 3. Xanthidium mamillosum var. mediolaeve. 4. Xanthidium nordstedtii. 5. Xanthidium regulare var. asteptum. 6. Xanthidium trilobum.

FIGURES 8–30. Bourrelyodesmus comperei sp. nov. (8–16): frontal view (8, 11, 13–16), lateral view (9), apical view (10, 12), morphological variation (13–16). Xanthidium concinnum var. longispinum var. nov. (17–24): frontal view (17, 20, 23–24), lateral view (18, 21), apical view (19, 22), morphological variation (23–24). Xanthidium mamillosum var. mediolaeve (25–30): frontal view (25, 28), empty cell after reproduction (26), zygospore (27), lateral view (29), apical view (30). Scale Bar: 10 μm, except Fig. 25, 28–30 (40 μm), Fig. 26–27 (50 μm, horizontal bar).