taxonID	type	description	language	source
5921D53AFFFBAC0347A8FD97FED8F9CA.taxon	diagnosis	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 spines 15 – 17 µm, thickness 7 – 9 µm, isthmus 4 – 6 µm, spines 1 – 1,2 μm long.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFFBAC0347A8FD97FED8F9CA.taxon	materials_examined	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).	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFFBAC0347A8FD97FED8F9CA.taxon	etymology	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.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFFBAC0347A8FD97FED8F9CA.taxon	diagnosis	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.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF9AC0847A8F96AFD9AFCCA.taxon	diagnosis	Diagnosis: — It differs from the nominate variety by having a long spine in each lateral margin, a pair of minute spines on the apical margin, and the face of the semicells has a central protrusion, ornamented with a spine with an inflated base. Cell dimensions: length without spines 11 – 13 μm, with spines 12 – 16 μm, width without spines 9 – 14.6 μm, with spines 18 – 23 μm, thickness 8 – 9 µm, isthmus 3 – 4 μm, lateral spines 3.5 – 5.3 μm long.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF9AC0847A8F96AFD9AFCCA.taxon	materials_examined	Holotype: — Material numbered (HUEFS 253751!) [pro parte], deposited at Herbarium of State University of Feira de Santana. Population partially illustrated here (Figs. 2, 17 – 24). Paratypes: — Material numbered (HUEFS 253744, HUEFS 253747) [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 ’ 33.2 ” S, Long. 41 ° 18 ’ 29.1 ” W, 18 February 2018, M. A. Santos, J. T. X. Neto & F. M. Costa s / n (HUEFS 253751). Habitat: — The new species was rarely found in the study area, occurring generally associated to periphyton of Cabomba caroliniana and Utricularia foliosa; EC 0.01 mS. cm- 1 (± 0.01); DO 6.4 (± 0.7); TDS 0.02 (± 0.02); pH 6.9 (± 0.4); T 32 ° C (± 0.5); WT 63 cm (± 20.7).	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF9AC0847A8F96AFD9AFCCA.taxon	etymology	Etymology: — The varietal epithet refers to the long spines present in the lateral margins of semicells.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF9AC0847A8F96AFD9AFCCA.taxon	diagnosis	Differential diagnosis: — Morphologically, the newly described variety resembles Xanthidium concinnum var. boldtianum West (1892: 167, as ‘ boldtiana ’) and Xanthidium concinnum var. scottii C. E. M. Bicudo in Prescott et al. (1982: 62). However, the former differs by having no short apical spines on each apical angle and central obtuse protrusion on the face of semicells, whereas the latter differs by having downward-projected spines at the lateral margins and the mid-region of the semicells.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF9AC0847A8F96AFD9AFCCA.taxon	description	In addition to Bahia, the var. longispinum has been registered in the State of Mato Grosso do Sul by Paula et al. (2014: 428, figs. 50, 51), but as a misapplied name X. concinum W. Archer (1883: 285), based on specimens collected from the Upper Paraná River floodplain.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF2AC0847A8FC69FCCEF84B.taxon	materials_examined	Material examined: — BRAZIL. Bahia: Andaraí, Marimbus do Baiano, Lagoa do Baiano. Samples: HUEFS 253745. Habitat: — Taxon was rare in Marimbus do Baiano, found associated only to U. foliosa; EC 0.04 mS. cm- 1; DO 6.6; TDS 0.03; pH 7.0; T 31.4 ° C; WT 36 cm; Taxonomic notes: — This taxon was originally proposed by Grönblad (1945: 22) from specimens collected in Santarém, Pará State, Amazon Basin, as X. antilopaeum var. mamillosum f. mediolaeve. Later, Couté & Tell (1981: 197) raised that form to a varietal level: X. mamillosum var. mediolaeve. Morphologically, var. mediolaeve differs from the nominate variety by not having a spine in the midregion of semicells, and smallest cell dimensions (Prescott et al. 1982). It somewhat resembles X. mamillosum var. sexaculeatum (Grönblad) Kurt Förster (1969: 62), but this latter variety differs by having basal angles of semicells decorated by the single spine, and a ring of pores around a central one, visible in the apical view (Förster 1969). Thomasson (1971), studying material from X. mamillosum collected in Maica Lake (Santarém, Pará) and Rio Preto da Eva Lake (Rio Preto da Eva, Amazonas), Amazon Basin, observed that taxa have a typical mamillate base, and some specimens have 1 – 2 frontal spines. The author considered that all forma under X. mamillosum described by Grönblad (1945), besides X. canadense var. borgei Kurt Förster (1981: 247), are considered to belong within the morphological range of the species. Until molecular studies to be conducted to verify the delimitation of the varieties of X. mamillosum, we consider more appropriate to maintain var. mediolaeve as a distinct taxon. The zygospore of X. mammilosum var. mediolaeve analyzed resembles to format observed in X. trilobum, except by absence apical furcated spines. Details of the scanning electron microscopy (SEM) of the var. mediolaeve were presented by Couté & Tell (1981: 207, Pl. 3, fig, 7 – 8), showing smooth facial semicells, punctuated cell walls, and spines with a characteristic mamillate base, similar to the specimens analyzed under photonic microscopy in the present study (Figs. 25, 28). In Brazil, aside from the type locality, the taxon under discussion has also been reported in Bahia (Oliveira et al. 2011), Mato Grosso (De-Lamonica-Freire 1992), Paraná (Paula et al. 2014), and São Paulo (Bicudo et al. 2018), all reported as X. antilopaeum var. mamillosum f. mediolaeve.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF3AC0947A8FFBEFCEBF7DE.taxon	description	(Figs 4, 31 – 39, 66)	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF3AC0947A8FFBEFCEBF7DE.taxon	description	Cell dimensions: — length without spines 48 – 55 μm long, with spines 70 – 86 µm, width without spines 38 – 45 μm, with spines 60 – 90 μm, isthmus 11.5 – 14.5 μm, thickness 27 – 28 µm, spines 15 – 28 μm long.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF3AC0947A8FFBEFCEBF7DE.taxon	materials_examined	Material examined: — BRAZIL. Bahia: Andaraí, Pantanal dos Marimbus, Lagoa do Baiano. Samples: HUEFS 253741, HUEFS 253742, HUEFS 253751, HUEFS 253752, HUEFS 253759, HUEFS 253766, HUEFS 253775, HUEFS 253777, HUEFS 253783, HUEFS 253804, HUEFS 253808.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF3AC0947A8FFBEFCEBF7DE.taxon	biology_ecology	Habitat: — In the study area, this taxon was occasionally found associated to C. caroliniana and U. foliosa, and rarely to N. amazonum; EC 0.02 mS. cm- 1 (± 0.01); DO 7.2 (± 1.5); TDS 0.02 (± 0.01); pH 7.0 (± 0.9); T 30.4 ºC (± 2); WT 65.9 cm (± 17); N-NO 2 0.013 (0.005 ±); N – NO 3 0.024 (± 0.016); N-NH 4 0.027 (± 0.019); P – PO 4 0.019 (± 0.013); O 4 Si- 4 0.506 (± 0.470).	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF3AC0947A8FFBEFCEBF7DE.taxon	discussion	Taxonomic notes: — This taxon was initially described by Grönblad (1945: 22, Pl. 7, fig. 152) for Santarém, Pará, Brazil, as Xanthidium antilopaeum var. nordstedtii and included X. antilopaeum forma (Nordstedt 1878: 27, fig. 6) as a synonym of it. Grönblad characterized the taxon as having oblong semicells, open sinus, rounded ends, bearing 6 spines, single apical and double basal, transverse parallel to perpendicular, with an inflated base, and oblongrectangular in apical view. Polyphasic study performed by Šťastný et al. (2013) with X. antilopaeum Kützing (1849: 177) from various European localities showed that the taxon forms a monophyletic lineage, composed by four monophyletic clades, characterized by wide cells with eight spines per semicell, differing from each other because of the arrangement of the spines, cell dimensions, and the pattern of the central ornamentation. Morphologically, X. antilopaeum var. nordstedtii differs from the nominate variety by having six spines per semicell, a single in each apical angle and two in the basal ones, with longer spines and semicell more rotund in apical view (Scott et al. 1965) and no central scrobiculae on face of semicells. Grönblad & Scott in Scott et al. (1965: 48) raised the X. antilopaeum var. nordstedtii to species level, as X. nordstedii, and characterized it as having semicells broadly ovate, spines with swollen base, with two basal spines extending horizontally, and an apical spine directed outwardly and slightly upward; tumid apical view (Scott et al. 1965, fig. 136 – 137). A couple of years later, Förster (1969: 62) reduced that species to variety of X. mamillosum Förster (1964: 411 as ‘ mammillosum’), distinguishing it from the nominate variety by having no spine on the face of the semicells and having tumid cells in apical view. According to Thomasson (1971: 43), X. mamillosum differs from X. nordstedtii by having spines rising from a swollen base, which is absent in the latter species. The author also commented on the morphological similarity of X. antilopaeum var. ayayense Grönblad (1945: 210, Pl. 7, fig. 146) with X. nordstedtii, and except for the tumid apical view in the latter, there are no differences between both taxa, which we fully agree. In the present study, we observed some slight tumid semicells in the apical view and slight swelling at the base of the spines, although in others, it was difficult to distinguish, especially when the focus had not been properly applied. Furthermore, we observed variations in the size of the spines, since longer (22 – 28 μm) in some individuals to shorter (15 – 18 μm) in others. Couté & Tell (1981: 196) carried out a SEM study from material collected in Argentina and Guyana, and identified the taxon under discussion as X. mamillosum var. borgei Kurt Förster (1981: 247). Based on the images provided by the authors (Pl V, fig. 3 – 5), it is possible to observe semicells with punctuated walls, bearing six spines with slight swelling at the base. Thus, we consider it is more appropriate to accommodate that taxon as X. nordstedtii than as X. mamillosum var. borgei, the latter a misapplied name. This material was quite similar to the SEM image obtained from Bahia (Fig. 66). In addition to the type locality (Santarém, Pará), the taxon was registered in the states of Amazonas (Thomasson 1971), Bahia (Oliveira et. al. 2011, as X. antilopaeum f.), Pará (Grönblad 1945; Scott et al. 1965; Förster 1969, 1974, 1981, as X. mamillosum var. nordstedtii), Minas Gerais (Nordstedt 1878, as X. antilopaeum f.), and São Paulo (Bicudo et al. 2018, as X. antilopaeum f.). It was the most common Xanthidium taxon in Marimbus do Baiano, occurring in 44 % of the samples and registered in all macrophytes studied.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF0AC0A47A8FFBDFBDFFB26.taxon	description	Habitat: — This taxon was occasionally found in study area associated to C. caroliniana and U. foliosa; EC 0.01 (± 0.01) mS. cm- 1; DO 6.5 (± 0.8); TDS 0.02 (± 0.02); pH 7.8 (± 1); T 29.6 ºC (± 2); WT 62 cm (± 16).	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF0AC0A47A8FFBDFBDFFB26.taxon	materials_examined	Material examined: — BRAZIL. Bahia: Andaraí, Pantanal dos Marimbus, Lagoa do Baiano. Samples: HUEFS 253753, HUEFS 253754, HUEFS 253756, HUEFS 253757, HUEFS 253766, HUEFS 253768, HUEFS 253772, HUEFS 253775, HUEFS 253801. Taxonomic notes: — Morphologically, Xanthidium regulare var. asteptum resembles X. regulare var. pseudoregulare (Borge) C. E. M. Bicudo & L. M. Carvalho (1969: 374, figs 10 – 12), although the latter differs by having semicells furnished by a single robust spine, which is 2 – 4 divided at the distal end, and having no tiny spine beneath each angle of the semicells. We observed that zygospore of X. regulare var. asteptum without spines presents a cell more inflated (75 – 80 μm) than other of Xanthidium taxa analyzed in Marimbus do Baiano (ca. 50 μm), and distinct by ornamented by short, robust and pointed spines. Couté & Tell (1981: 214, Pl. 10, fig. 4 – 5) presented details in the SEM of X. regulare var. asteptum, showing angles of semicells ornamented by solid spines bifid or trifid ones, curved, unequal, and a tiny spine in the basal angles of the semicells. Although the type locality of this taxon is São Paulo (southeastern Brazil), the var. asteptum has been commonly reported in the northern Brazil (Amazonas, Amapá, Pará, Tocantins, Roraima), and sometimes in other regions such as northeastern (Maranhão, Pernambuco, Bahia), and Central-West (Mato Grosso).	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF0AC0B47A8FA3DFDACFC96.taxon	description	Xanthidum triblobum var. laeve Lemmermann (1914: 216, fig. 14) Cell dimensions: — length 48 – 62 μm (without spines), 61 – 89 μm (including spines), width 43 – 60 μm (without spines), 52 – 85 μm (including spines), thickness 18 – 25 µm, isthmus 10 – 18 μm, spines 5 – 13 μm long. Zygospore 110 µm in diameter (including spines), globular in shape and provided with long, apically furcated spines. Habitat: — This species was common in study area, and found associated to C. caroliniana, N. amazonum and U. foliosa; EC 0.02 mS. cm- 1 (± 0.01); DO 6.9 (± 1.2); TDS 0.02 (± 0.01); pH 7.1 (± 1.1); T 30 ° C (± 2.3); WT 68.7 (± 14) cm.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF0AC0B47A8FA3DFDACFC96.taxon	materials_examined	Material examined: — BRAZIL. Bahia: Andaraí, Pantanal dos Marimbus, Lagoa do Baiano. Samples: HUEFS 253741, HUEFS 253746, HUEFS 253754, HUEFS 253756, HUEFS 253765, 253766, HUEFS 253768, HUEFS 253781, HUEFS 253796, HUEFS 253802, HUEFS 253811. Taxonomic notes: — Xanthidium trilobum was described by Nordstedt (1870: 230) based on specimens from Lagoa Santa (Minas Gerais). This species is characterized by the presence of trilobate semicells angles with forked spines, and a central protrusion on the face of semicells ornamented by granules. This taxon has been reported in several Brazilian regions: South (Paula et al. 2014), Southeast (Børgesen 1891; Lemmermann 1914, as X. trilobum var. laeve Lemmermann; Borge 1899, 1918; Bicudo et al. 2018) Midwest (Borge 1925; Camargo et al. 2009; De-Lamonica-Freire 1992), Northeast (Oliveira et al. 2011), and North (Grönblad 1945; Förster 1964, 1969, 1974, Thomasson 1971, Bittencourt-Oliveira 1993, Lopes & Bicudo 2003; Souza & Melo 2011), in which morphological variation can be seen on the margins between the basal and polar lobes, right to rounded angles; apical margin, retuse to rounded; protrusion on the face of the semicell from shallow to projected, and ornamented by obtuse granules or granules with spiniform ends. Some specimens identified in the present study are similar to those illustrated by Thomasson (1971, Pl. 16, fig. 14) and Grönblad (1945, Pl. 8, fig. 148) from specimens collected in the Amazon region. Morphologically, Xanthidium trilobum resembles X. subtrilobum West & G. S. West (1897: 88), especially because of the shape of the cell, although the latter differs by having semicells with a spine not forked at the angles of the lobes, and the presence of a spine in the middle of the outer margin of each lateral lobe in apical view. The zygospore with long, apically furcated spines analyzed in the Marimbus do Baiano were similar to reported by Coesel (1988) for the material collected in a shallow pool in Eskol, municipality of Roura, south of Cayenne, French Guiana. The SEM images of X. trilobum cells observed (Fig. 67) resembles to material studied to the Argentina by Couté & Tell (1981: 214, Pl. 10, fig. 3), showing the facial semicells ornamented by a circle of nine granules surrounding a central one, and semicells with projected angles in short cylindrical processes, with 2 spines at the end. Coesel (1996), analyzing the biogeography of desmids, commented the possibility that Xanthidium trilobum and X. subtrilobum have been sister taxa, the former reported from South and Central America, whereas the latter known from Africa, S. E. Asia, and N. Australia; and that the differences in morphology between both taxa occurred by supposed allopatric speciation by the dispersal model (colonization) rather than by the vicariance model (fragmentation). Xanthidium trilobum was the second most common taxon of the genus in the study area and registered in approximately 37 % of all analyzed samples.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF1AC0C47A8FC4DFD2FFF0B.taxon	diagnosis	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.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF1AC0C47A8FC4DFD2FFF0B.taxon	materials_examined	Holotype: — Material numbered (HUEFS 253753!) [pro parte], deposited at Herbarium of State University of Feira de Santana, population partially illustrated here (Figs 7, 52 – 62). Paratype: — Material numbered (HUEFS 253766) [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. Santos, J. T. X. Neto & F. M. Costa s / n (HUEFS 253753). 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.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF1AC0C47A8FC4DFD2FFF0B.taxon	etymology	Etymology: — The specific epithet refers to the surface ornamentation composed of warts arranged on the face of the semicells.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
5921D53AFFF1AC0C47A8FC4DFD2FFF0B.taxon	diagnosis	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.	en	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): 228-242, DOI: 10.11646/phytotaxa.536.3.3
