Nitella acuminata A. Braun ex Wallman (1853: 35)

Borges, Fabio Renato & Jr, Orlando Necchi, 2018, Taxonomy and phylogeny of Nitella (Charophyceae, Characeae) from Brazil with emphasis on the midwest and southeast regions, Phytotaxa 356 (3), pp. 181-198 : 187-189

Nitella acuminata A. Braun ex Wallman (1853: 35)

Figs. 5–10 .

Plants monoecious, up to 35 cm high, without calcium carbonate deposition.Axes 151–1058 μm in diameter, internodes 0.05–6.7 cm long, 0.14–4.58 (mean 1.25) times as long as the branchlets. Sterile and fertile branchlets similar or different in shape; sterile branchlets (5–)7–9(10) in a whorl, 0.2–4.0 cm long, 1 furcated; rays (5–)7–9(10), 0.05–2.00 cm long, 131–773 μm in diameter; fertile branchlets similar in shape to sterile branchlets, but smaller in length and diameter, and located near apices or forming heads. Dactyls (2)3–4(–6), 1 celled, abbreviated or no, 0.03–1.10 cm long, 55–540 μm in diameter, cylindrical with acuminate apex. Heads, when present, 1-several, terminal or axillary, from loose to compact. Gametangia sejoined or conjoined at fertile branchlets nodes and/or at heads, without mucus. Oogonia 1–3 at a node, 148–496 μm long (excl. nucula), 150–413 μm in wide; convolutions 6–8(9); coronula 24–48 μm high, 42–71 μm wide at base, upper cells usually higher than basal cells; coronular cells convergent, persistent. Oospores brown to dark brown, 211–322 μm long, 181–324 μm wide; striae (5)6–7(8); fossa 28–64 μm across; membrane finely granulate under LM and granulate (only for sample SJRP32572) or scabrous under SEM (all other samples). Antheridia solitary, 126–377 μm in diameter, 8 scutate.

Specimen examined:— BRAZIL. Goiás: BR 070, between the municipalities of Aragarças and Jussara, elev. 339m, 15°51’26.3”S, 51°36’9.5”W, 15 April 2015, coll. F. R. Borges (SJRP32572). Mato Grosso: São Nicolau Farm, Municipality of Cotriguaçu, 09°49’27.1’’S, 58°15’27.0’’W, 25 May 2011, coll. F. R. Borges (SJRP32542). MT10, Municipality of Rosário do Oeste, 14°52’58.5’’S, 56°22’24.8’’W, 11 May 2014, coll. F. R. Borges (SJRP32528). District of Primaverinha, BR163, between the Municipalities of Sorriso and Lucas do Rio Verde, 12°50’43.2’’S, 55°49’32.6’’W, 11 May 2014, coll. F. R. Borges (SJRP32549). Mato Grosso do Sul: Entrance to Recanto Ecológico do Rio da Prata, BR267, Municipality of Jardim, 21°29’21.1’’S, 56°26’16.6’’W, 15 May 2014, coll. F. R. Borges (SJRP32555). Entrance to Recanto Ecológico do Rio da Prata, BR267, Municipality of Jardim, 21°29’21.1’’S, 56°26’16.6’’W, 15 May 2014, coll. F. R. Borges (SJRP32556). Entrance of Araras Farm, BR163, Municipality of Coxim, 18°19’5.9’’S, 54°39’56.1’’W, 12 May 2014, coll. F.R. Borges (SJRP32552).BR163, between the Municipalities of Sonora and Coxim, 17°54’40.5’’S, 54°41’24.1’’W, 12 May 2014, coll. F.R. Borges (SJRP32550). Minas Gerais: BR 369, Municipality of Campos Gerais, elev. 864m, 21°13’39.00’’S; 45°38’51.85’’W, 30 September 2015, coll. F.R. Borges (SJRP32573). São Paulo: Municipality of Neves Paulista, elev. 530m, 20°50’54.6’’S, 49°34’13.7’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32565). Municipality of Potirendaba, elev. 443m, 21°00’40.1’’S, 49°24’40.7’’W, 3 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32529). Municipality of Neves Paulista, elev. 463m, 20°56’48.0’’S; Long: 49°41’09.6’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32564). Borá stream, José Domingues Neto Avenue, Municipality of Cedral, elev. 480m, 20°57’03.2’’S, 49°20’58.8’’W, 3 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32531). Talhadinho Stream, District of Talhados, Municipality of São José do Rio Preto, elev. 502m, 20°43’45.5’’S, 49°17’51.3’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32533). Talhadinho Stream, District of Talhados, Municipality of São José do Rio Preto, elev. 502m, 20°43’45.5’’S, 49°17’51.3’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32560). Municipality of José Bonifácio, elev. 440m, 21°00’44.1’’S, 49°41’21.6’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32561). Municipality of Potirendaba, elev. 446m, 21°01’48.9’’S, 49°23’07.5’’W, 3 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32561). Municipality of José Bonifácio, elev. 440m, 21°00’44.1’’S, 49°41’21.6’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32562). Municipality of Ruilândia, elev. 445m, 20°55’40.4’’S; 49°32’30.9’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32562). Municipality of Potirendaba, elev. 475m, 21°00’04.4’’S, 49°25’05.8’’W, 3 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32534). Municipality of Potirendaba, elev. 446m, 21°01’48.9’’S, 49°23’07,5’’W, 3 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32519). Municipality of José Bonifácio, elev. 458m, 20°59’08.0’’S, 49°40’48.8’’W, 4 September 2014, colls. F. R. Borges and O. Necchi Jr. (SJRP32563).

DNA sequences: rbc L- MG010425, MG029152, MG020112, MG010430, MG010428, MG010429, MG020113, MG010426, MG020122, MG010427, MG029156, MG020114, MG029153, MG020118, MG020116, MG020115, MG020117, MG020119, MG029155, MG020121, MG029154, MG020120; ITS2- MG029129, MG029130, MG029134, MG029135, MG029136, MG029133, MG029131, MG029132, MG029137.

Brazilian samples could be identified, based on morphology, in three distinct species. Samples SJRP32528, SJRP32542, SJRP32549, SJRP32552, SJRP32555, SJRP32556 and SJRP32565 had long dactyls and absence of heads, typical characteristics of N. acuminata ( Wood & Imahori 1965) . In contrast, samples SJRP31519, SJRP31520, SJRP32529, SJRP32531, SJRP32533, SJRP32534, SJRP31537, SJRP32550, SJRP32560, SJRP32561, SJRP32562, SJRP32563, SJRP32564 and SJRP32573 had long dactyls and loosely arranged heads( Fig. 5 ), typical of N.subglomerata ( Wood & Imahori 1965) . And sample SJRP32572 showed dactyls abbreviated ( Fig. 7 ), barely visible to naked eyes and dense fertile heads (axillary, rarely terminal, Fig. 6 ), typical of N. gollmeriana ( Wood & Imahori 1965) . Despite these data, phylogenetic trees for rbc L ( Fig. 2 ) and ITS2 ( Fig. 4 ) exhibited no clear distinction among the sequences of those samples, which were in the same clade with high support.

Figures

FIGURE 2. Maximum likelihood Phylogenetic tree based on rbcL sequences.The numbers associatedwith the nodes indicate the bootstrap values (BS) for maximum likelihood and posterior probability (PP) for Bayesian analysis; nodes without values indicate BS <70% and PP <0.70; nodes with * indicate BS> 95% and PP>0.95 Sequences in bold are the new sequences generated in this study. Samples marked with “1” can be morphologically identified as N. acuminata (Wood & Imahori 1965); “2” with N. subglomerata (Wood & Imahori 1965).

FIGURE 4. Bayesian Phylogenetic tree based on ITS2 sequences. The numbers associated with the nodes indicate the bootstrap values (BS) for maximum likelihood and posterior probability (PP) for Bayesian analysis; nodes without values indicate BS <70% and PP <0.70; nodes with * indicate BS> 95% and PP>0.95 Sequences in bold are the new sequences generated in this study. Samples marked with “1” can be morphologically identified as N. acuminata (Wood & Imahori 1965); “2” with N. subglomerata (Wood & Imahori 1965).

FIGURES 5–10. Nitella acuminata. 5. Upper whorls with loosely compacted heads (a diagnostic feature of N. subglomerata). 6. Compacted heads (a diagnostic feature of N. gollmeriana). 7. Dactyls 1-celled, abbreviated with acuminate apex (a diagnostic feature of N. gollmeriana). 8. Oospore membrane with finely granulate aspect under LM. 9. Overview of an oospore under SEM. 10. Oospore membrane with scabrous aspect under SEM.