Chaetogastra cogniauxiana F.S.Mey. & R.Goldenb., 2021

Meyer, Fabrício Schmitz & Goldenberg, Renato, 2021, Chaetogastra cogniauxiana (Melastomataceae), a new Brazilian species from the Chaetogastra gracilis complex, Phytotaxa 511 (3), pp. 261-274 : 263-272

Chaetogastra cogniauxiana F.S.Mey. & R.Goldenb. sp. nov. ( Figures 2−4 ).

Type:― BRAZIL. Paraná, Balsa Nova, São Luiz do Purunã , 16 October 2005, R . Goldenberg & F. A . Michelangeli 703 (holotype: UPCB!; isotypes: MBM!, NY!) .

= Tibouchina gracilis ( Humboldt & Bonpland, 1823: 138) Cogniaux (1885: 386) var. gracillima Cogniaux (1885: 387) . Lectotype:― BRAZIL. Undetermined locality, s.d., F. Sellow s.n. (BR, barcode 00000552054!, designated by Guimarães et al. 2019), syn. nov.

= Tibouchina gracilis ( Humboldt & Bonpland, 1823: 138) Cogniaux (1885: 386) var. longisetosa Cogniaux (1885: 388) , syn. nov — Lectotype:― BRAZIL. Undetermined locality, s.d., F. Sellow 1216 (K, barcode 000329073!, designated by Guimarães et al. 2019), syn. nov.

Diagnosis: — Chaetogastra cogniauxiana differs from C. gracilis by the smaller size, 10–70 cm tall (vs. 30–120 cm tall in C. gracilis ), dendritic-setose to dendritic-strigose hypanthium and bracteoles (vs. dendritic-sericeous hypanthium and bracteoles), and smaller petals, 9.8–13.4 × 8.8–9.1 mm (vs. larger petals, 16.5–21.6 × 11.2–14.8 mm).

Description: —Subshrubs with sympodial growth, poorly branched, 10–70 cm tall; stem lacking a stolon with small leaves on the basal portions. Branches moderately dendritic-hirsute, dendritic-setose, or dendritic-strigose, trichomes 1.3–4.6 mm long, glandular or not glandular (often mixed), curved, erect, or appressed, base rounded, slightly enlarged to enlarged, not immersed, not forked. Petioles 1–5.2 mm long; blades 2.1–7.8 × 0.6–2.3 cm, chartaceous, elliptic-lanceolate or lanceolate, surface flat or rarely conduplicate, facing upwards or rarely patent on dry specimens, apex acute, base obtuse, margins crenulate, ciliate, trichomes 1.1–3 mm long, not glandular or glandular (often mixed), appressed to curved, the base linear, slightly broadened, immersed, not forked, adaxial surface moderately dendriticstrigose, trichomes arranged along the entire surface, 1.2–5.6 mm long, not glandular or glandular (often mixed), appressed or curved, the base linear, not broadened, immersed, either forked or not forked, followed by a sequence of white dots, abaxial surface moderately dendritic-strigose, trichomes arranged along the entire surface, trichomes 1.5–3.7 mm long, glandular or not glandular (often mixed), appressed, the base slightly broadened, immersed, either forked or not forked, followed by a sequence of white dots; veins 3–5, if five, first and second lateral pairs confluent, veins on the abaxial surface of the leaves moderately dendritic-setose, trichomes 1.9–3.6 mm long, glandular or not glandular (often mixed), curved, the base slightly broadened, immersed, not forked, followed by a sequence of white dots. Thyrsoids 7.3–19.1 cm long, internode of the inflorescence base 3.9–10.8 cm long, cymes axillary and terminal, flowers congested to lax (depending on the maturation stage of the inflorescence); bracteoles 2.2–4.6 × 0.9–1.9 mm, ovate, oblong or elliptic-lanceolate, abaxial surface moderately to sparsely dendritic-strigose, trichomes 0.7–2.2 mm long, not glandular or glandular (often mixed), appressed, the base rounded, not broadened to slightly broadened, not immersed, not forked, adaxial surface glabrous, margins moderately to sparsely dendritic-strigose, trichomes 1.9–4 mm long, not glandular or glandular (often mixed), erect, the base rounded, slightly broadened, not immersed, not forked. Flowers 4–5(–6)-merous, 2.7–3.5 cm in diameter; hypanthium 3.1–5 × 2.3–3.8 mm, epidermis not completely covered by the indument, yellow–green, smooth (not longitudinally striated), obovate, apically slightly constricted, moderately dendritic-setose to dendritic-strigose, trichomes 1.4–4.9 mm long, glandular or not glandular (often mixed), appressed to curved, the base slightly broadened, not immersed, not forked; sepals 3.8–6 × 1.7–1.9 mm, narrowly triangular but with a wide base, apex acuminate, abaxial surface with the indumentum similar to the hypanthium, but concentrated along the central portion, adaxial surface glabrous, margins ciliate, with more elongated trichomes at the apex, trichomes 1.2–3.7 mm long, not glandular or glandular (often mixed), curved to erect, the base broadened, slightly enlarged, not immersed, not forked; petals 9.8–13.4 × 8.8–9.1 mm, pink, purple, light pink, or seldom white, obovate, apex cuspidate, obtuse, or truncate, margins short-ciliate, trichomes 0.1–0.3 mm long, glandular and not glandular (often mixed), erect, the base linear, not broadened, not immersed, not forked; stamens 8–10(–12), antepetalous with filaments 4.2–5.7 mm long, white (during anthesis) or purple (in senescent flowers), glabrous, pedoconnective 0.3–0.5 mm long, ventral appendages 0.3–0.4 mm long, entirely yellow, obtuse at the apex, anthers 3.2–5 mm long, entirely yellow, apex attenuate, pore ca. 0.3 mm wide, antesepalous with filaments 5.4–7.5 mm long, white (during anthesis) or purple (in senescent flowers), glabrous, pedoconnective 0.5–0.8 mm long, ventral appendages 0.4–0.6 mm long, entirely yellow, obtuse at the apex, anthers 3.6–6.9 mm long, entirely yellow, apex attenuate, pore ca. 0.3 mm wide; ovary 3.6–4.4 × 2.5–3.2 mm, apex densely sericeous, with trichomes 0.4–1.7 mm long, glandular or not glandular (often mixed), erect, the base linear, not broadened, not immersed, not forked; style 9.7–15.4 mm long, apex curved, glabrous. Capsules 11.7–14.2 × 6.1–7.2 mm, smooth (without longitudinal ribs), beige or brown.

Paratypes: — BRAZIL. Undetermined State: undetermined locality, s.d., Riedel s.n. ( NY barcode 00514856!), undetermined locality, s.d., Riedel s.n. ( P barcode 05200601!), idem ( P barcode 05200608!), undetermined locality, s.d., Sellow s.n. ( BR barcode 00000552023-branch number 01, on the right side!), undetermined locality, s.d., Sellow s.n. ( S 15-11854 online image), undetermined locality, s.d. Riedel 1784 ( K, branch to the right side of the exsiccatum!) . Paraná: Undetermined Municipality , 29 November 1910, P . Dusén 10868 ( S online image), 10 January 1967, J. C . Lindeman 3973 ( K!, NY!, US online image) , 18 February 1904, P . Dusén s.n. ( S 15-11233 online image), 20 November 1984, J . Mattos 26656 ( HAS!), 30 November 1989, J . Mattos 26528 ( HAS!), 24 February 1910 P . Dusén 10813

the branches and hypanthium. E. Bracteole, abaxial surface. F. Hypanthium and sepals, without stamens, style and sepals. G. Hypanthium and sepals (adaxial surface) seen from a longitudinal section of the hypanthium. H. Antesepalous stamen. I. Antepetalous stamen. J.

Gynoecium. (A–K: based on Meyer & Simão 1775 at UEC).

(S online image, US online image); Almirante Tamandaré, 10 January 1967, G. Hatschbach 15632 (MBM!) ; Balsa Nova, 12 November 1980, G. Hatschbach 43329 (MBM!) , 3 January 1999, S. R. Ziller 1957 (EFC!, MBM!) , 8 January 2003, E. E. Kauano 9 (MBM!) , 24 November 2012, F. S. Meyer 1411 (UEC!, UPCB!) , F. S. Meyer 1412 (UEC!) , F. S. Meyer 1413 (UEC!, UPCB!) , F. S. Meyer 1414 (UEC!, UPCB!) , F. S. Meyer 1417 (UEC!, UPCB!) , F. S. Meyer 1424 (UEC!) , F. S. Meyer 1425 (UEC!) , F. S. Meyer 1426 (UEC!) , F. S. Meyer 1430 (UPCB!) , 4 December 2013, E. D. Lozano 2164 (MBM!) ; Campo Largo, 10 January 1977, L. T. Dombrowski 6921 ( US online image) , 10 January 1977, L. T. Dombrowski 6956 ( US online image) , 12 March 1999, R. Goldenberg 500 (MBM!) ; Carambeí, 2 November 2013, E. D. Lozano 1705 ( FLOR online image, HCF!, MBM!) ; Castro, 4 November 1960, E. Moreira 10 ( US online image); Cerro Azul , 27 January 1970, G. Hatschbach 23420 (NY!, UPCB!, US online image) , 19 November 1988, S. R. M. Patriota s.n. ( SP 338632!); Colombo , 12 January 1984, A. Bidá 254 ( UB!) , 22 November 2011, J. R. Nascimento 18 (IRAI!) ; Curitiba, 19 October 1928, F. C. Hoehne s.n. ( SP 23068 !) , 5 January 1952, N. Imaguire 2694 ( US online image) , December 1964, L. T. Dombrowski 1270 ( US online image) , 6 January 1967, L. T. Dombrowski 2239 ( US online image) , 4 December 1970, L. T. Dombrowski 3207 ( US online image) , 16 December 1975, L. T. Dombroswki 6215 (P!) , 25 November 2012, F. S. Meyer 1441 (UEC!) , 25 November 2012, F. S. Meyer 1443 (UEC!, UPCB!) , 21 December 2013, F. S. Meyer 1775 (UEC!, UPCB!) , F. S. Meyer 1777 (UEC!, UPCB!) , F. S. Meyer 1778 (UEC!) , F. S. Meyer 1779 (UEC!) , F. S. Meyer 1784 (UEC!) , 30 December 2014, F. S. Meyer 2105 (UPCB!) ; Jaguariaíva, August 1914, P. Dusén s.n. ( S 15-11658 online image) , 7 November 1928, F. C. Hoenne s.n. ( SP 23472 !) , 2 November 1989, A. C. Cervi 2965 (MBM!) , 2 November 1998, O. S. Ribas 2772 (G!, MBM!) , 13 October 2006, J. M. Silva 5113 (MBM!) ; Lapa, 30 November 1989, O. S. Ribas 208 (MBM!) , 1 October 2011, R. Ristow 1770 (IRAI!) , 23 November 2013, M. E. Engels 1999 (HCF!) , 4 January 2016, F. S. Meyer 2136 (UPCB!) ; Palmas, 13 December 2013, M. E. Engels 2201 (MBM!) , 8 January 2016, F. S. Meyer 2179 (UPCB!) ; Palmeira, 4 February 1999, G. Hatschbach 68938 (EFC!, MBM!) , 10 December 2013, E. D. Lozano 2188 (MBM!) ; Piraí do Sul , 28 December 1903, P. Dusén s.n. ( S 15-11657 online image) , 29 March 2013, F. S. Meyer 1725 (NY!, UEC!, UPCB!) , 27 November 2013, E. D. Lozano 1962 (MBM!) , 11 December 2013, R. S. Moro s.n. ( HUPG 20576 !); Piraquara , 8 December 1946, G. Hatschbach 555 (HAS!, MBM!, SP!) , 9 December 1947, G. Tessmann 2707 (MBM!) , 5 April 1979, G. Hatschbach 42183 (MBM!, US online image) , 13 November 1992, S. R. Ziller 392 (EFC!) ; Ponta Grossa, s.d., G. Gehrt s.n. ( SP 3719 !) , 1 November 1928, F. C. Hoehne s.n. ( SP 23257 !) , 9 November 1966, P. Occhioni 3475 ( US online image) , 8 December 1967, H. M. Filho 439 (NY!) , October 1970, R. Occhioni 4277 ( US online image) , 26 November 1972, P. Occhioni 5362 ( US online image) , 18 November 1985, Y. S. Kuniyoshi 4937 (EFC!) , 16 January 1987, A. Kaprovickas 40903 ( US online image) , September 1987, L. Krieger 11307 (SP!) , 19 September 1989, H. O. Meni s.n. ( HUPG 1373 !) , 23 September 1989, M. R. Saad s.n. ( HUPG 1365 !) , 25 September 2003, M. R. B. do Carmo 256 (HUPG!) , 17 November 2003, M. R. B. do Carmo 416 (HUPG!) , 25 May 2010, R. S. Moro s.n. ( HUPG 16689 !) , 24 October 2009, R. S. Moro s.n. ( HUPG16267 !) , 5 November 2011, T. O. Tatiane s.n. ( HUPG 18274 !) , 9 September 2013, G. Curcio 1 (UPCB!) ; São Jerônimo da Serra , 27 September 1979, G. Hatschbach 24792 (MBM!, NY!, S online image, UPCB!, US online image); Tibagi , 9 June 1992, R. S. Moro 924 (HUPG!) , 07 August 1992, R. S. Moro 908 (HUM!) ; 07 August 1992, R. S. Moro 924 (HUM!) , 28 October 1992, A. C. Cervi s.n. ( HUPG 6235 !) , 28 October 1992, A. C. Cervi 3818 (UPCB!) , 6 November 1992, I. J. M. Takeda 949 (HUPG!) , 8 October 1994, L. Hiari. s.n. ( FUEL 14542 !) , 4 November 1994, C. A. Yamanaka s.n. ( FUEL 14134 !), 4 November, 1994, C. F. S. Ana 25 (FUEL!) , 4 November 1994, L. R. Pinto s.n. ( FUEL 17469 !) , 8 May 1996, R. C. Tardivo 182 (NY!) , 13 September 1996, C. K. Miyagi s.n. ( FUEL 28931 !, UB!) , 13 September 1996, D. Ohara s.n. ( FUEL 28929 !, UB!) , 13 September 1996, G. A. Berg s.n. ( FUEL 28934 !, FUEL 28935 !; HCF 17005!, UB!) , 18 September 1996, S. R. Ziller 1529 (MBM!) , 24 September 1996, A. L. S. Schütz 30 (EFC!) , 12 September 1997, F. N. Rodrigues s.n. ( FUEL 28921 !, UB!) , 18 September 2003, M. R. B. do Carmo 292 (HUPG!) , 27 October 2005, R. Goldenberg 823 (NY!) , 3 June 2006, G. Scharan s.n. ( HUPG 13932 !) , 3 June 2006, T. P. O. Pinto s.n. ( HUPG 11495 !) , 4 November 2011, F. R. Maia 5 (UPCB!) , 13 November 2011, R. Goldenberg 1666 (NY!, UPCB!) , 16 August 2012, C. J. Arruda 46 (IRAI!) , 6 July 2013, M. E. Engels 1152 (MBM!) , 6 July 2013, M. E. Engels 1153 (MBM!) , 18 May 2014, E. L. Siqueira 1055 (HCF!) , 2 May 2015, R. Gonçalves 17 (HUM!) , 3 June 2015, R. Gonçalves 52 (HUM!) ; Ventania, 19 October 2005, D. A. Estevan 1274 (FUEL!) . Rio Grande do Sul: Bom Jesus , 5 January 1947, B. Rambo 34687 (NY!, S online image) , 11 January 1987, D. B. Falkenberg 4194 (MBM!) , 11 January 1987, D. B. Falkenberg 4214 (ICN!, MBM!) ; Cambará do Sul , 20 December 1969, A. Ferreira s.n. ( ICN 7266 !) , 10 January 1971, K. Hagelund 6031 (ICN!) , 12 December 1978, J. Mattos 20112 (HAS!) , 2 January 1980, M. Sobral 100 (ICN!) , 14 December 1980, D. B. Falkenberg 112 (ICN!) , Caxias do Sul , 10 December 1979, M. Sobral s.n. ( ICN 50923!) , 20 January 1999, A. Kegler 88 ( US online image) , 12 January 2000, A Kegler 530 (FUEL!, US online image) , 5 December 2004, F. Marchett 111 ( US online image) ; 12 June 2013, J. Gaio 226 ( FURB online image, MBM!) ; Jaquirana, 10 December 2012, F. S. Meyer 1453 (UEC!, UPCB!) ; Mariana Pimentel, October 1982, M. Sobral 1150 (ICN!) , October 1982, M. Sobral 1163 (ICN!) ; Montenegro, 14 November 1986, I. Fernandes 238 (ICN!) , 14 November 1986, I. Fernandes 239 (ICN!) ; Osório, 20 November 1984, J. Mattos 26387 (HAS!) ; São Francisco de Paula , 2 January 1955, B. Rambo 56390 (HBR!) , 13 January 1956, B. Rambo 30844 ( S online image) , 6 January 1983, N. Silveira 23580 (HAS!) , 22 January 1983, s.c. ( ICN 59033!) , 9 March 1988, N. Silveira 6589 (HAS!) , 10 December 2000, R. Wasum 819 (MBM!, K!) , 23 November 2001, R. Wasum 1287 (G!, M!, NY!) , 23 November 2001, R. Wasum 1290 (FI!, G!, M!) , 4 November 2006, G. O. Romão 1909 (ESA!) , 27 May 2008, C. R. Buzzato 376 (ICN!) ; Sapucaia do Sul , 20 October 1986, I. Fernandes 208 (ICN!) ; Taquari, 2 December 1982, E. Franco s.n. ( ICN 59042!) , 2 November 1989, V. F. Nunes 496 (HAS!) ; Torres, 23 May 1981, M. L. Souza s.n. ( ICN 51902!); Vacaria , 9 December 2012, F. S. Meyer 1452 (UEC!, UPCB!) , 7 January 2016, F. S. Meyer 2163 (UPCB!) . Santa Catarina: undetermined municipality, February 1891, E. Ule 1749 (BR!, P!) , 5 December 1962, R. Klein 3228 ( US online image); Bom Jardim da Serra , 20 March 2009, F. Almeda 9880 (NY!) ; Campo Alegre, 18 October 1957, R. Reitz 5257 ( US online image) , 10 January 1958, R. Reitz 6155 ( US online image) , February 1967, L. B. Smith 10526 (NY!, US online image) , 5 December 1995, J. R. Stehmann 1713 (BHCB!) ; Garuva, 28 December 2013, F. S. Meyer 1786 (UPCB!) , F. S. Meyer 1787 (UEC!) , F. S. Meyer 1788 (UEC!) , F. S. Meyer 1789 (UPCB!) , F. S. Meyer 1790 (UPCB!) , F. S. Meyer 1792 (UPCB!) , F. S. Meyer 1793 (UPCB!) , F. S. Meyer 1794 (UPCB!) ; Lages, 16 December 1967, A. Lourteig 2257 (NY!, P!, S online image); Lauro Müller , 20 March 2009, F. Almeda 9880 (NY!) ; Mafra, 11 December 1962, R. Klein 3788 (NY!, US online image); São Bento do Sul , 20 August 2004, P. Schwirkowski 72 ( FLOR online image); São Joaquim , 16 January 1957, L. B. Smith 10172 (HBR!, NY!, US online image) , 17 January 1957, L. B. Smith 10226 ( US online image) , 3 January 1965, L. B. Smith 14198 ( US online image) , 6 January 1965, L. B. Smith 14358 (NY!, P!, US online image). São Paulo: Itapeva , 28 October 2008, R. Cielo-Filho 860 (SPSF!) , 27 November 2008, R. Cielo-Filho 811 (SPSF!) ; Itararé, 2 December 1989, J. Mattos 26809 (HAS!) , 1993, C. A. M. Scaramuzza s.n. ( ESA 63541!) , 26 November 1993, V. C. Souza 4671 (ESA!) , 27 November 1993, V. C. Souza 4699 (ESA!) , V. C. Souza 4779 (ESA!) , 13 November 1994, V. C. Souza 7189 (ESA!) , 20 October 2005, J. L. S. Tannus 928 (HUFU!) .

Distribuition and habitat:— Chaetogastra cogniauxiana is distributed in the states of Rio Grande do Sul (RS), Santa Catarina (SC), Paraná (PR), and São Paulo (SP; Figure 5 ), between 800–1,500 m elev. It occurs in highland grasslands (“Refúgio Vegetacional” according to the official classification of the Brazilian vegetation ( IBGE 2012), sometimes associated to open vegetation within the Araucaria forest (“Floresta Ombrófila Mista”, following IBGE 2012). It also occurs in grasslands associated to Cerrado [“Savana” following IBGE (2012)], such as “campo-sujo” and “campo-cerrado”, located mainly in northeastern Paraná and southeastern São Paulo.

Phenology:—Flowering and fruiting during the whole year, but with a peak between November and February.

Conservation status:— Chaetogastra cogniauxiana should be considered Vulnerable according to IUCN’s criterion A2c (2019).Although the Area of Occupancy is about 1,016.000 km 2, and the Extent of Occurence 173,680.579 km 2, with large populations and a reasonably wide extent of occurrence, its populations have been reduced. This reduction is happening because several occurrence sites have been turned into housing or industrial developments and rural properties. The most vulnerable populations in Paraná occur in the municipalities of Balsa Nova, Campo Largo and Piraquara, all part of the metropolitan region of Curitiba, the largest city in the state. The natural grasslands on the “Serra Geral” in the states of Rio Grande do Sul and Santa Catarina are frequently managed for livestock purposes. In São Paulo, the populations are also threatened by extensive transformation of natural landscapes into areas of agriculture and livestock raising, or even by extensive reforestation with exotic Pinus Linnaeus (1753: 1000) . Chaetogastra cogniauxiana has populations in protected areas, such as the “APA da Escarpa Devoniana” (PR), “APA Municipal do Rio Vermelho/Humboldt” (SC), “Parque Estadual de Campinhos” (PR), “Parque Estadual do Cerrado” (PR), “Parque Estadual do Guartelá” (PR), “Parque Estadual do Monge” (PR), “Parque Estadual de Vila Velha” (PR), “Parque Estadual da Serra do Tabuleiro” (SC), “Parque Estadual do Tainhas” (RS), “Parque Nacional de São Joaquim” (SC), “Parque Nacional de Aparados da Serra (SC/RS)”, “Parque Nacional da Serra Geral” (SC/RS), and “Floresta Nacional de São Francisco de Paula” (RS).

Etymology:—The epithet “ cogniauxiana ” honors one of the greatest specialists in taxonomy of Melastomataceae, Alfred Célestin Cogniaux (1841–1916), who previously recognized this entity as two varieties of C. gracilis .

Note:—Field observations and a detailed study of protologues and herbarium specimens led to the conclusion that two varieties of Tibouchina gracilis , T. gracilis var. gracilllima Cogniaux (1885: 387) and T. gracilis var. longisetosa Cogniaux (1885: 388) represent a single species that is distinct from C. gracilis . This conclusion implies an update on the flora of Brazil ( Goldenberg et al. 2020), especially in the states of Rio Grande do Sul ( Souza 1986), Santa Catarina ( Wurdack 1962), Paraná ( Meyer et al. 2010), and São Paulo ( Guimarães & Oliveira 2009). This does not mean that C. gracilis does not occur in these states, but that part of the specimens previously determined as C. gracilis actually belong to C. cogniauxiana . The names of either one of the two varieties of T. gracilis associated with this new species could be used for the assignment of a new taxonomic status and a consequent new combination, but we believe that neither one of the names would fit well in this new species. Therefore, we opted to choose to name it as a new species, based on article 11.2 of the International Nomenclature Code for algae, fungi, and plants ( Turland et al. 2018) which states that “a name has no priority outside the rank at which it is published”. Being this a new species (and not a new combination or status), we are not required to choose a type for C. cogniauxiana among the types of T. gracilis var. gracillima and T. gracilis var. longisetosa .

Affinities:— Chaetogastra cogniauxiana belongs to clade with species of Chaetogastra from South America and the West Indies, and it is positioned in a subclade distant from the one with C. gracilis ( Figure 6 ). Chaetogastra cogniauxiana seems to be most phylogenetically close to Chaetogastra herincquiana ( Cogniaux 1885: 399) Guimarães & Michelangeli (2019: 962) , and Chaetogastra hassleri ( Cogniaux 1904: 1276) Guimarães & Michelangeli (2019: 962) ( Meyer et al. 2021). A summary of the differences between C. cogniauxiana and closelly related species, i.e. the group of species with sympodial, poorly branched habit, and antesepalous stamens with a short pedoconnective (less than 1 mm) is presented in Table 1.

Chaetogastra cogniauxiana can be recognized by its sympodial, poorly branched habit, typical of the species in the former Tibouchina section Simplicicaules , being more similar to C. gracilis because of the elliptic-lanceolate or lanceolate leaves, these facing upwards, branches and hypanthium covered by dendritic trichomes, antesepalous stamens with a short pedoconnective (less than 1 mm in length). Chaetogastra cogniauxiana differs from C. gracilis by the characters pointed in the diagnosis. Many vegetative or floral structures are also smaller in C. cogniauxiana than in C. gracilis , although with some overlapping, such as the bracteoles 2.2–4.6 × 0.9–1.9 mm (vs. 2.8–6.2 × 1.1–2.9 mm), hypanthium 3.1–5 × 2.3–3.8 mm (vs. 4–6.7 × 3.3–4.3 mm), antepetalous filaments 4.2–5.7 mm long (vs. 4.9–6.7 mm long), antepetalous anthers 3.2–5 mm long (vs. 4.1–6 mm long), antesepalous filaments 5.4–7.5 mm long (vs. 5.8–9.4 mm long), and style 9.7–15.4 mm (vs. 11.4–17.4 mm). In C. cogniauxiana the anthers are always completely yellow ( Figure 2 A–B, D–G ) while in C. gracilis the anthers are more often yellow with purple to lilac spots, or sometimes completely purple ( Figure 1 A–E ), and less frequently totally yellow.

Chaetogastra cogniauxiana is similar to C. hassleri because of the elliptic-lanceolate or lanceolate leaves, these facing upwards, antesepalous stamens with a short pedoconnective (less than 1 mm in length). Chaetogastra cogniauxiana differs from C. hassleri mainly by the dendritic-hirsute, dendritic-setose, or dendritic-strigose branches and leaves (vs. lanose in C. hassleri ), and smaller petals, 9.8–13.4 × 8.8–9.1 mm (vs. larger petals, 19.3–24.1 × 15.1– 18.6 mm). Many vegetative or floral structures are also smaller in C. cogniauxiana than in C. hassleri , although with some overlapping or very close measures, such as the hypanthium 3.1–5 × 2.3–3.8 mm (vs. 4.7–6.8 × 3–5.4 mm in C. hassleri ), antepetalous filaments 4.2–5.7 mm long (vs. 5.9–6.1 mm long), antepetalous anthers 3.2–5 mm long (vs. 5.6–5.8 mm long), and ovary 3.6–4.4 × 2.5–3.2 mm (vs. ca. 5.2 × 3.6 mm). The anthers of C. cogniauxiana are always completely yellow, while in C. hasslerii the anthers are completely purple.

Chaetogastra cogniauxiana is also morphologically related with to C. cordeiroi , since both have a sympodial, poorly branched habit, elliptic-lanceolate or lanceolate leaves, these facing upwards, and branches and hypanthium covered by dendritic trichomes. Chaetogastra cogniauxiana differs from C. cordeiroi by the setose to strigose indument that covers the hypanthium ( Figure 2 C ; vs. sericeous in C. cordeiroi ) and also by the by the shorter pedoconnectives on the antesepalous stamens, 0.5–0.8 mm long (vs. 2.5–3.3 mm long).

The new species resembles Chaetogastra hieracioides Schrank & Martius ex De Candolle (1828: 133) due to the sympodial, poorly branched habit, the branches with internodes that can be quite long (3.9–10.8 cm long in C. cogniauxiana ), and yellow anthers in both stamen cycles. It differs from C. hieracioides by the number of leaf veins, with 3–5 (vs. 5–7 in C. hieracioides ), smaller bracteoles, 2.2–4.6 × 0.9–1.9 mm (vs. 4–4.5 × 1.8–2 mm), smaller hypanthium, 3.1–5 × 2.3–3.8 mm (vs. 7.5–8.7 × 3.3–4.1 mm), in addition to the antesepalous stamens with a smaller pedoconnective, 0.5–0.8 mm long (vs. 2–2.4 mm long).

It also resembles Chaetogastra minor Cogniaux (1885: 390) Guimarães & Michelangeli (2019: 964) due to the sympodial, poorly branched habit, and yellow anthers in both stamen cycles. It differs from C. minor because it lacks stolons with small leaves at the base of the plant (vs. present in C. minor ), elliptic–lanceolate or lanceolate leaves (vs. ovate), smaller bracteoles, 2.2–4.6 × 0.9–1.9 mm (vs. 4–6 × 1–1.5 mm), smaller hypanthium, 3.1–5 × 2.3–3.8 mm (vs. 7–7.5 × 3–3.5 mm), in addition to the antesepalous stamens with a smaller pedoconnective, 0.5–0.8 mm long (vs. 2–2.3 mm long).

Chaetogastra cogniauxiana resembles Chaetogastra rupestris Cogniaux (1891: 1176) Guimarães & Michelangeli (2019: 967) , due to the sympodial, poorly branched habit, hirsute branches, elliptic-lanceolate or lanceolate leaves. It differs from C. rupestris mainly by the antesepalous stamens with a short pedoconnective, 0.5–0.8 mm long (vs. 2.5–3.2 mm long in C. rupestris ), and a smaller filament, 5.4–7.5 mm long (vs. 8.2–8.9 mm long).

Finally, despite being positioned in the same subclade of C. herincquiana ( Meyer et al. 2021) , C. cogniauxiana shares few morphological features with it. Chaetogastra cogniauxiana is poorly branched (vs. more branched in C. herincquiana ), with elliptic-lanceolate or lanceolate leaves (vs. orbicular), slightly dimorphic stamens, the antesepalous with short, 0.5–0.8 mm long pedoconnectives (vs. quite dimorphic, the antesepalous stamens with elongated, 2.4–3.1 mm long pedoconnectives). Both can sometimes be sympatric, but C. cogniauxiana is more broadly distributed, and usually found in vegetation on well-developed soils, while C. herincquiana seems to prefer sandstone outcrops, and its distribution is restricted to a few locations in the Second Plateau of the state of Paraná, and southern São Paulo.

Chaetogastra cogniauxiana shows a wide morphological variation ( Figures 2 , 3 , and 4). Their specimens can vary considerably in relation to the type of indument covering the branches ( Figures 3 and 4 ), ranging from hirsute or setose (as the type of T. gracilis var. longisetosa ) to strigose (as the type of T. gracilis var. gracillima ); this variation may occur even in different specimens from the same population. Flowers can also vary widely in relation to the number of pieces, petals color ( Figure 2 ), and also the shape of the stamens ( Figures 3 H–I and 4 H–I ). Almost all specimens of C. cogniauxiana listed here were previously determined as C. gracilis in the herbaria, sometimes even with materials from both species mixed in the same sheet.

Chaetogastra cogniauxiana may occur sympatrically with populations of Chaetogastra cerastifolia ( Naudin 1850: 122) Guimarães & Michelangeli (2019: 958) , C. cordeiroi , Chaetogastra debilis Chamisso (1835: 499) , C. gracilis , C. hassleri , C. herincquiana , C. riograndensis Meyer & Goldenberg (2016: 253) , and C. rupestris .

Figures

FIGURE 1. Photos of living plants of Chaetogastra gracilis. A. Habit. B. Flower without petals, showing the sericeous indument that covers the hypanthium. C. Tetramerous flower with light pink petals. D. Pentamerous flower with pink petals. E. Pentamerous flower with purple petals. (A–E by Fabrício Schmitz Meyer).

FIGURE 2. Photos of living plants of Chaetogastra cogniauxiana. A. Habit, with inflorescence with tetramerous and pentamerous flowers, and light pink petals. B. Part of the inflorescence. C. Floral bud. D. Tetramerous flower with purple petals. E. Pentamerous flower with purple petals. F. Pentamerous flower with white petals. G. Hexamerous flower with purple petals. (A–E and G by Fabrício Schmitz Meyer; F by Mathias Enrich Engels).

FIGURE 3. Ink illustration of the holotype of Chaetogastra cogniauxiana. A. Branch. B. Leaf, with detail of the indument that covers the adaxial surface of the blade. C. Leaf, with detail of the indument that covers the abaxial surface of the blade. D. Dendritic trichomes that cover the branches and hypanthium. E. Bracteole, abaxial surface. F. Floral bud and bracteole. G. Hypanthium and sepals (adaxial surface) seen from a longitudinal section of the hypanthium. H. Antesepalous stamen. I. Antepetalous stamen. J. Gynoecium. (A–K: based on Goldenberg & Michelangeli 703 at UPCB).

FIGURE 4. Ink illustration of a paratype of Chaetogastra cogniauxiana. A 1. Lower portion of the plant, with detail of the indument that covers the branches. A 2.Top portion of the plant, showing the inflorescence. B. Leaf, with detail of the indument that covers the adaxial surface of the blade. C. Leaf, with detail of the indument that covers the abaxial surface of the blade. D. Dendritic trichomes that cover

FIGURE 5. Distribution map for Chaetogastra cogniauxiana (red circles) and partial distribuition of C. gracilis (green circles). Abbreviations: BA—Bahia, DF—Distrito Federal; ES—Espírito Santo; GO—Goiás; MG—Minas Gerais; MS—Mato Grosso do Sul, MT—Mato Grosso; PR—Paraná; RJ—Rio de Janeiro; RS—Rio Grande do Sul; SC—Santa Catarina; SP—São Paulo.

FIGURE 6. The position of Chaetogastra cogniauxiana in the phylogeny of Brachyotum and allies (Bayesian inference analysis based on sequences of six molecular markers:accD-psaI, nr-its,nr-ets,psbK-psbI, trnS-trnG, and waxy).A.Phylogenetic tree of tribe Melastomateae. B. Detail of the relatioships between the South American and Antillean species of Chaetogastra. Adapted from Meyer et al. (2021).