Pterogyneae Legume Phylogeny Working Group, tribus nov.

Bruneau, Anne, de Queiroz, Luciano Paganucci, Ringelberg, Jens J., Borges, Leonardo M., Bortoluzzi, Roseli Lopes da Costa, Brown, Gillian K., Cardoso, Domingos B. O. S., Clark, Ruth P., Conceicao, Adilva de Souza, Cota, Matheus Martins Teixeira, Demeulenaere, Else, de Stefano, Rodrigo Duno, Ebinger, John E., Ferm, Julia, Fonseca-Cortes, Andres, Gagnon, Edeline, Grether, Rosaura, Guerra, Ethiene, Haston, Elspeth, Herendeen, Patrick S., Hernandez, Hector M., Hopkins, Helen C. F., Huamantupa-Chuquimaco, Isau, Hughes, Colin E., Ickert-Bond, Stefanie M., Iganci, Joao, Koenen, Erik J. M., Lewis, Gwilym P., de Lima, Haroldo Cavalcante, de Lima, Alexandre Gibau, Luckow, Melissa, Marazzi, Brigitte, Maslin, Bruce R., Morales, Matias, Morim, Marli Pires, Murphy, Daniel J., O'Donnell, Shawn A., Oliveira, Filipe Gomes, Oliveira, Ana Carla da Silva, Rando, Juliana Gastaldello, Ribeiro, Petala Gomes, Ribeiro, Carolina Lima, Santos, Felipe da Silva, Seigler, David S., da Silva, Guilherme Sousa, Simon, Marcelo F., Soares, Marcos Vinicius Batista & Terra, Vanessa, 2024, Advances in Legume Systematics 14. Classification of Caesalpinioideae. Part 2: Higher-level classification, PhytoKeys 240, pp. 1-552 : 1

Tribe Pterogyneae Legume Phylogeny Working Group, tribus nov.

Figs 18 , 19 , 20

Diagnosis.

Differing from all other tribes of subfamily Caesalpinioideae by the combination of imparipinnate leaves with a well-formed rachis extension, alternate leaflets, compact catkin-like racemes, flowers small, polygamous and regular, the ovary with a marginal wing, style subterminal, fruit a samara with the basal seed chamber with a small subterminal beak (style remnant), and chromosome number 2 n = 20.

Type.

Pterogyne Tul. (designated here).

Included genera.

Tribe Pterogyneae includes only the genus Pterogyne with one species.

Clade-based definition.

The most inclusive crown clade containing Pterogyne nitens Tul., but not Ceratonia siliqua L., Umtiza listeriana Sim or Cassia fistula L.

Notes.

The tribe Pterogyneae is being proposed here to include the single genus Pterogyne . This genus was previously ascribed to the tribe Cynometreae (currently subfamily Detarioideae ) by Bentham (1865) and Taubert (1894). Later, it was recognised as morphologically distinct and placed in the phenetically isolated Pterogyne group within the broadly polymorphic and polyphyletic tribe Caesalpinieae (sensu Polhill and Vidal 1981; Lewis 2005b). This isolated position was also demonstrated by phylogenetic analyses using different morphological and molecular markers, in which Pterogyne is resolved in quite different positions in the Caesalpinioideae phylogeny (Fig. 18 ). Most plastid sequence data support a position of Pterogyne as sister to the Caesalpinieae ( Caesalpinia clade in Bruneau et al. 2001, 2008; Fig. 18C ), whereas combined analyses of plastid and morphological data ( Herendeen et al. 2003a) and the nuclear sucrose synthase (SUSY) gene ( Manzanilla and Bruneau 2012) suggest a closer relationship with the Cassieae (Fig. 18B ). More recent analyses of the entire plastid genome of the Leguminosae also provided ambiguous results and found Pterogyne to cluster with the Caesalpinieae when considering only the coding genes (Fig. 18C ) and sister to all remaining Caesalpinioideae when considering the non-coding loci (Fig. 18D ; Zhang et al. 2020). Phylogenomic analyses of ca. 1500 nuclear genes supported Pterogyne as sister to all Caesalpinioideae , except the Ceratonieae and Gleditisieae clades (Fig. 18A ; Zhao et al. 2021; Kates et al. 2024).

The uncertain phylogenetic position of Pterogyne probably reflects the short diversification time between the divergence of the four distinct lineages, Pterogyne , Cassieae , Caesalpinieae , and the remaining Caesalpinioideae , in the Paleocene, with Pterogyne representing a long branch diverging from those other lineages between 57 Ma and 60 Ma ( Zhao et al. 2021).

The recognition of the monogeneric (and monospecific) tribe Pterogyneae is additionally supported by its unique combination of morphological features, as highlighted in the diagnosis above. This isolated evolutionary position is also corroborated by a chromosome number of 2 n = 20 for Pterogyne nitens , which is cytologically unique in subfamily Caesalpinioideae ( Goldblatt 1981b).

Figures

Figure 18. Contrasting phylogenetic positions for Pterogyne as supported by different analyses A sister to all Caesalpinioideae, except Ceratonieae and Gleditsiae (ca. 1500 nuclear genes; Zhao et al. 2021) B sister to Cassieae (SUSY nuclear gene and combined trnL intron + morphological data; Manzanilla and Brunau 2012, Herendeen et al. 2003 a, respectively) C sister to Caesalpinieae (trnL intron and coding plastid genes; Bruneau et al. 2001; Zhang et al. 2020) D sister to the remaining Caesalpinioideae (plastid non-coding loci; Zhang et al. 2020).

Figure 19. Pterogyne nitens Tul., the only species of tribe Pterogyneae A cultivated tree in Brasilia (Brazil) B flowering branch showing the foliage and inflorescences; note the alternate leaflets; the insets show an expanding leaf (left) highlighting the tiny caducous stipules (arrow) and a stipel at the leaflet attachment (right) C inflorescences with a visiting Syrphidae fly (Diptera) D part of the spicate raceme with some flowers removed E close-up of flowers F samaras, the inset showing the subterminal style remnant at the top of the seed chamber (arrows) G samara seed chamber opened to show the seed. Photo credits A-G RT Queiroz https: // rubens-plantasdobrasil. blogspot. com /.

Figure 20. Distribution of Pterogyne based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.