Erythrophleeae 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 Erythrophleeae Legume Phylogeny Working Group, tribus nov.

Figs 98 , 99 , 100 , 101 , 102

Diagnosis.

Unarmed trees or treelets with macrophyllidious bipinnate leaves, alternate leaflets, flowers shortly pedicellate, densely packed in elongate spicate racemes, small, regular, with a short cupular hypanthium, sepals and petals ascending, almost erect. Similar to the genera Adenanthera L., Amblygonocarpus Harms and Tetrapleura Benth. ( Adenanthera clade, tribe Mimoseae ) in habit of unarmed trees with ample bipinnate leaves with alternate leaflets and small pedicellate flowers in spicate racemes, but differing by the ascending perianth giving a closed aspect to the flowers (vs. flowers open because sepals and petals are reflexed backwards) and seeds lacking a pleurogram. Also differentiated from Adenanthera by fruits straight or slightly curved with thick woody valves (vs. valves thin coriaceous and twisted after dehiscence) and from Amblygonocarpus and Tetrapleura by the fruits with flat valves [vs. tetragonal with a median rib ( Amblygonocarpus ) or wing ( Tetrapleura ) on each valve].

Type

(designated here). Erythrophleum Afzel. ex R. Br.

Included genera

(2). Erythrophleum Afzel. ex R. Br. (12 species), Pachyelasma Harms (1).

Description.

Unarmed trees or treelets; trunk with rough bark and a reddish sap when cut, brachyblasts absent. Stipules inconspicuous, mostly caducous. Leaves bipinnate, ample, macrophyllidious, with few pinnae and few leaflets per pinna, leaflets alternate, elliptical to oblong, frequently asymmetrical, pinnately veined. Inflorescences spicate racemes clustered in terminal or axillary panicles. Flowers perigynous, shortly pedicellate, 5-merous, bisexual, sepals and petals ascending, almost erect, the perianth almost cylindrical; stamens 10, free, the filaments glabrous or pubescent, anthers dehiscing through longitudinal slits; pollen in tricolporate monads; ovary stipitate, pluriovulate, style conical to cylindrical. Fruit dehiscent or, rarely, indehiscent, valves stiffly coriaceous or resinous, endocarp not septate nor breaking into one-seeded envelopes. Seeds slightly compressed, without pleurogram.

Clade-based definition.

The most inclusive crown clade containing Erythrophleum suaveolens (Guill. & Perr.) Brenan and Pachyelasma tessmannii (Harms) Harms, but not Campsiandra laurifolia Benth., Dimorphandra conjugata (Splitg.) Sandwith or Pentaclethra macrophylla Benth. (Fig. 98 ).

Distribution.

Tropical Africa (including Madagascar), eastern and south-eastern Asia and Australia.

Notes.

The new tribe Erythrophleeae is here proposed to include Erythrophleum and Pachyelasma , two genera which were previously included in the informal Dimorphandra group of old sense tribe Caesalpinieae (sensu Polhill and Vidal 1981). The two genera have been resolved as part of a grade subtending the mimosoid legumes (tribe Mimoseae ) in previous phylogenetic analyses using few molecular markers (e.g., Bruneau et al. 2001, 2008; Luckow et al. 2003; Bouchenak-Khelladi et al. 2010; Marazzi and Sanderson 2010; Manzanilla and Bruneau 2012), but rarely found to group together ( Herendeen et al. 2003a). Plastome genomic data also resolved Erythrophleum and Pachyelasma as successively diverging lineages subtending the Mimoseae ( Zhang et al. 2020). However, phylogenomic analyses of low copy nuclear genes have resolved the two genera together in a clade sister to the Mimoseae , but with each genus subtended by a long branch and with a short internode supporting the clade ( Koenen et al. 2020a; Ringelberg et al. 2022).

Erythrophleum and Pachyelasma share a combination of morphological traits only rarely found in non-Mimoseae Caesalpinioideae , such as bipinnate leaves and small pedicellate perigynous flowers clustered in dense spicate racemes. Structural extrafloral nectaries that were characterised as parenchymatous and elevated with a small domed structure with a central pore ( Pascal et al. 2000; Marazzi et al. 2019) are found in some species of Erythrophleum . Other than being rather cryptic, the presence of these extrafloral nectaries on the leaf rachis, combined with bipinnate leaves, are another morphological similarity with Mimoseae . The two genera also share a reddish sap and very toxic alkaloids and saponins. Erythrophleum is reported to be nodulating with fixation threads, as is typical of nodulating non-Mimoseae Caesalpinioideae ( Faria et al. 2022; status unknown for Pachyelasma ).

Figures

Figure 6. Generic relationships in tribe Ceratonieae. Left part of figure shows complete genus-level Caesalpinioideae phylogeny with the Ceratonieae indicated with a red rectangle. Branch lengths are expressed in coalescent units and terminal branches were assigned an arbitrary uniform length for visual clarity. Support for relationships is based on fractions of supporting and conflicting gene trees: pie charts show gene tree support and conflict per node (blue representing supporting gene trees, green gene trees supporting the most common alternative topology, red gene trees supporting further alternative topologies, grey gene trees uninformative for this node), and numbers above pie charts are Internode Certainty All support values [both calculated with PhyParts (Smith et al. 2015)]. If present, red numbers below pie charts are non-significant (i. e.> 0.05) outcomes of ASTRAL's polytomy test (Sayyari and Mirarab 2018), which tests for each node whether the polytomy null model can be rejected. Monophyletic genera are represented by single branches; see Suppl. material 2 for a phylogeny with all accessions. See Suppl. material 3 for gene tree support across the phylogeny. The phylogeny is a pruned version of the backbone phylogeny of Ringelberg et al. (2023), where full details of the data and phylogenomic analysis methods are presented.

Figure 98. Generic membership and phylogenetic position of tribe Erythrophleeae. For description of phylogeny and support values, see Fig. 6 caption (page 63).

Figure 99. Habit, bark and foliage of Erythrophleeae A Erythrophleum fordii Oliv. at Hung Temple, Vietnam B bark of Erythrophleum couminga Baill. in Madagascar C Pachyelasma tessmannii (Harms) Harms in Congolian rainforest D, E, H Erythrophleum chlorostachys Baill. D rugous bark E tree in northern Australian savannas H foliage F Erythrophleum lasianthum Corbishley foliage G Erythrophleum suaveolens (Guill. & Perr.) Brenan foliage and terminal inflorescences, Ntumbachusi falls, Zambia. Photo credits A Hungda (https: // tropical. theferns. info / image. php? id = Erythrophleum + fordii) B Solofo Eric Rakotoarisoa, iNaturalist (https: // www. inaturalist. org / photos / 42581094) C Bart Wursten (https: // www. flickr. com / photos / zimbart / 8212743587 / in / photolist-dvJsxn-dvJnwi) D, E, H G Mahajan (https: // alchetron. com / Erythrophleum-chlorostachys) F JMK (https: // wikiwand. com / en / Erythrophleum _ lasianthum) G MG Bingham (https: // malawiflora. com / speciesdata / image-display. php? species _ id = 126540 & image _ id = 8).

Figure 100. Distribution of Erythrophleum based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.

Figure 101. Tribe Erythrophleeae inflorescences, fruits and seeds A-D Spicate racemes of species of Erythrophleum with small flowers, erect sepals and petals and hairy stamen filaments A E. suaveolens (Guill. & Perr.) Brenan with a visiting fly B E. chlorostachys (F. Muell.) Baill. (Ironwood) C, D E. lasianthum Corbishley E-I Fruits and seeds E dehisced fruits of Erythrophleum suaveolens F, G ripe fruits of Erythrophleum lasianthum H, I dispersed fruits of Pachyelasma tessmannii (Harms) Harms on the forest floor, showing the flat valves and raised margins. Photo credits: A AlkalIn (https: // commons. wikimedia. org / wiki / File: Flowers _ of _ Erythrophleum _ suaveolens. jpg) B T Harley (https: // territorynativeplants. com. au / erythrophleum-chlorostachys-ironwood) C, D SAplants E Oliver Haumann, iNaturalist (https: // www. inaturalist. org / photos / 60428121) F, G JMK (https: // commons. wikimedia. org / wiki / File: Erythrophleum _ lasianthum, _ loof _ en _ peule, _ Manie _ van _ der _ Schijff _ BT, _ a. jpg) H B Wursten (https: // flickr. com / photos / zimbart / 8212726705) I T Stevart (https: // tropicos. org / ImageDownload. aspx? imageid = 100336252).

Figure 102. Distribution of Pachyelasma based on quality-controlled digitised herbarium records. See Suppl. material 1 for the source of occurrence data.