Pseudalbizzia Britton & Rose, N. Am. Fl. 23: 48. 1928.

Aviles Peraza, Gabriela, Koenen, Erik J. M., Riina, Ricarda, Hughes, Colin E., Ringelberg, Jens J., Carnevali Fernandez-Concha, German, Ramirez Morillo, Ivon Mercedes, Can Itza, Lilia Lorena, Tamayo-Cen, Ivan, Ramirez Prado, Jorge Humberto, Cornejo, Xavier, Mattapha, Sawai & Duno de Stefano, Rodrigo, 2022, Re-establishment of the genus Pseudalbizzia (Leguminosae, Caesalpinioideae, mimosoid clade): the New World species formerly placed in Albizia, PhytoKeys 205, pp. 371-400 : 371

Pseudalbizzia Britton & Rose, N. Am. Fl. 23: 48. 1928.

Type.

Pseudalbizzia berteroana Britton & Rose.

Arthrosamanea Britton & Rose, in Britton & Killip, Ann. New York Acad. Sci. 35: 128, 1936. Albizia section Arthrosamanea (Britton & Rose) Barneby & J.W. Grimes, Mem. New York Bot. Gard. 74(1): 206. 1996. Type: Arthrosamanea pistaciifolia Britton & Rose.

Description.

Unarmed trees with sympodial growth, up to 30 m, rarely small treelets of c. 3 m, microphyllidious to macrophyllidious; trunk 35-120(-150) cm dbh; young stems and all leaves and inflorescence-axes more or less densely tomentellous to pilosulous; stipules puberulent to glabrous, deltate, narrowly triangular, triangular-ovate, narrowly ovate, or narrowly lanceolate, veinless or faintly 3-veined, falling early to tardily, perhaps sometimes obsolete and/or lacking on mature leaves. Leaves bipinnate, not sensitive, (1-)2-15(-19) pairs of pinnae; leaflets (2-)16-52(-63) pairs per pinna; a nectary immediately below first pair of pinnae, near or well below mid-petiole, sometimes lacking or reduced to a minute pore, round, elliptic or vertically elongate, either shallow-cupular or almost plane, thick-rimmed, sometimes immersed in petiolar groove or even obsolete, much smaller nectaries at some distal pinnae, at the tip of most pinnae, and between 1-2 furthest pairs of leaflets; leaflets gently decrescent toward each end of the rachis or toward the base of the rachis or sub-equilong, the first pair of leaflets often reduced to paraphyllidia, sometimes minute, sometimes absent or perhaps falling early, the blades of the remaining leaflets elliptic, elliptic-ovate, oblong-elliptic, narrowly oblong-elliptic, lance-oblong to linear-lanceolate, base obliquely truncate to shallowly semi-cordate, apex deltately subacute, deltately acute to subacute, obtuse or apiculate, the larger ones (1.5-)2-4(-6) times as long as wide, margin strongly to slightly revolute; venation generally palmate, of 2-4(-5) veins from the pulvinule, the nearly straight main vein a little forwardly displaced and giving rise on each side to 2-13 major secondary veins, the inner of 2(-3) posterior primary veins incurved-ascending to anastomose slightly beyond mid-blade, the outer posterior vein and sometimes a faint anterior one very short and weak, all venation immersed on upper face. Inflorescence primary axis up to 30 cm long; peduncles (1-)2-8(-10) per node of the capitulate or corymbose-umbellate inflorescence, capitula 8-26(-40)-flowered; bracts heteromorphic or homomorphic, ovate, oblong-obovate or spatulate, linear-spatulate, falling early or persistent, sessile or shortly pedicellate, the flowers moderately to strongly dimorphic, the terminal ones generally longer. Flowers 5-merous, rarely 6-merous, glabrous to densely pubescent externally. Peripheral flowers: calyx campanulate, turbinate, turbinate-campanulate or narrowly campanulate, sessile or short pedicellate, lobes very short, depressed-deltate, ovate or triangular, glabrous or puberulent; corolla narrowly trumpet-shaped, erect or recurved, lobes ovate to lance-ovate; androecium with 9-30(-32) stamens, up to 20 mm long, united at the base forming a clear stemonozone, the staminal tube as long or longer than the stemonozone; ovary sessile or shortly stipitate, slenderly ellipsoid, conical at apex, glabrous or pubescent; style a little longer than the stamens, slightly dilated at the stigma. Terminal flowers: sessile or almost so, calyx shallowly campanulate to broadly campanulate, corolla tubular; androecium with 16-38(-42) stamens, 8.5-11.5(-13) mm long, united at the base forming a clear stemonozone, staminal tube equalling or longer than the stemonozone. Fruits solitary, or rarely 2-4 per capitulum, sessile, subsessile or cuneately contracted at base into a short pseudo-stipe, the body linear, linear-elliptic, narrowly elliptic-oblong, straight or nearly straight, sometimes decurved, plano-compressed, apex rounded but minutely apiculate to obtuse, (8-)13(-15)-seeded; valves papery, coriaceous, or grossly ligneous, olivaceous, castaneous, fuscous-greenish, or brown becoming tan-brown, closely transverse venulose, minutely puberulous, tomentulose, glabrescent to glabrous, framed by straight sutures or dilated, sometimes 3-angulate but not winged, transversely or horizontally, dehiscence tardy to very tardy, inert, through both sutures or dehiscence 0, in the latter, the pod crypto-lomentiform, incipiently lomentiform or lomentiform, then the whole fruit long persistent on the tree, commonly falling entire and breaking on the ground into 8-12 individually indehiscent segments, funicle apically sigmoid or ribbon-like (not sigmoid), lentiform; seeds obliquely ascending or straight, disciform, oblong-ellipsoid, elliptic, strongly compressed, the translucent, brownish or greyish testa produced as a peripheral wing, adherent to the embryo, which does not fill the testa-cavity, the pleurogram small, inversely U-shaped or U-shaped.

Notes.

The genus forms a group that is homogeneous in most respects, but diverse in the late developmental stages of the fruit, including: 1) fruit opening type: dehiscent, indehiscent, or irregularly breaking, 2) lateral shape: flat to conspicuously raised over the seed chambers, 3) texture and consistency of the valves: papery, chartaceous to woody ( Barneby and Grimes 1996). Figs 1 , 2 and 4 .

Pseudalbizzia (clade D) is the sister group of the Jupunba - Punjuba - Balizia - Hydrochorea clade (Fig. 3 ). Jupunba and Punjuba are markedly different morphologically, having spirally twisted dehiscent fruits with a red or ochre endocarp, reminiscent of the fruits of several other genera in tribe Ingeae (e.g., some Pithecellobium species, and some species of Archidendron F. Muell. and Cojoba Britton & Rose). The red or red-brown testa of the seeds of Jupunba and Punjuba are very distinctive, and are never black, and the embryo is nearly always aniline-blue due to the presence of delphinidin (an anthocyanidin). Punjuba is furthermore distinguished by its spicate inflorescences, which are not seen in Pseudalbizzia . Balizia has ligneous, indehiscent or tardily dehiscent pods, their seeds being released sometimes only after decay of the valves on the floor of terra firme forest, whereas in Hydrochorea the fruits are lomentiform, adapted to dispersal by water. The fruits of Hydrochorea recall some species of Pseudalbizzia adapted to similar riparian habitats. However, the species of Pseudalbizzia are markedly different in form of inflorescence, leaflet-venation, and shape of the ovary.

Two species previously placed in Albizia from the New World which were not included in our phylogenetic analysis, Albizia carbonaria and A. leonardii , have since been shown to be placed outside the New World Albizia clade ( Ringelberg et al. 2022; Koenen 2022b; Terra et al. 2022). Two other species, also not sampled here, nor by Ringelberg et al. (2022), are here tentatively included in Pseudalbizzia : Albizia barinensis L. Cárdenas and Albizia buntingii Barneby & J.W. Grimes (see below for discussion about the placement of these species). The genus Pseudalbizzia was published in the Flora of North America ( Britton and Rose 1928) and included just a single species, P. berteroana . The original description of Pseudalbizzia closely matches Albizia and no characters distinguishing the two genera were discussed by Britton and Rose (1928). The generic name Arthrosamanea was also published by Britton & Rose, again with a single species, A. pistaciifolia (Willd.) Britton & Rose, in an account of the Mimosaceae and Caesalpiniaceae of Colombia ( Britton and Killip 1936), but again no differences between the genus and Albizia or Pseudalbizzia were mentioned.

Pseudalbizzia as circumscribed here comprises 17 species and 5 varieties ranging in distribution from northwestern Mexico to northern Argentina and including the Greater Antilles (Figs 5 and 6 ). Full synonymy, detailed species descriptions, geographical distributions, representative samples of all species and keys for their identification can be found (under the name Albizia ) in Barneby and Grimes (1996), Linares (2005) and Rico Arce et al. (2008). Finally, we propose a new sectional classification of Pseudalbizzia to account for the non-monophyly of the series of Barneby and Grimes (1996), based on the phylogenies (Figs 3 and 4 ) which sampled nearly all species. A key to the sections is provided.

Figures

Figure 1. Morphology of Albizia s. l. showing selected members of the genera Albizia and Pseudalbizzia a-c Albizia ferruginea (Guill. & Perr.) Benth. in Congo a detail of leaf rachis and gland between terminal pinnae b detail of leaflets of a terminal pinna c seed and funiculus attached to the valve d Albizia glaberrima (Schumach. & Thonn.) Benth. in Malawi, detail of inflorescence e Albizia anthelmintica Brongn. in Malawi, habit f Albizia adianthifolia (Schumach.) W. Wight in Congo, habit g Albizia glaberrima in Malawi, branches and inflorescences h Albizia chinensis (Osbeck) Merr. in Thailand, inflorescences i Albizia odoratissima (L. f.) Benth. in Thailand, fruits j Albizia procera (Roxb.) Benth. in Thailand, fruits k Albizia splendens Miq. in Thailand, woody fruit l Pseudalbizzia multiflora var. multiflora in Ecuador, woody fruit m, n Pseudalbizzia pistaciifolia (Willd.) E. J. M Koenen & Duno in Ecuador m habit n woody fruit. Photos: a, b David J. Harris / With permission from RBG Edinburgh c Claude Boucher Chisale d-f Guenter Baumann g Jos Stevens h Natcha Sutjaritjai i-k Prateep Panyadee l-n Xavier Cornejo.

Figure 2. Habit, flower and fruit variation in the genus Pseudalbizzia a P. adinocephala pods (Hughes 1913) b P. coripatensis inflorescence (Hughes 2433) c P. coripatensis pods (Hughes 2433) d P. inundata pods (JRI Wood 26530) e P. multiflora habit (Hughes 2214) f P. multiflora leaves and pods (Hughes 2214) g P. pistaciifolia leaves and inflorescence (Cornejo 8426, GUAY) h P. niopoides habit (Hughes 419) i P. niopoides pods (Rivera 2245) j P. polycephala inflorescence (de Queiroz 15515) k P. tomentosa inflorescence (Hughes 1143) l P. sinaloensis pods (Hughes 1576) m P. tomentosa habit (Hughes 1335) n P. tomentosa pods (Hughes 1307). All photos by Colin Hughes except g, Xavier Cornejo.

Figure 3. Phylogeny of the ingoid clade (sensu Koenen et al. 2020), i. e., the traditionally recognized tribes Ingeae + Acaciaeae (excl. Vachellia). Phylogram derived from Bayesian analysis in MrBayes of the combined ETS and ITS data for Albizia and related genera. Main clades are labeled A-F (see text). Posterior support values are indicated above branches.

Figure 4. Phylogeny of the Jupunba clade redrawn from an ASTRAL species tree analysis by Soares et al. (2022) that utilizes data from Ringelberg et al. (2022) showing the evolutionary transitions from ancestrally papery, plano-compressed fruits to septate indehiscent fruits and subsequently to lomentiform hydrochorous fruits associated with species growing in seasonally inundated habitats in Pseudalbizzia and similar parallel transitions in Balizia and Hydrochorea. Photos of Pseudalbizzia inundata, P. multiflora, P. niopoides P. tomentosa and Balizia pedicellaris, by Colin Hughes, of Hydrochorea marginata, Jupunba barbouriana and J. leucophylla, by Erik Koenen.

Figure 5. Distribution map of Pseudalbizzia sections Paniculata, Pseudalbizzia, Uninervia and Pseudalbizzia buntingii (incertae sedis), as per the legend.

Figure 6. Distribution map of Pseudalbizzia sections Arthrosamanea and Pterocarpa, as per the legend.