Dioclea Kunth, Nov. Gen. Sp. (quarto ed.) 6: 437. 1823 [Sept. 1824].

Queiroz, Luciano Paganucci de & Snak, Cristiane, 2020, Revisiting the taxonomy of Dioclea and related genera (Leguminosae, Papilionoideae), with new generic circumscriptions, PhytoKeys 164, pp. 67-114 : 67

1. Dioclea Kunth, Nov. Gen. Sp. (quarto ed.) 6: 437. 1823 [Sept. 1824].

Hymenospron Spreng., Syst. Veg. [Sprengel] 4(2): 283. 1827. Type: Hymenospron apurense (Kunth) Spreng. [≡ Dioclea apurensis Kunth].

Dioclea Kunth sect. Dioclea [' Eudioclea '] in Benth., Comm. Legum. Gen. 2: 69. 1837.

Crepidotropis Walp., Linnaea 14: 296. 1840. Type: Crepidotropis brasiliensis Walp. [= Dioclea virgata (Rich.) Amshoff].

Dioclea Kunth subg. Dioclea in R.H. Maxwell, Novon 21(2): 227. 2011.

Dioclea Kunth ser. Dioclea in R.H. Maxwell, Novon 21(2): 227. 2011.

Dioclea ser. Virgatae R.H. Maxwell, Novon 21(2): 229. 2011. Type: Dioclea virgata (Rich.) Amshoff.

Type.

[lectotype, designated by Britton and Wilson (1924)]. Dioclea sericea Kunth.

Description.

Woody vines along forest edges, trailing or shrubby in open habitats. Stipules basifixed, not prolonged beyond their bases. Leaves pinnately trifoliolate, stipellate, leaf rachis short, mostly <5 mm long. Inflorescence an erect pseudoraceme, nodes multiflorous, woody, sessile, secundiflorous; bracteoles chartaceous or membranous. Flowers with calyx chartaceous, campanulate, the four lobes having almost the same length, upper lobe entire, triangulate, obtuse or acute, the other three lobes triangulate, acute, the lower lobe as long as the upper lobe; petals membranous, mostly purple, rarely withish-purple or reddish-purple, standard petal reflexed, ecallose, but slightly thickened near the base, provided with two basal and reflexed auricles, pubescent towards the apex on the outer surface, wing petals as long as the keel, oblong to obovate, provided with a basal spur on the upper margin, keel petals straight, elliptic to obovate, upper margin dentate, serrate or fimbriate; androecium pseudomonadelphous, the 10 stamens joined into a tube but the filament of the vexillary stamen free at the base, anthers monomorphic, all 10 stamens fertile; intrastaminal nectary disc entire, collar-shape; pistil sigmoid, ovary mostly 7-15-ovulate, stipitate, style not swollen. Fruits linear, mostly 5 × longer than wide, up to 2.5 cm wide, elastically dehiscent, the thin woody valves explosively twisting to release the seeds, upper margin straight and provided with a longitudinal rib or wing to each side of the suture. Seeds small, up to 14 mm long and 8 mm wide, lenticular (slightly biconvex); testa hard (bony), smooth, mostly mottled; hilum linear, encircling almost half of the seed’s circumference (Fig. 2G-K ).

Discussion.

Dioclea was described by Kunth (1823 [1824]) with two new species based on specimens collected by Humboldt and Bonpland: D. apurensis , from a depauperate fruiting specimen and D. sericea , with four flowering specimens and illustrated in plate 576. Dioclea sericea was selected as the type for the genus by Britton and Wilson (1924).

A few months after Kunth’s publication, Sprengel (1825) used the name Dioclea Spreng. for a genus of Boraginaceae . Later, Sprengel (1827) created the genus Hymenospron to which he transferred both of Kunth’s species, together with a species currently ascribed to Galactia [ G. rubra (Jacq.) Urb.]. Dioclea Spreng. is a later homonym in relation to Dioclea Kunth and thus illegitimate. Hymenospron Spreng. is a superfluous name with respect to Dioclea Kunth. The genus Crepidotropis was created by Walpers (1840) with just one species ( C. brasiliensis ) that is conspecific with Dioclea virgata (Rich.) Amshoff.

The genus Dioclea was named after Diocles of Carystus, a Greek philosopher from the 3rd century BC., probably because he associated the word ‘beans’ with the genus Dolichos L., which, in its original circumscription, included species now ascribed to Dioclea ( Candolle, 1825: 379-380).

Dioclea is diagnosed by the combination of flowers with a pseudomonadelphous androecium, standard petal reflexed and pubescent towards the apex, fruits with an oblong-linear, flat compressed body and explosive dehiscence and seeds elliptic-oblong, lenticular, with a long and linear hilum encircling about half of their circumference.

As circumscribed here, Dioclea includes 13 species from the tropical Americas, ranging from coastal central Mexico to northern Argentina and Paraguay. Dioclea virgata was introduced into the Old World and became a garden escape plant in Malaysia, Borneo and Ethiopia ( Maxwell 1969; Adema 1998).

Figures

Figure 2. Representatives of the clade A. Cleobulia coccinea (Mart. ex Benth.) L. P. Queiroz A flowering vine showing the arcuate inflorescences B detail of the inflorescence showing resupinate flowers; the inset highlights the wing petals (w) much shorter than the standard (s) and keel petals (k) C fruit (from Queiroz 16029). Cleobulia diocleoides Benth. D a resupinate flower showing the reduced wing (from Queiroz 16036). Cymbosema roseum Benth. E part of the inflorescence showing the bird pollinated flowers and the free adaxial stamen (arrow) F immature fruits showing the characteristic broad oblong fruit body and the long beak (from Cardoso 2868). Dioclea virgata (Rich.) Amshoff G flowers (from Cardoso 2374) H fruits (from Cardoso 2100). Dioclea fimbriata Huber I flowers (from Snak 1223). Dioclea burkartii R. H. Maxwell J a seed showing the marbled testa and the elongate hilum encircling about half of its circumpherence (arrow; from Snak 826). Dioclea apurensis K flowers (from Queiroz 13035). Photos A-D, J-K: L. P. Queiroz; E-H: D. Cardoso; I: C. Snak.