Magnolia sororum Seibert, Ann.

Vázquez-García, J. Antonio, Kelly, Daniel L., Mejía-Valdivieso, Darío A., Morales, Wilson, Dahua-Machoa, Alex, Vega-Rodríguez, Hermes, Peña, Alondra Salomé Ortega, Padilla-Lepe, Jesús & Muñiz-Castro, Miguel Á., 2022, Magnolia (Magnoliaceae) in Honduras: a synopsis with six new taxa, Phytotaxa 570 (2), pp. 109-149 : 136

Magnolia sororum Seibert, Ann. Missouri Bot. Gard. 25: 828–829. 1938 ( Figs. 18–20 )

Type:— PANAMA. Chiriqui: Valley of the upper Rio Chiriqui Viejo , 1800 m., Jul 1937 (fl, fr), G. & P. White 21 (holotype: MO!; isotypes: GH!, MO!) .

Magnolia sororum belongs to M. sect. Magnolia and differs from the other Central American species by being densely and generally fulvous-pubescent. Magnolia sororum is perhaps closely related to M. iltisiana and M. grandiflora in southeastern North America but differs from M. iltisiana in its fewer stamens, narrower perianth parts, smaller fruits and seeds and from M. grandiflora in its much smaller flowers and fruits and fewer carpels. It is immediately distinguishable from M. poasana ( Pittier 1910: 93) Dandy (1927: 263) by its pubescence, broader and longer inner perianth segments and a greater number of carpels, and from M. guatemalensis , which is nearly glabrous with cuspidate leaves and fewer carpels. It is most similar to M. yoroconte based on carpel numbers and the two spathaceous bracts that enclose the flower bud, but it may be easily distinguished by its dense pubescence and larger leaves and flowers. Two specimens from the Yoro Department, Perry 2664 (HJBL) and Perry et al. 101 (TEFH) from Cordillera Nombre De Dios and Locomapa, respectively, do not match any of the two subspecies of M. sororum and, thus, are here proposed as a new subspecies. The fruits and peduncles have similar yellowish pubescence as that of M. sororum subsp. lutea , but they possess smaller fruits with less numerous, non-beaked carpels and shorter peduncles. Based on the conspicuous differences in fruit size, number of carpels, pubescence colour and leaf shape, the species may be divided into three geographically disjunct subspecies as follows, only two of them present in Honduras:

Key to the subspecies of Magnolia sororum

1. Fruit 2.7–3.4 × 1.7–2.0, carpels 16–18(–20), mature peduncles 1.0- 1.5 cm ....................................... M. sororum subsp. oligocarpa

– Fruit 5.0–6.0 × 2.4–3.2 cm, carpels 32–45, mature peduncles 2.8–4.4 cm ........................................................................................2

2. Rusty brown pubescence on abaxial leaf surfaces, young branches, peduncles and (usually) polyfollicles, leaves mostly broadly elliptic to obovate ( Honduras, Nicaragua, Panamá)................................................................................ M. sororum subsp. sororum

– Pale yellow pubescence on the abaxial leaf surfaces, young branches, peduncles and (usually) polyfollicles, leaves narrowly elliptic to lanceolate ( Costa Rica; rare intermediates on Volcán Chiriquí, Panamá)..................................... M. sororum subsp. lutea

Figures

FIGURE 18. Magnolia sororum. Variability in specimens from Panamá: A. Leaves showing pubescent adaxial surface and pubescent flower bud, B. Arauz et al. B2620 (MO). B. Mature Fruit, S. Knapp. et al. 5981 (F). C. Developing fruit, from the type, Gene and Peggy White 21 (MO). D. Mature Fruit showing seeds, S. Knapp. et al. 5981 (MEXU). Photographs by A. Vázquez.

FIGURE 19. Magnolia sororum subsp. sororum from Olancho, Honduras, showing pubescent young fruit and leaves, Hawkins et al. 477 (BM). Photograph by A. Vázquez.

FIGURE 20. Magnolia sororum subsp. oligocarpa, type specimen (TEFH). Scanned by Lilian Ferrufino-Acosta.