Mysanthus

Taxonomy

Mysanthus G.P. Lewis & A. Delgado Salinas Kew Bull. 49(2): 343. 1994.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.72A.
Tribe: Phaseoleae.
Subtribe: Phaseolinae.
Species Studied - Species in Genus: 1 studied; 1 in genus.

Description

Fruit: A legume; unilocular; 4.8–6.5 cm long (from literature); 0.8–1(–1.4) cm wide (from literature); ca. 0.5 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; without orifice formed by curving of fruit or fruit segments; slightly curved; not plicate; not twisted; asymmetrical; falcate; with both sutures parallelly curved; not inflated; compressed; without beak; tapered at apex; aligned with longitudinal axis of fruit; rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin embellished; margin with thickened sutural areas; wing(s) absent; nonstipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves twisting. Replum invisible. Epicarp dull; monochrome; green to tan (yellowish); with surface texture uniform; glabrate to pubescent and indurate; with hairs erect; with 1 type of pubescence; puberulent; with pubescence white; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; slightly, veined; reticulately veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; white; smooth; without adhering pieces of testa; septate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; exfoliating in part; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 5–8 (from literature); length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus ca. 1 mm long; of 1 length only; flattened; straight. Aril present; dry; when dry rim-aril and tongue-aril; entire; tan.

Seed: 5–7 mm long; 3.5–5 mm wide; 2–2.5 mm thick; not overgrown; not angular; symmetrical; elliptic to reniform; compressed; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy to dull; not modified by a bloom; colored; mottled; with frequent mottles; reddish brown to tan; with black overlay; glabrous; smooth; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed; concealed by aril; without faboid split; larger than punctiform; 1.5–2 mm long; with curved outline; oval; apical according to radicle tip but marginal according to seed length; flush; within rim; rim color of testa. Lens discernible; 0.7–1 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; mounded; similar color as testa; darker than testa; brown, or tan; within rim; rim color of testa. Endosperm absent. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; notched at radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; white; inner face flat; glabrous on inner face. Embryonic axis right angled; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip curved; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule well developed; glabrous.

Distribution

Brazil in the states of Bahia and SSo Paulo.

New World; South America.

Generic Notes

Mysanthus was segregated from Phaseolus (10.72) by Lewis and Delgado (1994). Its position in subtribe Phaseolinae is uncertain (Lewis and Delgado Salinas, 1994). Data from the single sample studied was supplemented from their description.

Tribal Notes

Tribe Phaseoleae

Bruneau et al. (1995) carried out cladistic analyses of tribe Phaseoleae using chloroplast DNA restriction site data. Their results indicated that the tribe is not monophyletic and that the tribal delimitations between Phaseoleae and Desmodieae (11) and between Phaseoleae and Millettieae (7) are problematic.