Trembleya s.s. clade of Microlicia

Pacifico, Ricardo, Almeda, Frank, Penneys, Darin S. & Fidanza, Karina, 2022, Systematics of the Trembleya sensu stricto clade of Microlicia (Melastomataceae, Lavoisiereae), PhytoKeys 216, pp. 1-101 : 1

Trembleya s.s. clade of Microlicia

Diagnosis.

Perennial shrubs or treelets. Leaves petiolate, not imbricate, not keeled, the adaxial surface glandular-punctate to glabrescent, venation basal acrodromous, impressed on the adaxial surface and prominent on the abaxial surface, consisting of amphicribral or bicollateral vascular bundles. Flowers usually 5-merous, diplostemonous, pedicellate, subtended by a pair of bracteoles. Hypanthia not fused to the ovary, lacking a crown of trichomes at the apex. Stamens strongly dimorphic or subisomorphic, anthers 2-celled, tetrasporagiate. Ovaries superior, (3-4-)5-locular. Capsules dehiscent from the apex to the base, columella deciduous.

Description.

Perennial erect shrubs or small trees (0.1-)0.3-4 m tall, woody, sometimes densely branched. Distal branches quadrangular, usually light green (when fresh) and glutinous, glandular-punctate, sometimes granulose or pruinose, eventually covered with eglandular or gland-tipped trichomes, internodes 0.1-4.5 cm long, angles unwinged or narrowly winged, nodes thickened. Old branches terete, brownish and defoliating towards the base. Leaves decussate, petiolate, not imbricate, not keeled, papyraceous, chartaceaous or coriaceous, usually discoloured when dry. Petioles 0.3-17 mm long. Blades 0.4-11.7 cm long, 0.05-5 cm wide, oblong, lanceolate, elliptic, narrowly elliptic, ovate or linear, entire to slightly serrulate, sometimes entire along the basal half and serrulate on the upper half, rarely ciliate, lacking support tissue on the leaf margin. Adaxial surface green (when fresh), becoming pale green, pale brown, or darkened (when dry), glutinuous, glandular-punctate to glabrescent, glandular trichomes (when present) appearing sessile (i.e. on peduncles too short to be seen with a 40 × magnification stereoscope). Abaxial surface usually green (when fresh), becoming pale green (when dry), always lighter than the adaxial surface, glandular-punctate to covered with eglandular or gland-tipped trichomes, or totally concealed by a lanose indumentum. Venation composed of 1-7 basal acrodromous veins, mid-vein stout, lateral veins becoming faint towards the leaf margin, impressed on the adaxial surface and prominent on the abaxial surface, consisting of amphicribral or bicollateral vascular bundles, tertiaries usually evident, nearly perpendicular to the mid-vein and branching towards the leaf margin. Inflorescences simple or compound dichasia, consisting of biparous cymes throughout or proximally biparous and distally uniparous cymes or reduced to solitary flowers on the apical region of the branches. Inflorescence bracts 0.7-5.0 cm long, 0.1-2.0 cm wide, petiolate, usually similar to the principal leaves in shape and indumentum, 1-5-nerved from the base. Bracteoles sessile or with petioles up to 6 mm long, blades 2.2-11 mm long, 0.5-5.5 mm wide, linear, elliptic, lanceolate, ovate, narrowly elliptic, oblong or oblanceolate, 1-3(-5)-nerved from the base, entire to slightly serrulate, rarely ciliate, usually differing in shape, but similar in indumentum to the principal leaves. Flowers (4-)5(-6)-merous, diplostemonous, pedicellate, subtended by a pair of bracteoles. Hypanthia 1.7-6.5 mm long, 1.5-5.2 mm wide at the torus, campanulate to urceolate, not fused to the ovary, externally glandular-punctate, sometimes covered with eglandular or gland-tipped trichomes, rarely completely concealed by a lanose indumentum, lacking a crown of trichomes at the apex. Calyx tubes 0.1-1.2 mm long, externally like the hypanthia. Calyx lobes 0.7-9.7 mm long, 0.4-3.2 mm wide at the base, oblong, triangular, narrowly triangular or subulate, entire or rarely sparsely ciliate, apex acute to acuminate, rarely terminating in an apical eglandular trichome, similar to the hypanthia in indumentum. Petals 4.5-26 mm long, 2.4-15 mm wide, obovate, entire, eventually ciliate, white, magenta or yellow (when fresh), apex acute, rounded, acuminate or emarginate, both surfaces glabrous or rarely sparsely glandular-punctate on the adaxial surface. Stamens (8)10(12), strongly dimorphic or subisomorphic, glabrous throughout, filaments linear, white, pink or yellow, pedoconnectives well-developed, anthers oblong, 2-celled (tetrasporangiate), rostrate, apical pores circular and ventrally inclined. Larger (antesepalous) stamens (4-)5(-6), filaments 1.5-6.3 mm long, pedoconnectives 1.3-7.3 mm long, ventral appendages 0.1-3.0 mm long, the apex usually emarginate to bilobate, thecae (excluding rostra) 0.8-3.8 mm long, purple, red, vinaceous or rarely yellow, rostra 0.2-0.7 mm long, pores 0.1-0.3 mm wide. Smaller (antepetalous) stamens (4-)5(-6), filaments 1.5-5.4 mm long, pedoconnectives 0.2-1.9 mm long, ventral appendages usually up to 0.1 mm long, apex truncate to emarginate, thecae (excluding rostra) 0.8-3.2 mm long, yellow to orange, rostra 0.2-0.6 mm long, pores ca. 0.2 mm wide. Ovaries 0.9-4.1 mm long, 0.7-3.1 mm wide, ovoid, cylindrical or globose, superior, (3-4-)5-locular, glabrous. Styles 3-10 mm long, filiform, sigmoid to incurved, white, pink or yellow, glabrous, stigmas punctiform. Capsules loculicidal, 2.3-8.0 mm long, 2.3-6.0 mm wide, ovoid or globose, the torus initially constricted at the apex, dehiscent from the apex to the base, columella deciduous. Fruiting calyx tubes 0.2-3.1 mm long. Fruiting calyx lobes 1.2-11.5 mm long, rarely thickened. Seeds 0.3-0.9 mm long, reniform, the testa foveolate-reticulate.

Nomenclatural notes

Based on collections housed in the herbarium at Paris (P), Martin and Cremers (2007) selected types for Melastomataceae described by Charles Victor Naudin (1815-1889), including six names for taxa that are part of the Trembleya s.s. clade ( Microlicia calycina , M. paniculata , M. pentagona , M. stenophylla , M. trembleyiformis and M. tridentata ). More than one specimen corresponding to the types cited by Martin and Cremers (2007) were found at P for the six names. These type citations were here treated as first-step lectotypifications. Thus, second-step lectotypes were designated in these cases following Article 9.17 of the Shenzhen Code ( Turland et al. 2018). Overall, our nomenclatural update of this clade includes the designation of 34 lectotypes for names at specific and infraspecific ranks and 25 new synonyms.