Microlicia delicata R.B.Pacifico & Almeda, 2023

Pacifico, Ricardo, Almeda, Frank & Kriebel, Ricardo, 2023, Microlicia delicata and Microlicia pumila (Melastomataceae), two new species from unprotected mountains with campo rupestr vegetation in eastern Brazil, Phytotaxa 599 (4), pp. 207-224 : 211-215

Microlicia delicata R.B.Pacifico & Almeda , sp. nov. ( Figs. 2C , 3 ).

Type :— BRAZIL. Bahia: Piat „, Três Morros , Manoel Luiz , na Estrada para Inúbia, desvio à direita, 29 September 1998, fl., fr., H.P. Bautista 2897 (holotype: MBM [ MBM424042 ]!, isotypes: ASE, CAS!, HUEFS [ HUEFS0245039 ]!, HUEFS [ HUEFS0242283 ]!, HRB, HUFU [ HUFU00072462 ] image!, IPA, RB [ RB01358858 ]!, UFRN [ UFRN00024514 ] image!) .

Diagnosis:—Differs from Microlicia plumosa by its more delicate branches 0.5–1 mm wide (vs. 1.3–2 mm wide) with uppermost internodes evident (vs. not evident), shorter leaves 7.2–12.7 mm long (vs. 16.3–27.6 mm long) that are decussate but not cruciate when branches are seen from above (vs. cruciate), straight to somewhat recurved distally (vs. incurved distally), free from each other (vs. each leaf forming a narrow trough for most of its length such that it is snuggly nestled in the trough formed by the leaf below it), shorter calyx lobes 5.6–8.7 mm long (vs. 10.6–12.6), and petals 11–12 mm long (vs. 13–19 mm long).

Erect densely-branched shrubs ca. 70 cm tall. Upper cauline internodes 2–4.6 mm long, 0.5–1 mm wide, pale green (when dry) and defoliated with age, quadrangular, not sulcate, unwinged, appearing glabrous but beset with a few minute gland-tipped trichomes ca. 0.2 mm long clustered above the leaf scars; opposing internode faces on defoliated branches sulcate, the conspicuous adjoining leaf scars imparting a stepped appearance. Leaves decussate, not cruciate when branches are seen from above, concave-conduplicate (folded inwardly lengthwise), straight to somewhat recurved distally, free from each other, not concealing uppermost internodes (when dry), sessile, chartaceous, not glutinous, discolored, adaxial surface blackened with the marginal regions pale green, abaxial surface pale green (when dry); blades 7.2–12.7 × 0.6–0.8 mm, linear, apex terminating in a rigid eglandular trichome 0.6–1.2 mm long, base truncate, margins glandular-serrulate then becoming serrulate when the deciduous glands fall away, cilia 0.3–0.6 mm long, abaxial surface glabrous, adaxial surface appearing glabrous but covered with a few minute gland-tipped trichomes ca. 0.2 mm long along the middle region, leaf venation not evident. Flowers 5-merous on short pedicels 0.5–0.8 mm long, apical, solitary, ebracteolate. Hypanthia (at anthesis) 4–4.2 mm long, 2.7–3.1 mm wide at the torus, pale brown (when dry), obconical to cuneiform, equaling or surpassing the capsule in length at maturity, glabrous. Calyx tubes ca. 0.2 mm long. Calyx lobes 5.6–8.7 mm long (excluding apical trichome), 0.9–1.4 mm wide at the base, pale brown (when dry), narrowly-triangular, upper half conduplicate, apex terminating in a trichome 0.6–1.2 mm long, margins and indumentum like those of the leaves. Petals 11–12 × 5–6 mm, obovate, magenta, base attenuate, apex acute terminating in an eglandular trichome 0.8–1 mm long, both surfaces glabrous, margins entire and glabrous. Stamens 10, strongly dimetric and dimorphic; antesepalous (larger) stamens with filaments 3.5–3.8 mm long, glabrous, thecae (excluding rostra) 2.4–2.8 × 0.7–0.8 mm, oblong, smooth (tetrasporangiate), rostra 0.4–0.5 mm long, white, the ventrally inclined pores ca. 0.2 mm wide, nearly circular, pedoconnectives 5.7–6 mm long, appendages 0.9–1.3 mm long, apex rounded to truncate; antepetalous (smaller) stamens with filaments 2.9–3.3 mm long, glabrous, thecae (excluding rostra) 1.7– 1.8 × 0.4–0.5 mm, oblong, smooth (tetrasporangiate), rostra 0.2–0.3 mm long, white, the ventrally inclined pores ca. 0.15 mm wide, nearly circular, pedoconnectives 1.1–1.4 mm long, appendages 0.3–0.4 mm long, apex truncate to emarginate. Ovary (at anthesis) 2.5–2.7 × 1.2–1.5 mm, superior, subcylindrical, glabrous, 3-locular, not adnate to the hypanthium, carpels emarginated at the apex; style ca. 9 mm long, glabrous, stigma punctiform. Fruit at maturity an ovoid loculicidal capsule ca. 4.3–4.4 × 2.3–2.4 mm, pale brown, glabrous, 3-valvate, dehiscent from the apex to the base (basipetal), calyx lobes deciduous, enveloping hypanthia rupturing and flaking away with age, columellas deciduous. Seeds ca. 0.7 × 0.4 mm, yellow, oblong, testa foveolate, raphal zone nearly circular, ca. 40% the length of the seed.

Distribution, habitat and phenology:— Probably endemic to Três Morros in Piat„, Bahia, Brazil ( Fig. 4 ). It was collected in campo rupestre at about 1400 m elevation, flowering and fruiting in September.

Etymology:— The epithet refers to the delicate branches of this species.

Conservation status:— Microlicia delicata is known only from the type series. The type locality is outside all conservation units of the Chapada Diamantina. We suggest a conservation status of Data Deficient (DD).

Notes:— Microlicia delicata is apparently related to M. plumosa ( Fig. 4 A–D ) and Microlicia coronata ( Fig. 4E ). All of them share branches with leaf scars imparting a stepped appearance, sessile leaves that are more or less imbricate and linear to subulate, the leaf blades folded inwardly lengthwise, ciliate, terminating in a rigid eglandular trichome, magenta petals, and strongly dimetric and dimorphic stamens with tetrasporangiate thecae. Microlicia coronata can be readily distinguished by its branches lacking clusters of short trichomes above each node (vs. these present in M. delicata and M. plumosa ), hypanthia covered with gland-tipped trichomes 0.3–2 mm long that are stout at the base (vs. glabrous), calyx lobes subulate (vs. narrowly triangular), and a distribution restricted to Serra das Almas, Rio de Contas, Bahia.

Microlicia delicata is probably more closely related to M. plumosa , although it lacks the “feather-like” foliage that is typical of the latter ( Woodgyer & Zappi 2005, Fig. 5C ). Besides the differences mentioned in the diagnosis, M. plumosa has leaf cilia that are more yellowish and more inclined in relation the margin than in M. delicata . In M. plumosa , these cilia apparently have a mechanical function of holding each leaf nestled in the trough formed by the leaf below it ( Fig. 4C ). Diverse putative adaptations to xeric environments have been described in Microlicia ( Pacifico & Almeda 2022a), including a vegetative architecture that reduces excessive light absorption ( Pereira et al. 2018). In this context, the ecophysiological strategies associated with the leaf arrangement of M. plumosa deserve further investigation. The arrangement of the leaves on the branches of M. delicata is more similar to that found in M. coronata , i.e. leaves not cruciate when branches are seen from above, straight to somewhat recurved distally, and free from each other, with evident internodes on uppermost branches ( Fig. 4E ). Until recently, M. plumosa was known only from the type locality on the Pico do Barbado, Abaíra ( Woodgyer & Zappi 2005). A second population has recently been discovered at the Serra do Elefante, Abaíra (Pacifico et al. 652). Still, the distribution of M. plumosa is very restricted and mining activities are threatening the population at Serra do Elefante (R. Pacifico, pers. obs.). Microlicia delicata is probably allopatric with M. plumosa as it is known only from Três Morros, Piat„, where it also grows at lower elevations (around 1400 m; M. plumosa, 1900 –2033 m).

Figures

FIGURE 2. A–B. Comparative boxplots of leaf and calyx lobe length between Microlicia plumosa and M. delicata. A. Leaf length boxplot. B. Calyx lobe length boxplot. C–D. Photos of branches of M. delicata and M. plumosa, showing the general aspect of the foliage of each species when dry. C. Microlicia delicata (H.P. Bautista 2897). D. Microlicia plumosa (W. Ganev 2265).

FIGURE 3. Microlicia delicata. A. Habit. B. Cluster of trichomes above a node. C. Leaf in lateral view (left), abaxial view (middle) and adaxial view (right). D. Close up of a leaf in lateral view showing cilia on the margin. E. Detail of leaf trichome. F. Branchlet terminating in a flower. G. Antesepalous stamen. H. Antepetalous stamen. I. Capsule enveloped by the hypanthium, after calyx lobes fell away. J. Capsule. Voucher: Bautista 2897. Scale bars. A, 2 cm; B, D and E, 0.5 mm; C, G, H, I and J, 2 mm; F, 4 mm.

FIGURE 4. A. Map of Brazil with Bahia state highlighted in black. B. Bahia with distributions of Microlicia coronata, M. delicata, and M. plumosa. C. Satellite image of southwestern Chapada Diamanatina with distributions of M. coronata, M. delicata, and M. plumosa.

FIGURE 5. Photos of selected species compared to new taxa described in this study.A–D Microlicia plumosa. A. Population on the Pico do Barbado, Abaíra, Bahia, Brazil. B. Habit. C. Branchlet in lateral view, showing the “feather-like” foliage typical of this species. D. Branchlet in upper view showing the decussate cruciate leaf arrangement as seen from above. E. Microlicia coronata, fruiting branches. F. Microlicia naudiniana, flower close up (R. Pacifico et al. 403). G. Microlicia obovatifolia, flower close up (F.Almeda et al. 8899). Photos A–F by R. Pacifico, and G by F.Almeda.