Lavoisiera chamaepitys A. Saint-Hilaire ex Naudin (1844: 153)

Martins, Angela B. & Almeda, Frank, 2017, A Monograph of the Brazilian endemic genus Lavoisiera (Melastomataceae: Microlicieae), Phytotaxa 315 (1), pp. 448-450 : 448-450

9. Lavoisiera chamaepitys A. Saint-Hilaire ex Naudin (1844: 153) . Type:— BRAZIL. Minas Gerais: “In pascuis arenosis prope fodinas adamantium vulgo Serviço do Rio Pardo, in tractu dicto Distrito dos Diamantes e prope Córrego Novo in montibus Serra de Curmatahy in prov. Minas Geraes,” A. F. C. P de Saint-Hilaire s.n. (lectotype, here designated: P!) .

Erect, rigid, compactly to laxly and dichotomously branched, occasionally subfastigiate or sometimes cespitose subshrubs 0.3–0.5(–1.2) m tall, perennating from a lignotuber, glabrous throughout. Branches and branchlets rigid, subquadrangular to subrounded, longitudinally furrowed on opposite sides, defoliating basally with age; internodes 0.5–1(–2) mm long, with knobby thickenings that persist where a leaf has fallen away; nodes with conspicuous leaf scars and beset with short, inconspicuous glandular trichomes. Leaves sessile, semi-amplexicaul, densely erectimbricate, concealing the short internodes when fresh, spreading to suberect and flaring outward at the apex when dry; blade 6–7(–11) × 1.5–2 mm, firmly chartaceous to rigid-coriaceous, linear-triangular to subulate and distinctly concave adaxially, base enlarged, subrounded, apex sharp and pungent, margin entire, glabrous, subcallose and sometimes reddish, somewhat but not prominently keeled, yellowish-green to dark green on both surfaces, 1- nerved. Flowers 5–6-merous, solitary and terminal on the branchlets but becoming central by the growing of lateral branches, sessile. Bracts subtending the flowers 4–6, sessile, blade 7–8 × 3–4 mm, subobovate, base rounded, apex long cuspidate-apiculate (3–4 mm long), margin callose, inconspicuously crenulate, sometimes irregularly erose or lacerate, flushed with red, otherwise similar to the principal leaves. Hypanthium (at anthesis) 3–4 × 3 mm, campanulate to subcylindric, green, glabrous. Calyx tube inconspicuous to ca. 0.5 mm long; calyx lobes (at anthesis) 5–6 × 2–3 mm, membranaceous to chartaceous, triangular to oblong-triangular, apiculate at the apex, margins entire or inconspicuously and sparsely glandular-ciliolate, otherwise glabrous on abaxial surface and glabrous to sparingly glandular puberulent adaxially, tardily caducous. Petals 13(–20) × 7(–10) mm, pink to

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MARTINS & ALMEDA lavender with a yellow-green band at the base, obovate, apex truncate and asymmetrically apiculate, base attenuate, margin entire, eciliate or minutely and sparsely glandular-ciliolate. Stamens 10 or 12, dimorphic; large (antesepalous) stamens 5–6, filaments 6–7 mm long, anther thecae 3.5 × 0.8–1 mm, yellow but often becoming brownish following pollination, linear-oblong, rostrum ca. 0.5 mm long, white, pedoconnective 5–6 mm long, appendage ca. 1.5 mm long, rounded to obscurely bilobed, yellow; small (antepetalous) stamens 5–6, filaments 5 mm long, anther thecae 2.5 × 0.7 mm, yellow, linear-oblong, rostrum ca. 0.5 mm long, white, pedoconnective 0.6–1 mm long, appendage 0.5–1 mm long, rounded to obscurely bilobed. Ovary 2- or 4–5-locular, 1/2 to 3/4 inferior, style 6–7 mm long, glabrous, curved apically, stigma punctiform. Fruiting hypanthium (including calyx lobes) ca. 10 mm long, slightly constricted above the ovary. Capsule (at maturity) 5 mm long, globose to urceolate, coriaceous, enveloped by the persistent hypanthium, dehiscing from the base to the apex, brown. Seeds 0.82–0.98 × 0.47–0.56 mm, oblong or oblong-angulate, dark brown, periclinal cell walls of the testa concave (foveolate), the raphal zone about 30% the length of the seed. Chromosome number unknown.

Illustrations:— Figure 29 ; Cogniaux (1883: t. 37).

Photographic images:— Figures 1J, K ; 6E, F .

Phenology:—Flowering April and June through November; fruiting in April, June, and August.

Distribution and habitat:—Endemic to Minas Gerais where it is largely restricted to a limited area of the Cadeia do Espinhaço on the Diamantina plateau with an outlying population in the Grão Mogol area in campo rupestre and campo úmido at 600–1416 m. Figure 28 .

Conservation status:— This local and uncommon species is known from 17 collections (including the type). The EOO is 21 km ² and the AOO is 16 km ². At least three populations are afforded some protection in Parque Estadual da Grão Mogol , Parque Estadual do Biribiri , and Parque Estadual do Rio Preto respectively. Periodic fires are the major threat in its campo rupestre habitat. We recommend a classification of Critically Endangered ( CR): B1 b(iii)c(iv) .

Discussion:— Lavoisiera chamaepitys is a striking plant with unusual vegetative morphology. Its glabrous leaves are linear-triangular to subulate, 1-nerved, densely imbricate, and tightly appressed to the stems when fresh but recurved-spreading when dry ( Figures 29A, B ). The tight imbricate posture of the adaxially concave leaves and short cauline internodes creates an effect that is almost conifer-like. Lavoisiera chamaepitys is not likely to be confused with its congeners based on these vegetative features together with its sessile 5–6-merous flowers, pink petals with a conspicuous yellow-green band at the base, and glabrous hypanthia and calyx lobes.

In the protologue, Naudin describes the ovary of this species as 4–5-locular but Cogniaux (1883) subsequently described the ovary as 2-locular and his illustration also depicts it as such. We previously doubted the occurrence of 2-locular ovaries in Lavoisiera ( Almeda & Martins 2001) . Based on a more extensive study of some of the lessercollected species it is now clear that 2-locular ovaries can be found in some populations of L. chamaepitys , some specimens of L. scaberula , and in the newly described L. minima . We have found some geographically correlated differences with respect to ovary locule number in L. chamaepitys . The Grão Mogol population has 4–5-locular ovaries and the Diamantina population has 2-locular ovaries but they are otherwise identical in all other characters of diagnostic importance. In view of the widespread locule number variation across the genus we see no reason to formally recognize these differences in L. chamaepitys .

Among the species of Lavoisiera with 2- and/or 4-locular ovaries and 5- or 6-merous flowers, L. chamaepitys superficially resembles L. humilis and L. minima . Lavoisiera humilis has solitary flowers and 1-nerved leaves that are glabrous throughout as in L. chamaepitys but its habit is often decumbent with juvenile leaves that differ in shape and width from the mature upper cauline leaves, its ovary is consistently 4-locular, and its mature leaf blades are linear-oblong with a sparsely serrulate-ciliate midvein abaxially. In L. minima the ovary is consistently 2- locular, the leaf blades are shorter (3.5–4 mm) and ovate to oblong with a broad callose-thickened margin that is distinctly short-serrulate to serrulate-ciliate.

Additional specimens examined:— MINAS GERAIS: Mpio. Diamantina , 4 km W of Hwy MG 220, along the road to Conselheiro Mata , 18°16'S, 43°42'W, Almeda et al. 8500 (CAS!, MO!, NY!, UEC!); Mpio. Diamantina , 13 km S of the main plaza in Diamantina on the road to São Gonçalo do Rio das Pedras, 18˚18.884’S, 43˚33.072’W, Almeda et al. 9099 (BHCB!, CAS!, RB!, UEC!); Mpio. Diamantina , 4 km W of Hwy MG 220 along S side of road to Conselherio Mata , -18.27630, -43.71281, Almeda et al. 9606 (CAS!, UEC!); Estrada para Conselheiro Mata ; Km 180, Furlan & Pirani CFCR 145 (SPF!, UEC!, US!); Mpio. Diamantina, Serra de São Francisco de Tejuco, Gardner 4586 (BM!, G!, K!, NY!, P!, R!, US!, W!); Mpio. Diamantina , ao Tombador,

LAVOISIERA ( MELASTOMATACEAE )

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MARTINS & ALMEDA

Glaziou 19195 (BM!, BR-2!, C!, F-3!, K!, LE!, MO!, NY-3!, R!, US!); Mpio. Diamantina, Serra do Espinhaço, Hatschbach 27486 (C!, COL!, MBM!, MO!, NY!, S!, US!); Mpio. Grão Mogol, Vargem do Quartel, ca. 7 km WSW Grão Mogol, Kral et al. 72691 (CAS!); Serra Grão Mogol, Maguire et al. 49216 (COL!, MICH!, NY!, UB!, US!); Pagão-Serra de Grão Mogol, Markgraf et al. 3437 (BHCB ex BHMH!, F!, RB!); Mpio. Diamantina , estrada Diamantina-Biribiri, 3 km do estádio, J. K. Mello-Silva et al. CFCR 5576 (SPF!, US!); Mpio. Grão Mogol, Serra de Grão Mogol, Mendes Magalhães 18110 (UB!); Mpio. Diamantina , estrada para Conselheiro da Mata, Km 187, 18°17'S, 43°37'W, Romero et al. 5417 (CAS-2!, HUFU); Mpio. Diamantina , lado esquerdo da Rodovia Diamantina-Curvelo, ca. 4.5 km de Diamantina, Sakuragui & V. C. Souza 163 (UEC!); Mpio. Diamantina , ad Biribiri prope Diamantina, Schwacke 7841 (BHCB!, R!, RB!); Mpio. Grão Mogol, Jambeiro, a 7 km de Grão Mogol, Zappi et al. CFCR 8527 (CAS!, SPF!, US!).

Figures

FIGURE 1. Images of Lavoisiera species. A. L. adamantium (Almeda et al. 8504). B–C. L. alba (Almeda et al. 9624). D–E. L. arachnoidea (unvouchered image). F. L. belinelloi (Almeda et al. 8532). G. L. bradeana (Almeda et al. 9718). H. L. canastrensis (Almeda et al. 7878). I. L. caryophyllea (Almeda et al. 9172). J–K. L. chamaepitys (Almeda et al. 8500). L. L. confertiflora (Almeda et al. 9725). Image credits: A–C, F–L. Frank Almeda; D–E. Karina Fidanza.

FIGURE 6. SEM images of seeds for representative Lavoisiera species showing lateral symmetrical plane (left) and detail of testa cells and cell wall microrelief (right). A−B. L. alba (Hatschbach 27282). C−D. L. caryophyllea (Tamashiro 25639). E−F. L. chamaepitys (Markgraf et al. 3437). Scale bars: A=150 µm, B=38 µm; C=380 µm, D=38 µm; E=231 µm, F=10 µm.

FIGURE 28. Distributions of Lavoisiera caryophyllea, L. chamaepitys, L. minima, L. senae, and L. vestita.

FIGURE 29. Lavoisiera chamaepitys. A. Habit. B. Detached branchlet. C. Adaxial leaf surface. D. Abaxial bract surface. E. Flower. F. Hypanthium and calyx lobes. G. Ovary cross-section. H. Petal with enlarged detail of margin (lower right). I. Ventral view of antesepalous stamen. J. Ventral view of antepetalous stamen. K. Post-mature fruit. L. Persisting columella and placenta. M. Seed. (Based on: A–M, Almeda et al. 8500, CAS, UEC.)