Commelina scabrata Seub.

Commelina scabrata Seub. View in CoL

Figs 4 View Fig , 17–18 View Fig View Fig ; Table 2 View Table 2

Commelina scabrata Seub. View in CoL (Seubert in Martius 1855: 266). – Phaeosphaerion persicariifolium var. scabratum (Seub.) C.B.Clarke ( Clarke 1881: 137) View in CoL .

Etymology

From the Latin ʻ scabrā ʼ (meaning ʻrough, scratchy, itchyʼ) + the suffix ʻ -āta ʼ (indicating the possession of a particular feature), in reference to its leaves covered by scabrid hairs.

Type material

BRAZIL – Espírito Santo • crescit in interioribus prov. Bahiensis ; s.dat.; fl.; C.F.P. von Martius s.n.; lectotype: M [ M0274913 ]!, designated by Hassemer et al. (2016); isolectotype: M [ M0274914 ] !.

Selected material examined

BRAZIL – Espírito Santo • Estação Biológica de Santa Lúcia , trilha para o túmulo de Augusto Ruschi, ao lado da ponte José Molina ; 26 Jun. 2012; fl., fr.; M.O.O. Pellegrini et al. 248; RB, VIES . – Rio de Janeiro • Santa Maria Madalena Parque Estadual do Desengano. Horto Santos Lima , cede do parque , próximo a caixa d’água , no bambusal ; 6 Feb. 2016; fl., fr.; M.O.O. Pellegrini et al. 486; K, P, RB, SPF, US. – São Paulo • Itanhaém, Ilha Queimada Grande ; 5 Mar. 2015; fl.; A.M. Magalhães & L.G.S. Amorim 95; RB, SPF .

Description

Herbs 20–50 cm tall, ascending, perennial, robust, rupicolous or terrestrial. Roots fibrous, thin. Rhizome short. Stems monomorphic, ascending, unbranched or branched only at base; internodes 0.6–8.4 cm long, distally shorter, green to dark green, scabrid with prickle-hairs to hispid with a mixture of prickle- and acicular hairs, hairs hyaline, longer acicular ones sometimes rusty, with a line of acicular hairs opposite to the leaves, hairs dark brown to red to dark red. Leaves distichously-alternate, congested in the upper part of the stem, pseudopetiolate; sheaths 0.9–2.8 cm long, light green, sometimes suffused with magenta to red opposite to the blade, scabrid with prickle-hairs to hispid with a mixture of prickle- and acicular hairs, hairs hyaline, with a line of hispid hairs opposite to the leaves, hairs acicular, dark red to dark red to atro-vinaceous, margin upright, hispid, hairs acicular, dark red to dark red to atro-vinaceous; pseudopetiole 0.4–3.9 cm long; blades (2.2–)4.3–13.7 × 0.9–3.6 cm, narrowly oblong to narrowly elliptic, obliquely asymmetric, thinly chartaceous to chartaceous, adaxially green to dark green, abaxially light green, sometimes with vinaceous to dark purple variegation, adaxially glabrous to hispid, abaxially hispid, hirsute along the midvein, hairs acicular, rusty or hyaline, base asymmetric, cuneate, margin flat, scabrid, apex acuminate to long-acuminate; midvein conspicuous, adaxially impressed, abaxially prominently obtuse, secondary veins 3–4 pairs, adaxially conspicuous, abaxially inconspicuous, becoming conspicuous on both sides when dry. Synflorescence composed of a solitary main florescence or main florescence plus 1–2 co-florescences, restricted to the apex of the stems. Inflorescences terminal or apparently so, peduncle 4.3–9.1 mm long, shorter than ½ length of the spathe, straight, glabrous to sparsely scabrid with prickle-hairs, hairs hyaline; spathe 1.3–3.6 × 1.9–4.3 cm, widely depressed ovate-triangular to depressed ovate-triangular, patent to the peduncle, concolourous with the leaves, internally conspicuously mucilaginous, base connate up to the apex or almost so, truncate, externally hispid to hirsute, hairs hyaline or rusty, margin flat, apex obtuse to acute, straight, veins 3–4 pairs, inconspicuous, becoming conspicuous when dry; upper cincinnus vestigial, flowerless, peduncle 1.9–3.3 cm long, included, gently recurved at pre-anthesis, anthesis, post-anthesis and fruit, sparsely puberulous with minute hook-hairs, hairs hyaline; lower cincinnus 1–3-flowered, flowers mainly bisexual, rarely staminate, peduncle 3.3–5.4 cm long, thickened in fruit, glabrous to sparsely puberulous with minute hook-hairs towards the apex. Flowers chasmogamous, strongly zygomorphic, enantiostylous (style gently dislocated to the opposite side to the medial stamen); floral buds 2.2–6.5 × 3.7–6.1 mm, obovoid, light green or light blue, glabrous; pedicel 0.9–1.4 mm long, deflexed in bud and at anthesis, reflexed and elongating in fruit, light green, glabrous; sepals hyaline, persistent and accrescent in fruit, dorsal sepal 3.2–4.8 × 1.9–2.6 mm, elliptic to narrowly triangular, concave, glabrous, apex acute, lower sepals 4.2–6.3 × 4.7–5.9 mm, shortly-clawed, connate up to the upper third, oblique-obovate to widely oblique-obovate, concave, glabrous, apex round; paired petals 9.8–15.3 × 8.8–13.8 mm, clawed, claw 3.9–6.1 mm long, white to light blue, limb 5.9–9.2 × 8.8–13.8 mm, widely transversally rhombic to widely depressed obovate, sky blue, base asymmetric, cuneate, apex obtuse to round, medial petal 4.3–6.1 × 1.4–3.2 mm, sessile, lanceolate to ovate, entire, apex involute, discolourous with the paired petals, white, hyaline, glabrous on both sides, apex acute to acuminate; staminodes 3, medial staminode equal to the laterals, filaments 3.4–5.1 mm long, straight to arcuate-recurved, white, apex yellowish-orange to cream-orange, antherodes 1.6–1.8 × 1.4–1.6 mm, X-shaped, yellow, minute pollen sacs between the upper and lower lobes present, non-polliniferous or producing very few grains, not apiculate between the upper lobes, upper lobes conspicuous, very widely obtriangular to subquadrangular, larger than the lower, lower lobes widely oblong to subquadrangular; lateral filaments 6.7–10.3 mm long, straight to very gently sigmoid, base gently recurved, white, base light green, apex yellowish-orange to cream-orange, anthers 1.6–1.9 × 1.3–1.5 mm, held with the medial anther, elliptic to ovate, orange-yellow to orange, pollen yellowish-orange to cream-orange, drying orange-yellow to apricot; medial filament 5.2–9.4 mm long, straight to arcuate-decurved, apex suddenly recurved, white, apex yellowish-orange to cream-orange, anther 1.9–2.2 × 1.4–1.7 mm, held with the lateral anthers, widely oblong to widely elliptic, slightly curved, orange-yellow to orange, connective oblong, orange, anther sacs not appressed to each other, pollen yellowish-orange to cream-orange, drying orange-yellow to apricot; ovary 1.2–1.7 × 0.9–1.5 mm, 3-carpellate, 5-ovulate, very widely fusiform to subglobose, green, sparsely verrucose, puberulous with glandular microhairs, style 1–1.3 cm long, equalling or exceeding the stamens, very gently sigmoid, apex recurved, base tapering into the ovary, apex strongly involute, white, base light green, apex yellowish-orange to cream-orange, deciduous in fruit, stigma trilobate, tan-coloured. Capsules 1–2 per spathe, 1.3–1.6 × 1–1.3 cm, prismatic, sessile, fruit wall thin, apex rostrate, slightly constricted between the seeds, tan-coloured to greenish-brown, speckled with dark brown, shiny when immature, becoming off-white with tan-coloured speckles when parasitised by weevil larvae or when mature, opaque, verrucose, 3-locular, unequally 2-valved, dorsal locule 1-seeded, indehiscent, ventral locules 1-seeded, dehiscent, valves splitting only up to mid-length. Seeds dimorphic, brown to dark brown; dorsal locule seed 0.9–1.4 × 0.4–0.7 cm, adnate to the fruit wall, ellipsoid, dorsiventrally compressed, ventrally flattened, slightly cleft towards the embryotega, testa shallowly foveolate, non-farinose, embryotega semidorsal, conspicuous, without a prominent apicule, hilum linear, ca the same length as the seed; ventral locule seeds 1–1.4 × 0.4–0.6 cm, free from the fruit wall, ellipsoid to slightly falcate, ventrally flattened, not cleft towards the embryotega, testa sparsely echinate, sparsely farinose, farinae white, embryotega semilateral, conspicuous, with a prominent apicule, hilum C-shaped, ca the same length as the seed.

Distribution

Commelina scabrata is endemic to Brazil, States of Espírito Santo, Rio de Janeiro and São Paulo ( Fig. 4 View Fig ).

Ecology

It grows in the understory of conserved and disturbed Atlantic Forest fragments, between 600–1000 m a.s.l. It is found growing along or near watercourses or in permanently moist forest patches.

Phenology

It was found in bloom and fruits from January to June. The floral morphology, more specifically, the prematurely involute style causing the stigma to be held with the anthers combined with the lack of observed floral visitors in the wild and cultivation, indicate this self-compatible species mainly relies on selfing (Pellegrini, pers. obs.).

Commelina scabrata has a unique association with a weevil (Curculionoidea, Coleoptera) ( Fig. 18 View Fig ). Each capsule is predated by a single egg laid inside the fruit during its initial developmental stages. The larva bores its way out of the fruit, eating the developing seeds and septae, leaving intact the outer part of the fruit ( Fig. 18C View Fig ). The remaining capsule wall is used by the larva as a shelter ( Fig. 18A–C View Fig ), where they grow to the size of the capsule ( Fig. 18G–H View Fig ). The fruit might also serve as a shell for the weevil’s pupa stage, but further observations are still required (Pellegrini, pers. obs.). After the weevil has left the predated fruit, the capsule acquires an off-white and opaque colouration, which is retained in herbarium specimens ( Fig. 18D View Fig ), in opposition to its immature colouration (tan-coloured to greenish-brown, speckled with dark brown, and shiny; Figs 17J View Fig , 18E–F). Out of the analysed herbarium specimens and plants studied in the field and kept in cultivation, between 80–90% of the capsules were predated, significantly affecting the species’ seed set. Unfortunately, we have been unable to observe and/or collect pupa and adult stages of this weevil, preventing a more precise identification.

Vernacular name

Trapoeraba lixa ( Brazil).

Conservation

Despite its wide EOO (222 614 km 2), C. scabrata has a considerably reduced AOO (ca 412 km 2) due to the small number of known records and extant populations. All observed populations were small, with fewer than 20 mature individuals, all of them growing in disturbed environments (Pellegrini, pers. obs.). Despite flowering and fruiting being common and fairly constant, over 90% of observed fruits were predated by weevil larvae ( Fig. 18 View Fig ). The predated fruits have all their seeds entirely eaten by the larvae, effectively preventing successful sexual reproduction. The frequency of predation is so high that all analysed herbarium specimens presented predated fruits and no seeds. Mature seeds were only accidentally but successfully observed in cultivation ( Fig. 17K–L View Fig ). Nonetheless, the observed populations seem to remain stable, primarily due to clonal reproduction (Pellegrini, pers. obs.). Thus, following the IUCN (2012) criteria and the IUCN Standards and Petitions Committee (2024) recommendations, we suggest C. scabrata be considered Endangered [EN, B2b(ii, iii)c(iv)+C2a(i)].

Remarks

Similar to Commelina bambusifolia , due to their hirsute leaf-sheaths, blades narrowly oblong to narrowly elliptic, obliquely asymmetric, abaxially hirsute along the midvein, margin smooth, apex acuminate to long-acuminate, upper cincinnus vestigial and included, lower cincinnus glabrous, paired petals limb with base cuneate, medial anther lacking a vinaceous to dark purple spot on the connective, fruits opaque off-white when mature, all locules 1-seeded ( Table 2 View Table 2 ). However, it can be differentiated by its leaf-blades hispid on both sides, hairs rusty or hyaline, base cuneate, paired petals limb sky blue, fruits prismatic, sparsely verrucose, apex aristate, consistently parasitised by weevil larvae, unequally 2-valved, valves splitting only up to mid-length, seeds dimorphic, dorsal locule seed adnate to the fruit wall, and ventral locule seeds free from the fruit wall ( Table 2 View Table 2 ). It is superficially similar to C. obliqua and C. rufipes due to its rusty leaves and white fruits. However, it can be readily differentiated by its aborted and included upper cincinnus (vs developed and exserted in C. obliqua and C. rufipes ), paired petals blue with a cuneate limb (vs white, cordate), involute medial petal (vs straight), antherodes with upper lobes larger than the lower ones (vs smaller), anthers orange-yellow to orange (vs yellow), fruits dehiscent, prismatic, opaque and verrucose (vs indehiscent, globose to subglobose, shiny and smooth), and seeds dimorphic and ornate (vs monomorphic and smooth to inconspicuously foveolate).

The capsules of C. scabrata are very peculiar and present a unique combination of characters in the genus (i.e., prismatic shape, fruit wall thin, apex rostrate, slightly constricted between the seeds, verrucose ornamentation, dark brown maculated colouration when immature, changing to off-white when parasitised by weevil larvae or when mature, indehiscent dorsal valve and ventral valves splitting only up to mid-length). The ventral seeds of C. scabrata are also unique amongst the Neotropical species of Commelina due to their D-shaped outline and sparsely echinate testa. The dorsal seeds also stand out due to having a different outline, colouration, testa ornamentation and deposition, embryotega position and development, and hilum shape. Finally, the aforementioned paired petals limb with cuneate limb base are, so far, known only for C. bambusifolia and C. scabrata amongst Neotropical Commelina . With such a combination of peculiar and unique morphological characters, it seems surprising that C. scabrata has remained an obscure and misunderstood species for so long.