Comolia paraensis D.Nunes & P.J.F.Guim.

Silva, Diego Nunes Da, Rocha, Maria José Reis Da, Guimarães, Elsie Franklin & Guimarães, Paulo José Fernandes, 2024, Comolia paraensis (Melastomataceae), a striking new species of Marcetieae endemic to Pará, Brazil, Phytotaxa 646 (2), pp. 181-192 : 182-187

Comolia paraensis D.Nunes & P.J.F.Guim. , sp. nov. ( Figs. 1–2 )

Type: — BRAZIL. Pará: Oriximiná, rio Trombetas , ilha em frente ao Acampamento da Gutierrez , 02 July 1980 (fl., fr.), C.A. Cid, J. Ramos & C.D. Mota 1237 (holotype: RB!; isotypes: CAS, INPA!, MO!, NY!) .

Diagnosis: — Comolia paraensis can be distinguished from C. kuhlmannii by petiole with sparsely hirsute indumentum of glandular or eglandular trichomes, 0.5–1 mm long, or glabrous (vs. petiole with sparsely hirsute indumentum of eglandular trichomes 1.5–2.5 mm long, never glabrous in C. kuhlmannii ), chartaceous leaf blades (vs. membranaceous), trichomes (when present) 0.5–1 mm long on the abaxial surface (vs. 0.9–2 mm long, when present), bracts 7–9 × ca. 3 mm (vs. ca. 5 × 1 mm), trichomes 1–1.5 mm long (when present) at the margins (vs. 0.3–1 mm long, always present), and stalk 0.3–0.5 mm long, flat (vs. petiole ca. 1 mm long, canaliculate), bracteoles 5–5.5 mm long (vs. 4–4.7 mm long), oblong hypanthium (vs. campanulate) with tricomes 1–1.3 mm long on the striae or apex (vs. 0.5–1 mm long), sepals ca. 3 × 0.7–1 mm, oblong (vs. sepals 3–4 × 1–1.2 mm, narrowly triangular), petals 10–11 mm long (vs. ca. 13 mm long), and style 7–10 long (vs. ca. 11 mm long).

Subshrubs 0.2–1 m tall, erect or decumbent, terrestrial or rupicolous. Distal branches quadrangular, reddish or brownish when young, proximal branches succulent or not, gray; internodes (5–)18–23(–27) mm long, internodes and nodes with sparsely hirsute indumentum, glandular or eglandular trichomes, 0.2–1(–1.5) mm long. Leaves decussate, petiole 1–3 mm long, canaliculate or flat, sparsely hirsute indumentum, glandular or eglandular trichomes, 0.5–1 mm long, or glabrous; leaf blades (10–)17–25(–40) × 6–10(–14) mm, obovate or elliptic, flat, chartaceous; venation acrodromous, basal, 3-nerved with central and first pair prominent + 2 inconspicuous veins that do not reach the apex, rarely 3-nerved; base attenuate, margin serrate or crenulate, with the apex of each lobe with a eglandular trichome, 0.2–1 mm long, rarely glabrous, apex obtuse; abaxial surface light green, smooth, sparsely hirsute indumentum only on the veins, eglandular trichomes, 0.5–1 mm long, or glabrous; adaxial surface dark green, foveolate, sparsely hirsute indumentum, eglandular trichomes, 0.5–1 mm long, or glabrous. Flowers 4-merous, solitary or arranged in dyad, axillary and terminal, pedicellate; bracts 7–9 × ca. 3 mm, obovate, flat, persistent, 3-nerved, eglandular trichomes on the margin, 1–1.5 mm long, or glabrous, stalk 0.3–0.5 mm long, flat; bracteoles 5–5.5 × 1–1.5 mm, obovate, flat, persistent, 3-nerved, eglandular trichomes on the margin, ca. 1 mm long, or glabrous, stalk 0.3–0.5 mm long, flat; pedicel 1–3 mm long, terete, glabrous; hypanthium 3–5 × 2–3 mm, oblong, outer surface light green mixed to red, 8- striate, glabrous or with sparse eglandular trichomes on the striae or on the apex, 1–1.3 mm long, inner surface light green mixed to red, glabrous; sepals ca. 3 × 0.7–1 mm, oblong, light green mixed to red, concolorous, persistent, eglandular trichomes on the margin and apex, 0.5–1.5 mm long, inner surface glabrous, apex acute; petals 10–11 × 5–6 mm, obovate, pinkish or lilac, glabrous; stamens 8, subisomorphic, filaments filiform, erect, glabrous, white, ventral appendages oblong, bilobate, purple, dorsal appendages absent, pedoconnectives curved, purple, anthers oblong-linear, slightly curved or straight, smooth, purple, not rostrate, apex obtuse, blue; antesepalous stamens (larger) 4, filaments ca. 6 mm long, ventral appendages ca. 1 × 0.2 mm, pedoconnectives ca. 0.7 mm long, anthers ca. 6 mm long; antepetalous stamens (smaller) 4, filaments ca. 5 mm long, ventral appendages ca. 0.5 × 0.2 mm, pedoconnectives ca. 0.4 mm long, anthers ca. 5 mm long; ovary 1.5–3 × 1.5–2 mm, ovoid, light green, glabrous, pluriovulate, 2-locular; style 7–10 mm long, filiform, pinkish or lilac, glabrous, straight, apex pink; stigma punctiform, white. Fruits a loculicidal capsule 3–4 × 3–4 mm, ovoid, brownish, glabrous; seeds 32–62, 0.7–0.8 × 0.6–0.7 mm, cochleate, brownish in sicco, testa tuberculate; hilum basal and flattened.

Paratypes: — BRAZIL. Pará : Monte Alegre, 26 March 1924 (fl., fr.), J.G. Kuhlmann 1760 (RB! two sheets, UEC!, US!) ; ibid., campo ao largo do Km. 10 da estrada para C.A. N.P., 09 May 1953 (fl., fr.), D. A. Lima 53-1453 (IAN!, IPA!) ; ibid., Serra Itauajury , 06 March 1923 (fl.), A. Ducke s.n. (RB! barcode RB00562996) ; ibid., Serra do Itauajuri , ramal do PA 423 a norte de Monte Alegre, 01°51’37”S, 54°04’56”W, 354 m elev., 21 September 2017 (fr.), D.C. Zappi & M.T.C. Watanabe 3741 ( MG!) ; ibid., Serra do Itauajuri , lagoa da Panela , 01°51’38”S, 54°04’58”W, 370 m elev., 22 June 2018 (fr.), D.C. Zappi et al. 4301 ( MG!). Óbidos, Flota de Trombetas Sul, 06°08’S, 55°30’02”W [corrected coordinate: 1°08’00”S, 55°30’02”W], April 2008 (fl.), L.C.B. Lobato & C.A.S. da Silva 3489 ( MG!) ; região do Ariramba , campo do Jamaracarú, mata de igapó, 28 May 1957 (fr.), G.A. Black et al. 57-19731 (IAN!, NY!) ; ibid., campo do Mutum , 28 May 1957 (fl.), G.A. Black et al. 57-19705 ( IAN!) ; Ariramba , rio Jamaracarú , 28 May 1957 (fl.), P. Cavalcante 141 ( MG!). Oriximiná , Basin of Rio Trombetas , Rio Trombetas, across from Cachoeira Porteira, 01 June 1974 (fl., fr.), D.G. Campbell et al. P22428 (INPA!, K!, MO!, NY!, U!) ; ibid., 1km. above Cachoeira Porteira , 02 June 1974 (fl., fr.), D.G. Campbell et al. P22468 (INPA!, K!, NY!, US!) ; ibid., near Cachoeira Porteira , 28 May 1974 (fl.), D.G. Campbell et al. P22382 ( INPA!) ; ibid., Rio Trombetas , Cachoeira Porteira, 18 June 1980 (fl., fr.), C. Davidson & G. Martinelli 10347 (INPA!, MO!, NY!) ; ibid., Rio Trombetas , Cachoeira Porteira, próximo a foz do Rio Mapuera, 70 m elev., 18 June 1980 (fr.), G. Martinelli & C. Davidson 7037 (INPA!, MO!, NY!, RB!) ; ibid., rio Paru do Oeste , entre Cachoeira Pancada e rio Trombetas, 08 September 1980 (fl.), C.A. Cid et al. 2305 (INPA!, MG!, and MO! [all mixed with Rostranthera tetraptera ], NY!, RB!, US!) .

Etymology: —The specific epithet paraensis is a tribute to the state of Pará, Brazil.

Phenology: —Collected flowering and fruiting from March to July and also in September.

Distribution, Habitat, and Preliminary Conservation Status: — Comolia paraensis is endemic to the state of Pará, Brazil ( Fig. 3A ), occurring between 70–370 m elevation. Populations have been found in the municipality of Monte Alegre, located on the banks of the Amazon River, in seasonal streams within a matrix of stony savanna, at Serra do Itauajuri ( Fig. 3B ); in the municipality of Óbidos, in shrub formations on rocky outcrops, in region known as “Ariramba”; while in the municipality of Oriximiná, populations have been found mainly in campinas with moist and sandy soil in the surroundings of the Cachoeira Porteira community ( Fig. 3C ), close to the Trombetas River (a tributary of the Amazon River) and also in the campinas close to the Paru do Oeste River (a tributary of the Trombetas River). The Amazonian campinas and savannas have been the target of human interventions such as agriculture, cattle ranching, fires, and mining ( Fine & Bruna 2016; Carvalho & Mustin 2017). Comolia paraensis occupies precisely these habitats in areas that are not protected by Brazilian environmental laws, except for the populations in the Cachoeira Porteira community and Ariramba region that are in the Trombetas River Biological Reserve and Trombetas State Forest, respectively, but even in these regions mining and deforestation continues ( Bentes et al. 2021; Gonella et al. 2020). Furthermore, the possibility of installing the Cachoeira Porteira Hydroelectric Plant could completely change the landscape ( Brasil 2007; Bentes et al. 2021; Reale & Cavalcante 2021). Concomitant to the threats, C. paraensis has a restricted geographic distribution (EOO ≅ 9,621.3 km 2 and AOO = 24 km 2). Therefore, we suggest that its conservation status should be categorized as Endangered [EN B1a,b(iii) + 2a,b(iii)].

Notes: —The specimens of Comolia paraensis from Serra do Itauajuri, Monte Alegre, have historically (see Paratypes from Monte Alegre) been collected with an irregularly lump-shaped basal stem swelling (caudex) which is an indication of succulence in the basal branches ( Eggli & Nyffeler 2023; see also Figs. 2C–D ). Eggli & Nyffeler (2009: 33) defines succulence as “ a combination of morphological/anatomical considerations (storage in living tissues of one or several plant parts), ecological conditions (occurrence in temporarily arid environments), and physiological aspects (spending utilizable water in physiological processes such as photosynthesis or growth / flowering during the dry season) ”. In C. paraensis , the caudex on the basal branches must be a functional strategy linked to droughts in Serra do Itauajuri, where the species occurs close to seasonal streams of savanna, which disappear during the dry season. In contrast, the caudex has not been found in specimens collected from sandy and moist soil, from the campinas in the surroundings of the Cachoeira Porteira community and Paru do Oeste River. Although caudex has not been observed in populations of C. paraensis in the campinas, in these environments many species present traits linked to low nutrient availability, drought, and defense ( Fine & Baraloto 2016). The intriguing case of C. paraensis must be studied comparatively between populations, as the caudex is possibly a strategy to face the adversities in the savanna.

In Melastomataceae, Eggli & Almeda (2023) reported true succulence in branches of Merianthera Kuhlmann (1935: 231) and Sonerila Roxburgh (1820: 180) , genera from tribes not phylogenetically related to Marcetieae ( Penneys et al. 2022) . Within Marcetieae , succulence has only been reported in the leaves of Fritzschia cordifolia R.Romero, D.Nunes & M.J.R.Rocha (in Romero et al. 2019: 664) ( Rocha & Silva 2023) and now at the base of the branches of C. paraensis . Still in Marcetieae , the herbaceous and predominantly annual genera Noterophila Martius (1831: 110) and Siphanthera Pohl ex Candolle (1828: 121) have branches that are merely swollen at the base ( Rocha et al. 2022), rather than truly succulent (see Eggli & Nyffeler 2009).

Affinities: —Some specimens of Comolia paraensis have been historically identified as C. veronicifolia , a heterotypic synonym within the C. villosa complex, which is now considered an accepted species. Comolia paraensis has also been mentioned as a non-nominated new species in the Monte Alegre species list ( Devecchi et al. 2020). However, C. paraensis is morphologically more similar to C. kuhlmannii and C. veronicifolia , which should be considered a distinct species from C. villosa . Comolia kuhlmannii is easily distinguished from C. villosa sensu stricto by the obovate leaf blades in C. kuhlmannii (versus elliptic in C. villosa ) and the margin with eglandular trichomes (vs. glandular). Otherwise, C. veronicifolia is distinguished from C. villosa by combining the abaxial surface of the leaf blade with trichomes only on the veins in C. veronicifolia (vs. with trichomes on and between the veins in C. villosa ), the adaxial surface of the leaf blade glabrous or with sparsely hirsute indumentum (vs. hirsute or hispid), and obovate bracts (vs. elliptical).

Comolia paraensis is morphologically close to C. kuhlmannii and C. veronicifolia due to the internodes with sparse trichomes, bracts and bracteoles with trichomes at the margins, obovate or elliptic leaf blades, abaxial surface of the leaf blades with trichomes only on the veins or glabrous, flowers organized in dyads or rare solitary, and the length of the parts of the stamens overlap. However, C. paraensis is differentiated from C. kuhlmannii due to the set of characters mentioned in the Diagnosis (see also Tab. 1 ). Furthermore, both species do not occur in sympatry ( Fig. 3 ).

Comolia paraensis is distinguished from C. veronicifolia due to the petiole most often glabrous (vs. with hirsute indumentum in C. veronicifolia ), solitary flowers or arranged in dyad, axillary and terminal (vs. dyad or dichasium, only axillary), and antesepalous stamens with appendages ventral ca. 1 × 0.2 mm, pedoconnectives ca. 0.7 mm long, and anthers ca. 6 mm long (vs. appendages ventral 0.5–1 × 0.2–0.4 mm, pedoconnectives 0.7–1.5 mm long, and anthers 4–6 mm long) (see Tab. 1 ). Concomitantly, both species do not occur in sympatry ( Fig. 3 ).

Figures

FIGURE 1. Illustration of Comolia paraensis. A. Fertile branch. B. Succulent branch at the base. C. Indumentum on the distal branches. D. Abaxial surface of the leaf. E. Adaxial surface of the leaf. F. Inflorescence. G. Flower. H. Sepal. I. Petal. J–M. Antesepalous stamens. J. Stamen. K. Ventral view. L. Dorsal view. M. Lateral view. N–Q. Antepetalous stamens. N. Stamen. O. Ventral view. P. Dorsal view. Q. Lateral view. R. Gynoecium. S. Capsule within the hypanthium. Black scale = 1 mm; gray scale = 1 cm. Vouchers:A and C–S draw from C.A. Cid et al. 1237 (RB); B draw from D.C. Zappi et al. 4301 (MG).

FIGURE 2. Comolia paraensis in the field. A–B. Fertile branches. B’. Flower detail. C–D. Succulent proximal branches. E. Flower after opening. F–G. Flower in anthesis with preyed stamens. H. Capsules within the persistent hypanthium. Photos and vouchers: Daniela C. Zappi (A, C, H; from D.C. Zappi et al. 4301), Rafael G. Barbosa-Silva (B, D, F–G; still unvouchered), and Pedro L. Viana (E; unvouchered and in cultivation).

FIGURE 3. Geographic distribution map of Comolia paraensis and putative relatives. A. Distribution of Comolia kuhlmannii (orange circles), C. paraensis (red circles), and C. veronicifolia (black circles). B. Habitat of the C. paraensis in Monte Alegre, Pará, Brazil. C. Campina in Cachoeira Porteira, Pará, Brazil. Photos: Daniela C. Zappi (B) and João Batista F. da Silva (C).