Psyllocarpus vianae Sobrado, J.A.M.Carmo & R.M.Salas, 2022

Sobrado, Sandra V., do Carmo, João A. M., Simões, André O. & Salas, Roberto M., 2022, Two new species of Psyllocarpus (Spermacoceae, Rubiaceae) from the state of Minas Gerais, southeastern Brazil, European Journal of Taxonomy 806, pp. 161-176 : 166-172

Psyllocarpus vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.

urn:lsid:ipni.org:names:77296004-1

Figs 2 , 3J–R , 4I–P , 5E–H , 6G–M , 7

Diagnosis

Psyllocarpus vianae sp. nov. is similar to P. laricoides , but differs by the flowering branches determinate (vs indeterminate in P. laricoides ), inflorescences in terminal glomerules (vs axillary inflorescences in 1-flowered cymes), corolla urceolate (vs infundibuliform), completely purple or the lower half of the tube white (vs tube purple and lobes light blue), tube 1.22–1.6 mm long (vs 2.9–6.7 mm long), the upper third of the lobes reflexed in mature flowers and the rest forming a false tube (vs plane to slightly reflexed in mature flowers, not forming a false tube), filaments 0.41–0.73 mm long (vs 0.2–0.4 mm long), style 0.14–0.24 mm long (vs 0.3–0.7 mm long), and seeds broadly obovate in outline (vs elliptic to broadly elliptic in outline).

Etymology

The specific epithet honours the Brazilian botanist Pedro Lage Viana, who works on the systematics of the Poaceae Barnhart with emphasis on the Bambusoideae Luerss., as well as floristic inventories in many Brazilian phytogeographic domains, but currently concentrated in the Brazilian Amazon. ʻPedrinhoʼ collected the first specimens of both species described in this paper, as he is also known to have greatly contributed to the knowledge of the flora of the Espinhaço range, especially in Minas Gerais.

Material examined

Type

BRAZIL • Minas Gerais, Joaquim Felício, Serra do Cabral , campos rupestres, “con áreas de suelos arenosos blanquecinos” [with areas of white sandy soils]; 17°41′57″ S, 44°16′29″ W; 1140 m a.s.l.; 17 Apr. 2012; Viana, Salas, Sobrado & Mota 5887; holotype: BHCB[158411] !; isotype: CTES !.

Paratype BRAZIL • Minas Gerais, Joaquim Felício, Serra do Cabral , “estrada passando pelo Parque Estadual da Serra do Cabral (acesso Joaquim Felício), próximo ao talhão de Eucalipto” [road passing through the Serra do Cabral State Park (entrance Joaquim Felício), near the Eucalyptus stand]; 17°41′57″ S, 44°16′28″ W; 15 Jan. 2015; Carmo & Scatigna 294; UEC[208461] !.

Description

Subshrubs, 0.5–1.2 m tall, sympodial. Stems sparsely branched distally, erect, internodes 1.78–7.24 mm long, 2.02–4.62 mm wide at the apex, 0.46–1.24 mm wide at the middle, tetragonal to subtetragonal and scabridous, bark peeling from older internodes, foliar scars conspicuous. Stipular sheaths 0.48–1.12 mm long, scabridous to glabrous, (4)5–6-fimbriate on each side of the stem, fimbriae 0.2–0.76 mm long, narrowly triangular, scabridulous. Leaves opposite, with axillary brachyblasts forming fascicles, leaf blades 2.22–6.95 × 0.23–0.6 mm, erect to slightly reflexed, decussate, sessile, linear to terete, apex obtuse to acuminate, glabrous, margin scabridulous. Flowering branches determinate, 1.12–6.69 cm long, unbranched or with 3–5 branches per flowering axis, inflorescences in terminal glomerules, 4–12-flowered, 5.37–11.29 mm wide, peduncle 2.97–6.06 mm long, external bracts 2, 2.28–3.22 × 0.24–0.6 mm, linear to terete, apex obtuse, glabrous. Flowers sessile, homostylous; hypanthium 1.14–2.06 × 0.76–1.31 mm, obconic, glabrous; calyx tube 0.15–0.45 mm long, 2-lobate, 6–10 fimbriae along the calyx rim between the lobes, 0.12–0.63(1.14) mm long, colleter tipped, calyx lobes 1.32–2.18 × 0.19–0.49 mm, narrowly elliptic to linear, glabrous, margin slightly scabridulous; corolla 2.63–3.55 mm long, urceolate, completely purple or the lower half of the tube white, corolla tube 1.22–1.6 mm long, 1.07–1.6 mm diam., external surface papillate, internal surface glabrous from the base up to the base of the filaments, and sparsely monoliform trichomes between the anthers, (3)4-lobate, corolla lobes 1.29–2.25 × 0.79–1.29 mm, the upper third reflexed (from posanthetic to mature flowers), the rest aligned with the adjacent lobes forming a false tube, triangular to broadly ovoid, external surface papillate, internal surface papillate on the upper half, with moniliform trichomes densely concentrated on the base, deeply deltoid in preanthetic bud, this ca 1.26 mm diam., apex mucronate; stamens included, inserted near the sinuses of the corolla lobes, filaments 0.41–0.73 mm long, anthers 0.75–1.09 mm long, occasionally with expansion of the connective tissue (0.08–0.1 mm long), orbicules present covering uniformly the inner wall of dehiscent anthers, pollen 5-zonocolpate, circular outline in polar view, small-sized (P = 16–19 µm), prolate-spheroidal to subprolate (P/E = 1.13–1.29), long and narrow ectocolpi (11–16 µm long), endocingulum 3–5 µm wide, tectum psilate microspinose, tipped microspines 0.25–0.3 mm long, distributed around the ectocolpi, exine 0.66–0.71(1) µm thick; style included, 0.14–0.24 mm long, stigma 0.19–0.3 mm long, bilobate, lobes inconspicuous; nectariferous disk entire, 0.83–1.15 mm diam., with striate cells. Capsule 3.27–4.69 × 1.98–2.52 mm, pedicel 0.43–0.62 mm long, oblongate to obovate in outline, strongly compressed parallel to the septum, glabrous, calyx lobes persistent, dehiscent from the apex downwards, valves persistent from which the seeds are shed after dehiscence, septum persistent, 2.71–4.26 × 1.43–2.23 mm. Seeds 2, 1.86–3.2 × 1.69–2.02 mm, obovate in outline, strongly compressed, ventral surface covered by diffuse strophiole, 0.98 × 0.35–0.61 mm, dorsal surface slightly convex, testa subtuberculate, with digital-like cells pressed (101.22–146.86 × 19.98–32.95 µm), radially arranged.

Distribution, habitat, and phenology

Psyllocarpus vianae sp. nov. grows on sandy and rocky soil in the “campo rupestre” vegetation, being recorded from 1100 to 1200 m a.s.l. It is endemic to the Serra do Cabral, in the municipality of Joaquim Felício, Minas Gerais ( Fig. 7 ). Specimens were collected with flowers and fruits on January and April.

Preliminary conservation status

Psyllocarpus vianae sp. nov. does not occur within the limits of any protected area in Minas Gerais. However, it may occur within the limits of the Parque Estadual da Serra do Cabral, a conservation unity of integral protection nearby, pending further botanical investigation in the region to evidence this record. Psyllocarpus vianae sp. nov. presents AOO equal to 4 km 2. Therefore, we believe that this species would be considered critically endangered (CR B2abiii) in an official IUCN red list assessment, based on its AOO less than 500 km 2 (kml file available as Supp. file 2), occurrence in one location, and continuing decline inferred on quality of habitat due to the impacts on the “campo rupestre” vegetation, which in this case is also associated with the expansion of eucalyptus plantations in the region, as noticed by us during fieldwork.

Figures

Fig. 2. Psyllocarpus vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 5887 (CTES). A. Habit. B. Inflorescences at the apex of flowering branches. C. Detail of an inflorescence. D. Stipular sheath. E. Preanthetic flower bud. F. Flower. G. Hypanthium, calyx, style, and stigma. H. Opened corolla. I–M. Fruit. I. Dehiscent capsule, lateral view. J. Septum. K. Valve, seed, and septum, cross section. L. Valve, dorsal view. M. Valve, ventral view. N–O. Seed. N. Dorsal view. O. Ventral view. Illustration: L. Simón.

Fig. 3. Flower micromorphology. A–I. Psyllocarpus itakangapyra Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 4415 (CTES). A. Flower bud. B. Papillate external surface of the corolla. C. Hypanthium, calyx, style, and stigma. D. Detail of style and stigma. E. Opened corolla. F. Papillate internal surface of the corolla lobes. G. Moniliform trichomes at internal surface of the corolla. H. Nectariferous disk, top view. I. Detail of striate nectariferous disk cells and functional stomata. J–R. P. vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 5887 (CTES). J. Flower bud. K. Papillate external surface of the corolla. L. Hypanthium, calyx, style, and stigma. M. Detail of style and stigma. N. Opened corolla. O. Papillate internal surface of the corolla lobes and moniliform trichomes. P. Inner wall of a dehiscent anther, showing the prescence of orbicules. Q. Nectariferous disk, top view. R. Detail of striate nectariferous disk cells. Scale bars: A, C, E, J, L, N 200 µm; B, G, K, R = 20 µm; D, F, M = 50 µm; H, O, Q = 100 µm; I = 10 µm; P = 2 µm.

Fig. 4. Fruit and seed micromorphology. A–H. Psyllocarpus itakangapyra Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 4415 (CTES). A–E. Capsule. A. Dehiscent capsule, lateral view. B. Valve, dorsal view. C. Valve, ventral view. D. Cross section capsule. E. Septum. F–H. Seed. F. Dorsal view. G. Ventral view, with diffuse strophiole. H. Detail of the testa. I–P. P. vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 5887 (CTES). I–M. Capsule. I. Dehiscent capsule, lateral view.J. Valve, dorsal view. K. Valve, ventral view. L. Cross section of the valve, seed, and septum. M. Septum. N–P. Seed. N. Dorsal view. O. Ventral view. P. Detail of the testa. Abbreviations: s = seed; se = septum; v = valve. Scale bars: A–G, I–O = 200 µm; H, P = 20 µm.

Fig. 5. Pollen morphology (SEM). A–D. Psyllocarpus itakangapyra Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 4415 (CTES). A. Polar view. B. Equatorial view. C. Detail of apocolpium. D. Detail of the colpus and spinules. E–H. P. vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov.; P.L. Viana et al. 5887 (CTES). E. Polar view. F. Equatorial view. G. Detail of the inner side of a pollen fragment showing the endocingulum (en). H. Detail of the colpus and spinules. Scale bars: A–B, E–G = 2 µm; C–D, H = 1 µm.

Fig. 6. A–F. Psyllocarpus itakangapyra Sobrado, J.A.M.Carmo & R.M.Salas sp. nov. A. Habitat, “campo rupestre” in Itacambira, Minas Gerais. B. Habit. C. Branch portion, showing the leaves. D. Inflorescences at the apex of flowering branches. E. Detail of the flowers. F. Capsules. G–M. P. vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov. G. Habitat, “campo rupestre” in Serra do Cabral, Minas Gerais. H. Habit. I. Branch portion, showing the leaves. J. Inflorescences at the apex of flowering branches. K. Detail of preanthetic flower buds. L. Detail of an opened flower. M. Dehiscent capsule. Photos: A, C, G–J = R.M. Salas; B, D–F = J.A.M. Carmo; K–L = P.L. Viana; M = S.V. Sobrado.

Fig. 7. Distribution map of Psyllocarpus itakangapyra Sobrado, J.A.M.Carmo & R.M.Salas sp. nov. and P. vianae Sobrado, J.A.M.Carmo & R.M.Salas sp. nov. in the state of Minas Gerais, Brazil.