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| Mitracarpus semirianus J.A.M.Carmo & Scatigna, in Carmo, Scatigna, Shimizu & Simões, 2022. |
Abstract
Background and aims – Mitracarpus semirianus, an overlooked new species from the “campo rupestre” of the Chapada Diamantina, in the state of Bahia, northeastern Brazil, is here described and illustrated. Specimens of the new species have been previously identified as M. frigidus or M. lhotzkyanus, with which its distinction is discussed. We also provide an updated description of the latter, with notes on its type specimens. In addition, we comment on the distribution, habitat, and preliminary conservation status of both M. semirianus and M. lhotzkyanus. We also provide an updated identification key to the species of Mitracarpus occurring in Brazil.
Material and methods – This study was based on fieldwork collections and observations and analysis of specimens deposited in herbaria. Preliminary conservation status assessments follow the IUCN Red List criteria.
Key results – Mitracarpus semirianus differs from M. frigidus and M. lhotzkyanus by its glabrous stems, winged at each angle, wing margin hirsute, glabrous leaf blades, and the oblongoid and slightly compressed seeds, with a smooth longitudinal groove dorsally and an inverted “Y”-shaped groove ventrally. The new species is assessed as Endangered according to the IUCN criteria. Furthermore, it is more likely that Riedel, not Lhotzky, collected the original material of the name M. lhotzkyanus. This species is glabrate, not completely glabrous, presenting a generally strigose indumentum on the stems, stipular sheaths, and leaf blades.
Keywords: Espinhaço Range, morphology, Rubioideae, Spermacoce clade, taxonomy
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| Mitracarpus semirianus J.A.M.Carmo & Scatigna. A. Branch portion with a terminal glomerule. B. Branch portion with terminal and axillary glomerules. C. Stem and stipule. D. Flower. E. Detail of the exteranal surface of the corolla. F. Dissected corolla, with stamens, style, and stigma. G. Capsule. H. Inferior portion of a dehiscent capsule. I. Seed, dorsal (left) and ventral (right) views. J. Detail of the testa of the seed. From J.A.M. Carmo & A.V. Scatigna 420. Drawn by Klei Sousa. |
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| Mitracarpus semirianus J.A.M.Carmo & Scatigna. A. Inflorescence. B. Individuals. C. Habitat. D. General view of the site of collection. Photographs by João Carmo (A–C) and André Scatigna (D). |
Mitracarpus semirianus J.A.M.Carmo & Scatigna, sp. nov.
Diagnosis – Mitracarpus semirianus is similar to M. frigidus, but differs by the glabrous stems (vs puberulent to glabrous in M. frigidus), winged at each angle (vs ribbed at each angle), wing margin hirsute (vs rib margin hirsute, strigose, or glabrous); elliptic, ovate, or narrowly ovate leaf blades, glabrous (vs narrowly ovate, rarely linear leaf blades, hirsute, pubescent, strigose, or glabrous); terminal glomerules, rarely one axillary (vs terminal and axillary, rarely just terminal); oblongoid, slightly compressed seeds (vs oblongoid to globose seeds), with a smooth longitudinal groove dorsally and an inverted “Y”-shaped groove ventrally (vs cruciform depression dorsally and an “X”-shaped groove ventrally). Mitracarpus semirianus is also similar to M. lhotzkyanus, but differs by the stems winged at each angle (vs ribbed at each angle), wing margin hirsute (vs rib margin strigose to glabrous), leaf blades with strigulose and revolute margin (vs glabrous to strigose margin and slightly revolute near the base), and the oblongoid, slightly compressed seeds (vs oblongoid to ellipsoid seeds), with an inverted “Y”-shaped groove on the ventral surface (vs a rectangular groove on the ventral surface).
Etymology – The specific epithet honours Professor João Semir, who worked at the University of Campinas (Unicamp) and passed away on the 8th of November 2018. Professor Semir dedicated his life to the study of plants. His invaluable contribution to science and society comes in the form of many theses and dissertations produced by his students, as well as works on the Brazilian flora, especially regarding the Compositae and the “campo rupestre”. He played a crucial role in the formation of generations of taxonomists at Unicamp and many other institutions, including the authors of this paper.
João Carmo, André Scatigna, Gustavo Shimizu and André Olmos Simões. 2022. Mitracarpus semirianus (Spermacoceae, Rubiaceae), An overlooked New Species from the “campo rupestre” of Bahia, northeastern Brazil, with notes on Mitracarpus lhotzkyanus. Plant Ecology and Evolution 155(1): 165-177. DOI: 10.5091/plecevo.84548
