Mouriri regeliana Cogn. (1888: 572)

2. Mouriri regeliana Cogn. (1888: 572) View in CoL .

Type: BRAZIL. Without locality, without date [fl.], L. Riedel 1701 (holotype: LE00004244 ; isotypes: BR0000005221196 , K000329643 , LE00004243 , P01168022 , P01168026 , P01168028 ). ( Fig.5 View FIGURE 5 )

= Mouriri bahiensis Morley (1976: 66) . Type: BRAZIL. Bahia: forest 8 km S. Itacaré. Árvore de 20 m de alt. e 10 cm diam., cálice verde, pétalas amarelo-ouro, estames amarelo-claro. October 16, 1968 (fl.), J. Almeida & T.S. Santos 160 (holotype: US00123905; isotypes: CEPEC! [accession no. 4884], MIN1001830, MIN1001831, US 01101171). syn. nov.

Description:—Understory tree up to 25 m high. Bark not seen. Stems with young shoots light-gray, terete. Petioles 2.5–6.0 mm long. Leaf blade chartaceous 4.9–14.0 × 1.6–6.0 cm, elliptic to narrow elliptic or narrow-ovate to lanceolate, apex long or short acuminate or acute, base acute, obtuse or rounded, glabrous in both surfaces, venation not visible or obscure in both surface in sicco, midrib grooved on the adaxial surface, rounded on the abaxial surface. Inflorescences axillary, 1–2 per side, 1–7 flowers per peduncle, 5.5–16.7 mm long to base of farthest pedicel measured along the axes with 2–5 internodes in that length. Bracts present at anthesis, 0.6–2.5 mm long, triangular or deltate, apex acute. Pedicels none or up 0.5 mm long. Flower bud with calyx lobes enclosing 2/3 or less the corolla length, hypanthium plus calyx 4.0– 5.8 mm long, obconic, greenish in vivo, blackish in sicco. Sepals 0.9–2.0 × 1.6–2.2 mm, deltate or widely-ovate, apex acute. Petals yellow in vivo, 3.8–7.0 mm × 2.0–3.0 mm, elliptic to widely-elliptic, apex acute or short-acuminate. Filaments yellow in vivo, the antesepalous ones 3.5–5.0 mm long, the antepetalous ones 5.0– 6.5 mm long. Anthers yellow in vivo, 2.4–4.8 mm long, thecae 1.7–2.5 mm long, dehiscing through an apical pore, gland 0.2–0.6 mm long, 1.7–3.1 mm long from apex of anther when measured from center of gland, cauda 0.5–1.1 mm long from base of anther when measured from base of the gland. Ovary (1–)2-locular, axil placentation, ovules 3–4 per placenta, style 7.5–12.0 mm long. Fruits and seeds unknown.

Selected specimens examined: — BRAZIL. Bahia: Almadina, Marinho 588 (HUEFS); Camacan, Rocha 1146 (CEPEC); Itacaré, Almeida 176 (CEPEC); Piraí do Norte, Vasconcelos 445 (HURB); Ubaitaba, Amorim 437 (CEPEC); Una, Mori 13788 (NY); Uruçuca, Thomas 8488 (CEPEC); Wenceslau Guimarães, Thomas 9362 (NY).

Distribution and habitat: — Mouriri regeliana is endemic to the state of Bahia, Brazil. It grows on the hills and mountains of the Atlantic Coast between 14° S and 16° S. This is an understory species in the Brazilian Atlantic Rain Forest. It may also be found in lowland tropical forests (Tabuleiro forest) ( Fig. 6 View FIGURE 6 ).

Conservation status: —Still as separate species, Mouriri regeliana and M. bahiensis were both categorized as Endangered (EN) in previous official assessments due to their restricted distribution and the decrease and fragmentation of their habitat ( Fernandez & Moraes, 2019; Fernandez & Amorim, 2020). Even after the taxonomic recircumscription proposed here, with the inclusion of M. bahiensis as a synonym of M. regeliana , this species can still be considered Endangered [EN B2ab(i,ii,iii)]. The species has a restricted geographic distribution with an extent of occurrence (EOO) of ca. 11,435.5 km ² and an area of occupancy (AOO) of 56 km ². According to the categories and criteria established by the IUCN (2012), the species would be classified as Vulnerable (VU) due to its limited extent of occurrence. However, it could be also considered Endangered (EN), since its area of occupancy is less than 500 km ². Furthermore, most of the available specimens were collected over 30 years ago in a severely fragmented habitat that is still at risk due to deforestation, with less than one-fourth of the original vegetation remaining ( Table 1 View TABLE 1 ). Only three populations of M. regeliana were found in protected areas out of all the collected specimens. Therefore, we recommend that M. regeliana should be maintained as Endangered [EN B2ab(i,ii,iii)].

Nomenclatural and taxonomic notes: Mouriri bahiensis was described based on a single specimen ( Almeida 160) collected in 1968, at a time when M. regeliana was only known from the type. Interestingly, the type of M. bahiensis was collected in the same locality where another Mouriri would be collected two days later by the same collector ( Almeida 176). Years later, in 1973, this collection was identified as the second known collection of M. regeliana , but its morphology indicated that its distinction from M. bahiensis was not as clear as previously thought ( Morley, 1976). However, Morley (1976) still considered them as distinct species and recognized M. bahiensis because of the leaves with a narrower included angle at the base (45–70° vs. 50–150° in M. regeliana ), as well as a slightly shiny adaxial leaf and the small size, shape, and arrangement of the upper epidermal cells. It would also differ by the greater number of flowers per inflorescence (1–7 flowers vs. 1(–3)- flowers in M. regeliana ), shorter calyx lobes (0.9–1.4 mm vs. 1.4–2.0 mm long), larger petals (6.0–7.0 mm vs. 3.8–4.5 mm long), shorter hypanthium plus calyx (4.0–5.0 mm vs. 4.5–5.8 mm long), and longer anthers (3.6–4.8 mm vs. 2.4–3.4 mm long). Despite these differences, even the author recognized that separating both would be difficult. Recent samples from southern Bahia (Amorim 437) showed that these differences are weak and that one or more characters often overlap. After comparing herborized specimens and original descriptions, associated with the similarity in habitat, we propose that M. bahiensis should be synonymized under M. regeliana . According to Art. 11.4 of ICN (Turland et al., 2017), M. regeliana has priority over M. bahiensis since the first one is the oldest legitimate name.

The type specimen of M. regeliana was collected by Ludwig Riedel in an unspecified locality in Brazil. Due to the current distribution of M. regeliana, Riedel presumably collected this specimen in southern Bahia. This botanist arrived in South Bahia in February 1821 and spent nearly two years conducting botanical research in the region before going to Rio de Janeiro in November 1822 ( Urban, 1906; Moraes, 2012).