A new species of Cinnamomum (Lauraceae) from the Bladen Nature Reserve, southern Belize

Abstract A new species in the Lauraceae, Cinnamomum bladenense S.W. Brewer & G.L. Stott, is described from the Bladen Nature Reserve in southern Belize. The new species is similar to Cinnamomum brenesii (Standl.) Kosterm., from which it differs by its much smaller, narrowly-campanulate flowers, its inner tepals glabrous abaxially, its shorter petioles, its minutely sericeous younger twigs, and its abaxial leaf surfaces not glaucous and with prominent secondary venation. A description, preliminary conservation assessment, and photographs of the species as well as a key to and notes on the Cinnamomum of Belize are provided.

Floristic inventories in the Bladen Nature Reserve, Belize, Central America ( Figure 1) from 2012-2014 resulted in the discovery of this species of Lauraceae. Fertile herbarium material collected from the type location was determined to be unique among any of the known species of Cinnamomum by comparing it with type and other herbarium specimens housed at MO, and online at F (http://fm1.fieldmuseum.org/vrrc/), HUH (http://kiki.huh.harvard.edu/databases/specimen_index.html), NY (http://sweetgum. nybg.org/science/vh/), US (http://collections.nmnh.si.edu/search/botany/), and JSTOR Global Plants (https://plants.jstor.org/). This plant is described here as a new species, and a key to and notes on the Cinnamomum of Belize are provided. Images of the holotype and at least one isotype will be available on The Missouri Botanical Garden's electronic database TROPICOS (http://www.tropicos.org). Our examination of recent material of the genus in Belize confirms the presence of Cinnamomum areolatum (Lundell) Kosterm. for the country, as first reported by Standley and Steyermark (1946, as Phoebe areolata Lundell). Diagnosis. Cinnamomum bladenense is morphologically similar to Cinnamomum brenesii (Standl.) Kosterm. from which it differs by its much smaller (c. 2.1 vs. 3 mm long) and campanulate (vs. urceolate) flowers, its inner tepals glabrous abaxially (vs. pubescent), its shorter petioles (< 10 vs. > 10 mm), its moderately and minutely sericeous (vs. tomentose) younger twigs, and its abaxially matte green (vs. light-green glaucous) mature leaves with clearly prominent secondary venation abaxially (vs. venation nearly plane with the lamina).

Cinnamomum bladenense
Description. Tree 25 m tall, 26 cm DBH; bole round and mostly straight, with a low, narrow buttress of irregular-sized planks ( Figure 2). Outer bark smooth, light-tomedium gray with a pinkish cast, occasional eye marks and rings, and lines of inconspicuous lenticels oriented lengthwise. Inner bark pinkish-brown with a moderatelypungent, chemical odor like that of bathroom cleaner (volatile, soapy).
Terminal buds moderately to densely sericeous with yellowish-white hairs. Twigs with slender, parallel, longitudinal grooves & low ridges (striate) to striate-angulate, less frequently laterally compressed and ridged-angulate, thinly to moderately-densely, minutely sericeous with silvery-white to yellowish, straight or weakly curved hairs 0.04-0.20 (0.3) mm long. Leaves alternate, thick-chartaceous to sub-coriaceous, ovate to ovate-elliptic, apex acute to shortly acuminate (rarely obtuse or rounded), base acute; within-branch leaf sizes highly variable, 11-31 mm wide × 35-86 mm long; petioles 3-9 mm, broadly and shallowly canaliculate, minutely sericeous. Venation mostly triplinerved, some subtriplinerved, the basal lateral nerves reaching c. ½ to ⅔ the length of the lamina; secondary veins 6-8; midvein and secondary veins immersed above, higher-order venation minutely impressed; midvein and secondary veins prominent below, higher order venation prominulous or minutely so. Inconspicuous domatia present in the form of barbellate axils of the basal-most pair of secondary veins, plane with the lamina, and usually present in one or two additional axils along the midrib, (rarely absent from a leaf). Laminae adaxially glossy, medium-dark green, glabrescent,
Phenology and reproduction. Phenology data for this species are few; currently, flowering in this species is known to begin with the onset of the dry season, December-January, with fruits developing in January and February. The trees are not known to be fertile below 15 cm DBH and are not fertile every year.
Distribution and ecology. Cinnamomum bladenense is currently known only from fewer than 10 individuals on two limestone ridge-and-knoll systems south of the Bladen branch of the Monkey River, a few km upstream from where the Bladen descends into the coastal plain. This canopy tree species occurs in semi-evergreen forest c. 25 m high on very-well-drained, steep and rocky slopes on Cretaceous limestone. Similar habitat occurs southwest of the type location nearly to the Guatemala border, and northeast of the type location to the southeastern portion of the Cockscomb Basin, along the southeastern foothills of the Maya Mountains.
Preliminary conservation assessment. Population information is too limited to support an assessment of the extinction risk faced by Cinnamomum bladenense, and the category of Data Deficient (DD) is appropriate, according to IUCN (2012) criteria. The known habitat of the species is protected as part of a nature reserve, however anthropogenic fires and illegal logging in the area, including nearby potential habitat, are potential risks to the persistence of this species.

Discussion
Cinnamomum bladenense is unique for the genus in its relatively small flowers (< 2.3 mm from the base of the hypanthium to the apex of the tepals of dried specimens), and for its occurrence in the canopy of relatively tall-canopied (20-35 m) limestone slope forest. It has not been found on the adjacent apices of well-exposed ridges or on exposed rock outcrops, which are comparatively lower-and more opencanopied, much denser, of proportionately smaller-trees, and more unique floristically (Brewer et al. 2003). Limestone forests in the type location and nearby forests of similar vegetation have a high proportion of limestone specialists (Brewer unpubl. data), with soil properties significantly different than nearby soils on volcanic substrata (Winbourne et al. 2016). As far as we know, this new species appears to be unique among Neotropical species, perhaps along with C. salicifolium (Nees) Kosterm. from Mexico, by being associated exclusively with limestone. The latter species has abaxially pubescent tepals persistent in fruit, conspicuous and often dense and/or often spreading indument on the leaves and young twigs, villous filaments abaxially, and occurs in oak-pine forests.
In Lorea-Hernández' (1996) revision of the Neotropical species of Cinnamomum Schaeff., specimens of Brewer & Stott 7529 key to C. brenesii, to which it is most similar (see diagnosis for differences), to C. paratriplinerve Lorea-Hernández (ined.), and, with considerable latitude in interpretation of indument, C. hartmannii (I.M. Johnst.) Kosterm. Cinnamomum brenesii is a Costa Rican and Panamanian species most often collected in disturbed and open habitats such as pastureland, roadsides and trail edges (vs. closed-canopy limestone hill forests). Cinnamomum paratriplinerve differs from the new species in having external tepals glabrous adaxially, entirely turbinate pedicels (at least some) in fruit, hypanthium glabrous inside, and generally conspicuously longer leaves. It also is a species of Costa Rica and Panama in disturbed areas (pastureland, secondary forest) as well as "natural", closed-canopy forest. Cinnamomum hartmannii is a species of northwestern Mexico, in the contact zone between dry, oak temperate forests and semi-deciduous to deciduous tropical forests. It has glabrous filaments, and mainly pinnate leaves villous-tomentose beneath when young, among other differences. All other known Neotropical species differ in one or more significant character states, including persistent or entirely-deciduous tepals, domatia absent or secondary domatia present, domatia of pocket-like depressions below and ampullous above, and indument of spreading to erect hairs.
The three species of Cinnamomum in Belize -C. areolatum (Lundell) Kosterm. C. bladenense S.W. Brewer & G.L. Stott, sp. nov., and C. montanum (Sw.) Bercht. & J. Presl -are easily separated in the field without fertile material. In Belize, C. areolatum is typically a small tree (usually < 10 m, < 10 cm DBH), treelet or colonial treelets/shrubs, on the tops and shoulders of ridges on very acidic and nutrient-poor, igneous substrate in somewhat open and low woody vegetation (woodlands or natural disturbances in low forest), dominated by or with a significant component of Purdiaea belizensis (A.C. Sm. & Standl.) J.L. Thomas, occasionally with Cyrilla racemiflora L. and sedges such as Scleria P.J. Bergius and Rhynchospora Vahl, and/or associated with areas of fire-dependent ferns [e.g., Gleichenella pectinata (Willd.) Ching, Sticherus palmatus (W. Schaffn. ex E. Fourn.) Copel., Dicranopteris flexuosa (Schrad.) Underw.)], and never on alluvium. Its canopy is somewhat scattered along the stem, not confined to the upper portion of the stem, with leaves that are < 5 cm wide, coriaceous to thick coriaceous, the upper surfaces smooth and plane, and the veins inconspicuously impressed above. The leaves have conspicuous, densely-prominulous reticulum beneath, and domatia that are pocket-like below and ampullous above (at least some leaves) in the axils of the basal (or more) secondary veins. Cinnamomum montanum is found in ± closed canopy forest on rich alluvium or on acid substrata, never limestone, and is quite capable of exceeding 10 cm DBH and 20 m in height. It has the largest leaves of the three species, very often ≥ 5 cm wide, with at least some leaves > 10 cm long (often some much longer). It also has conspicuous ampullous and pocket-like domatia; however, its upper surface is not plane but "quilted" (coarsely bullate above, with long concave areas beneath) from the impressed midvein and secondary veins. Cinnamomum bladenense is found only on limestone slopes, has small leaves with short petioles, inconspicuous domatia not ampullous, and is a tree with a tight canopy at the top of the stem, even when small.