https://orcid.org/0000-0001-9215-6851
Figures
Abstract
A new species of Cedrela (Meliaceae) is described and illustrated from recently discovered populations at Rancho del Cielo Biosphere Reserve, Tamaulipas, Mexico. The newly proposed species is morphologically close to C. monroana but differs from the latter in having a shorter habit, thinner terminal twigs, shorter space between leaf pairs along the rachis, shorter petiolules, smaller leaflets, smaller leaflet length-to-width ratio, less numerous secondary leaflet veins, shorter panicles, and yellowish green flowers, broadly obovoid to pyriform fruits, with valves opening at least at an angle of 20 degrees and brown mature capsules with prominent lenticels on valves. We provide a key to the Mexican species of Cedrela including the closely related C. monroana. Latitudinal differences also support the setting aside of the proposed species, which is the most septentrional among its close relatives within Cedrela. Bayesian inference and maximum likelihood analyses of nuclear (ITS) and chloroplast (accD, matK, rbcL, trnH-psbA, psbB-T-N, rpl16, rpoB, rpoC1, trnS-G) DNA sequences of 19 taxa of Cedrela plus 3 from related taxa, place the proposed new species within a clade including Mexican & Central American species. Based on morphological and phylogenetic evidence, we propose the reinstatement of C. saxatilis as a valid species, previously treated as a synonym of C. oaxacensis.
Citation: Gallardo-Yobal SI, Vázquez-García JA, Villalobos-Arámbula AR, Terrazas T, Palacios-Juárez H, Barragán-Reynaga DM, et al. (2025) Integrative taxonomy of Cedrela (Meliaceae) leads to the recognition of a new species (C. tamaulipana) and the reinstatement of C. saxatilis. PLoS One 20(9): e0329846. https://doi.org/10.1371/journal.pone.0329846
Editor: Faham Khamesipour, Kerman University of Medical Sciences, IRAN, ISLAMIC REPUBLIC OF
Received: March 12, 2025; Accepted: July 22, 2025; Published: September 17, 2025
Copyright: © 2025 Gallardo-Yobal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: Chloroplast DNA sequences for Cedrela tamaulipana and Cedrela odorata are available at NCBI GenBank (https://www.ncbi.nlm.nih.gov/genbank/) with following accession numbers: MT877011 to MT877013, OR230464 to OR230485, PP754873 to PP754876. Nuclear DNA ITS sequences for the same species are available in GenBank as PP752068 and PP752069.
Funding: The author(s) received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Cedrela P. Browne is a New World genus of the tribe Cedreleae DC. (Meliaceae, Sapindales) [1] consisting of 21 species distributed from northeastern Mexico to northern Argentina and Paraguay [2–10]. The sister genus of Cedrela, Toona (Endl.) M. Roem., exhibits a Paleotropical distribution, with only five species in India, Indo-China, Malesia, and Australasia [11,12]. Cedreleae and its two genera are well characterized morphologically, and molecular phylogenetic analyses support the monophyly of the tribe [13–15], whose geographic origin, based on fossil evidence, is inferred to be in the Northern Hemisphere [5,6,16].
Cedrela appears in the fossil record of temperate North America from the Early Eocene up to the Middle Miocene, but it became extinct there in the late Miocene [6]. Phylogenetic and biogeographical studies of Cedrela are important for understanding current patterns and processes of diversity within the genus; however, much of this diversity still awaits to be discovered and described. A correct taxonomic identification of sampled individuals is essential for a scientifically sound interpretation of phylogenetic and biogeographic reconstructions, but also to appropriately inform management and conservation strategies, especially for economically important trees like Cedrela [7,17].
The taxonomy of Cedrela is far from complete and the number of new taxa is expected to increase. Four new cryptic species within the C. odorata complex are described in the monograph of Cedrela by Pennington & Muellner [7]. Likewise, four other species were recently described [8–10,18]. Cavers et al. [3] and Finch et al. [19] also report cryptic species within the C. odorata complex in Central and South America.
Widely distributed species often result in polyphyletic groups, entailing several cryptic species, partly due to the influence of environmental and geographical factors as drivers on diversification [3]. For instance, molecular data [5] do not support the traditional concept [20] for C. odorata L. as a widely distributed species from northern Mexico to southern Brazil and the Caribbean [7,21]. Some populations of C. odorata display morphological differentiation in less conspicuous characters such as seeds and seedlings, which are used to subdivide the species [22]. An integrative approach that includes all possible sources of informative characters is necessary to reveal the additional cryptic diversity within the genus. Further fieldwork and additional molecular sampling are also needed to test the species identity of numerous populations within the C. odorata species complex beyond the Caribbean region.
In Mexico, there are seven known species of Cedrela: four endemic species (C. discolor S.F. Blake from Durango in northwestern Mexico, C. dugesii S. Wats. from western Mexico, C. saxatilis Rose and C. oaxacensis C. DC. & Rose from southern Mexico), and three species with a broad distribution (C. salvadorensis Standl. and C. tonduzii C. DC., both mostly confined to Mesoamerica, and C. odorata s. str. from Mexico to the Caribbean region) (Table 1).
Using an integrative approach based on morphological, anatomical, and ecological data, here we describe a new species of Cedrela from eastern Mexico, endemic to the northernmost distributional range of the genus. Additionally, we use nuclear and cpDNA sequences to assess its phylogenetic position. Based on morphological and phylogenetic evidence, we propose the reinstatement of C. saxatilis as a valid species, previously treated as a synonym of C. oaxacensis.
Materials & methods
Field work and populations studied
Access to the field sites and sampling was granted by the Municipal Authority of Gómez Farías, Tamaulipas, Mexico (permits PM/SA/02/2022 and PM/SA/164/2022). The populations studied occur in the Sierra de Gómez Farías, in Tamaulipas, Mexico.
Field work was conducted between February and August from 2018 to 2023, coinciding with the flowering period of the species. A total of 48 individuals of Cedrela sp. were recorded within the El Cielo Biosphere Reserve. The highest concentration of specimens was found in the type locality population, where 23 adult trees were identified.
Morphology
The morphological description and the illustrations were based on both fresh and herbarium material (Table 1). Numerous extra specimens of Mesoamerican Cedrela spp. were examined in major pertinent herbaria (B, BM, EAP, F, IBUG, K, LAGU, MEXU, MO, OSU, NY, UAT, US, USF), seeking a broad understanding of all closely related taxa as well as dozens of specimens of the geographically close and widely distributed Cedrela odorata (including Berrones-Morales 22 & 23, at IBUG, for this study). Electronic images of the type material of all eight taxa from Table 1 were consulted at the websites of some of the aforementioned herbaria. The herbarium acronyms follow Thiers [23]. Measurement of morphological characters for the new species was performed on 12 adult trees, of which 6 had floral structures.
Leaf description and terminology of reproductive structures follow Radford et al. [24] and Pennington & Muellner [7]. The diagnosis and comparative Table 1 primarily involved diagnostic characters following Pennington & Muellner [7]. We added some novel characters because they showed variability and proved to be of diagnostic value (non-overlapping), at least between two species or even among several closely related taxa; namely: (1) leaflet length to width ratio, (2) petiolule length, (3) panicle length, (4) visual flower density, (5) angle of primary branches in panicles, (6) flower color and (7) thickness of capsule valves.
Using several non-overlapping diagnostic characters (Table 1), we document substantial morphological differences between Cedrela sp. from Tamaulipas and eight Cedrela species from Mexico and Central America, including the widely distributed C. odorata also occurring close to the type locality of the proposed new Cedrela species described here.
Wood anatomical comparison
Two wood samples of Cedrela from cut-down adult trees were obtained for anatomical analysis; one from the “red cedar” initially treated as C. aff. odorata (Gallardo-Yobal 9, UAT)— which after the interpretation of results turned out to be C. odorata s. str.—and another one from the locally named “black cedar”, also called “walnut cedar”, Cedrela sp. from Tamaulipas (Gallardo-Yobal 10, UAT); both samples from Rancho El Cielo Biosphere Reserve. Transverse, tangential and radial sections (20 µm thick) were cut with a sliding microtome. The sections were gradually dehydrated with an ethanol concentration gradient (50%, 70%, and 96%), stained with safranin and mounted in temporal slides in glyceryl-water to perform observations. The presented data follow the recommendations of the IAWA Committee [25] and are compared with those from the species of Cedrela available in the database InsideWood [26] as well as a specimen stored as C. odorata from the wood collection of the Institute of Biology, UNAM (catalog number XP-224).
DNA extraction, PCR amplification, and sequencing
Total genomic DNA was extracted from silica-gel dried material (leaf fragments) from the five specimens of Cedrela from Tamaulipas (S1 File), using a modified salt-extraction method with 1% PVP [27]. The nuclear genomic region ITS (internal transcribed spacer), and seven chloroplast genomic regions (accD, matK, rbcL, psbB-T-N, rpl16, trnH-psbA, and trnS-G) were amplified by PCR reactions performed with 1 × KCl reaction buffer, 5 mM MgCl2, 0.2 mM of each dNTP, 0.5 μM of each primer, 0.5 U of Taq polymerase, 0.2 μg/μL of Bovine Serum Albumine (BSA), and 1 μL of DNA template (10 ng/μL) in a 50 μL final volume. For the ITS we used primers F1-ITS and R1-ITS [28]; for the rbcL genomic region, we used primers rbcLa-F [29] and rbcLa-R [30]; for trnH-psbA, primers psbA3_f [31] and trnHf_05 [32]; for matK, primers XF [33] and MALVR1 [34]; for psbB-T-N, primers psbH and psb_B [35]; for accD, primers accD-IGSF and psaI-IGSR [36]; for trnS-G, primers trnSGF and trnSGR [37]; for rpl16, primers rpl6_1F and rpl16_3R [37]. PCR cycles were carried out using the following thermal profile for rbcL and trnH-psbA: 95 °C for 5 min, 35 cycles at 95 °C for 48 s, 55 °C for 30 s, 72 °C for 30 s, and a final extension at 72 °C for 10 min. For the matK region: 94 °C for 4 min, then 35 cycles at 94 °C for 1 min, 48 °C for 1 min, 72 °C for 1 min, and a final extension at 72 °C for 10 min. For the psbB-T-N, accD, trnS-G, and rpl16 regions: 94 °C for 4 min, then 34 cycles at 94 °C for 1 min, 52 °C for 1.5 min, 72 °C for 2 min, and a final extension at 72 °C for 10 min. PCR products were cleaned using Illustra GFX columns (GE Healthcare); purified products were sent to the University of Arizona Genetics Core (UAGC) for DNA sequencing. Contigs from forward and reverse reads were assembled and annotated in Geneious 8.1.9 (Biomatters Ltd., Auckland, New Zealand) and deposited in GenBank (see S1 File for accession numbers).
GenBank survey and sequence alignment
To assess the phylogenetic placement of Cedrela sp. from Tamaulipas, we retrieved DNA sequences from GenBank representative of the tribe Cedreleae, also including sequences from more distantly related genera; cpDNA sequences from three coding (accD, matK, rbcL) and six non-coding (trnH-psbA, psbB-T-N, rpl16, rpoB, rpoC1, trnS-G) regions, plus one nuclear locus (ITS) (S1 File), were used for subsequent phylogenetic analyses. The newly obtained sequences of Cedrela sp. from Tamaulipas and C. odorata were aligned along with GenBank sequences, assembling a final dataset that included 28 samples of Cedrela from Mexico, Central and South America and one sample of the sister genus Toona. Additionally, sequences from two Meliaceae taxa outside of Cedreleae were included as outgroup taxa to root the tree; Azadirachta indica and Swietenia macrophylla. Sequences for each genomic region were aligned using the MAFFT algorithm [38] with default parameters, and alignments for individual loci were concatenated into a single data matrix.
Molecular phylogenetic analyses
A Bayesian phylogenetic analysis (BI) was performed on the full dataset of concatenated sequences using MrBayes 3.2.6 [39]. Two simultaneous runs (each with four chains) of the Metropolis-coupled Markov chain Monte Carlo (MCMC) were carried out for 5 million generations with a sampling frequency of parameters every 500th generation. The best-fit models were selected independently for each partition according to the Akaike information criterion with jModelTest2 [40]. Stationarity and convergence of the Markov chains were assessed by checking the variation of log-likelihood values throughout the run generations with Tracer 1.7.2. [41]. The first 2500 sampled trees were excluded from the analysis as a burn-in; the remaining trees were used to generate a 50% majority rule consensus tree. Additionally, Maximum Likelihood (ML) analyses were performed with IQ-TREE 2.3.6. [42] using the -m TESTMERGE option to find the best-fit partitioning scheme by possibly merging partitions to reduce overparameterization. Support values for the inferred groups were estimated from 1000 ultrafast bootstrap replicates [43]. The tree from the BI analysis was used as the final figure, including support values for the nodes from both BI and ML analyses using the R library “ggtree” [44].
Nomenclature
The electronic version of this article in Portable Document Format (PDF) in a work with an ISSN or ISBN will represent a published work according to the International Code of Nomenclature for algae, fungi, and plants, and hence the new names contained in the electronic publication of a PLOS ONE article are effectively published under that Code from the electronic edition alone, so there is no longer any need to provide printed copies.
In addition, new names contained in this work have been submitted to IPNI, from where they will be made available to the Global Names Index. The IPNI LSIDs can be resolved and the associated information viewed through any standard web browser by appending the LSID contained in this publication to the prefix http://ipni.org/. The online version of this work is archived and available from the following digital repositories PubMed Central, LOCKSS.
Results
Cedrela sp. from Tamaulipas was first collected at Rancho El Cielo Biosphere Reserve in May 2018. A closer examination revealed substantial qualitative and quantitative morphological differences with other closely related species (Table 1). Additionally, anatomical data and phylogenetic analyses of chloroplast and nuclear DNA sequences, allowed us to conclude that we were dealing with an undescribed species of Cedrela from the northeastern Sierra Madre Oriental biogeographic province in México.
Taxonomic treatment
Cedrela tamaulipana A.Vázquez & Gallardo-Yobal sp. nov. [urn:lsid:ipni.org:names:________] Type: MEXICO. Tamaulipas: Municipio de Gómez Farías, Alta Cima, 6.81 km al Noroeste de Gómez Farías y 1.08 km al Oeste de Alta Cima, on karstic topography with subdeciduous forest, 1042 m in elevation, 23°4′48.34″ N, 99°9′44.28″ W, 01 May 2018 (fl, fr), M. Berrones-Morales 1 (Holotype: UAT [UAT-22868], isotype: IBUG [IBUG-214565]). — Figs 1–6.
Diagnosis.
Cedrela tamaulipana shares with C. monroana T.D. Penn. a similar leaf length (petiole + rachis), leaflet shape and glabrous leaf condition, number of leaflet pairs, leaflet apex, lax inflorescence, and fruit size. However, it differs from the latter in having a shorter height (up to 9.0–10.0 vs. up to 23.0 m); thinner young branches (4.0–5.0 vs. 10.0–15.0 mm); shorter space between leaflet pairs along the rachis (3.3–4.3 vs. 5.5–6.0 cm); shorter petiolules (1.0–2.0 vs. 3.0–9.0 mm); smaller leaflets (7.0 × 3.6–11.3 × 4.7 vs. 14.0 × 5.0–19.0 × 6.9 cm); smaller leaflet length-to-width ratio (1.7–2.4 vs. 2.7–2.8); less numerous secondary leaflet veins (9–11 vs. 15–19); shorter panicles (27.0–35.0 vs. 40.0–60.0 cm); petals green-yellowish vs. pale pinkish to deep reddish-purple; fruits broadly obovoid to pyriform vs. ellipsoid to slightly obovoid; mature capsules brown vs. purple; capsule with thicker valves (4.0–5.0 vs. 1.0–1.5 mm); dehiscing valves splitting at an angle of >20 degrees with prominent lenticels vs. barely splitting at an angle of <20 degrees, with inconspicuous lenticels.
Cedrela tamaulipana (red circles) and C. odorata (turquoise circles). Source of data: field observations and GBIF [46]; Natural Earth [47] for administrative boundaries, shaded relief, and water. Biogeographical provinces were redrawn after Morrone [48]. The boundaries of El Cielo natural protected area are based on the official declaration by the state government of Tamaulipas [49]. Figure is similar but not identical to the original peer-reviewed image and is therefore for illustrative purposes only.
A–B. Dissected flowers. C. Cymule. D. branch with inflorescence during development, before anthesis. E. Leaf. F. Seed. G. Capsule. H. Infructescence. Illustration by Daniel Barba.
A–B. Tree of C. tamaulipana with tortuous branching. C. Detail of its corky bark.
Branch with leaves and capsules; type material.
A. Inflorescence. B. Flowers with barely exert stigmas. C. Dissected developing flower. D. Dissected nearly mature flower. E. Mature flower with sepals and petals; one petal removed. F. Mature flower with all five petals removed.
A, D. Leaves. B, E. Ripen fruits, closed and open. C, F. Inflorescences. Source: A, C, Martínez 265 (vouchers at B, LAGU); B, Galan 6026 (voucher at LAGU), Monro, Monterossa & Carballo 3789 (voucher at BM); D–F, Berrones-Morales 1 (syntype material at IBUG). Scale bar of 10 cm applies to A, C–D, F and of 1 cm to B, F.
Description.
Tree 9.0–10.0 m tall, 0.2–1.0 m DBH; young branches 4.0–5.0 mm in diameter, smooth, pale buff, with some elongate lenticels, glabrous. Leaves paripinnate, 40.0–60.0 cm long, glabrous; petioles 7.0–9.0 cm long, greenish in juvenile leaves, glabrous; leaflets 6–9 pairs, opposite, 7.0 × 3.6–11.3 × 4.7 cm, length-to-width ratio 1.7–2.4, elliptic to lanceolate, apex acute to acuminate, base asymmetric, glabrous, bright beam, glabrous in the middle nerves, sessile to subsessile; leaflet secondary veins 9–11; rachis 30.0–50.0 cm long; distance between leaflet pairs 3.3–4.3 cm; petiolules 1.0–2.0 mm. Panicles 27.0–35.0 cm long, lax, angle of primary branches ca. 45 degrees. Flowers 8.0–9.0 mm long, pentamers; 2.0–2.5 mm long; sepals united 0.5–1.0 mm, irregularly lobed; petals 7.0–8.0 mm long, most of their length at anthesis ½ or ⅓, fused to the androgynophore, oblong, green-yellowish, pubescent. The androgynophore is columnar, 3.0–4.0 × 1.0–1.2 mm, 5-sided; stamens 3.0–3.5 mm long, glabrous, with anthers 1 mm long; ovaries 1.1–1.3 mm long, penta-lobed; styles 1.5–2.0 mm long; stigmas capitate, 1.0–1.3 mm wide. Fruits 3.0–3.5 × 1.5–1.8 cm, broadly obovoid to pyriform; central column 7.0–9.0 mm in diameter, with sharp or truncated apex, pericarps 4.0–5.0 mm thick with few prominent ocher lenticels regularly distributed throughout the upper half distal surface, capsule valves 4.0–5.0 mm thick, curved inward, brown, with prominent lenticels. Seeds 2.5–2.7 cm long, wings 1.5–1.8 cm, non-translucent and reddish-brown.
Distribution, habitat and phenology.
Cedrela tamaulipana is only known from El Cielo Biosphere Reserve, Municipality of Gómez Farías, Tamaulipas, Mexico. It occurs along an elevational gradient (300–1100 m) from tropical subdeciduous forest to oak-forest with cloud forest elements. Flowering occurs from May to June and fruiting from July to August.
Eponymy and ethnobotany.
The species is named after the northeastern Mexican state of Tamaulipas, where the type locality is located at El Cielo Biosphere Reserve. C. tamaulipana is locally known as “cedro negro” (black cedar) or “cedro nogal” (walnut cedar) due to its dark wood color (Fig 7), peculiar tree structure and shape of its leaves, which resemble a walnut.
Photographs by Sergio Ignacio Gallardo-Yobal.
Ecologically, Cedrela tamaulipana thrives at higher latitudes than C. monroana, 23°00′–23°10′N vs. 13°35′–13°40′ and its flowering phenology occurs from May to June vs. from August to October. Additionally, Cedrela tamaulipana differs from Cedrela saxatilis, in having shorter petiolules 1.0–2.0 vs. 2.5–5.0 mm, leaflets elliptic to lanceolate vs. broadly lanceolate; fewer secondary veins (9–11 vs. 15–16), more inclined angle, in degrees, of panicle branches (45 and upward vs. 30–40 and downward); flowers green-yellowish vs. purplish; and longer fruits 3.0–3.5 vs. 2.0 cm. Ecologically, Cedrela tamaulipana thrives at higher latitudes than C. saxatilis (23°00’–23°10’N vs. ca. 16°–19° N), lower elevations (300–1100 vs. 1500–2100 m) and its flowering is from May to June vs. September.
Additional specimens examined (paratypes).—MEXICO. Tamaulipas: Municipality of Gómez Farias, 5 km NE 350 m in elevation, 1 May 2019, Gallardo-Yobal 145 (UAT-22998!); same location, 8 November 2022 Berrones-Morales 26 (IBUG- 217371), Berrones-Morales 27 (IBUG-217372).
Proposal to rehabilitate the name Cedrela saxatilis
Cedrela saxatilis has consistently been treated as a synonym of C. oaxacensis [7,50]. Here we propose the validity of C. saxatilis as a good species in its own merit, based on morphological and phylogenetic differences between these species; C. saxatilis differs from C. oaxacensis in: (1) having wider leaflets 5.0–6.0 vs. 3.0–4.5 cm; (2) higher leaflet length to width ratio 2.2–2.3 vs. 1.7–2.1; (3) very slightly pubescent leaves vs. abaxially pale tomentose or villose; (4) shorter capsules 2.0 vs. 3.5–4.0 cm; (5) pendulous capsules vs. erect; and (6) lenticels on capsule valves absent vs. present. We found that the sample Beitel s.n. (OSC) included in our study, morphologically matched the type material of C. saxatilis, Rose & Painter 6950 (US) (Table 1). Furthermore, in our inferred phylogeny, this sample was not recovered within the clade including C. oaxacensis and C. dugesii (Fig 8).
Nodes are annotated with posterior probability (left) and bootstrap support values (right). Dots indicate well-supported nodes from BI (PP > 0.9). The scale bar represents the number of nucleotide substitutions per site. The letter “C.” in taxon names is an abbreviation for Cedrela.
Key to the Mexican species of Cedrela and the closely related C. monroana
- 1a. Capsules ≥ 5 cm long … 2
- 2a. Trees up to 15 m, flowering leafless; inflorescence lateral on old wood, leaves including petiole 40.0–70.0 cm long; leaflet length to width ratio 2.5–2.8; secondary veins 15–20, panicle branches at 30–45 degrees, capsules 8.0–14.0 cm (W, central and SE Mexico to Costa Rica) … C. salvadorensis
- 2b. Trees up to 50 m, flowering when in leaf; inflorescence terminal; leaves including petiole 15.0–25.0 cm long; leaflet length to width ratio 1.8–1.9; secondary veins 5–11, panicle branches at ≈90 degrees, capsules 5.0–8.0 cm (S Mexico to W Panama) … C. tonduzii
- 1b. Capsules < 5 cm long … 3
- 3a. Lower leaflet surface pubescent to tomentose or with minute appressed hairs in the interstice of veins … 4
- 4a. Leaflets discolorous, abaxially appressed puberulous, domatia absent, flowers in dense clusters (NW Mexico) … C. discolor
- 4b. Leaflets not discolorous, abaxially pubescent to tomentose, domatia hair-filled, flowers in lax clusters (S. Mexico) … C. oaxacensis
- 3b. Lower leaflet surface essentially glabrous or rarely puberulous … 5
- 5a. Domatia present … 6
- 6a. Trees 10–15 m; leaflet length to width ratio 2.7–2.8, leaflets ovate to ovate-triangular and apex long acuminate, capsules with inconspicuous lenticels (central Mexico) … C. dugesii
- 6b. Trees 20–40 m; leaflet length to width ratio 3.2–3.3, leaflets lanceolate to oblong-lanceolate and apex short acuminate, capsules with evident white lenticels (Mexico, Central America and the Caribbean) … C. odorata
- 5b. Domatia absent … 7
- 7a. Petiolules 1–2 mm, secondary veins 9–11, leaflets elliptic to lanceolate, flowers green-yellowish (NE Mexico) … C. tamaulipana
- 7b. Petiolules 2.5–9 mm, secondary veins 15–19, leaflets broadly lanceolate, flowers pinkish to reddish-purple … 8
- 8a. Trees up to 23 m, bark fissured, obscure grayish-brown, leaves including petiole 45.0–55.0 cm long, panicles 40.0–60.0 cm long, panicle branches at ≈45–90 degrees, capsules 3.5–4.0 cm long (Guatemala, El Salvador) … C. monroana
- 8b. Trees 4–7 m, bark smooth and reddish, leaves including petiole 20–40.0 cm long, panicles ≥30 cm long, panicle branches reflexed at 30–40 degrees, capsules 2.0 cm long (S Mexico) … C. saxatilis
- 5a. Domatia present … 6
- 3a. Lower leaflet surface pubescent to tomentose or with minute appressed hairs in the interstice of veins … 4
Wood anatomy
Cedrela tamaulipana has distinct growth rings, marked by vessel diameter differences and marginal parenchyma (Fig 9A, C, E). Wood is semi-ring-porous; the tangential diameter of earlywood vessels is 168.20 µm and latewood 59.33 µm, arranged as solitary or in radial groups of 2–3 and circular in outline (Fig 9B, D); perforate plates are simple and inter vessel pits alternate, polygonal (Fig 10E). Fibers are non-septate with minutely simple pits, diameter 17.66 µm, and 3.32 µm in wall thickness. Apotracheal parenchyma is diffuse, paratracheal scanty or vasicentric, and marginal have narrow bands up to 4 cells wide, strands commonly of 4–6 cells (Fig 10C). Uniseriate rays are rare, multiseriate rays are 2–4-seriate, most common 3-seriate (Fig 10A–D), 340.29 µm high and 45.56 µm wide, with procumbent cells and marginal cells upright or sometimes squared. Dark-staining deposits are present in several vessel lumina, most fibers and ray cells (Figs 9, 10). Prismatic crystals are deposited in non-chambered axial parenchyma cells and rays (Fig 10B).
Cedrela tamaulipana (A–E) vs. C. odorata (F–J). A–E. Magnification used for images of the first row was 4 × , for the 2nd and 3rd rows 10× and for the 4th and 5th rows 40 × . Photographs by Hilda Palacios.
Cedrela tamaulipana (A–E) vs. C. odorata (F–J). Magnification used for images of the first row was 4 × , for the 2nd and 3rd rows 10× and for the 4th and 5th rows 40 × . Photographs by Hilda Palacios.
Molecular phylogenetic analysis
The final matrix of concatenated sequences from 10 genomic regions comprised 7072 aligned base pairs, of which 570 were variable sites, and 199 phylogenetically informative. The nucleotide substitution models that best fit each DNA partition, and the summary statistics of DNA sequences, are presented in Table 2.
Both BI and ML phylogenetic analyses, essentially recovered the same tree topology, except for different support values for some groups. Cedrela splits into two well-supported clades; clade A (PP = 1.0, BS = 95%) which includes species from Mexico, Costa Rica and El Salvador, and clade B (PP = 1.0, BS = 100%) including samples from Cuba, Mexico and the rest of the Central and South American species (Fig 8). Both BI and ML analyses confirm the monophyletic nature of Cedrela (PP = 0.89, BS = 82%) with Toona recovered as a sister lineage.
The species described here as C. tamaulipana sp. nov. is placed within clade A, as closely related to C. dugesii, C. monroana, C. oaxacensis, and C. saxatilis (voucher Beitel s.n.). Although the relationships among these species were not fully resolved, C. tamaulipana appears as a genetically distinct group (PP = 0.81, BS = 86%) separated from the other species (Fig 8). Cedrela salvadorensis and C. tonduzii are recovered as more divergent taxa within this clade A.
Within clade B, Cedrela odorata s. str. (voucher Villacorta and Berendsohn 271 from El Salvador) is placed as a sister taxon to C. odorata from Tamaulipas, Mexico (vouchers Berrones-Morales 22 and 23) and Cuba (voucher Thuenen-ID CEODO_205_2, GenBank accession MG724915.1); all these samples were recovered as a more divergent and well-supported (PP = 1.0, BS = 100%) monophyletic group within clade B. The South American species (C. angustigolia DC., C. balansae C. DC., C. fissilis Vell., C. kuelapensis T.D. Penn. & Daza, C. molinensis T.D. Penn. & Reynel, C. montana Moritz ex Turcz., C. nebulosa T.D. Penn. & Daza, C. saltensis M.A. Zapater & del Castillo, C. weberbaueri Harms and Cedrela sp. voucher Neill et al. 6230) and one species from the Antilles (C. cubensis Bisse) (voucher Cuba excursion 462, S1 File), were recovered as a well-supported monophyletic group (PP = 1.0, BS = 96%). The relationships among South American species were poorly resolved and the results from BI and ML analyses were slightly different, with low support values for the internal nodes.
Discussion
Evidence from an integrative approach, involving morphological, ecological and molecular data, support the recognition of Cedrela tamaulipana as a new species. Likewise, based on morphological and phylogenetic evidence we propose the validity of C. saxatilis as a distinct species.
Morphology
Cedrela tamaulipana has a tortuous trunk, with branches in a zigzag pattern, unlike most species of Cedrela [7]. It shares the short habit (<15 m tall) of C. dugesii and C. oaxacensis, however, its bark is blackish, differing from those of C. dugesii (gray) and C. oaxacensis (reddish gray). It also differs from C. oaxacensis in having a corky and deeply fissured bark, distinct wood growth rings, panicle branches at an angle of ca. 45 degrees, flowers green-yellowish, fruit broadly obovoid to pyriform and thicker, strongly curved carpel valves [51,52].
Cedrela saxatilis has been treated as a synonym of C. oaxacensis [7,50], however, based on the morphological similarities found between the sample initially labeled in our study as C. aff. odorata NYBG accession 683/89 and the type material of C. saxatilis, along with our phylogenetic results, we agree with Joseph Nelson Rose that C. saxatilis is a distinct species. When naming the latter, Rose [53] had a relatively good understanding of the taxonomy of Mexican Cedrela species and rightfully contrasted C. saxatilis against the other glabrous species, and not against the abaxially pubescent C. oaxacensis. It is also noteworthy to mention that Finch et al. [54], in their phylogenetic analysis using whole chloroplast genomes, found that such a sample (labeled in their study as C. odorata CEOD-NYBG) represents a more divergent taxon, sister to the other Cedrela species included in their analysis. We have also recovered it as a divergent taxon, not grouped with any other closely related species within clade A (Fig 8); particularly, it was not recovered within the clade including C. oaxacensis + C. dugesii.
Wood anatomy
The new species shares most wood characteristics with the other Cedrela species but seems to be unique in the number of dark-staining deposits in fiber lumina as well as in parenchyma and rays (Figs 9, 10). C. tamaulipana, like most species of Cedrela, has ring or semiring porous wood; other species like C. montana have diffuse-porous wood. Cedrela tamaulipana differs from C. odorata in having narrower earlywood vessel diameter (168.20 vs. 255.21 µm), narrower latewood vessel diameter (59.33 vs. 120.52 µm), narrower fiber diameter (17.66 vs. 26.22 µm) with thinner walls (3.32 vs. 4.59 µm). Although strong cell size differences for vessels and fibers were detected between C. tamaulipana and C. odorata, comparisons with other species are needed; because quantitative data are difficult to obtain from references, especially for earlywood and latewood vessel diameter and fiber wall thickness.
Additionally, the prismatic crystals in non-chambered cells are shared with C. odorata and C. montana and different in the chambered ones compared to C. salvadorensis and C. tubiflora; these crystals are lacking in C. balansae. C. tamaulipana showed 1–3-seriate rays, similar to C. balansae, C. odorata, C. salvadorensis and C. tubiflora [25], but wider 2–6 seriate rays are found in C. montana [55].
Molecular phylogenetic analysis
Results from phylogenetic analyses confirm that C. tamaulipana represents a genetically distinct taxon that belongs to the clade of Mexican and Central American species of Cedrela (Fig 8, clade A). Similar to the results of Muellner et al. [6] and Koecke et al. [5], our phylogeny shows that the genus comprises two monophyletic groups with distinct geographical affinity. Clade B mainly includes species from South America, with some early-diverged lineages from Central America and the Antilles. In contrast, clade A includes species from Mexico and Central America, where C. tamaulipana is placed. Interestingly, despite the sympatry of C. odorata and C. tamaulipana, the latter is recovered within clade A as a monophyletic group (PP = 0.81, BS = 86), reflecting its phylogenetic distinctiveness (Fig 8). Hence, besides the morphological and ecological differences, the molecular evidence also supports that C. tamaulipana represents a distinct taxon.
The analyzed sequence data could mostly resolve the relationships among members of clade B, although with low support for some of them. Similarly, Koecke et al. [5], using a matrix of concatenated sequences from nuclear and cpDNA, obtained a lack of support for several relationships among members of this clade (clade II in their study). For instance, they recover C. odorata s. str. as a divergent lineage sister to samples from Central and South America, all included in a recently evolved clade but with a very low support value (PP = 0.58). Pennington & Muellner [7], combining nuclear and plastid data, recovered C. odorata s. str. as a sister lineage to samples only from South America but also with a very low support value (PP = 0.44). Similarly, Muellner et al. [6] recovered C. odorata s. str. from Central America as a sister group to all Southern American species, except C. angustifolia and C. montana, which formed a distinct and more basal clade. We recovered C. odorata from Tamaulipas, Cuba, and El Salvador as an early diverged clade (PP = 1.0, BS = 100%) within clade B (PP = 1.0, BS = 100%), sister to a clade including all sampled South American species, plus C. cubensis from Cuba (Fig 8). Our result is compatible with that of Finch et al. [54], who used whole chloroplast genome sequences from Cedrela and closely related genera. The five species of Cedrela included in their study were recovered as a monophyletic group, which were also recovered as monophyletic in our study within clade B, except for their sample labeled as C. odorata CEOD-NYBG, which corresponds to C. saxatilis Beitel s.n. in our study, placed within clade A (Fig 8). Similarly, Finch et al. [54] recovered this sample as a more divergent taxon, sister to all of the Cedrela species they included.
One possible cryptic species is represented by the sample of Cedrela sp. from Ecuador (Neill et al. 6230); even though this specimen was repeatedly determined as C. odorata, by T. D. Pennington, our phylogenetic analyses place it with high support values (PP = 1.0, BS = 100%) as a sister taxon to C. saltensis and C. nebulosa, from Argentina and Peru, respectively. This relationship was also found by Muellner et al. [6]; hence this taxon requires a closer taxonomic revision.
Within clade A, the earliest divergent species was C. salvadorensis, in accordance with the results obtained by Muellner et al. [6] and Pennington & Muellner [7]. The close relationship between C. dugesii and C. oaxacensis (PP = 0.84, BS = 83%) is also in agreement with the results of Muellner et al. [6], Pennington & Muellner [7], and Cavers et al. [3]. However, Koecke et al. [5] recovered C. dugesii as a sister taxon to C. monroana, and C. oaxacensis as a sister taxon to C. salvadorensis, although the latter relationship with very low support (PP = 0.6). In contrast, we recovered C. monroana as an early divergent taxon within the five-species subclade (PP = 0.95, BS = 54%) including C. dugesii, C. oaxacensis, C. tamaulipana and Cedrela saxatilis (Fig 8, clade A). Contrary to previous studies [6,7], we recovered C. tonduzii in a basal position within clade A, with a relatively high posterior probability for the group (PP = 0.91) but with a contrasting low bootstrap value (BS = 53%).
Interestingly, we found that C. tamaulipana trnH-psbA sequence, corresponds to the haplotype H21 reported by Koecke [56] for C. dugesii (German et al. 450) and C. monroana (Monroe & Alexander 308). Likewise, there is only one nucleotide difference between the haplotype H21 and the haplotype for the same locus from the sample of C. saxatilis from Oaxaca (Beitel s.n.). According to Koecke [56], this haplotype is restricted to Mexico and Central America, thus suggesting a shared evolutionary history for these taxa, also supported by our phylogenetic results which recovered clade A as monophyletic.
Ecology and distribution pattern
Species of Cedrela from Mexico and Central America recovered in clade A occur from 8°00’N to 22°14’N of latitude [7], except C. tamaulipana, which has the most septentrional distribution; between 23°00’N and 23°10’N (Table 1). Cedrela tamaulipana is confined to the Sierra Madre Oriental, and thus, it is latitudinally isolated from all other species in clade A, including the geographically close species C. duguesii, which occurs in the Chihuahuan Desert, southern Sierra Madre Occidental and the Trans-Mexican Volcanic Belt. Likewise, C. oaxacensis is only found towards the south; in the Balsas Basin, Sierra Madre del Sur and the Pacific Lowlands. On the other hand, the altitudinal range of C. tamaulipana overlaps with some of the Mexican Cedrela species, except with C. duguesii, C. saxatilis, and C. discolor (Table 1) [7]. Southern Cedrela species tend to have a broader altitudinal niche breadth and higher elevations. The habitat of C. tamaulipana (subdeciduous forest), differs from the habitat reported for most of its sister species from clade A, except for the Central American C. monroana, which thrives in a similar habitat. C. duguesii and C. salvadorensis grow in tropical deciduous forests, while C. oaxacensis and C. tonduzii occur mostly in pine-oak forests and the latter occasionally in cloud forests along with species of Liquidambar and Podocarpus [7].
Conclusions
Cedrela tamaulipana is a distinct species based on morphological, molecular and ecological evidence; hence, Cedrela´s diversity, including the here reinstated C. saxatilis, is now updated to 23 species. Within the monophyletic Cedrela, C. tamaulipana belongs to a clade including taxa from Mexico and Central America. Based on morphological and phylogenetic evidence, C. saxatilis represents a distinct taxon, not a synonym of C. oaxacensis. Further taxonomic studies using an integrative approach are required to reveal the expected cryptic diversity of Cedrela in the Neotropics.
Supporting information
S1 File. Appendix 1. GenBank accession numbers, voucher information and geographic origin of Meliaceae samples used in phylogenetic analysis.
https://doi.org/10.1371/journal.pone.0329846.s001
(DOCX)
S2 File. Appendix 2. Selected specimens (Exsiccatae) of Mesoamerican Cedrela.
https://doi.org/10.1371/journal.pone.0329846.s002
(DOCX)
Acknowledgments
We would like to thank the following institutions: Instituto de Ecología Aplicada, Universidad Autónoma de Tamaulipas, Universidad de Guadalajara-CUCBA-CUCSUR (PRO-SNI and p3E programs), PRODEP-SEP and SNI-CONACyT in Mexico. We also thank Daniel Barba for the scientific illustration. To the herbarium curators for facilities provided, especially to Roberto Escobar and Dagoberto Rodríguez from the LAGU herbarium in La Libertad, El Salvador.
References
- 1. Pennington TD, Styles BT. A generic monograph of the Meliaceae. Blumea. 1975;22:419–540.
- 2. Cavers S, Navarro C, Lowe AJ. Chloroplast DNA phylogeography reveals colonization history of a Neotropical tree, Cedrela odorata L., in Mesoamerica. Mol Ecol. 2003;12(6):1451–60. pmid:12755874
- 3. Cavers S, Telford A, Arenal Cruz F, Pérez Castañeda AJ, Valencia R, Navarro C, et al. Cryptic species and phylogeographical structure in the tree Cedrela odorata L. throughout the Neotropics. Journal of Biogeography. 2013;40(4):732–46.
- 4. Heads M. Biogeography and ecology in a pantropical family, the Meliaceae. GBS. 2019;71(suppl.2):335–461.
- 5. Koecke AV, Muellner‐Riehl AN, Pennington TD, Schorr G, Schnitzler J. Niche evolution through time and across continents: The story of Neotropical Cedrela (Meliaceae). American J of Botany. 2013;100(9):1800–10.
- 6. Muellner AN, Pennington TD, Koecke AV, Renner SS. Biogeography of cedrela (meliaceae, sapindales) in central and South america. Am J Bot. 2010;97(3):511–8. pmid:21622412
- 7.
Pennington TD, Muellner AN. A monograph of Cedrela (Meliaceae). Milborne Port, England: Dh Books. 2010.
- 8. Palacios WA, Santiana J, Iglesias J. A new species of Cedrela (Meliaceae) from the eastern flanks of Ecuador. Phytotaxa. 2019;393(1):84.
- 9. Hágsater E, Duarte Salinas J, Jiménez machorro R, Pío-León JF, Millán Otero MG. Epidendrum petacaense, a new species of Orchidaceae from Sinaloa, Mexico. Phytotaxa. 2023;592(2):81–7.
- 10. Villanueva-Tamayo B, Morales-Puentes ME, Cruz OM, Aymard-Corredor GA. A New Species of Cedrela (Meliaceae) from a Colombian Dry Forest and an Updated Key for the Species of the Genus. Harvard Papers in Botany. 2023;28(2).
- 11. Edmonds JM. The potential value of Toona species (Meliaceae) as multipurpose and plantation trees in Southeast Asia. Commonw For Rev. 1993;72:181–6.
- 12.
Mabberley DJ, Pannell CM, Sing AM. Flora Malesiana ser. I Meliaceae. Leiden, Netherlands: Rijksherbarium, Foundation Flora. 1995.
- 13. Muellner AN, Pennington TD, Chase MW. Molecular phylogenetics of Neotropical Cedreleae (mahogany family, Meliaceae) based on nuclear and plastid DNA sequences reveal multiple origins of “Cedrela odorata”. Mol Phylogenet Evol. 2009;52(2):461–9. pmid:19348956
- 14. Muellner AN, Samuel R, Johnson SA, Cheek M, Pennington TD, Chase MW. Molecular phylogenetics of Meliaceae (Sapindales) based on nuclear and plastid DNA sequences. Am J Bot. 2003;90(3):471–80. pmid:21659140
- 15. Muellner AN, Savolainen V, Samuel R, Chase MW. The mahogany family “out-of-Africa”: divergence time estimation, global biogeographic patterns inferred from plastid rbcL DNA sequences, extant, and fossil distribution of diversity. Mol Phylogenet Evol. 2006;40(1):236–50. pmid:16624592
- 16. Muellner-Riehl AN, Rojas-Andrés BM. Biogeography of Neotropical Meliaceae: geological connections, fossil and molecular evidence revisited. Braz J Bot. 2022;45(1):527–43.
- 17. Cavers S, Navarro C, Lowe AJ. A combination of molecular markers identifies evolutionarily significant units in Cedrela odorata L. (Meliaceae) in Costa Rica. Conservation Genetics. 2003;4(5):571–80.
- 18. Köcke AV, Muellner-Riehl AN, Cáceres O, Pennington TD. Cedrela ngobe (Meliaceae), a new species from panama and costa rica. Edinburgh J Bot. 2015;72(2):225–33.
- 19. Finch KN, Jones FA, Cronn RC. Cryptic species diversity in a widespread neotropical tree genus: The case ofCedrela odorata. American J of Botany. 2022;109(10):1622–40.
- 20.
Styles BT. Swietenioideae. In: Pennington TD, Styles T, Taylor DAH. Flora Neotropica Monograph. New York: New York Botanical Garden. 1981. 359–418.
- 21. Villaseñor JL. Checklist of the native vascular plants of México. RevMexBiodiv. 2016;87(3).
- 22. Navarro C, Ward S, Hernández M. The tree Cedrela odorata (Meliaceae): a morphologically subdivided species in Costa Rica. Rev Biol Trop. 2002;50(1):21–9. pmid:12298247
- 23.
Thiers B. The World’s Herbaria 2017: A Summary Report Based on Data from Index Herbariorum. New York: New York Botanical Garden. 2018.
- 24.
Radford AE, Dickison WC, Massey JR, Bell CR. Vascular plant systematics. New York: Harper & Row. 1974.
- 25. IAWA Committee. Iawa list of microscopic features for hardwood identification. IAWA J. 1989;10:219–332.
- 26. Wheeler EA. Inside Wood – A Web resource for hardwood anatomy. IAWA J. 2011;32(2):199–211.
- 27. Aljanabi SM, Martinez I. Universal and rapid salt-extraction of high quality genomic DNA for PCR-based techniques. Nucleic Acids Res. 1997;25(22):4692–3. pmid:9358185
- 28. Muellner AN, Samuel R, Chase MW, Pannell CM, Greger H. Aglaia (Meliaceae): an evaluation of taxonomic concepts based on DNA data and secondary metabolites. Am J Bot. 2005;92(3):534–43. pmid:21652432
- 29. Levin RA, Wagner WL, Hoch PC, Nepokroeff M, Pires JC, Zimmer EA, et al. Family-level relationships of Onagraceae based on chloroplast rbcL and ndhF data. Am J Bot. 2003;90(1):107–15. pmid:21659085
- 30. Kress WJ, Erickson DL. A two-locus global DNA barcode for land plants: the coding rbcL gene complements the non-coding trnH-psbA spacer region. PLoS One. 2007;2(6):e508. pmid:17551588
- 31. Sang T, Crawford DJ, Stuessy TF. Chloroplast DNA phylogeny, reticulate evolution, and biogeography of Paeonia (Paeoniaceae). American J of Botany. 1997;84(8):1120–36.
- 32. Tate JA, Simpson BB. Paraphyly of Tarasa (Malvaceae) and diverse origins of the polyploid species. Syst Bot. 2003;28:723–37.
- 33. Ford CS, Ayres KL, Toomey N, Haider N, Van Alphen Stahl J, Kelly LJ, et al. Selection of candidate coding DNA barcoding regions for use on land plants. Botanical Journal of the Linnean Society. 2009;159(1):1–11.
- 34. Dunning LT, Savolainen V. Broad-scale amplification of matK for DNA barcoding plants, a technical note. Botanical Journal of the Linnean Society. 2010;164(1):1–9.
- 35. Hamilton M. Four primer pairs for the amplification of chloroplast intergenic regions with intraspecific variation. Mol Ecol. 1999;8(3):521–3. pmid:10199016
- 36. Prince LM. Plastid primers for angiosperm phylogenetics and phylogeography. Appl Plant Sci. 2015;3(6):apps.1400085. pmid:26082876
- 37. Shaw J, Lickey EB, Beck JT, Farmer SB, Liu W, Miller J, et al. The tortoise and the hare II: relative utility of 21 noncoding chloroplast DNA sequences for phylogenetic analysis. Am J Bot. 2005;92(1):142–66. pmid:21652394
- 38. Katoh K, Standley DM. MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Mol Biol Evol. 2013;30(4):772–80. pmid:23329690
- 39. Ronquist F, Teslenko M, van der Mark P, Ayres DL, Darling A, Höhna S, et al. MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Syst Biol. 2012;61(3):539–42. pmid:22357727
- 40. Darriba D, Taboada GL, Doallo R, Posada D. jModelTest 2: more models, new heuristics and parallel computing. Nat Methods. 2012;9(8):772. pmid:22847109
- 41. Rambaut A, Drummond AJ, Xie D, Baele G, Suchard MA. Posterior Summarization in Bayesian Phylogenetics Using Tracer 1.7. Syst Biol. 2018;67(5):901–4. pmid:29718447
- 42. Minh BQ, Schmidt HA, Chernomor O, Schrempf D, Woodhams MD, von Haeseler A, et al. IQ-TREE 2: New Models and Efficient Methods for Phylogenetic Inference in the Genomic Era. Mol Biol Evol. 2020;37(5):1530–4. pmid:32011700
- 43. Hoang DT, Chernomor O, von Haeseler A, Minh BQ, Vinh LS. UFBoot2: Improving the Ultrafast Bootstrap Approximation. Mol Biol Evol. 2017;35(2):518–22. pmid:29077904
- 44. Yu G, Smith DK, Zhu H, Guan Y, Lam TT. ggtree: an r package for visualization and annotation of phylogenetic trees with their covariates and other associated data. Methods Ecol Evol. 2017;8(1):28–36.
- 45. Morrone JJ. Biogeographical regionalisation of the Neotropical region. Zootaxa. 2014;3782:1–110. pmid:24871951
- 46.
GBIF.org. GBIF Occurrence data download; n.d. [cited 2021 May 4]. https://doi.org/10.15468/dl.j26tht
- 47.
Natural Earth. Natural Earth: free vector and raster map data at 1:10m, 1:50m, and 1:110m scales, downloadable public comain dataset. n.d. [cited 2025 Jul 24]. https://www.naturalearthdata.com/features/
- 48. Morrone JJ, Escalante T, RodrÍguez-Tapia G. Mexican biogeographic provinces: Map and shapefiles. Zootaxa. 2017;4277(2):277–9. pmid:30308652
- 49. Gobierno de Estado de Tamaulipas. Acuerdo gubernamental por medio del cual se aprueba la actualización del programa de manejo del área ecologica protegida “Reserva del la Biósfera El Cielo”, ubicada en los municipios de Gómez Farías, Llera, Jaumave y Ocampo en el Estado de Tamaulipas, establecida mediante decreto gubernamental publicado el 13 de julio del 1985 (Anexo). Periodico Oficial del Estado de Tamaulipas. 2013;CXXXVIII(44):1–74.
- 50.
Pennington TD, Styles T, Taylor DAH. Meliaceae. New York: New York Botanical Garden. 1981.
- 51.
Calderón de Rzedowski G, Ramírez MT. Familia Meliaceae. Pátzcuaro: Instituto de Ecología. 1993.
- 52.
Germán-Ramírez MT. Meliaceae. Cd. de México: Universidad Nacional Autónoma de México. 2007.
- 53. Rose JN. A new spanish cedar from central mexico. Contr U S Natl Herb. 1905;8:314–5.
- 54. Finch KN, Jones FA, Cronn RC. Genomic resources for the Neotropical tree genus Cedrela (Meliaceae) and its relatives. BMC Genomics. 2019;20(1):58. pmid:30658593
- 55. León HWJ. Anatomía de la madera de 13 especies del orden Sapindales que crecen en el estado Mérida, Venezuela. Acta Botánica Venezuelica. 2006;29:269–96.
- 56.
Koecke AV. Spatio-temporal evolution of Cedrela (Meliaceae). Johann Wolfgang Goethe-Universität Frankfurt am Main. 2015. https://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/year/2015/docId/37674