Portion of the phylogenomic tree presented in Figure 1 of Gernandt et al. (2025) depicting the taxa commonly regarded as closely related to Pinus pseudostrobus.
CONTENTS
Phylogenomics restructure the Pinus pseudostrobus complex
Beginning with Farjon and Styles (1997), Pinus pseudostrobus was treated as a sort of catchall species for all Mexican pines of subsection Ponderosae that were not clearly assignable to some other species. As a result quite a variety of dissimilar taxa were synonymized under P. pseudostrobus and it became one of the most polymorphic of all the pines. Recent genomic analysis (Gernandt et al. 2025) has greatly clarified the phylogenetic relationship between samples assignable to many putative taxa in the Pinus pseudostrobus group. When these findings are interpreted in terms of observable differences between these taxa in the form of morphology, oleoresins, and biogeography, it becomes clear that the prevailing circumscription of Pinus pseudostrobus makes it a polyphyletic taxon. The phylogenomic evidence indicates P. pseudostrobus is sister to a clade comprised of two other widely-distributed Mexican pines, P. montezumae and P. hartwegii, with this group of three species sister to a group of two other species, P. apulcensis and P. oaxacana. (For the sake of brevity, the first 3 taxa are hereafter referred to as the Pseudostrobus clade and the latter 2 as the Oaxacana clade.) The genomic evidence also supports species recognition for the latter two species, formerly widely treated as synonyms (P. apulcensis) or varieties (P. oaxacana) of P. pseudostrobus. The analysis I present here synthesizes the available evidence in light of this phylogenomic information to describe the reasons for subdividing P. pseudostrobus into three distinct species, while also retaining two infraspecific taxa within P. pseudostrobus. The analysis also brings new information to circumscription of other described taxa traditionally synonymized under P. pseudostrobus.
In 1838 C. T. Hartweg collected a variety of pines in the Trans-Mexican Volcanic Belt. These were duly described by Lindley (1839) as six new species: Pinus hartwegii, P. devoniana, P. russelliana [syn. of P. montezumae, previously described], P. macrophylla [syn. of P. devoniana], P. pseudostrobus, and P. apulcensis. All have since proven to be members of subsection Ponderosae. Lindley's descriptions of P. pseudostrobus and P. apulcensis are relevant to this discussion and are quoted in full below. Hartweg's type specimens of both these taxa have been lost, but were illustrated at the time in Loudon (1842), and Loudon's text and illustrations are reproduced at right.
In 1909 G. R. Shaw published The Pines of Mexico. He described and illustrated here a pine based on Lindley's Pinus apulcensis, which he named Pinus pseudostrobus var. apulcensis. However, he evidently had no direct experience of Lindley's pine, and chose instead to illustrate two cones collected in 1894 by Nelson in Oaxaca, and one collected in the Estado de Mexico by Pringle. He also refers to but does not illustrate "a beautiful cone of this variety from the Cofre de Perote, Vera Cruz, collected by Hahn in 1866, with conspicuous protuberances on all the scales." Shaw's variety is accepted by many later authorities.
Then, in 1945, Maximino Martínez published Las Pinaceas Mexicanas. This is the first comprehensive review of the Mexican pines, with 23 pages of text and illustration devoted to a close review of Pinus pseudostrobus and its infrataxa: P. p. forma protuberans, P. p. var. coatepecensis, P. p. var. apulcensis, P. p. var. estevezii, and P. p. var. oaxacana. Martínez provides copious detail and remains an authoritative source, although some of his names were not validly published. Photographs and illustrations are given for each taxon, along with a long list of collection localities covering the known range of the taxon.
Loock (1951) described P. pseudostrobus f. megacarpa.
Mirov (1958), taking issue with Shaw's work, described P. oaxacana.
Finally, Perry (1987) described P. nubicola from Chiapas, Guatemala, Honduras and El Salvador.
Since 1987, no new taxa have been described in the complex, but a considerable number of publications have reviewed the taxa named above and have variously disposed of them. These authorities are cited below as applicable. The remainder of this analysis describes each of the taxa in the P. pseudostrobus complex and assigns each to species or subspecies rank. The names so used are as follows:
Incertae cedis: Pinus heteromorpha Roezl, Pinus prasina Roezl, Pinus regeliana Roezl, Pinus orizabae Gordon, Pinus pseudostrobus subsp. laubenfelsii (Silba) Silba, Pinus pseudostrobus var. laubenfelsii Silba.
The following table summarizes characteristics of the 6 taxa (excepting the two formae) in the Pinus pseudostrobus complex. The remainder of this document addresses each of these taxa in turn. Of the morphological characters listed in the following table, the clearest separators between P. pseudostrobus and the other taxa concern the texture of the cone scale and the prickle on the umbo. The cone scales on P. pseudostrobus are thin and pliable while on the other taxa they are thick and woody. The prickle on P. pseudostrobus is small and easily deciduous while on the other taxa it is firmly fixed, and in other respects is quite different between the taxa.
Fig. 1887. P. pseudostrobus (Loudon 1842).
Fig. 1888. P. pseudostrobus (Loudon 1842).
This taxon as described by Martínez (1945) remains generally accepted. The issue at hand concerns which taxa are to be segregated from P. pseudostrobus sensu lato, all of which are in the Oaxacana clade. There are two formae, megacarpa and protuberans. The former is discussed below; the latter, which refers to protuberances seen on some cones of P. pseudostrobus, was described by Martínez (1948) and has been accepted by all subsequent authorities.
The following is quoted from Lindley (1839):
"Pinus pseudostrobus; pentaphylla, foliis tenuissimis glaucescentibus, strobilus ovalibus verticillatis horizontalibus; squamis apice rhomboideis pyramidatis erectis rectiusculis linea elevata transversa, seminibus ovalibus ala nigrescente quadruple v. quintuple brevioribus." Or, in English, "Five-leaved, with very thin glaucescent leaves, oval cones whorled horizontally; scales with rhomboid pyramidal apex, erect, straighter, with a raised transverse line, oval seeds with a blackish wing, four or five times as long." He added (in English) "Mr. Hartweg describes this as allied to Pinus Devoniana, but quite distinct and resembling P. Strobus in habit; he found it very common at Anganguco [Angangueo, Michoacán], about 8000 feet [2500 m] above the sea. The leaves are fine and glaucous, like those of the Weymouth Pine. The cones are about four inches [10 cm] long, by an inch and half [3.8 cm] in breadth over the middle."
Lindley (1839) did not designate a type but noted the collection by Hartweg near the mining town of Angangueo, Michoacán. As with P. apulcensis, Hartweg's specimens were later lost. The best description we have of Hartweg's type specimen is two illustrations from Loudon (1842). The illustrations are shown at right; Loudon's description adds slightly to Lindley's, and follows:
"Leaves in fives, very slender, glaucescent. Cones oval, verticillate, horizontal. Scales rhomboidal at apex, pyramidal, erect, straightish, with a transverse elevated line. Seeds oval, four or five times shorter than the blackish wing. (Lindl.) A tree. Mexico, at Anganguco, 8000 ft. [2500 m] above the sea. Height ?. Introduced in 1839, by cones sent home by Hartweg, from which many plants have been raised. ... The leaves are five, and glaucous like those of the Weymouth pine; but the cones differ in being thickened at the apex, in the manner of other Mexican pines The cones are between 4 and 5 inches long [10-12.5 cm], by 1 1/2 in. [3.8 cm] in diameter at the middle, pointed and curved."
Farjon and Styles (1997) designated a lectotype at P consisting of a sheet with foliage, collected by Hartweg at Angangueo, with an isolectotype at MO consisting of a cone scale with seeds.
P. pseudostrobus is morphologically distinguished from its sister taxa by its relatively thin, pliable cone scales having flat apophyses and a small, easily deciduous prickle. It often becomes a large, prominent tree in closed-canopy forest, which is also true of P. montezumae and P. oaxacana, two other pines of subsection Ponderosae that often grow with P. pseudostrobus. At 12–15 mm long, the fascicle sheath is shorter than in the other taxa, and the flexible, drooping foliage is distinct from P. apulcensis subsp. estevezii but not from the other taxa. The seed cones are generally less than 10 cm long, smaller than the other taxa, however large cones sometimes occur. Martínez (1945) did not mention the existence of anomalously large cones, but they were described as forma megacarpa by Loock (1950), a forma accepted by Perry (1991) but synonymized with P. pseudostrobus by Farjon and Styles (1997), albeit without discussion. It seems to be quite rare, with no occurrences inventoried by GBIF (2025年10月27日). The apophysis and umbo of P. pseudostrobus are commonly flat, more so than in any of the other taxa, although in forma protuberans Martínez the umbo becomes a rounded, raised knob 2–3 mm high. With segregation of the taxa in the Oaxacana clade, P. pseudostrobus becomes a much less polymorphic species, and both formae become proportionately more conspicuous and divergent relative to plants of nominal P. pseudostrobus; this supports recognizing both formae as discrete taxa.
Neither distribution nor habitat are particularly distinctive, except that P. pseudostrobus is uncommon south of the Trans-Mexican Volcanic Belt and has not been reported from Guatemala, Honduras or El Salvador. The oleoresin profile is highly distinct from all other taxa, containing no heptane, octane or nonane and comprised of 80% α-pinene, except, that in f. megacarpa α-pinene is reduced to 53% and Δ-3 carene and myrcene rise to 40%; and in f. protuberans the α-pinene is reduced to 47% and Δ-3 carene rises to 45% (Perry 1987 p. 454, Perry 1991 p. 143). The oleoresin data support recognizing f. megacarpa as a distinct taxon. Both Mirov (1958) and Perry (1987, 1991) cite oleoresin composition as a primary reason for segregating P. pseudostrobus s.s. from the taxa here treated in the Oaxacana clade.
Pinus pseudostrobus Lindl. is a valid species in the Pseudostrobus clade, appropriately circumscribed as described by Perry (1991), and by Farjon and Styles (1997) and Farjon (2010) as P. pseudostrobus var. pseudostrobus. The taxon so constituted does not include P. apulcensis, P. apulcensis var. coatepecensis, P. apulcensis subsp. estevezii, or P. oaxacana, all of which are in the Oaxacana clade. Segregation of these taxa makes it a much less polymorphic species, making the formae megacarpa and protuberans more conspicuously divergent. This supports recognizing both as valid taxa at the rank of forma.
Fig. 1899. P. apulcensis (Loudon 1842).
Fig. 1900. P. apulcensis (Loudon 1842).
Fig. 161. Corte transversal de una hoja de Pinus pseudostrobus apulcensis. (Dib. Ing. Manuel Ornelas C.) (Martínez 1945).
Fig. 162. Cono de P. pseudostrobus apulcensis, de Apulco, Hgo. (Fot. del A.) (Martínez 1945).
Illustration of the lectotype of P. apulcensis designated by Farjon (1995).
This taxon was described by Lindley (1839) but reduced to a variety by Shaw (1909) and maintained as such by many subsequent authors (Stead 1983a, 1983b; Stead and Styles 1984; Farjon and Styles 1997; Farjon 2010). As will be shown below, this was an error, compounded with a number of subsequent errors
In 1838 C. T. Hartweg collected a pine in a ravine near Apulco, Hidalgo. This pine was later described by Lindley (1839) as a new species, Pinus apulcensis. Lindley's description of this species was brief, and is here quoted in full: "Pinus apulcensis; pentaphylla, foliis tenuibus abbreviatis ramisque glaucis, strobilis pendulis verticillatis ovatis acutis: squamis rhomboideis pyramidatis rectis nunc elongatis medio constrictis, seminibus ovalibus ala lineari quadruplo brevioribus". Or, in English, "Five-leaved, with thin, shortened, pendulous leaves and glaucous twigs; whorled, ovate, acute cones; elongated, rhomboid, pyramidal, straight scales constricted in the middle; and oval seeds with linear wings four times longer." He added (in English) "The short leaves and very glaucous shoots distinguish this, independently of the ovate cones, covered closely with pyramidal elevations, which are sometimes prolonged and contracted in the middle, especially those near the points of the cones. The leaves are not more than six inches [15 cm] long, the cones are about four inches [10 cm] long, and very regularly ovate. Mr. Hartweg found it in ravines near Apulco growing fifty feet [15 m] high."
It's worth noting that Lindley simultaneously described 5 other species of pines from Hartweg's collections, and so his descriptions are in some measure a comparison of these species. Two of those other species were Pinus hartwegii and P. pseudostrobus, thus close relatives of P. apulcensis and P. oaxacana. Unfortunately Hartweg's specimens were later lost. The best description we have of Hartweg's type specimen is an illustration and text from Loudon (1842). The illustrations are shown at right; Loudon's description adds slightly to Lindley's, and follows:
"The short leaves and very glaucous shoots, the ovate cones, covered closely with pyramidal elevations, which are sometimes prolonged and contracted in the middle, especially those near the points of the cones, readily distinguish this from all other species. The leaves are 6 in. [15 cm] long. The cones are about 4 in. [10 cm] long, being rather larger than a hen's egg; the backs of the scales are sometimes prolonged into a hook, particularly those nearest the base and the point.
"Spec. Char., &c. Leaves in fives, slender, short. Branches glaucous. Cones pendulous, verticillate, ovate, acute. Scales rhomboidal, pyramidal, straight, sometimes prolonged and contracted in the middle. Seeds oval, four times shorter than the linear wing. (Lindl.) A tree. Mexico, near Apulco, in ravines. Height 50 ft. [15 m] Introduced in 1839, by cones sent home by Hartweg, from which many plants have been raised."
Farjon (1995) later designated a lectotype which he interpreted to be material collected by Hartweg and identified by Lindley; however it consists only of a cone and some seeds, and Debreczy and Rácz (2011), based on examination of the lectotype, dispute its validity and interpret it as a specimen of Pinus oaxacana Mirov.
"Lindley, en 1839 estableció la especie Pinus apulcensis (Bot. Reg. XXV. Mise. 6:3) tomando como tipo los ejemplos colectados por Hartweg en Apulco (Hgo.) Setenta años más tarde, G. R. Shaw refundió esta especie como simple variedad del Pinus pseudostrobus y la consideró sinónima de la que existe en Oaxaca, llamándola Pinus pseudostrobus var. apulcensis.
"A mi juicio, estuvo acertado al considerar al Pinus apulcensis como variedad del Pinus pseudostrobus, pero no lo estuvo al declararlo sinónimo de la variedad de Oaxaca. Los ejemplares de Apulco y los de toda la zona vecina carecen de las prolongaciones tan características que se ven en las apófisis de los ejemplares de más al Sur, es decir, Veracruz y Oaxaca. Por otra parte Lindley, en la descripción original de su Pinus apulcensis no menciona tales prolongaciones, sino solamente un pico encorvado que efectivamente se observa.
"Por lo tanto, en el presente arreglo sistemático el Pinus apulcensis de Lindley queda como variedad del Pinus pseudostrobus, en tanto que la variedad Pinus pseudostrobus var. apulcensis de Shaw queda como variedad oaxacana del propio P. pseudostrobus.
"La descripción del Pinus pseudostrobus var. apulcensis es como sigue:
"Arbol de 15 a 20 metros, a veces hasta 30, con la corteza moreno rojiza y agrietada. Ramillas con marcado tinte azuloso. Brácteas salientes y ásperas, algo espaciadas.
"Hojas en grupos de cinco, excepcionalmente seis en algunos fascículos (ejemplares de las faldas de La Malinche Tlax.) de 17 a 27 cm. de largo, rara vez más; triangulares; ásperas, agudas, colgantes y flexibles, medianamente gruesas, de color verde amarillento, finamente aserradas. Canales resiníferos medios, en número de tres o cuatro, más frecuentemente tres. Haces fibrovasculares dos, casi contiguos, pero distintos; paredes externas de las células endodérmicas engrosadas; hipodermo algo grueso en la cara dorsal, con ligeras ondulaciones irregulares hacia el clorénquima.
"Vainas, persistentes, anilladas, de color castaño, de 15 a 25 mm.
"Conillos subcilíndricos, morenos, con tinte cenciento.
"Conos anchamente ovoides u oblongos cónicos, de 10 a 15 cm., por pares, a veces en grupos de 3 ó 4 y pocas veces solitarios; asimétricos, algo oblicuos y levemente encorvados; resinosos, de color café rojizo o algo amarillento, opacos, no pronto caedizos, en apariencia casi sésiles, porque el pedúnculo (de unos 10 a 15 mm.) queda oculto entre las escamas basales y solamente es visible en los conos poco desarrollados.
"Escamas numerosas y robustas, de 3 a 4 cm. de largo, por 1.8 a 2.5 de ancho, con el ápice ancho y fuerte, irregularmente redondeado, o ligeramente anguloso; umbo vagamente cuadrangular, a veces triangular, con quilla levantada y fuerte. Apófisis diédrica, reflejada, con grietas obscuras y convergentes; cúspide cenicienta, algo saliente, invariablemente encorvada hacia la base y rematando en una espinita aguda y no pronto caediza, de 1.5 milímetros.
"Semilla moreno obscura vagamente triangular, de unos 6 a 8 milímetros, con ala de unos 30 mm. de largo por unos 12 de ancho, de color café, con bandas obscuras (Martínez 1945, var. apulcensis)."
"In 1839, Lindley established the species Pinus apulcensis (Bot. Reg. XXV. Mise. 6:3) using as a type the examples collected by Hartweg in Apulco (Hidalgo). Seventy years later, G. R. Shaw recast this species as a simple variety of Pinus pseudostrobus and considered it synonymous with the one found in Oaxaca, calling it Pinus pseudostrobus var. apulcensis.
"In my opinion, he was correct in considering Pinus apulcensis a variety of Pinus pseudostrobus, but he was incorrect in declaring it a synonym of the Oaxaca variety. The specimens from Apulco and those from the entire neighboring area lack the characteristic extensions seen on the apophyses of specimens from further south, that is, Veracruz and Oaxaca. On the other hand, Lindley, in the original description of his Pinus apulcensis, does not mention such extensions, but only a curved beak, which is indeed observed.
"Therefore, in the present systematic arrangement, Lindley's Pinus apulcensis is considered a variety of Pinus pseudostrobus, while Shaw's Pinus pseudostrobus var. apulcensis is considered a Oaxacan variety of P. pseudostrobus itself.
"The description of Pinus pseudostrobus var. apulcensis is as follows:
"Tree 15–20 m tall, sometimes up to 30 m, with reddish-brown, cracked bark. Branchlets with a marked bluish tinge. Bracts are protruding and rough, somewhat widely spaced.
"Leaves in groups of 5, rarely 6 in some fascicles (specimens from the slopes of La Malinche, Tlaxcala), 17–27 cm long, rarely more; triangular; rough, sharp, pendulous, and flexible, medium-thick, yellowish-green, and finely serrated. The median resin canals are 3 or 4 in number, more frequently 3. Two fibrovascular bundles, almost contiguous but distinct; the outer walls of the endodermal cells are thickened; the hypoderm is somewhat thick on the dorsal surface, with slight irregular undulations toward the chlorenchyma. Sheaths are persistent, ringed, brown, and 15–25 mm long.
"Young seed cones are subcylindrical, brown, with a grayish tinge.
"Cones are broadly ovoid or oblong-conical, 10–15 cm long, in pairs, sometimes in groups of 3 or 4, and rarely solitary; asymmetrical, somewhat oblique, and slightly curved; resinous, reddish brown or somewhat yellowish in colour, opaque, not readily deciduous, almost sessile in appearance, because the peduncle (about 10–15 mm) is hidden between the basal scales and is only visible in the poorly developed cones.
"The scales are numerous and robust, 3–4 cm long and 1.8–2.5 cm wide, with a broad, strong, irregularly rounded or slightly angular apex; the umbo is vaguely quadrangular, sometimes triangular, with a raised, strong keel. The apophysis is dihedral, reflexed, with dark, converging cracks; the cusp is ashen, somewhat projecting, invariably curved toward the base and ending in a sharp, not readily deciduous spine, 1.5 mm long.
"The dark brown, vaguely triangular seed is about 6–8 mm long, with a wing about 30 mm long and about 12 mm wide, brown, with dark bands."
Loock (1950) noted Lindley's description and Shaw's failure to describe any specimens from Apulco, thus a pro parte definition of the taxon; Loock discusses the differences between Apulco and Oaxaca specimens and explains that this was the basis for Martínez's separation of var. apulcensis from var. oaxacana. For var. apulcensis he provides a detailed description, illustration, and discusses the habitat at Apulco.
Stead (1983) describes a principal components and canonical discrimination analysis performed upon essentially all taxa in the P. pseudostrobus complex. Unfortunately he fails to present any results of that analysis, stating only his conclusions. One is that examining the internal anatomy of the foliage is essential for reliable identification. Another is that "One sub-group, comprised of most of the specimens representing P. pseudostrobus var. apulcensis, P. pseudostrobus var. estevezii and P. pseudostrobus var. coatepecensis, was partially separated out and proved to have a separate identity when tested using CDA [canonical discriminant analysis]. This group is well defined geographically and ecologically. It is restricted to north-eastern Mexico where it grows on drier sites with sparse associated vegetation. It has been given the rank of subspecies and should be called P. pseudostrobus subsp. apulcensis (Lindl.) Stead" (Stead 1983, p. 28). Given phylogenomic analysis placing these three taxa in the Oaxacana clade (Gernandt et al. 2025), it then becomes parsimonious to recognize P. apulcensis at species rank; Stead's analysis reduces the latter two taxa to synonymy.
Perry (1991) placed the taxa of the P. pseudostrobus complex into Section Pseudostrobus, which he subdivided into subsections Pseudostrobus and Oaxacana based on morphological and oleoresin characters. He placed P. apulcensis into subsection Oaxacana but confusingly used the invalid name Pinus pseudostrobus var. apulcensis Martínez while also saying (p. 150) "I believe ssp. apulcensis should be restored to the rank of species as originally proposed by Lindley (1839)," citing oleoresin data in support of this concept; unfortunately he does not present those data, saying they are in a paper under preparation. He never published such a paper.
Farjon (1995) maintained that Shaw's interpretation of the Apulco pine as P. pseudostrobus var. apulcensis was valid because Shaw cited both Lindley (1839) and Loudon (1842), despite providing illustrations of cones from locations far south of Apulco, two of which illustrations bear very little resemblance to Loudon's illustrations of a supposed type specimen (none of the authorities cited here have disputed the idea that Loudon's illustrations are an acceptable proxy for a type specimen). Farjon asserts that simply because Martínez visited Apulco and collected specimens essentially identical to Loudon's illustration, does not indicate that Martínez in fact located Hartweg's Apulco pine, and that the Apulco pine may not even occur there anymore. This is a specious argument given that both Martinez (1945) and Loock (1950) visited the Apulco sites and found pines there that conformed to Lindley's description and Loudon's illustrations. Farjon also cites the evidence from Stead (1983) indicating that morphological metrics for the Apulco pine cluster with metrics for Martínez's P. pseudostrobus var. estevezii and P. pseudostrobus var. coatepecensis, but this point acquires a very different significance now that phylogenomic evidence has placed all three taxa in the Oaxacana clade. Farjon located a seed cone at W (Vienna) and labeled "P. apulcensis, Lindl." (photo at right) which he asserts is labeled in Lindley's handwriting and which he has designated as the lectotype of P. pseudostrobus var. apulcensis (Lindl.) Shaw.
Farjon and Styles (1997) and Farjon (2010) also maintain this variety, but do not provide new information.
Lindley (1839) described P. apulcensis based on Hartweg's collection at Apulco, Hidalgo. Shaw (1909) described P. pseudostrobus var. apulcensis but neither his description nor illustrations were based on observation of Hartweg's pine; 2 of the 3 cones illustrated were samples of P. oaxacana collected by Nelson in Oaxaca, and his description of the variety seems to have been based on these two cones plus another one collected in México by Pringle, having slightly less prominent apophyses. There is no evidence that Shaw had direct experience of Lindley's pine, and both Mirov (1958) and Debreczy and Rácz (2011) argue that the evidence given by Shaw indicates that he was describing specimens of P. oaxacana rather than of P. apulcensis; certainly Shaw offers no evidence that he observed the Apulco pines directly or through specimens collected by others. Martínez used the name P. pseudostrobus var. apulcensis to describe a pine he found in Apulco, Hidalgo, which was consistent with Lindleys's description. He named this P. pseudostrobus apulcensis (no Shaw) Martínez. This was an invalid name, because he did not specify a rank (variety) or provide a Latin description. Loock (1950) confirmed Martínez's argument that Shaw gave at best a pro parte description, as well as providing new information in the form of a detailed description of the species and its habitat at Apulco. Stead (1983) described conclusions from a multivariate morphological analysis that grouped Martínez's P. pseudostrobus var. apulcensis, P. pseudostrobus var. coatepecensis, and P. pseudostrobus var. estevezii together, separate from P. pseudostrobus. Farjon (1995) cites similar evidence, but Gernandt et al. (2025) turn both Stead's and Farjon's conclusions on their head by showing those three taxa to all be in the Oaxacana clade. Lindley's name, validly published, becomes the first name assigned to a member of the Oaxacana clade. It remains to be determined whether the two other taxa (coatepecensis and estevezii) should be reduced to synonymy or treated as discrete taxa.
Fig . 157. Pinus pseudostrobus coatepecensis. (Dib. Inq. Manuel Ornelas C.) (Martínez 1945).
Fig . 156. Corte transversal de una hoja de P. pseudostrobus coatepecensis. (Dib. Inq. Manuel Ornelas C.) (Martínez 1945).
Pinus apulcensis var. coatepecensis has never been a widely recognized taxon. It was described by Martínez (1945) and maintained as such by Loock (1950), as a variety of P. pseudostrobus. Stead (1983) reduced it to synonymy with P. pseudostrobus var. apulcensis, but Perry (1991) maintained it as a variety. Authorities since Farjon and Styles (1997) have followed Stead in reducing it to synonymy within P. pseudostrobus. It is currently (2025) so treated by POWO.
"Este pino se observó en la región vecina a Coatepec, Ver. Por su aspecto y estructura foliar coincide con el P. pseudostrobus, pero difiere notablemente en la forma y el tamaño del cono.
"Ramulis fuscis cinerascentibus, bracteis sat sparsis, inconspicuis; foliis 5, 20-30 cm. longis triangularibus, flexibilibus, obscure viridibus; ductus resiniferis 2-3, intermedialibus, nonnunquam 1-2 subepidermalibus; endodermate incrassato; fascibus fibrovascularibus 2; hypodermide levi; strobilis late ovoideis, 5.5-8.5 cm. longis fuscis, deflexis, solitariis vel bini, persistentibus, obliquis, pedunculis 10-12 mm. longis; squamis 22 mm. longis, 10 mm. latis, apophysi prominenti, carina transversa fere invisibili, mucrone persistente. Typus in Herb. Instituto de Biología, México.
"Las ramillas son morenas y algo cenicientas, con las brácteas espaciadas y casi hundidas. Sus hojas son 5, de 20 a 23 cm. de largo, triangulares y flexibles, de color verde obscuro. Tienen 2 o 3 canales resiníferos medios, a veces con uno o dos externos; las paredes externas de las células endodérmicas son engrosadas; los haces fibrovasculares son bien distintos y el hipodermo delgado y casi uniforme.
"Vaina de 15 mm. Yemas cilíndricas cónicas, delgadas.
"Conos ovoides o largamente ovoides, de 5.5 a 8.5 cm., moreno obscuros, reflejados, solitarios o por pares, persistentes, ligeramente asimétricos y oblicuos, en pedúnculos de 10 a 12 mm.
"Escamas duras, más desarrolladas en el lado externo del cono, de 22 mm. de largo por 10 de ancho; apófisis prominentes en la cara externa y poco levantadas en la cara interna, con la costilla perpendicular casi invisible, diédricas, con espina persistente.
"Se colectó en terrenos del Ingenio del Rosario, cerca de Xico, Ver."
Martínez's illustrations of var. coatepecensis are shown at right.
"This pine was observed in the region near Coatepec, Ver. In appearance and leaf structure it coincides with P. pseudostrobus, but differs notably in the shape and size of the cone.
"Branchlets dark gray, bracts quite sparse, inconspicuous; leaves 5, 20-30 cm. long, triangular, flexible, obscurely green; resin ducts 2-3, medial, sometimes 1-2 external; thickened endoderm; fibrovascular bundles 2; hypodermis light; seed cone broadly ovoid, 5.5-8.5 cm. long, dark, deflexed, solitary or paired, persistent, oblique, peduncles 10-12 mm. long; scales 22 mm. long, 10 mm. wide, prominent apophysis, almost invisible transverse ridge on apophysis, persistent prickle. Type in Herb. Instituto de Biología, México.
"The twigs are brown and somewhat ashen, with widely spaced, almost sunken bracts. The leaves are in fascicles of five, 20 to 23 cm long, triangular, flexible, and dark green. They have two or three medial resin canals, sometimes with one or two external ones; the outer walls of the endodermal cells are thickened; the fibrovascular bundles are distinct, and the hypoderm is thin and almost uniform.
"Sheath 15 mm long. Buds are cylindrical, conical, and thin.
"Cones are ovoid or long-ovoid, 5.5 to 8.5 cm, dark brown, reflexed, solitary or in pairs, persistent, slightly asymmetrical and oblique, on 10 to 12 mm peduncles.
"Hard scales, more developed on the outer side of the cone, 22 mm long by 10 mm wide; apophyses are prominent on the outer surface and slightly raised on the inner surface, with the perpendicular rib almost invisible, dihedral, with a persistent spine.
"Collected on land at the Ingenio del Rosario, near Xico, Veracruz."
Loock (1950) determined that var. coatepecensis "generally agrees with the type [P. pseudostrobus], except that the cones are quite different in form, texture and size." He provides a somewhat more detailed description than Martínez but gives little other information. Stead (1983), discussed above (P. apulcensis), describes conclusions from a multivariate morphological analysis that groups Martínez's P. pseudostrobus var. apulcensis, P. pseudostrobus var. estevezii and P. pseudostrobus var. coatepecensis together, separate from P. pseudostrobus. He uses this result to justify assigning the latter two taxa to synonymy under his P. pseudostrobus var. apulcensis. This has been the majority opinion down to the present. However, Perry (1991, p. 154) reports that the oleoresin composition of var. coatepecensis is "quite different from that of P. pseudostrobus and very similar to turpentine of P. oaxacana." Unfortunately he provides no quantitative information on the oleoresin content. When Perry (1991) discusses the oleoresin content of P. pseudostrobus and its two formae, he also shows that they are quite different from the type forma, so Perry's use of the words "quite different" does not justify infraspecific rank as variety or subspecies. Escobar-Alonso et al. (2023), in a multivariate morphological analysis of the P. pseudostrobus s.l. taxa, find that coatepecensis is morphologically distinct, but the differences are subtle. No phylogenomic work has been done using specimens of var. coatepecensis.
The morphological analysis by Stead (1983) and the oleoresin evidence reported by Perry (1991) both indicate that var. coatepecensis is within the Oaxacana clade, although no phylogenomic analysis has yet verified this as the published analyses have not included a specimen of var. coatepecensis. Indeed, there are very few described specimens; GBIF (2025年10月27日) inventories only 23 specimens. Martínez (1945) only cites its occurrence in Veracruz; Loock (1950) adds Oaxaca; and Perry (1991) adds Chiapas and Guatemala. Based on this evidence the taxon is apparently very similar in morphology to P. apulcensis and is represented by occasional morphologically distinct specimens that show no consistent ecological or biogeographical pattern. Var. coatepecensis cannot be shown to be a distinct taxon and is conservatively treated as synonymous with P. apulcensis.
Perry 1982 figure showing tree
Pinus apulcensis subsp. estevezii, showing a tree in habitat (Perry 1982).
Perry 1982 figure showing twigs cones and foliage
Pinus apulcensis subsp. estevezii, showing twigs, cones, and foliage (Perry 1982).
Perry 1982 table with oleoresin data
Perry's (1982) Table 2 comparing oleoresin data for P. estevezii, P. pseudostrobus, and P. montezumae.
Portion of the phylogenomic tree presented in Figure 1 of Gernandt et al. (2025) depicting the taxa commonly regarded as closely related to Pinus pseudostrobus.
Pinus pseudostrobus var. estevezii Martínez, raised to species rank by Perry (1982), is a tree of the dry northeastern states with stiff, erect leaves and relatively large, smooth cones bearing a persistent prickle. As noted above, phylogenomic analysis places this taxon in a clade with a sample of var. apulcensis collected at Apulco (Gernandt et al. 2025), as a member of the Oaxacana clade. Although currently treated by POWO as a synonym of P. pseudostrobus, the phylogenomic evidence, coupled with the species' distinctive morphology and distinctive semiarid habitat, warrant its treatment at subspecies rank: P. apulcensis subsp. estevezii (Martínez) Earle sp. nov.
"Este pino, por su aspecto general se asemeja al P. pseudostrobus y al P. Montezumae, pero presenta algunas características sobre todo en el cono, que ameritan a mi juicio que se le considere como variedad del primero.
"Foliis 5, raro 4, 20–36 cm. longis, plerumque 20–30, triangularibus, laete viridibus, nitidis, sat rigidis, scabris marginibus minute serrulatis; hypodermate incrassato, irregulariter in parenchyma penetrabili; doctibus resiniferis 3–5 intermediis, nonnunquam I interno; fascibus fibrovascularibus 2, distinctis, endodermatis facie externa incrassata; strobilis longe ovoideis, acuminatis, deflexis, obliquis, 10–13 cm. longis, pallide brunneis, subnitentibus, binis, ternis vel quaternis; pedunculis circiter 10 mm. longis; squamis 30 mm. longis, 15 mm. latis; apophysi subpyramidata, cuspidata, cinerascente, mucrone 1–1.5 mm. longe Habitat in Cañón de las Mieleras, Santa Catarina, Nuevo León, Typus in Herb. Instituto de Biología, México.
"Sus ramillas son morenas; de superficie áspera, con las bases de las brácteas muy salientes y iuntas, pero menos fuertes y bulladas que en el P. Montezumae.
"Hojas en grupos de 5, excepcionalmente 4 en algunos fascículos de 20 a 36 cm. de largo, pero más comúnmente de 20 a 30, triangulares, de color verde claro, brillantes, algo tiesas y ásperas, con los bordes finamente aserrados. El hipodermo es grueso e irregular, con numerosas entrantes en el clórenquima, generalmente muy profundas; los canales resiníferos son de 3 a 5, medios, a veces con uno interno; las paredes externas de los células del endodermo son levemente engrosadas y los haces fibrovasculares bien definidos y distintos.
"Vainas de 15 a 30 mm. de color castaño cuando jóvenes y cenicientas después.
"Yemas cortas, ovoides y acuminadas, de color amarillento.
"Conillos subterminales, oblongos, de color violáceo rosado, con puntas extendidas.
"Conos largamente ovoides, acuminados, oblicuos, asimétricos y reflejados (por excepción rectos y asimétricos), de 10 a 13 cm., de color café amarillento, levemente lustrosos; colocados por pares o en grupos de 3 ó 4, en pedúnculos de 10 mm. o menos, los cuales, al caer el cono, quedan en la ramilla con algunas escamas basales. Escamas duras y fuertes, más desarroliadas las del lado externo del cono, de unos 30 mm. de largo, por 15 de ancho; de ápice anguloso o redondeado; quilla transversal muy fuerte y levantada y una débil costilla perpendicular en la parte inferior; apófisis subpiramidal, levantada unos 7 mm. en las escamas externas; cúspide cenicienta, con espinita extendida, fuerte y persistente, de 1 a 1.5 mm.
"Semilla morena, cosi oval, de unos 7 mm. con ala de 25 mm. de largo por 9 de ancho.
"Se colectó en el Cañón de las Mieleras, Sierra de Santa Catarina N. L. en los Picachos de Sabinas, N. L. y en Los Lirios, Arteaga, Coah.
"Se diferencia de la especie típica por sus ramillas ásperas, pues las bases de las brácteas son más salientes; por su hipodermo más grueso e irregular, por las células del endodermo, cuyas paredes externas son levemente engrosadas, por su cono largamente ovoide y acuminado, fuerte, oblicuo y asimétrico, con escamas muy duras, con apófisis levantadas, provistas de una espinita persistente. Guarda relación con el P. Montezumae por sus hojas fuertes y por su hipodermo grueso y penetrante.
"Hay uno de cono menor (6 cm.) anchamente ovoide, que parece establecer la relación con la variedad coatepecensis. Todavía se ha observado otro de cono más grande y con escamas más numerosas, procedente de Pahuatlán, Pue. Falta mayor observación para decidir si pueden consignarse como formas bien definidas."
"This pine in its general appearance resembles P. pseudostrobus and P. Montezumae, but presents some characteristics especially in the cone that in my opinion deserve to be considered as a variety of the former.
"Leaves 5, rarely 4, 20–36 cm. long, usually 20–30, triangular, bright green, shiny, quite rigid, scabrous margins minutely serrulate; hypoderm thickened, irregularly penetrable in chlorenchyma; resin ducts 3–5, medial, sometimes 1 internal; fibrovascular bundles 2, distinct, endoderm with thickened external face; seed cones long-ovoid, acuminate, deflexed, oblique, 10–13 cm. long, pale brown, nearly sessile, in groups of two, three or four; peduncles about 10 mm. long; scales 30 mm. long, 15 mm. wide; apophysis subpyramidal, cuspate, cineraceous, cusp 1–1.5 mm. long. Habitat in Cañón de las Mieleras, Santa Catarina, Nuevo León; type in Herb. Instituto de Biología, México.
"Twigs brown; they have a rough surface, with very prominent and closely-spaced bract bases, but less robust and blistered than those of P. montezumae.
"Leaves are in groups of 5, rarely 4 in some fascicles, 20–36 cm long, but more commonly 20–30, triangular, light green, shiny, somewhat stiff and rough, with finely serrate edges. The hypoderm is thick and irregular with numerous, generally very deep chlorenchyma indentations; the resin canals are 3–5, medial, sometimes with an internal one; the outer walls of the endoderm cells are slightly thickened, and the fibrovascular bundles are well-defined and distinct.
"Fascicle sheaths 15–30 mm long, brown when young, later ashen.
"Buds short, ovoid, acuminate, yellowish.
"First-year seed cones subterminal, oblong, pinkish-purple, with extended tips.
"Seed cones long-ovoid, acuminate, oblique, asymmetrical, reflexed (some are straight and asymmetrical), 10–13 cm long, yellowish-brown, slightly glossy; arranged in pairs or in groups of 3 or 4, on peduncles 10 mm or less in size, which, when the cone falls, remain on the branch with some basal scales. Scales are hard and strong, those on the outer side of the cone being more developed, about 30 mm long by 15 mm wide; with an angular or rounded apex; a very strong and raised transverse keel and a weak perpendicular rib on the lower part; a subpyramidal process, raised about 7 mm on the outer scales; and an ash-colored cusp with a strong, persistent, extended spine, 1–1.5 mm long.
"The seed is brown, more or less oval, about 7 mm in diameter, with a wing 25 mm long by 9 mm wide.
"It was collected in the Cañón de las Mieleras, Sierra de Santa Catarina, Nuevo León, in the Picachos de Sabinas, Nuevo León, and in Los Lirios, Arteaga, Coahuila.
"This variety is distinguished from the typical species by its rough twigs with more prominent bract bases; by its thicker and more irregular hypoderm; by the endoderm cells, whose outer walls are slightly thickened; and by its long, ovoid, acuminate, strong, oblique, and asymmetrical cone, with very hard scales, raised apophyses, and a persistent spine. It is related to P. montezumae by its strong leaves and its thick, penetrating hypoderm.
"There is one with a smaller cone (6 cm) and a broadly ovoid shape, which appears to establish a relationship with var. coatepecensis. Another, with a larger cone and more numerous scales, has been observed from Pahuatlán, Pue. Further observation is needed to determine whether these can be classified as well-defined forms."
Loock (1950) generally followed Martínez's description of var. estevezii, but in comparing it to Pinus pseudostrobus noted certain differences: "its cone is long-ovate, acuminate towards the apex, oblique, with apophyses raised and provided with a strong, persistent prickle". The raised apophyses and persistent prickle are the most conspicuous morphological characters of the Oaxacana clade. Loock (1950) also provided greater ecological detail on this species, describing it as "a small, dense-crowned tree ... it grows as scattered trees under rather dry conditions in deep soil on the lower slopes of the mountains at an elevation of about 5,000 to 6,000 feet [1524-1829 m]. It is usually associated with P. greggii and P. rudis [P. hartwegii]." Gaussen (1960) raised var. estevezii to species rank, but his publication of the name is invalid since he did not refer to the original publication. Mirov (1961) followed Martínez and Loock in his treatment of var. estevezii. Perry (1982) raised var. estevezii to species rank based on evidence "from numerous field observations, morphological studies, and chemical analyses of stem oleoresins from Pinus montezumae, P. pseudostrobus, and P. pseudostrobus var. estevezii." (Two of Perry's illustrations are shown at right.) In a morphological comparison with P. montezumae and P. pseudostrobus, he found that estevezii has hard, thick cone scales like P. montezumae (and like other members of the Oaxacana clade). It also has a strong, persistent prickle (like other members of the Oaxacana clade), unlike both P. montezumae and P. pseudostrobus. He noted that the foliage is stiff and erect, unlike all other taxa discussed here. The hypoderm is irregular with many penetrations into the chlorenchyma, like other members of the Oaxacana clade and unlike both Pinus montezumae and P. pseudostrobus. Also it is a relatively small tree, not more than 20 m tall, unlike all other taxa discussed here except P. apulcensis; and its habitat at 800–1800 m is a lower mean elevation than all other taxa discussed here. There are many other minor morphological distinctions, but the most compelling evidence distinguishing estevezii from P. montezumae and P. pseudostrobus is that from xylem oleoresins, shown at right ("Table 2" from Perry 1982). The complete absence of heptane, octane and nonane from P. montezumae and P. pseudostrobus, while these are the predominant compounds in P. estevezii, is most noteworthy, as is the much lower percentage of α-pinene in P. estevezii compared to the other two taxa.
Perry (1991) recognized Pinus estevezii but did not add to his 1982 analysis. Farjon and Styles (1997) placed P. estevezii into synonymy with P. pseudostrobus while acknowledging but not addressing the morphological and chemical evidence put forward by Perry (1982). Farjon (2010) maintained this position, while Debreczy and Rácz (2011) treat P. estevezii at species rank, adding to Perry's analysis by noting its occurrence with P. arizonica, P. cembroides, P. greggii, and P. nelsonii; they also are less emphatic about the hard, thick cone scales emphasized by Perry (1982), characterizing them as "rigidly stiff". Finally, phylogenomic evidence has recently been developed that considered both nuclear and plastid sequences for 87 samples representing all members of subsection Ponderosae, including two samples of P. estevezii from Nuevo León (Gernandt et al. 2025). Both samples appeared sister to one sample identified as P. pseudostrobus var. apulcensis, collected at the type locality in Apulco, Hidalgo. These two taxa were sister to a clade comprised of all four samples of P. oaxacana, with the combined clade sister to another clade comprised of 18 samples of P. hartwegi, P. montezumae, and P. pseudostrobus (also one sample identified as P. martinezii but collected with and very similar to P. montezumae; it may have been misidentified); the relevant portion of Gernandt et alia's Figure 1 is reproduced at right.
Morphology, oleoresin data and phylogenomic evidence each independently establish that this taxon is in the Oaxacana clade, thus its treatment by Farjon and Styles (1997) as a synonym of P. pseudostrobus makes the latter taxon polyphyletic. The question remains, is it synonymous with any other taxa in the Oaxacana clade? The first possibility is that it is synonymous with or infraspecific to P. apulcensis. The two taxa are sister in the phylogenomic analysis. Morphologically they are close enough that Martínez (1945) treated both as varieties of P. pseudostrobus, and the comparison table shown above indicates that in most characters they are indistinguishable. The primary difference is in foliage aspect (pendulous in P. apulcensis, stiff and erect in P. estevezii). They also have a disjunct distribution, with P. apulcensis more southerly (Hidalgo, México, Puebla, Tlaxcala, Veracruz) while P. estevezii is only in Nuevo León and small areas in the adjacent states of Coahuila and Tamaulipas. P. estevezii habitat is also substantially more xeric than that of P. apulcensis: lower elevation (800–1800 vs. 1800–2200 m), less rainfall (300–400 vs. 1000–1500 mm), and associated with different pines that themselves are more typical of a cool semiarid environment. This evidence suggests that P. apulcensis and P. estevezii are sister taxa distinguished by prominent habitat differences but minor morphological ones, and thus that P. estevezii warrants treatment as a subspecies of P. apulcensis. It is here so described.
Fig. 163. Pinus pseudostrobus oaxacana Perote Ver., (Fot. del A.) (Martínez 1945).
Fig. 164. Corte transversal de una hoja de Pinus pseudostrobus oaxacana. (Dib. Ing. Manuel Ornelas C.) (Martínez 1945).
Fig. 165. Cono del P. pseudostrobus oaxacana. (Dib. Ing. Manuel Ornelas C.) (Martínez 1945).
Fig. 166. Cono del P. pseudostrobus oaxacana. (Fot. del A.) (Martínez 1945).
Fig. 167. P. pseudostrobus oaxacana: pedunculo persistente, conillos, yema y escamas. (Dib. Inq. Manuel Ornelas C.) (Martínez 1945).
Fig. 168. P. pseudostrobus oaxacana, de Teopisca, Chis. (La cuspide es menos saliente que en la forma tipica) (Fot. del A.) (Martínez 1945).
Portion of the phylogenomic tree presented in Figure 1 of Gernandt et al. (2025) depicting the taxa commonly regarded as closely related to Pinus pseudostrobus.
Martínez (1945) described Pinus pseudostrobus var. oaxacana on the basis of two cones collected by Nelson in Oaxaca; Martínez rejects Shaw's identification of these cones as P. apulcensis. Mirov (1958) raised this variety to species rank (P. oaxacana) based on Martínez's analysis of morphology and his own analysis of needle terpene composition. This decision has been supported by phylogenomics; Gernandt et al. (2025) found that 4 of their 5 specimens identified as P. pseudostrobus var. apulcensis and collected in southern states (Puebla, Oaxaca, Chiapas) and Guatemala shared a clade with each other (a fifth, as noted above, was collected at Apulco and fell into a clade with the P. estevezii specimens). Thus it is the nominal species in the Oaxacana clade.
"Arbol de 20 a 40 metros, corpulento, de corteza gruesa y agrietada, moreno obscura, exteriormente grisácea. Ramas fuertes y extendidas; ramillas verticiladas, moreno rojizo o café amarillentas, con tinte glauco, casi lisas o muy poco ásperas, con marcado tinte azuloso en sus partes más tiernas. Bases de las brácteas con el ápice oval, algo espaciadas y salientes, a veces tanto como en el P. Montezumae, sobre todo en ejemplares de la región de Tehuacán, Pue.
"Hojas en grupos de 5 (muy rara vez 6 en algunos fascículos), de 20 a 35 cm. de largo, de color verde claro, con tinte amarillento; delgadas, flexibles y colgantes; triangulares y agudas, finamente aserradas, con los dientecillos delgados y aproximados. Tienen esto mas en las tres caras, unas cinco hileras en la cara dorsal y 3 ó 4 en cada una de las laterales. Los canales resiníferos son medios, en número de 3 a 4, rara vez dos (en algunos ejemplares de Perote Ver.) los haces fibrovasculares son dos, muy aproximados o casi contiguos, en ocasiones poco distintos; el hipodermo es delgado, casi parejo o con entrantes apenas marcadas en el clórenquima; las paredes exteriores de las células endodérmicas son muy engrosadas.
"Las vainas nuevas miden unos 30 mm. y son escamosas, de color castaño, pero se acortan después hasta casi la mitad, se hacen anilladas arriba y toman coloración grisácea.
"Las yemas son cortas, cilíndrico cónicas, y de color castaño.
"Los conillos son subterminales y subglobulosos, a tenuados en ambas extremidades, de color azuloso, algo rojizo, con escamas gruesas y aquilladas, provistas de espinas dirigidas hacia el ápice.
"Conos semipersistentes, colocados por pares o en grupos de 3 y en ocasiones de 4, de 10 a 16 cm. de largo, anchamente cónicos o cónico oblongos, ligeramente encorvados y oblicuos, asimétricos con frecuencia resinosos; de color moreno rojizo o café amarillento; se encuentran generalmente en los nudos y son subsésiles o con el pedúnculo corto, de 5 a 10 mm. y casi oculto entre las escamas basales, algunas de las cuales quedan con él cuando cae.
"Escamas fuertes, irregularmente desarrolladas, de ápice redondeado o irregularmente obtuso; de 3 a 4 cm. de largo, por 1.2 a 2.5 cm. de ancho en el ápice, ensanchadas en la parte media, aplanadas por dentro, con apófisis duras y salientes, hinchadas, desiguales, vagamente subcónicas o subpiramidales, extendidas o algo reflejadas, provistas de una prolongación cenicienta, ancha y generalmente aplanada, de dimensiones variables, corta y gruesa en algunas escamas y larga hasta de 25 mm. en otras, extendida o dirigida hacia la base del cono, aunque en ocasiones, principalmente en las escamas superiores, se dirige hacia el ápice; termina en una punta corta y caediza. La semilla es vagamente triangular, obscura, de unos 7 a 9 mm. con ala de 20 a 35 mm. de largo, por unos 3 de ancho.
"La madera es blanca, ligeramente amarillenta.
"La prolongación de las apófisis que caracteriza a esta variedad es más patente en los ejemplares que proceden de Oaxaca y en algunos de Perote, Ver., pues los de Pahuatlán, Pue., San Rafael Méx. y Las Casas, Chis. presentan escamas más angostas y uniformes, con las prolongaciones cortas (de 5 a 6 mm.) o casi si ellas. En muchos ejemplares de Las Margaritas, Comitán y Las Casas, Chis, se observaron las apófisis subcónicas y con las prolongaciones a penas notables. Los de Pahuatlán y algunos de Perote parecen establecer la transición entre la Variedad apulcensis y la oaxacana" (Martínez 1945, var. oaxacana)."
"A stocky tree, 20–40 m tall, with thick, cracked, dark brown bark and a grayish exterior. The branches are strong and spreading; the branchlets are whorled, reddish brown or yellowish brown, with a glaucous tinge, almost smooth or very slightly rough, with a marked bluish tinge on their tender parts. The bract bases are oval-tipped, somewhat widely spaced and prominent, sometimes as prominent as in P. Montezumae, especially in specimens from the Tehuacán region of Pue.
"Leaves in groups of 5 (very rarely 6 in some fascicles), 20 to 35 cm long, light green with a yellowish tinge; thin, flexible and hanging; triangular and acute, finely serrated, with thin, approximate teeth. They have these more on all three sides, about five rows on the dorsal side and 3 or 4 on each of the lateral sides. The resin canals are medial, numbering 3 to 4, rarely two (in some specimens from Perote Ver.) The fibrovascular bundles are two, very approximate or almost contiguous, sometimes barely distinct; the hypoderm is thin, almost even or with barely marked indentations in the chlorenchyma; the outer walls of the endodermal cells are very thickened.
"The young pods [pollen cones?] measure about 30 mm and are scaly and brown, but later shorten to almost half their length, become ringed at the top, and take on a grayish color.
"The buds are short, cylindrical-conical, and brown.
"Young seed cones are subterminal and subglobular, to attenuate at both ends, bluish, somewhat reddish, with thick, keeled scales and spines directed toward the apex.
"The cones are semi-persistent, arranged in pairs or in groups of three and sometimes four, 10–16 cm long, broadly conical or oblong-conical, slightly curved and oblique, asymmetrical, often resinous; reddish brown or yellowish brown. They are generally found at the nodes and are subsessile or with a short peduncle, 5–10 mm, and almost hidden among the basal scales, some of which remain with it when it falls.
"The scales are strong, irregularly developed, with a rounded or irregularly obtuse apex; 3–4 cm long and 1.2–2.5 cm wide at the apex, widened in the middle, flattened internally, with hard, projecting apophyses, swollen, unequal, vaguely subconical or subpyramidal, extended or somewhat reflexed, provided with a broad, ashy, generally flattened, variable-sized extension. This extension is short and thick in some scales and up to 25 mm long in others. It extends or points toward the base of the cone, although occasionally, especially in the upper scales, it points toward the apex. It ends in a short, drooping point. The seed is vaguely triangular, dark, about 7 to 9 mm long, with a wing 20–35 mm long and about 3 mm wide.
"The wood is white, slightly yellowish.
"The elongated apophyses that characterize this variety are more evident in specimens from Oaxaca and some from Perote, Veracruz, since those from Pahuatlán, Pue., San Rafael, Mexico, and Las Casas, Chis., have narrower and more uniform scales, with short extensions (5–6 mm) or almost none at all. In many specimens from Las Margaritas, Comitán, and Las Casas, Chis., subconical apophyses were observed with barely noticeable extensions. Those from Pahuatlán and some from Perote seem to establish the transition between the Apulcensis variety and the Oaxacan variety."
Martínez's description of var. oaxacana is invalid because he did not provide a Latin description of the taxon; thus the first valid description using the epithet oaxacana is that of Mirov (1958).
Tree 20–30 m. tall, the spring shoots uninodal, glaucous; leaves 5 in a fascicle, 20–33 cm. long, serrulate, very slender, flexible, drooping; dorsal stomata mostly 5–7 rows and ventral stomata 3–5 rows on each side; hypodermis of 2–4 layers of cells, uniform or multiform; resin ducts medial, 2–4; endodermis with outer cell walls thick; vascular bundles 2, close together; sheaths about 28–18 mm. long, persistent; cones subterminal, 1–3, subsessile, 10–14 cm. long, ovoid or conic, acute, slightly asymmetrical or oblique, opening at maturity, deciduous above lowest scales; scales with apophyses ca. 12–20 mm. broad and 8–12 mm. high, rhomboidal, thick, keeled, the apophyses with projections prominent, elongate, unequal (those on abaxial side of cone longer), 5–22 mm. long, 5–12 mm. wide at base, 3–8 mm. thick at base, pyramidal to conic, hard, flattened, straight or curved and reflexed, the umbo on outer part of each projection ending in a short point; seeds 6–7 mm. long, obovoid, dark brown, with detachable brown wing ca. 20 mm. long and 8–9 mm. wide.
The turpentine is composed of n-heptane, 21 percent; d, dl-α-pinene, 51 percent; 1, dl-limonene, 15-16 percent; n-undecane, 1.3 percent; and a sesquiterpene, longifolene, 7.5 percent.
Stead (1983) describes a principal components and canonical discrimination analysis performed upon essentially all taxa in the P. pseudostrobus complex. Unfortunately he fails to present any results of that analysis, stating only his conclusions. One is that P. oaxacana is a distinct taxon, which he treats at varietal rank as P. pseudostrobus var. oaxacana (Mirov) Harrison. His analysis is "Numerous individuals included in the PCA [principal components analysis] had been labelled at collection P. pseudostrobus var. oaxacana. These did not group together in the analysis nor did they show any distinct geographical or ecological identity. Despite the conspicuous nature of the apophysis which characterizes this taxon it is only worthy of varietal rank." However, Perry (1991) reiterates Mirov's point about the strong differences in oleoresin content between P. pseudostrobus and P. oaxacana, citing also his own analysis of those differences presented in Perry (1987; Table 2 shown at right). Certainly those differences are very large; heptane, octane and nonnane account for 41% of P. oaxacana oleoresins but are completely absent from P. pseudostrobus, whereas α-pinene accounts for 37% of P. oaxacana oleoresins but 80% of P. pseudostrobus oleoresins. Farjon and Styles (1997) and Farjon (2010) treat P. oaxacana as a synonym of their P. pseudostrobus var. apulcensis, as discussed earlier, whereas Debreczy and Rácz (2011) continue to hold P. oaxacana as a good species; but none of these authorities introduce substantial new information. However, Gernandt et al. (2025) included 5 samples of P. pseudostrobus var. apulcensis (sensu Farjon 2010) in a phylogenomic analysis that considered both nuclear and plastid sequences for 87 samples representing all members of subsection Ponderosae. Four of the five samples were from southern states and supported P. oaxacana within a clade that also included P. apulcensis and P. apulcensis subsp. estevezii, with the combined clade sister to another clade comprised of 18 samples of P. hartwegi, P. montezumae, and P. pseudostrobus (also one sample identified as P. martinezii but collected with and very similar to P. montezumae); the relevant portion of Gernandt et alia's Figure 1 is reproduced at right.
One infraspecific taxon has been named, Pinus oaxacana var. diversiformis Debreczy & I.Rácz (1995). The variety has attracted no attention, and is not even mentioned by Debreczy and Rácz (2011). It is here treated as a synonym of P. oaxacana.
Morphology and phylogenomic evidence each independently establish that this taxon is in the Oaxacana clade, thus its treatment by Farjon and Styles (1997) as a variety of P. pseudostrobus makes the latter taxon polyphyletic. The question remains, is it infraspecific to the other species in that clade, P. apulcensis? Morphologically P. apulcensis and P. oaxacana are quite similar, which is why Martínez (1945) treated both as varieties of P. pseudostrobus. However, the large apophyses of P. oaxacana present a conspicuous and consistent difference between the taxa, and an equally significant difference appears in needle anatomy, where P. oaxacana lacks the penetration of hypoderm into chlorenchyma that is seen in both subspecies of P. apulcensis. The phylogenomic analysis (Gernandt et al. 2025) places the 4 P. oaxacana samples sister to a clade consisting of P. apulcensis and two samples of P. apulcensis subsp. estevezii (using the names proposed here), thus the combination P. apulcensis subsp. oaxacana is viable, but it is still less similar to P. apulcensis than is subsp. estevezii; this suggests that treatment at species rank is appropriate. P. apulcensis and P. oaxacana also have different ranges and climatic tolerances; P. apulcensis occurs in generally cooler, drier and more northerly sites, associated with pines such as P. montezumae, P. pseudostrobus, P. leiophylla and P. teocote; while P. oaxacana occurs widely to as far south as El Salvador and Honduras, and is associated with pines such as P. gordoniana, P. maximinoi, and P. patula. Accordingly, P. oaxacana is best treated at species rank, sister to P. apulcensis.
Illustration, Fig. 1 from Perry (1987).
A tree in habitat, El Salvador; Fig. 2 from Perry (1987).
Leaf cross-section, Fig. 3 from Perry (1987).
Comparison of oleoresins of four taxa in the Pinus pseudostrobus complex; Table 2 from Perry (1987).
Perry (1987) described P. nubicola from the cloud forests of Chiapas, Guatemala, Honduras and El Salvador. It was reduced to synonymy with typical P. pseudostrobus by Farjon and Styles (1997); however their rationale for this decision admits that it is essentially a conservative decision based on a near-absence of information. Morphologically, the thick, woody cone scales and persistent prickle place it in the Oaxacana clade. As of late 2025, there has been almost no further work, but the terpene composition of P. nubicola resembles that of P. apulcensis subsp. estevezii and P. oaxacana (Perry 1987), while cpDNA haplotypes match those of Sierra Madre Oriental P. pseudostrobus (Gernandt et al. 2009). Gernandt et al. (2009) concluded "We tentatively support the recognition of this species, based on its biochemical and morphological differences from P. pseudostrobus var. pseudostrobus." Unfortunately no specimen was included in the analysis by Gernandt et al. (2025). It is here treated as a synonym of P. oaxacana, an assignment that could well change with further phylogenomic study.
Pinus nubicola was described by Perry (1987), linked below; his Figure 1 is at right. His Table 3 gives a morphological comparison between P. nubicola and the closely-related taxa, P. estevezii, P. oaxacana, and P. pseudostrobus; it is a relatively large tree with needles usually in fascicles of 5 but commonly 6, occasionally 7, and rarely 8. The foliage is more drooping or pendant than that of the other taxa, and the needles are sometimes very long, commonly to 40 and sometimes to 43 cm. The cones are relatively flat-surfaced as in P. estevezii and P. pseudostrobus, in marked contrast to the very pronounced apophyses of P. oaxacana; Perry (1987) also notes that it has "large, ovoid to long-ovoid cones with unusually wide, thick cone scales having unequal apical projections and a small depressed umbo." Apart from this, and as shown in the table assembled above, there are few morphological differences between P. nubicola and the other taxa considered in this review. The oleoresin composition (Perry 1987, Table 2) is strongly different from P. pseudostrobus, which has no heptane, octane, or nonane, and consists mainly (80%) of α-pinene. Limonene is higher than in the other taxa, while Myrcene and β-phellandrene are substantial elements of P. estevezii but nearly absent in both P. nubicola and P. oaxacana. Ecologically, P. nubicola is roughly comparable in elevation, climate, and associated species to P. oaxacana and P. pseudostrobus, but is very different from the relatively xeric P. estevezii, as discussed above. Perry (1987) bases his description on observation and collection of trees from 18 sites in Chiapas, Guatemala, El Salvador, and Honduras, plus one disjunct location in Veracruz. He suggested that natural hybrids occur between P. nubicola and P. montezumae, P. oaxacana, and P. pseudostrobus. He does not provide any explicit rationale for treating this taxon at species rank, except to say "this species differs from P. pseudostrobus, P. oaxacana, and P. estevezii both in turpentine chemistry and in leaf and cone morphology."
Perry (1991) provides no further information except to place P. nubicola within his subsection Oaxacana. Farjon and Styles (1997) class P. nubicola as a synonym of P. pseudostrobus var. pseudostrobus. Their discussion notes that although they could review few herbarium specimens, they did visit at least one of Perry's collection locales and found the trees there to be morphologically quite variable; as with the other taxa discussed here, they feel that the full range of described morphological variation falls within their species concept of P. pseudostrobus var. pseudostrobus. Farjon (2010) maintains P. nubicola as a synonym of P. pseudostrobus var. pseudostrobus. Debreczy and Rácz (2011), though, regard it as a good species, finding it clearly distinct from each of the other taxa discussed here, on both morphological and ecological grounds. No other authors have contributed to the discussion, and as of late 2025, GBIF still records only 18 specimens assigned to P. nubicola: 7 from a single locale in Veracruz, 2 from Chiapas, 6 from Guatemala, and the others from unspecified locales. Only one phylogenomic study has addressed P. nubicola, a study of chloroplast sequences from most taxa in subsection Ponderosae; it found that P. nubicola haplotype composition is most similar to that of P. pseudostrobus from the eastern Sierra Madre Oriental (Gernandt et al. 2009).
P. nubicola is at best a rare taxon. Oleoresin data place it within the Oaxacana clade and within that clade, morphological data seem to place it most closely to P. apulcensis, but this is a tentative conclusion because Perry (1987) did not address that species and herbarium specimens for the two taxa have not been examined; no images are available. I have been in touch with an El Salvador botanist, Fernando Tobar, who has observed plants of nubicola in habitat; in his opinion, it is morphologically most similar to P. oaxacana, to the point where the two taxa are not clearly distinct. No oleoresin data have been published for P. apulcensis, but the limited available data indicate oleoresin similarities between P. nubicola and P. oaxacana; the two also have similar ecological settinngs and similar distributions. The best available genomic data merely confirm that P. nubicola is in the P. pseudostrobus complex. Pending further study, it is most conservatively treated as a synonym of P. oaxacana, to which it bears a close morphological resemblance, while occurring within a similar range and a similar ecological context.
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