Agave pintilla versus victoria-reginae

[AGAVE_KILLER]

Obtained as victoria-reginae from Greg Starr. Increasingly believe it looks more like the plants at the pintilla type locality at Mezquital Durango. The plant is extremely compact and diminutive, it finished the growing season with 50 leaves (growing rather fast) but remains less than 5 inches tall and 6 inches wide. It is surculose, the leaves are strongly triangulate relative to the more clearly lanceolate v-r, it has a strongly pronounced and relatively wide apical white band. While it was described as having a typically open rosette, and this plant has a rather congested rosette, Michael Bechtold's photos of plants at the type locality show some rather dense rosettes.

So, thoughts on fit within pintilla Vs. v-r? In many ways all I care about is that it is a really fine looking plant, but am intrigued by the possibility and the taxonomy (and mess thereof) of the v-r complex is fascinating to me.

[Gee.S]

You may have seen this, but just in case...

vrpintilla.jpg (117.93 KiB) Viewed 11993 times

[AGAVE_KILLER]

Thanks GeeS, I have. I think they did a great job and I really want to see the hybrids between salmiana and pintilla at the type locality. I also really like that they gave the lat/long for each type locality. I think Michael Bechtold's photos of the type locality plants are better and show a wider range of the variation in the plant.

I was hoping you would come down on one side or the other. The wide brush-stroke appearance of those markings really make me wonder . . .

[AGAVE_KILLER]

Also,

I would say this photo of a plant IDd by Walker as pintilla bears a strong resemblance.

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[Gee.S]

Dunno, but Greg may have collected that seed himself. You can always shake him down via PM if he misses this thread.

To me your plant has a rather airy look about it, ala A. nickelsiae, especially when compared to my own A. v-r, but then I wonder if the cause is largely environmental. Here's a snap from last year of one of my v-r youngins.

[AGAVE_KILLER]

Thanks GeeS.

Yes you are correct, my plant would be more open than yours because mine is growing in filtered Bright light (60% of day in full sun) in a rainforest and not in the blast furnace yours lives in. Even plants I have that are clearly v-r ssp. v-r are much more open. Here's a juvenile in the foreground.

311.JPG (211.27 KiB) Viewed 11983 times

Spoke with Greg -- at the time he couldn't recall but thought it came from a domestic source -- cultivated plant. But it was a rather brief exchange and the name pintilla was not explicitly used by either of us.

But if you look in Gentry his comparison of leaves clearly shows that what was classified as v-r at the time included examples of every separate species considered by Gonzalez-Elizondo 2011. So, if the plant serving as Greg's seed source was IDd as v-r in the 80s and flowered in the 2000s it could easily have been a plant that would have qualified for pintilla . . .

Would also note that the rather complex terminal spine (3 and 4 pronged pronounced terminal spines) on this plant and pintilla is much closer to what you see on nickelsiae than what you see on v-r.

[AGAVE_KILLER]

That wasn't such a good shot to illustrate my point -- GeeS, here is the same plant closer up for reference:

[Arizona Agave]

Here's a few of mine killer, a lot of these are from Greg as well. Martin

[AGAVE_KILLER]

Hey Martin,

Looking good, thanks for the shots -- that second one looks like it is kin to the one in question here, my smaller ones look just like it.

4th from the bottom has some pretty wicked terminal spines!

D.

[Arizona Agave]

You probably right killer. Martin

[MJP]

Agave Killer - your agave does look like "Agave pintilla".

I spent a good many hours in careful translation of the article that broke-up Agave victoriae-reginae into four taxa. You will find it below - sans photos.

Particular independent thought should be given to the results of the allozyme studies.

NOTE: Lamentably, the Table at the end of the work did not copy correctly and did not hold together when I corrected that error. ALSO, In copying the translation to this site nearly all special text features were lost, including italics. I began fixing this problem, but it was clear it would take rather a long time.

http://www.conabio.gob.mx/institucion/p ... e_%208.pdf" onclick="window.open(this.href);return false;

Acta Botanica Mexicana 95: 65-94 (2011)

THE AGAVE VICTORIAE-REGINAE COMPLEX (AGAVACEAE)

Authors: M. Socorro González-elizondo, Martha González-elizondo, irMa l. lópez-enríquez, lorenzore Séndiz-rojaS, jorGe a. tena-FloreS y Flor iSela retana-rentería (Instituto Politécnico Nacional, Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Unidad Durango Sigma 119, Fraccionamiento 20 de Noviembre II 34220 Durango, Durango, México herbario_ciidir@yahoo.com.mx)

ABSTRACT: The name Agave victoriae-reginae has been applied to a group of plants endemic to northern Mexico which are easily distinguished from other species of Agave by having leaves with corneous, entire margins, white lines on both faces and flowers with short, funnelform tubes. A taxonomic revision reveals that A. victoriae-reginae represents a complex of three species, one of them with two subspecies: 1a) Agave victoriae-reginae subsp. victoriae-reginae (western Nuevo León and eastern extreme of Coahuila; 1b) A. victoriae-reginae subsp. swobodae (southern Coahuila and northeastern Durango); 2) Agave nickelsiae (microendemic to southeastern Coahuila); and 3) Agave pintilla (the most westernly distributed species in the group, restricted to southeastern Durango). Agave pintilla is here described as new, the name of A. nickelsiae is reinstated, and A. victoriae- reginae is circumscribed. A key to the taxa as well as ammended descriptions for A. victoriae-reginae subsp. victoriae-reginae, A. victoriae-reginae subsp. swobodae and A. nickelsiae are provided. No natural hybrids were found among the taxa of the Agave victoriae-reginae complex but three natural hybrids with other species are recorded: Agave nickelsiae x A. asperrima, A. nickelsiae x A. lechuguilla, and A. pintilla x A. salmiana subsp. crassispina.

INTRODUCTION: The name Agave victoriae-reginae T. Moore (Agavaceae) traditionally has been applied to a group of endemic plants of northern Mexico, prized by collectors and growers due to its ornamental value. It is listed in the NOM-059-SEMARNAT-2010 as endangered species (Anonymous, 2010) and in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Agave victoriae-reginae is part of the subgenus Littaea for having an inflorescence without apparent branches branches and leaves with entire margins. It was included by Gentry (1982) in the group Marginatae that have horny leaf margins and flowers with short funnel-shaped tubes.

Under the name A. victoriae-reginae are included plants easily distinguishable from other species of Agave by presenting a unique combination of features: The name has been used generally for this group by many authors (eg Gentry, 1982;.. González Elizondo et al, 1991, 2009,. Ullrich, 1991b; Espejo and López-Ferrari, 1992; Garcia-Mendoza, 1995 2002, 2003; Chavez Avila and Martinez-Palacios, 1996; Eguiarte et al., 1999; Martinez-Palacios et al., 1999; Díaz Ramírez et al., 2004; Villarreal-Quintanilla, 2001; Villarreal-Quintanilla and Encina-Domínguez, 2005, among others). However, among the plants traditionally considered A. victoriae-reginae there are some that differ considerably in the way of the rosette, the number, shape and color of the leaves, the size and shape of the flowers and the habitat they occupy, recognized in this work are four taxa within the group.

MATERIALS & METHODS: A taxonomic revision of the plants that have been treated under the name of A. victoriae-reginae was performed, covering populations previously recorded and others detected for the first time during this work. We collected and systematized information on taxonomy, biology, genetics and population status. Collections in MSNA, CFNL, CIIDIR, ENCB, and UNL herbal MEXU were examined.

We performed16 sampling or prospecting excursions in the states of Nuevo Leon, Coahuila and Durango; for plants recorded in the field the following data were taken: diameter, height and number of leaves of the rosette; length, width and color of the leaves, and when present inflorescence height, diameter, number of branches shape and color of flowers. Where it was necessary to collect samples one herbarium sheet was prepared, and when they were present, samples of flowers and bracts, flowers were preserved in a solution of 70% alcohol and glycerine (Authorization License scientific collection of species populations at risk or critical habitat Job No. SGPA / DGVS / 03 368/09.). Vouchers are deposited in the herbarium CIIDIR.

Taxonomic revision of the components of the Agave victoriae-reginae complex was carried out by conventional methods of comparison of morphological, ecological and geographical characteristics. To award the correct names for taxa that were recognized we reviewed taxonomic and nomenclatural issues. The quote is based on the authors Villaseñor et al. (2008).

RESULTS & DISCUSSION: The taxonomic revision of the group reveals that what has been discussed previously under the name of A. victoriae-reginae is a complex of four taxa that differ substantially in the shape of the rosette, the number, shape and color of leaves, the size and shape of the flowers, habitat they occupy and the geographical distribution. The diagnostic characters are presented in Table 1 and the key to distinguishing taxa. Three species are recognized, one with two subspecies:
1. Agave victoriae-reginae T. Moore 1a. Agave victoriae-reginae T. Moore subsp. victoriae-reginae 1b. Agave victoriae-reginae subsp. swobodae J. J. Halda
2. Agave nickelsiae Goss. ex Rol.-Goss.
3. Agave pintilla S. González, M. González & L. Reséndiz All components of the complex are developed only on sedimentary substrates, mainly limestone and, to a lesser extent, on colluvium or conglomerate, rarely on sandstone.

In this paper the recognition of taxa is based on discrete morphological character differences, coupled with the environmental characteristics of habitats and geographical distribution of the four entities. Then the partial differences between the classification proposed here and the results of two molecular and phytochemical studies are discussed.

A comparison of the patterns of variation in 10 polymorphic allozyme loci GRAPHICS (Chavez Avila and Martinez-Palacios., 1996; Martinez-Palacios et al, 1999) indicates that the components of the complex Agave victoriae-reginae have high levels of genetic variation within populations and a particularly high level of differentiation between populations, to the extent that each appears to represent an independent evolutionary unit, with levels of differentiation comparable to those observed between different subspecies or even between species in many genera of plants (Martinez-Palacios et al., 1999).

This could be a point in favor to support the separation of taxa proposed in this paper, but it is not, for the three sets subjected to analysis of allozyme did not correspond to the taxa recognized here, particularly in the case of A. nickelsiae, which differs markedly from A. victoriae-reginae morphologically, but in the study of allozymes appears (like "population 3") with affinity with plants of A. victoriae-reginae subsp. victoriae-reginae (populations 1 and 2). This seems to indicate that this complex changes in allozymes followed an independent path to morphological differentiation.

A comparison of profiles ISTR (Ávila Sevilla, 2010) revealed polymorphism levels up to 100% in A. victoriae-reginae subsp. victoriae-reginae, suggesting a high genetic variability, but does not indicate a direct correlation between profiles and ISTR taxa recognized in this work except Agave pintilla, which is clearly separated from the pack (this species was not included in the allozyme study for it had not been discovered yet).

An analysis of foliar phenolic profiles (Avila Sevilla, 2010) indicates that in the complex A. victoriae-reginae phenolic acids predominate and secondly flavonoids, similarly to what was found by Almaraz-Abarca et al. (2009) to detect intra and interspecific variability in Agave durangensis and related species. As in the ISTR profiles, Agave pintilla is clearly differentiated from the rest of the group.

The paraphyla (“paraphilia”) molecular and phytochemical levels can occur for various reasons, among which are: a) asynchrony in evolution at the molecular, morphological (Hörandl, 2010) and biochemically, with morphological changes usually require more time to manifest; b) lack of congruence between phylogenies obtained for different genes (Gaut et al, 2000).; c) significant changes to speciation may reside in a few loci not detected by RAPD markers (Navarro-Quezada et al., 2003). Therefore, it is necessary to use complementarily information from molecular chloroplast, mitochondria and nucleus, in addition to morphological information.

In A. victoriae-reginae subsp. victoriae-reginae morphological variation within populations is also recorded, particularly in the form and color of the apex of the leaves and the type and size of the spine. Good-Avila et al. (2006) report that Agave is a young genus, between 7.8 and 10.1 million years of age, finding that it was in high stages of speciation: 6
to 8 million years ago and later between 2.5 to 3 million years. The diversity of phenotypes and habitats found for the complex of A. victoriae-reginae and the group's presence in areas which have suffered severe climatic changes during the Pleistocene, suggests an active process of speciation in the group. The recognition of the taxa that are part of the complex A. victoriae-reginae is a substantial advance in understanding the group and to facilitate conservation action, yet studies are required that combine morphological data with others based in phytochemistry, cytogenetics, molecular biology and phylogeography, and ecological work to improve knowledge about the variables that determine the distribution of taxa of the complex and other biology of populations that allow better interpretation of the morphological and demographic patterns in the group.

TAXONOMY:
Key to identify the taxa of A. victoriae-reginae complex:
1a) compact rosettes of green to lime, leaves densely imbricate, those of the middle part ascending or curved toward the central axis, truncate to rounded at apex, with spine mucroniforme, acicular or lanceolate; Flowers 2.6-3.6 cm long (3.5-7 cm including stamens) ..................................... 2
2a) globose to depressed-globose rosettes; lanceolate or narrowly oblong leaves, (7-) 10-22 cm long; in dry leaves the corneal margin is continuous to the apex - A. victoriae-reginae subsp. victoriae-reginae
2b) Rosettes oblong-globose; leaves narrowly oblong to narrowly triangular, 6-12 cm long; in dry leaves the corneal margin often is separated in the distal part - A. victoriae-reginae subsp. swobodae
1b) rosettes open or subcompact, color gray or pale green to bluish green, middle leaves ascending or divergent, not curved towards the axis of the plant, rounded to acute at the apex, with lanceolate or pyramidal spine; Flowers 3.8-4.4 cm long (7-8.8 cm including stamens) ........................... 3
3a) Leaves 170-280, those of the middle part of the plant ascending (subcompact rosesstes in mature plants) color gray green to dull green, puberulent, oblong, ventrally convex, somewhat narrowed near the base, apex rounded, decurrent spine on the corners of the leaf, apical white band 1 (-2) mm wide; flowers in groups of three tepals and filaments with purple staining - A. nickelsiae
3b) leaves 60-180, those of the middle part of the divergent plant (mature plants open rosette), bluish green to pale green, not puberulent, narrowly triangular, flat or concave ventrally, wider near the base, acute apex gradually continuous with the lanceolate spine, it is not - or is barely - decurrent, the white apical stripe 5-10 mm wide; flowers in groups of two, tepals whitish to greenish white, whitish filaments or with mild purple dye - A. pintilla

1. Agave victoriae-reginae T. Moore, Gardener's Chronicle, new series 4: 484, 1875. 485. Lectotype (designated by Ullrich, 1991). Fig. 101. Moore, 1875: 485.
The species name is dedicated to Queen Victoria (1819-1901) of England. The history of the description of this magnificent species, and the vain efforts of Carriere (1875, 1875b) to prioritize the name: A. consideranti, were discussed by Ullrich (1991b).
Since in the original description of A. victoriae-reginae no type was selected, the original artwork was designated (Ullrich, 1991) as the lectotype (Art. 9.2 IUCN), replacing the neotype designated by Gentry (1982) (Art. 9.11 IUCN ).

Rosette solitary or sometimes caespitose, rarely surculosa, stemless or stem not visible, compact, globose, depressed-globose or oblong-globose short stalk; leaves (70-) 200 to about 500, densely imbricate, green to lemon-green with narrow white bands on both sides and margins, rigid or flexible rarely lanceolate narrowly oblong, rounded or rarely keeled on the back, sometimes almost triangular in section, ventrally concave or conduplicate except towards the base where they present a thickening, 6-22 cm long, 1.5-4.8 cm wide; corneal margin, white or gray, 1.3 mm wide, entire, continuous margin to the base and to the apex or subsp. swobodae sometimes detached in the distal half; leaf apex truncate or rounded, rarely acute, highlighting the usually green or white band; terminal spine straight or twisted from very short and mucroniforme and acicular to subulate, rarely lanceolate, with wide or narrow base, 0.4-1.8 cm long, grooved or fluted top and keeled below, often accompanied with 1-3 short teeth crowning the blade angles, dark brown, dark gray or almost black; ascending or erect inflorescence, 1.5-4.3 m tall, dense flowers on the top half, the peduncle 1.6-6.6 cm in diameter, with deltoid papery bracts, largely attenuated towards the apex; flowers in groups of three or sometimes in pairs, on pedicels bifurcated or trifurcated short and thick, the perianth 2.6-3.6 cm long, creamy white, greenish white or pale gray-green, tepals sometimes with reddish tinge, ovary 1.3-1.7 cm long, thickly fusiform with short neck, funnel-shaped tube, 3.5 x 7.9 mm; tepals erect, spreading, subequal, 10-19 x 3-4 mm, widely linear somewhat conduplicate and embracing the filaments, interiors somewhat keel-shaped, rounded apex, filaments straight, 20-48 mm long, inserted on the edge of the tube, yellow anthers; capsules of a woody consistency or thickly leathery, oblong to narrowly oblong, (1.3-) 1.7-2.1 x 0.7-1.1 cm, rounded at base, shortly apiculate at the apex, leaflets oblong to narrowly oblong, 0.7-0.9 cm wide, on pedicels 2-5 mm; black seeds opaque or shiny, 5.3 x 2-3.5 mm, semicircular to lacrimiform, lattice-vein on both sides, margin low.

Agave victoriae-reginae develops on escarpments with steep slopes in the Sierra Madre Oriental in western Nuevo Leon and transverse ridges that cross Coahuila to the east of Durango, and on ridges crowning isolated hills in western Nuevo Leon and extreme eastern Coahuila and to a lesser extent on colluvium in piedmont. In desert scrub vegetation and submontane scrub.
We recognize two subspecies of A. victoriae-reginae based on habitat of the plant, the shape of the leaves, and the distribution of the allopatric taxa.

1a. Agave victoriae-reginae T. Moore subsp. victoriae-reginae. Agave considerati Carr., Rev. Hort. 429. 1875 f. 68. Not typified. Figs. 1a, 2b, 3b. Common names: lechuguilla (being clearly differentiated from the common lechuguilla), maguey noha, maguey de roca, noa, noha.

The leaves are usually strong, although populations of Bustamante, Mina and some of La Huasteca are flexible and thin, the young leaves markedly folded longitudinally.
Agave victoriae-reginae subsp. victoriae-reginae thrives on limestone escarpments of very steep (cliffs or "Relices") frequently vertical, in narrow canyons which form part of the Sierra Madre Oriental, subprovince Sierra Plegada in western Nuevo Leon as well as on limestone ridge capping low mountains in western Nuevo Leon and the extreme east of Coahuila, sometimes in colluvium in piedmont, between 564 and 1684 m asl (Fig. 5). The largest populations are found in the Huasteca Canyon (Gonzalez, 2008), part of the Parque Nacional Cumbres de Monterrey, primarily in xeric scrub on cliffs where predominate Agave bracteosa, A. lechu- guilla, A. striata, Hechtia spp. y Dasylirion berlandieri. On piedmont colluvium grows in desert scrub and submontane scrub of Helietta parvifolia, Cordia boissieri, Acacia farnesiana, A. amentacea, Celtis pallida, Havardia pallens, Aloysia gratissima, Leucophyllum texanum, Diospyros texana, Croton fruticulosus, Cylindropuntia leptocaulis, C. imbricata, A. lechuguilla, A. striata, Selaginella sp. and Wedelia hispida. In more sheltered places the submontane scrub presents saplings of Helietta parvifolia, Acacia berlandieri y Gochnatia hypoleuca. In the subregion of sierritas of the Chihuahuan Desert A. victoriae- reginae grows on the limestone walls of the ridges of low sierritas in communities of desert scrub, sometimes with elements of submontane scrub, highlighting Hechtia sp., Helietta parvifolia, Fouquieria splendens, Echinocereus sp. y Opuntia sp.

Specimens examined. MÉXICO, COAHUILA. Municipio Candela. Par- te sur de sierrita al SW de Candela, cerca del límite con Nuevo León, 26°44'22" N, 100°45'24" W, 570 m, en cresta caliza coronando sierrita, vertiente SW, 1 Jun 2010, L. Reséndiz 156, J. Noriega, S. González (CIIDIR). NUEVO LEÓN. Muni- cipio Bustamante. Sierrita de La Ventana, 26°34'40" N, 100°39'47" W, 700 m, M. González 4124, A. Torres, S. González (CIIDIR); ibid., 26°34'18" N, 100°39'29" W, 706 m, 31 May 2009, L. Reséndiz 128, A. Torres (CIIDIR, ENCB); ibid., 26°34'46" N, 100°39'58" W, 695 m, 31 May 2009, L. Reséndiz 129, A. Torres (CIIDIR, MEXU); ibid., L. Reséndiz 129b, A. Torres (CIIDIR); municipio Mina. Cerro de las Ventanas, 25°57'56" N, 100°36'7" W, 645 m, 8 May 2009, L. Reséndiz 116, M. González, S. González, L. López y F. Mercado (CIIDIR, ENCB, MEXU); ibid., L. Reséndiz 117, M. González, S. González, L. López y F. Mercado (CIIDIR); ibid., L. Reséndiz 118, M. González, S. González, L. López y F. Mercado (CIIDIR); municipio Santa Cata- rina. Cañón de la Huasteca (sitio 14), 25°39' N, 100°30' W, 7 May 2009, L. Reséndiz 115, M. González, S. González, L. López y F. Mercado (CIIDIR); ibid., frutos de otro individuo, L. Reséndiz 115-b (CIIDIR); Cañón de la Huasteca
(sitio 15.3), 25°38'34" N, 100°28'46" W, 807 m, 7 May 2009, L. Reséndiz 113, M. González, S. González, L. López y F. Mercado (CIIDIR); La Huasteca, Cañón de Ballesteros, 25°38'18" N, 100°27'9" W, 800 m, conglomerado, 16 Jun 2009, I. Cabral C. s.n. con investiga- dores de Santa Ana Bot. Garden (ANSM); Cañón de la Huasteca (sitio 15.5), 25°38' N, 100°28" W, 807 m, L. Reséndiz 114, M. González, S. González, L. López y F. Mercado (CIIDIR); Cañón de la Huasteca, km 4, 25°37'31" N, 100°27'36" W, 745 m, 30 May 2009, L. Reséndiz 125b, A. Torres (CIIDIR, ENCB); Cañón de la Huasteca, camino cerro El Panal por Cañón Guitarritas, 25°35'35" N, 100°31'1" W, 1180 m, 16 Dic 2006, I. Cabral C. 2308 e hijos (ANSM); Cañón de la Huasteca, después de la cortina, lado derecho, 25°33'43" N, 100°24'17" W, 873 m, 30 May 2009, L. Reséndiz 127, A. Torres (CIIDIR, ENCB); Cañón de la Huasteca, al NE de El Pajonal por el camino a Santa Catarina, 25°29'34" N, 100°23'8" W, 1450 m, sobre coluvión, 5 May 2009, L. Reséndiz 111, M. González, S. González, L. López y F. Mercado (CIIDIR, ENCB, MEXU); Cañón de la Huasteca, El Pajonal, 25°29'37" N, 100°23'9" W, 1432m, 30 May 2009, L. Reséndiz 126, A. Torres (CIIDIR, ENCB); Cañón de la Huasteca, km 4, 25°37'31" N, 100°27'36" W, 745 m, 30 May 2009, L. Reséndiz 125, A. Torres (CIIDIR, ENCB); Cañón de la Huasteca, 3 Jun 1967, J. Marroquín s.n. (MEXU); ibid., 24 May 1979, C. de León 19 (UNL(2)); ibid., end of dirt road at gravel pit, 2 Aug 1972, Lyle McGill 9472, R. Brown y D.J. Pinkava (ENCB); Cañón de la Huas- teca (sitio 6.2), 25°39' N, 100°30' W, 6 May 2009, L. Reséndiz 112, M. González, S. González, L. López y F. Mercado (CIIDIR).

1b. Agave victoriae-reginae subsp. swoboda J. J. Halder, Acta Mus. Richnov. Sect. Nat. 7(2): 71. 2000. Holotype: Mexico in the north, Coahuila, on the hills, stony places, not far from the village Parr, only calcarious soils, ca. 1800 m above the sea. PR no. JJH8504315, leg. J.J. Halder 10.4.1985. (n.v.). Fig. 1b, 2a, 3a.
Plants acaulescent or with a short stem covered with leaves, globose to sub-columnar oblong (keg shaped) when mature, compact, 20-35 cm in diameter, up to 35 cm high, with 70 to approx. 180 leaves; narrowly oblong leaves to narrowly triangular, 6-12 cm long and 1.5-4.5 cm wide, ventrally flat to concave near the base, in dry leaves the horny margin continued to the apex or frequently detached in the distal part; inflorescence 1.6-4.3 m high; flowers with perianth 2.6-3.2 cm long, tube greenish white collar, tepals white pink or reddish in the inner part, filaments and style pale purple Rose, anthers pale yellow; capsules tightly oblong, 1.7-1.9 x 0.7-0.9 cm, valves 0.7-0.8 cm wide, seeds 3 x 2 mm.
Agave victoriae-reginae subsp. swobodae was described (Halda, 2000) based on plant habit and having flowers and seeds "bigger". Although the size of the flowers is within the variation that occurs in A. victoriae-reginae subsp. victoriae-reginae and seeds of the subspecies swobodae are smaller, recognition of this subspecies is accepted according to the criteria of Haig et al. (2006) for discretion in the characters and separation of populations.

Agave victoriae-reginae subsp. swobodae is found on escarpments of the extensions of the Sierra Madre Oriental through the Chihuahuan Desert (“Serranias Transversales”) in southern Coahuila and east of Durango, on limestone, rarely on colluvium of foothills, between 865 and 1550 m s.n.m. (Fig. 5). In desert scrub in the prevailing Hechtia texensis, H. podantha, Agave Lechuguilla, A. striata, A. asperrima, Yucca rigida, Fouquieria splendens, Opuntia rufida, Euphorbia antisyphilitica, Echinocereus sp., Jatropha dioica and Dasylirion sp. On sites with colluvium at the base of cliffs the desert scrub has mixed elements of submontane scrub mainly Acacia berlandieri and Gochnatia hypoleuca.

Specimens examined. MÉXICO, COAHUILA. Municipio San Pedro de las Colonias. Al NE de San Pedro de las Colonias, por la carretera a Cuatro Cié- negas, 26°8'37" N, 102°44'38" W, 1044 m, base de riscos en el tercio inferior del cerro, 1 Jun 2010, L. Reséndiz 155, J. Noriega (CIIDIR); municipio Viesca. Cerro de las Noas en el cañón de Ahuichila; camino de Viesca a Ahuichila, 25°11'24" N, 102°38'59" W, 1292 m, escarpe, 12 Ago 2009, L. López 594, T. Tapia y M. Gon- zález (CIIDIR); ibid., 25°11'15" N, 102°39'2" W, 1262 m, escarpe exposición E, 12 Ago 2009, L. López 594b, T. Tapia y M. González (CIIDIR); Cañón de Ahuichila, 1250 m, ladera calcárea, 22 Ago 1991, J. I. Calzada 17379, C. Toledo y J. Blando (MEXU-2); Frentón de Ahuichila, ca 6.5 km al SW de Ahuichila, 25°4'30" N, 102°40'20" W, sobre escarpes, 12 Ago 2009, J. Tapia s.n., S. Tapia, T. Tapia, M. González (CIIDIR); Sierra del Mármol, 28 km al S de Viesca, camino a Ahuichi- la, 3 km al S del rancho, 1300 m, ladera caliza, 21 Jun 1994, A. García-Mendoza 5961, S. Franco y J. Reyes (MEXU); Sierra del Mármol, 28 km al S de Viesca, camino a Ahuichila, 1300 m, ladera caliza, 30 Ago 2000, A. García-Mendoza 6955 (MEXU). DURANGO. Municipio Lerdo. Picacho de León Guzmán, 25°30'28" N, 103°40'13" W, 1211 m, 13 Ago 2009, L. López 598, M. González (CIIDIR); Cañón Fernández, aprox. 2.5 km al N de la entrada por el Cañón del Borrego, 25°19'33" N, 103°44'7" W, 1250 m, en risco sobre ladera caliza, 9 Dic 2003, L. Reséndiz 15, R. Galván, L. López, S. González y M. Pinedo (CIIDIR, ENCB); ibid., 14 May 2008, L. Reséndiz 108 M. González, S. González, L. López (CIIDIR, ENCB, IEB, MEXU); ibid., 2 km al N de Graceros, por el camino a la presa Francisco Zarco, 25°16'10" N, 103°45'5" W, 1450 m, sobre risco, 12 May 2008, L. López 530, F. Mer- cado y D. Ramírez (CIIDIR, ENCB, IEB, MEXU); Cañón Fernández, ca. 2 km al S de Graceros, ladera del Cerro Mulato, 25°14'23" N, 103°44'22" W, 1267 m, L. Reséndiz 150, M. González y L. López (CIIDIR); Graceros, 2 km adelante, 13 km al E de la desviación a la presa Fco. Zarco, 1200 m, ladera caliza, 22 Jun 1994, A. García- Mendoza 5965, S. Franco y J. Reyes (MEXU).

2. Agave nickelsiae Goss. Rol. ex-Goss., Hort. Amer. former Rev. Hortic. (Revue Horticole): 579. 1895 (sub 'nickelsi'). Agave victoriae-reginae T. Moore f. nickelsiae (Rol.-Goss.) Trel., Contr. U. S. Nat. Herb. 23: 140. 1920. Neotype (designated by Breitung, 1960): Figure 53, p.. 26, vol. 32 in Cact. Succ. J. (Los Angeles). 1960. Figs. 1c, 2c, 3c. Agave victoriae- reginae var. laxior Berger, Hort. Mortol., 15, 364. 1912. Agave ferdinandi-regis A. Berger, Die Agaven, Beiträge zu einer Monographie 90. 1915. Type designated by (plant shown in
the Paris Exhibition of 1900 with several others in Mexico and then Nabonnand Garden, where Berger received it in 1903).

The species name was dedicated in honor of Mrs. Anna B. Nickels, horticulturist of Texas who came to know (“que dio a conocer”) the plant.
Common name: not registered during this field work. The designation of "pintilla" is recorded for the species in a manifestation of environmental impact (Anonymous, 2007); Trelease (1920) cites in turn the name "pintillo" same that applied in Durango for A. pintilla.

Rosettes caespitose, rarely solitary, not surculose, stemless or with a short stem not visible (covered with leaves), up to 75 cm diameter and 65 cm high, subcompact or open; 170- 280 leaves, of color grayish green to dull green, with white bandson both sides and margins, puberulent, oblong, gradually narrowed towards the apex, not curved toward the center of the plant, dorsally keeled near the apex or the distal half of the abaxial surface, ventrally concave towards the base except where they are thick and markedly convex to keeled, 13- 23 cm long and 5.5-8.5 cm wide; corneal margin, white, 3-5 mm wide, entire, continuous margin to the base and to the apex or sometimes detached in the distal half; apex of the leaf rounded, apical white band inconspicuous, 1 (-2) mm wide, highlighting the black color of the spine; spine of color almost black, pyramidal to lanceolate, thick, 2-2.8 cm long, widely grooved above and roundly keeled below, the base wide and markedly decurrent on the corners of the leaf, usually with 3 adjacent teeth that crown the angles of the leaf; inflorescence erect, dense, the peduncle robust, 4.5-6.5 m high and up to 6.5 cm in diameter, with papery bracts deltoid on the base, linear, long attenuated towards the apex; flowers usually in groups of three on short and thick trifurcated pedicels, perianth 4-4.4 cm long, ovary 1.8-2.1 cm long, thickly fusiform, with short neck, funnel-shaped tube, 3-5 x 8-9 mm; tepals spreading, subequal, 18-22 x 4-6 mm, broadly linear, flat towards the apex, the interior somewhat keel-shaped, embracing the filaments only in its proximal half, the distal portion flat, dull to shiny, with purple staining the apex rounded, filaments straight, 60-66 mm long, with purple staining, inserted on the edge of the tube, anthers yellow, 11-14 mm long; capsules and seeds unknown.

Agave nickelsiae presents a clear preponderance of clonal propagation by rhizomes and low sexual reproduction: during 2009 no plants were observed with inflorescence nor evidence to initiate flowering, although dry scapes of A. nickelsiae x A. asperrima were found; in May 2010, a few individuals of A. nickelsiae were found flowering.
A. nickelsiae name has been cited as a synonym of A. victoriae-reginae or, when it is recognized as a separate species, under the name A. ferdinandi-regis. However, the revision of the original description of A. nickelsiae reveals that this is a legitimate and valid name for the taxon. The neotype designated by Gentry (1982) for A. victoriae-reginae (designated lectotype replaced by Ullrich, 1991), corresponds to a plant A. nickelsiae: 12-16 miles NE of Saltillo, Coahuila, along road to Monterrey, June 10-July 5, 1963; elev. 4000-5000 feet, shrub and succulent desert on limestone, Gentry, Barclay & Arguelles 20043 (DES, MEXU,
US).

Agave nickelsiae restricted distribution southeast of Coahuila, in the region Arteaga- Ramos Arizpe (Fig. 5) on “rúdico” conglomerate hillocks with soil and abundant limestone fragments protruding from the surface. The predominant soils are calcaric regosol (when exceeding 10 cm deep) and calcaric leptosol. It is found particularly on the edges of the top of the hills, between 1500 and 1690 m. In xeric scrubland of plant associations dominated by: a) Tiquilia canescens y otras boragináceas, Mimosa sp., Agave asperrima x A. nickelsiae, A. lechuguilla con escasas Fouquieria splendens, Vi- guiera stenoloba, Larrea tridentata y Lophophora williamsii; b) Agave lechuguilla, Buddleja marrubiifolia, Agave striata, Hechtia sp., Dasylirion sp. y escasa Larrea tridentata; c) Parthenium incanum, Buddleja marrubifolia, Aristida sp., asteráceas, Larrea tridentata y Opuntia leptocaulis.
The area where A. nickelsiae is located is subject to a high degree of disturbance by urbanization, banks of materials, motorcycle practices and road building, causing strong fragmentation of the habitat.

Specimens examined. MÉXICO, COAHUILA. Municipio Ramos Arizpe. Ramos Arizpe, sitio 4, 25°31'0" N, 100°53'28" W, 1502 m, 10 May 2009, L. Reséndiz 123, M. González, S. González, L. López y F. Mercado (CIIDIR, ENCB, MEXU); Ramos Arizpe, al SE, sitio 1-3, 25°30'38" N, 100°54'4" W, 1502 m, en ladera de loma, 10 May 2009, L. Reséndiz 124, M. González, S. González, L. López y F. Mercado (CIIDIR); Ramos Arizpe, cerca de sitio 2-3, 25°30'37" N, 100°53'36" W, 1520 m, 9 May 2009, L. Reséndiz 121, M. González, S. González, L. López y F. Mercado (CII- DIR); rancho El Saucillo de Abajo, al SE de Ramos Arizpe, 25°30'8" N, 100°54'36" W, 1530 m, en parte alta de loma, 2 Jun 2010, L. Reséndiz 159, J. Noriega, S. Gonzá- lez, T. Espinoza Hernández (CIIDIR); predio al lado del rancho El Saucillo de Abajo, al SE de Ramos Arizpe, 25°29'54" N, 100°54'46" W, 1537 m, en margen NW de loma, 2 Jun 2010, L. Reséndiz 158, J. Noriega, S. González, T. Espinoza Hernández (CIIDIR); Agave nickelsiae x A. lechuguilla, ibid., 25°29'43" N, 100°54'43" W, 1530 m, 2 Jun 2010, L. Reséndiz 157, J. Noriega, S. González, T. Espinoza Hernández (CIIDIR); vicinity of Saltillo, A. nickelsiae x A. asperrima, 1 Feb 1952, H. S. Gentry 11530 (MEXU); ibid., A. nickelsiae x A. asperrima, Jun 10-Jul 5 1963, H. S. Gentry 20044, Barclay y Argüelles (MEXU-2). Municipio Arteaga. Loma Alta, al N de Ar- teaga; Sitio 5-4, 25°28'31" N, 100°51'38" W, 1688 m, 9 May 2009, L. Reséndiz 119, M. González, S. González, L. López y F. Mercado (CIIDIR).

3. Agave pintilla S. González, M. González & L. Reséndiz, sp. nov. Figs. 1d, 2d, 3d, 4a-f. Agave victoriae-reginae T. Moore et A. nickelsiae Goss. ex Rol.-Goss. affinis sed rosulis apertis laxis, foliis anguste triangularibus, pallidioribus vel glauco-viridibus, inflorescentia laxiore et floribus geminatis differt. Ab A. victoriae-reginae differt rosulis caespitosis, foliis basi latioribus et floribus majoribus; A. nickelsiae valde affinis sed habitu breviore, foliis minus numerosis, non puberulentis, floribus lobis albidis vel albido-viridibus differt.
Type: MEXICO, Durango: municipality of El Mezquital, approx. 0.3 km (straight line) to the N of the junction with the road to Agua Zarca, the road W of Durango - El Mezquital, 23 ° 30'49 "N, 104 ° 23'39" W, 1444 m above sea level, on slope, desert scrub with elements of subtropical thicket (Fouquieria splendens, Jatropha dioica, Ipomoea murucoides) 131 L. Resendiz, L. López, F. Mercado and L. Chavez (holotype: CIIDIR; isotypes: ENCB, MEXU).
Common names: pintillo maguey, pintillo. (the painted maguey)

Rosettes caespitose or solitary, not surculose, stemless, 30-60 cm in diameter and 20-35 cm high, lax, open; 60-180 diverging leaves, pale green to bluish green, with white stripes on both sides and margins, narrowly triangular, gradually narrowed towards the apex, most Wide near the base, dorsally rounded or keeled near the apex, ventrally concave or flat to the base, 13 to 22 cm long and 5.8-8 cm wide; corneal margin, white, 3-5 mm wide, entire, continuing to the base and to the apex or terminating 2-3 cm below the apex; apex of leaf sharp, highlighting the white apical band 5-10 mm wide; spine of color almost black, narrowly pyramidal to lanceolate, 2-2.9 cm long, amply grooved on top and keeled below, not or very slightly decurrent on the angles of the leaf, usually with 3 adjacent teeth that crown angles of the leaf or at least with one dorsal spine shorter; inflorescence erect, relatively lax, the peduncle 1.6-4.3 m high and up to 4.5 cm in diameter, with papery bracts deltoid, long attenuated towards the apex; flowers in pairs, on bifurcated pedicels, perianth 4-4.4 cm long, ovary 1.8-2.1 cm long, thickly fusiform, greenish, with short neck, funnel- shaped tube, 3-5 x 8-10 mm; tepals ascending to “patentes”, subequal, 18-22 x 5-7 mm, wide, linear some conduplicate and embracing the filaments at the base, flat towards the apex, the interior somewhat keel-shaped, the apex rounded, whitish to greenish white, filaments greenish-white or with purple staining, straight, 58-66 mm long, inserted on the edge of the tube, anthers creamy yellow, 11-15 mm long; woody capsules, broadly oblong, 2.2-2.4 x 1.6-1.8 cm, rounded at the base, very shortly apiculate, valves suborbicular, 1.4- 1.5 cm wide, on thick pedicels 2-4 mm long; seeds black, shiny or dull, 4-5 x 2.5-4 mm, suborbicular, semicircular or lacrimiform, reticulated-veins on both sides, the margin low.

Agave pintilla is known only from southeast of Durango, in the township of El Mezquital in the foothills of the Sierra Madre Occidental (Fig. 5), between 1440 and 1580 m s.n.m. It is the species of westernmost distribution within the complex. Although the area where it grows is located towards the eastern slope of the Sierra Madre Occidental, A. pintilla is the only species of the A. victoriae-reginae complex that develops in a watershed that drains into the Pacific. It grows on hillocks of unconsolidated conglomerate in a predominantly volcanic area, where mixed igneous rock fragments may be found. The dominant soils are calcaric regosols with abundant CaCO3 and poor drainage due to the presence of a “ócrica”, hard and crusty layer. In desert scrub of relict type surrounded by subtropical thicket and in subtropical thicket in the following associations: a) Fouquieria splendens, Myrtillocactus geometrizans, Prosopis laevigata y Cercidium sp., con frecuencia con Jatropha dioica, rara vez con Agave durangensis; b) P. laevi- gata, M. geometrizans, Cercidium sp., Lycium sp., F.
splendens e Ipomoea murucoi- des; c) F. splendens, J. dioica, I. murucoides, L. graveolens; d) Acacia neovernicosa, Krameria sp., Atriplex sp. y F. splendens con Euphorbia antisiphylitica, J. dioica, Cylindropuntia leptocaulis, Agave durangensis, Agave cf. salmiana, Eysenhardtia sp. y M. geometrizans o con I. murucoides, Tecoma stans y L. graveolens.

Agave pintilla presents reproduction sexually by seed and asexually by rhizomes, making it the second most common, plants in dense colonies or loosely grouped. The fact that mature individuals of A. pintilla have an appearance similar to that of younger individuals in some populations of A. victoriae-reginae subsp. victoriae-reginae, coupled with disjunct distribution of relict type in A. pintilla and the small size of their populations (resulting in part from its restriction to sedimentary substrate in an area with a prevalence of igneous substrate) can be interpreted that A. pintilla has evolved at a slower rate than A. victoriae- reginae as a result of fewer individuals, less diversity of habitats available and less opportunity for genetic exchange. The comparison of ISTR profiles between populations of group A. victoriae-reginae (Ávila Sevilla, 2010) shows that the low complexity sequences with five and six, respectively, is presented precisely in species with very small populations: A. nickelsiae and A. pintilla, which seems to support the hypothesis of limited genetic exchange.
The specific epithet refers to the common name, “pintillo” (which means “painted”), with which this plant is known due to the obvious white stripes of the leaves.
Despite its small size, the plant was used until about 15 years ago to produce mezcal, prized for having a delicate flavor. Like the other taxa of A. victoriae-reginae complex, A. pintilla has a high potential as an ornamental because of its symmetry, relatively small size and attractive appearance.

Specimens examined: MÉXICO, DURANGO. Municipio El Mezquital. Los Pérez, al W, por el camino al ejido Santa Gertrudis, 23°32'45" N, 104°23'35" W, 1482 m, en conglomerado muy intemperizado, blanco,13 Jun 2010, S. González 7650, M. González, L. Reséndiz, L. Pánuco (CIIDIR); Agua Zarca, aprox. 0.3 km (línea recta) al N del entronque con el camino a Agua Zarca, al W de la carretera Durango - El Mez- quital, 23°30'49" N, 104°23'39" W, 1444 m, 15 Jun 2009, L. Reséndiz 131, L. López, F. Mercado y L. Chávez (CIIDIR, ENCB, MEXU); Agua Zarca, al E, aprox. 0.2 km al S del entronque, al W de la carretera Durango - El Mezquital, 23°30'37" N, 104°23'43" W, 1460 m, 4 Jun 2010, L. Reséndiz 160, J. Noriega, S. González (CIIDIR); Agua Zarca, aprox. 2 km al E, al W de la carretera Durango - El Mezquital, 23°30'36" N, 104°23'42" W, 1453 m, en ladera de loma, 10 Dic 2003, L. Reséndiz 1 (CIIDIR, ENCB); ibid., L. Reséndiz 16, R. Galván, L. López, M. Pinedo, J. L. y S. González (CIIDIR, ENCB); ibid., 1450 m, s/fecha, L. Reséndiz s.n. (ANSM, CFNL, MEXU); ibid., 15 Jun 2009, L. Reséndiz 130, L. López, F. Mercado y L. Chávez (CIIDIR); El Troncón, 2 km al W, por el camino a Temohaya, 23°30'06" N, 104°24'48" W, 1490 m, ladera de loma, exp N, 9 Dic 2010, S. González, M. González y L. Ruacho s.n. (CIIDIR).

Hybridization
During this work natural hybrids were not detected between taxa of the complex Agave victoriae-reginae or between A. victoriae-reginae subspecies with other species. References to hybrids of A. victoriae-reginae found in the literature (Gentry, 1982, among others), are based on abundant hybrids of A. nickelsiae with A. asperrima, or with A. lechuguilla. A high diversity of natural hybrids in a population of Agave victoriae-reginae subspecies reported by Verduzco-Martinez et al. (2009) for a site in the Cumbres de Monterrey National Park wherein involved A. lechuguilla, A. bracteosa, and A. americana (A. asperrima?) could be a very local situation.

A summary of the frequency of natural hybridization in species complex A. victoriae- reginae is presented in Table 2. The data are based on observations in the field in relation to the number of individuals parental and hybrid (number of colonies in the case of A. nickelsiae) and will not necessarily be the same in hybridization experiments.

For the size, extent and health of their populations, A. victoriae-reginae subspecies do not hybridize with other species or do it in a very low frequency. Moreover, in A. nickelsiae a high incidence of this phenomenon is observed, particularly with Agave asperrima Jacobi and Agave lechuguilla Torr., being greater than the first frequency to the second, contrary to what might be expected, since A. asperrima belongs to the subgenus Agave and not to the subgenus Littaea where A. nickelsiae is located. Hybrids with A. asperrima presented in turn reproduction asexual and sexual, some inflorescences were found to be intermediate between the two subgenera (Fig. 6). The high frequency of crossing A. nickelsiae with A. asperrima and with A. lechuguilla may be the result, at least partially, to the intense pressure of grazing by wild herbivores and strong disturbance which is subjected to their habitat. The relationship between the incidence of hybrids and the disturbance of the environment has been discussed by Stebbins (1957) and Grant (1971). Other cases of high occurrence of this phenomenon in Agave in high disturbance sites are presented in González Elizondo et al. (2009). Hybrid swarms mentioned by Gentry (1982) for A. nickelsiae (discussed in his work under the name of A. victoriae-reginae) are rare and predominate colonies of clones originated by crossing plants.

Hybrids between A nickelsiae and A. asperrima are described under the following names: (a) Agave nigra = Agave asperrima Jacobi x A. nickelsiae (acc. Kolendo, 2009, with A. nickelsiae cited as A. victoriae-reginae); (b) Agave pumila De Smet ex Baker, Amarillideae handbook, 172. 1888 = Agave asperrima x A. nickelsiae. Agave pumila, known only in cultivation, presents a marked dimorphism, with juveniles with leaves very short and wide (Gentry, 1982). Its origin has been interpreted as a hybrid between A. lechuguilla and A. nickelsiae (cited as "A. victoriae-reginae east of Saltillo.") (Gentry, op. cit.), but the image of a mature plant in the same work (p. 176) with the bases of the leaves thick and wide indicates affinity with A. asperrima; (c) Agave saltilloensis = A. asperrima x A. nickelsiae (acc. Kolendo, 2009, citing A. nickelsiae as A. victoriae-reginae); (d) Agave victoriae-reginae f. viridis Breitung, Cact. Succ. J. (Los Angeles) 32: 37. 1960 (without white stripes) = A. nickelsiae x A. lechuguilla, acc. Alsemgeest et al. 2007).

Specimens examined: a) Agave nickelsiae x A. asperrima. MÉXICO, COAHUILA. Ramos Arizpe, rancho El Saucillo de Abajo, al SE de Ramos Arizpe, 25°30'7" N, 100°54'36" W, 1541 m, matorral xerófilo con boragináceas, Mimosa, Fouquieria splendens, Viguiera stenoloba, Larrea tridentata, Lophophora william- sii, en loma de conglomerado con caliza; abundante, forma colonias, 2 Jun 2010, S. González s.n., L. Reséndiz, J. Noriega, T. Espinoza Hernández (CIIDIR); Ramos Arizpe, sitio 1-3, 25°30'38" N, 100°54'4" W, 1502 m, matorral xerófilo con Par- thenium incanum, Buddleja marrubifolia, Aristida, asteráceas, Larrea tridentata, Opuntia leptocaulis, en ladera de loma, conglomerado pedregoso, abundante, forma colonias, 10 May 2009, S. González fotografía, M. González, L. Reséndiz, L. López y F. Mercado. b) Agave nickelsiae x A. lechuguilla. MÉXICO, COAHUILA. Arteaga, Loma Alta, al N de Arteaga, 25°28'32" N, 100°51'38" W, 1690 m, matorral xerófilo con Agave lechuguilla, Buddleja marrubiifolia, Agave striata, Hechtia sp., Dasylirion sp., escasa Larrea tridentata, en ladera de loma caliza con conglomerado; abun- dante, forma colonias, 9 May 2009, S. González s.n., M. González, L. Reséndiz, L. López, M. Mercado (CIIDIR); Ramos Arizpe, predio al lado de Rancho El Saucillo de Abajo, al SE de Ramos Arizpe, 25°29'43" N, 100°54'43" W, 1530 m, matorral xe- rófilo con boragináceas, Mimosa, Fouquieria splendens, Viguiera stenoloba, Larrea tridentata, Lophophora williamsii, en loma de conglomerado con caliza; escasa, en pequeña colonia, 2 Jun 2010, L. Reséndiz 157, J. Noriega, S. González, T. Espinoza Hernández (CIIDIR). c) Agave pintilla x A. salmiana ssp. crassipina. For A. pintilla was recorded one event of hybridization, and this is with Agave salmiana Otto ex Salm-Dyck subsp. crassispina (Trel.) Gentry. The hybrid has the bright green, broad leaves A. salmiana but with a corneal margin, very small teeth, and almost undetectable white bands (Fig. 6). Specimen reviewed: Agave pintilla x Agave salmiana subsp. crassispina: MEXICO, DURANGO. Municipio El Mezquital. Los Perez, W, in the ejido Santa Gertrudis, N of the Crossed Mesa, 23 ° 32'49 "N, 104 ° 25.0 'W, 1574 m, very weathered conglomerate L. Resendiz 161 M . Gonzalez (CIIDIR).

It has been suggested that due to recent origins of many species of Agave s.l., the hybridization and introgression between species makes it difficult to resolve their phylogenetic relationships (Rocha et al., 2006). The remarkable morphological variation within and between populations presented by A. victoriae-reginae subspecies is derived rather from the plasticity of their phenotype and their high genetic variation.

Other names registered for the A. victoriae-reginae complex Names that correspond to forms or cultivars obtained for ornamental purposes: Agave victoriae-reginae f. dentata Breitung, Cact. Succ. J. (Los Angeles) 32: 35. 1960. Agave victoriae-reginae f. latifolia Breitung, Cact. Succ. J. (Los Angeles) 32: 37. 1960. Agave victoriae-reginae f. longifolia Breitung, Cact. Succ. J. (Los Angeles) 32: 38. 1960. Agave victoriae-reginae f. longispina Breitung, Cact. Succ. J. (Los Angeles) 32: 37. 1960. Agave victoriae-reginae f. ornata Breitung, Cact. Succ. J. (Los Angeles) 32: 37. 1960. Agave victoriae-reginae f. stolonifera H. Jacobsen, Kakteen Sukk. 11(6): 91, fig. 1960 (nom. inval., Art. 37.1) (Eggli, 2003). Agave victoriae-reginae f. variegata hort. (s.a.) (nom. inval., Art. 29.1) (Eggli, Agave victoriae-reginae var. compacta hort. (s.a.) (nom. inval., Art. 29.1) (Eggli, 2003). Agave victoriae-reginae var. stolonifera hort. (s.a.) (nom. inval., Art. 29.1) (Eggli, 2003).

Acknowledgments
Muchas personas contribuyeron con información sobre las plantas estudiadas. Los Srs. Santiago Cantú, Tomás Espinoza Hernández, Jesús Tapia, Santiago Tapia y Tomás Tapia, Ascensión Medrano y Luis Pánuco nos guiaron en la búsqueda de poblaciones. En campo y gabinete contamos con el valioso apoyo del Sr. Abraham Torres Soto, Biól. Fermín Mercado Muñoz, Sr. Marcos Pinedo Reyes, Sr. Jorge No- riega Villa y M. en C. David Ramírez Noya. Los Srs. Roberto González Elizon- do y Noé González Elizondo proporcionaron apoyo logístico. El Dr. Glafiro Alanís
90González-Elizondo et al.: El complejo Agave victoriae-reginae (Agavaceae) Flores, Dr. Carlos Velazco Macías, Dr. Ismael Cabral Cordero, M. en C. Georgina A. Tena González, Biól. Yamil López Bujdud, Biól. Federico Casillas Orona, Biól. Milton Ruiz, Dra. Raquel Galván Villanueva, Dr. Celso Manuel Valencia Castro, Dr. Francisco Valdés Perezgasga y Dr. Urs Eggli aportaron información sobre el grupo de estudio. El Ing. Felipe Lucio y el Dr. Alejandro Espinoza Treviño ayudaron a hacer contacto con personas que conocen poblaciones de A. victoriae-reginae. La Biol. Lizeth Ruacho González, Sergio Heines Silerio y Sra. Olivia Carvajal Pala- cios apoyaron en el manejo de imágenes. A los curadores de los herbarios ANSM, CFNL, CIIDIR, ENCB, MEXU y UNL se agradecen las facilidades para consulta de muestras. Un agradecimiento especial al Dr. Abisaí García Mendoza por compartir generosamente su conocimiento sobre la taxonomía del grupo, al Ing. Noel Herrera Pedroza por el profesional apoyo en la elaboración de la cartografía, al Dr. William R. Anderson por la orientación para resolver embrollos nomenclaturales y a dos re- visores anónimos que aportaron sugerencias que permitieron mejorar el manuscrito. Agradecemos a la Comisión de Operación y Fomento de Actividades Académicas (COFAA) del Instituto Politécnico Nacional (IPN) los estímulos a la investigación. El IPN (proyecto 20090766) y Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO, proyecto HS001) aportaron el financiamiento para el desarrollo del trabajo.

Table 1. Comparison of some morphological characters of Agave victoriae-reginae subsp. victoriae-reginae (A vr vr), A. victoriae-reginae subsp. swobodae (A v-r swob), A. nickelsiae, and A. pintilla.

A v-r v-r A v-r swob A. nickelsiae A. pintilla
Rosette (form) compact, compact subcompact open
globose to depressed oblong-globose or open
# Leaves (150-)280-500 70-180 170-280 60-180
Leaf Color green to lemon-green green grey-green to pale bluish-green
opaque-green
Leaf surface bald bald puberulent puberulent
Leaf length (cm) (7-)10-22 6-12 13-23 13-22
Leaf width (cm) 3.6-4.8 1.5-4.5 5.5-8.5 5.8-8
Leaf form lanceolate to stretched-oblong oblong narrowly triangular
stretched-oblong to narrowly
triangular
Perianth length (cm) 2.6-3.6 2.6-3.2 4-4.4 4-4.4
Filament length (cm) 20-48 20-30 60-66 58-66


LITERATURE CITED - Almaraz-Abarca, N., E. A. Delgado-Alvarado, V. Hernández-Vargas, M. Ortega-Chávez, G.
Orea-Lara, A. Cifuentes-Díaz de León, J. A. Ávila-Reyes y R. Muñiz-Martínez. 2009. Profiling of phenolic compounds of somatic and reproductive tissue of Agave durangensis Gentry (Agavaceae). Amer. J. Appl. Sci. 6: 1076-1085.
- Anónimo. 2010. Norma Oficial Mexicana NOM-059-ECOL-2010. Protección ambiental - Especies nativas de México de flora y fauna silvestres - Categorías de riesgo y especificaciones para su inclusión, exclusión o cambio - Lista de especies en riesgo. Secretaría de Medio Ambiente y Recursos Naturales. Diario Oficial de la Federación. México, D.F. 40 pp.
- Anónimo. 2007. Manifestación de impacto ambiental. Modalidad regional. Libramiento norponiente Saltillo - Autopista Saltillo - Monterrey, tramo entronque Monclova II- límite estatal Coahuila/Nuevo León. Consultoría y Proyectos de Carreteras, S.A. de C.V. 301 pp.
- Alsemgeest, W., J. Roosbroek y T. Walderveen. 2007. Agave victoriae-reginae T. Moore. Translation from Succulenta 86(2): 63-69 http://www.agaves.nl/Articles/E_" onclick="window.open(this.href);return false; victoriae%20reginae.htm (consultado 11 Dic. 2009).
- Ávila Sevilla, Z. E. 2010. Caracterización molecular y química de Agave victoriae-reginae T. Moore (Agavaceae). Tesis maestría en ciencias (Gestión Ambiental). Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Instituto Politécnico Nacional, Unidad Durango. Durango. pp.
- Carriere, E. A. 1875a. Chronique horticole: L’Agave victoriae-reginae. Rev. Hort. 47(21): 401. Carriere, E. A. 1875b. Agave consideranti. Rev. Hort. 47(22): 427-430. Chávez Ávila, V. M. y A. Martínez-Palacios. 1996. Evaluación genética y demográfica de Agave victoriae-reginae T. Moore y aplicación del cultivo de tejidos para su conservación. Universidad Nacional Autónoma de México. Bases de datos Sistema Nacional de Información sobre Biodiversidad de México - Comisión Nacional para el Conocimiento y Uso de la Biodiversidad. Proyecto No. B147. México, D.F.
- Díaz Ramírez, B., G. González Cervantes, J. A. Cueto Wong, A. Flores Hernández e I. Sánchez Cohen. 2004. Morfología de plántulas de Noa (Agave victoriae-reginae) analizadas por imagen como estudio de aproximación. Agrofaz 4(2): 649-656.
- Eguiarte, L. E., J. Larson-Guerra, J. Nuñez-Farfán, A. Martínez-Palacios, K. Santos del Prado y H. T. Arita. 1999. Diversidad filogenética y conservación: ejemplos a diferentes escalas y una propuesta a nivel poblacional para Agave victoriae-reginae en el desierto de Chihuahua, México. Rev. Chil. Hist. Nat. 72: 475-491.
- Eguiarte, L. E., A. Castillo y V. Souza. 2003. Evolución molecular y genómica en angiospermas. Interciencia 28(3): 1-8.
- Espejo, A. y A. R. López-Ferrari. 1992. Las monocotiledóneas mexicanas, una sinopsis florística. 1. Lista de referencia. Parte I. Consejo Nacional de la Flora de México, A.C.- Universidad Autónoma Metropolitana Iztapalapa. México, D.F. 92 pp.
- García-Mendoza, A. 1995. Riqueza y endemismos de la familia Agavaceae en México. In: Linares, E., P. Dávila, F. Chiang, R. Bye y T. Elias (comps.). Conservación de plantas en peligro de extinción: diferentes enfoques. Universidad Nacional Autónoma de México. México, D.F. pp. 51-75.
- García-Mendoza, A. 2002. Distribution of the genus Agave (Agavaceae) and its endemic species in Mexico. Cact. Succ. J. 74: 177-187.
- García-Mendoza, A. 2003. Distribución del género Agave (Agavaceae) en México. Amaranto 16(2): 2-11.
- Gaut, B. S., M. Le Thierry d’Ennequin, A. S. Peek y M. C. Sawkins. 2000. Maize as a model for the evolution of plant nuclear genomes. Proc. Natl. Acad. Sci. 97: 7008- 7015.
- Gentry, H. S. 1982. Agaves of continental North America. The University of Arizona Press. Tucson. 670 pp.
- González, A. 2008. Agave victoriae-reginae. Cactus & Co. 12(3): 133-150. González Elizondo, M., M. S. González Elizondo y Y. Herrera Arrieta. 1991. Listados florísticos de México. IX. Flora de Durango. Universidad Nacional Autónoma de México. México, D.F. 167 pp.
- González Elizondo, M., R. Galván Villanueva, I. L. López Enriquez, L. Reséndiz Rojas y M. S. González Elizondo. 2009. Agaves-magueyes, lechuguillas y noas-del Estado de Durango y sus alrededores. Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional-Unidad Durango, Instituto Politécnico Nacional-Comisión Nacional para el Conocimiento y Uso de la Biodiversidad. Durango, Dgo. 163 pp.
- González-Elizondo et al.: El complejo Agave victoriae-reginae (Agavaceae) - Good-Ávila, S. V., V. Souza, B. S. Gaut y L. Eguiarte. 2006. Timing and rate of
speciation in Agave (Agavaceae). Proc. National Acad. Sci. 103: 9124-9129. - Grant, V. 1971. Plant speciation. Columbia University Press. New York. 435 pp. - Haig, S. M., E. A. Beever, S. M. Chambers, H. M. Draheim, B. D. Dugger, S. Dunham, E.
Elliott-Smith, J. B. Fontaine, D. C. Kesler, B. J. Knaus, I. F. Lopes, P. Loschl, T. D. Mullins y L. M. Sheffield. 2006. Taxonomic considerations in listing subspecies under the U.S. Endangered Species. Act. Conserv. Biol. 20(6): 1584-1593. Halda, J. J. 2000. Agave victoriae-reginae subsp. swobodae. Acta Mus. Richnov. Sect. Nat.7(2): 71.
- Hörandl, E. 2010. Beyond cladistics: extending evolutionary classifications into deeper time levels. Taxon 59(2): 345-350.
- Kolendo, J. 2009. Issues of Agave nomenclature. http://www.agavepages.co.uk/articles/nomenclature.html" onclick="window.open(this.href);return false; (versión de 25 May 2009)
- Martínez-Palacios, A., L. E. Eguiarte y G. R. Furnier. 1999. Genetic diversity of the endangered endemic Agave victoriae-reginae (Agavaceae) in the Chihuahuan Desert. Amer. J. Bot. 86(8): 1093-1098.
- Navarro-Quezada, A., R. González-Chauvet, F. Molina-Freaner y L. E. Eguiarte. 2003. Genetic differentiation in the Agave deserti (Agavaceae) complex of the Sonoran desert. Heredity 90: 220-227.
- Rocha, M., S. V. Good-Ávila, F. Molina-Freaner, H. T. Arita, A. Castillo, A. García- Mendoza, A. Silva-Montellano, B. S. Gaut, V. Souza y L. E. Eguiarte. 2006. Pollination biology and adaptive radiation of Agavaceae, with special emphasis on the genus Agave. Aliso 22: 329-344.
- Trelease, W. 1920. Agave. In: Standley, P. C. (ed.). Trees and shrubs of Mexico. C Contr. U.S. Nat. Herb. 23: 107-142.
- Stebbins, G. L. 1957. Variation and evolution in plants. 3a. ed. Columbia University Press. New York. 643 pp.
- Thiede, J. 2003. Agavaceae. In: Eggli, U. (ed.) Illustrated handbook of succulent plants. Monocotyledons. Springer. Nueva York. 400 pp. http://books.google.com.mx/books?id=1bj ... g=PA71&dq=" onclick="window.open(this.href);return false;%2 2victoriae-reginae+var.+compacta%22&source=bl&ots=lXcTp2m2iS&sig=Nmn2kot-M3 DhrL7k0CA9yCygNao&hl=es&ei=h4YaTPviA4mENNCK4cAF&sa=X&oi=book_result&ct= result&resnum=2&ved=0CBoQ6AEwAQ#v=onepage&q=%22victoriae- reginae%20var.%20compacta%22&f=false [consultado 10 Junio 2010].
- Ullrich, B. 1991a. Agave victoriae-reginae T. Moore. Kakt. and Sukk. kaartei heft 7. - Ullrich, B. 1991b. Zum Verbreitungsgebiet von Agave victoriae-reginae T. Moore. Kakt.
and Sukk. 42(11): 262-263. - Valverde, P. L., F. Vite y J. A. Zavala-Hurtado. 1996. A morphometric analysis of a
putative hybrid between A. marmorata Roezl and Agave kerchovei Lem.: Agave
peacockii Croucher. Bot. J. Linn. Soc. 122: 155-161. - Verduzco-Martínez, J., C. I. Predo-Rojas y R. Mercado-Hernández. 2009. Caracterización
e identificación taxonómica del maguey. Memorias del VII Simposium-Taller Producción y Aprovechamiento del Nopal en el Noreste de México. Revista Salud Pública y Nutrición 2: 75-90.
- Villarreal-Quintanilla, J. A. 2001. Flora de Coahuila. Listados florísticos de México XXIII. Instituto de Biología. Universidad Nacional Autónoma de México. México, D.F. 138 pp.
- Villarreal-Quintanilla, J. A. y J. A. Encina-Domínguez. 2005. Plantas vasculares endémicas de Coahuila y algunas áreas adyacentes, México. Acta Bot. Mex. 70: 1-46.
- Villaseñor, J. L., E. Ortiz y R. Redonda-Martínez. 2008. Catálogo de autores de plantas vasculares de México. Instituto de Biología, Universidad Nacional Autónoma de México, Comisión Nacional para el Conocimiento y Uso de la Biodiversidad. México, D.F. 40 pp.
Received in July 2010. Accepted in February 2011.
Translated from Spanish to English in October 2014 by Mike Papay, MS, greatly aided by Google Translate http://www.google.com/" onclick="window.open(this.href);return false;

[MJP]

Below I present five Agave victoriae-reginae sister seedlings - with the caveat that the seed source (wild - or garden) is unknown. Never the less, variation in leaf characteristics is evident in nearly every regard.

Over-all plant size varies - with the tallest specimen in the background. It is also surculose.

The spination at the leaf tips varies from just one spine in some plants, to multiple spines in others, apparently without regard to leaf-shape.