Mammillaria monochrysacantha Gonz., 2023

González-Zamora, Pedro, Aquino, David, Rodríguez, Aarón & Sánchez, Daniel, 2023, Mammillaria monochrysacantha (Cactaceae), a new endemic species from Guanajuato, Mexico, Phytotaxa 618 (3), pp. 243-253 : 244-251

Mammillaria monochrysacantha Gonz. -Zam., D.Aquino & Dan.Sánchez sp. nov. ( Figs. 1–2 ).

Type: — MEXICO. Guanajuato: Mpio. San Luis de la Paz, Sierra Gorda, 1400 m elev., 27 June 2022, P . González-Zamora et al. 84 (holotype IBUG [217112], isotype IEB) .

Diagnosis ( Table 1 , Fig. 3 ): — Mammillaria monochrysacantha differs from M. bocasana and M. crinita by the presence of one single hooked golden yellow central spine and seeds lacking arilloid, while M. bocasana and M. crinita have usually more than 1 central spine (up to 4) and seeds with arilloid. Otherwise, M. monochrysacantha contrasts from M. scheinvariana by having one persistent hooked golden yellow central spine and 28–32 radial spines ( M. scheinvariana has one thin deciduous straight red central spine and 20–24 radial spines). Likewise, M. schwarzii presents> 5 persistent straight red central spines and 33–44 radial spines.

Description: —Plants simple to branched; ordinary slender roots; stems 2.5–4.0(–6.0) cm tall, 2–5 cm in diam., growth form globose to shortly cylindrical; cortex watery; tubercles cylindrical, 5 mm long, 2 mm in diam., axils provided with tortuous bristles; areoles circular, ca. 1 mm wide; central spines 1, 3–5 mm long, golden yellow, hooked, persistent, glabrescent; radial spines 28 to 32, 4–6 mm long, white, tortuous hair-like, glabrous. Flowers infundibuliform, 11–13 mm long, 9–12 mm in diam.; outer tepals lanceolate, margin entire, pale yellow with brownish middle stripe; inner tepals lanceolate, margin entire, pale yellow with a lighter middle stripe; filaments pale yellow; anthers yellow; style pale yellow; stigma pale yellow, 4-lobed. Fruit red, claviform, 14–16 mm long. Seeds black, ca. 1 mm (diameter), arilloid absent, testa pitted.

Etymology: —The specific epithet refers to the presence of one single hooked golden yellow central spine per areole.

Distribution and habitat: — Mammillaria monochrysacantha is endemic to the Sierra Gorda in northeastern Guanajuato, Mexico. It inhabits the tropical deciduous forest ( Rzedowski 1978) on volcanic rocks, facing south at 1400 m elev. Common elements of the vegetation are Agave xylonacantha Salm-Dyck (1859: 92) , Isolatocereus dumortieri ( Scheidweiler 1837: 220) Backeberg (1941: 47) , Jatropha dioica Sessé (1794: 4 , adnot.), Myrtillocactus geometrizans (Martius ex Pfeiffer 1837: 90) Console (1897: 10) , Prosopis glandulosa Torrey (1827: 192) , Stenocactus pentacanthus A. Berger (1929: 247) , and Stenocereus huastecorum Alvarado-Sizzo, Arreola-Nava & Terrazas (2018: 13) .

Conservation status: — Mammillaria monochrysacantha is known from one locality. We estimated that the population is composed of 220 adults and 80 juvenile plants, occupying an area of about 0.040 km 2. Following the categories and criteria of IUCN Red (IUCN 2019), we proposed M. monochrysacantha as critically endangered (CE), based on the EOO, 0.009 km 2 (criterion B1) and AOO of 0.040 km 2 (criterion B2). In addition, it is only known for one locality [condition (a)], and the population size is estimated to number fewer than 250 mature individuals (criterion C1).

Taxonomic notes: — Mammillaria monochrysacantha morphologically belongs to M. ser. Stylothelae . Additionally, M. monochrysacantha flowers from spring to summer and inhabits igneous rocks as most members of the series ( Hernández & Gómez-Hinostrosa 2015). Species delimitation has been complicated due to misunderstanding of morphological variation ( Fitz-Maurice & Fitz-Maurice 2009, Hunt 2008). Recently, statistical analyses of the morphological variation in species complex of M. ser. Stylothelae allowed to delimitate and postulate new species ( González-Zamora et al. 2022; Ortiz-Brunel et al. 2023). Our study presents a robust comparison of quantitative and qualitative characters that allow us to conclude that character combination of plants with non-tuberous roots, one single golden yellow hooked central spine, several white tortuous hair-like radial spines, and non-arilloid seeds defines M. monochrysacantha as a new species in M. ser. Stylothelae . Characters related to spine morphology are distinctive even in juvenile stages ( Fig. 3 ).

Regarding the comparative species, M. crinita has been recognized as a polymorphic taxon by Fitz-Maurice & Fitz-Maurice (2009). Authors such as Hunt (2008) and González-Zamora et al. (2022) mentioned that morphological variation is greater between populations rather than inside populations and claim a narrow concept of M. crinita . Although morphotypes of M. crinita can include plants with tortuous hair-like radial spines (e.g., Fitz-Maurice & Fitz-Maurice 2182, MEXU), none of them comprises plants with only one central spine at maturity ( Fitz-Maurice & Fitz-Maurice 2009) as observed in M. monochrysacantha . According to González-Zamora et al. (2022), observed populations and reviewed synonyms of M. crinita suggest the presence of pubescent radial spines and seeds with arilloid; those characters are absent in the proposed new species. M. crinita inhabits floors of igneous rocks in xerophytic scrub and oak forest. The closest population is found ca. 10 km away from M. monochrysacantha , at 1900 m a.s.l., in oak forest. This morphotype (Guzmán 3541, IEB; Naturalista 2023 [obs. 65740054]) is considered as M. brevicrinita Reppenhagen (1987: 42) , a synonym of M. crinita subsp. leucantha ( Korotkova et al. 2021) , and it presents 3–4 pubescent central spines and pubescent straight radial spines. Otherwise, M. bocasana exhibits more than one bicolored central spines and seeds whit arilloid ( Craig 1945, González-Zamora et al. 2022). Besides, M. bocasana inhabits floors and humus of igneous rocks in pine-oak forest in central San Luis Potosí state, and closet populations are located 114 km away from M. monochrysacantha . Likewise, M. monochrysacantha and M. scheinvariana are morphologically similar, and both inhabit on cliffs of igneous rocks in deciduous forest at the Sierra Gorda in Guanajuato and Querétaro states, respectively. Even so, M. scheinvariana is distinctive by having one thin straight deciduous central spine and less radial spines. M. scheinvariana is located 129 km away from M. monochrysacantha .

Finally, Mammillaria schwarzii could be considered as a relative due to it bears hair-like radial spines; however, radial and central spines are straight and greater in number ( Table 1 ). The population of M. schwarzii is situated in western Guanajuato; it grows on igneous cliffs in the ecotone of xerophytic scrub and oak forest, 85 km from M. monochrysacantha . Phylogenetic relationships of M. ser. Stylothelae should be completely evaluated to infer if likehair radial spines represent a homology or if this character has evolved independently in some lineages of the series.

Identificaction key of Mammillaria monochrysacantha and close species: —This key includes recognized species of Mammillaria ser. Stylothelae ( Korotkova et al. 2021) in Guanajuato, Querétaro, and San Luis Potosí states, Mexico.

- Areoles oval; central spines absent or 1(–2).......................................................................................................................................5

3. Adult stem <2.5 cm in diameter; central spines <2.5 mm long........................................................................................ M. tezontle

- Adult stem> 2.5 cm in diameter; central spines> 2.5 mm long........................................................................................................4

4 Adult stem 2.5–4 cm in diameter; roots fibrous ............................................................................................ M. crinita subsp. crinita

- Adult stem 3.6–5.2 cm in diameter; roots tuberous.................................................................................. M. crinita subsp. leucantha

5. Radial spines strongly pubescent, feather-like; central spine thick....................................................................................... M. duwei

- Radial spines pubescent; central spine thin ............................................................................................................................ M. nana

6. Radial spines straight..........................................................................................................................................................................7

- Radial spines tortuous hair-like ........................................................................................................................................................12

7. Central spines ≤ 4 ...............................................................................................................................................................................8

- Central spines> 4 .............................................................................................................................................................................10

8. Radial spines 10–15; seed without arilloid.........................................................................................................................................9

- Radial spines <10; seed with arilloid............................................................................................................................. M. mathildae

9. Radial spines glabrous; flower magenta; on limestone soil .................................................................................... M. erythrosperma

- Radial spines slightly pubescent, flower white to cream; on igneous soil ......................................................................... M. painteri

10. Central spines> 10; flower magenta ........................................................................................................................ M. rzedowskiana

- Central spines <10; flower white to cream......................................................................................................................................11

11. Central spines (3–)4–6(–8); radial spines <32.......................................................................................................... M. morentiniana

- Central spines (5–)6–8(–9); radial spines> 32................................................................................................................ M. schwarzii

12. Central spines 2–4(6); seed with arilloid......................................................................................................................... M. bocasana

- Central spine 1; seed without arilloid...............................................................................................................................................13

13. Central spine straight, deciduous, brown; radial spines 20–24 ................................................................................ M. scheinvariana

- Central spine hooked, persistent, golden yellow; radial spines 28–32............................................................. M. monochrysacantha

Additional specimens examined: — Mammillaria monochrysacantha . MEXICO. Guanajuato: Mpio. San Luis de la Paz , Sierra Gorda, 1400 m elev., 23 January 2023, González-Zamora 119 ( IBUG [217973]) .

Mammillaria bocasana . MEXICO. San Luis Potosí: Mpio. Ahualulco, N of Ahualulco toward Moctezuma , 17 July 1989, Fitz-Maurice & Fitz-Maurice 1928 ( MEXU) ; Puente Tecolote , 27 November 1989, Fitz-Maurice & Fitz-Maurice 1965 ( MEXU) ; near Tulillo , 6 October 1989, Fitz-Maurice & Fitz-Maurice 1970 ( MEXU, DES) ; S of La Aduana , 23 November 1993, Fitz-Maurice & Fitz-Maurice 2274 ( MEXU) . Mpio. Charcas, south of Charcas , 13 August 1991, Fitz-Maurice & Fitz-Maurice 2151 ( DES) . Mpio. Cerro San Pedro , SE of San Pedro, 9 October 1989, Fitz-Maurice & Fitz-Maurice 1973 ( MEXU) . Mpio. Mexquitic de Carmona , NE of Valle Umbroso, 8 November 1989, Fitz Maurice & Fitz-Maurice 1946 ( MEXU, DES) ; SW of Mexquitic , 12 November 1989, Fitz-Maurice & Fitz-Maurice 1954 ( MEXU, DES) ; Mexquitic de Carmona , 5 July 2020, González-Zamora 13 ( IBUG) . Mpio. Moctezuma, km 54 to Charcas , 13 August 1991, Fitz-Maurice & Fitz-Maurice 2154 ( DES) . Mpio . San Luis Potosí, 1.2 km de Valle Umbroso , hacia el N, 26 April 2010, Arias et al. 2042 ( MEXU) ; E of Mantiquillas , 7 April 1990, Fitz-Maurice & Fitz-Maurice 1996 A ( MEXU, DES) ; SE of Bocas , 25 November 1993, Fitz-Maurice & Fitz-Maurice 2276 ( MEXU) . Mpio. Villa Hidalgo. SW of Derramaderos , 12 May 1984, Fitz-Maurice & Fitz-Maurice 1520 ( MEXU) ; Los Ojitos, al N de la ciudad de San Luis Potosí, 6 April 1990, Fitz-Maurice & Fitz-Maurice 1996 ( MEXU, DES) .

Mammillaria crinita subsp. crinita . MEXICO. Hidalgo: Mpio. Actopan , SW of Actopan, 26 August 2000, Fitz-Maurice & Fitz-Maurice 2423 (MEXU) . Mpio. Ixmiquilpan , SW of Ixmiquilpan, 8 December 1993, Fitz-Maurice & Fitz-Maurice 2298° ( MEXU) ; al S de Panales , 17 November 2021, González-Zamora 24 ( IBUG) . Mpio. Zimapán, S shore of Presa Zimapán , 28 March 1995, Fitz-Maurice & Fitz-Maurice 2372 ( MEXU) ; E shore of Presa Zimapán , 17 July 1995, Fitz-Maurice & Fitz-Maurice 2379 ( MEXU) ; Botha , 21 November 2021, González-Zamora 25 ( IBUG) ; Mpio. Tecozautla, near Nueva Aljibe , 25 October 1997, Fitz-Maurice & Fitz-Maurice 2401 ( MEXU) . Guanajuato: Mpio. Atarjea, aproximadamente 5 a 6 km sobre la terracería Aldama-Atarjea , 19 June 2014, Arias & Aquino 2225 ( MEXU) . Mpio. San Luis de la Paz , E of San Luis de la Paz, 17 March 1987, Fitz-Maurice & Fitz-Maurice 1641 ( MEXU) ; carretera MEX 57, 10 April 2021, González-Zamora 20 ( IBUG) ; ca. 2 km al N de Puerto de Palmas sobre camino a Álamos de Martínez , 17 March 1995, Bárcenas & al. 817 ( MEXU) . Mpio. Xichú, 9 km de Xichú, por la brecha a Atarjea , 30 May 1996, Pérez-Calix & S. Zamudio 3340- A ( IEB) . Querétaro: Mpio. Colón , N of Colón, 18 October 1991, Fitz-Maurice & Fitz-Maurice 2182 ( MEXU) ; alrededores de presa Colón , 29 May 2021, González-Zamora 23 ( IBUG) ; Panales , 19 November 1986, Guzmán 685 ( ANSM) ; 2.6 km al OSO de San Martín , 20 May 2014, Rubio 876 ( IEB) . Mpio. Peñamiller, near Molinitos , 21 December 1994, Fitz-Maurice & Fitz-Maurice 2384 ( MEXU) . Mpio. Tolimán, este de Tolimán , 3 September 2022, Aquino & González-Zamora 540 ( MEXU) ; km 48, S of Tolimán , 1 March 1992, Fitz-Maurice & Fitz-Maurice 2187 ( MEXU) ; km 49.3 de la carretera Bernal-Tolimán , 25 April 2013, Rubio 523 ( QMEX) ; San Pablo Toliman-Higuerillas , 8 February 2002, Sánchez 122 ( MEXU) ; laderas de rocas ígneas cercanas a Tolimán , 27 November 1973, Sánchez-Mejorada 2193 ( MEXU) ; Tolimán, La Vereda , 27 April 2021, González-Zamora 22 ( IBUG) .

Mammillaria crinita subsp. leucantha . MEXICO. Guanajuato: Mpio. San Luis de la Paz: Río El Aguacate , al SO de El Realito, 29 February 2012, Guzmán 3541 (IEB) . Mpio. Victoria. 1 km al N de El Tepehuaje, c. 72 km de Cañada de Moreno sobre la terracería a Mineral El Refugio ; la desv. [desviación] a Mineral el Refugio está a 28 km de Cañada de Moreno sobre la terracería a Xichú , 11 March 1995, Bárcenas & Gómez-Hinostrosa 481 ( MEXU) ; south of Álamos , 19 March 1996, Fitz-Maurice & Fitz-Maurice 2390 ( MEXU) . San Luis Potosí: Mpio. Ahualulco, Cerro El Picacho , 6 September 1989, Fitz-Maurice & Fitz-Maurice 1941 ( MEXU) . Mpio. Armadillo de los Infantes, near Flor de Calabaza , 11 September 1986, Fitz-Maurice & Fitz-Maurice 1602 ( MEXU) . Mpio. Charcas, Rancho los Álamos , 6 December 2019, González-Zamora 12 ( IBUG) . Mpio. Cerritos, c. 35 km al N de Río Verde sobre carretera a Cerritos , 4 November 1997, Bárcenas 1501 ( MEXU) . Mpio. Guadalcázar, 3 km al N de la carretera San Luís Potosí – Entronque Huizache en dirección a El Peyote , 1 May 2005, Goettsch 687 ( MEXU) . Mpio. Villa Hidalgo, W of Peotillos, 12 October 1986, Fitz-Maurice & Fitz-Maurice 1603° ( MEXU) . Mpio. Villa de Guadalupe, Leoncito , N of Hacienda Solís, 14 September 1986, Fitz-Maurice & Fitz-Maurice 1603 ( DES) . Mpio. Zaragoza , N of Zaragoza, 29 October 1986, Fitz-Maurice & Fitz-Maurice 1605 ( MEXU) .

Mammillaria scheinvariana . MEXICO. Querétaro: Mpio. Cadereyta de Montes, Presa de Zimapán, 9 September 1997, Equipo de Rescate Zimapán s.n. ( IEB) ; north shore of Presa Zimapán , 17 July 1998, Fitz-Maurice & Fitz-Maurice 2378 ( MEXU) ; Mesa de León, E de La Vega , 1650 m, 13 September 2021, Sánchez & Martínez 884 ( IBUG) .

Mammillaria schwarzii . MEXICO. Guanajuato: Mpio. San Felipe, Southeast of El Cubo , 3 October 1987, Fitz-Maurice & Fitz-Maurice 1687 B ( MEXU) ; 29 November 2021, González-Zamora 27 ( IBUG) .

Figures

FIGURE 1. Mammillaria monochrysacantha sp. nov.A) Plant in habit showing the typical globose growth form.B) Stem and root system. C) Turgid stem during rainy season showing evident cylindrical tubercles. D) Dehydrated stem during dry season, tubercles are not evident do to they are covered by the hair-like radials stem. E) Plants growing on igneous rocks. F) Flower morphology. D) Fruit shape. E) Seed morphology.

FIGURE 2. Mammillaria monochrysacantha. A) Stem with globose growth form.B) Areole showing central and radial spines. C) Flower. D) Fruit. E) Seed.

FIGURE 3. Morphological comparison of some Mammillaria species with hair-like radial spines in M. ser Stylothelae. Mammillaria bocasana (first row: A–D). Mammillaria crinita (second row: E–H). Mammillaria monochrysacantha (third row: I–L). Mammillaria scheinvariana (fourth row: M–P). Mammillaria schwarzii (fifth row: Q–T). Comparison of growth form of the stem (first column); areole, central and radial spines (second column); close-up of plantlets (third column); and flower morphology (fourth column).