Euphorbia zamudioi V.W. Steinm. & P. Carrillo, 2018

Steinmann, Victor W. & Carrillo-Reyes, Pablo, 2018, A revision of the New World Euphorbia adiantoides complex (Euphorbiaceae), Phytotaxa 350 (3), pp. 201-222 : 217-219

Euphorbia zamudioi V.W. Steinm. & P. Carrillo , sp. nov. ( Fig. 6 )

Similar to Euphorbia multiseta but differs by having primary stems from slender spreading rhizomes that sometimes form elongated tuberous thickenings, glabrous involucres, smaller leaves, and dichasial bracts with shorter stipules.

Type:— MEXICO. Querétaro: municipio de Landa de Matamoros, 7.5 km al E de La Vuelta, por la carr. a El Lobo , 21°16’14”N, 99°12’21”W, 1600 m, 5 September 2009, S. Zamudio & C.A. Ramírez-Sosa 14520 (holotype MEXU!; isotypes ARIZ!, RSA!) .

Perennial herb to 35(–50) cm tall, from slender spreading rhizomes, these sometimes forming intervals of elongated tuberous thickenings. Stems erect, terete or weakly angled, glabrous, internodes 0.5–3.5(–7) cm long. Leaves alternate; stipules subulate, 0.2–0.5 mm long, at each side of the base of the petiole; petiole about as long as the blades, slender, 0.8–2.2 cm long, sometimes subpeltately attached, glabrous or rarely with a few scattered trichomes; blade ovate to nearly orbicular, 1.1–2(–2.5) × 8–1.8(–2) cm, base rounded to truncate; apex obtuse, sometimes mucronulate with a mucro to 0.6 mm long, margin entire occasionally somewhat revolute, upper surface mostly glabrous or with isolated trichomes, lower surface glabrous to sparsely pubescent, penninerved with a prominent midvein, membranaceous to subcoriaceous. Cyathia in weakly defined, open axillary dichasia 1–7 cm long, rachis papilose, sparsely pilose; dichasial bracts opposite, stipules filiform, 0.2–0.7(–0.9) mm long, blade ovate, broadly ovate or orbicular, rarely almost transversely reniform, 0.3–0.5 × 0.4–0.6 cm, with a cuspidate to caudate tip 0.4–1.3 mm long, pilose to loosely sericeous; peduncle 0.5–2.7 mm long, papilose, glabrous or with a few scattered trichomes. Involucre campanulate, 0.8–1.0 × 0.9–1.1 mm, glabrous; glands (4–)5, transversely oblong to transversely reniform, 0.2–0.25 × 0.3–0.6 mm; appendages divided into 4–6 filiform segments, 0.3–0.7 × 0.05 mm, glabrous; lobes triangular to ovate, 0.2 mm long, laciniate. Staminate flowers 15–20. Ovary globose to slightly 3-lobed, glabrous to pilose; styles 3, free to the base, entire, 0.4–0.6 mm long, cylidrical, glabrous, stigmas capitate. Capsule on a glabrous gynophore exserted by 2.2–3.9 mm, oblate, 3-lobed, 2.3–2.8 × 3.2–3.4 mm, glabrous to pilose; columella 1.3–1.8 mm. Seeds ovoid, rounded in cross-section, 1.5–1.9 × 1.2–1.4 mm, dark-brown to blackish, apex rounded, base rounded to truncate, with longitudinal rows of isodiametric depressions the bottow having a punctiform pit and bordered by low, conical, non-translucent tubercles; ecarunculate.

Distribution, habitat, and phenology: — Euphorbia zamudioi is endemic to the Sierra Madre Oriental of eastern Mexico and known with certainty from the states of Querétaro, Hidalgo, and Tamaulipas where it is found at elevations from 1100 to 2450 m ( Fig. 4 ). Given the close proximity of some collections to the state of San Luis Potosí, we expect that this species also occurs there. It inhabits a number of types of vegetation including oak woodlands, juniper woodlands, pine-oak forest, cloud forest and submontane scrub. It often grows on rocky limestone substrates. Flowering and fruiting broadly overlap, and reproductive plants have been collected from April to November.

Conservation status: — Euphorbia zamudioi is known from 26 localities in northern and central Mexico, and some of these localities are located in the Natural Protected Area of the Sierra Gorda Biosphere Reserve ( CONANP 2018). Although it apparently has no conservation concerns at present, its conservation status was evaluated according to the criteria and categories of the IUCN (2001, 2014). The Extent of Occurrence (EOO) is 20,310 km 2, and the Area of Occupancy (AOO based on 2 km 2 grids) is 100 km 2. Thus, a preliminary category of Near Treatened (NT) is proposed.

Etymology: — It is our pleasure to name this species in honor of Sergio Zamudio Ruiz, expert on the family Lentibulariaceae and the flora of Mexico, in particular the region of the Bajío. During the past 20 years he has made numerous collections of this taxon, including the type, and he assisted us with fieldwork and observations on living plants.

Morphology and phylogenetic relationships: — Euphorbia zamudioi is closely related to and potentially derived from within E. breedlovei . In addition to having allopatric distributions, they can be separated morphologically. Euphorbia zamudioi is a rhizomatous perennial herb that often has tuberous underground storage structures, whereas E. breedlovei is an annual from a slender taproot. Furthermore, the seeds of E. zamudioi tend to be larger (1.5–1.9 mm long vs. 0.9–1.2(–1.4) mm long).

Additional specimens examined (paratypes): — MEXICO. Hidalgo: mpio. Jacala de Ledezma , without further information, 25 June 1939, V.H. Chase 7134 ( MICH, MO) ; mpio. Jacala de Ledezma, km 219 de la carretera México – Nuevo Laredo, entre Zimapán y Jacala , Cruz 1416 ( ENCB) ; mpio. Cardonal, Barranca de Tolantongo, 13.6 km al E de El Cubo por el camino a las Grutas de Tolantongo , 20°38’10”N, 98°59’25”W, 1730 m, 17 October 2005, P. Carrillo-Reyes & E. Ruiz 4838 ( IBUG) ; mpio. Zimapán, 5 air km SSW of Jacala on MEX 85 on the SW shoulder of Cerro Hoya La Zarca , road changes orientation from E–W to NW–SE at the site, also 5 air km N of Durango, 20°57’15”N, 99°13’20”W, 1800 m, 13 July 1991, M. Mayfield et al. 838 ( TEX) ; mpio. de Jacala de Ledezma , 3 km al W de Jacala, [21°00’21”N, 99°13’39”W], 1500 m, 15 September 1966, J. Rzedowski 23100 ( MICH) ; mpio. Jacala de Ledezma, 32 mi NE of Zimapan, [20°58’07”N, 99°13’17”W], 21 August 1957, U.T. Waterfall 14171 ( MICH). Querétaro: mpio. Landa de Matamoros, 2–3 km al SW de El Madroño , [21°16’N, 99°08’W], 1900 m, 23 May 1990, E. Carranza 2494 ( IEB) ; mpio. Landa de Matamoros, 7 km por la brecha a Tres Lagunas y Valle de Guadalupe, [21°18’11”N, 99°10’47”W], 2000 m, 2 July 1987, H. Díaz Barriga 3813 ( IEB) ; mpio. Landa de Matamoros, Hoyo del Lobo , ± 5 km al N de Acatitlán de Zaragoza, [21°15’05”N, 99°11’07”W], 1780 m, 2 October 1989, E. González P. 1086 ( IEB, MEXU) ; mpio. Jalpan de Serra, Cerro de la Joya, camino a Las Lagunitas , [21°28’20”N, 99°13’32”W], 1350 m, 5 September 1989, C. Guzmán 134 ( IEB, MEXU) ; mpio. Landa de Matamoros, 6–7 km al NE de la Lagunita de San Diego, vertiente SE del Cerro Grande , [21°23’42”N, 99°08’26”W], 2300 m, 2 August 2000, G. Ocampo & E. Pérez 889 ( IEB) ; mpio. Landa de Matamoros, por el camino al Puerto de La Ciénega, cerca de La Lagunita de San Diego , [21°23’15”N, 99°08’44”W], 2100 m, 13 June 2001, G. Ocampo & E. Pérez C. 1027 ( IEB) ; mpio. Landa de Matamoros , 8 km al W de Lobo, [21°15’22”N, 99°11’10”W], J. Rzedowski 9305 ( ENCB) ; mpio. Landa de Matamoros, 10 km al NW de El Madroño, sobre el camino a Tres Lagunas , [21°18’25”N, 99°11’11”W], 1800 m, 1 August 1987, J. Rzedowski 44089 ( IEB) ; mpio. Landa de Matamoros , cerca de Tres Lagunas, [21°18’55”N, 99°11’37”W], 1700 m, 22 April 1988, J. Rzedowski 46682 ( IEB) ; mpio. Landa de Matamoros , 1 km al S de El Pinalito, [21°18’09”N, 99°10’40”W], 2000 m, 18 September 1997, J. Rzedowski 53477 ( MEXU) ; mpio. Landa de Matamoros, 8 km al NW de Madroño, sobre el camino a Laguna de Guadalupe, [21°18’N, 99°11’W], 1800 m, 18 September 1997, J. Rzedowski 53503 ( IEB, MEXU, MICH) ; mpio. Landa de Matamoros , 5–6 km al N de La Parada, El Naranjo, [21°32’15”N, 99°10’32”W], 1400 m, 24 July 1991, B. Servín, 1203 ( IEB) ; mpio. Landa de Matamoros, La Mesa, ca. 1.5 km from La Lagunita de San Diego along the trail to Llano Chiquito ; 21°22’58”N, 99°08’32”W, 2100 m, 11 June 2002, V.W. Steinmann et al. 2501 ( RSA) ; mpio. Landa de Matamoros, sobre MEX 120, 7.2 km al O del camino a Valle de Guadalupe, 21°16’24.8”N, 99°12’21.3”W, V.W. Steinmann et al. 5833 ( IEB) ; mpio. Amealco , 1 km al NE de San Miguel Deheti, [20°12’59”N, 100°06’25”W], 2450 m, 7 September 1987, S. Zamudio 5864 ( IEB, MEXU) ; mpio. Jalpan de Serra , 9 km al S de La Parada, [21°26’10”N, 99°14’23”W], 1400 m, 23 June 2988, S. Zamudio & E. Carranza 6528 ( IEB) ; mpio. Jalpan de Serra, El Ojo de Agua, San Juan de Los Durán , 21°27’41”N, 99°10’42”W, 1300 m, 24 October 2003, S. Zamudio & L. Hernández 12554 ( IEB) ; mpio. Jalpan de Serra, El Cerro El Pilón, ± 3 km al S de La Parada, [21°29’45”N, 99°10’24”W], 1100 m, 13 September 1997, S. Zamudio et al. 10513 ( IEB). Tamaulipas: mpio. Gómez Farías, 3 km en línea recta al NNO de Julilo, 4.5 km sobre el camino a La Joya Veinte de Abril ( Joya de Salas ), 23°10’00.5”N, 99°13’24.1”W, 1710 m, 23 October 2009, P. Carrillo-Reyes & E.M. Piedra 5633 ( IBUG) ; mpio. Juamave, 4.9 km en línea recta al NNO de Julilo, 5.8 km sobre el camino a La Joya Veinte de Abril ( Joya de Salas ), 23°11’12.4”N, 99°15’05.5”W, 1965 m, 23 October 2009, P. Carrillo-Reyes & E.M. Piedra 5641 ( IBUG) ; mpio. Juamave, 3.5 km al ENE de La Joya Veinte de Abril (Joya de Salas) por el camino a Julilo (ca. 3.2 km en línea recta), 23°10’52.3”N, 99°16’06.6”W, 1775 m, 23 October 2009, P. Carrillo-Reyes & E.M. Piedra 5651 ( IBUG) ; mpio. Juamave, 5.5 km (en línea recta) al NNO de la Joya de Molina por el camino a Juamave , 23°15’01”N, 99°22’04”W, 1730 m, 23 October 2009, P. Carrillo-Reyes & E.M. Piedra 5678 ( IBUG) ; mpio. Gómez Farías, region of Sierra de Guatemala, at and just W of Tierra Colorado , about 3 km N of Julilo, 23°5–7’N, 99°14’W, 1600 m, 19–25 August 1984, M.C. Johnston 12835 ( TEX) ; mpio. Gómez Farías Gómez Farías region, between Rancho del Cielo and Charco de los Perros , [23°05’N, 99°11’W], 4000–6000 ft, spring 1965, M.B. Webster 144 ( TEX) .

Figures

FIGURE 4. Geographic distribution of species of the Euphorbia adiantoides complex.

FIGURE 6. Euphorbia zamudioi. a. Habit; b. node with stipules; c. dichasial bracts and cyathia; d. cyathium, side view; e. dissected cyathium with female flower removed; f. seed, dorsal view; g. seed, ventral view; h. seed, apical view. All from Steinmann et al. 5833. Drawn by Manuel Escamilla.