New Euphorbiaceae from Mexico

Victor Steinmann

doi:10.5642/aliso.20001902.05

Abstract

This article contained descriptions of five new taxa of Mexican Euphorbiaceae. Euphorbia (subg. Agaloma) nayarensis is endemic to pine-oak woodland in the mountains of central Nayarit. It appears related to E. soobyi but differs by possessing linear to linear-ovate leaves. Croton varelae is also endemic to central Nayarit. A key was provided to distinguish this species, a member of sect. Geiseleria, from the seven other Mexican species of this section. Croton ramillatus var. magniglandulifer occurs in the states of Guerrero and Morelos. This new variety differs from var. ramillatus by the possession of larger petiolar glands. Croton michaelii occurs in Aguascalientes and Durango. It is uncertain to which section of Croton this species belongs. It resembles Croton yecorensis but is distinguished by possessing a lepidote indumentum and by lacking conspicuous stipitate glands. Croton disjunctus has been collected in Chihuahua and Aguascalientes, at localities separated by more than 600 km. This species appears to be most closely akin to Croton fruticulosus Torr., from which it is separated by glabrous, evident (vs. pubescent, nearly obsolete) stipules and multifid (vs. bifid) styles.

Highlights

The Euphorbiaceae are one of the largest and most diverse Angiosperm families in Mexico
It appears related to E. so ob yi but differs by possessing linear to linear-ovate leaves
Croton varelae is endemic to central Nayarit

Summary

INTRODUCTION

The Euphorbiaceae are one of the largest and most diverse Angiosperm families in Mexico. 25 staminate flowers distally; bracts subulate, 0.7-1.1 mm long , each side of the base subtended by a group of 2-5 glands similar to those of the stipules; staminate flowers on pedicels 1.3-3.1 mm long, calyx lobes 5, united towards the base, their free lobes deltoid, acute, 0 .9-1.1 mm long, the petals 5, white , narrowly oval to oblong, 1.2-1.7 mm long, the receptacle densely villous, the stamens II, filaments glabrous, 0.6-1.7 mm long, anthers elliptic, 0.4-0.6 mm long, basifixed; pistillate flowers subsessile or on stout pedicels to 0.5 mm long, calyx lobes 5-6, adaxial lobes reduced, subulate to narrowly triangular, acute, 0.8-2.1 mm long, abaxial lobes well developed, linear to obovate to spathulate, 2.6-6.7 mm long, subacute to rounded at the apex, petals absent, the ovary nearly globose, very shallowly 3-lobed, stellate-hispid, the longer rays of the trichomes to 1.5 mm long, the styles 3, united at the base, bipartite, the divisions filiform, rust brown, minutely papillate, 1.32.2 mm long, sometimes bearing scattered stellate trichomes; capsules 3.2-4.1 mm in diameter; seeds elliptic to oblong, 2.7-3.4 mm long, 2.0-2.3 mm wide, dorso-ventrally compressed, shallowly foveolate, shiny, mottled black-gray, with a fleshy, cream-yellow, reniform caruncle 0.3-0.7 mm long, 1.2-1.5 mm wide. I km north of Mesa del Nayar along the trail to EI Congrejo and just before Arroyo EI Canaveral, 104°38'45"N, 22°13 '45"W, 1300 m, 14 Oct 1996, Steinmann 1063 (holotype RSA; isotypes ARIZ, BM, DAY, FCME, IBUG, NY)

H 1 em

Ovaries and abaxial leaf surfaces lepidote