A TAXONOMIC REVISION OF TAXA IN STYRAX SERIES CYRTA (STYRACACEAE) WITH VALVATE COROLLAS Gary Li Peter W. Fritsch Department of Botany Botanical Research Institute of Texas California Academy of Sciences 1700 University Drive 55 Music Concourse Drive Fort Worth, Texas 76107, U.S.A. San Francisco, California 94118, U.S.A. [email protected] Department of Biology, San Francisco State University 1600 Holloway Avenue, San Francisco, California 94132, U.S.A. ABSTRACT Several taxonomic treatments of Styrax (Styracaceae) exist in regional floras of Asia, but the Asian species of the genus have not been com- prehensively revised since 1907. A treatment of the Asian taxa of S. series Cyrta with imbricate floral aestivation was accomplished in 2003. To complete the taxonomic revision of S. series Cyrta, we conducted a taxonomic revision of the species of the series with valvate aestivation of the corolla lobes. Our revision comprises 11 species with a combined distribution from eastern India through southern China and Malesia, Melanesia, and Micronesia, although the group is absent from the Philippines. We resurrected S. bracteolatus, S. rubifolius, and S. warburgii as species to be recognized, and we corrected the misapplication of S. finlaysonianus, previously used for a species in S. series Benzoin. Styrax finlaysonianus and S. warburgii are segregated from the broader concept of S. agrestis recognized in prior treatments. The circumscriptions of the heretofore poorly delimited species S. confusus, S. faberi, and S. fortunei are clarified and their possible introgressants discussed. We observed unique combinations of characters in some problematic specimens whose taxonomic status remains unresolved because only single specimens with either flowers or fruits were available; at least some of these may represent undescribed species. Lectotypes are designated for Cyrta agrestis, S. argyi, S. bracteolatus, S. calvescens, S. casearifolius, S. confusus var. microphyllus, S. dasyanthus, S. dasyanthus var. cinerascens, S. faberi, S. finlaysonianus, S. formosanus, S. fortunei, S. fukienensis, S. henryi, S. henryi var. microcalyx, S. iopili- nus, S. philadelphoides, S. rostratus, S. rubifolius, S. serrulatus var. agrestis, and S. virgatus. A neotype is designated for S. warburgii. Keys, descriptions, distribution maps, and conservation assessments are provided for all species. Styrax agrestis, S. bracteolatus, and S. rubifolius are rare endemics of conservation concern, with highly restricted distributions. KEY WORDS: Asia, Styracaceae, Styrax, taxonomy RESUMEN Existen varios tratamientos taxonómicos de Styrax (Styracaceae) en floras regionales de Asia, pero las especies asiáticas del género no han sido revisadas en profundidad desde 1907. Se realizó un tratamiento de los taxa asiáticos de S. series Cyrta con estivación imbricada en 2003. Para completar la revisión taxonómica de S. series Cyrta, hicimos una revisión taxonómica de las especies de la serie con estivación valvar de la corola. Nuestra revisión comprende 11 especies con una distribución combinada desde el este de India hasta el sur de China Malasia, Melanesia y Micronesia, aunque el grupo está ausente de Filipinas. Recuperamos S. bracteolatus, S. rubifolius, y S. warburgii como especies reconocidas, y corregimos la mala aplicación de S. finlaysonianus, previamente usad para una especie en S. series Benzoin. Styrax finlaysonia- nus y S. warburgii son segregadas del amplio concepto de S. agrestis reconocido en tratamientos anteriores. Se clarifican las circunscripcio- nes de las hasta ahora pobremente delimitadas especies S. confusus, S. faberi, y S. fortunei y se discuten sus posibles introgresores. Observamos combinaciones únicas de caracteres en algunos especímenes problemáticos cuyo estatus taxonómico queda sin resolver porque solo estuvieron disponibles especímenes únicos en los que estaban disponibles las flores o los frutos; al menos algunos de estos pueden representar especies no descritas. Se designan lectotipos par Cyrta agrestis, S. argyi, S. bracteolatus, S. calvescens, S. casearifolius, S. confusus var. microphyllus, S. dasyanthus, S. dasyanthus var. cinerascens, S. faberi, S. finlaysonianus, S. formosanus, S. fortunei, S. fukienensis, S. henryi, S. henryi var. microcalyx, S. iopilinus, S. philadelphoides, S. rostratus, S. rubifolius, S. serrulatus var. agrestis, y S. virgatus. Se designa un neotipo para S. warburgii. Se aportan claves, descripciones, mapas de distribución, y evaluaciones de conservación para todas las especies. Styrax agrestis, S. bracteolatus, y S. rubifolius son endemismos raros de preocupación por su conservación, con distribuciones altamente restringidas. INTRODUCTION Styrax L. (Styracaceae) is a genus of about 140 species of trees and shrubs distributed in the Mediterranean region, eastern Asia (broadly considered here as encompassing South, East, and Southeast Asia through Melanesia and Micronesia), and the Americas (Fritsch 2015). This range is typical of many other genera of plants distributed among the refugia of Tertiary mixed-mesophytic forests in the Northern Hemisphere, J. Bot. Res. Inst. Texas 12(2): 579 – 641. 2018 This document is intended for digital-device reading only. Inquiries regarding distributable and open access versions may be directed to [email protected]. 580 Journal of the Botanical Research Institute of Texas 12(2) except that Styrax also has a large Neotropical component extending south to the southern Andes, northern Argentina, and Uruguay (Fritsch 1999, 2001). Styrax is the largest of the 12 genera comprising the Styracaceae. Characters that distinguish Styrax from the other genera in the family include a high (vs. low) attachment of the staminal tube on the corolla, the presence (vs. absence) of placental obturators, bitegmic (vs. unitegmic) ovules, and a thick (vs. thin) seed coat. The combination of the following characters serves to further distin- guish Styrax from other genera of the Styracaceae: absence of bud scales, presence of pseudoterminal fertile shoots, non-articulated pedicels, a short hypanthium, glossy trichomes that are circular in cross-section on the staminal filaments, a 3-carpellate ovary, presence of mesocarp, and a seed-to-carpel ratio ≤ 1 (Fritsch et al. 2001; Fritsch 2004). Like the other genera in the family, Styrax has a vestiture of stellate trichomes (sometimes modified into peltate scales or simple trichomes), generally twice the number of stamens as corolla lobes, and introrsely dehiscent anthers with a large, linear connective (Fritsch et al. 2001; Fritsch 2004). In the last worldwide monograph of the genus, Perkins (1907) divided Styrax into two sections, Styrax and Foveolaria (Ruiz & Pav.) Perkins, based on the number of ovules in the gynoecium. Styrax section Styrax was further divided into two series, Styrax and Valvatae (Gürke) Perkins, on the basis of imbricate and valvate corolla aestivation, respectively. Despite using the latter for infrageneric classification, Perkins recognized that there were certain species in S. series Valvatae with subvalvate aestivation, an apparently intermediate state between valvate and imbricate aestivation wherein the corolla lobes are contiguous but oblique in cross sec- tion. On this basis, Steenis (1932), in a revision of the Malesian species of Styrax, disregarded corolla aestiva- tion, instead combining together several different species of imbricate and subvalvate Styrax into S. serrulatus Roxb., a strictly subvalvate species in our view. Fritsch (1999) conducted a morphological phylogenetic analysis of Styrax and on this basis recircum- scribed the infrageneric classification of the genus. Styrax section Styrax (about 33 species) was recircum- scribed to include all the deciduous species. This was supported by the presence of young shoots with scattered stalked stellate trichomes distinct from the rest of the vestiture (vs. without stalked trichomes unless accompa- nied by a dense tomentum of the same type of vestiture) and membranaceous (vs. subcoriaceous) corolla lobes. Styrax section Valvatae Gürke (about 97 species) was recircumscribed to include species with valvate (vs. imbricate or subvalvate) corolla aestivation, the evergreen (vs. deciduous) condition, straight (vs. convex) sides of the corolla in bud, and concave (vs. planar) staminal filaments. Within section Styrax, S. series Styrax (three species) is supported by strictly pseudoterminal (vs. pseudoterminal and lateral) inflorescences, and S. series Cyrta (Lour.) P.W. Fritsch (about 30 species) is supported by glandular-serrate (vs. entire) laminar margins. Fritsch’s reclassification of Styrax reflected Perkins’s recognition of the difference between the truly valvate species of Styrax, all in S. section Valvatae, and the subvalvate species of Styrax, now under S. series Cyrta. A molecular phylogenetic analysis (Fritsch 2001) corroborates this infrageneric classification. The taxonomy of the species in Styrax series Cyrta had been poorly understood because a comprehensive study of specimens was lacking. Although several regional floristic treatments of Styrax in eastern Asia were produced (Steenis 1932, 1949; Croft 1981; Svengsuksa & Vidal 1992; Hwang & Grimes 1996; Li 1998), they generally did not appear to incorporate specimens from outside their geographic range of interest and some- times did not include the study of types from herbaria for which access to specimens is difficult, in such cases often leading to misapplication of the names regarding the specimens included in the treatments.