A New Species of Linanthus (Polemoniaceae) from San Bernardino County, California

Linanthus bernardinus is described as new from San Bernardino County, California. It is morphologically similar to L. killipii and L. orcuttii subsp. pacificus but differs from plants of these taxa in height, corolla length, seed morphology, and habitat. Linanthus bernardinus can be found growing in vernally moist areas within Joshua tree woodland, often in shallow depressions, or on gentle slopes, in decomposed granite sand that is surrounded by large granite boulder fields.


INTRODUCTION
The novelty described here was discovered in 2005 when a single specimen that was misidentified as Leptosiphon breviculus (A.Gray) J.M.Porter & L.A.Johnson was found in the RSA herbarium ( Fig. 1-4). The specimen was re-identified to the genus Linanthus Benth. (Polemoniaceae), but it could not be satisfactorily identified to species. It was morphologically similar to Linanthus killipii H.Mason and L. orcuttii (A.Gray ex Parry) Jeps. subsp. pacificus (Milliken) H.Mason. However, the plant differed from plants of both species in height, corolla length, seed color, and the habitat from which it was collected (Table 1). Additional specimens of this taxon were located at RSA and UCR; most of these had been misidentified as L. orcuttii. Evidence from field and herbarium studies is presented here to provide the basis for the recognition of this newly described taxon.

Taxonomic Overview of Linanthus
The genus Linanthus is endemic to North America and contains at least 25 species including the one newly described here (Porter and Johnson 2000). The genus is composed of annual and perennial species that are morphologically diverse, especially with respect to leaf morphology and inflorescence structure (Porter and Johnson 2000;Patterson and Porter 2012). Based on molecular phylogenetic studies, Linanthus as currently circumscribed forms a monophyletic group and includes members of Grant's sections Linanthus and Dianthoides, along with taxa formerly placed in genus Leptodactylon Hook. & Arn. and several species previously included in Gilia Ruiz & Pav. (Bell and Patterson 2000;Porter and Johnson 2000).

MATERIALS AND METHODS
This study is supported by field observations and study of herbarium specimens. Field studies conducted in 2010 and 2011 included sampling populations of the newly described taxon, L. killipii, and L. orcuttii subsp. pacificus. Herbarium specimen records, databases (CNDDB 2012;CCH 2012;SEINet 2012), and literature reports were used to identify populations for field surveys. At each field site, data recorded included exact location (via Global Positioning System), habitat characteristics (i.e., elevation, slope, aspect, microhabitat, vegetation association, and associated species), distinguishing morphological characteristics, and conservation status (i.e., existing or potential threats or disturbances). Photographs were taken of living plants. Seeds and herbarium specimens were collected for later study. Conservation assessments are based on criteria outlined by the California Native Plant Society (CNPS) Inventory of Rare and Endangered Plants (2012), and Natureserve (2012).
Line drawings presented in the treatment are based on photographs, herbarium material, and descriptions provided to the illustrator. Vegetative and floral measurements provided in the descriptions are all inclusive ranges from study of herbarium specimens. Herbarium specimens were databased and georeferenced to create accurate distribution maps, and maps were prepared in ArcGIS 10.0 (ESRI 2012). Leaves opposite, sessile to short (1 mm) petiolate, often sheathing at the base; blades 1.5-7 (10) mm long, palmately lobed with (3) 4-5 linear divisions, adaxial surface densely villous, abaxial surface more sparsely villous, margins entire. Inflorescence a cyme, generally in 1-3 flowered units. Floral bracts leaf-like, but larger, 3-10 (12) mm long. Pedicels sessile to short (to 1 mm long). Flowers diurnal, opening in full sunlight. Calyx 5-7 mm long, campanulate to narrowly urnshaped, with stipitate glands, sparsely villous proximally, lobes erect, costa green and herbaceous, darker and narrower than the hyaline intercostal regions, the sinuses narrowly V-shaped and divided less than half way to the base. Corolla 13-25 mm long, funnelform, lobes white to cream or pale lavender-pink, with a solitary maroon to red narrowly ellipse-shaped spot at the base of each lobe, apices apiculate, throat white, tube maroon to purple, glabrous throughout, tube 6-14 mm long, cylindric, expanding gradually to the limb. Stamens equal, 3-5 mm long; anthers yellow, glabrous, included, pollen yellow. Gynoecium 9-16 mm long; ovary narrowly ovoid, green; style and stigma yellow, glabrous; stigma slightly exserted. Capsules ellipsoid, 2.5-3.5 mm long, 2-10 seeds per locule. Seeds 0.5-1 mm long, irregularly shaped, sometimes angular and prismlike, light brown with net-like seed coat, producing a small amount of mucilage when wetted. Flowering occurs between March and early May, fruiting between late April and May. Distribution and habitat.-Linanthus bernardinus (Fig. 1-4) is endemic to San Bernardino County, California. This taxon is known primarily from a small mountain range called the Sawtooths located 3.5 air mi NW of Yucca Valley, E of the San Bernardino Mountains and W of the Little San Bernardino Mountains (Fig. 5). Plants occur in Joshua tree  Etymology.-Linanthus bernardinus is named for the San Bernardino Mountains and San Bernardino County, California, where this species is endemic. We suggest the common name Pioneertown linanthus because the unincorporated village of Pioneertown in San Bernardino County is situated at the center of all known occurrences of this species (Fig. 5). Linanthus bernardinus is known from 11 occurrences in a 27 km 2 (10 sq mi) area (Fig. 5) and is thus a narrow endemic. Therefore, threats to known occurrences may have a significant impact to its long-term conservation. Linanthus bernardinus is threatened by competition with non-native plant species, housing development in the vicinity of Pioneertown, and also potentially by renewable energy development.
Based on criteria used by NatureServe (2012) and CNPS (2012) to establish conservation status ranks, we recommend that L. bernardinus be considered for the global rank of G2: imperiled-''at high risk of extinction or elimination due to very restricted range, very few populations, steep declines, or other factors'' and a California Rare Plant Rank of 1B.2, or fairly threatened in California with 20-80% of occurrences threatened. Linanthus bernardinus occurs on land managed by the Wildlands Conservancy (Pioneertown Mountains Preserve), the State of California (University of California Burns Piñ on Ridge Reserve), and private property. This species has potential to occur on lands managed by the Bureau of Land Management because it is known from properties adjacent to BLM holdings.
Habitat for L. bernardinus was impacted in the summer of 2006 by the Sawtooth Complex Fire (Fig. 6). The fire was ignited by lightning and burned approx. 250 km 2 (96 sq mi; Cal Fire 2012) in the region. For five years following the fire, land managed by the Wildlands Conservancy in the Pioneertown Mountain Preserve was closed to the public for habitat rehabilitation. Over the course of the study, the vegetation, including Joshua trees and oaks, were observed resprouting, and vegetation was in the early stages of recovery. The indirect effects of fire could potentially threaten L. bernardinus if nonnative species were to become established and invade habitat following fire. Competition with non-native species is a potential threat to L. bernardinus.