Jon P. Rebman

On the urgency of conservation on Guadalupe Island, Mexico: is it a lost paradise?

Guadalupe is an oceanic island located in the Pacific Ocean off Mexicos northwest coast. Its flora is composed of many plant species with more northern affinities and disjunctions from the California Floristic Province. Almost 16% of the native plant species are endemic, including two monospecific genera. However, the activities of feral goats released in the early 19th century have devastated most of the island. At present, at least 26 native plant species have disappeared from Guadalupe and many more seem to be on the threshold. To add to the problem, 61 exotic plant species have been documented on the island, many of which are aggressive weeds. In this paper, we propose eight types of environmental conditions for the island where different species assemblages of the pristine flora probably existed before their demise. It is of obvious urgency that the island needs a recovery plan and the first step should include the eradication of the feral goats. Only after this process can subsequent conservation measures be applied to ensure any restoration of this natural heritage. The recovery plan will need to address both spontaneous and human-induced plant repopulation processes from the main islands three southern islets, which have never been impacted by goats. Also, it may be necessary to reintroduce non-endemic, native plant taxa from the nearest Californian islands and the Mexican coast in order to reestablish some of the islands original diversity of plant species and communities. However, it should be noted that the forested communities do not have great hopes of recovering in the short term, since the ground water and soil conditions have been significantly altered. Furthermore, the eradication of an estimated 4000 goats still living on the island (year 2000) depends upon the vacillating motivation and will of Mexican authorities.

Analysis of the non-native flora of Ensenada, a fast growing city in northwestern Baja California

Urbanized areas show a high proportion of non-native plants and can work as dispersal points to the surrounding areas. Ensenada is a fast growing city located in the northwestern peninsula of Baja California (Mexico). It is the southern extreme of a bi-national, coastal urban corridor that extends from Los Angeles, California south to Ensenada. This corridor is part of the biodiversity hotspot of the California Floristic Province. The aim of this study was to analyze the composition and distribution of the spontaneous flora in the city of Ensenada. We systematically sampled two differentiated urban environments, vacant lots and arroyos, in 2006 and 2007. We found a total of 158 plant species, 61% of them were non-native species. Arroyo areas showed higher non-native species richness than vacant lots (21.9 vs. 13.6 species/transect) and could be potential dispersal vectors for non-native species to natural areas outside of the city, or in the reverse direction also.

Seven New Cacti (Cactaceae: Opuntioideae) From The Baja California Region, México

Abstract As a result of the authors doctoral biosystematic study of the genus Cylindropuntia in Baja California, plus subsequent field exploration and continued taxonomic research on the flora of this region in northwestern México, various new cactus taxa have been discovered. Seven new cacti including six chollas (Cylindropuntia alcahes (F. A. C. Weber) F. M. Knuth var. gigantensis Rebman, C. alcahes var. mcgillii Rebman, C. cedrosensis Rebman, C. ganderi (C. B. Wolf) Rebman & Pinkava var. catavinensis Rebman, C. libertadensis Rebman, and C. waltoniorum Rebman) and one new species of prickly-pear (Opuntia clarkiorum Rebman) endemic to the Baja California peninsula and adjacent islands are described here for the first time. Distribution, associated vegetation, rarity, affinities to other related species, botanical illustrations, and various keys for identification of these cacti in the region are also presented. Resumen Como resultado del estudio biosistemático doctoral del autor del género de Cylindropuntia en Baja California, más exploración de campo y la posterior investigación taxonómica continúa en la flora en el noroeste de México, se han descubierto varios taxones de cactus endémica de esta región. Siete nuevos cactáceas incluyiendo seis chollas (Cylindropuntia alcahes (F. A. C. Weber) F. M. Knuth var. gigantensis Rebman, C. alcahes var. mcgillii Rebman, C. cedrosensis Rebman, C. ganderi (C. B. Wolf) Rebman & Pinkava var. catavinensis Rebman, C. libertadensis Rebman, y C. waltoniorum Rebman) y una nueva especie de nopal (Opuntia clarkiorum Rebman) endémica de la península de Baja California y las islas adyacentes se describen aquí por primera vez. Se presentan la distribución, vegetación asociada, rareza, afinidad con otras especies en el género, ilustraciónes botánicas del nuevos taxónes, y varias claves por la identificación de estos cactáceas en la región.

CALYPTRIDIUM PARRYI VAR. MARTIRENSE (MONTIACEAE), A NEW TAXON ENDEMIC TO THE SIERRA DE SAN PEDRO MARTIR, BAJA CALIFORNIA, MEXICO

Abstract Calyptridium parryi var. martirense is described as new. Here we present quantitative measurements and statistical analyses of a number of morphological features that demonstrate the distinctiveness of this new taxon. The new variety differs from the others in having shorter fruits (3.1–4.1 mm) and a correspondingly smaller fruit length to sepal length ratio (1.0–1.4). The capsule is also the widest (1.4–2.2 mm) and the sepals the longest (2.4–3.9 mm) of any other C. parryi variety. Calyptridium parryi var. martirense is currently known only from high elevation locations (1900–2630 m) in the Sierra de San Pedro Mártir, Baja California, Mexico.

Recognition of Two Species in Eremocarya (Boraginaceae): Evidence From Fornix Bodies, Nutlets, Corolla Size, and Biogeography

Abstract Eremocarya (Boraginaceae), a recently resurrected segregate of the genus Cryptantha, has generally been recognized as containing a single species, E. micrantha, with two varieties. Here we present evidence that these two varieties are distinct in a number of features and that they should be treated as separate species: Eremocarya lepida and E. micrantha. Eremocarya lepida differs from E. micrantha in having a significantly greater corolla limb width, nutlet length, maximum nutlet width, and maximum nutlet width: apical nutlet width. Eremocarya lepida also has prominent yellow fornices near the apex of the corolla throat, whereas fornices are absent and the fornix region lacks pigmentation in E. micrantha. In addition, we report the discovery of clusters of minute (ca. 0.1 mm long), transparent, stalked, ellipsoid structures born near the apex of the inner corolla tube that are associated with the five corolla fornices, these being unique to E. lepida. These structures, which we term “fornix bodies,” are of unknown chemistry and function, but they may possibly have a role in the pollination of the showier, larger-flowered E. lepida. In addition to these morphological characters, the two species differ in distribution, elevation, and plant community/vegetation. Eremocarya lepida occurs at higher elevation in chaparral, coniferous woodland, and high desert scrub of southern California and northern Baja California, México. Eremocarya micrantha occurs at lower elevations in desert habitats of Arizona, California, New Mexico, Texas, Oregon, and Utah in the United States, and Baja California and Sonora in México. All of these data strongly support recognition of two species in Eremocarya.

Cryptantha wigginsii (Boraginaceae): A Presumed Extinct Species Rediscovered

Abstract Cryptantha wigginsii I.M. Johnston (Boraginaceae) had previously been known from a single collection made in April 1931, at a locality 18 miles south of Tijuana, Baja California, Mexico. This species is distinctive and unique in the genus in having nutlets with a surface that is smooth and glossy near the base and densely tuberculate at the apex. Because of the absence of subsequent collections, the species was presumed extinct. However, a population of C. wigginsii was recently discovered in Carlsbad, San Diego Co., California, constituting a new county, state, and country plant species record. Subsequent field investigations and study of (mis-identified) Cryptantha specimens at several California herbaria has turned up additional documented populations of this species in the USA and coastal northwestern Baja California, Mexico. In addition to the three adjacent Carlsbad populations and the type locality in Baja California, populations known to date include: 1) five from Santa Catalina Island, L...

A New Species of Cryptantha (Boraginaceae) from the Sierra De San Pedro Mártir, Baja California, Mexico

Abstract Cryptantha martirensis M. G. Simpson & Rebman is described as new, being endemic to high elevations of the Sierra de San Pedro Martir of Baja California, Mexico. It is sparse to common in the understory of coniferous woodland and in montane arroyos, slopes, and ridges in sandy to gravelly granitic substrates. This new species is similar to C. muricata (Hooker & Arnott) A. Nelson & J. F. Macbride in having nutlets with a shallow, dorsal ridge. It differs from the three recognized varieties of C. muricata in having a combination of tall and virgate primary stems with short and clustered inflorescence units; stems with mostly appressed and a few sparse, fine, spreading trichomes; a small corolla limb; and relatively large nutlets with dorsal tubercles that are low, rounded, and few per area. Quantitative evidence justifying these differences is summarized.

Where to conserve? Plant biodiversity and endemism in mediterranean Mexico

Six regions of northwestern (NW) Baja California (Sierra de Juárez, Sierra de San Pedro Mártir, Punta Banda, Colonet, San Quintín and Valle Tranquilo) were compared for their floristic diversity. Checklists for each region were analyzed by their total, native, and endemic floras to give measures of floristic similarity and overlap, and to identify the strongest gradients affecting species distributions. Each region was floristically distinct, with significant variation in the distribution of state endemic taxa. The six regions are readily differentiated by their geographical position in a Principal Components Analysis. The strongest gradients were (a) the W–E gradient from the coast to the mountains and (b) the latitudinal gradient from N to S. These six adjacent regions are found within a local and global biodiversity hotspot that is subject to intense conservation challenges. Conservation of many areas is essential to adequately preserve the diversity of locally endemic taxa with restricted ranges, yet the coast lacks any protected areas at the state and federal level. Private reserves such as Reserva Natural San Quintín may be critical to the conservation of regionally endemic taxa.

Three Edaphic-Endemic Ceanothus (Rhamnaceae) New to Science

Abstract North America is home to approximately 55 species of Ceanothus (Rhamnaceae), more than 30 of them endemic to the biodiversity hotspot known as the California Floristic Province. Although several species of Ceanothus are widespread in North America, most of the species are micro-endemics, known from a small number of occurrences and generally associated with special ecological conditions. As botanical exploration of North America continues, it is expected that more such micro-endemics will be discovered. However, field work is not the only way in which additional Ceanothus diversity will come to light; the strongly variable morphology of Ceanothus means that specimens are difficult to identify, and many biological entities that probably deserve taxonomic recognition are already represented in herbaria but have not yet been recognized as new. We here describe three new taxa of Ceanothus, two initially noted among existing collections, and another discovered during botanical exploration in San Diego County. All three are edaphic micro-endemics found only in the southern California Floristic Province, California. These include 1) Ceanothus foliosus var. viejasensis D. O. Burge&Rebman, restricted to gabbro-derived soils on ViejasMountain in SanDiego County, 2) Ceanothus pendletonensis D. O. Burge, Rebman, &M. R. Mulligan, found on granodiorite-derived soils of the central Santa Margarita Mountains in San Diego County, and 3) Ceanothus thyrsiflorus var. obispoensis D. O. Burge, endemic to rhyolite-derived soils near Hollister Peak in San Luis Obispo County.

A New, Large-Flowered Variety of Eremocarya micrantha (Boraginaceae)

Abstract Eremocarya (Boraginaceae), a resurrected segregate of the genus Cryptantha, has recently been recognized as containing two species: E. lepida and E. micrantha. These two species differ in nutlet shape, nutlet size, and features of the corolla, including limb width, presence or absence of a prominent yellow coloration at the fornices of the corolla center, and, perhaps most importantly, presence or absence of distinctive “fornix bodies” at the corolla mouth. Here we present evidence for a large-flowered form of E. micrantha that we argue should be treated as a new taxonomic variety, which we call E. micrantha var. pseudolepida. In nutlet morphology, E. micrantha var. pseudolepida is very similar to E. micrantha var. micrantha and different from E. lepida. Eremocarya micrantha var. pseudolepida differs from E. micrantha var. micrantha and is similar to E. lepida in corolla limb diameter and in having a tendency to possess a prominent yellow coloration in the corolla throat. However, E. micrantha var. pseudolepida lacks the distinctive fornix bodies of E. lepida. This new variety of E. micrantha is generally geographically discrete and allopatric relative to E. micrantha var. micrantha, with virtually all known populations occurring in Baja California, Mexico, between approximately 28° and 32° north latitude. However, two contiguous populations of a large-flowered E. micrantha were discovered in southeastern Arizona. In addition, one population of E. micrantha var. pseudolepida, in the central part of its range in Baja California, appears to be sympatric with a disjunct population of E. micrantha var. micrantha. We feel that the morphological distinctiveness and near geographic discontinuity of this entity warrants its status as a new taxon. Future molecular studies will be needed to evaluate the phylogeographic history of this intriguing complex of plants in order to evaluate both character evolution and taxonomic delimitation.