Phytotaxa 158 (1): 105–110
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Copyright © 2014 Magnolia Press
ISSN 1179-3155 (print edition)
Article
PHYTOTAXA
ISSN 1179-3163 (online edition)
http://dx.doi.org/10.11646/phytotaxa.158.1.9
Didymodon californicus (Pottiaceae), a new species from California, U.S.A.
JUAN A. JIMÉNEZ1, DAVID TOREN2 & JAMES R. SHEVOCK2
1
Departamento de Biología Vegetal (Botánica), Facultad de Biología, Universidad de Murcia, E-30100 Murcia, Spain.
E-mail: jajimene@um.es
2
Department of Botany, California Academy of Sciences, 55 Music Concourse Dr., Golden Gate Park, San Francisco, CA 94118
U.S.A.
Abstract
Didymodon californicus is described as a new species from California, U.S.A. The new taxon is included in sect.
Vineales (Steere) R.H. Zander, and characterized mainly by its large size, lanceolate leaves, plane margins throughout,
the red to reddish orange color in KOH, costa ending below the apex, a hyaline area of rectangular cells on ventral
surface of the costa, cross-section of the costa with numerous guide cells in 2–3 layers and without ventral stereids, and
smooth to low-papillose laminal cells. Drawings and light microscope photographs of the main characters are given, and
possible confusion with other closely related taxa is discussed.
Key words: Didymodon, mosses, rheophytes, taxonomy, Western North America
Introduction
Didymodon Hedwig (1801: 104) includes approximately 122 species and represents one of the largest genera of
Pottiaceae (Zander 1993). The genus has a cosmopolitan distribution, with an important center of diversity in the
western North America. In the past two decades, two new taxa, D. norrisii Zander (1999: 112) and D. eckeliae
Zander (2001: 298) were described from California and subsequently located beyond the state. Didymodon
bistratosus Hébrard & Pierrot (1994: 354), also collected in California, was new to the New World (Zander et al.
2005). The North American species of Didymodon were recently revised by Zander (2007), who recognized 26
species.
While examining material of western North American Didymodon, several Californian specimens were found
that did not match the concept of any known species of the genus, and are consequently described as a new species.
Material and methods
Voucher specimens of the new species are deposited in CAS, MO, MUB and NY. The samples were studied with
the typical anatomical and morphological methods applied for the Pottiaceae (Zander 1993). In addition, most of
the type material of taxa attributed to this genus in the world has been studied by the first author. Microscopic
examinations and measurements were taken with an Olympus-BX41 light microscope, while microphotographs
were obtained with a Jenoptik ProgRes C7 camera mounted on this microscope. Specimens were examined in 2%
potassium hydroxide.
Description
Didymodon californicus J. A. Jiménez, Toren & Shevock sp. nov. (Figs. 1, 2)
Diagnosis: Didymodon californicus differs from the otherwise similar Didymodon vinealis Bridel (1827: 830) Zander (1978:
Accepted by Lars Söderström: 6 Jan. 2014; published: 30 Jan. 2014
105
Didymodon eckeliae, a species disjunct between the Pacific coast of North America and the Mediterranean
region (Zander 2007; Jiménez & Cano 2012), is easily distinguishable from the new species in having bistratose
leaf margins that are broadly crenulate to notched above midleaf as well as a more long-lanceolate leaf outline.
Some morphological characters shown by D. californicus, such as the size and color of the plants, the shape of
the leaves, plane leaf margins above midleaf, the color of the lamina with KOH and epapillose laminal cells are
also found in the Neotropical D. laevigatus (Mitten 1869: 160) Zander (1978: 29). However, this species has
elongate cells on the upper ventral surface of the costa and two costal stereid bands, while in the new species the
upper ventral surface cells of the costa are subquadrate or oblate and the costa lacks a ventral stereid band.
Acknowledgments
We thank Ed Dearing for support and logistics while conducting field work in Lake County. We also thank M. J.
Cano for her review of a first version of the manuscript. JAJ is grateful for financial support from the Spanish
“Ministerio de Ciencia e Innovación” [project CGL2010-15959/BOS co-financed by FEDER and “Ramón y Cajal”
Subprogram co-financed by the European Social Fund] and “Fundación Séneca-Agencia de Ciencia y Tecnología
de la Región de Murcia” [project 11932/PI/09].
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Phytotaxa 158 (1) © 2014 Magnolia Press
JIMÉNEZ ET AL.
Juan Pablo Mariño Jimenez