A REVISION OF DIDYMODON Juan A. JimeÂnez, Rosa M. Ros, 2 SECTION FALLACES (MUSCI, MarõÂa J. Cano, and Juan Guerra POTTIACEAE) IN EUROPE, NORTH AFRICA, MACARONESIA, AND SOUTHWEST AND CENTRAL ASIA1 ABSTRACT Didymodon sect. Fallaces (Musci, Bryopsida) is taxonomically revised for Europe, North Africa, Macaronesia, and Southwest and Central Asia. Nine species are recognized. Didymodon planotophaceus, D. spadiceus var. siluricus, and Didymodon ceratodonteus are newly synonymized with D. tophaceus; D. barbuloides is a new synonym referred to D. spadiceus, and Trichostomum rigidulum var. paludosa to D. fallax. Lectotypes for Barbula adriatica, B. falcifolia, B. insidiosa, B. kneuckeri, B. rigidicaulis, B. serpenticaulis, B. sinensi-fallax, Didymodon barbuloides, D. bosniacus, D. giganteus, D. levieri, D. maximus, D. rufus, D. spadiceus, D. spadiceus var. siluricus, D. tophaceus, D. tophaceus var. breidleri, Limneria viridula, and Trichostomum rigidulum var. paludosa are designated here. Didymodon asperifolius and D. tophaceus are reported for the ®rst time from the Caucasus and Mauritania respectively. Descriptions, a taxonomic key, as well as LM and SEM photographs are included. Key words: Asia, Didymodon, Europe, Macaronesia, North Africa, Pottiaceae, taxonomy. Didymodon Hedw. is a genus of the moss family Chen, 1941; Nyholm, 1989; Smith, 1978; KuÈrsch- Pottiaceae that includes approximately 122 spe- ner, 2000). Saito (1975) differentiated Didymodon cies worldwide, with the greatest diversity in tem- and Barbula for the ®rst time by gametophytic perate and mountainous regions (Zander, 1993). characters. He principally used the axillary hairs The genus was described by Hedwig (1801) to in- of the leaves for discriminating both genera. The clude three species, only one of which is currently axillary hairs in Didymodon have one or two brown accepted in the genus: D. rigidulus. The remain- basal cells, while in Barbula the hairs are hyaline ing species correspond to genus Ditrichum Ham- throughout. Later Zander (1993), in his world pe. monograph of the Pottiaceae, expanded the delim- The genus concept of Didymodon has been in itation between Didymodon and Barbula. dispute, especially as regards the morphological Besides this controversy concerning Barbula, the delimitation of Didymodon versus Barbula Hedw. segregation of some Didymodon species into other The taxonomic differences between the two genera closely related genera, such as Geheebia Schimp., have long been based on peristome characters: in Oxystegus (Limpr.) Hilp., Husnotiella Cardot, and Barbula formed by long and twisted teeth and in Trichostomopsis Cardot, is also of note. However, Didymodon by short and straight teeth. Since these according to Saito (1975) and Zander (1978, 1993) characters separated gametophytically closely re- all of these have the morphological features as- lated species of the genus Didymodon and Barbula signed to Didymodon. The molecular data support (e.g., D. fallax and D. spadiceus), the differentiation this opinion. Werner et al. (2004a) sequenced cp between both genera was generally abandoned rps4ofDidymodon rigidulus Hedw., Geheebia gi- (Dixon, 1924; MoÈnkemeyer, 1927; Hilpert, 1933; gantea (Funck) Boulay, Oxystegus sinuosus (Mitt.) 1 We thank the curators of the herbaria and the collectors who sent us material on loan: B, BCB, BM, BP, BR, C, CAIA, CAME, CANM, CGE, CLU, COI, DUKE, E, FCO, FI, G, GB, GDA, GJO, GZU, H, HBG, IRAN, JE, L, LE, LISU, M, MA, MO, MUB, NMW, NY, O, PAMP, PC, PO, PRC, RO, S, SINU, SOM, VAL, VIT, W, WB, WU, Z, herbarium T. L. Blockeel, herbarium A. Cogoni, herbarium R. DuÈll, herbarium W. Frey, herbarium J. MartõÂnez-Abaigar, herbarium R. B. Pierrot, herbarium M. Sabovljevic, herbarium R. Skrzypczak, herbarium C. C. Townsend. This work has been carried out with ®nancial support from MCYT of Spain (Projects BOS2001-0276 and BOS2000-0296-C03- 01) and ``FundacioÂn SeÂneca'' of Murcia (PI-15/00762/FS/01). 2 Departamento de BiologõÂa Vegetal, AÂ rea de BotaÂnica, Facultad de BiologõÂa, Campus de Espinardo, E-30100 Murcia, Spain. [email protected]. ANN.MISSOURI BOT.GARD. 92: 225±247. 2005. 226 Annals of the Missouri Botanical Garden Hilp., and Trichostomopsis australasiae (Hook. & MO, MUB, NMW, NY, O, PAMP, PC, PO, PRC, RO, Grev.) H. Rob and observed that all these species S, SINU, SOM, VAL, VIT, W, WB, WU, Z, herbar- are closely related. More precise data have been ium T. L. Blockeel (Shef®eld, United Kingdom), obtained when sequencing the nrITS region of a herbarium A. Cogoni (Cagliari, Italy), herbarium R. high number of taxa, which show that the genus DuÈll (Bad MuÈnstereifel, Germany), herbarium W. Didymodon is monophyletic after including the for- Frey (Berlin, Germany), herbarium J. MartõÂnez- merly segregated species and is clearly separated Abaigar (LogronÄo, Spain), herbarium R. B. Pierrot from Barbula (Werner et al., 2004b, 2005). (Dolus d'OleÂron, France), herbarium M. Sabovljevic According to Zander (1993) Didymodon consists (Belgrade, Serbia, and Montenegro), herbarium R. of ®ve sections: section Asteriscium (MuÈll. Hal.) R. Skrzypczak (Montbrison, France), herbarium C. C. H. Zander, section Fallaces (De Not.) R. H. Zander, Townsend (Twickenham, London, United Kingdom). section Ru®dulus (Chen) R. H. Zander, section Di- Specimens were examined in a 2% potassium dymodon, and section Vineales (Steere) R. H. Zan- hydroxide solution. der. Leaf areolation and ornamentation was studied Studies of Didymodon in Europe are scant, even using a Jeol JSM-6100 SEM at the University of if we include those of DuÈll (1984), DuÈll-Hermanns Murcia. The material was ®xed in 3% glutaralde- and DuÈll (1985), and KucÏera (2000), on central Eu- hyde with 0.1M cacodylate buffer at 48C, washed ropean species, and of KucÏera (2002), on northern in cacodylate and saccharose buffer, dehydrated in European species. No study has until now included an increasing acetone gradient (30%, 50%, 70%, North African taxa or those from Central and South- 90%, 100%), critical-point dried, and sputtered west Asia. Recent years have seen the publication with a gold layer 200±300 AÊ thick. of ¯oristic studies or checklist studies in this area World distributions are provided; major political (Frey & KuÈrschner, 1991; Ros et al., 1999; El-Saa- divisions for countries are included when the in- dawi et al., 1999; KuÈrschner, 2000; Cano et al., formation was available. 2002), which have pointed to the existence of nu- merous endemisms and taxa described or collected TAXONOMIC HISTORY once during the ®rst half of the 20th century and then forgotten. Many more works have been pub- Like most of the species of Didymodon, those lished on this genus in North America and Mexico belonging to section Fallaces were attributed to dif- (Zander, 1978, 1981, 1994), East Asia (Chen, ferent genera (Trichostomum Bruch, Tortula Hedw., 1941), and Japan (Saito, 1975; Noguchi, 1988). Geheebia Schimp.), although, as previously men- Recognizing the overall scarcity of information, tioned, these species were especially considered we have carried out a taxonomic revision of the members of the genus Barbula. This remained the section Fallaces in Europe, North Africa, Macaro- case until Didymodon was delimited morphologi- nesia, and Southwestern and Central Asia. Nine cally (Saito, 1975; Zander, 1978). species belong to this section in this geographic The ®rst subgeneric treatment of Didymodon was area: Didymodon asperifolius (Mitt.) H. A. Crum, made by Saito (1975), who recognized two sections Steere & L. E. Anderson, D. fallax (Hedw.) R. H. for the Japanese species: section Graciles (Milde) Zander, D. ferrugineus (Schimp. ex Besch.) M. O. K. Saito and section Didymodon. The section Grac- Hill, D. giganteus (Funck) Jur., D. maschalogena iles was characterized by the rounded-triangular (Renauld & Cardot) Broth., D. maximus (Syed & stem, basal margins of leaves long-decurrent, and Crundw.) M. O. Hill, D. spadiceus (Mitt.) Limpr., D. cells of the adaxial surface of the costa linear-ob- tomaculosus (Blockeel) M. F. V. Corley, and D. to- long. This section included Didymodon giganteus, phaceus (Brid.) Lisa. D. eroso-denticulatus, and D. rigidicaulis (MuÈll. Hal.) K. Saito. Zander (1978) added ®ve species to MATERIALS AND METHODS section Graciles (Didymodon fallax, D. laevigatus (Mitt.) R. H. Zander, D. michiganensis K. Saito, D. All available types and numerous collections of leskeoides K. Saito, and D. tophaceus) and expanded Didymodon sect. Fallaces from Europe, Africa, the characterization of this section, adding as im- North America, and Asia have been studied. This portant characters the spreading to often strongly revision is based on 1130 specimens deposited in recurved leaves when moist, unistratose upper lam- the following institutional and personal herbaria: B, inal cells, and adaxial stereid band usually present. BCB, BM, BP, BR, C, CAIA, CAME, CANM, CGE, Zander (1979) found an earlier name, Tortula sect. CLU, COI, DUKE, E, FCO, FI, G, GB, GDA, GJO, Fallaces De Not., available at the sectional level GZU, H, HBG, IRAN, JE, L, LE, LISU, M, MA, for section Graciles, so he proposed the new com- Volume 92, Number 2 JimeÂnez et al. 227 2005 Didymodon Section Fallaces bination Didymodon sect. Fallaces and synony- Didymodon sect. Fallaces (De Not.) R. H. Zan- mized section Graciles with this section. Zander der, Phytologia 44: 209. 1979. Tortula sect. (1993) added another morphological character to Fallaces De Not., Mem. Reale Accad. Sci. To- de®ne the section as the KOH color reaction