Phytotaxa 360 (3): 220–236 http://www.mapress.com/j/pt/ Copyright © 2018 Magnolia Press ISSN 1179-3155 (print edition) Article PHYTOTAXA ISSN 1179-3163 (online edition) https://doi.org/10.11646/phytotaxa.360.3.3 On the taxonomic status of the genus Dichodon (Caryophyllaceae: tribe Alsineae): morphological and molecular evidence reassessed ZAHRA ARABI1, FARROKH GHAHREMANINEJAD1, RICHARD K. RABELER2, IRINA SOKOLOVA3, GÜNTHER HEUBL4 & SHAHIN ZARRE5,* 1 Department of Plant Biology, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran 2 University of Michigan Herbarium – EEB, 3600 Varsity Drive, Ann Arbor, MI 48108-2228, USA 3 Herbarium of Vascular Plants of the Komarov Botanical Institute (LE), Prof. Popova Str. 2, St. Petersburg, 197376, Russia 4 Systematic Botany and Mycology, Department Biology I, Ludwig-Maximilians-Universität and GeoBio Center LMU München, Menzinger Str. 67, D-80638, München, Germany 5 Center of Excellence in Phylogeny and Department of Plant Science, School of Biology, College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran *Author for correspondence Abstract The status of the genus Dichodon has long been debated, and its taxonomic position in tribe Alsineae has been changed during the time from a section or subgenus in Cerastium to genus sister to Holosteum. This group comprises important members of wet meadows in alpine and subalpine vegetation of Europe, arctic regions, and SW-Asia plus one species known as a weed in N-America, and a further one occuring in mountains of Taiwan. In order to clarify the taxonomic questions concerning this group and its species delimitation, we constructed phylogenetic trees, selecting several species belonging to tribe Alsineae as representatives of major lineages of this tribe as well as several accessions of Dichodon. Morphological studies focused more intensively on members of Dichodon using herbarium specimens and direct field examinations. The results confirm those of recent molecular phylogenetic studies, indicating Dichodon as a monophyletic genus sister to Holosteum and not Cerastium. In addition, the obtained cladograms support five distinct groups in Dichodon corresponding to five species of this genus we recognize in Iran, the focal area of this study. Seed micromorphology provides strong support for the recognition of Dichodon as a separate genus, but it is not informative at species and subspecies ranks due to constancy of most of seed characters within the genus. As part of this study, a new species—Dichodon alborzensis—is described, D. kotschyi is reported in Iran for the first time, and Cerastium schischkinii is placed in synonymy (new synonymy) under D. kotschyi. Keywords: Cerastium, Holosteum, Iran, phylogeny, seed micromorphology, systematics Introduction Caryophyllaceae Juss. (Caryophyllales Juss. ex Bercht. & J. Presl) is a cosmopolitan family with a center of diversity in the Mediterranean and Irano-Turanian regions including about 3000 species assigned to about 100 genera (HernándezLedesma et al. 2015). Greenberg & Donoghue (2011) demonstrated the monophyly of this family using molecular data. However, the infraclassification of Caryophyllaceae is still partially unresolved and several tribes and genera are critical from both taxonomical and nomenclatural points of view and need further study (see e.g., Dillenberger & Kadereit 2014, Iamonico 2016, Iamonico & Domina 2015) including the tribe Alsineae Lamarck & Candolle (1806: 392), and the genus Dichodon (Bartling ex Reichenbach 1832: 785) Reichenbach (1841: 205). Based on traditional classification systems, the family is divided into three subfamilies, but recent molecular studies suggested a tribal rather than subfamilial classification, as none of the supposed subfamilies could be recovered as monophyletic (Harbaugh et al. 2010; Greenberg & Donoghue 2011). According to Bittrich (1993), tribe Alsineae includes 23 genera and 676−726 species, among which several ones are known as cosmopolitan weeds [e.g., Stellaria media (Linnaeus 1753: 272) Villars (1789: 615), Cerastium fontanum Baumgarten (1816: 425), C. glomeratum Thuillier (1799: 226), etc.] (Scheen et al. 2004, Harbaugh et al. 2010). Although the molecular studies led to an improved circumscription of tribe Alsineae, questions regarding the generic boundaries within the tribe still remain due to insufficient sampling of problematic or controversial taxa within some genera. 220 Accepted by Duilio Iamonico: 11 Jun. 2018; published: 17 Jul. 2018 The genus Dichodon was included in previous molecular phylogenetic studies with only two representative species [D. viscidus (Marschall von Bieberstein 1808: 342) Holub (1974: 273) and D. cerastoides (Linnaeus 1753: 422) Reichenbach (1842: 34)] by Scheen et al. (2004), and Greenberg & Donoghue (2011). The systematics of Dichodon are subject to two major challenges: the phylogenetic placement of the genus, and the species boundaries within Dichodon. The genus was previously treated as a subgenus of Cerastium subg. Dichodon (Bartling ex Reichenbach 1832: 785) Fenzl (1842: 396) or a section, i.e. C. sect. Dichodon (Bartling ex Reichenbach 1832: 785) Grisebach (1843: 207). The species of Dichodon were distinguished by the number of styles (3 vs. 5) and number of capsule teeth (6 vs. 10). Dichodon species are annual or perennial herbs, 2–20 cm tall, with delicate, linear to lanceolate-oblong leaves, petals deeply incised or notched/emarginated, and pistils 3-styled (rarely with 4 or 5 styles), capsules with 6 teeth, and seeds greyish yellow with a unique verrucate surface type (Fenzl 1842, Schischkin 1936, Ikonnikov 1973, Arabi et al. 2017). Dichodon are distributed in Arctic, C-Europe, and W-Asia and Iran, while one species (D. viscidus) is known as a common weed in disturbed areas in North America, and another one [D. parvipetalus (Hosokawa 1932: 227) Gang Yao (2016: 130)] is endemic to Taiwan. Although the aforementioned features are diagnostic for separating Dichodon from Cerastium, some are also shared by other genera of tribe Alsineae [e.g., Stellaria Linnaeus (1753: 421)], and circumscribing the genera in Alsineae is currently problematic due to the homoplastic nature of morphological characters which occur in many other groups of Caryophyllaceae [e.g., Arenaria Linnaeus (1753: 423) and its allies (Minuto et al. 2006, Fior & Karis 2007, Sadeghian et al. 2015), Minuartia Loefling in Linnaeus (1753: 89) and its allies (Dillenberger & Kadereit 2014, Conti et al. 2014, Iamonico 2015, Moore 2017), and tribe Caryophylleae (Lamarck & Candolle 1806: 386) (Pirani et al. 2014, Madhani et al. 2018)]. Dichodon was first published by Reichenbach (1841a: 205), while the first species names (D. anomalum Reichenbach (1841b: 34) and D. cerastoides Reichenbach (1841b: 34)] were listed in Reichenbach (1841b). Ikonnikov (1973) was the first recent author to accept Dichodon as separate genus. Currently, there are 16 specific epithets listed under the generic name Dichodon in The Plant List database (2010), mostly treated as synonyms of Cerastium. Among these species, three have been recently transferred to the genus Shivparvatia Pusalkar & D.K.Singh (2015: 81) (tribe Arenarieae Rohrbach 1872: 262), which were placed by Ikonnikov (1976) in Dichodon sect. Sikkimensis (Williams 1895: 600) Ikonnikov (1976: 116). Four other species should be removed; they were added when Löve and Löve (1976) transferred Cerastium sect. Strephodon Seringe (in Candolle, 1824: 414) to Dichodon. Dichodon anomalus is nomenclatural synonym of Stellaria viscida Marschall von Bieberstein (1808: 342). A recent report estimates five species to be recognized in Dichodon (Hernández-Ledesma et al. 2015). Considering Dichodon as a subgenus or section of Cerastium dates respectively to Fenzl (1842) who described two species under C. subg. Dichodon (Bartling ex Reichenbach 1832: 785) Fenzl (1842: 396), and Grisebach (1843) who placed those species in C. sect. Dichodon (Bartling ex Reichenbach 1832: 785) Grisebach (1843: 207) (the number of species in sect. Dichodon had been increased to five by Boissier) 1867). Möschl (1988), in Flora Iranica, listed three species under C. subg. Dichodon among which C. persicus Boissier (1843: 54) represents an endemic to Iran. From the micromorphological point of view, seed features have proven to be useful at various taxonomic ranks within Caryophyllaceae (Wofford 1981, Minuto et al. 2006, Amini et al. 2011, Kanwal et al. 2012, Mahdavi et al. 2012). Arabi et al. (2017) studied the reliability of the seed data as taxonomic evidence within Alsineae and provided valuable characters for delimitation of close genera, i.e. Cerastium, Holosteum Dillenius ex Linnaeus (1753: 88), Stellaria, and Dichodon, although the studied samples were not adequate to deduce the value of such characters for species delimitation. All things considered, it is clear that species delimitation in Dichodon is ambiguous and needs more detailed investigation to address the taxonomic problems. We conducted phylogenetic analyses using a richer sampling of this genus in addition to representative taxa of the main clades already known in tribe Alsineae. In addition, field studies were conducted by the first author in order to find new insights from morphology and habitat characteristics of these taxa in Iran that should help refining the species boundaries in Dichodon. More explicitly, the aims of this study are to address: 1) exact placement of the members of Dichodon and its taxonomic status, 2) the number of species that should be recognized in Dichodon in Iran, 3) evaluation of seed characters in separating taxa of Dichodon, and 4) presenting a diagnostic key for the Iranian taxa of Dichodon. Material and Methods Plant materials The sampling focused on tribe Alsineae (Caryophyllaceae). Representatives of all main clades recognized in tribe DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 221 Alsineae according to the results of recent molecular phylogenetic analyses of the family (Harbaugh et al. 2010, Greenberg & Donoghue 2011) were included. As the monophyly of the tribe has been confirmed in previous phylogenetic analyses, it was not assessed here. All species currently known to belong to Dichodon were included, except for Dichodon alaicus Adylov (1995: 79), described from Uzbekistan, and the recently described species of this genus from Taiwan (D. parvipetalus) for which no material was available. Lepyrodiclis Fenzl ex Endlicher (1840: 966) and Pseudostellaria Pax (1934: 318), known as early diverging clades in tribe Alsineae, were selected as outgroups using sequences obtained from Genbank (www.ncbi.nlm.nih.gov). Fresh materials of Dichodon spp. were collected from five provinces of Iran. Herbarium specimens from the herbaria M, MSB, and TUH (acronyms follow Thiers 2018+) were also used for detailed morphological studies as well as DNA extraction when fresh materials were not available. Voucher information is presented in Table 1. DNA extraction, amplification, alignment and phylogenetic analyses Phylogenetic analyses were performed using two DNA fragments, known as the most useful markers in the phylogeny of Caryophyllaceae (Pirani et al. 2012, Sadeghian et al. 2015, Madhani et al. 2018), i.e. the internal transcribed spacer (ITS) region of the nuclear ribosomal cistron (consisting of ITS1, the intervening 5.8S gene, and ITS2) and the plastid intron (rps16). DNA was extracted from the dried leaf materials using a NucleoSpin Plant DNA extraction kit (Macherey-Nagel, Düren, Germany) according to the manufacturers’ protocol. Amplification of the ITS region was performed using the primer pairs Leu1 (Vargas et al. 1998) and ITS4 (White et al. 1990). In some difficult cases ITS2 and ITS3 were used, as described by White et al. (1990). For the plastid region (complete intron rps16), we used the primers rpsF and rpsR2R or rpsF and rpsR3R (Oxelman et al. 1997, Petri & Oxelman 2011, Kool et al. 2012). All PCR amplifications were performed in a Thermocycler T-Personal 48 (Biometra, Göttingen, Germany), Primus 96 plus (MWG: Biotech, Ebersberg, Germany), or 2720 (Applied Biosystems, Carlsbad, CA, USA). Cycle sequencing was done using BigDye Terminator v.3.1, Cycle Sequencing Kit (Applied Biosystems). DNA samples were sequenced with an ABI3730 DNA Analyser 48-well capillary sequencer (Applied Biosystems). All sequences were first aligned using default parameters in Mafft v.7 (Katoh & Standley 2013) and then alignment errors were identified and manually edited in Mesquite v.2.75 (Maddison & Maddison 2010). Phylogenetic reconstruction analyses were performed using two most common approaches, Bayesian Inference (BI), and Maximum Parsimony (MP) approach. Alignments of the individual datasets (ITS and rps16) were analyzed separately without indel coding. Bayesian analyses of the individual matrices were conducted using the Markov Chain Monte-Carlo (MCMC) algorithm of MrBayes v.3.2 (Ronquist et al. 2012) on the CIPRES Gateway (Miller et al. 2011). The best nucleotide substitution model was selected using the Akaike information criterion (AIC) in jModelTest v.2.1.6 (Darriba et al. 2012). The general time reversible model of nucleotide substitution with gamma-shaped rate variation and a proportion of invariable sites (GTR+I+G) was the estimated best-fit model for ITS and a simpler model, GTR+G, was chosen for rps16. The number of MCMC generations was set to one million for each of the ITS and rps16 datasets. Trees were sampled every 1000 generations and the runs were stopped when the average standard deviation of split frequencies fell below the critical value of 0.01. The burn-in fraction was set to 10% according to the value obtained from Tracer v.1.5 (Rambaut & Drummond, 2007). Posterior probabilities (PPs) were calculated on the basis of the remaining trees. MP analysis was performed using PAUP* v.4.0b10 (Swofford 2003). An initial analysis was conducted with 1000 random addition cycles, with TBR branch swapping, retaining five most-parsimonious trees in each replicate. A second heuristic search with the same settings followed, starting from the trees in memory (Davis et al. 2004), retaining a maximum of 20000 trees. To assess branch support, 5000 bootstrap replicates were performed with one tree held per replicate. The Posterior Probability (PP) and Bootstrap (BS) values are shown above and below the branches, respectively. FigTree v.1.4 (Rambaut 2012) was used for tree presentation. As the obtained phylogenetic trees of both markers did not show significant topological difference, the datasets were also combined and the final analyses were conducted on this combined dataset. The obtained trees were similar to those gained from individual analyses; thus these results are used for detailed discussion and conclusion. Seed Micromorphology using Scanning Electron Microscopy (SEM) Mature seeds were removed directly from fruits of selected herbarium specimens deposited at M, MSB and TUH. For each taxon at least three specimens were examined by SEM. The voucher specimens for seed morphology are the same as those used for comparative sequencing (Table 1). For SEM analyses, dried seeds were mounted on aluminum stubs and sputter-coated with gold and examined using a Hitachi SU3500 (Japan) scanning electron microscope. We follow the terminology suggested by Barthlott (Barthlott 1981) and Stearn (Stearn 1983) for the seed surface ornamentation as recently applied for tribe Alsineae as whole (Arabi et al. 2017). Measurements given are the mean value of at least 10 seeds. 222 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. TABLE 1. Taxa, voucher specimens and herbarium data of selected species used in the phylogenetic analyses of Dichodon and related genera from Alsineae. Accessions obtained from Genbank are marked with asterisk. Collection data are given only for specimens used for DNA extraction in the present study. Taxa Locality Collector Herbarium number GenBank and acronym (ITS; rps16) Cerastium arvense L. Chile L. Gautier 3372 (M) MH219805; MH243535 Cersatium dichotomum L. Greece J. Tillich 4260 (MSB) MH219806; MH243536 Cerastium falcatum (Ser.) Bunge Afghanistan D. Podlech 11170 (M) MH219807; MH243537 Cerastium tomentosum L. Germany F. Schuhwerk 07/118 (M) MH219808; MH243538 Dichodon alborzensis Arabi & Zarre1 Iran, Prov. Alborz Z. Arabi 47420 (TUH) MH219809; MH243539 Dichodon alborzensis Arabi & Zarre2 Iran, Prov. Tehran Z. Arabi 47422 (TUH) MH219810; MH243540 Dichodon alborzensis Arabi & Zarre3 Iran, Prov. Mazandaran Z. Arabi 47424 (TUH) MH219811; MH243541 Dichodon cerastoides Rchb. Turkey, Prov. Erzurum T. Gregor & L. Meierot 6636 (M) MH219812; MH243542 Dichodon cerastoides Rchb. Germany, Prov. Swabia A. Mayer 24 (M) MH243513; – Dichodon viscidus (M.Bieb.) Holub 1. Spain, Riocabado B. Casaseca & E. Rico 17867 (MSB) MH219814; MH243543 Dichodon viscidus (M.Bieb.) Holub 2. United States, Illinois P. Shildneck C-13733 (M) MH219815; MH243544 Dichodon kotschyi (Boiss.) Ikonn.1 Iran, Prov. Azerbaijan Z. Arabi 47419 (TUH) MH219816; MH243545 Dichodon kotschyi (Boiss.) Ikonn.2 Iran, Prov. Mazandaran Z. Arabi 47423 (TUH) MH219817; – Dichodon persicus Boiss. Iran, Prov. Hamedan Z. Arabi 47421 (TUH) MH219818; MH243546 Holosteum umbellatum L.* - - - JN589051.1; FJ404909.1 Lepyrodiclis stellarioides Fisch. & C.A.Mey.* - - - KP148941; KP149044 Moenchia erecta (L.) G.Gaertn., B.Mey. & Scherb.* - - - JN589103.1; FJ404926.1 Myosoton aquaticum (L.) Moench Germany F. Schuhwerk 06/357 (M) MH219819; MH243547 Odontostemma glandulosum Benth.* - - - KP148863.1; KP148961.1 Pseudostellaria rupestris (Turcz.) Pax* - - - KX158313.1; KX158424.1 Shivparvatia ciliolata (Edgew. & Hook.f.) Pusalkar & D.K.Singh* - - - KP148859.1; KP148956.1 Stellaria graminea L. Germany A. Mayer s.n. (M) MH219820; MH243548 Stellaria holostea L. Spain D. Podlech 05-1265 (MSB) MH219821; MH243549 DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 223 Results Morphological studies The studied populations of Dichodon show variation in the following characters: growth habit, presence of glandular hairs, petal length and apical incision, curvature of capsule teeth and pedicles at fruiting stage, and seed size. We observed significant variation correlated with geographical patterns never mentioned previously. The specimens from Azerbaijan province in Iran are erect, have petals slightly longer than sepals and notched at the apex, the inflorescences are covered with glandular hairs, and capsule teeth are reclined horizontally (or patent). These differences made them morphologically somewhat similar to the specimens collected from Damavand Mountain (the highest peak in Iran) at an altitude of 3400 m. The specimens from Hamedan province were perennial and glabrous plants found in small patches, with petals as long as sepals, notched at the apex, pedicels semi-deflexed at fruiting stage, and capsule teeth circinate. The specimens collected in Touchal, Azadbar and Damavand (all stations in Alborz mountain range in North Iran) at an altitude of about 4200 m were similar to the specimens from Hamedan, but show a remarkable difference in habit (annual vs. perennial) as well as curvature of fruiting pedicels. Important morphological features useful for separation of studied populations of Dichodon are presented in Table 2. Photographs of the representative samples are shown in Fig. 1. TABLE 2. Morphological comparison among the studied Dichodon taxa. D. alborzensis D. cerastoides D. viscidus D. kotschyi D. persicus Habit annual/biennial decumbent with aggregate of basal leaves perennial, caespitose annual, decumbent annual, erect without aggregate of basal leaves perennial, caespitose Leaves spatulate oblong lanceolate linear spatulate Inflorescence reflexed pedicel when fruiting, glabrous reflexed pedicel when fruiting, glabrous or sometimes glandular hairy erect pedicel when fruiting, glandular erect pedicel when fruiting, glandular hairy semireflexed pedicel when fruiting, glabrous Petals slightly exceeding sepals longer than sepals 2× longer than sepals slightly exceeding sepals/as long as sepals as long as sepals Capsule teeth circinate circinate erect reclined horizontally, circinate outwardly patent coiled Seed (mm) 0.80‒1.05 0.89‒1.08 0.63‒0.65 0.69‒0.83 Geographical distribution N Iran (Alborz mts.), N Iran, Damavand, 3700 m 3450 m ± cosmopolitan East Mediterranean (mostly introduced), to N-Iran, 1800‒ 3400 m 900 m 0.80‒0.96 W Iran, ca. 2500 m Phylogenetic analyses The results of phylogenetic analyses employing both nuclear (ITS) and plastid markers (rps16) DNA sequences were similar but the relationships within the group were more resolved in the ITS phylogeny compared to that of rps16 (Appendix I–II). For the combined dataset, maximum parsimony search was reached at the initial Maxtrees of 20000 (L= 818, CI= 0.6883, RI=0.7335). Tree topologies resulting from MP and BI were congruent. The results of the BI of the combined dataset are discussed here (Fig. 2) and other trees are presented in Appendix I–II. The monophyly of Dichodon is strongly supported (100% BS; 1.00 PP) with Holosteum sister to this clade though with low support (BS=55%, PP=0.52). Dichodon viscidus represents the most basal clade in the genus followed by D. kotschyi (Boissier 1867: 715) Ikonnikov (1973: 142), D. cerastoides, D. persicus (Boissier 1843: 54) Ikonnikov (1973: 142) and the new species, D. alborzensis Arabi & Zarre (see under taxonomic conclusion), respectively. 224 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. FIGURE 1. Representatives of three Dichodon spp. from Iran in different locations. A–B: D. kotschyi in Prov. Azerbaijan, 2450 m; C–D: D. kotschyi in Prov. Mazandaran, 3450 m; E–F: D. alborzensis in Prov. Mazandaran, 4200 m; G–H: D. alborzensis in Prov. Alborz, 2500 m; I–J: D. alborzensis Tehran, 3700 m; K–L: D. persicus in Prov. Hamedan, 2500 m. DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 225 FIGURE 2. (A) Majority rule consensus tree inferred from Bayesian analysis of combined dataset of nrDNA ITS and cpDNA rps16 sequences showing the phylogenetic relationships in Dichodon and its placement in tribe Alsineae (Caryophyllaceae). Posterior probability (PP—above) and bootstrap support (BS—below) values are reported at the nodes. (B) Morphological characters reconstructed are shown by numbers and squares are explained in the legend. 226 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. Seed micromorphology Different populations of Dichodon spp. showed variation in seed size. The smallest seeds belonged to the European representatives of Dichodon viscidus (0.63‒0.69 mm), while the largest are observed in D. cerastoides (0.89‒1.08 mm; reported recently by Arabi et al. 2017). All studied samples of Dichodon showed the typical verrucate type of seed surface ornamentation. In this type, the testa cells are stellate and deeply armed and bear central projections (Fig. 3). The outer periclinal walls were convex. Discussion The phylogenetic position of Cerastium subg. Dichodon in relation to Cerastium subg. Cerastium and other genera of Alsineae was investigated in previous molecular phylogenetic studies (Scheen et al. 2004, Greenberg & Donoghue 2011), but based on a limited number of representative accessions. The result of the present study using a rich sampling of Dichodon also confirms the placement of this genus outside of Cerastium (Fig. 2A). According to these findings, Holosteum rather than Cerastium should be considered as the closest relative of Dichodon, a conclusion also suggested by Greenberg & Donoghue (2011). Therefore, in agreement with some previous studies (Scheen et al. 2004, Greenberg & Donoghue 2011, Hernández-Ledesma et al. 2015), we reject considering Dichodon as a subgenus or section of Cerastium. Seed morphology also indicates a unique pattern of testa sculpturing in Dichodon. All members of Dichodon show a verrucate type (Fig. 3) of testa sculpturing absent in Holosteum and Cerastium which are rather tuberculate or colliculate. Holosteum is also distinguished from its close relatives by its unique shield shaped seeds (McNeill 1962, Arabi et al. 2017)., Variation of testa sculpturing in Cerastium is remarkable and can be correlated to infrageneric groups (sections) (Arabi et al. 2017), but these do not overlap with the type observed in Dichodon. Interspecific relationships and delimitation of species or subspecific taxa were also addressed here. Despite the precise taxonomic studies previously done on species borders within Dichodon (Ikonnikov 1973, 1976), there are still uncertainties, making the identification of several populations in the genus problematic. Here we tried to solve these issues through detailed examination of herbarium materials, literature, and field observations with a special focus on Iran, a country where most Dichodon species occur. Patterns of changes for some important morphological characters are presented in Fig. 2B. The morphological studies on populations from different areas indicated that D. viscidus is easily recognizable by its annual/biennial habit. In addition, it is characterized by lanceolate leaves, glandular-pilose, lanceolate sepals, petals 1.5‒2 times longer than sepals, and capsule teeth erect (Cullen 1967, Möschl 1988). Although D. kotschyi is defined to be closely related to D. viscidus, it is distinguished from the latter by spatulate leaves and petals as long as or slightly longer than sepals (less than 1.5 times longer than sepals), slightly bifid or notched, horizontally reclined capsule teeth and larger seeds. Our populations from Azerbaijan province and the area around Damavand Mountain (3400 m a.s.l.) fit well with the type of D. kotschyi and its description. On the other hand the samples of D. schischkinii (Grossheim 1950: 9) Ikonnikov (1973: 142) match morphologically well with those of D. kotschyi. Therefore, we suggest extending the distribution pattern of D. kotschyi from E-Turkey to NW-Iran and the Caucasus region to include D. schischkinii. In our molecular phylogenetic analyses, the representative populations of D. kotschyi formed a distinct clade with BS 100% and PP 1.00. We included three populations of Dichodon from higher altitudes (about 4200 m a.s.l.) of Alborz Mountain ranges of North Iran in our molecular phylogenetic analyses. These plants are annual or biennial in habit and differ from the typical representatives of D. viscidus in length and incision of petals, stem branched from the base, the shape of capsule teeth and curvature of the pedicel while fruiting (see below under description of D. alborzensis). These populations can also be compared with D. persicus for which our population from Hamedan province matches best. These plants share similar features except their habit. From a genetic point of view, all populations collected from Alborz mountains that are regarded here as D. alborzensis (see under taxonomic conclusion), share an 18bp long insertion in rps16 marker which is missing in all other species of Dichodon. Dichodon cerastoides as a perennial species subtending this clade (Fig. 2), is characterized by its growth form (forming dense mats), presence of glandular trichomes on stems or sometimes on sepals, and considerable incision of petals. DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 227 FIGURE 3. SEM micrographs of seeds of selected taxa of Dichodon distributed in Iran. SEM micrographs of Dichodon cerastoides seeds were published recently in Arabi et al. (2017). A–B: D. kotschyi; C–D: D. alborzensis; E–F: D. persicus; G–H: D. viscidus. 228 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. Conclusion The phylogenetic analyses along with the morphological evidence indicate that Dichodon is monophyletic, and keeping it as a separate genus in tribe Alsineae is reasonable. Based on the result of the present study, we increase the number of recognized species of Dichodon to seven; with five taxa distributed in Iran. Dichodon (Bartling ex Reichenbach) Reichenbach, Deut. Bot. Herb.-Buch 205. 1841 ≡ Cerastium subg. Dichodon (Bartling ex Reichenbach 1832: 785) Fenzl (1842: 396) ≡ Cerastium sect. Dichodon (Bartling ex Reichenbach 1832: 785) Grisebach (1843: 207) ≡ Provancheria B.Boivin (1966: 644). Lectotype (designated by Ikonnikov 1973): Dichodon dubius (Bastard 1812: 24) Ikonnikov (1973: 141) [synonym of D. viscidus (M.Bieb.) Holub (1974:273)]. Description:—Annual, biennial or perennial herbs, glabrous or often glandular hairy in the upper parts. Roots slender, sometimes rhizomatous, or rooting at nodes. Stems erect or decumbent. Leaves lanceolate or spatulate, mostly succulent. The lowest bracts herbaceous, then gradually decreasing to 2‒5 mm, without scarious margins. Inflorescence few- to many-flowered, in terminal or sometimes axillary cymes. Pedicels erect or reflexed in fruit. Sepals ovate to lanceolate, distinct, inner sepals with wide scarious margins, the outer ones without or with narrow scarious margins. Petals 5(‒8) white, slightly to deeply notched. Styles 3 (rarely 4 or 5). Stamens 5‒10. Capsule oblongoid to cylindrical, opening by teeth twice as many as styles, as long as or slightly exceeding the sepals, teeth reclined, patent or circinately revolute. Seeds many, greyish yellow, verrucate. 2n = 36, 38. Diagnostic key to the species of Dichodon in Iran: 1. 2. 3. 4. - Axillary inflorescences in axil of some leaves present; basal rosettes absent ....................................................................................2 Axillary inflorescences absent; with aggregation of basal leaves at stem base ................................................................................3 Erect plants; stems single or dichotomously branched at the base .................................................................................... D. kotschyi Decumbent plants; stems richly branched at the base ........................................................................................................D. viscidus Annual or biennial plants.............................................................................................................................................. D. alborzensis Perennial plants ..................................................................................................................................................................................4 Petals longer than sepals, deeply incised; sterile axillary shoots present ......................................................................D. cerastoides Petals equal to or shorter than sepals, shallowly incised; sterile axillary shoots absent ................................................... D. persicus Species richness in Iran:—There are five species of Dichodon in Iran distributed mostly in wet meadows at higher altitudes (more than 2500 m). Based on molecular, and morphological studies, the following new species is here described: Dichodon alborzensis Arabi & Zarre, sp. nov. (Fig. 1: E–J) Type:—IRAN. Tehran: North Tehran, Touchal mountains, 3700 m, 15 July 2016, Z. Arabi 47422 (holotype TUH-SZ47422!, isotype M!). Diagnosis:—Dichodon alborzensis is closely related to D. persicus and D. cerastoides. These two latter species form separate small patches, while D. alborzensis plants are annual or biennial herbs growing as widely scattered individuals, not occurring in clumps. Moreover, D. alborzensis differs from D. cerastoides by the absence of sterile shoots and shallowly incised petals which are equal or slightly exceeding the sepals. Description:—Annual or biennial plants, glabrous throughout. Taproots slender with fibrous-like lateral roots attached. Stems with rosette of basal leaves, lower internodes short. Leaves succulent, basal ones spatulate, cauline ones lanceolate. Inflorescence terminal, 3-flowered (rarely 1-flowered), lax. Styles 3(4). Bracts similar to leaves, without scarious margins. Pedicels long and deflexed when fruiting. Petals 5, white, slightly longer than sepals, shallowly notched. Stamens 5 or 10. Capsules cylindrical, with 6(‒8) circinate teeth. Seeds many, ovate, 0.80‒0.95 mm, verrucate on surface. Etymology:—“alborzensis” came from Alborz, a mountain range in North Iran where the new species has been discovered at three locations. DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 229 Taxonomic notes:—The type specimen of Dichodon alborzensis was collected in the Touchal Mountains in North Tehran. Two other populations of this taxon were found at Azadbar and Damavand at about 4200 m a.s.l. (Fig. 4). In the Damavand area, we recognized three populations of Dichodon representing three species, i.e. D. cerastoides, D. kotschyi and D. alborzensis. The annual/biennial plants from higher elevations of Damavand were morphologically different from the annual ones observed at the lower elevation previously determined as Cerastium schischkinii Grossheim (1950: 9). Our detailed examination of C. schischkinii confirms major differences between it and D. alborzensis. The specimens distributed in Azadbar and Damavand by earlier workers (cited in Möschl 1988) have been determined as C. viscidus in Flora Iranica (Möschl 1988) which is inconsistent with the result of the present study. FIGURE 4. Distribution map of Dichodon spp. in Iran. (■) D. alborzensis, (●) D. kotschyi and (▲) D. persicus. Dichodon cerastoides and D. viscidus are widespread in West and North Iran. Conservation status:—Few populations (each with less than 100 individuals, two patches in Demavand, and one in each Azadbar and Touchal) of Dichodon alborzensis were found in meadows close to wet soils in field. We assessed D. alborzensis as endangered (EN) (IUCN 2017) because the Alborz Mountains are a popular tourist area close to Iran’s capital (Tehran) and is often visited by local people on weekends. In addition, the annual precipitation in this area has decreased significantly in the last few years and the area available for wet meadows is shrinking drastically. Paratypes:—IRAN. Mazandaran: Polour, Damavand mountain, southern slopes, 4200 m, 29 July 2015, Arabi 47424 (TUH!); Mazandaran: Alborz mountain range, Azadbar, 2500 m, 17 July 2016, Arabi 47420 (TUH!). New record for Iran:—Dichodon kotschyi was found for the first time in Iran. A description of the species based on the Iranian population follows: 230 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. Dichodon kotschyi (Boissier) Ikonnikov, Novosti Sist. Vyssh. Rast. 10: 142. 1973 ≡ Cerastium kotschyi Boissier (1867: 715) ≡ Arenaria kotschyi (Boissier 1867: 715) Shinners (1962: 50) ≡ Cerastium viscidus var. kotschyi (Boissier 1867: 715) Mouterde (1966: 477) (Fig. 1A–B). Type (lectotype, designated here):—ANTILIBANON [SYRIA]: circa Zebdaine prope Damascum, in madidis as fontes supra Bludan, alt. 5000’, 14 June 1855, Kotschy 128 [G!, isolectotypes: BM, BM000595327! (https://plants.jstor.org/stable/history/10.5555/al.ap. specimen.bm000595327), MPU, MPU013768! (https://plants.jstor.org/stable/10.5555/al.ap.specimen.mpu013768), K, K000723534! (http://apps.kew.org/herbcat/getImage.do?imageBarcode=K000723534, as C. anomalum Schrank (1795: 73)]. = Dichodon schischkinii (Grossheim 1950: 9) Ikonnikov (1973: 142) ≡ Cerastium schischkinii (Grossheim 1950: 9), syn. nov. Type (lectotype, designated here):—AZERBAJDZHAN [Azerbaijan]: Republica Autonoma Nachitschevan, distr. Schachbuz, in trajecto Bitschenach, ca. 2500 m, in pascuis, 16 June 1947, Grossheim, Iljinskaia & Kirpitcznikov s.n. (LE!, barcode LE 01042957). Description:—Annual plants, erect, covered with glandular hairs in upper parts. Taproots slender. Stems single, sometimes branched from the base dichotomously, lacking the aggregation of basal leaves. Leaves linear to narrowly lanceolate, light green, non-succulent. Inflorescences 3 to many-flowered, axillary inflorescences sometimes present. Bracts similar to the leaves, without scarious margins. Pedicels usually short, the lowest ones 1.5–2.5 times longer than sepals, the others equal to or shorter than sepals, congested to some extent, and erect. Petals white, slightly exceeding sepals, not deeply notched. Styles 3(4). Stamens 10. Sepals lanceolate, with wide scarious margins, glandular, purpletinged. Capsules cylindrical, mostly as long as sepals with short horizontally reclined or patent teeth. Seeds many, ovate, greyish yellow, 0.7–0.8 mm diam., verrucate on surface. Typification of Cerastium kotschyi:—Four sheets numbered with “128” and collected by Kotschy “prope Bludan”, as reporetd in the protologue, were found at BM, G-BOIS, K and MPU. These specimens are syntypes (Art. 9.5 of ICN), and as a consequence, a lectotypification is necessary (Art. 9.1 of ICN). G-BOIS specimen is here designated as the lectotype, the other ones at BM, K, and MPU are isolectotypes. Typification of Cerastium schischkinii:—The citation of the type in the protologue (Grossheim 1950: 10) runs as follows: “Azerbajdzhan, respublica autonoma Nachitschevan, distr. Schachbuz, in trajecto Bitschenach ca. 2500 m, in pascuis 16 VI 1947, fl., fr., A. Grossheim, I. Iljinskaja et M. Kirpitcznikov. In Herb. Inst. Bot. nom. ac. V. L. Komarovii Ac. Sc. URSS in Leningrad conservatur”. No specimen, however, with the label in perfect agreement with the protologue was found in the collections of LE. Deposited in LE there are 6 sheets labelled as: “Azerbaijan, Nakhichevan Autonomous Republic, Shakhbuz District, slopes of Batabat-dag Mt. above Bichenakh pass, 2350–2450 m a.s.l., alpine pastures, Grossheim, Iljinskaja, Kirpicznikov” (originally in Russian) are available in LE, 5 of them with the same collection date as in the protologue (16 June 1947), and one sheet without any date. All the specimens are determined by Grossheim as “Cerastium schischkinii sp. nova” in August 1948 and tagged as “Specimen authenticum” with a handwritten note “Cotypus!” by Grossheim. In addition, two sheets labelled as “Azerbaijan, Nakhichevan Autonomous Republic, Bichenakh village, ca. 1800 m a.s.l., forest limits, wet depression, 28 V 1947, Grossheim, Iljinskaja, Kirpicznikov” are deposited in the herbarium LE. These are also determined by Grossheim as “Cerastium schischkinii sp. nova” in August 1948, and one of them is tagged as “Specimen authenticum” with the handwritten “Typus!” by Grossheim. We consider all the cited specimens as original material of the name, and choose the lectotype from among the ones collected on 16 June 1947, as their labels agree with the protologue in more detail (locality, date, habitat). Taxonomic notes:—Dichodon kotschyi can be distinguished from D. viscidus by its non-succulent, linear to narrowly linear leaves, single to dichotomous stems, petals as long as sepals or slightly longer than sepals, and capsules mostly as long as sepals with patent capsule teeth. These characters and distribution of the specimens in lower elevation of Damavand correspond well with Grossheim’s description of Cerastium schischkinii, but the result of the phylogenetic analysis together with morphological evidence confirm C. schischkinii as a synonym of D. kotschyi. Conservation status:—Dichodon kotschyi has a wide distribution range starting from high altitudes (>2500 m) western from Syria, Turkey, Caucasus region and northwest to north Iran. Similar to D. alborzensis it is restricted to wet meadows that are subjected to lower precipitation leading to reduced individuals and populations of this species. In Iran we found about 100 individuals of this species in each locality in Prov. E Azerbaijan and Prov. Tehran, each locality with several patches (ca. 20 individuals in each patch). This species can be classified as the category Near Threatened (NT) according to the IUCN system (IUCN 2017). Selected specimens:—IRAN. Prov. East Azerbaijan: Tabriz, Almalou Gul, 2450 m, N 46.631944 E 37.664722, 16 August 2016, Arabi 47419 (TUH); Prov. Tehran: North Tehran, Mt. Damavand, southern slopes, 3450 m, ‎02 July 2016, Arabi 47423 (TUH). DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 231 Acknowledgements This paper presents some results of the project, supported partly by the Iran National Science Foundation (INSF, grant number 96003422). ZA and FG are grateful to the University of Kharazmi for supporting their works. We are grateful to Directors and Curators of the herbaria B, M, MSB, TUH, W, and WU for their generous assistance, providing plant materials and photographs for this study. L. Gautier (Head Curator—Phanerogams, G) assisted us through providing the image of the type of D. kotschyi in G, which is much appreciated. SZ also appreciates financial supports provided by Alexander Humboldt Stiftung (Germany) as well as University of Tehran. We are also thankful to T. Ernst (Munich) for laboratory assistance. IS’s study was carried out within the framework of the institutional research project no. АААА-А18-118030590100-0 of the Komarov Botanical Institute of the Russian Academy of Sciences. References Amini, E., Zarre, S. & Assadi, M. (2011) Seed micro-morphology and its systematic significance in Gypsophila (Caryophyllaceae) and allied genera. Nordic Journal of Botany 29: 660–669. https://doi.org/10.1111/j.1756-1051.2011.01208.x Arabi, Z., Ghahremaninejad, F., Rabeler, R.K., Heubl, G. & Zarre, S. (2017) Seed micromorphology and its systematic significance in tribe Alsineae (Caryophyllaceae). Flora 234: 41–59. https://doi.org/10.1016/j.flora.2017.07.004 Barthlott, W. (1981) Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects. Nordic Journal of Botany 1: 345–355. https://doi.org/10.1111/j.1756-1051.1981.tb00704.x Bastard, T. (1812) Supplément à l’Essai sur la Flore du département de Maine-et-Loire. Impr. de L. Pavie, Angers, XII + 58 pp. Baumgarten, J.Ch.G. (1816) Enumeratio Stirpium Magno Transsilvaniae Principatui praeprimis indigenarum in usum nostratum botanophilorum conscripta inque ordinem sexuali-naturalem concinnata. 3. Libraria Camesinae, Vindobonae, 428 pp. Bittrich, V. (1993) Caryophyllaceae. In: Kubitzki, K. (Ed.) Families and genera of vascular plants. Springer Verlag, Berlin, pp. 206– 236. https://doi.org/10.1007/978-3-662-02899-5_21 Boissier, P.E. (1843) Diagnoses Plantarum Orientalium novarum, vol. 1. Apud B. Hermann, Lipsiae [Leipzig], 76 pp. Boissier, P.E. (1867) Flora Orientalis: sive, Enumeratio plantarum in Oriente a Graecia et Aegypto ad Indiae fines hucusque observatarum, vol. 1. H. Georg, Basileae & Geneva, 1017 pp. Boivin, J.R.B. (1966) Enumération des plantes du Canada. Le Naturaliste Canadien 93 (5): 583–646. Conti, F., Bartolucci, F., Iamonico, D. & Del Guacchio, E. (2014) A new combination in Mcneillia (Caryophyllaceae) for the Italian flora. Phytotaxa 170 (2): 139–140. https://doi.org/10.11646/phytotaxa.170.2.8 Cullen, J. (1967) Cerastium. In: Davis, P.H. (Ed.) Flora of Turkey and the East Aegean Islands, vol. 2. Edinburgh University Press. pp. 73–85. Darriba, D., Taboada, G.L., Doallo, R. & Posada, D. (2012) jModelTest 2: more models, new heuristics and parallel computing. Nature methods 9: 772–772. https://doi.org/10.1038/nmeth.2109 Davis, J.I., Stevenson, D.W., Petersen, G., Seberg, O., Campbell, L.M., Freudenstein, J.V., Goldman, D.H., Hardy, C.R., Michelangeli, F.A. & Simmons, M.P. (2004) A phylogeny of the monocots, as inferred from rbcL and atpA sequence variation, and a comparison of methods for calculating jackknife and bootstrap values. Systematic Botany 29: 467–510. https://doi.org/10.1600/0363644041744365 Dillenberger, M.S. & Kadereit, J.W. (2014) Maximum polyphyly: Multiple origins and delimitation with plesiomorphic characters require a new circumscription of Minuartia (Caryophyllaceae). Taxon 63: 64–88. https://doi.org/10.12705/631.5 Endlicher, S.F.L. (1836–1840) Genera Plantarum II. Apud Fr. Beck Universitatis Bibliopolam, Vindobonae, 1484 pp. Fenzl, E. (1842) Cerastium L. In: Ledebour, C. (Ed.) Flora Rossica, vol. 1. E. Schweizerbart, Stuttgart, pp. 396–416. Fior, S. & Karis, P.O. (2007) Phylogeny, evolution and systematics of Moehringia (Caryophyllaceae) as inferred from molecular and morphological data: A case of homology reassessment. Cladistics 23: 362–372. https://doi.org/10.1111/j.1096-0031.2007.00150.x Greenberg, A.K. & Donoghue, M.J. (2011) Molecular systematics and character evolution in Caryophyllaceae. Taxon 60: 1637–1652. 232 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. Grisebach, A.H.R. (1843) Spicilegium Florae Rumelicae et Bithynicae, vol. 1. Fridericum Vieweg und Sohn, Brunsvigae, 407 pp. Grossheim, A. (1950) Plantarum species novae et criticae e Caucaso. Botanicheskie Materialy Gerbariya Botanicheskogo Instituta Imeni V.L. Komarova Akademii Nauk SSSR 13: 9–10. Guépin, J.P. (1838) Flore du Département de Maine et Loire ed. 2. L. Pavie, Angers, 409 pp. Harbaugh, D.T., Nepokroeff, M., Rabeler, R.K., McNeill, J., Zimmer, E.A. & Wagner, W.L. (2010) A New Lineage-Based Tribal Classification of the Family Caryophyllaceae. International Journal of Plant Sciences 171: 185–198. https://doi.org/10.1086/648993 Hernández-Ledesma, P., Berendsohn, W.G., Borsch, T., Mering, S.V., Akhani, H., Arias, S., Castañeda-Noa, I., Eggli, U., Eriksson, R. & Flores-Olvera, H. Fuentes-Bazán, S., Kadereit, G., Klak, C., Korotkova, N., Nyffeler, R., Ocampo, G., Ochoterena Booth, H., Oxelman, B., Rabeler, R.K., Sánchez, A., Schlumpberger, B.O. & Uotila, P. (2015) A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales. Willdenowia 45: 281–383. https://doi.org/10.3372/wi.45.45301 Holub, J. (1974) New names in Phanerogamae 3. Folia Geobotanica et Phytotaxonomica 9 (3): 261–275. Iamonico, D. (2014) Arenaria tenuifolia versus Arenaria hybrida (Caryophyllaceae): nomenclatural study and taxonomic implications. Phytotaxa 173 (3): 235–240. https://doi.org/10.11646/phytotaxa.173.3.6 Iamonico, D. (2016) Nomenclatural notes on four Linnaean names in Arenaria (Caryophyllaceae). Taxon 65 (3): 610–616. http://dx.doi.org/10.12705/653 Iamonico, D. & Domina, G. (2015) Nomenclatural notes on the Polycarpon tetraphyllum aggregate (Caryophyllaceae). Plant Biosystems 149 (4): 720–727. https://doi.org/10.1080/11263504.2015.1057260 Ikonnikov, S.S. (1973) Notae de Caryophyllaceis, 1. [Notes on Caryophyllaceae, 1. On the genus Dichodon (Bartl.) Reichb.]. Novosti Sistematiki Vysshikh Rastenii 10: 136–142. Ikonnikov, S.S. (1976) Notae de Caryophyllaceis, 3. [Notes on Caryophyllaceae, 3. On the genus Dichodon (Bartl.) Reichb.]. Novosti Sistematiki Vysshikh Rastenii 13: 113–120. IUCN (2017) The Red List of Threatened Species. Version 2017-3. Available from: http://iucnredlist.org (accessed 26 April 2018) Kanwal, D., Abid, R. & Qaiser, M. (2012) The seed atlas of Pakistan-VI. Caryophyllaceae. Pakistan Journal of Botany 44: 407–424. Katoh, K. & Standley, D.M. (2013) MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Molecular Biology and Evolution 30: 772–780. https://doi.org/10.1093/molbev/mst010 Kool, A., Perrigo, A. & Thulin, M. (2012) Bristly versus juicy: Phylogenetic position and taxonomy of Sphaerocoma (Caryophyllaceae). Taxon 61: 67–75. Linnaeus, C. (1753) Species Plantarum, vol. 1. Imprensis Laurentii Salvii, Holmiae, 560 pp. Löve, A. & D. Löve (1976) Nomenclatural notes on arctic plants. Botaniska Notiser 128: 497–523. Maddison, W. & Maddison, D. (2010) Mesquite: a modular system for evolutionary analysis. 2011; Version 2.75. Available from: http:// mesquiteproject. org/mesquite/download/download.html (accessed 26 April 2018) Madhani, H., Rabeler, R.K., Pirani, A., Oxelman, B., Heubl, G. & Zarre, S. (2018) Untangling taxonomic confusion in the carnation tribe (Caryophyllaceae: Caryophylleae) with special focus on generic boundaries. Taxon 63: 83-112. Mahdavi, M., Assadi, M., Fallahian, F.& Nejadsattari, T. (2012) The systematic significance of seed Micro-Morphology in Stellaria L.(Caryophyllaceae) and its closest relatives in Iran. Iranian journal of Botany 18: 302–310. Marschall von Bieberstein, F.A. (1808) Flora taurico-caucasica exhibens stirpes phaenogamas, in Chersoneso Taurica et regionibus caucasicis sponte crescentes, vol. 1. Typis academicis, Charkouiae [Kharkov], 428 pp. McNeill, J. (1962) Taxonomic studies in the Alsinoideae: I. Generic and infra generic groups. Notes from the Royal Botanic Garden, Edinburgh 24: 79–155 McNeill, J., Barrie, F.R., Buck, W.R., Demoulin, V., Greuter, D.L., Hawksworth, D.L., Herendeen, P.S., Knapp, S., Marhold, K., Prado, J., Proud’Homme van Reine, W.F., Smith, J.F. & Wiersema, J.H. (Eds.) (2012) International Code of Nomenclature for algae, fungi and plants (Melbourne Code): Adopted by the Eighteenth International Botanical Congress, Melbourne, Australia, July 2011. Regnum Vegetabile 154: 1–274. Miller, M.A., Pfeiffer, W. & Schwartz, T. (2011) The CIPRES science gateway: a community resource for phylogenetic analyses. Proceedings of the 2011 TeraGrid Conference: extreme digital discovery. ACM, p. 41. https://doi.org/10.1145/2016741.2016785 Minuto, L., Fior, S., Roccotiello, E. & Casazza, G. (2006) Seed morphology in Moehringia L. and its taxonomic significance in comparative studies within the Caryophyllaceae. Plant Systematics and Evolution 262: 189–208. https://doi.org/10.1007/s00606-006-0458-1 Moore, A.J. & Dillenberger, M.S. (2017) A conspectus of the genus Cherleria (Minuartia s.l., Caryophyllaceae). Willdenowia 47 (1): DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 233 5–14. https://doi.org/10.3372/wi.47.47101 Möschl, W. (1988) Cerastium L. In: Rechinger, K.H. (Ed.) Flora Iranica, vol. 163. Akademische Druck- u. Verlagsanstalt, Graz, pp. 85–108. Mouterde, P. (1966) Nouvelle flore du Liban et de la Syrie. Éditions de l‘Impr. Catholique, Beirut, 160 pp. Oxelman, B., Lidén, M. & Berglund, D. (1997) Chloroplast rps16 intron phylogeny of the tribe Sileneae (Caryophyllaceae). Plant Systematic and Evolution 206: 393–410. https://doi.org/10.1007/BF00987959 Pax, F.A. (1934) Die Natürlichen Pflanzenfamilien. W. Engelmann, Leipzig, 318 pp. Petri, A. & Oxelman, B. (2011) Phylogenetic relationships within Silene (Caryophyllaceae) section Physolychnis. Taxon 60: 953–968. Pirani, A., Zarre, S., Pfeil, B.E., Bertrand, Y.J., Assadi, M. & Oxelman, B. (2014) Molecular phylogeny of Acanthophyllum (Caryophyllaceae: Caryophylleae), with emphasis on infrageneric classification. Taxon 63: 592–607. https://doi.org/10.12705/633.39 Rambaut, A. (2012) FigTree v. 1.4.0. Available from: http://tree.bio.ed.ac.uk/software/figtree (accessed 26 April 2018) Rambaut, A. & Drummond, A.J. (2007) Tracer v. 1.5. Available from: http://beast.bio.ed.ac.uk/Tracer (accessed 26 April 2018) Reichenbach, H.G.L. (1832) Flora Germanica Excursoria. Carolum Cnobloch, Leipzig, 878 pp. Reichenbach, H.G.L. (1841a) Der Deutsche Botaniker. Erster Band. Das Herbarienbuch. Arnoldische Buchhandlung, Dresden and Leipzig, 236 pp. Reichenbach, H.G.L. (1841b) Icones Florae Germanicae et Helveticae, vol. 5. Sumptibus Friderici Hofmeister Lipsiae [Leipzig], 38 pp. Ronquist, F., Teslenko, M., Van Der Mark, P., Ayres, D.L., Darling, A., Höhna, S., Larget, B., Liu, L., Suchard, M.A. & Huelsenbeck, J.P. (2012) MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61: 539–542. https://doi.org/10.1093/sysbio/sys029 Scheen, A.C., Brochmann, C., Brysting, A.K., Elven, R., Morris, A., Soltis, D.E., Soltis, P.S. & Albert, V.A. (2004) Northern hemisphere biogeography of Cerastium (Caryophyllaceae): insights from phylogenetic analysis of noncoding plastidnucleotide sequences. American Journal of Botany 91: 943–952. https://doi.org/10.3732/ajb.91.6.943 Schischkin, B.K. (1936) Cerastium L. In: Komarov, V.L. (Ed.) Flora of the U.S.S.R., vol. 6. Izdatel’stvo Akademii Nauk SSSR, MoskvaLeningrad, pp. 430–466. [in Russian, and English translation 1970 by Scientific Translation, Jerusalem, pp. 330–359] Seringe, N.C. (1824) Cerastium L. In: Candolle, A.P. de (Ed.) Prodromus Systematis Naturalis Regni Vegetabilis, vol. 1. Treuttel & Wertz, Paris. pp. 414–421. Shinners, L.H. (1962) New names in Arenaria (Caryophyllaceae). Sida 1: 49–52. Stearn, W.T. (1983) Botanical Latin. revised. David & Charles, Newton Abbot, London and North Pomfret, Vermont, 566 pp. Swofford, D.L. (2003) PAUP*: phylogenetic analysis using parsimony, version 4.0 b10. The Plant List (2013) Dichodon. The Plant List. A. working list of all plant species. Available from: www.theplantlist.org (accessed 09 March 2018) Thiers, B. (2018+) [Continuously updated] Index Herbariorum: A global directory of public herbaria and associated staff. Available from: http://sweetgum.nybg. org/science/ih/ (accessed 26 April 2018) Thuillier, J.L. (1799) Flore des Environs de Paris, ou Distribution Methodique des Plantes qui y croissent naturellement. Chez l’auteur, H.L. Perronneau, Paris, 550 pp. Vargas, P., Baldwin, B.G. & Constance, L. (1998) Nuclear ribosomal DNA evidence for a western North American origin of Hawaiian and South American species of Sanicula (Apiaceae). Proceedings of the National Academy of Sciences of the United States of America 95: 235–240. https://doi.org/10.1073/pnas.95.1.235 Villars, D. (1789) Histoire des Plantes de Dauphiné. Chez l’auteur, Grenoble, 467 pp. White, T.J., Bruns, T., Lee, S. & Taylor, J. (1990) Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis, M.A., Gelfand, D.H., Sninsky, J.J. & White, T.J. (Eds.) PCR protocols: A guide to methods and applications. Academic Press, San Diego, pp. 315–322. https://doi.org/10.1016/B978-0-12-372180-8.50042-1 Williams, F.N. (1895) On the genus Arenaria Linn. Bulletin de l’Herbier Boissier 3: 593–603. Wofford, B.E. (1981) External seed morphology of Arenaria (Caryophyllaceae) of the southeastern United States. Systematic Botany 6: 126–135. https://doi.org/10.2307/2418543 Yao, G. (2016) Dichodon parvipetalus, a new combination for the Chinese Caryophyllaceae. PhytoKeys 69: 129–130. https://doi.org/10.3897/phytokeys.69.8494 234 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL. Appendix I. Majority rule consensus tree obtained from Bayesian analysis of nrDNA ITS sequences showing the phylogenetic relationships in Dichodon and its placement in tribe Alsineae (Caryophyllaceae). Posterior probability (PP) and bootstrap support (BS) values are shown near statistically supported nodes. DICHODON (CARYOPHYLLACEAE: TRIBE ALSINEAE) Phytotaxa 360 (3) © 2018 Magnolia Press • 235 Appendix II. Majority rule consensus tree obtained from Bayesian analysis of cpDNA rps16 sequences showing the phylogenetic relationships in Dichodon and its placement in tribe Alsineae (Caryophyllaceae). Posterior probability (PP) and bootstrap support (BS) values are shown near statistically supported nodes. 236 • Phytotaxa 360 (3) © 2018 Magnolia Press ARABI ET AL.