Nomenclatural changes in Lithospermum (Boraginaceae) and related taxa following a reassessment of phylogenetic relationships
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- Cohen, J.I. & Davis, J.I. Brittonia (2009) 61: 101. doi:10.1007/s12228-009-9082-z
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Lithospermum (Boraginaceae) comprises approximately 40 species in both the Old and New Worlds, with a center of diversity in the southwestern United States and Mexico. Using ten cpDNA regions, a phylogeny of Lithospermum and related taxa was reconstructed. Lithospermum (including New World and Old World species) and related New World members of Lithospermeae form a monophyletic group, with Macromeria, Onosmodium, Nomosa, Lasiarrhenum, and Psilolaemus nested among species of Lithospermum. New World Lithospermeae also is a monophyletic group, with Eurasian species of Lithospermum sister to this group. Because Lithospermum is not monophyletic without the inclusion of the other New World genera, species from these genera are transferred to Lithospermum, and appropriate nomenclatural changes are made. New combinations are Lithospermum album, Lithospermum barbigerum, Lithospermum dodrantale, Lithospermum exsertum, Lithospermum helleri, Lithospemum leonotis, Lithospermum notatum, Lithospermum oaxacanum, Lithospermum pinetorum, Lithospermum rosei, Lithospermum trinverium, and Lithospermum unicum; new names are Lithospermum chiapense, Lithospermum johnstonii, Lithospermum macromeria, Lithospermum onosmodium, Lithospermum rzedowskii, and Lithospermum turneri.
The genus Lithospermum L. (Boraginaceae) comprises approximately 40 species (Johnston, 1954a). Although it has a cosmopolitan distribution, most species of the genus occur in the New World, from Canada southward to Peru, with a center of diversity in Mexico and the southwestern United States. Lithospermum and the tribe to which it belongs, Lithospermeae Dumort., were revised by Ivan Johnston in a series of papers from 1952 to 1954 (1952, 1953a, b, 1954a, b). In these papers, Johnston recognized new species within the genus, described new genera, and proposed hypotheses concerning evolutionary relationships within the tribe (1952, 1954a, b). A recent phylogeny of Boraginaceae (Langstrom & Chase, 2002) reconstructs Lithospermeae as monophyletic, but resolution is lacking within the tribe and no New World members of Lithospermeae were included in the analysis; therefore, Johnston’s hypothesis that all six genera of Lithospermeae endemic to the New World (i.e., all New World genera of the tribe other than Lithospermum) are closely related to Lithospermum (Johnston, 1954a) has yet to be tested (but see Thomas et al., 2008). This group includes Macromeria D. Don, Onosmodium Michx., Lasiarrhenum I. M. Johnst., Nomosa I. M. Johnst., Psilolaemus I. M. Johnst., and Perittostema I. M. Johnst. Species of these genera occur from Canada to Guatemala, and as with Lithospermum, the center of diversity for the group is in Mexico. Only two of these genera, Macromeria and Onosmodium, include more than one species; Macromeria includes 11 species and Onosmodium includes seven. Johnston’s generic demarcations within New World Lithospermeae are primarily based on floral characters, such as exserted vs. included anthers; flattened vs. cylindrical filaments; and campanulate, urceolate, or long funnelform vs. salverform or funnelform corolla shapes (Johnston, 1954a, b). However, phylogenetic analyses (Cohen, 2007) suggest that the genera recognized on the basis of these floral features are not monophyletic.
Lithospermum and other New World members of Lithospermeae share characteristic erect, smooth to slightly dimpled, white, lustrous nutlets with basal attachment, and all have three-celled glands inside the corollas, except for ca. 12 taxa in which glands, presumably, have been lost or modified. Closely related genera of Lithospermeae that share these features, such as Buglossoides Moench and Lithodora Griseb. (Thomas et al., 2008), have blue or purple corollas, but these corolla colors do not occur in Lithospermum or other New World members of Lithospermeae.
The taxonomic history of Lithospermum is complex, and the complexity arises, in part, from treatments of the genus in the 1800s. For example, in Plantae e Familia Asperifoliarum Nuciferae (1818), Lehmann circumscribed a broadly inclusive Lithospermum, which included species currently placed in Lithospermum (Johnston, 1954a) as well as species currently included in other genera, such as Mertensia Roth, Buglossoides, Arnebia Forssk., and Lithodora. A later taxonomic treatment of Lithospermum in the Prodromus Systematis Naturalis Regni Vegetabilis by A. P. de Candolle (1846) was, like Lehmann’s treatment, quite inclusive; however, unlike Lehmann, de Candolle divided the genus into three sections. One section, Eulithospermum DC. included only species currently included in Lithospermum (with one exception, L. chinensis Hook. and Arn., which is a synonym of Heliotropium strigosum Willd. [Zhu et al., 1995]). The other two sections in the treatment, Rhytispermum Link and Margarospermum Rchb. f., included species that are often included in other genera, such as Buglossoides, Lithodora, Neatostema I. M. Johnst., and Moltkia Lehm.
Although both Lehmann and de Candolle recognized a large, inclusive Lithospermum, they also recognized two endemic New World genera, Macromeria and Onosmodium (as Purshia Lehm. [Lehmann, 1818], non Purshia DC. ex Poir. [Rosacaeae]). Species from these two genera have only rarely been included in Lithospermum (e.g., Muhlenberg, 1813). This treatment of species in the New World differs from that of many species in the Old World in which it has been common to include species from putatively related genera of Lithospermeae, such as Buglossoides, Lithodora, and Neatostema, in Lithospermum (see Johnston, 1953a [but see Johnston, 1954a, b for taxonomic changes], Flora Iranica [Rechinger, 1967], and Flora of China [Zhu et al., 1995]).
At present, the most widely accepted taxonomic system for the genus derives from Johnston’s revisionary efforts on the genus and tribe during the 1950s, but that treatment also contributed additional complexity to the group’s taxonomy. Johnston placed Arnebia and Echioides Fabr. in Lithospermum in 1952, but two years later he removed them, noting differences in stamens and pollen. Also, he placed some newly described species in Lithospermum in 1953, and transferred them to Arnebia the following year. In his 1952 revision of Lithospermum, Johnston recognized the difficulty of dividing Lithospermum into smaller groups, stating that “The genus has great internal coherence. It is exasperatingly lacking in lines of cleavage” (1952, p. 300).
Taxonomic questions regarding generic boundaries of Lithospermum still arise, as seen in the treatment of Boraginaceae in the Flora of China (Zhu et al., 1995), in which Lithospermum is circumscribed as including species often placed in Buglossoides. Treating Lithospermum in this broad sense is common in Old World literature; however, Buglossoides is not monophyletic (cf. Langstrom & Chase, 2002; Cohen, unpublished data) and may not be sister to Lithospermum.
A recent taxonomic study of Lithospermum (Ralston, 1993) included a phylogenetic analysis of the genus utilizing a total of twenty morphological, palynological, karyological, and chemical characters. This analysis provided support for the recognition of several species groups, but did not resolve relationships among these groups. Recent work on other taxa of New World Lithospermeae includes Turner’s synopses of Macromeria (1994a), Onosmodium (1995), and Lasiarrhenum (1994b), and Boyd’s (2003) phylogeny of Macromeria based on morphological characters.
The present study was undertaken to examine the phylogenetic relationships among species of Lithospermum and other elements of New World Lithospermeae, with two of the goals being to determine whether the non-monotypic genera Lithospermum, Macromeria, and Onosmodium constitute monophyletic groups and to reevaluate the taxonomy of New World Lithospermeae.
Materials and methods
List of taxa included in analyses along with collection or source data and Genbank numbers.
Alkanna tuberculata Greuter
Natl. Bot. Gard. Belgium
Buglossoides arvense (L.) I. M. Johnst.
Natl. Bot. Gard. Belgium
Echium vulgare L.
J. Cohen 212
Lithodora diffU.S.A. (Lag.) I. M. Johnst.
M. Chase 6063
Onosma stellulata Waldst. & Kit.
Natl. Bot. Gard. Belgium
Lasiarrhenum trinervium (Lehm.) I. M. Johnst
J. Cohen 228
Lithospermum californicum A. Gray
J. Cohen 43
Lithospermum canescens Lehm.
J. Cohen & S. Straub 12
Lithospermum caroliniense MacMill.
J. Cohen 11
Lithospermum cobrense Greene
J. Cohen 78
Lithospermum erythrorhizon Siebold and Zucc.
J. Cohen 173
Lithospermum multiflorum A. Gray
J. Cohen 57
Lithospermum nelsonii Greenm.
J. Cohen 184
Nuevo León, Mexico
Lithospermum obovatum J. F. Macbr.
J. Cohen 208
Lithospermum officinale L.
J. Cohen 171
Lithospermum strictum Lehm.
J. Cohen 225
Lithospermum tuberosum DC.
J. Cohen 108
Macromeria exserta D. Don
J. Cohen 224
Macromeria hispida M. Martens & Galeotti
J. Cohen 218
Macromeria leonotis I. M. Johnst.
J. Cohen 195
Nuevo León, Mexico
Macromeria longiflora D. Don
J. Cohen 226
Macromeria notata I. M. Johnst.
J. Cohen 188
Nuevo León, Mexico
Macromeria viridiflora DC.
J. Cohen 141
Nomosa rosei I. M. Johnst.
J. Cohen 207
Onosmodium helleri Small
J. Cohen 132
Onosmodium molle (Michx.) Muhl.
Missouri Botanical Garden
Psilolaemus revolutus (B. L. Rob.) I. M. Johnst.
J. Cohen 199
San Luis Potosí, Mexico
DNA extraction, PCR amplification, and sequencing
Annealing tempertures for the cpDNA regions amplified for this study.
Annealing Temperature (°C)
ndhF - rpl32
psbA - trnH
psbJ - petA
trnK - rps16
trnL - rpl32
trnL - trnF
trnQ - rps16
ycf6 - psbM
Sequencing reactions were performed with BigDye 3.1 (Applied Biosystems, CA U.S.A.) terminators and locus-specific amplification primers. Sequencing products were precipitated using a modification of the ethanol/EDTA/sodium acetate method (Applied Biosystems), and automated cycle sequencing was performed by the Life Sciences Core Laboratory Center at Cornell University with an Applied Biosystems (ABI) 3730 DNA Analyzer. Alternatively, sequencing reactions and subsequent steps were performed by the Life Science Core Laboratory Center at Cornell University, using Big Dye terminators and either an ABI 3700 or an ABI 3730. Sequence trace files were compiled, examined, and edited with Sequencher ver. 4.6 – 4.8 (Gene Codes Corporation, MI U.S.A.), and sequences were deposited in Genbank (Genbank accessions FJ827256 – FJ827480).
Alignment, gap coding, and phylogenetic analysis
Initial alignments were performed with MUSCLE (Edgar, 2004) as implemented by the European Bioinformatics Institute’s MUSCLE server (http://www.ebi.ac.uk/Tools/muscle/index.html) using the default settings. Subsequent adjustments were made manually in Bioedit ver. 126.96.36.199 (Hall, 1999). Gaps were coded using simple indel coding (Simmons & Ochoterena, 2000). Inversions were coded as present/absent with the inverted sequence regions excluded from the analyses (Ochoterena, in press). All characters were weighted equally and treated as unordered. Regions that aligned ambiguously (ca. 234 bp of the rpl16 intron) were excluded from analyses.
Maximum parsimony phylogenetic analyses were conducted using TNT (Goloboff et al., 2000), with 10,000 trees held in memory, and 1000 parsimony ratchet iterations performed (Nixon, 1999), with 10% probability of upweighting and 10% probability of downweighting, followed by 100 cycles of tree drifting, 100 rounds of tree fusing, and random sectorial searches (Goloboff, 1999). This search strategy was repeated for ten rounds with five replications per round using the Xmult setting. In total, 50 searches, 50,000 ratchets, 5000 cycles of drift, and 5000 rounds of tree fusing were performed. The commands for the analysis are provided in Appendix 2. Clade support was measured with TNT by conducting 10,000 jackknife replicates (36% removal probability, traditional search strategies, and groups below 1% support collapsed) (Farris et al., 1996). Consistency indices were calculated after removal of parsimony-uninformative characters.
Summary of cpDNA regions included in analyses.
Number of Taxa
Aligned Length (bp)
Informative Nucleotide Site Characters
Informative Structural Characters (gaps and inversion)
Total Informative Characters
% Informative Nucleotide Site Characters
ndhF - rpl32
psbA - trnH
psbJ - petA
trnK - rps16
trnL - rpl32
trnL - trnF
trnQ - rps16
ycf6 - psbM
Although Onosmodium was found to be monophyletic, Macromeria is not a monophyletic group. Psilolaemus is sister to Lithospermum cobrense Greene, and Nomosa and Lasiarrhenum are sister taxa, but neither of these relationships is supported by jackknife values greater than 50%.
Lithospermum officinale and L. erythrorhizon, the two Old World species of Lithospermum included in the analysis, form a clade that is sister to the rest of Lithospermum and other members of New World Lithospermeae. Lithodora diffusa (Lag.) I. M. Johnst. is sister to Lithospermum and other members of New World Lithospermeae with 99% jackknife support.
The analysis resolves Lithospermum and other New World members of Lithospermeae as a monophyletic group, and this is also the case when more taxa are added to the phylogenetic analyses (Cohen, unpublished data). However, Lithospermum is not monophyletic because species of other genera of New World Lithospermeae are interdigitated among species of this genus (Fig. 1). Although species of Lithospermum differ from each other in habit, corolla shape, and corolla color, the other genera of New World Lithospermeae have been segregated from Lithospermum on the basis of the same sorts of features, which appear to be derived vegetative and floral characters. For example, Nomosa and Lasiarrhenum are the only two genera of New World Lithospermeae with completely white corollas and three-veined leaves. In addition, both have corolla shapes, urceolate and campanulate respectively, which are not found in any other species in the group.
Macromeria is a polyphyletic assemblage of species that share a similar phenotype. Species that have been placed in this genus are often large in habit (> 0.75 m tall) with long corollas (> 4 cm) and exserted anthers and stigmas. This suite of characteristics appears to have arisen multiple times independently among species of New World Lithospermeae.
Onosmodium, on the other hand, is resolved as monophyletic, but only two of the seven species of the genus were included in this study. Although the sampling is limited, the group has 99% jackknife support, and with the inclusion of other taxa in the analyses Onosmodium remains monophyletic (Cohen, unpublished data).
Lithodora diffusa is sister to the clade that includes Lithospermum and other genera of New World Lithospermeae. This sister relationship differs from the results obtained by Thomas et al. (2008) for Lithodora and related taxa, in which Buglossoides, rather than Lithodora, was placed as sister to Lithospermum and other genera of New World Lithospermeae. Differences in sampling of both taxa and loci could contribute to these dissimilar results.
Taxonomy and nomenclature
As currently circumscribed, Lithospermum is not monophyletic. All of the species of New World Lithospermeae could be included in Lithospermum, or alternatively the clade containing Lithospermum and other New World Lithospermeae could be divided along different lines than have previously been drawn. We have not observed diagnostic character combinations by which a series of readily recognizable monophyletic genera can be delimited. In addition, most of the monophyletic groups that are readily delimited have five or fewer species. Splitting along these lines would result in several small genera that would be quite difficult to distinguish from each other, and this would not provide a useful taxonomy. The former option, an expansion of the genus, is more useful because Lithospermum and the other species of New World Lithospermeae share multiple synapomorphies, including a nutlet that is erect, smooth to slightly dimpled, white, and lustrous. Although some species of the endemic New World genera of Lithospermeae have not been included in these phylogenetic analyses, careful examination has shown that these species also share the characteristic nutlet, a synapomorphy for the clade, as well as other vegetative and floral characteristics similar to those of species that are included in the analyses. Therefore, a broader circumscription of Lithospermum is proposed, with the genus recognized by the characteristic nutlet in association with corollas that are yellow, yellow-green, white, and/or orange in color. Including all members of the New World Lithospermeae in Lithospermum is a useful and conservative approach to the taxonomy of the group.
Several of the species that are assigned to genera other than Lithospermum have previously been included in Lithospermum, but most others have never been included in the genus. Most species that are part of the former group retain their specific epithet when included in Lithospermum. Species that have not been classified as part of Lithospermum must be transferred to that genus. As Lithospermum is a Linnaean name that has proven to be a catch-all for many species with smooth, white nutlets, several common specific epithets, such as hispida, have been used previously. Therefore, six species require new specific epithets, and those proposed here refer to the unique characteristics and history of these species.
Lithospermum album (G. L. Nesom) J. Cohen, comb. nov. Basionym: Macromeria alba G. L. Nesom, Madroño 36: 28. 1989. Type: Mexico. Tamaulipas, Mpio. Gomez Farias, 5–7 km, NW of Gomez Farias, just S of Agua del Indio, 30 May 1969, A. Richardson 1763 (holotype: TEX).
Lithospermum barbigerum (I. M. Johnst.) J. Cohen, comb. nov. Basionym: Macromeria barbigera I. M. Johnst. J. Arnold Arbor. 16: 189. 1935. Type: Mexico. Nuevo León, N slope of Sierra Tronconal between Canyon de los Charcos and Canyon de San Miguel, ca. 15 mi SW of Galeana, “common in dense oak woods beyond pine-fir belt,” 6000–9000 ft., 4 Jun 1934, C. H. Mueller & M. T. Mueller 741 (holotype: GH; isotypes: F-n.v., MEXU, MICH-n.v., TEX).
Lithospermum chiapense J. Cohen, nom. nov. Basionym: Macromeria guatemalensis I. M. Johnst., J. Arnold. Arbor. 29: 232. 1948, non Lithospermum guatemalense Donn.Sm., Bot. Gaz. 27: 436. 1899. Type: Guatemala. San Marcos, south facing slope of Volcán Tajumulco, between Las Canojas and top of ridge, 7 mi from San Sebastián, 3300–3900 m, 16 Feb 1940, J. A. Steyermark 35898 (holotype: GH; isotype: F).
This species has a range restricted to Guatemala and Chiapas, Mexico; the specific epithet is based on the latter.
Lithospermum dodrantale (I. M. Johnst.) J. Cohen, comb. nov. Basionym: Onosmodium dodrantale I. M. Johnst., J. Arnold Arbor. 18: 22. 1937. Type: Mexico. Nuevo León, Mpio. de Galeana, Peak of Cerro Potosí, “Scattered in colonies in the upper pine wood,” 21 July 1935, C. H. Mueller 2259 (holotype: GH-n.v.; isotypes: F, GH-n.v., MEXU, MICH-n.v.).
Lithospermum exsertum (D. Don) J. Cohen, comb. nov. Basionym: Macromeria exserta D. Don, Edinburgh New Philos. J. 13: 239. 1832. Type: Mexico. Without locality, 1787–1804, Sessé & Moçiño s.n. (holotype: not found).
Lithospermum helleri (Small) J. Cohen, comb. nov. Basionym: Onosmodium helleri Small, Fl. S.E. U.S. 1000, 1337. 1903. Type: U.S.A. Texas: Kerr Co., along Bear Creek, 1600 – 2000 ft, 30 Apr 1894, A. A. Heller 1682 (holotype: NY; isotypes: UC-n.v., US).
Lithospermum johnstonii J. Cohen, nom. nov. Basionym: Macromeria hispida M. Martens & Galeotti, Bull. Acad. Roy. Sci. Bruxelles 11: 339. 1844, non Lithospermum hispidum Forssk., Fl. Aegypt.-Arab. 39. 1775. Type: Mexico. Michoacán: near Morelia, Cerro de Quinzeo, 6500 – 8000 ft, 1840–1844, Galeotti 1917 (holotype: BR-n.v., isotypes: GH).
This species is named for Ivan M. Johnston, Boraginaceae systematist. His work on Lithospermum, Lithospermeae, and Boraginaceae has provided great insight for many botanists.
Lithospermum leonotis (I. M. Johnst.) J. Cohen, comb. nov. Basionym: Macromeria leonotis I. M. Johnst. [“leontis”], J. Arnold Arbor. 16: 188. 1935. Type: Mexico. Nuevo León: “ascent into Taray,” ca. 15 mi SW of Galeana, ca. 8000 ft, 6 June 1934, C. H. Mueller & M. T. Mueller 754 (holotype: GH; isotype: TEX).
Lithospermum macromeria J. Cohen, nom. nov. Basionym: Macromeria viridiflora DC. in A. P. de Candolle & A. L. P. P. de Candolle, Prodr. 10: 68. 1846, non Lithospermum viridiflorum Roxb., in Carey & Wallich, Fl. Ind. 2: 4. 1824. Type: Mexico, without locality, 1787–1804, Sessé & Mociño 5131 (holotype: M-n.v.; probable fragment of holotype: F-n.v., GH; photo of holotype: GH, MICH-n.v.).
This specific epithet is derived from the genus Macromeria, the largest genus of Lithospermeae endemic to the New World. This species was given this epithet because of its broad, international range, from western Mexico to the southwestern United States.
Lithospermum notatum (I. M. Johnst.) J. Cohen, comb. nov. Basionym: Macromeria notata I. M. Johnst., J. Arnold Arbor. 35: 13. 1954. Type: Mexico. Nuevo León: Ascent of Sierra Infernillo, ca. 15 mi. SW of Galeana, “Common over small areas just below the peak,” 9000–10,000 ft, 16 June 1934, C. H. Mueller & M. T. Mueller 830 (holotype: GH; isotypes: F, MICH-n.v., TEX).
Lithospermum oaxacanum (B. L. Turner) J. Cohen, comb. nov. Basionym: Onosmodium oaxacanum B. L. Turner, Phytologia 78: 53. 1995. Type: Mexico. Oaxaca, Llano Udadi, 4 km SE of San Andreas Lagunas, Pinus pseudostrobus woodland, 2380 m, 10 July 1981, A. Garcia M. 504 (holotype: MEXU).
Lithospermum onosmodium J. Cohen, nom. nov. Basionym: Onosmodium bejariense DC. in A. P. de Candolle & A. L. P. P. de Candolle, Prodr. 10: 70. 1846, non Lithospermum bejariense DC. in A. P. de Candolle & A. L. L. P. de Candolle, Prodr. 10: 79. 1946. Type: U.S.A. Texas, “Bejar ad Rio de la Trinidad,” May 1828, J. L. Berlandier 1681 (holotype: G-DC; isotype: GH; photo of isotype: F-n.v., GH, MICH-n.v.).
This specific epithet is derived from the genus Onosmodium, the second largest genus of Lithospermeae endemic to the New World.
Lithospermum pinetorum (I. M. Johnst.) J. Cohen, comb. nov. Basionym: Lasiarrhenum pinetorum I. M. Johnst., J. Arnold Arbor. 16: 187. 1935. Perittostema pinetorum (I. M. Johnst.) I. M. Johnst. J. Arnold Arbor. 35: 30. 1954. Type: Mexico. Oaxaca(?), September 1841(?), Ghiesbreght 311 (holotype: P).
Lithospermum rosei (I. M. Johnst.) J. Cohen, comb. nov. Basionym: Nomosa rosei I. M. Johnst., J. Arnold. Arbor. 35: 25. 1954. Type: Mexico, in Sierra Madre near the southern border of the state of Durango, Aug 16 1897, J. N. Rose 2360 (holotype: GH).
Lithospermum rzedowskii J. Cohen, nom. nov. Basionym: Macromeria pringlei Greenm., Proc. Amer. Acad. Arts 34: 570. 1899, non Lithospermum pringlei I.M.. Johnst., Contr. Gray Herb. 70: 22. 1924. Onosmodium pringlei (Greenm.) J. F. Macbr. Contr. Gray Herb. n.s. 49: 20. 1917. Type: Mexico. Hidalgo, Sierra de Pachuca, 10,000 ft., 4 Aug 1898, C. G. Pringle 6949 (holotype: GH; isotypes: F, MEXU, PH-n.v., UC-n.v., US).
This species is named for Jerzy Rzedowski. Whether by chance or by design, he has collected a great number of specimens of Lithospermum and other New World Lithospermeae, and these collections have been very helpful in studying the variation in these groups.
Lithospermum trinervium (Lehm.) J. Cohen, comb. nov. Basionym: Onosma trinervium Lehm., Pl. Asperif. Nucif. 2: 37. 1818. Lasiarrhenum trinvervium (Lehm.) B. L. Turner Phytologia 77: 39. 1994. Type: “Habitat in America Meridionali,” Humboldt & Bonpland s.n.? (holotype: not located).
According to Turner (1994b), the type is from Mexico, with the following information provided by Lehmann: “Habitat in America Meridionali;” however, Lehmann did not name the collector or provide a collection date for the specimen. Turner (1994b) states that the type is possibly based upon a specimen from Humboldt and Bonpland’s collection from Michoacán in 1803, and that this specimen is possibly at MEL, but no specimen by that name could be found there.
Lithospermum turneri J. Cohen, nom. nov. Basionym: Macromeria hintoniorum B. L. Turner, Phytologia 77: 398. 1994, non Lithospermum hintoniorum B. L. Turner, Sida 20: 501. 2002. Type: Mexico. Guerrero, Teotepec, ca. 12˚ 27′ N, 100˚ 10′ W, pine forest, 2750 m, 16 July 1939, G. B. Hinton et al. 14439 (holotype: NY; isotypes: F, NY, US).
This species is named for Billie L. Turner. His work on Lithospermum and New World Lithospermeae has been helpful in understanding these taxa.
Lithospermum unicum (J. F. Macbr.) J. Cohen, comb. nov. Basionym: Onosmodium unicum J. F. Macbr., Contr. Gray Herb. n.s. 49: 21. 1917. Type: Mexico. San Luis Potosí, Alvarez, 13 – 23 July 1904, E. Palmer 185. (holotype: GH; isotype: F).
This research was supported by grants from the American Society of Plant Taxonomists, the Harold Moore Jr. Funds, Cornell University’s chapter of Sigma Xi, the Cornell University Graduate School, and Cornell University’s Latin American Studies Program. Without Shannon C. K. Straub, María Hilda Flores Olvera, Helga Ochoterena, Socorro Gonzalez, Paty Ledesma Hernandez, Fernando Alzate, Lucía Vázquez, Janelle M. Burke, and Caroline D. Kellogg, it would have been much more difficult to locate and collect these plants. In addition, the National Botanic Garden of Belgium, Missouri Botanical Garden, and Cornell Plantations provided leaf material, and the Royal Botanic Garden, Kew supplied one DNA isolation. Thanks to Caroline D. Kellogg for her support and comments on this manuscript. James L. Reveal gave invaluable advice concerning the nomenclature of Lithospermum as well as helpful comments on the manuscript. James S. Miller’s specific comments and advice allowed this manuscript to be ready for submission in a timely manner. Shannon C. K. Straub gave helpful comments on an early draft, and thanks to Monica Geber, M. Alejandra Gandolfo, Michael Simpson, and Lawrence Kelly for their detailed reading and comments and corrections.