Phyiologia (August 1995) 79(2):89-92. TAXONOMIC STUDY OF HEDYOTIS PALMERI (RUBIACEAE) B.L. Turner DepartmentofBotany, UniversityofTexas,Austin,Texas 78713 U.S.A. ABSTRACT Hedyotispalmeri(A. Gray) W.H. Lewis{-Houstoniapalmed A. Gray) is aspeciesofnorthcentral Mexicooccurringinmostly shallow soils from 1000- 2200 m. Two morphogeographical infraspecific categories are recognized: var. pabneri (including H. longipes S. Wats.), occurring in southeastern Coahuilaand mostofNuevoLe6nfrom 1600-2200m; and var. muzqiiizana B.L. Turner, var. nov., occurring in northcentral Coahuila mostly at 1000- 1600 m. The latter differs from the former in being a taller plant with larger corollasand longerpedicels. A mapshowing the distributions of the two taxa isincluded. Lectotypification forH. longipesandH.palmeriis provided. KEY WORDS: Rubiaceae,Hedyotis,Houstonia,Mexico,systematics Terrell (1991) provided an overview of the genera Hedyotis, Houstonia, and Oldenlandia forNorthAmerica. Inthis,Hedyotispalmeri(A. Gray) W.H. Lewis was positionedinthegenusHoustonia, subgenusEricotislcncW. This subgenus includes Hedyotis acerosa A. Gray which I have recently studied (Turner, 1996), concluding thatitisseeminglyadequatelytreatedasanelementofHedyotis. In working over that complex 1 became interested in the regional variation displayed by H. palmeri, hence thepresentpaper. Terrell did not recognize infraspecific categories under Hedyotis palmeri, but a sortingofthespecimensavailabletome, mostoftheseannotated by him, showed that there was aseries of populations in northcentral Coahuila made up of larger wirier plants, with larger corollas on more elongate pedicels than occurs in typical populationalelementsofH.paltneri. Thetwo series of populations apparently do not coexist, and while clear intermediates between these are not known, their close relationshipissoobviousthatI havedescribed thenew taxonasbutvarietallydistinct. A key to these two varieties follow, along with a map showing their distribution (Figure 1), based uponmaterial on fileatGH, LL, SRSC,TEX. 89 Figure 1. Distribution of Hedyotis pabneri: var. muzquizaiia (open circles); var. palmeri(closedcircles). i . Turner StudyoiHedyotispabneri 91 Key tovarietiesofHedyotispalmer Mature corolla tubes mostly (6-)8-10 mm long; pedicels mostly 20-30 mm long; n Coahuila var. muzquizana Mature corolla tubes mostly 4-5{-8) mm long; pedicels mostly 5-20 mm long; s Coahuila, Nuevo Le6n vanpalrneri HEDYOTIS PALMERI (A. Gray) W.H. Lewis var. PALMERI, Rhodora 63:222. 1961. BASIONYM: Hoiistonia palrneri A. Gray, Proc. Amer. Acad. Arts 17:202. 1882. TYPE MEXICO. Coahuila: ''Lerios, 45 mi E of Saltillo", Jul 1880,EdwardPabner397(LECTOTYPE [hereselected]: GH!). The lectotype is mounted on the same sheMet with two other collections, all of these cited in the protologue: Pabner398, 1880, from "40 mi S of Saltillo", and Pabner 2117, Jul 1880,from "6mi EofSaltillo". Theseveral specimensareverysimilarbut the collectionselectedasthe lectotype is betterdeveloped as to flowering and fruiting material. Houstonia longipes S. Wats., Proc. Amer. Acad. Arts 18:97. 1883. Hedyotis /oAz^/pe5(S. Wats.) W.H. Lewis, Rhodora63:222. 1961. TYPE: MEXICO. NuevoLe6n: Monterrey, Feb 1880, Edward Pabner 395 (LECTOTYPE [here selected]: GH!). The lectotype is mounted on the same sheet with two other collections: E. Pabner394, Sep 1880, from Monclova, Coahuila, and Gregg s.n., 29 May 1847, from "Cerralbo", Coahuila (?). All of these are very similarandall werecited intheprotologue. TheGreggspecimens are the only ones having both flowers and fruits, the corolla tubes being ca. 4 mm long. Corollasareabsentontheremainingcollections. Thisisthecommonlycollected widespread variety of the species and is known to me only by collections obtained from the south and east of var. muzquizana (Figure 1). HEDYOTIS PALMERI (A. Gray) W.H. Lewis var. MUZQUIZANA B.L. Turner, var. nov. TYPE: MEXICO. Coahuila: Mpio. M. Muzquiz, ca. 130 road kmNWofMuzquizonHwy2A, 'YnidslopeofSa. La Encantada along road up to NW tunnelentrance toLaEncantadabasinand miningarea. Steep - facingslope, . . common but scattered, mostly in moister microsites", 28° 30' 40" N x 102'' 19' 30" W, 3 Jun 1992, Guy Nesom 7380 (with M. Mayfield) (HOLOTYPE TEX!;Isotype: MEXU). Similis H. paltneri (A. Gray) W.H. Lewis var. palnieri sed differt tubis corollarum plerumque 8-10 mm longis (vice tuborum plerumque 4-6 mm longorum)etpedicellisplerumque20-30mm longis(vice5-20mm longis). ADDITIONAL SPECIMENS EXAMINED: MEXICO. Coahuila: Mpio. M. Muzquiz, Cuestadel Plomo, 1000 m,7Jun 1972, M.C.Johnstonetal. 7550p (TEX); Muzquiz, spring 1935, Marsh 330 (GH,SRSC,TEX); Santa Rosa Mts., 8 Jul 1938, Marsh 1251 (GH,TEX); 15 air km NW of La Babia, 18 May 1992, Mayfield 1426 A PHYTOLOGI 92 August 1995 volume79(2):89-92 (TEX); SW margin of Serranias del Burro, 1400-2100 m, 23 Jun 1991, Ruiz 47 (TEX);RanchoAguaDulce, 1 Jul 1936, Wynd&Mueller400(GH). Nearly all of the specimens cited above have the characters alluded to in the diagnosis, and it is clear that these represent populational units distinct from var. palmeri. Additionally, the plants concerned, in general, appear to be taller, wirier, withalessbranchedinflorescencethanoccursin var.palmeri Terrellannotatedseveralormore ofthe above sheets as Hedyotispalmeri without comment. In spite of numerous collections of var. palmeri on file at LL, TEX (40 sheets), I have not detected any clear intermediates between these allopatric entities except for a single collection from "Alamar", Pablillo, SE of Galeana, Nuevo Le6n {Pennell 17191 [GH]), having corolla tubes 6-8 mm long, otherwise it is similar to var. palmeri. Late-flowering specimens of var. muzquizana, however, occasionally producesmall flowers (e.g., Wynd& Muller400). It is possible that future field workers will elevate var. muzquizana to specific rank,typical specimensdifferingmarkedlyfrom var.palmeri. ACKNOWLEDGMENTS I amgrateful to GH and SRSC for the loan of materials. Gayle Turner provided theLatindiagnosis,andsheandPieroDelpretereviewed thearticle. UTERATURECITED Terrell, EE. 1991. Overview and annotated list of North American species of Hedyotis, Houstonia, Oldenlandia, and relatedgenera. Phytologia 71:212-243. Turner, B.L. 1996. Taxonomy of the Hedyotis acerosa (Rubiaceae) complex. Phytologia 79:83-88.