Almeda: Systematic* of the Genus Monochaetum () 111

TABLE 16 Pollen Viability of Monochaetum tenellum, M. floribundum and a Putative Hybrid

No. of Anther grains series viable scored

M. tenellum Skutch 1687 large 250 98 E small 250 98 E E in M. tenellum X floribundum E ro in n Skutch 1752 large 250 10 small 250 35 M. floribundum Skutch 1748 large 250 99 small 250 99

Marcos, Standley 662)4 (F), Standley 66237 (F); on rd 8-18 mi NW of San Marcos, Steyermark. 3)603 (F, US); 2 mi S of San Sebastian, Sierra Madre mts, Williams, Molina 9 Williams 2)937 (F, GH, NY, US, W); canyon S of San Marcos toward Castalia, Williams, Molina 9 Williams 26177 (F, G); slopes of Volcan Taju- mulco, Williams et al. 271)2 (F, NY). Solola: Guat Hwy #CA1 ca. 31.3 mi W of Panajachel, Almeda 9 E Luteyn 1716 (DUKE, GH, US); 12 km SE of Panajachel, Burch ))30 (USF); Los Encuentros, Seler 23)9 E E (CAS, GH, US); Santa Barbara, Shannon )22 (US; photograph, NY); wet banks and ravines near Nahuala, CO E uo Sierra Madre mts, Williams, Molina 9 Williams 2322) (F, G, NY, W); ravine ca. 4 km E of Godinez, Wil- liams, Molina 9 Williams 2)207 (F, GH, NY, US, W). Totonicapan: cloud forest of Maria Tecum on rd to Los Encuentros, Molina 1)909 (MO, NY, US, WIS); wet bank near Momostenango, Molina 2143) (F, GH, NY); rd between San Francisco El Alto and Momostenango, Standley 84002 (F-, NY); Sierra Madre mts N of San Carlos, Williams, Molina 9 Williams 22)7 4(1, G, NY, W); Sierra Madre mts 20-25 km N of Cristobal, Williams, Molina 9 Williams 22665 (F, G, NY, W). Putative hybrid between Monochaetum tenellum and M. floribundum. — GUATEMALA. Quiche: vicinity of Nebaj, Skutch 17)2 (A, NY).

18. Monochaetum compactum Almeda, sp. nov. (Fig. 30)

Frutex erectus ad 2 m alms; rami densi hirsuti, trichomatibus barbellatis aliquando glandulosis. Foliorum lamina elliptica vel elliptico-ovata, (7-)9-23(-28) mm longa et (S-)4-l 1(-1S) mm lata, 5-plinervata, nervorum E pari exteriore plerumque inconspicuo. Inflorescentiae terminales, dichasiales, bracteis ellipticis, ovatis, sub- E 01 orbicularis, obovatis, oblanceolatis ad spathulatis, (2. 5-)4-6(-9) mm longis et 2-5 mm latis. Calycis lobi lan- co £ C ceolati ad oblongi, ad apicem obutsi vel rotundati, 4-6 mm longi et (1 .5-)2-3 mm lati; persistentes. Petala magenta vel atrorosea, anguste elliptica vel obovata, 12.5-19 mm longa et 9-12 mm lata. Staminum maio- rum filamenta 6-8 mm longa, thecis (5-)6-8(-9) mm longis, appendicibus dorsalibus 3-5 mm longis. Stami- num minorum filamenta 7-9 mm longa, thecis 4-5. 5 mm longis, appendicibus dorsalibus 2. 5-4. 5 mm longis. Stylus 5-7 m longus. Hypamhium (maturum) urceolatum vel suburceolatum, 4.5-7 mm longum et 3.5-5(-6) mm latum, strigosum, trichomatibus barbellatis et glandulosis. Semina 0.5-0.8 mm longa, brunnea, minute foveolata, cochleata. Erect, compactly branched 1-2 m tall with terete stems; cauline internodes spreading hirsute. Tri- chomes white or more commonly tawny colored, distinctly barbellate, less than 1 mm long and often inter- III! mixed with purplish, glandular trichomes of similar length on the younger shoots. Nodal trichom.es similar 0O)l —CD —(D —TO CD £ CD CD to the internodal ones, flexuous, 1.5-3 mm long and commonly two or three times the length of the inter- _J CO Q_ D- 112 University of California Publications in Botany Almeda: Systematic* ofth

nodal trichomes. Older stems and basal br leaves membranaceous, not markedly ani appressed, barbellate trichomes in 4(-6) w nerves. Lower leaf surface widely spreading elliptic to elliptic-ovate, (7-)9-23(-28) mm lo basally, 5-plinerved below with three elevat< ous for the basal half or third of the blade 1 distally, with the margins entire. Petioles slei mostly terminal, a 2-3(-4) times compound < (to 1 cm) between floral bracts; overall sym aborted development of lateral branches in e mm long, 2-5 mm wide with slender (somewh bracts narrowly elliptic to ovate and the uppe obtuse apically, acute to cuneate basally; upp ally pustulate trichomes and spreading, glan appressed, barbellate trichomes and spreadii obconic, often deep burgundy with appressec with smooth, spreading, glandular trichomes ceolate, 4-7 mm long, 3.5-5(-6) mm in diame Sepals spreading to ascending, narrowly lanc< usually copiously strigose without, 4-6 mm Ion glabrous, or with one or two trichomes apicall mm wide. Antepetalous stamina!filaments 6- mm wide, the apical pore 0.5 or less in diamet 3-5 mm long, 0.5 mm wide. Antesepalous sta with red basally along the connective, 4-5.5 I appendages yellow, linear to linear-lanceolat< glandular trichome at the apex. Ovary (at m setose apically. Style 5-7 mm long. Seeds 0.5- arcuate. Type.—PANAMA. Chiriqui Province: Llanos can on rd to Cerro Punta, elev. 1900-2000 n DUKE; isotypes, BR, F, G, GH, K, LL, ME* Flowering. —Apparently at peak flowering fr during most intervening months. Habitat and distribution. —Known only fron cene volcano in the Province of Chiriqui, Panar dally common along the Llanos del Volcan desc of the shrubby vegetation. It has also been colle( in open meadows above treeline. Although it is I habitats, it also occurs less frequently along tr northern and eastern slopes of Baru (fig. 17).

The included here form a mo: which differs from other species by it elliptic-ovate leaves (mostly 9-23 mm k H elliptic to narrowly obovate petals. One specimen, McCorkle C-150, col differs from typical material in having cauline trichomes that are appressed ra Fig. SO. Monochaetum compactum. A, habit, X \i; B, petal, X ca. 3; C,E, abaxial surface of representa- be a local response to environmental cc tive floral bracts, X 7; D, mature and calyx lobes, X 4; F, abaxial surface of a typical leaf, X 5; nition. G, seeds, X 22; H, ovary, style and unreceptive stigma, X 5. (A & H from Almeda 9 Wilbur 1564; B-G from Although only two collections of M. Almeda 9 Wilbur 1024.) when he prepared a treatment of the 1 ions in Botany Almeda: Systematics of the Genus Monochaetum (Melastomataceae) 113

nodal trichomes. Older stems and basal branches woody, reddish brown, the bark exfoliating. Principal leaves membranaceous, not markedly anisophyllous, upper leaf surface with antrorsely spreading or appressed, barbellate trichomes in 4(-6) well-defined, longitudinal belts between the impressed primary nerves. Lower leaf surface widely spreading hirsute on the primaries and hirtellous between them. Blades elliptic to elliptic-ovate, (7-)9-23(-28) mm long, (3-)4-l 1(-13) mm wide, acute apically, subacute to rounded basally, 5-plinerved below with three elevated central nerves, the submarginal pair elevated and conspicu- ous for the basal half or third of the blade length, becoming depressed and confluent with blade margins distally, with the margins entire. Petioles slender, (l-)2-6(-9) mm long, to 1 mm wide, hirsute. Inflorescence mostly terminal, a 2-S(-4) times compound dichasium appearing congested because of the short internodes (to 1 cm) between floral bracts; overall symmetry of the inflorescence often appearing uneven because of aborted development of lateral branches in each of the S-flowered dichasial units. Floral bracts (2.5-)4-6(-9) mm long, 2-5 mm wide with slender (somewhat compressed) petioles 1-3 mm long; lower (somewhat larger) bracts narrowly elliptic to ovate and the uppermost rotund, obovate, oblanceolate, or spatulate, subacute to obtuse apically, acute to cuneate basally; uppermost bracts usually 3-nerved, covered with a mixture of bas- ally pustulate trichomes and spreading, glandular trichomes. Floral pedicels (5-)6-10(-12) mm long with ± appressed, barbellate trichomes and spreading, glandular ones. Hypanthium (at anthesis) campanulate to obconic, often deep burgundy with appressed, barbellate trichomes 0.5-2 mm long, frequently intermixed with smooth, spreading, glandular trichomes to 1 mm long. Hypanthium (at maturity) urceolate to subur- ceolate, 4-7 mm long, 3.5-5(-6) mm in diameter at the broadest point; longitudinal ribs obscure on drying. Sepals spreading to ascending, narrowly lance-deltoid or linear-oblong, obtuse to rounded apically, ciliate, usually copiously strigose without, 4-6 mm long, (1.5-)2-3 mm wide basally, persistent. Petals deep magenta, glabrous, or with one or two trichomes apically, broadly elliptic to narrowly obovate, 12.5-19 mm long, 9-12 mm wide. Antepetalous staminalfilaments 6-8 mm long; anthers reddish-magenta, (5-)6-8(-9) mm long, 1 mm wide, the apical pore 0.5 or less in diameter; appendages reddish-magenta but yellow apically, falcate, 3-5 mm long, 0.5 mm wide. Antesepalous staminal filaments 7-9 mm long; anthers yellow, often suffused with red basally along the connective, 4-5.5 mm long, 1 mm wide, apical pore ca. 0.5 mm in diameter; appendages yellow, linear to linear-lanceolate, 2.5-4.5 mm long, 0.5-1 mm wide, rarely bearing a stout, glandular trichome at the apex. Ovary (at maturity) ovoid to obovoid, the body essentially glabrous but setose apically. Style 5-7 mm long. Seeds 0.5-0.8 mm long, light brown, minutely foveolate, cochleate to arcuate. Type.—PANAMA. Chiriqui Province: Llanos on W side of Volcan Chiriqui ca. 4 mi NE of El Hato del Vol- can on rd to Cerro Punta, elev. 1900-2000 m, December 26, 1971, Almeda-9 Wilbur 1024 (Holotype, DUKE; isotypes, BR, F, G, GH, K, LL, MEXU, MICH, MO, NY, P, PMA, UC, US, W). Flowering.—Apparently at peak flowering from November through March, but sporadic flowering occurs during most intervening months. Habitat and distribution.— Known only from the slopes and canyons bordering Volcan Bani, a Pleisto- cene volcano in the Province of Chiriqui, Panama, at elev. 1500-3000 m, Monochaetum compactum is espe- cially common along the Llanos del Volcan described by Terry (1956), where it forms a conspicuous element of the shrubby vegetation. It has also been collected at higher elevations on the western flanks of the volcano in open meadows above treeline. Although it is the only Panamanian species found in the above-mentioned habitats, it also occurs less frequently along trailsides and disturbed sites bordering cloud forests on the northern and eastern slopes of Barii (fig. 17).

The plants included here form a morphologically and geographically cohesive taxon which differs from other species by its compactly branched habit, small, elliptic to elliptic-ovate leaves (mostly 9-23 mm long), spreading cauline trichomes, and broadly elliptic to narrowly obovate petals. One specimen, McCorhle C-150, collected at 2900 m on the slopes of Volcan Bani, differs from typical material in having narrowly elliptic leaves and longer internodal cauline trichomes that are appressed rather than spreading. This variation appears to be a local response to environmental conditions and seems unworthy of formal recog- tal X ca. 3; C,E, abaxial surface of represents •s X 4- F abaxial surface of a typical leaf, X 5; nition. "(A & H from Almeda 9 Wilbur If 64; B-G from Although only two collections of M. compactum were available to Gleason (1958) when he prepared a treatment of the Melastomataceae for the Flora of Panama, he 114 University of California Publications in Botany Almeda: Systematic!,

overlooked their distinctive features and chose to include them with M. rivulare, a he relied heavily on the presei Mexican species herein referred to the synonymy of M. floribundum. One of the two ifferences in foliar size. The collections examined by Gleason, Woodson et al. 906, consists of M. compactum and complex makes questionable th M. floribundum and may have influenced his broadened concept of variability within any populations of Monochaet* M. rivulare. collections from the area have Relationships and Sympatry. —Like other species of Monochaetum in Mesoamerica, Tucker 1257 (F, NY, UC, US) h M. compactum appears to have evolved in a restricted area from ancestral stock per- 1-6 to 3.2 cm in length and at haps resembling M. floribundum. Their close relationship is reflected in this treat- 7Wa(F.UC) is identical to these ment by inclusion in the same species-group. specimens fall within the range < The mixed collection of M. compactum and M. floribundum mentioned above scription of M. salvadorense, it d could mean that these taxa were found in close proximity. During field studies, how- line pubescence. All evidence cc ever, I have never seen these species growing together nor have I seen M. compactum deppeanum and, with some res. growing with other species. time. Until additional material is as an uncertain species. Representative specimens. — PANAMA. Chiriqui: Llanos on W side of Volcan Chiriqui, Almeda 9 Wilbur 1564 (BR, CAS, DUKE, F, GH, MO, US); Volcan Chiriqui, Boquete, Davidson 884 (A, DS, F, MO, US); 0.6 mi N of Boquete towards El Sato, Luteyn 1303 (BR, DUKE, F, MICH, MO, US); side of Baru mt, McCorhle C-150 (FSU); vicinity of Boquete, "El Velo," Stern, Eyde 9 Ayensu 1986 (MICH, US); canyon 8 mi NE of El Volcan, Tyson 842 (FSU, MO); W slope of El Baru, Tyson 9 Loftin 6131 (FSU); Llanos ca. 3 mi N of El Hato del Volcan, Utley et al. 252 (DUKE); lava field NE of El Hato del Volcan near Aguacate, Wil- Monochaetum guatemalense Stan bur etal. 10980 (DUKE, F, G, GH, MICH, MO, NY, P, US, WIS); W slope of Volcan Chiriqui, Wilbur el 1944. al. 11032 (DUKE); trail from Bajo Grande, 2 km E of Cerro Punta, Wilbur et al. 15136 (DUKE); grassy Type. -GUATEMALA. Huehuetenango- vi field between El Hato and Volcan Chiriqui, Wilbur et al. 15395 (DUKE, G, UC); 4 mi NE of El Hato, Wit- Heterocentron elegans (Schlecht.) Ku bur 9 Teeri 13070 (KR, DUKE, F, FSU, GH, K, MEXU, MICH, MO, NY); lava field between Volcan Chi- riqui and Aguacate, Wilbur 9 Teeri 13319 (BM, CAS, DUKE, MO, MSC, P, W); vicinity of Casita Alta, Monochaetum pulchellum Decaisn Volcan Chiriqui', Woodson, Allen 9 Seibert 906 (GH, NY, in part). (nom. nud.) = M. pulcflrum Decaisne . The holotype of M. pulchrum ha UNCERTAIN SPECIES Two years after the publication of/ sum for plants that are identical to 1. Monochaetum salvadorense S. Winkler, Bot.Jahrb. 83:364. pi. lOd. 1965 tion, Naudin also recognized M. pul made no mention of M. pulchrum. I Type.—EL SALVADOR. Dept. of Santa Ana: Volcan Santa Ana, 2100 m, June 27, 1962, Winklers.it. Ithough he ascribed the correct cita (Holotype, Herb. S. Winkler, TUBI). -r name has been perpetuated in all Erect shrub 1-2 m tall. Cauline internodes sparsely hirsute. Principal leaves entire, elliptic, acuminate, to I and has invariably been attributed 30 mm long, 14 mm wide, covered with trichomes between the primary nerves above, with trichomes pri- Standley, 1924; Triana, 1871) marily on the elevated primaries below; petioles to 5 mm long. Flowers solitary or paired, borne terminally on lateral branches; petals pink, about 12 mm long. Calyx lobes 6-8 mm long with spreading trichomes, red apically, triangular.

The description given above is drawn totally from the protologue, but it provides in- sufficient detail to allow comparison with other taxa. According to Winkler (1965) this species approaches M. hartwegianum Naud. but differs in having solitary or paired flowers. Monochaetum hartwegianum is restricted to and resembles the widespread M. floribundum of Mexico and . The original descrip tion of M. salvadorense is supplemented by a photograph of the type and figures out' lining foliar shape, relative foliar size, and posture of cauline pubescence. In these characters, M. salvadorense is most similar to what Winkler describes as M. montecris- tense (= M. deppeanum) in the same publication. It is possible that M. salvadorense is a variant of M. deppeanum. Although Winkler makes no mention of the diagnostic characters used in circumscribing his new species, his key to the species suggests thai