Monographs Details: Myrcia decorticans DC.
Authority: Maguire, Bassett. 1969. The botany of the Guayana Highland-part VIII. Mem. New York Bot. Gard. 18: 1-290.
Family:Myrtaceae
Scientific Name:Myrcia decorticans DC.
Description:Distribution and Ecology - Venezuela. Delta Amacuro: Bosque pluvial, Ede Rio Grande, E N E de El Palmar, cerca de los limites del Estado Bolivar, 16 Jan1965 (fr), Marcano Berti 585 ( M I C H ) , 22 Jan 1965 (fl), Marcano 636 ( M I C H ),23 M a y 1964 (sterile), Marcano 183 ( M I C H ) . Bolivar: Sierra Imataca, Cerro LaReforma, N of El Palmar, elev 200-250 m, 15 Dec 1960 (fr), Steyermark 88076( M I C H ) ; 5-7 k m E of El Crucero, E S E of Villa Lola, elev 300 m, 16 Jul 1960 (bud),Steyermark 86417 (MVCYi).

Discussion:

Myrcia? leucophlaea D C , DC. Prodr. 3: 247. 1828.

?Myrcia lasiopus D C , DC. Prodr. 3: 253. 1828.

Aulomyrcia polymorpha Berg, Linnaea 27: 46. 1855; Mart. Fl. Bras. 14(l): 78. 1857.

Calyptranthes tobagensis Krug & Urb. ex Urb., Bot. Jahrb. 19: 593. 1895.

Myrcia tobagensis (Krug & Urb.) Urb., Repert. Sp. Nov. 14: 336. 1916.

Aulomyrcia tobagensis (Krug & Urb.) Amsh., Rec. Trav. Bot. Neerl. 39: 155. 1942.

?Marlierea gleasoni McVaugh, Mem. N. Y. Bot. Gard. 10(1): 83. 1958

proposed the name Aulomyrcia polymorpha to include the plants that de Candolle had assigned to four different species of Myrcia, viz, M . decorticans, M . lasiopus, M . leucophlaea and M . duriuscula. I should agree after examination of the specimens in the Martius herbarium at M , that M . decorticans and M . leucophlaea are the same, and perhaps M . lasiopus as well. The type of M . decorticans (cf Field Mus. neg 19842) agrees in most details with West Indian and other South American specimens that have previously been called Myrcia, or Aulomyrcia, tobagensis. The Martius specimen, collected according to the label in the State of Bahia, is rather more heavily pubescent than specimens from further north, and the flowers are mostly sessile or very short-pedicellate, but in general appearance, in the minutely pebbled surface of the lower side of the leaf, in the rimose petioles and the irregularly divided and partly deciduous calyx, a strong similarity is apparent. The plant here called Myrcia decorticans seems to have some affinities with the small group of species that includes M . inaequiloba, M . lucida, and the West Indian "Myrcia edulis var dominicana." All these have in common coriaceous and essentially glabrous acuminate leaves with impressed midvein; glabrous flowers (even if the panicle-branches are pubescent as they usually are); calyx-lobes thickly pubescent within, 5 or more often 4 in number, free in the bud and more or less deciduous from the margin of the hypanthium at anthesis; persistent bracts in the inflorescence; and rather small globose fruit. I can find no significant differences between Antillean material of Calyptranthes [Myrcia] tobagensis (e.g., Eggers 5828, an isotype at A; and Broadway 4003, a flowering specimen also from Tobago, at G and M I C H ) , and the Venezuelan material cited below. There is some variation in panicle-size and in density of pubescence. In this species the hairs of the inflorescence and those of leafy branchlets tend to be strongly antrorsely appressed, stiff, up to 0.5 m m long, yellowish-white, and laterally attached at or near the base; that is, some of them are demonstrably dibrachiate, with a long branch directed forward, and a much shorter opposing branch. Fruiting specimens of M . tobagensis, from which most of the pubescence has disappeared, are hardly to be distinguished from M . inaequiloba except by the corkyrimose petioles of the former.

The plant from British Guiana that I described in 1958 as Marlierea gleasoni seems unquestionably to belong to the same assemblage, although in the two known collections the flowers are at least partly 5-merous. In M . decorticans, including the Venezuelan material, and in the same or closely related taxa in the Guianas and in Amapa and Para, Brazil, the flowers are prevailing 4-merous. Perhaps several species are involved, but the available material is very scant, and I a m reluctant to draw specific lines on the basis of 4-merous vs. 5-merous flowers when in every other respect the specimens are so much alike. In M . gleasoni the hypanthium at anthesis splits radially almost to the margin of the staminal ring (for which reason it was originally described as a species of Marlierea), whereas in most specimens of Myrcia decorticans the calyx-lobes are wholly or partly deciduous from the nearly entire rim of the hypanthium. Amshoff in 1942 (Rec. Trav. Bot. Neerl. 3 9: 155) reported Aulomyrcia tobagensis from Suriname, on the basis of two collections made by Gonggrijp in 1918. These specimens, which I have seen through the courtesy of Dr. A. M . W . Mennega, are very like those of .1. tobagensis except that they are glabrous or essentially so; the flowers are tetramerous, as noted by Amshoff. In a later paper (Rec. Trav. Bot. Neerl. 42: 9, 10. 1950) Amshoff made these same collections the basis of a new species, Aulomyrcia tetramera, stating that in A. tobagensis, "though in many respects very similar, the inflorescence is puberulous and the structure of the calyx different, the sepals being very short." The inner calyx-lobes in the Suriname specimens, as noted by Amshoff, are about 1.5 m m long; in specimens before me, from Tobago and Venezuela respectively, the equivalent lobes are 1.0 and 1.5 m m long. I cannot say what the importance of these differences may be. The following additional collections evidently belong to the tobagensis-tetramera alliance, but differ as noted in parenthetical comments. V E N E Z U E L A . Sucre: Peninsula de Paria, Cerro Patao elev 800-825 m, 19 Jul 1962 (bud), Steyermark & Agostini 91130 ( M I C H ) (hypanthium pubescent without). SURINAME. Wilhelmina Gebergte, Zuid Rivier above confluence with Lucie Rivier, elev 220-250 m, 20 Sep 1963 (bud), Irwin et al 55902 (MICH) (petioles not corky-rimose); Placer L'Awa, collected on a trip to L'Awa and Tapanahoni, 31 Oct 1918 {i\),B. W . [Gonggrijp] 4158 (U, type of A. tetramera), 4162 (U, paratype of A. tetramera). BRAZIL. Amapa: Rio Araguari, 3 Sep 1961 (bud), Pires et al 50692 (MICH) (calyx-lobes 5; petioles not corky-rimose). Para: Vigia, 30 Dec 1956 (fl). Black & Wurdack 18944 (MICH) (infl. sub-racemose; plant nearly glabrous). The following may represent distinct species, but would key out best to Myrcia decorticans; additional material of both is needed for a decision: BRAZIL. Para: Rio Muirapiranga, 50°38'-50°50' W , 2°33'-2°50' S, 8 Oct 1965 (fl). Prance et al 1569 (MICH) (dibrachiate hairs short-stalked, not sessile; petioles corky-rimose; buds probably calyptrate). F R E N C H GUIANA: Montague de Kaw, elev 220-270 m, 12 Dec 1954 (fl). Cowan 38745 (NY, M I C H ) (leaves obtuse or short-acuminate), 14 Dec 1954 (fl). Cowan 38817 (MICH, N Y ) (leaves as in 38745).

Distribution:Venezuela South America|