Tryssophyton merumense Wurdack, Mem. New York Bot. Gard. 10: 155. 1964.

Wurdack, Kenneth J. & Michelangeli, Fabian A., 2019, Systematics and relationships of Tryssophyton (Melastomataceae), with a second species from the Pakaraima Mountains of Guyana, PhytoKeys 136, pp. 1-21 : 1

Tryssophyton merumense Wurdack, Mem. New York Bot. Gard. 10: 155. 1964.

Type.

Guyana. Cuyuni-Mazaruni Region, Partang River, Merume Mtns., Merume Mt.; common on mossy logs in forest, 1140 m elev., 4 Jul 1960 (fl., fr.), S.S. Tillett, C.L. Tillett, & R. Boyan 43988 (holotype: US-2343844!; isotypes: K-000329332!, NY-00245868!).

It should be noted that both the US and NY sheets are each marked as the holotype. However, the protologue clearly states that the US specimen is the holotype, even citing the sheet number and has that designation in J. Wurdack’s handwriting. The NY sheet has “holotype” merely typed on the label. Thus, there is no need to lectotypify this name and the NY specimen should be considered as an isotype.

Etymology.

The genus is combined from tryssos (Greek, dainty or delicate) and phyton (Greek, plant) and refers to the plant habit. The specific epithet refers to Merume Mountain where the type was collected.

Additional collections examined.

Guyana. Cuyuni-Mazaruni Region: Pakaraima Mountains, upper Karowrieng River at Maipuri Falls; mixed bryophyte, pteridophyte, herb community; sandstone boulders, white sand, large cave behind falls, 5°41'N, 60°13'W, 575-600 m elev., 13 Oct 1992 (fl.), B. Hoffmann 2939 (NY!, US!). 2nd and 3rd escarpments (of four) of Kamakusa Mt., upper west-facing slopes below summit, rich forest with Licania , Ebenaceae , tree ferns, Arecaceae , 5°52'55.2"N, 60°6'34.5"W, 1330 m elev., 8 June 2012 (fl., fr.), K. Wurdack 5870 (US!). Potaro-Siparuni Region: Mt. Wokomung, easternmost pinnacle of massif, scrub forest on sandstone and peat, with Guadua , Euterpe , and Sphagnum , 5°5'34.4"N, 59°50'13.3"W, 1524 m elev., 13 Jul 2003 (fl.), H.D. Clarke 10822 (NY!, US!). Mt. Ayanganna, east slope, plateau above second escarpment, growing on mossy tree trunks and roots, 5°22'28"N, 59°58'06"W, 1340 m elev., 16 Mar 2014 (fl.), A. Radosavljevic 165 (US!).

Distribution and ecology.

The five collections of T. merumense span a 90 km section of the central Pakaraima Mountains, but further exploration is likely to expand its range into similar habitats. The species was only recently discovered (Radosavljevic 165) on the slopes of relatively well-explored Mount Ayanganna, the highest mountain (2041 m) wholly within Guyana. At mid-elevations on the western slopes of Kamakusa Mountain, it occurred (Wurdack 5870) as scattered, rarely-reproductive individuals on rotting logs and peaty-humus zones around the bases of trees.

The mountainous area north of the village of Imbaimadai and including Kamakusa Mountain has been variously mapped as the Merume Mountains. However, exactly what corresponds to the peak "Merume Mountain" within the region and indicated as the type locality of T. merumense , is unclear. Field notes (Bassett Maguire Field Collections, vol. 19, Archives of The New York Botanical Garden) reveal that during 11 Jun– 16 Jul 1960, after leaving Imbaimadai, the collecting team, led by Stephen Tillett entered the Kamakusa Mountain area from along the Partang River. After reaching Partang Falls, they ascended into the uplands following existing trails, which were probably made by gold-miners or “pork-knockers.” It is likely that "Merume Mountain" of Tillett et al. is equivalent to Kamakusa Mountain, but details referring to lower elevations, southeast ridge, southeast side and cliffs do not indicate they reached summit where T. quadrifolius was collected.