Macromitrium yuleanum Broth. & Geheeb

Shevock, James R., 2015, Species of Macromitrium (Orthotrichaceae) New to the Mindanao Region and the Philippines with One Species New to Science, Proceedings of the California Academy of Sciences 62 (21), pp. 541-549 : 545

Macromitrium yuleanum Broth. & Geheeb

SPECIMENS EXAMINED:— Mindanao Island: Bukidnon Province: Mt. Kitanglad Range Natural Park, midslope of Mt. Dulan-Dulang Peak along the ridge trail separating headwaters of Alanib River and Magnao River , on fallen branch in mixed hardwood forest, 21–23 Apr 2014, Shevock 44727, 44779, 44842 ( CAS, CMUH, NY, UC) .

According to Vitt et al. (1995), this is the most common, large sized and variable species of Macromitrium at high elevation in Huon Peninsula of Papua New Guinea and has been described as a new species at least seven times. The Mindanao collections cited above fit well with the species description presented in Vitt et al. (1995). They differ mainly in having widely erectspreading (not squarrose-recurved) leaves when wet, more narrowly acuminate leaf apices, and a calyptra with noticeably stiff and long hair.

Macromitrium yuleanum is best identified by its narrowly ovate-lanceolate to oblong lanceolate leaves with percurrent to short, excurrent costa, and a weakly differentiated border of 1 to 2 rows of short rectangular, smooth cells near the denticulate apex and along the margins of the upper half of leaf. The laminal cells vary from mammillose to unipapillose. The setae are long, reaching more than 15 mm. The perichaetial leaves have a very long excurrent costa, nearly of the same length of lamina in some leaves.

Among the local congeners, M. longicaule Müll. Hal. is most similar in plant habit and leaf characters to Macromitrium yuleanum , but the former has percurrent leaf costa and short seta less than 5 mm long. Likewise, the somewhat look-alike M. macrosporum Broth. differs from M. yuleanum in having the percurrent leaf costa that ends at an incurved and entire apex. The leaf cells are nearly smooth and only slightly mammillose, but not unipapillose like in some leaves of Macromitrium yuleanum . The calyptra of M. macrosporum is also smooth with no hairs. Macromitrium yuleanum can also be mistaken for M. ochraceum , which is more commonly encountered in Mindanao Island. According to Eddy (1996), it can be separated from the latter by its less acute and shorter leaf apices with setae twice as long as that of M. ochraceum .

Macromitrium yuleanum was previously viewed as an endemic species of New Guinea and Solomon Islands.