Bryobrothera tambuyukonensis H.Akiyama & Suleiman, 2015

Akiyama, Hiroyuki & Suleiman, Monica, 2015, A new species, Bryobrothera tambuyukonensis (Daltoniaceae, Bryopsida), from Sabah, Borneo Island, Phytotaxa 192 (1), pp. 13-23 : 18-21

Bryobrothera tambuyukonensis H.Akiyama & Suleiman , sp. nov. ( Figs. 4–23 )

Type:— MALAYSIA. Sabah: Tongod District, Sg. Imbak Forest Reserve , Block IID, ridge zone, 05°04′35.2″ N, 117°11′7.2″ E, 1300 m asl., 2 April 2014, M. Suleiman 5871 (holotype BORH; isotypes BM, HYO, L, MO, NY, SAN) .

Plants light green or yellowish brown except for shoot tips, and quickly turning to brownish yellow in herbarium specimens. Primary stems short, tightly attached to substrata, bearing a number of aerial secondary stems. Secondary stems densely tufted, 3–7 cm long, scarcely branching, ± complanate-foliate, blackish brown, opaque, thick-walled except for pale green younger portions at tips, ca. 0.2–0.3 mm in diameter, round in transverse section, without central strand; stem leaves arranged in 10 rows and ± complanate-foliate; leaves of upper portion often caducous and the stems becoming naked, with lower portions of stems covered with old leaves, often decayed to only costae. Pseudoparaphyllia linear-lanceolate. Axillary hairs ( Fig. 21 ) transparent, 3–6 cells long including a slightly differentiated single basal cell. Rhizoids mainly emerging from lower part of secondary stems, not restricted to around buds, reaching 7 mm long, sparsely branched, with intricately pinnately branched side branches; cells of main and side branches densely and minutely papillose. Asexual reproductive organs not found, but easily detached leaves may serve as vegetative propagules.

4, 6–8: M. Suleiman 5871 (Sg. Imbak; holotype). 5: M. Suleiman 3698 (Tambuyukon). 9–11: Stem leaves. 12: Upper half of a leaf; note the denticulate margins. 13: Midleaf marginal cells. 14: Midleaf juxtacostal cells. 15: Median laminal cells. 16: Leaf apex. 17: Leaf base. 18: Alar region with quadrate cells. 19: Transverse section of an aerial stem. 20: Rhizoids. (All from the holotype.)

Stem leaves oblong-lanceolate, distinctly narrowed at base, 2.2–3.2 × 0.6–0.9 mm, conspicuously undulate in upper portions of lamina when both dry and wet ( Figs. 4–7 ); margins plane, denticulate except for basal portion; marginal 1–2 cells slightly differentiated, longer than inner ones; costa single, reddish brown in color, subpercurrent, ending 2–3 cells below the leaf apex, protruding only on dorsal side, only with dorsal stereids. Laminal cells pale green at first, but soon turning deep reddish brown or brownish yellow by conspicuous deposition inside; juxtacostal cells much longer than median and marginal cells; upper laminal cells round to shortly elliptic, 7–15 × 5–8 μm, evenly thick-walled, smooth; median laminal cells elliptic to fusiform, sinuate, ± porose, 12–30 × 5–8 μm, evenly thick-walled, smooth, becoming shorter and smaller toward the margin; lower laminal cells elongate, distinctly porose, 20–40 × 5–8 μm, evenly thick-walled, smooth; alar region differentiated with a few short-rectangular to quadrate cells, pale green at first, turning deeply reddish brown.

Dioicous? Male plants and antheridia not found. Perichaetia lateral on secondary stems. Prefertilization perichaetial leaves ( Figs. 22–23 ) much smaller than stem leaves, linear-lanceolate, narrowed at base, 0.8 mm (innermost one)– 1.3 mm (outermost one) long, with single costa; margins plane, serrate except for the basal portion; laminal cells smooth, similar to those of ordinary stem leaves in shape but with narrower and longer cells at margin; alar cells differentiated. Archegonia ca. 10 per perichaetium, without paraphyses. Sporophytes unknown.

Other specimens examined: MALAYSIA. Sabah: Ranau District, Kinabalu Park, Mount Tambuyukon, Musang Camp (Km10) to the summit, 6°11’56.5”– 6°12’42.7”N, 116°39’41.4”– 116°40’53.1”E, 1450–1670 m asl., 14 August 2008, M. Suleiman & D. P. Masundang 3640 & 3690 (both BORH, KLU), 3687, 3690 & 3700 (all BORH, HIRO, KLU), 3702 ( BORH, HYO, KLU, SNP), 3704 ( BORH, HYO, KLU, NY, SNP): Tongod District, Sg. Imbak Forest Reserve, Block IID, ridge zone, 5 ° 04'56.0"– 5°04′35.2″N, 117 ° 09'16.3"– 117º11’7.4”E, 900–1300 m asl., 2 April 2014, M. Suleiman 5807 ( BORH), 5820 & 5824 (both BORH, SAN).

Habitat: Forming compact and dense tufts on trunks and branches of small trees and shrubs in mossy forests.

Distinguishing features: (1) epiphytic habit, (2) complanate foliation, (3) distinctly undulate upper lamina, (4) evenly thick-walled, porose, and smooth laminal cells, and (5) denticulate upper leaf margins.

Note 1: The rhizoid branching pattern of Bryobrothera tambuyukonensis resembles that reported in the genus Adelothecium bogotense ( Whittemore and Allen 1989) , that is, with intricately pinnately branched side branches. They are, however, not restricted around branch primordia as in the case of A. bogotense .

Note 2: Axillary hairs of B. tambuyukonensis are almost similar in size and the number of cells to those of B. crenulata and Benitotania elimbata . While they are shorter than those of Adelothecium bogotense [10 or more cells according to Norris & Robinson (1979) and illustrated by Buck (1998: p. 18)] and have a single basal cell, which is absent in axillary hairs of A. bogotense .

Note 3: According to our field observation, this species, although much larger and often brownish in color, has a habit similar to that of Benitotania elimbata . These two species grow in the same locality, as seen in Sungai Imbak Forest Reserve. It prefers small tree trunks in steep upper montane forests with high humidity, at elevations of 900–1700 m. A large population of this species was observed by a mountain stream in Sungai Imbak Forest Reserve.

Interestingly, this species was not found at the Silau-Silau Trail in the vicinity of the Headquarter office of Kinabalu Park or at the summit zone of Mount Alab where B. elimbata thrives. Neither of these sites is ultramafic.

Figures

FIGURES 4–8. Plants of Bryobrothera tambuyukonensis.

FIGURES 9–20. Bryobrothera tambuyukonensis.

FIGURES 21–23. Bryobrothera tambuyukonensis. 21: Axillary hair. 22: Perichaetial leaves. 23: Margin of inner perichaetial leaf. (All from the holotype.)