Acrobolbus mashpianus Burghardt, 2022

Burghardt, Michael, 2022, Acrobolbus mashpianus (Acrobolbaceae, Marchantiophyta) sp. nov. from the Northern Andes of Ecuador-Notes on the Bryophytes of Ecuador VII, Phytotaxa 577 (1), pp. 133-138 : 133-134

Acrobolbus mashpianus Burghardt , sp. nov. ( Fig. 1 )

Diagnosis:— Acrobolbus mashpianus is similar to Acrobolbus setaceus in its toothed leaf margins but differs by the strongly asymmetrically bilobed leaves that are more deeply bifid (1/2–4/5 vs. 1/4–1/3) and the longer teeth of the leaf margin (5-8 cells vs. 1-3 cells long).

Type:— ECUADOR. Pichincha: Metropolitan District of Quito, Parrish Pacto, Mashpi Ecological Reserve , Jungle Swing trail, elev. 913 m, 0°09’58.13’’N 78°52’50.36’’W, 22 February 2019, M. Burghardt MB 11033 (holotype: QCNE!).

Plants prostrate, scattered among other bryophytes; soft-textured, whitish green, turning brownish in the herbarium. Shoots small, up to 1.5 cm long and 1.3–1.5 mm wide with leaves; microphyllous stoloniferous base lacking. Stems light brown, slightly dorsoventrally flattened; near base ca. 85–140 × 60–100 µm thick, in cross-section about 4–6 cells high; differentiation in cortex and medulla lacking, cells thin-walled, ca. 10–23 × 11–17 µm, without trigones or only tiny ones; stem surface papillose to striate-papillose. Branching sparse, lateral-intercalary of the Plagiochila - type; rhizoids scattered along the stem. Shoots with contiguous to subimbricate foliation. Leaves succubous, obliquely to widely spreading, plane; ventral leaf margin not decurrent; dorsal margin not to shortly decurrent by few cells; leaves cuneate to occasionally subrectangular, widest above the middle, asymmetrically bilobed to 4/5, occasionally only to 1/2, with the dorsal lobe distinctly smaller than the ventral lobe; ca. 450–720 × 270–400 µm, 1.5–2.4 times as long as wide; lobes elongate triangular to lanceolate, acuminate, margins plane and crenulated, especially towards the (2–)4– 7(–8)-celled uniseriate lobe tips; lobes usually widely diverging, sometimes subparallel to somewhat connivent. Leaf margins beset with one to four elongate triangular to more commonly ciliate teeth, teeth 5–8 cells long, consisting of a short 2-celled base and a 4–7 cell long uniseriate tip. Leaf areolation ± regular; cells in the center of the ventral leaf lobe isodiametric to distinctly elongated with scattered cells shorter than wide, (30–)35–42(–52) × (29–)30–38(–47) µm, (0.9–)1.1–1.4(–1.8) times as long as wide; cells of the lobe tips (uniseriate part) slightly elongated, (29–)30–35(– 40) × (20–)22–24(–26) µm, (1.1–)1.2–1.5(–1.7) times as long as wide; cell walls thin, trigones small, triangular with convex sides, intermediate thickenings absent, leaf surfaces striate-papillose with some papillae rounded. Oil bodies of the Jungermannia - type, brown, 4–6 per cell, ellipsoidal to sometimes globose, surface granular. Underleaves vestigial, one-to-two-celled. Asexual reproduction possibly by fragmenting leaf lobes and teeth.

Male and female plants were not seen.

Habitat and distribution:— Acrobolbus mashpianus is only known from the type collection from the Mashpi Ecological Reserve in the Province of Pichincha. For a detailed description of the locality see Burghardt (2020). The holotype was collected in a humid evergreen premontane forest, where it grew on a tree trunk in appressed mats of a rich liverwort community. Associated species include Ceratolejeunea cornuta ( Lindenberg 1829: 23) Stephani (1895: 65) , Leptoscyphus trapezoïdeus ( Montagne 1843: 251) Söderström (2013: 27) , Plagiochila rudischusteri Robinson (1988: 199) , Prionolejeunea aemula ( Gottsche 1845: 338) Evans (1904: 219) , P. muricatoserrulata ( Spruce 1884: 155) Stephani (1913: 223) , and P. trachyodes ( Spruce 1895: 338) Stephani (1913: 215) .

Etymology: — The name of the new species refers to the type locality.

Figures

FIGURE 1. Acrobolbus mashpianus. A. Part of shoot, dorsal view. B. Part of shoot, ventral view. C. Underleaf, in situ. D. Cells from center of ventral leaf lobe with oil bodies. E. Cells from center of ventral leaf lobe, leaf surface papillae indicated. F. Detail of Plagiochila- type branch, ventral view. G.-J. Leaves. K. Stem cross-section. All drawn from MB 11033 (QCNE).