Pycnolejeunea grandiocellata Steph.

Promma, Chatchaba & Chantanaorrapint, Sahut, 2025, The genus Pycnolejeunea (Lejeuneaceae, Marchantiophyta) in Thailand, with the description of Pycnolejeunea zhuiana, PhytoKeys 259, pp. 145-160 : 145-160

2. Pycnolejeunea grandiocellata Steph. in Schmidt, Fl. Koh Chang, Bot. Tidsskr. 24: 279. 1902.

Figs 3 , 4

Type material.

Thailand. Trat: Klong Munse, 1899–1900, E. J. Schmidt 6 (holotype: G [ G 00128271]).

Description.

Plants whitish-green or light green when fresh, yellowish-brown or light brown in dry condition; shoots 0.80–1.23 mm wide, usually scarcely and irregularly branched; branches Lejeunea - type. Stems 76–99 µm diameter, in transverse section with 8–11 epidermal cells, surrounding 9–14 medullary cells, epidermal cells larger than medullary cells; cell walls pale brown or yellowish-brown, thick-walled, with triangular to bulging trigones, wall between trigones with thin to rather thick continuous thickenings; ventral merophyte 2 cells wide. Rhizoids at base of underleaves, few, tufted, usually hyaline, rhizoid disc not seen. Leaves imbricate, wide-spreading when moist. Leaf lobes ovate, oblong-ovate to oblong, 468–680 µm long, 376–487 µm wide, dorsal margin broadly arched, ventral margin slightly to strongly arched, margin entire, apex rounded, incurved. Lobe cells convex or weakly mammillose on dorsal side, thin-walled, with small to large triangular trigones, intermediate thickenings absent or occasionally seen in the marginal and basal cells; marginal cells rectangular or quadrate, 18.0–22.8 × 11.3–23.0 µm, median cells hexagonal to rounded, 18.0–38.3 × 19–24.8 µm, basal cells hexagonal to rectangular, 25.0–41.5 × 20.0–26.0 µm; ocelli rectangular to long hexagonal, 39.5–63.5 × 21.0–36.5 µm, 4–15 per leaf lobe, suprabasal, commonly aggregated, confined from base to the ventral half of leaf lobe; oil bodies not seen. Lobules small, oblong, 132–178 µm long, 90–109 µm wide, inflated, 0.16–0.30 of lobe length, free margin slightly involute, formed by 5–7 (– 9) elongated cells, apex semicircular or rarely truncate, apical tooth short, 1 - celled, obtuse, keel arched or nearly straight, lobule cells smooth or slightly convex. Underleaves contiguous to imbricate, sometimes slightly remote, suborbicular to subreniform, 116–297 µm long, 206–363 µm wide, wider than long, ca. 3 of stem width, bifid to 1 / 3–1 / 2 of its length, lobes triangular with acute to obtuse apex, margin nearly entire or bluntly toothed at side, sinus V-shaped, bases rounded to cuneate, insertion line arched. Asexual reproduction by unmodified caducous leaves, lobule remain attached to the stem. Sexuality autoicous. Androecia on short branches, terminal or intercalary on branches, inflated, spicate, 407–663 µm long, 452–607 µm wide; bracts in 2–4 pairs, densely imbricate, isolobous; bracteole 1–2, restricted at the base of the branch, bifid. Gynoecia on short branches, with 1 (– 2) subfloral innovations; bracts in one pair, subequal in size, bract lobes obovate, 733–829 µm long, 286–563 µm wide, apex rounded, incurved, margin entire; ocelli 10–26 per lobe or numerous, aggregated from base to the middle of the lobe; bract lobules lingulate to narrowly oblong, 449–503 µm long, 126–157 µm wide, 0.5–0.8 of lobe length, ca. 2 / 3 of the bract-lobe area, apex acute to obtuse, keel slightly arched, short; bracteole shortly connate with the bracts at the base on one side or rarely on both sides, ovate to obovate, 479–602 µm long, 253–295 µm wide, apex usually emarginate or slightly bifid, lobe acute, margin entire; perianths obovate, ca. 0.5 emergent beyond bracts or sometimes almost entirely covered by bracts, 687–825 µm long, 380–488 µm wide, inflated, 5 - keeled, keels smooth or crenulate, apex usually truncate, beak short. Seta articulate. Capsule valves 4, broadly spreading after dehiscence. Elaters 30 per capsule, marginal elaters 22, upper ends attached to valve margins, inner elaters 8, usually rudimentary, both ends attached to valve surface. Spores not seen.

Distribution, habitat and ecology.

Tropical Asia, Australia and Oceanic Islands ( He 1999; Yang and Lin 2011). In Thailand, Pycnolejeunea grandiocellata was found growing on tree trunks and branches in tropical lowland and submontane forests at 65–1200 m in elevation.

Taxonomic notes.

Pycnolejeunea grandiocellata is easily recognized by a combination of the following characters: 2 cells wide ventral merophytes, closely imbricate leaf lobes, numerous suprabasal ocelli which are commonly aggregated and the oblong leaf lobule with 5–7 elongated cells along the free margin. Pycnolejeunea grandiocellata resembles P. contigua in general appearance. For distinguishing characters of these two species, refer to the taxonomic notes section of P. contigua .

Specimens examined.

Thailand. Krabi: Hat Noppharat Thara - Mu Ko Phi Phi National Park, Khao Ngon Nak Mountain , 8°5.8267'N, 98°45.1067'E, 150 m elev., 24 Mar 2018, A. Senayai 21 ( BKF, PSU) ; 8°5.415'N, 98°46.1683'E, 380 m elev., 24 Mar 2018, A. Senayai 28 a ( BKF, PSU) ; 13 Oct 2018, A. Senayai 337 b ( BKF, PSU) ; 8°5.4'N, 98°46.1517'E, 452 m elev., 18 Feb 2019, A. Senayai 411 ( BKF, PSU) ; 8°5.4'N, 98°46.1517'E, 456 m elev., 12 Jun 2019, A. Senayai 416 ( BKF, PSU) ; A. Senayai 417, 418 a ( BKF, PSU) ; 8°5.8267'N, 98°45.1067'E, 96 m elev., 18 Feb 2019, A. Senayai 506 a ( BKF, PSU) ; Klong Thom, Sa Morakot (Emerald Pool) , 65 m elev., 9 Nov 2012, T. Pócs & S. Somadee 1227 / K ( EGR, PSU) .

Figures

Figure 3. Pycnolejeunea grandiocellata Steph. A. Portion of sterile plant, ventral view; B. Portion of fertile plant, ventral view; C, D. Transverse sections of stems; E – H. Lateral leaves; I. Cells from basal and near middle portion of leaf, dorsal view; J. Cells from apical leaf margin; K. Leaf lobule; L – O. Underleaves; P. Androecium; Q. Gynoecium; R. Perianth; S, T. Female bracts; U. Female bracteole. Drawn by C. Promma; based on T. Pócs & S. Somadee 1227 / K (PSU).

Figure 4. Pycnolejeunea grandiocellata Steph. A – C. Portions of sterile plants, ventral view; B. Showing underleaves; C. Showing ocelli; D. Portion of fertile plant, ventral view; E. Androecium; F. Gynoecium; G. Lateral leaf; H. Leaf lobule; I. Underleaf; J. Transverse sections of stem; K. Transverse section of leaf; L, M. Cells from basal portion of leaf, showing ocelli. Photographed by C. Promma; based on T. Pócs & S. Somadee 1227 / K (PSU).