Bazzania calypogeoides Bakalin, Maltseva & Klimova

Bakalin, Vadim, Maltseva, Yulia, Klimova, Ksenia & Ma, Wen Zhang, 2024, Bazzania calypogeoides (Marchantiophyta) - a peculiar new taxon from Eastern Hengduan (China), Phytotaxa 645 (3), pp. 214-231 : 221-227

Bazzania calypogeoides Bakalin, Maltseva & Klimova sp. nov.

Description: Plants creeping to loosely ascending, pale green in loose pure patches or with sparse admixture of Anastrepta (Lindberg in Lindberg & Arnell 1889: 40) Schiffner (1893: 85), 1.5–1.8 mm wide and 10–20 mm long. Rhizoids not seen. Stem freely pseudodichotomously branched; ventral flagellae sparse (when present, without rhizoids); cross section rounded to slightly transversely ellipsoidal, 250–270 × 270–300 µm, external wall thickened (thinner on ventral side than on dorsal one), outer cells subquadrate to 5–6-gonal, 28–32 µm in diameter, thin-walled (except the outer wall), with concave trigones, moderate in size, inward cells 20–35 µm in diameter (slightly smaller in average size in comparison with outer cells), thin-walled or walls slightly thickened especially in dorsal third of cross section, polygonal, with concave, small to moderate trigones. Leaves contiguous to shortly imbricate (overlapping a short distance), obliquely inserted, dorsally insertion line curved to subtransverse; leaves strongly convex, turned to ventral side in upper halves (both in dry and moist conditions); when flattened on the slide commonly torn, triangularovate, 900–1100 µm long and 850–1000 µm wide, with apex shortly divided into two small unequal lobes (dorsal longer), margin entire. Cells along leaf margin subquadrate to 5–6-gonal, 10–15 µm in diameter, walls thin to thickened, trigones moderate in size to large (following Bakalin 2014: 69 “large – the distance between trigone to the nearest one is less than diameter of trigone, moderate – the distance between one trigone to the next is more than trigone diameter, but less than triple the diameter of the trigone”), mostly concave, rarely slightly convex, external wall thickened; midleaf cells subisodiametric to shortly oblong, 16–25 µm in diameter or 20–30 × 16–25 µm, thin-walled, moderate in size, concave trigones; small zone of large cells is present near leaf base; cuticle smooth throughout. Underleaves obliquely spreading (ca 40° with stem axis), 1.5–2.0× as wide as stem, free or connate with leaf on one side, shortly decurrent, transversely ellipsoidal to widely lingulate, with entire margin and apex shallowly emarginate or with 2–4 indistinct lobes (giving the apex the appearance of being crispate), when flattened on a slide 400–500 × 550–700 µm. Generative organs unknown ( Figures 3 , 4 ).

Holotype:— CHINA. Yunnan Province: Lijiang Municipality, Yu-Long County, Jiu-He Xiang , 99- Dragon Pool Scenic Area. Crooked forest of evergreen Rhododendron Linnaeus (1753: 392) and other scattered trees along ridge. Partly shaded moist fallen decaying tree trunks, 26.64297°N 99.75469°E, 3590 m a.s.l., 13 October 2018, V.A. Bakalin & W.Z. Ma C-77-29-18 (VBGI).

Paratypes:—Same locality as above, 13 October 2018, V.A. Bakalin & W.Z. Ma C-77-36-18 ( VBGI). CHINA. Yunnan Province: Dali Prefecture, Chuan County, Yang-Cen Xiang , ridge line of Lao-Jun-Shan Range. Forestless landscape (grassland significantly damaged due to sheep over-grazing) with some rocky outcrops and shrubby clumps. Mesic humus in partial shade, 26.59881°N 99.76617°E, 3515 m a.s.l., 11 October 2018, V.A. Bakalin & W.Z. Ma C-74-1-18 ( VBGI). Sichuan Province: Zheduotangcun area . The valley of a small stream with Abies Miller (1754: 1) , Betula Linnaeus (1753: 982) and Rhododendron forest. Moist decaying wood in part shade, 29.97600°N 101.88600°E, 3678 m a.s.l., 14 October 2017, V.A. Bakalin & K.G. Klimova C- 41-5-17 ( VBGI). Sichuan Province: Kangding airport area . SW-facing gentle slope of the range, covered with communities like hummocky tundra with low Rhododendron and Pentaphylloides Duhamel (1755: 99) ; shallow gully with banks of large rocky blocks and Rhododendron and Juniperus Linnaeus (1753: 1038) shrubs between. Partly shaded, moist crevices between large blocks, 30.11500°N 101.77700°E, 4420 m a.s.l., 14 October 2017, V.A. Bakalin & K.G. Klimova C- 44-9-17 ( VBGI) .

Etymology. The species is named due to its superficial morphological similarity to Calypogeia , especially Calypogeia suecica (Arnell & Persson in Arnell 1902: 29) Müller (1904: 224), C. sinensis Bakalin & Buczkowska (in Buczkowska et al. 2018: 13) and some other Calypogeia taxa.

Discussion

Differentiation

As the name implies, the plants closely resemble Calypogeia especially the C. sinensis – C. lunata Mitten (1860: 107) group, as well as C. suecica , due to the shortly incised leaf apices turned to the ventral side. The similarity is enhanced by a rarity of ventral stolons, so characteristic for the vast majority of Bazzania representatives. These features are seen at the macro level, and a more careful study at the micro level immediately reveals the significantly small size of the leaf cells, pachydermous leaf cell network feature ( Figure 4 : C, H, I), and the absence of a small-celled rhizogenous zone at the base of the underleaves, which attributes the plants to the genus Bazzania , not Calypogeia . However, some “ Calypogeia -like” characters may be mentioned here because they differentiate the species from many other Bazzania . First, the transversely ellipsoidal, slightly emarginate to vaguely 4-lobed underleaves ( Figure 3 : G, H, I; Figure 4 : J, K), are reminiscent of those of Calypogeia japonica Stephani (1924: 448) or even C. integristipula Stephani (1908a: 662) . Secondly, the leaves are broadly ovate with a short incision at the apex.

Although several species of Bazzania in eastern Asia and adjacent areas of Southeast Asia have distinctly bilobed leaves and cholorophyllose, emarginate or short-lobed underleaves ( B. bidentula ( Stephani 1894: 222) Yasuda (1911: 711) , B. bicrenata Kitagawa (1980: 127) , B. parabidentula Bakalin (2016: 35)) , all are clearly distinguished by their much narrower leaves compared to the taxon described here. We did not find any species similar to the one described here from China and adjacent regions. Similar taxa exist only occur at a greater distance.

One similar taxon, Bazzania fallax ( Sande Lacoste 1864: 304) Schiffner (1898:158) (distributed from Malesia to Australasia), resembles B. calypogeoides due to its broadly ovate leaves. However, B. fallax differs from the described species in brown pigmentation (versus green plants with or without very weakly expressed secondary pigmentation), significantly larger cells in the middle part of the leaf, reaching 32–40 × 28–30 µm ( Meagher 2010), very large nodulose trigones of leaf cells, the presence of additional teeth near the leaf apex and rather deeply lobed underleaves.

We have found the most similar to the new taxon to be Bazzania wooroonooran Meagher (2015: 549) , so far known from Queensland in Australasia and New Caledonia in eastern Melanesia ( Meagher 2019). This species differs from B. calypogeoides in 1) entire underleaves, often with a narrowly revolute apex (versus a emarginate to vaguely lobed underleaf apex, which is never revolute), 2) a large magno-cellular zone constituting most of the inner part of the leaf (versus the very small extent of such a zone in the leaf base of B. calypogeoides ), 3) larger cells of the middle part of the leaf, reaching 25–40 × 20–28 µm with large bulging trigones (versus 20–30 × 16–25 µm, thin-walled cells, with moderate,, concave trigones, Figure 4 : F, G), 4) pale brown coloration of plants, versus pale green plants ( Figure 4 : A, B, D, E).

Of the phylogenetic trees based on rbc L and trn L-F sequences, Bazzania calypogeoides appears to be most closely related to several species: 1) Bazzania sikkimensis , also characterized by bilobed leaves, but distinguished by a narrower leaf shape, more deeply lobed leaves, and dentate underleaf apices. 2) the complex Bazzania praerupta — B. pearsonii — B. ovistipula which are all characterized by three-lobed leaves and large nodular trigones of leaf cells (except for the typical forms of B. ovistipula ). Moreover, the underleaves in all three are either entire, shallowly emarginate, or crispate and never transversely ellipsoidal.

As a result of our fragmentary collections from the Chinese Sino-Himalayas, the species was identified in 5 specimens from two provinces, which seems to indicate that it is more widespread in that area. Could this species be hidden in the Chinese Bazzania treatment by Zhou et al. (2012b)? A look at the figures and descriptions in the mentioned paper suggests that specimens referable to Bazzania bidentula in Zhou et al. (2012b) may actually be Bazzania calypogeoides . Photographs C, F, G (figure 8 in l.c.), taken from one specimen (M.Z. Wang 5967, PE), most likely belong to B. calypogeoides , and not to B. bidentula , to which they were assigned. The type specimen of the latter was discussed in Bakalin (2016) and it differs from B. calypogeoides in having significantly narrower, highly caducous leaves, papillose cuticle and a distinct secondary (brown) pigmentation.

Ecology

All specimens were collected at elevations from 3515 to 4420 m above sea level. Conditionally, all locations are situated near the transition zone of mountain boreal forests — mountain treeless (tundra-like) landscapes. Three specimens were collected in the forest belt. This is a valley of small streams with Abies , Betula and Rhododendron forest, and a crooked forest of evergreen rhododendrons and other scattered trees along the ridge. The fourth sample (C-74-1-18) was collected above the forest zone, however, it is highly likely that the treelessness in that case may be secondary and due to overgrazing by farm animals. This is a grassland strongly damaged with some rocky outcrops and shrubby clumps. The fifth sample (C-44-9-17) was collected approximately 500 meters in elevation above the tree line (the area is described in detail by Bakalin et al. (2022a), as the locality of Gymnomitrion sichuanicum Bakalin & Vilnet ( Bakalin et al. 2022a: 123) . This is a tundra-like community with low Rhododendron and Pentaphylloides shrubs. The species was collected in the shallow gully with banks of large rocky blocks and Rhododendron and Juniperus shrubs between. In general, we characterize the species as oro-boreal, although extending beyond the upper limits of the forests.

Three specimens were collected on decaying wood, but the species is not an obligate epixylous taxon. Two more specimens were collected on partly shaded, moist crevices between large blocks and mesic humus in partial shade. Apparently, an important requirement of the species is relatively stable humidity; it is unlikely that the species can tolerate a prolonged drying out period (which also, in an ecological sense, makes the new taxon similar to Calypogeia ).

According to the obtained bioclimatic indicators for the collection sites ( Table 4 ), the habitats are characterized by the following climatic conditions: The average annual temperature is usually above and to less extent below the freezing point. At the same time, the minimum temperatures of the coldest month are always below zero, reaching - 16°C at the highest point. Annual precipitation varies from 755 to 868 mm per year. The warmest and wettest quarters coincide and the amount of precipitation (in liquid form) ranges from 396 to 425 mm per quarter. The coldest and driest quarters coincide in most cases or almost completely overlap. The amount of precipitation (exclusively or almost exclusively in solid form) during this period is very low, ranging from 11 to 64 mm. Temperatures during this period are negative (up to -10°C), only at the lowest point the temperature is slightly positive and is a little more than 1°C. The mean temperatures of the warmest quarter are not high and vary from 7 to 13°C. Such parameters are quite characteristic of the boreal zone due to high elevations.

Potential distribution

The species is known from four localities (two specimens were collected in one locality), all of which are located on the eastern border of the Hengduan mountain system. Considering that our experience in these areas is quite limited, the repeated collecting of this species indicates its possible regular distribution in that area. In general, we tentatively attribute the species to the eastern elements of the Sino-Himalayan flora. There are a number of taxa with a similar distribution. For example, Gymnomitrion sichuanicum , Plagiochila xerophila Bakalin et Vilnet (2020: 127) , Mesoptychia chinensis Bakalin, Vilnet & Xiong ( Bakalin, Vilnet & Xiong 2015: 196) , Konstantinovia pulchra Bakalin et Fedosov ( Bakalin et al. 2021a: 10) , Marsupella praetermissa Bakalin & Vilnet ( Bakalin et al. 2022b: 8) . Although all the above are known so far from one location it is hardly possible to draw far-reaching conclusions, with the accumulation of additional information, the predicted type of distribution will be preserved. The same is with Bazzania calypogeoides , in addition to its relatively wide distribution in the eastern part of the Hengduan mountain system, it may also be found in other areas of the eastern Sino-Himalayas.

Figures

FIGURE 3. Bazzania calypogeoides Bakalin, Maltseva & Klimova sp. nov.: A—Shoot, fragment, ventral view; B–E—leaves; F—I— underleaves; J—stem cross-section; K—plant habit, fragment, ventral view. Scales: a—2 mm, for A; b—1 mm for B–I; c—100 µm for J; d—4 mm, for K. All from C-77-29-18 (VBGI) Illustrations by M. Bakalin.

FIGURE 4. Bazzania calypogeoides Bakalin, Maltseva & Klimova sp. nov.: A— part of mat; B—part of mat; C—cells with oil bodies in leaf apex; D, E— shoot, fragment, dorsal view; F, G— leaves (torn under the cover glass in the slide); H— midleaf cells with oil bodies; I— cells with oil bodies in underleaf apex; F, G— underleaves. Scales: 5 mm, for A, B; 2 mm for D, E; 100 µm, for C, H, I; 500 µm, for F, G, J, K. A, C, D, F, G, J, K from C-74-1-18; B, I from C-41-5-17, E, H from C-44-9-17 (VBGI). (Photos by V. Bakalin, 2018, 2019.