Physcomitrium allardiae N. Wilding & Ah-Peng, 2025

Wilding, Nicholas & Ah-Peng, Claudine, 2025, Physcomitrium allardiae N. Wilding & Ah-Peng, sp. nov. (Funariaceae), a new species with immersed, cleistocarpic capsules from Tanzania, Cryptogamie, Bryologie 20 (2), pp. 9-13 : 10-12

Physcomitrium allardiae N. Wilding & Ah-Peng , sp. nov

( Fig. 1 )

DIAGNOSIS. — Physcomitrium allardiae N. Wilding & Ah-Peng , sp. nov. differs from all congeners in the combination of strongly bordered leaves, sub-spherical, non rostellate capsules, and spores with baculate-insulate surface ornamentation.

TYPE MATERIAL. — Tanzania • Uluguru Mts., North slopes of Bondwa , above Morogoro; high altitude Podocarpus - Allanblackia mist forest ; 1800-2500 m alt.; 13.XII.1970; leg. E.W. Jones & T. Pócs 6308/S (holo-, PC [ PC0723477 ]!) .

ETYMOLOGY. — The species is named in memory of Amandine Allard (1978-2023) a close friend and colleague of the authors. Amandine worked with enthusiasm as a technical officer at the Muséum national d’Histoire naturelle in Paris (PC) for 21 years, where she was responsible for assisting in the curation of the bryophyte collection and for welcoming visitors to the Paris herbarium. She contributed greatly in localizing and digitizing the bryophyte type specimens of the PC herbarium. Her hand written species names on the red type folders serve as a memory of her presence and her contribution at PC. During her time at the museum, Amandine developed the ability to recognize the hand writing of many historical bryophyte collectors and taxonomists, which was of immense help when curating historical material. Amandine was a kind and caring person, with a great sense of humour, she will be missed dearly by all who knew and worked closely with her.

ECOLOGY. — The type specimen is described as having been collected on soil in “ Podocarpus-Allanblackia mist forest”, at an elevation of 1800-2500 m. The type collection is almost entirely comprised of a dense humusy mat of small liverworts, c. 2.5 × 2.5 cm, among which a small number of plants of Physcomitrium allardiae N. Wilding & Ah-Peng , sp. nov. are present. The liverwort mat appears to comprise primarily Riccardia sp. , Lejeunea sp. and an unidentified Geocalycaceae .

DISTRIBUTION. — The species is known only from the type locality in the Uluguru Mountains of Tanzania.

DESCRIPTION

Plants small to medium, light-green.Stem reddish, to c. 1.8 mm high, branching multiple times by sub-perigonial innovation; rhizoids cerise. Leaves erect-spreading, slightly contorted when dry, oblong-obovate to spathulate, c. (1-)1.4-2.1(-3.5)×0.4-0.8(- 1.4) mm, plane to weakly concave, margin limbate, entire below, serrulate above, apex short-acuminate to attenuate, decreasing in size basally, perichaetial leaves bigger than perigonial leaves; cells of upper lamina isodiametric to oblong, pentagonal or hexagonal, 35-60(-70) ×25-35 µm; basal cells lax, oblong, more or less quadrate, 62-150(-188)× (15-)20-35(-43) µm; marginal cells narrower, thicker-walled, forming a border 1-3 cells wide; costa ending below apex.

Autoicous? Seta c. 0.2 mm long, straight, smooth, pale-yellow. Capsule erect, sub-spherical, inoperculate, c. 0.6-0.7 × 0.5- 0.7 mm, slightly wrinkled when dry, orange-yellow at maturity, lacking a well-defined neck; exothecial cells isodiametric 30-60 µm in diameter, in cross-section with non-thickened anticlinal walls; operculum absent, cleistocarpic; peristome absent; spores 25-30 µm, sub-spherical, baculate-insulate. Calyptra not seen.

REMARKS

Physcomitrium allardiae N. Wilding & Ah-Peng , sp. nov. is characterized by its sub-spherical, non-rostellate, cleistocarpic capsules, which are unique within the family. Other species of Physcomitrium with comparatively reduced sporophytes, i.e. Physcomitrium patens , Physcomitrium magdalenae , and Physcomitrium readeri Müll. Hal. all have capsules that are distinctly rostellate at the apex and not rounded as in P. allardiae . In East Africa, P. allardiae may co-occur with P. magdalenae , however, in addition to the difference in capsule shape, the two can easily be distinguished by their leaves (strongly bordered by longer, narrower, thicker-walled cells in P. allardiae vs weakly bordered by longer cells with unthickened walls in P. magdalenae ), and spore ornamentation (baculate-insulate in P. allardiae vs. densely spinulose in P. magdalenae ).

In the absence of genetic data, it is impossible to infer a close relationship with any of the afore mentioned species, i.e. those members composing a polyphyletic Physcomitrella , since they each appear to have independently evolved the same reduced phenotype ( Medina et al. 2019). Physcomitrium allardiae may yet prove to be another example of an independent reduction in sporophyte morphology.

The single known specimen of Physcomitrium allardiae was originally identified as Physcomitrellopsis africana by an unknown individual, and consists of fewer than ten plants of which only two of these have mature sporophytes. No duplicate specimens of the type collection could be located at EGR or in any of the other herbaria where Jones and Pócs would have distributed their exsiccatae.

Observations based on a single plant suggest that maturation of the perichaetia and perigonia may occur simultaneously. The sexuality of the species could not be definitively confirmed due to the extremely limited number of fertile plants, but observations suggest it to be autoicous. Its sexuality could, however, be more complex, as has been observed in some species of Entosthodon and Physcomitrium , where the terminal innovation that overtops the perigonium is synoicous and possibly protogynous, however, this state is difficult to confirm because archegonia tend to be fertilized early-on, inhibiting the development of antheridia ( Wilding 2015, 2017).

Figures

FIG. 1. — Physcomitrium allardiae N. Wilding & Ah-Peng, sp. nov. A, habit humid; B, habit dry (same plant as in A); C, habit dry; D, perichaetial leaf; E, leaf apex, showing the limbate, serulate margin; F, spores. All from the holotype. Scale bars: A-C, 1 mm; D, 500 μm; E, 100 μm; F, 30 μm.