Alwisia repens Leontyev, Schnittler, G. Moreno, S.L. Stephenson, D.W. Mitch. & C. Rojas, Mycologia

Lloyd, Sarah J., Leontyev, Dmytro, Vigus, Paula & Schnittler, Martin, 2024, Repent for Alwisia repens: emended descriptions of two species of Alwisia (Myxomycetes) thought to lack a capillitium, Phytotaxa 634 (3), pp. 289-300 : 292-294

Alwisia repens Leontyev, Schnittler, G. Moreno, S.L. Stephenson, D.W. Mitch. & C. Rojas, Mycologia 106(5):939 (2014) emend. Lloyd, Leontyev, Vigus & Schnittler Figs. 2–4 .

Fructifications 1–3 mm high, composed of 10–100 sporocarps, with sporothecae typically forming dense clusters ( Figs. 2D, E ), often in large colonies ( Fig. 2F ). Hypothallus membranous, orange-brown, common for a group of sporocarps ( Fig. 2D ). Stalks erect or inclined and sinuous, reddish brown, with occasional dark brown sections, 1–2.5 mm long. The individual stalks arise from a short (0.3–0.5 mm) or sometimes longer compound stalk bearing a cluster of sporothecae ( Figs. 2D–F ); they are flexuous, irregularly gyrose, and branch occasionally ( Fig. 2I ). Sporothecae beige, pinkish or brownish ochraceous, 1.0– 1.7 mm long, 0.5–0.9 mm in diam, more or less similar in size within a colony, short cylindrical to obovoid, with rounded upper part and conical base; free or attached to each other at widest parts ( Figs. 2E, F ). Basal part of the peridium brown, membranous, iridescent with pink, green and golden colors, somewhat plicate ( Fig. 2F ). Upper part of the peridium light beige to light brown, mottled, formed by 0.1–0.2 mm wide, rounded to angular platelets that easily break apart at dehiscence ( Figs. 2G, H ). Peridial platelets transparent, iridescent reflecting blue, golden, and pink colors ( Figs. 2K–O ); often with a dark central spot ( Figs. 2G, H ); almost hyaline in transmitted light, with brownish central area, often bearing vestigial capillitium structures looking like short tubules ( Figs. 3A–D ) or convexities that appear on a microscope slide as a group of crescent-shaped folds ( Figs. 3E–I ). Capillitium vestigial but occurring in most of sporothecae, forming very short, smooth, brown, cylindrical tubes or grooves on the inner surface of peridial platelets ( Figs. 2N , 3A, B ) attached to the peridium at the ends or along the entire length ( Figs. 2O , 3C ); visible from the outside as brownish spots, lines, and pits ( Fig. 2H ). Spore mass beige to ‘coffee with milk’ ( Fig. 2G ). Spores light brownish in transmitted light, (5.7–)6.0–6.9(–7.3) mm diam, banded-reticulate but nearly always with a smooth area. Dark red circular droplets the same size or slightly larger than the spores are found in the spore mass ( Fig. 3D ). Plasmodium translucent. Immature fructifications translucent, later creamy white, then dark brown, and finally beige when mature. At the white stage, dark grey-brown bodies occur inside the sporothecae ( Figs. 2A , 4A–C ). The stalks of immature sporothecae are initially white, later yellowish, then orange brown and finally red brown when mature; stalks are coalescing when immature but mostly breaking apart when dry ( Figs. 2D–F ).

Material examined. Six collections, including the isotype, one field observation and 12 records, published online (see Supplementary file 1).

Habitat and distribution. Fructifications are often densely clustered, forming patches up to 50 mm long, usually on well decayed logs or stumps in wet sclerophyll forests or rainforests in south eastern Australia, including New South Wales, Victoria and Tasmania ( Fig. 6 ). Mature sporocarps can remain in the field in sheltered locations for more than a year. The collection SJL2167 dated 27 March 2022 is still in the field (13 Sept 2023), albeit covered by a fungal mold. The original description (p. 942) mentions the substrate as ’decaying wood and litter of deciduous trees’. This was imprecise: the tree was a Eucalyptus sp. , and the litter was sclerophyllous, probably also Eucalyptus sp.

Note. The discovery of previously unknown structures in A. repens , including peridial platelets and vestigial capillitium, inspired us to search for similar elements in another species, A. morula , which was described simultaneously with A. repens and was also characterized by the complete absence of capillitium ( Leontyev et al. 2014a). The study of the isotype of this species shows that it does indeed have peridial platelets, but they are less noticeable and occupy only part of the upper surface of the sporotheca. Vestigial capillitium elements in A. morula are less abundant, but more developed than in A. repens and may extend from the top to the base of the sporotheca. Below we provide a revised description with an emphasis on the newly identified structures. Quantitative characters are taken from the original diagnosis.

Figures

FIGURE 2. Fruiting bodies of Alwisia repens. A–C. Developing sporocarps. D–E. Freshly mature sporocarps. F. Mature sporocarps showing stalks at the base. G, H. Upper surface of closed sporothecae, showing peridial platelets. I. Sinuous stalks. J. Opened sporothecae forming a layer. K–M. Peridial platelets on upper part of the peridium. N. Tubule of vestigial capillitium (arrow) formed on a peridial platelet. O. Tubule of vestigial capillitium (arrow) parallel to the surface of a peridial platelet. Bars: A–G, I, J. 0.5 mm. H, K–M. 100 μm. N, O. 50 μm. Specimen: SJL2167. Photo authorship: A–H. SJL; I–O. DL.

FIGURE 3. Fruiting bodies of Alwisia repens under transmitted light. A. Sporotheca with upper part formed by peridial platelets, capillitium tubules (white arrows) and pits (black arrow). B, C. Vestigial elements of capillitium. D. Reddish brown oil droplet next to a rudimentary capillitium tube. E, F. Peridial platelets with pits flattened by coverslip. G–I. Details of peridium with flattened pits and folds. Bars:A. 500 μm. B. 100 μm. C–F. 50 μm. Specimen: SJL2167.Material inA, B, C, F is stained by Methyl Blue diluted in lactic acid.Photo authorship: A–C, F. DL; D, E, G–I. SJL.

FIGURE 4. Developing sporocarps of A. repens (A–C) and A. lloydiae (D). Dark bodies are seen in A. repens, but not in A. lloydiae. Bars: 0.5 mm. Specimens: A–C. Observation Web 01; D. SJL not collected. Photo authorship: A–C. PV; D. SJL.

FIGURE 6. Distribution of Alwisia repens according to available data (Supplementary file 1). A. All known occurrences. B. Occurrences in mainland Australia and Tasmania. C. Locality in New Zealand. The yellow dot indicates the type locality; all other localities are marked with red dots.