Dianema harveyi Rex 1891
Creators: name: Ronikier, Anna
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Protozoa
Mycetozoa
Myxomycetes
Trichiales
Dianemataceae
Dianema
Dianema harveyi

description: Dianema harveyi Rex (1891: 397)
Original species description (Rex 1891): —Sporangia sessile, generally rounded or cushion-shaped, flattened above, averaging about 1 mm in diameter, 0.35 mm in height, sometimes elongated and bent into an irregular horse-shoeshape, color gold bronze, with a metallic lustre. Sporangium walls membranaceous, thin, translucent, containing no trace of lime, rupturing irregularly. Capillitium and spores concolorous, being brownish-yellow in mass. Capillitium composed of numerous slender threads from 1.5 to 2 µm in diameter, not connected with each other, simple, without free branches but often forked two or three times near their origin or insertion, nearly parallel, taut, running from base to the top of the sporangium. Spores 8 µm in diameter, pale yellow under a microscope, delicately spinulose, but apparently smooth under medium power lenses.
Orono, Maine, F. L. Harvey.
Lectotype (designated here, MBT 10015616): —Orono, Maine, F. B. Harvey #23 b, 1890, 1042662!, barcode PH00002637 (Fig. 1A–G, 3).
Other original material (syntypes): Maine?, surely part of type sent to Morgan by Wingate, BPI746312! (Fig. 1I –J, 4); Maine, leg. F. L. Harvey, det. G.A. Rex —from Wingate coll., BPI746311! (Fig. 2A–C, 5); Maine, leg. F. L. Harvey, det. G.A. Rex —from Wingate coll., ex Univ. Iowa Myxomycete Collection, BPI746310! (Fig. 2 D – E, 6); Orono, Maine, leg. F. L. Harvey, L:B.M.168 (Fig. 1H).
Description of Dianema harveyi based on examined collections: —Sporophores scattered, sessile on a broad base, pulvinate, flattened above, copper-brown, effuse sporocarps or short plasmodiocarps, 0.70–1.36 mm long, 0.50– 1.3 mm wide and 0.20–0.46 mm high (Figs. 3A–B, 4A). Peridium slightly iridescent, single, dehiscing irregularly, the inner side slightly rough as seen by SEM (Figs. 3C, 4B). Capillitium rusty-yellow, not dense, straight, rigid, built up of parallel and dichotomously branched threads connecting the base of sporotheca and peridium, capillitial threads firmly attached to the peridium, smooth or rough (Figs. 3C–F, 4B–E). Spores rusty-yellow in mass, free, globose, very pale yellow as seen by compound microscope, 8–9.5 µm, av. 8.72µm, covered by irregularly distributed spines, baculate as seen by SEM, baculae with uneven apices, irregularly distributed (Figs. 3G, 4F).
Conclusions:— Among five syntypes of Dianema harveyi found at PH, BPI and BM, two were revised to represent that species, two others turned out to be a similar species, Prototrichia metallica and one (dry mount) has not been verified. The specimen stored at PH has been here designated for a lectotype of D. harveyi. This species differs from P. metallica by its flattened sporocarps, and completely smooth capillitium. Typically P. metallica has very characteristic penicillate capillitium with threads covered by spirals that are easy to observe under compound microscope. Importantly, the results of this study revealed that the characters of capillitium of P. metallica may sometimes be weakly developed; hence some specimens of P. metallica can be easily confused with D. harveyi. This is especially important in the light of the recently recognized very close phylogenetic relationships between these two species (Ronikier et al. 2020; García-Cunchillos et al. 2022). Therefore, a careful examination of capillitium characters together with shape of sporocarps is necessary to differentiate poorly developed sporophores of P. metallica from those of D. harveyi.
description: Published as part of Ronikier, Anna, 2023, Typification of the name Dianema harveyi (Dianemataceae), pp. 293-300 in Phytotaxa 620 (4) on pages 297-299, DOI: 10.11646/phytotaxa.620.4.5, http://zenodo.org/record/10080574