Dictyocheirospora tetraploides (L. Cai & K.D. Hyde) J. Yang & K.D. Hyde
Index Fungorum number: 554776
Etymology: "tetraploides", referring to the similarity of these conidia to those produced by species of the genus Tetraploa.
Sporodochia on natural substratum 180–310 µm diam, punctiform, scattered, black, granular. Mycelium mostly immersed, composed of brown, smooth, thin-walled, septate, branched hyphae. Conidiophores micronematous, mononematous, hyaline, smooth, thin-walled, septate, branched, cylindrical, short, deteriorating at conidial maturity. Conidiogenous cells monoblastic, integrated, subhyaline to hyaline, smooth, thin-walled, cylindrical, cuneiform, determinate. Conidial secession rhexolytic. Conidia 52.5–72.5 × 18.5–26.5 µm (x̄ = 63 × 22 um, n = 25), cheiroid, cell rows arranged in several layers, medium brown, becoming dark brown with maturity, smooth, euseptate, holoblastic, cylindrical to clavate, corn-shaped, consisting of 48–57 cells arranged in 5 rows. Rows compact, not separating, arised from a 4–6 µm wide, subhyaline to hyaline, cubical, truncate basal cell. Each row of cells 6–7 um wide, consisting of 9–12 cells, terminating in an incurved hook. The subapical cells of the outer rows are provided with an appendage which is hyaline, thin-walled, cylindrical to clavate, membrane borne, unicellular, measuring 10–25 × 5–10 µm. Mostly 2 appendages on each conidium. These rows of cells are tightly appressed together as a cylinder and separate only under pressure. (Description from Cai et al. 2003)
Holotype: CHINA. Yunnan, Xishuangbanna, Menglun, a small stream, on submerged wood, 21 June 2002, L. Cai (HKUM 17146).
Culture characters: Colonies on CMA reaching 2 cm diameter after 1 week at room temperature (~ 23 C), fully appressed, margin entire, white, reverse white. Hyphae 2–3 µm wide, hyaline, septate, branched and smooth-walled, sterile after 3 months incubation.
Dictyocheirospora tetraploides is morphologically similar to Di. musae in conidial shape, size, colour and appendages. However, conidia of Di. tetraploides have 5-rowed cells, while those of Di. musae are 7-rowed cells (Photita et al. 2002, Cai et al. 2003).
Freshwater distribution: China (Cai et al. 2003)
Cai L, Zhang KQ, McKenzie EHC, Hyde KD (2003) New species of Dictyosporium and Digitodesmium from submerged wood in Yunnan, China. Sydowia 55:129–135
Photita W, Lumyong P, McKenzie EHC, Hyde KD, Lumyong S (2002) A new Dictyosporium species from Musa acuminata in Thailand. Mycotaxon 82: 415–419.
Figs. 6-11. Interference contrast micrographs of Dictyosporium tetraploides (from holotype). 6, 7. Squash mount of sporodochium with conidia, 8-11. Conidia with appendages (arrowhead) and basal cells (small arrows), 11. Conidium only show 5 arms divergent when under pressure. Scale bars: 6, 7 = 40 µm; 8-11 = 20 µm. (Cai et al. 2003)