Freshwater Ascomycetes - Species Monograph

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Genus	Species	Author
Echria	gigantospora	(Raja & Shearer) Kruys, Huhndorf and A.N. Mill. comb nov.
Class	Order	Family
Sordariomycetes	Sordariales	Lasiosphaeriaceae

Genbank ID: 565291 MycoBank ID: 500930

Synonymy:

Description

Habit:

Superficial to partially immersed on submerged, decorticated wood.

Ascomata:

Ascomata on wood 760–970 x 415–560 µm, superficial to partially immersed, subiculate or not, tomentose, scattered, obpyriform, ostiolate, membranous.

Peridium:

Peridium 30–35 µm thick, pseudoparenchymatous in surface view, semitransparent; in longitudinal section, peridial wall 2-layered, inner layer composed of 2–3 rows of elongated, flattened, thin-walled, hyaline to brown cells; outer layer composed of 3–4 rows of brown thin-walled angular cells 10-20 x 3-5 µm wide.

Beak:

Neck 150–200 x 78-98 µm, cylindrical to conical, opaque, black, inside lined with hyaline, filiform periphyses, covered with pointed, unbranched, tapering, long tufts of agglutinated, rigid, septate, cylindrical, brown hairs measuring ca. 100–500 µm long and 2 µm wide, occurring at an angle of 30–45° to the peridium.

Hamathecium:

Paraphyses hyaline, filiform-ventricose, 100–120 µm long, ca. 10–12 µm wide at the base, 3–4 µm wide at the apex, septate, abundant.

Ascus:

Asci 200–437 x 45-155 µm ( = 281 x 90 µm, n = 25), eight-spored, unitunicate, thin-walled, broadly clavate, with a long stipe ca. 50–100 µm long, swelling in water; ascus apex narrowly rounded, without an apical ring.

Ascospore:

Ascospores 84–126 x 20–34 µm ( = 109 x 27 µm, n = 50), irregularly arranged, one-celled, hyaline when young, ranging from golden to dark brown at maturity; fusiform, rough walled in a horizontal striated pattern; surrounded by a striated gelatinous sheath, germ pores not observed.

Sheath:

Striated gelatinous sheath, expanding in water to ca. 5–8 µm wide at the mid region, and ca. 10–20 µm long at the ascospore apices; sheath staining in aqueous nigrosin and India ink, absent in older ascospores.

Appendage:

Culture:

Colonies on potato dextrose agar (PDA, Difco) grown at 25°C, dark green in the center and hyaline towards the periphery. Ascomata formed at the center of colonies after 2-3 weeks on CMA and PDA, superficial to partially immersed in the agar.

Anamorph:

None observed

Other info

Type & Location:

USA, Ocala National Forest, Lake Kerr, on submerged, decorticated wood, 29°21'19''N, 81°48'45''E, UTM Zone 17, 17421130mE, 3247637mN, water temperature 21 C, pH 7, 3 March, 2005, Huzefa A. Raja, Andrew N. Miller, and J. L. Crane, F77-1. (ILL, slide made from a specimen on submerged, decorticated wood, F77-1.

Other Specimens:

Substratum:

Submerged, decorticated wood.

Habitat:

Lentic

Distribution:

USA: Florida

Pertinent Literature:

Raja, H.A. and Shearer, C.A. 2006. Arnium gigantosporum, a new ascomycete species from fresh water in Florida. Fungal Diversity 100: 1-2. Kruys, A., Hunhdorf, S.M., and Miller, A.N. Coprophilous contributions to the phylogeny of Lasiosphaeriaceae and allied taxa within Sordariales (Ascomycota, Fungi). Fungal Diversity

Comments:

Additional Pictures

Asci in various stages of development.
Young ascospore with sheath in India ink.
Young asci.
Ascus.
Mature ascus.
Germinating ascospore.
Ascospore wall roughening.
Ascospore wall roughening at 100X.
Striations in ascospore sheath. Stained with aqueous nigrosin.
Unstained ascospore sheaths.
Sticky sheaths twined together.

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