The genus Mytilinidion Duby, the type genus for the family Mytilinidiaceae, was established by Duby (1862) for M. aggregatum de Candolle ex Duby, with an etymology from Mytilus, a genus of mussels. Zogg (1962) however pointed out that none of the exsiccati contained identifiable material and proposed that M. mytilinellum (Fr.) Zogg be designated the neotype (Barr 1990). Saccardo (1883) considered the name Mytilinidion to be invalid and replaced it with Mytilidion Duby, a proposal supported by nearly all subsequent authors (e.g., Clements & Shear 1931; Ellis & Everhart 1895; Kirschstein 1924; Luttrell 1973; Massee 1895; Rehm 1896; von Arx & Müller 1975; Zogg 1962), until Barr (1975) correctly pointed out that the name Mytilinidion had historical precedence (Rogers 1953), and should replace the later name Mytilidion.  The genus is characterized by yellow- to reddish-brown ellipsoid, fussoid, obovoid to elongate traversely septate ascospores, borne in thin-walled globoid to conchiform pseudothecia, with lateral walls more or less convinent and extended vertically to a cristate apex. Lohman (1932) proposed two sub-genera within the genus: Eu-Mytilinidion for species with a spore ratio of length to width of 10:1 or less and subgenus Lophiopsis for a ratio of approximately 20:1, the latter to accommodate M. scolecosporum Lohman, M. parvulum Lohman and M. australe Lohman. These three scolecosporus species form a transitional series to connect Mytilinidion with the heretofore somewhat isolated genus Lophium. Lohman (1932) noted that spore germination in the subgenus Eu-Mytilinidion is polar, with the terminal cells germinating first; whereas in Lophiopsis spore germination is non-polar, with any cell capable of germinating first, as in the genus Lophium. Despite the presence of scolecospores in Lophiopsis, they do not exceed in the length half that of the ascus, thus presenting a more or less biseriate arrangement, as in Eu-Mytilinidion and unlike the single fasciculate arrangement in the linosporous genus Lophium. Zogg (1962) accepted Lohman’s (1932) two subgenera and recognized thirteen species occurring on members of the Pinaceae, Cupressaceae and Taxodiaceae, one of which has been subsequently transferred to Ostreichnion (Barr 1975), with another recently described from the resin of Araucaria in Brazil (Speer 1986).

Barr (1990): “Ascomata superficial, gregarious or scattered, occasionally two or three united, elongate or ellipsoid, conchate or shield shaped, small to medium sized; apex cristate, opening by longitudinal slit; surface black, smooth & shining or dull, often longitudinally striate; peridium narrow, carbonaceous, brittle, composed of small, thick-walled cells. Asci basal, cylindric. Trabeculae little branched, sparse in gel matrix. Ascospores yellowish, light brown, reddish brown, ellipsoid, fuscoid, obovoid or elongate, ends obtuse or acute, symmetric or asymmetric, three to multiseptate, constricted or not at septa; wall thing an smooth; guttulate or one globule in each cell; overlapping uniseriate or biseriate or in two fascicles in the ascus. Anamorphs coelomycetous or occasionally hyphomycetous where known. On periderm, wood, twigs, leaves of members of Pinaceae, Cupressaceae, Taxondiaceae. Type species: Mytilinidion aggregatum De Candolle ex Duby; Mytilinidion mytilinellum (Fries) Zogg. Zogg (1962) detailed the problems associated with the name M. aggregatum as the type species: none of the early exsiccati contains indentifiable material & Duby’s concept of the species in unclear to present-day mycologists. Fries’ description (1823) provides little assistance, but for the notation that to the naked eye the fungus appears as irregular black spots on bare wood, under the lens composed of compressed small ascomata with longitudinal slits. Zogg proposed that M. mytilinellum be designated as neotype, a known entity to typify the long-recognized genus. I suggest that both names may refer to the same species, based in part on the observation by Lohman (as M. laeviusculum, 1933) that to the eye the aggregated ascomata are seen only as a purple-black coloration of the substrate, in contrast to the individual ascomata of M. tortile. Zogg (1962) included Ostreion (= Ostreichnion) under Mytilinidion, but ascospores of O. americanum Duby (= O. sassafras (Schweinitz) Barr) differ considerably in sizes & septation. Ostreichnion is maintained as a separate genus in the family. Hypodermopsis Earle non Kuntze was based upon H. sequoiae. The original material of Earle’s species (Pacific Slope Fungi, dist. C.F. Baker n. 81, on Sequoia sepervirens, Summit of Coast Range, San Mateo Co., CA, 15 Nov 1901, NY) is a species that has ovoid, somewhat shield-shaped & cristate ascomata, with small three-septate ascospores, 13 – 15 x 4 – 4.5 um. The fungus appears to be identical with Mytilinidion californicum Ellis & Harkness, described from Sequoia (Sequoiadendron) gigantea. Zogg (1962) thought that M. californicum was the same as M. tortile & Lohman (1939) that it resembled M. decipiens. The scutate ascomata with thin basal peridium are more characteristic of M. acicola, & for the present these two species are separated by differences in sizes of ascospores & substrate. The illegitimate name Hypodermopsis Earle is a synonym of Mytilinidion. Nannfeldt (1932) placed it under Hysterium, whereas Zogg (1962) gave it as being of uncertain position. Cash (1939) utilized Earle’s genus for Hysterium smilacis (Schweinitz) Cash ( = Gloniopsis smilacis) which she consigned to the Hyperdermataceae, but which is now in the Pleosporales, Hysteriaceae. Murashkinskiya was described as a member of the Polystomellaceae (Petrack, 1929), with peridium of somewhat radiating rows of heavily pigmented cells that extend out as a marginal layer. Petrak observed the keel-like apex of ellipsoid ascomata; in this feature, as in all others, M. juniperina corresponds to Mytilinidion acicola & is treated as a synonym of that species. In addition to the species separated in the key & described below, several others are known from North America. Mytilinidion mytilinellum (Fries) Zogg was reported as M. laeviusculum (Karsten) Saccardo from Michigan (Lohman, 1933), & M. rhenanum Fuckel as M. karstenii from northeastern North America (Lohman, 1932). The ascospores in both species are narrowly fusoid, three-septate, (14-) 16 – 22 (-24) x (2.5-) 3 – 4 (-5) um for M. mytilinellum, & three- to five-septate, (24-) 30 – 42 (-50) x 3 – 5 um for M. rhenanum. Mytilinidion resinicola Lohman (1933) on Larix in Michigan forms similar colonies to those of M. tortile in culture; ascospores are larger, 24 – 26 x 8 – 9 um. Lohman (1932) also erected subgenus Lophiopsis for three new species: M. scolecosporum, M. parvulum, & M. australe, whose ascospores are elongate fusoid & several septate, longer than those of M. mytilinellum or M. rhenanum. These ascospores lie overlapping biseriate or in two fascicles in the ascus & are not arranged in a single fascicles as in species of Lophium.”

 Key to North American Species of Mytilinidion
(from Barr 1990)

1. Ascomata shield shaped, low & spreading at base

= go to 2.

1. Ascomata conchate, as high or higher than wide, tapered inward at base

= go to 3.

2. Ascospores 23 – 25 x 4 – 4.5 (-5)um, 3-septate; on Sequoia

= Mytilinidion californicum Ellis & Harkness

2. Ascospores 14 – 20 (-22) x (4.5-) 6 – 7.5um, 3 – 4 – 5 (6-) septate; on Juniperus, Thuja

= Mytilinidion acicola Winter

3. Ascospores obovoid or ellipsoid, ends obtuse, 11 – 15 x 4.5 – 6um, 3- (-4) septate

= Mytilinidion tortile (Schwein.: Fr.) Sacc.

3. Ascospores fusoid or narrowly obovoid, longer than 20um

= go to 4.

4. Ascospores fusoid, 25 – 35 x 8 – 12um, 3 – 4 – 5 sepate

= Mytilinidion thujarum (Cooke & Peck) Lohman

4. Ascospores narrowly obovoid, tapered downward, 32 – 42 x 7 – 8um, 7 – 8 septate

= Mytilinidion gemmigenum Fuckel

A. Subgenus Eu-Mytilinidion sensu Lohman: Relationship of spore length to width ratio = 10:1 or less.  

I. Conchiform fruitbody elongated mussel-shaped, measuring 1 mm or more long with a width of 0.2 – 0.5 mm or more.

(a) Ascospores slender spindle-forming to club-shaped.

1. Ascospores (two-) four- (six-) celled, measuring: (14) 16 – 22 (24) x (2.5) 3 – 4 (5) μm: 

= Mytilinidion mytilinellum (Fr. ) Zogg

 2. Ascospores four- to six- (eight-) celled, measuring: (24) 30 – 42 (50) x 3 – 5 μm:

= Mytilinidion rhenanum Fuckel

3. Ascospores (four-) eight- to ten- (twelve-) celled, measuring: (27) 32 – 38 (48) x (4) 5 – 6 (8) μm:

= Mytilinidion gemmigenum Fuckel

(b) Ascospores oblong to elliptic.

1. Ascospores four- (six-) celled:

Ascospores measuring: (11) 14 – 17 (21) x 5 – 7 (8) μm:

= Mytilinidion tortile (Schw.) Ell. et Ev. 

Ascospores measuring: 24 – 26 x 8 – 9 μm: 

= Mytilinidion resinicola Lohman 

Ascospores measuring: (26) 30 – 34 (40) x (10) 12 – 13 (15) μm:

= Mytilinidion thujarum (C. & P.) Lohman 

 Ascospores measuring: 27 – 33 x 7 – 8.5 μm:

= Mytilinidion oblongisporum Teng  

2. Ascospores twelve- to twenty-celled, measuring: 80 – 100 (120) x 23 – 27 (35) μm:

= Mytilinidion sassafras (Schw.) Zogg                                   

II. Conchiform fruitbody oval to roundish 0.5mm long by 0.3mmm thick.

(a) Fruitbody mussel-shaped; ascospores oblong to ellipsoid, four-celled, measuring (11) 13 – 15 (16) x 3 – 4 (6) μm:

= Mytilinidion decipiens (Karst.) Sacc. 

(b) Fruitbody shield-forming; ascospores oblong to ellipsoid, four-celled (3- septate), measuring (13) 15 – 20 (28) x (5) 6 – 8 (10) μm:

= Mytilinidion acicola Winter  

(c) Fruitbody shield-forming; ascospores 23 – 25 x 4 – 4.5 (-5)um, 3-septate; on Sequoia:

= Mytilinidion californicum Ellis & Harkness  

 

B. Subgenus Lophiopsis sensu Lohman (1932): Relationship of spore length to width ration = +/- 20:1 – i.e., long scolecospores or filiform spores. 

I. Fruitbody mussel-forming or clam-shaped.

 (a) Ascospores six- to eight-celled measuring 40 – 50 x 2 – 2.5 μm:

= Mytilinidion scolecosporum Lohman

 (b) Ascospores eight- to ten- (twelve-) celled, (48) 54 – 62 (65) x 2.5 – 3 μm:

= Mytilinidion parvulum Lohman

II. Fruitbody mussel-forming or clam-shaped, but ends distended into a very prominant keel like cistate apex. 

= Mytilinidion australe Lohman

Detailed Dichotomous Key to species of Mytilinidion Duby
(from Zogg 1962)

A. Subgenus Eu-Mytilinidion sensu Lohman: Relationship of spore length to width ratio = 10:1 or less.

Lohman (1932): “Spores clear yellow-brown to fuscous, with a ratio of length to breadth of approximately 10:1 or less. In this subgenus (which is the genus Mytilinidion of most authors) there is correlated with the ratio of measurements, the phenomena of polarity in germination, i.e., the terminal cells of the spore germinate first, & often only these cells germinate.”

I. Conchiform fruitbody elongated mussel-shaped, measuring 1 mm or more long with a width of 0.2 – 0.5 mm or more.

(a) Ascospores slender spindle-forming to club-shaped. 

1. Ascospores (two-) four- (six-) celled, measuring: (14) 16 – 22 (24) x (2.5) 3 – 4 (5) μm: 

= Mytilinidion mytilinellum (Fr. ) Zogg  

 

Zogg, 1962. Rather rare. European Alps. Collected from old, weathered wood, bark & cones of Pinus, Larix and Picea.

Lophium mytilinellum Fries, 1823

Mytilidion decipiens (Karst.) Sacc, var. conorum Sacc., 1878

Lophium laeviusculum Karst., 1871

Mytilidion laeviusculum (Karst.) Sacc., 1883

2. Ascospores four- to six- (eight-) celled, measuring: (24) 30 – 42 (50) x 3 – 5 μm:

= Mytilinidion rhenanum Fuckel

 

Symb. Myc., I. Nachtr., 1871, 10 (298), 11 (299). Rather rare. Europe (Germany). Collected from old often weathered bark, wood & wood knots of Pinus.

 

Mytilidion Karstenii Sacc., 1883

Lophium mytilinum (Pers.) Fr. sensu Karst., 1873

Mytilidion rhenanum var. intricatissimum Karst., 1885

3. Ascospores (four-) eight- to ten- (twelve-) celled, measuring: (27) 32 – 38 (48) x (4) 5 – 6 (8) μm: 

= Mytilinidion gemmigenum Fuckel

Symb. Myc., I. Nachtr., 1871, 11 (299) [Zogg, 1962]. [Barr (1990): Jahrb. Nassauischen Vereins Naturk. 25 – 26: 299. 1871]. Rather rare. Alpine Europe (Mitteleuropa). old bark, wood & cones of Pinus & Larix.

 

Lophium fusisporum Cooke, 1876

Mytilidion fusisporum (Cooke) Sacc., 1883

Mytilidion insulare Sacc. (in Barbey, 1884)

 

Barr (1990): “Ascomata conchate, 400 – 1000um long, 300 – 400 um wide & high; peridium thin, blackish brown. Asci 100 – 150 x 10 – 15 um. Ascospores (27-) 36 – 42 (-48) x (4-) 5 – 7 (-8) um, brown, 1 – 8 – 9 – (11-) septate. Distribution on old wood & bark of Pinaceae north temperate zone.  The only North American collection of this species examined accords well with descriptions from Europe, where it is rare on wood of Larix & Pinus species (Zogg, 1962).”

 

(b) Ascospores oblong to elliptic.

1. Ascospores four- (six-) celled:

Ascospores measuring: (11) 14 – 17 (21) x 5 – 7 (8) μm:

= Mytilinidion tortile (Schw.) Ell. et Ev.

 

N. Amer. Pyrenomycete, 1892, 688-689. Rather rare. European alpine belt & from North America. Collected from wood & bark of Pinus, Larix, Picea, Juniperus. 

 

Hysterium tortile Schweinitz, 1822

Mytilidion juniperi Ellis et Everhart, 1888

 

Note: Barr (1990), differs from Zogg (1962), & provides the following specific epithet for this taxon: Mytilinidion tortile (Schweinitz: Fries) Saccardo, Syll. Fung. 2: 763. 1883.

 

Ellis & Everhardt (1892): “Hysterothecia gregarious, superficial, lying in various directions on the matrix, membraneous to carbonaceous, black, brittle, shaped like clam shells with the sharp edges pointing up, 1 – 1.5mm; lips closed, acute, sides of fruitbody more or less distinctly longitudinally striate. Asci cylindrical , 75 – 80 x 6 μm with a stipitate base 12 – 15 μm long. Paraphyses obscured at maturity. Ascospores uniseriate, oblong, three- (rarely four-) septate, pale brown, 12 – 15 x 4 – 5 μm, ends obtuse, only slightly or not at all constricted at the septa. On bark of Juniperus virginiana from Carolinas & Pennsylvania (Schw.), also around Newfield, NJ (Ellis).”

 

Lohman (1933) “On bark of living Juniperus virginiana (Michigan). Hysterothecia loosely gregarious & inordinately arranged, superficial, black, occasionally longitudinally striate, (0.5) 0.7 – 1.2 (1.5) mm in length, 0.2 – 0.3 mm in breadth, the height equaling or slightly exceeding the width, sub-conchiform & rounded above or elongate with pointed ends & then usually acutely keeled; walls prosenchymatous, thin, carbonaceous, & fragile; asci slender-clavate, (65) 75 – 85 x 6 – 8 μm, the inner ascus becoming 115 – 130 μm in length on expansion; paraphyses abundant, 2 μm in diameter, hyaline, septate, irregularly branched above, forming a yellowish epithecium; spores obliquely uniseriate, clear yellow-brown to slate-brown, 3-septate, 13 – 16 (18) x 4 – 5 μm or very rarely 20 μm long & 4-septate, mostly oblong-fusiform & slightly curved, with obtuse ends & slight constrictions.”

 

Barr (1990): “Ascomata conchate, 500 – 1000(-1500) um long, 200 – 340 (-500) um diam.; surface longitudinally striate; peridium thin, brittle, blackish brown. Asci 75 – 100 x 6 – 8 um. Ascospores 11 – 16 (-20) x 4 – 6 um, brown, ellipsoid oblong, (2-) 3 – (4 – 5) septate. Lohman (1933) obtained small pycnidia in culture, conidiogenous cells 4 – 6 x 3 um, conidia hyaline, subglobose, 2 um diam. He also reported, as M. decipiens (Karsten) Saccardo, a culture in which the pycnidia were Pyrenochaeta-like, setose, with conidia 1.5 um or 2 x 1.5 um. The description of the teleomorph from Picea agrees better with M. tortile than with M. decipiens. The two names may refer to only one species, although Zogg (1962) separated M. decipiens with shorter & smaller ascomata. On wood & bark of various gymnosperms, north temperate zone. Pseudotsuga menziesii (ID) & Juniperus virginiana (NJ).”

 

 

Ascospores measuring: 24 – 26 x 8 – 9 μm:

 

= Mytilinidion resinicola Lohman

 

Pap. Mich. Acad. Sci. Arts & Letters, 1933, 17, 256-258. Rare. North America. Collected from old bark of Larix.

 

Lohman (1933): “Hysterothecia loosely gregarious & lying  in various directions, superficial, straight, black, rugose-punctate to faintly longitudinally striate, 0.75 – 1.25 x 0.25 – 0.3 mm, sub-conchiform with a sharp ridge or depressed hysteriform, occasionally 3-radiate, accompanied by a compact, black carbonaceous crust of close-septate, torulose, interwoven hyphae; walls prosenchymatous, thin, carbonaceous, & fragile; asci double-walled, 100 – 110 x 15 μm; paraphyses hyaline, septate, much branched & interwoven above; spores 24 – 26 x 8 – 9 μm, elliptic-oblong with rounded ends, 3-septate & deeply constricted at the septa, yellow-brown to dark fuscous & nearly opaque, & biseriate, becoming obliquely uniseriate in the extended inner ascus. On resinous exudation & the surrounding bark, confined to knots on fallen & erect dead trunks of Larix laricina (Du Roi) Koch (Michigan). The asci & spores are similar to those of Hysterium angustatum Alb. & Schw., but the hysterothecia have the form & texture of Mytilinidion. In its diagnostic features the fungus approaches M. aggregatum (DC.) Duby & M. rhenanum Fuckel. It differs form the former in that the spores are larger with all of the cells colored, & from the latter in that the spores are broader & constricted.”

 

 

Ascospores measuring: (26) 30 – 34 (40) x (10) 12 – 13 (15) μm:

 

= Mytilinidion thujarum (C. & P.) Lohman

 

Pap. Mich. Acad. Sci. Arts & Letters, 1933, 17, 258-259. Collected on Juniperus virginianum & Thuja occidentalis bark [Bisby (1932) & Lohman (1933a)].

 

Hysterium thujarum Cooke et Peck (in Cooke, 1877)

 

[Barr, 1990: in Cooke, Bull. Buffalo Soc. Nat. Sci. 3: 33. 1875. Type: Thuja occidentalis, New Baltimore, Green Co., NY Jul 1871, E.C. Howe NYS! (isotype)].

 

Lohman (1933): “On inner bark, old stumps of Thuja occidentalis L. Hysterothecia 0.4 – 0.8 (1) x 0.25 – 0.4 mm; asci 140 – 170 x 15 – 18 μm; spores 34 – 40 x 10 – 12 μm, rich brown, slightly curved, pointed below, 4- to 5 (6) septate, constricted at the septa, with the third cell from the upper end swollen. Young hysterothecia are black & shining, vertically compressed, with pointed ends & a sharp ridge, & as they develop the crest becomes obtusely rounded & more or less distinctly longitudinally striate. Of greater importance in the proper classification of this species is the fact that even at maturity the walls of the hysterothecium are thin & fragile, with the structure of Mytilinidion.”

 

Barr (1990): “Ascomata conchate, up to 1mm long, 385 – 440um dia., surface faintly longirudinally striate; peridium up to 50um wide, blackish brown. Asci 150 – 160 x 15 – 20 um. Ascospores 25 – 35 x 8 – 12um fusoid, brown, 3- (4 – 5) septate. Distribution: On wold wood of Thuja occidentalis, northeastern North America. Note: This species is also known from MI & WI (Lohman, 1933). The ultures obtained by Lohman remained sterile but he found empty associated pycnidia on the substrate.”

Mytilinidion thujarum (C. & P.) Lohman

Ascospores measuring: 27 – 33 x 7 – 8.5 μm:

= Mytilinidion oblongisporum Teng

Sinensia, 1936, 7, 491. Collected in China on unidentified wood.

 

2. Ascospores twelve- to twenty-celled, measuring: 80 – 100 (120) x 23 – 27 (35) μm: 

= Mytilinidion sassafras (Schw.) Zogg    

                               

Rare. North America & China. Collected from trunk & bark of Quercus, Sassafras & Liquidambar.

 

Lophium sassafras Schweinitz. 1834

Ostreion americanum Duby, 1862

 

Note: Barr (1975, 1990) transferred Mytilinidion sassafras (Schw.) Zogg to Ostreichnion sassafras (Schw.) Barr

 

 

II. Conchiform fruitbody oval to roundish 0.5mm long by 0.3mmm thick.

(a) Fruitbody mussel-shaped; ascospores oblong to ellipsoid, four-celled, measuring (11) 13 – 15 (16) x 3 – 4 (6) μm: 

= Mytilinidion decipiens (Karst.) Sacc.

 

Michelia I, 1877, 55. Quite rare. Alpine belt in Europe. From the living bark of Larix & Juniper.

 

Lophium decipiens Karst., 1871

 

Lohman (1933): “On inner bark, old stumps of Picea canadensis (Michigan). Hysterothecia 0.3 – 0.5 (0.6) x 0.1 – 0.2 mm, about as high as broad, with the swollen central portion faintly striated & the acuminate, smooth ends free from the substratum; asci 75 – 90 x 8 – 10 μm; paraphyses hyaline, much branched, & interwoven above; spores 15 – 21 x 5 – 6 μm, clear yellow-brown sub-biseriate, 3-septate, unconstricted, slightly curved, oblong-elliptic with obtuse ends, the lower cell in most specimens narrower than the upper.”

(b) Fruitbody shield-forming; ascospores oblong to ellipsoid, four-celled (3-septate), measuring (13) 15 – 20 (28) x (5) 6 – 8 (10) μm:

= Mytilinidion acicola Winter

 

Hedwigia, 1880, 19, 176. Rather common. Alpine Switzerland. From the living branches and twigs of Juniperus.

 

Barr (1990) lists the following synonyms:

 

Lophiostoma thujae Ellis & Everhart

Navicella thujae (Ellis & Everhart) Kuntze

Murashkinskiya juniperina Petrak

 

Barr (1990): “Ascomata elongate, scutate, 200 – 770 um long, 150 – 385 um wide, up to 550 um at base, 165 – 275 um high; peridium 15 – 30 um side at sides, thin at base. Asci (57-) 95 – 120 x 7.5 – 11 um. Ascospores 14 – 22 (-28) x (4.5-) 6 – 8 9-10) um, clear brown, 3 – 5 (-6) septate. Distribution on twigs & leaves of Cupressaceae, alpine & arctic especially in north temperate zone. Germany, Canada, Maine, Vermont. On Juniperus horizontalis, Thuja occidentalis & Juniperus communis. The collections with mostly five-septate ascospores from Vermont & northern Quebec do not differ in other characteristics from M. acicola, nor do those on Thuja rather than Juniperus. The type collection of Lophiostoma thujae has not been located, but from the description it is identical with M. acicola. Zogg (1962) reported this species as common in alpine areas of Europe on several species of Juniperus.”

 (c) Fruitbody shield-forming; ascospores 23 – 25 x 4 – 4.5 (-5)um, 3-septate; on Sequoia:  

= Mytilinidion californicum Ellis & Harkness 

 

Bull. Torrey Bot. Club 8: 51. 1881. Type: on Sequoia gigantea, California, Harkness.

 

Hypodermopsis sequoiae Earle, Bull. New York Bot. Gard. 2: 345. 1902. Type: Sequoia sempervirens, Summit of coast range, San Matao Co., CA 15  Nov 1901, C.F. Baker = Pacific Slope Fungi 81 NY! (isotype).

 

Barr (1990): “Ascomata scutate, elongate, up to 500um long, 130 – 156 um wide, 117 – 130um high, base widened; surface faintly longitudinally striate near margin; peridium ca. 15um wide at sides, pallid & narrow at base. Asci 50 – 60 x 8 – 10um. Ascospores 13 – 15 x 4 – 4.5 (-6)um, yellowish brown, 3 – 5 – (6-) septate. Distribution: on leaves & twigs of Sequoia & Sequoiadendron, western North America. This species is closely related to Mytilinidion acicola. Both have elongate, shield-shaped ascomata whose bases are wide on the substrate. The ascospores in M. californicum are narrower than those in M. acicola, ad the habitats also differ: Sequoia & Sequoiadendron in the Taxodiaceae versus Juniperus or Thuja in the Cupressaceae. Mytilidion sequoiae Ellis & Harkness is an unpublished name that should be referred to M. californicum.”

B. Subgenus Lophiopsis sensu Lohman (1932): Relationship of spore length to width ration = +/- 20:1 – i.e., long scolecospores or filiform spores.

Lohman (1932): “Spores yellowish to yellow-brown, with a ratio of length to breadth of approximately 20 : 1. In this subgenus there is correlated with the ratio f measurements of the ascospore a condition of non-polarity in germination, i.e., any cell of the spore may be the first to germinate (as in Lophium mytilinum (Pers.) Fries.)". The following three species are accommodated in the subgenus Lophiopsis:"

[Wehmeyer (1975): "Mytilinidion scolecosporum has produced Septonema toruloideum (Lohman 1933). Certain species of Mytilinidion (e.g., M. scolecosporum with long-cylindric, septate, biseriate ascospores which have a ration of length to width of twenty : one or about half the length of the ascus, are intermediate between the genus Mytilinidion and the genus Lophium. These have been placed by Lohman (1932) in the subgenus Lophiopsis."]

 I. Fruitbody mussel-forming or clam-shaped. 

(a) Ascospores six- to eight-celled measuring 40 – 50 x 2 – 2.5 μm: 

= Mytilinidion scolecosporum Lohman 

 

Lohman (1932): “Hysterothecia conchiform but not acutely keeled, densely gregarious, 0.4 – 0.8 (1) x 0.2 – 0.3 mm (0.2 – 0.4 mm in height), dull black & longitudinally striate, occasionally three-radiate & erect, or in pairs & horizontally disposed, superficial from the beginning on an effused black crust made more prominent in places by the minute, punctiform centers of conidial sporulation; walls prosenchymatous, thin, carbonaceous & fragile; asci subcylindric, 100 – 130 x 4 – 4.5 μm; paraphyses delicate, hyaline, septate, sparingly branched & interwoven above; spores 40 – 50 x 2 – 2.5 μm, subvermiform, occasionally bent or subsigmoid, yellowish to clear brown, subspirally biseriate, 5- to 7-spetate & slightly constricted at the septa; conidia elliptic-oblong, tapered apically, deep fuscous throughout or with one or two of the apical cells paler, 3- to 5-septate, 14 – 18 (24) x 4.5 – 5 (6) μm, deeply constricted, arranged in erect or variously decumbent, simple or sparingly branched, easily broken chains 75 to 200 μm in length; pycnidia unknown. On wood of much weathered stump of Pinus strobes L. (Wisconsin). This species, distinct in its subvermiform spores, shows its relationship to the species of the preceding section through M. Karstenii Sacc., M. rhenanum Fuckel & M. thujae Feltig.”

 

 

(b) Ascospores eight- to ten- (twelve-) celled, (48) 54 – 62 (65) x 2.5 – 3 μm:

= Mytilinidion parvulum Lohman

 

Lohman (1932): “Hysterothecia conchiform & acutely keeled, superficial, black & shining, 0.3 – 0.5 x 0.15 – 0.18 mm (0.2 – 0.3 mm in height), arranged in loose but widespread aggregations which blacken the substratum; walls prosenchymatous, thin, carbonaceous & fragile; asci subcylindric, 8-spored, 120 – 130 (135) x 6 – 7.5 μm; paraphyses sparse, delicate, hyaline, septate, sparingly branched & interwoven above; spores (48) 54 – 62 x 2.7 – 3 μm, slender clavate with the upper end broadly obruse & the lower pointed, usually slightly bent in the lower half, yellowish brown, subspirally biseriate, 7- t0 9-septate (or becoming 11-septate by less distinct walls through several of the cells) & unconstricted. On bark & wood of old stump (Pinus), (Massachusetts). Although fructifications small, it has longer spores than does either M. scolecosporum or M. Karstenii. hence, it approaches Lophium mytilinum more closely than does either of the two species just mentioned.”

II. Fruitbody mussel-forming or clam-shaped, but with a splayed-out fan-shaped crested apice, ascospores (10) 11- to 14-sepate & unconstricted, measuring (54) 58 – 70 (75) x 3 – 4 μm.

= Mytilinidion australe Lohman 

 

Lohman (1932): "Hysterothecia vertically appressed with fan-shaped crests, densely aggregated in small scattered clusters, 0..4 – 0.6 (0.8) x 0.15 – 0.2 mm (0.3 – 0.4 mm in height), vertically & longitudinally striate, black & shining; walls prosenchymatous, thin, carbonaceous & fragile; asci subcylindric, 8-spored, 125 – 150 x 8 – 9 μm; paraphyses sparse, delicate, hyaline, septate, branched & interwoven above; spores (54) 58 – 70 (75) x 3 – 4 μm, elongate, tapered equally toward each end, slightly curved to sublunate, yellowish, subspirally biseriate, (10) 11- to 14-sepate & unconstricted. On much decayed wood of Pinus, (Louisiana). Since there is no black fungous layer  present, the rather scattered, slender fructifications on the weathered wood are scarcely noticeable to the unaided eye. The long, slightly curved sores with may septa could not be confused with those of any known species of the genus.”