The genus Mytilinidion Duby 
Mem. Soc. Phys. Hist. Nat. Geneve 16: 34 (1862)

by Eric W.A. Boehm

A-B. Mytilinidion tortile (EB 0377 [BPI 879798], France). C-D. Mytilinidion mytilinellum (EB 0386 [BPI 879796], France).
E-I. Mytilinidion australe (ANM 1524 [ILLS], USA; not incl.). J-K. Lophium mytilinum (CBS 123344 [BPI 878736], USA).
For genus Lophium see following page. Photo credits Alain Gardiennet, Figs. A-D. Scale bar (habitat) = 500 μm; Scale bar (spores and asci) = 10 μm.
Fig. 11 from Boehm et al. 2009b.

Mytilidion Saccardo 1875
Hypodermopsis Earle non Kuntze 1898
Murashkinskiya Petrak 1928

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, p. 760) 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, fusoid, obovoid to elongate, transversely septate ascospores, borne in thin-walled globoid to conchate pseudothecia, with lateral walls more or less connivent and extended vertically to a cristate apex.

Lohman (1932b) proposed two sub-genera within the genus Mytilinidion: subgenus Eu-Mytilinidion for species with a spore ratio of length to width of 10:1 or less to include species with typical phragmospores, and subgenus Lophiopsis to include species with scolecospores, typified by a ratio of approximately 20:1, the latter to accommodate M. scolecosporum Lohman, M. parvulum Lohman and M. australe Lohman. These three scolecosporous species form a transitional series to connect the genus Mytilinidion sens. lat. with the heretofore somewhat isolated genus Lophium. Lohman (1932b) 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 half the length of the ascus, thus presenting a biseriate arrangement, as in Eu-Mytilinidion, and unlike the single fasciculate arrangement in the filiform genus Lophium. Zogg (1962) accepted Lohman’s (1932b) two subgenera and recognised 13 species occurring on members of the Pinaceae, Cupressaceae, 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), and, in Boehm et al. (2009), we have recognized M. andinense (Messuti & Lorenzo) Boehm, Schoch & Spatafora, thus bringing the total number of species in the genus to 15.

Several morphological lines can be identified in the genus Mytilinidion sens. lat. Two series can be discerned based on fruitbody shape, namely scutate ascomata, seated on a spreading base fused to the substrate (M. californicum Ellis & Harkness & M. acicola Winter), and the remainder of the species that typically posses strongly laterally compressed, conchate fruitbodies, with lateral walls more or less connivent, and extended vertically to a prominent longitudinal keel or cristate apex. Ascospore morphology in the genus Mytilinidion sens. lat. can also be used to discern four morphological transition series within the genus, listed here by increasing ascospore length: (1) Short squat phragmosporesM. californicum Ellis & Harkness, M. acicola Winter, M. resinae Speer, M. decipiens (Karst.) Sacc., M. tortile (Schw. : Fr.) Sacc., & M. resinicola M.L. Lohman; (2) Fusoid or spindle-shaped sporesM. thujarum (Cooke & Peck) M.L. Lohman, M. oblongisporum Teng, & M. andinense (Messuti & Lorenzo) Boehm, Schoch & Spatafora; (3) Elongate phragmospores, with a spore ratio of length to width of 10:1 or less: M. mytilinellum (Fr.) Zogg, M. rhenanum Fuckel, & M. gemmigenum Fuckel; and (4) Highly elongated phragmospores (scolecospores), with a ratio of approximately 20:1 (subgenus Lophiopsis): M. scolecosporum M.L. Lohman, M. parvulum M.L. Lohman, & M. australe M.L. Lohman.

Recent molecular evidence, based on a taxon sampling of seven of the 15 currently species, including members from both the subgenus Eu-Mytilinidion and Lophiopsis, indicate that the genus Mytilinidion sens. lat., along with the genus Lophium, form a highly supported clade, thus defining a monophyletic Mytilinidiaceae within the Pleosporomycetidae, for which we proposed the Mytilinidiales ord. nov. (Boehm et al. 2009). Phylogenetic data also provided little support for the two sub-genera proposed by Lohman (1932b) for the genus Mytilinidion sens. lat. Thus, species belonging to the subgenus Lophiopsis, namely M. scolecosporum and M. australe, did not segregate from species belonging to the subgenus Eu-Mytilinidion. Instead each found affinity with non-scolecosporous species in Eu-Mytilinidion. For instance, M. scolecosporum, with five- to seven-septate sub-vermiform ascospores, segregates along with M. rhenanum, a species characterized by four- to six-septate elongate phragmospores, a relationship already predicted by Lohman (1932b). But, M. rhenanum also shares the same clade as M. resinicola, a species characterized by short, squat, deeply constricted, phragmospores, the Mytilinidion counterpart of H. angustatum (see Lohman 1933b). These three taxa form a clade closely associated with one isolate of the filiform genus Lophium. The second clade within the family includes the short-spored M. tortile and elongate M. mytilinellum, the type. Surprisingly, M. australe, with scolecospores, previously classified as a member of the subgenus Lophiopsis, and previously allied with the only other scolecosporous taxon surveyed in this study, namely M. scolecosporum, clusters instead with the Eu-Mytilinidion representatives, M. tortile and M. mytilinellum (Zogg 1962). This finding indicates that the evolution of scolecospores within the genus Mytilinidion sens. lat. has evolved at least twice, and argues against the recognition of the subgenus Lophiopsis proposed by Lohman (1932b). Despite the lack of support from molecular data for the subgenus Lophiopsis, it is included in the key below to facilitate species identification.

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 (Sequoiadendrongigantea. 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 PleosporalesHysteriaceaeMurashkinskiya 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) μm for M. mytilinellum, & three- to five-septate, (24-) 30 – 42 (-50) x 3 – 5 μm for M. rhenanumMytilinidion 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 μm. 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 species of Mytilinidion Duby

  1. Spore length to width ratio = 10 : 1 or less (phragmospores): Subgenus Eu-MytilinidionsensuLohman (1932b) → 2
  2. Spore length to width ratio = approx. 20 : 1 (scolecospores): Subgenus Lophiopsissensu Lohman (1932b) → 13


  1. Ascomata not conchate, but erect, low and spreading at the base (scutate), seated on a shield-like process fused to the substrate, apical portion slightly connivent; ascospores 3-5(-6)-septate → 3
  2. Ascomata conchate, standing on edge, usually with a clearly defined longitudinal cristate apex → 4


  1. Ascospores 23-25 x 4-4.5(-5) μm, 3-septate; California on Sequoia → Mytilinidion californicum Ellis & Harkness
  2. Ascospores 14-22(-28) x (4.5-)6-8(-10) μm, 3-4-5-(-6) septate; on JuniperusThuja, Europe and North America →  Mytilinidion acicolaWinter


  1. Ascospores elongate phragmospores, usually not constricted at the septa → 5
  2. Ascospores shorter, squat, or longer, but not narrowly elongated, usually constricted at median septum → 7


  1. Ascospores (2-)3(-5)-septate, measuring (14-)16-22(-24) x (2.5-)3-4(-5) μm; cosmopolitan → Mytilinidion mytilinellum(Fr.) Zogg
  2. Ascospores longer, with more septa → 6


  1. Ascospores 3-5(-7)-septate, measuring (24-)30-42(-50) x 3-5 μm; Europe → Mytilinidion rhenanum Fuckel
  2. Ascospores slightly curved, asymmetric, (3-)7-9(-11)-septate, measuring (27-)32-38(-48) x (4-)5-6(-8) μm;   cosmopolitan → Mytilinidion gemmigenum Fuckel


  1. Ascospores (2-)3-septate, small, 10-13 x 4-6 μm; resinicolous on Araucaria, Brazil → Mytilinidion resinaeSpeer
  2. Ascospores 3(-5)-septate, longer → 8


  1. Ascospores 3-septate, slightly curved, oblong-elliptic, with obtuse ends, unconstricted, measuring (11-)13-15(-21) x 3-4(-6) μm; on LarixJuniperus, Europe → Mytilinidion decipiens (Karst.) Sacc.
  2. Ascospores longer, or similar in length but then slightly wider → 9


  1. Ascospores 3-septate, slightly curved, but oblong, fusiform, with slight constrictions, measuring (11-)14-17(-21) x 5-7(-8) μm; cosmopolitan → Mytilinidion tortile (Schw. : Fr.) Sacc.
  2. Ascospores longer → 10


  1. Ascospores 3-septate, elliptic-oblong, deeply constricted at the septa, measuring 24-26 x 8-9 μm; North America → Mytilinidion resinicola M.L. Lohman
  2. Ascospores longer, fusoid → 11


  1. Ascospores 3-septate, constricted at the median septum, measuring 27-33 x 7-8.5 μm; China and northwestern North America → Mytilinidion oblongisporum Teng
  2. Ascospores longer → 12


  1. Ascospores 3-(4-5)-septate, measuring (26-)30-34(-40) x (10-)12-13(-15) μm; on Thuja, cosmopolitan → Mytilinidion thujarum(Cooke & Peck) M.L. Lohman
  2. Ascospores wider, 3-7(-9)-septate, with swollen middle cells, 32-44 x 10-15 μm; on Austrocedrus chilensis, Argentina→ Mytilinidion andinensis(Lorenzo & Messuti) E.W.A. Boehm, C.L. Schoch & J.W. Spatafora


  1. Ascospores 5-7-septate, measuring 40-50 x 2-2.5 μm, slightly constricted at central septa; North America and Europe → Mytilinidion scolecosporumM.L. Lohman
  2. Ascospores longer, with more septa, less constricted → 14


  1. Ascospores 7-9(-11)-septate, measuring (48-)54-62(-65) x 2.7-3 μm; North America → Mytilinidion parvulumM.L. Lohman
  2. Ascospores (10-)11-14-septate, measuring (54-)58-70(-75) x 3-4 μm; North America → Mytilinidion australeM.L. Lohman


Mytilinidion mytilinellum (Fr.) Zogg

Zogg H, 1962. Beiträge zur Kryptogamen Schweiz, Band 11(3): 106.

Lophium mytilinellum Fries, 1823
Mytilidion decipiens (Karst.) Sacc, var. conorum Sacc., 1878
Lophium laeviusculum Karst., 1871
Mytilidion laeviusculum (Karst.) Sacc., 1883

Rather rare. European Alps. Collected from old, weathered wood, bark & cones of Pinus, Larix and Picea. The type species for the genus. Recent collections from North Central France, thanks to Alain Gardiennet.

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Mytilinidion mytilinellum (Fr.) Zogg. From left: Zogg (1962) pg. 105, 107. Photo credits © Alain Gardiennet. AG09092#, 6/4/2009, France, on Picea abies.
Many thanks to my friend & collaborator Alain Gardiennet for the use of his magnificent photos.

Mytilinidion rhenanum Fuckel

Fuckel, Symb. Myc., I. Nachtr., 1871, 10: 298, 11: 299

Mytilidion Karstenii Sacc., 1883
Lophium mytilinum (Pers.) Fr. sensu Karst., 1873
Mytilidion rhenanum var. intricatissimum Karst., 1885

Rather rare. Europe (Germany). Collected from old often weathered bark, wood & wood knots of Pinus.




Mytilinidion rhenanum Fuckel. Zogg (1962) pg. 105, 110.


Mytilinidion gemmigenum Fuckel

Symb. myc., I. Nachtr., 1871, 11 (299)*

Lophium fusisporum Cooke, 1876
Mytilidion fusisporum (Cooke) Sacc., 1883
Mytilidion insulare Sacc. (in Barbey, 1884)

Rather rare. Alpine Europe (Mitteleuropa), but also in the USA; on old bark, wood & cones of Pinus & Larix (Pinaceae).

*Note: Barr (1990) gives the source as Jahrb. Nassauischen Vereins Naturk. 25 – 26: 299. 1871.

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).”










Mytilidion gemmigenum Fuckel. Above from Zogg (1962), pg. 105, 112.
Photo credits © Alain Gardiennet. Collected in France, from Larix decidua, AG08JT7# on 11/7/8.


Mytilinidion resinae Speer

Speer, Mull. Soc. Myc. Fr. 1, 102: 98. 1986.

Speer (1986) (translated): “Collected from the extruded resin droplets of Araucaria angustifolia O. Kuntze, from the south of Brazil. Ascocarps conchiform, superficial and sessile, on resin substrata, lightly striated on the surface, measuring 200-500 μm in length, 100-150 μm in width, and 133-150 μm in height. Dehiscence effectuated by a longitudinal crest-like opening. Peridium 20-35 μm thick of pigmented isodimateric cells. Asci octospored, cylindric with rounded summit, 50-60 μm in length, diameter of 8-10 μm, accompanied by simple paraphyses. Paraphyses measuring 2-2.5 μm in diamter, are numerous and entangled above the asci, often irregular along their length. Ascospores three-septate, brown, ellipsoid to obovoid, measuring  10-13 x 4-6 μm. Ascocarps sometimes physically joined with the anamorphic state by identical dark hyphae as those composing the telomorph. Anamorph pycnidial belonging to the Sphaeropsidales type, named here as Camaroglobulus resinae Speer. Pycnidia are grouped on the surface, sometimes slightly immersed in the resin, globular, measuring 80-120 μm, with fertile, spore bearing regions distributed through in irregular lacunae. Conidiophores hyaline, measuring 7-10 μm x 1-3 μm in diameter, producing the blastospore development type. Conida are yellow-brown, irregular in outline, diameter of 2-4 μm. In short, a beautiful fungus”.


Mytilinidion tortile (Schw. : Fr.) Sacc.

Saccardo, Syll. Fung. 2: 763. 1883*

Hysterium tortile Schweinitz, 1822
Mytilidion juniperi Ellis et Everhart, 1888

Rather rare. European alpine belt & from North America. Collected from wood & bark of Pinus, Larix, Picea, Juniperus.

*Note: Barr (1990) authority differs from Zogg (1962) who provides: Mytilidion tortile (Schweinitz) Ellis et Everhardt non Sacc. N. Amer. Pyrenomycetes 1892, 688-689.

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) μm 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 or 2 x 1.5 μm. 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).”





Mytilinidion tortile (Schw. : Fr.) Sacc. Photo credits ©Alain Gardiennet. Left to right: AG09002#, France, collected from Pinus sylvestris, 8/1/2009;

AG09028# (spores), on Pinus sylvestris, 20/2/2009; AG09083#, France, from Juniperus communis, 23/3/2009. Note: tortuous ascomata.


Mytilinidion tortile(Schw. : Fr.) Sacc. Zogg (1962), pgs. 105, 114.

Mytilinidion resinicola M.L. Lohman

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.”






Mytilinidion resinicola M.L. Lohman. From Lohman (1933), pg. 258.

Mytilinidion thujarum (Cooke & Peck) M.L. Lohman

Lohman, Pap. Michigan Acad. Sci. Arts & Letters, 17: 258. 1933.

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)]. Collected on Juniperus virginianum & Thuja occidentalis bark [Bisby (1932) & Lohman (1933a)].

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 50 μm wide, blackish brown. Asci 150 – 160 x 15 – 20 μm. Ascospores 25 – 35 x 8 – 12 μm fusoid, brown, 3- (4 – 5) septate. Distribution: On old wood of Thuja occidentalis, northeastern North America. Note: This species is also known from MI & WI (Lohman, 1933). The cultures obtained by Lohman remained sterile, but he found empty associated pycnidia on the substrate.”

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Mytilinidion thujarum (Cooke & Peck) M.L Lohman. Photo credits © Alain Gardiennet. Left to right, top row: AG08OE21#, 11/10/2008, on Juniperus communis; AG09012#, 8/2/2009, on Juniperus communis; AG08AL15#, 27/4/2008 on Juniperus communis. Bottom row: AG09012# (spores); & AG09142#, 12/5/2009 on Cupressus sp. All from France.

Mytilinidion andinensis (Lorenzo & Messuti) E.W.A. Boehm, C.L. Schoch & J.W. Spatafora

Boehm, Schoch & Spatafora. Mycol. Res. 113: 470. 2009. comb. nov. MycoBank No.: MB 511997

Basionym: Hysterium andinense Messuti & Lorenzo, Mycological Research 101(3): 303. 1997.

Boehm et al. 2009a: “Messuti & Lorenzo (1997) described a new species of Hysterium from Patagonia, Argentina, collected from the bark of Austrocedrus chilensis (D. Don.) Florin & Boutlelje, designated as H. andinense Messuti & Lorenzo. However, molecular data presented here (Fig. 3) indicate that this taxon actually belongs to the genus Mytilinidion, in the Mytilinidiaceae, (Mytilinidiales) (Table 1). Although sections were not made, a re-examination of the original material, on which the single ascospore culture was based, showed fragile, thin-walled, globoid pseudothecia, with no prominent slit, enclosing a hamathecium of narrow trabeculate pseudoparaphyses, and three to seven (-nine) septate pigmented phragmospores, features congruent with the genus Mytilinidion”.

Messuti & Lorenzo (1997): “Hysterothecia scattered, erumpent, not branched, 0.6-1.3 x 0.22-0.45 x 0.4-0.64 mm, straight, striate. Pseudoparaphyses hyaline, sepate, branched to 1.5 μm diam. Asci cylindrical, 8-spored, 172-198 x 16-20 μm. Ascospores biseriate, fusiform, straight to slightly curved, first hyaline then greenish brown and guttulate when mature sienna, 3 – 7 (-9) septate, scarcely constricted at the septa with swollen middle cells, 32-44 x 10-15 μm”. Collected in the Andean-Patagonian forests, from the bark of Austrocedurs chilensis. The authors further state: “In agreement with these taxonomic criteria it has been established that the species related to H. andinense are H. insidens Schw. and H. sinense Teng. H. andinense is distinguished from the other related species by the fusiform, mainly five-septate spores. H. insidens differs from the new species by the ellipsoidal rusty, smaller spores, mainly with four or six transverse septa. When the spores have five septa they show a second swollen cell from the apical end; if the have six septa, then the swollen cell is the third from the apical end. H. seninse has ellipsoidal with seven transversal septa spores, and the cells are equal in size except the larger median cells. Those characters have been observed examining 55 mature specimens. As a conclusion of the analysis it could be affirmed that the septal range in each species is a reliable guide and a costant character to delimit species in Hysterium. Additonal differential features are observed in the ascomata and asci. In the three compared species the ascocarp length/width ratio is similar, but the average hysterothecia height of H. andinense is twice as large as or even larger than the average of H. insidens and H sinense. Furthermore, H. andinense has cylindrical asci, while the other two related species have claviform-cylindrical or claviform asci. The epithet andinense is deirived from the type locatily, Dina Huapi. The new species is so far known only from the type specimens”. From Boehm et al. (2009): ” Mytilinidion andinense (Messuti & Lorenzo) Boehm, Schoch & Spatafora comb nov.; MycoBank No.: MB 511997; Basionym: Hysterium andinense Messuti & Lorenzo, Mycological Research 101(3): 303. 1997. Remarks: Messuti & Lorenzo (1997) described a new species of Hysterium from Patagonia, Argentina, collected from the bark of Austrocedrus chilensis (D. Don.) Florin & Boutlelje, designated as H. andinense Messuti & Lorenzo. However, molecular data presented here, based on four nuclear genes, indicate that this taxon actually belongs to the genus Mytilinidion, in the Mytilinidiaceae, (Mytilinidiales). Although sections were not made, a re-examination of the original material, on which the single ascospore culture was based, showed fragile, thin-walled, globoid pseudothecia, with no prominent slit, enclosing a hamathecium of narrow trabeculate pseudoparaphyses, and three to seven (-nine) septate pigmented phragmospores, features congruent with the genus Mytilinidion“. The authors illustration in Figs. 1 & 2 (pg. 302) show a conchate fruitbody, and not a hysterothecium. This was confirmed in the material upon which the single-ascospore culture was derived in Boehm et al. (2009).






Mytilinidion andinensis (Lorenzo & Messuti) Boehm, Schoch & Spatafora.

Illustration credit: Eric W.A. Boehm (specimen EB 0330).


Mytilinidion decipiens (Karst.) Sacc.

Saccardo, Michelia I, 1877, 55.

Lophium decipiens Karst., 1871

Quite rare. Alpine belt in Europe. Also in the USA. From the living bark of Larix, Juniper Picea.

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.”





Mytilinidion decipiens (Karst.) Sacc. Zogg (1962), pgs. 105, 118.


Mytilinidion acicola Winter

Winter, Hedwigia, 19: 176. 1880.

Lophiostoma thujae Ellis & Everhart
Navicella thujae (Ellis & Everhart) Kuntze
Murashkinskiya juniperina Petrak

Rather common. Alpine Switzerland. Also collected from North America. From the living branches and twigs of Juniperus.

Barr (1990): “Ascomata elongate, scutate, 200 – 770 μm long, 150 – 385 μm wide, up to 550 μm at base, 165 – 275 μm high; peridium 15 – 30 um side at sides, thin at base. Asci (57-) 95 – 120 x 7.5 – 11 μm. Ascospores 14 – 22 (-28) x (4.5-) 6 – 8 9-10) μm, 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.”

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Mytilinidion acicola Winter. Photo credits © Alain Gardiennet. Specimens AG09097#, 8/4/2009,

on Juniperus communis. Note: scutate fruitbody base


Mytilinidion acicola Winter. Zogg (1962), pgs. 105, 120.

Mytilinidion californicum Ellis & Harkness 

Ellis & Harkness, Bull. Torrey Bot. Club 8: 51. 1881.

Hypodermopsis sequoiae Earle, 1902

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 500 μm long, 130 – 156 μm wide, 117 – 130 μm high, base widened; surface faintly longitudinally striate near margin; peridium ca. 15 μm wide at sides, pallid & narrow at base. Asci 50 – 60 x 8 – 10 μm. Ascospores 13 – 15 x 4 – 4.5 (-6) μm, yellowish brown, 3 – 5 – (6-) septate. [Note: It appears that there is a misprint here. Barr (1990) in her key gives the spore measurement as 23 – 25 x 4 – 4.5 (-5) μm. This is similar to the measurement given by Zogg (1962) in his key. Thus, the measurement given here by Barr (1990) as 13 – 15 x 4 – 4.5 (-6) may be a misprint]. 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, and the habitats also differ: Sequoia Sequoiadendron in the Taxodiaceae versus Juniperus or Thuja in the CupressaceaeMytilidion sequoiae Ellis & Harkness is an unpublished name that should be referred to M. californicum.”

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Mytilinidion californicum Elis & Harkness. Photo credits © Alain Gardiennet. AG09022#, France, 22/1/2009 collected from Libocedrus (Calocedrus decurrens).


Mytilinidion scolecosporum M.L. Lohman

Lohman, Mycologia 24: 480. 1932.

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.”



Mytilinidion scolecosporum M.L. Lohman. BPI #648713 COTYPE.

Collected by Alexander H. Smith, September 7th, 1930, from Pinus strobus wood, from Green Bay, Wisconsin.

Described as a new species by M.L. Lohman (1932b). Photo © E.W.A. Boehm. Illustration credits (right): pg. 480 in Lohman (1932b).


Mytilinidion parvulum M.L. Lohman

Lohman, Mycologia 24: 481. 1932

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.”



Mytilinidion parvulum M.L. Lohman. Illustration credit: pg. 480 in Lohman (1932b).


Mytilinidion australe M.L. Lohman

Lohman, Mycologia 24: 482. 1932.

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.”

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Mytilinidion australe M.L. Lohman, BPI #648676 COTYPE; Collected by Alexander H. Smith , Dec. 27th, 1931, from Pinus sp. wood, from Baton Rouge, Louisiana

& described as a new species by M.L. Lohman (1932b). Note: Extrememly wide, sessile conchate ascomata, with pronounced fan-shaped crests on lip margin;

very fragile, thin-walled peridia. © E.W.A. Boehm.





Mytilinidion australe M.L. Lohman. Illustration credits: pg. 480 in Lohman (1932b).