Xyleborus sporodochifer R.C.Harris & Ladd

Description

Type: - USA. MISSOURI. BARRY CO.: Mark Twain National Forest, Piney Creek Wilderness, north of Forest service Road #2185, 4.0 miles east of MO #39, Siloam Spring Trail, elev. 1200–1300 ft., 36°39'54"N, 93°36'23"W, oak-pine forest with chert residuum, on wood, 27.iii.2006, Lendemer 6519 (NY, holotype; isotypes to be distributed as Lendemer, Lichens of Eastern North America Exsiccati V: 228).

Description: (From Harris & Ladd 2007) - Thallus visible as paler areas on weathered decorticate logs and stumps (always Quercus?), patchy but often common on an individual log, superficial, scanty to abundant, pale tan to olivaceous, rough, of small (0.1 mm), areoles initially, sometimes remaining scattered but often coalescing and becoming +/- continuous when thallus well developed; prothallus not evident; photobiont chlorococcoid, cells globose, 10-14 µm; unknown substance in low concentration or no lichen substances detected. Apothecia initially discoid, mostly becoming swollen, hemispherical to +/-turbinate, constricted at base, sometimes weakly stipitate, 0.2-0.5-(0.8) mm across, 0.1-0.3 mm high; disk brown to dark brown or nearly black but often with thin whitish pruina (dissolving in K), sometimes appearing gray when pruina "immersed"; margin not raised, concolorous or slightly darker than disk, not evident in swollen apothecia. Exciple almost colorless to pale brown outward, brown inward, 50.80 µm thick, of adnate radiating hyphae in colorless gel which forms a distinct external layer, sometimes containing +/- linear pockets of colorless crystals (dissolving in K); inner exciple adjacent to hypothecium with radiating lines of amorphous, dark brown extra-hyphal pigment to densely pigmented as in hypothecium; excipular hyphae mostly +/- expanded at tips (to 5.5 µm). Epihymenium almost colorless to brownish, with numerous small colorless crystals (dissolving in K). Hymenium usually tinted pale to medium brown or brown streaked, 50-80 µm high. Paraphyses some slender, ca. 1.1.5 µm across, unbranched or branched once in upper part, not expanded or pigmented at tips, interspersed with few to many with expanded tips to 3.5 µm broad and with a thin brown cap. Hypothecium dark brown, 50 µm high in young apothecia to ca. 200 µm in older, swollen apothecia (constituting bulk of apothecium), of very irregular and contorted hyphae, filled with dark brown extra-hyphal pigment and sometimes colorless crystals, K-intensifying. Asci Micarea-type, clavate, with 8 irregularly arranged spores. Ascospores simple, fusiform to ovoid, colorless, 7-8.3-10.5 x 3.5-3.9-4.5 µm, without halo. Sporodochia white, hemispherical to subglobose, 0.1.1.5(.2) mm across, K+ pale yellow; sterile part of colorless, irregular, tightly entwined, short-celled hyphae on a base of looser, brown hyphae/bark; conidiogenous cells poorly differentiated, short, irregular. Conidia globose, 2.5.4 µm across, forming short, irregular chains/groups.

Etymology: (From Harris & Ladd 2007) - Xyleborus = eating wood; sporodochifer = bearing sporodochia.

Distribution and ecology: (From Harris & Ladd 2007) - Xyleborus occupies an unusually narrow niche. It is confined to weathered lignum near ground level in shaded woodlands, typically in dry-mesic to dry habitats, but less commonly in mesic areas. It appears to be restricted to intact woodlands. Most, and perhaps all, of the records are from Quercus, usually on fallen logs but occasionally on the side of stumps. The substrate is always weathered and/or decayed to the point beings rough and abundantly fissured and cross-checked with cracks, but generally not decayed to the point of punkiness. Xyleborus is common in the Ozarks with a single record from eastern Kansas.

Discussion: (From Harris & Ladd 2007) - As a consequence of the restricted circumscription of Lecidea Ach. s. lat., all but a single Ozark species of Lecidea have been placed in other genera or belong to as yet undescribed genera. Since the other two unnamed lecideoid groups in our area (the cyrtidia–plebeja group and the hypnorum group) are widespread and, perhaps, controversial as to their disposition, we restrict ourselves to describing this unique, near-endemic Ozark species. As far as we are aware lichens with sporodochial anamorphs are extremely rare (Micarea adnata Coppins, Coppins, 1983; Tylophoron Stizenb., Tibell, 1982, Harris, 1995) as are synnematal anamorphs (Dictyocatenulata Finley & E. F. Morris, Lendemer & Harris, 2004). The vast majority produce pycnidia or hyphophores. While the presence of sporodochia (sometimes collected without accompanying apothecia) makes identification simple and provides additional justification for the new genus, the teleomorph is morphologically distinct. Xyleborus shares lignicolous substrate, apothecial coloration (external and internal) and Micarea-type ascus with species of Hertelidea Printzen & Kantvilas and "Lecidea" plebeja Nyl. The most obvious distinctions from both of the latter are found in the exciple, i.e., the colorless layer of gel on the outside and the rather narrow, closely adnate excipular hyphae with relatively unexpanded tips (differing from broader hyphae with distinctly expanded terminal cells). Micarea adnata differs in having the sporodochia composed of thin, cylindrical conidiogenous cells bearing small, simple conidia and in having apothecia with a poorly developed exciple.

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Tripp5480_photoLendemer_01 (image/jpeg)

Tripp5480_photoLendemer_02 (image/jpeg)

Tripp5480_photoLendemer_03 (image/jpeg)