a Institute of Microbiology, Czech Academy of Sciences , v.v.i, Vídeňská 1083, 142 20 Prague 4 , Czech Republic.
b School of Forest Resources and Conservation , University of Florida , PO Box 110410, Gainesville , Florida 32611.
Mycologia. 2017;109(2):185-199. doi: 10.1080/00275514.2017.1303861. Epub 2017 Apr 24.
Fungi in the genus Geosmithia (Ascomycota: Hypocreales) are frequent associates of bark beetles and woodborers that colonize hardwood and coniferous trees. One species, Geosmithia morbida, is an economically damaging invasive species. The authors surveyed the Geosmithia species of California and Colorado, USA, to (i) provide baseline data on taxonomy of Geosmithia and beetle vector specificity across the western USA; (ii) investigate the subcortical beetle fauna for alternative vectors of the invasive G. morbida; and (iii) interpret the community composition of this region within the emerging global biogeography of Geosmithia. Geosmithia was detected in 87% of 126 beetle samples obtained from 39 plant species. Twenty-nine species of Geosmithia were distinguished, of which 13 may be new species. Bark beetles from hardwoods, Cupressus, and Sequoia appear to be regular vectors, with Geosmithia present in all beetle gallery systems examined. Other subcortical insects appear to vector Geosmithia at lower frequencies. Overall, most Geosmithia have a distinct level of vector specificity (mostly high, sometimes low) enabling their separation to generalists and specialists. Plant pathogenic Geosmithia morbida was not found in association with any other beetle besides Pityophthorus juglandis. However, four additional Geosmithia species were found in P. juglandis galleries. When integrated with recent data from other continents, a global pattern of Geosmithia distribution across continents, latitudes, and vectors is emerging: of the 29 Geosmithia species found in the western USA, 12 have not been reported outside of the USA. The most frequently encountered species with the widest global distribution also had the broadest range of beetle vectors. Several Geosmithia spp. with very narrow vector ranges in Europe exhibited the similar degree of specialization in the USA. Such strong canalization in association could reflect an ancient origin of each individual association, or a recent origin and a subsequent diversification in North America.
地衣孢属（子囊菌门：Hypocreales）真菌是经常与树皮甲虫和蛀木甲虫有关的，这些甲虫会在硬木和针叶树上定殖。有一种物种，即地衣孢属 morbidus，是一种具有经济破坏性的入侵物种。作者调查了美国加利福尼亚州和科罗拉多州的地衣孢属物种，以（i）提供关于地衣孢属分类学和甲虫载体特异性的基础数据，跨越美国西部；（ii）研究次皮层甲虫动物群中入侵的 G. morbida 的替代载体；以及（iii）解释该地区在新兴的地衣孢属全球生物地理学中的群落组成。从 39 种植物中获得的 126 个甲虫样本中，有 87%检测到地衣孢属。区分出 29 种地衣孢属物种，其中 13 种可能是新物种。来自硬木、柏木和红杉的树皮甲虫似乎是常规载体，在所有检查的甲虫画廊系统中都存在地衣孢属。其他次皮层昆虫似乎以较低的频率传递地衣孢属。总体而言，大多数地衣孢属具有明显的载体特异性（主要是高，有时是低），使其能够分离为广义和专门的载体。除了 Pityophthorus juglandis 之外，未在地衣孢属 morbida 中发现与任何其他甲虫有关。然而，在 P. juglandis 画廊中发现了另外四种地衣孢属物种。当与来自其他大陆的最新数据整合时，地衣孢属在全球范围内的分布模式正在出现：在美国西部发现的 29 种地衣孢属物种中，有 12 种尚未在美国以外的地区报告。最常遇到的具有最广泛全球分布的物种也具有最广泛的甲虫载体范围。在欧洲具有非常狭窄载体范围的几种地衣孢属物种在美国也表现出类似的专业化程度。这种强烈的关联可能反映了每个单独关联的古老起源，或者是北美的近期起源和随后的多样化。
