A new rust fungus was found on Lygodium flexuosum at Doi Suthep-Pui National Park in Chiang Mai Province, Thailand. Puccinia lygodii was the only rust fungus currently known on Lygodium spp. (Lygodioideae, Schizaeaceae, Schizaeales) from southern North America through northern South America. The new fungus produced uredinia linearly between veins, causing yellowish streaks, on the abaxial frond surface. The sori were covered with a layer of thin-walled fungal cells beneath the host epidermis and surrounded by thin-walled paraphyses. The sori did not have a distinct central aperture with ostiolar cells but ruptured irregularly to release urediniospores. Urediniospores were obovoid, obovoid-ellipsoid, or pyriform. The wall was thin, colorless, and completely echinulate. Neither amphispores nor teliospores were observed. The sorus and spore morphology indicated the taxonomic affinity of the fungus to the fern rust genera Hyalopsora and Milesina. A molecular phylogenetic analysis using nuclear large subunit ribosomal DNA sequence revealed that the Lygodium rust fungus was grouped in a paraphyletic Milesina clade. From the putative host preference, morphology, and estimated phylogenetic relationships, it was concluded that the fungus was a new species of Milesina.

中文翻译：

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Milesina thailandica，在泰国发现的早期分化的细孢子管蕨属Lygodium上的第二个锈菌

在泰国清迈府素贴山国家公园的屈指藻上发现了一种新的锈菌。紫草是目前在Lygodium上已知的唯一防锈真菌spp。北美南部到南美北部的植物（Lygodioideae，Schizaeaceae，Schizaeales）。这种新真菌在叶脉间线性地产生了尿素，导致淡黄色条纹。宿主的表皮下覆盖着一层薄壁真菌细胞，周围被薄壁附生植物所覆盖。鼻窦没有明显的中央孔，但有心房细胞，但不规则地破裂而释放出乌头孢子。Urediniospores是卵球形，卵球形椭圆形或梨形。墙壁是薄的，无色的，完全弹力。均未观察到两栖孢子或末端孢子。孢子形态和形态表明真菌对蕨类锈菌Hyalopsora和Milesina的分类学亲和力。利用核大亚基核糖体DNA序列的分子系统发育分析，发现该海金沙锈菌是在一个分组并系Milesina进化枝。从推定的寄主偏好，形态和估计的系统发生关系，可以得出结论，该真菌是Milesina的新种。