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<i>Saprolegnia</i>, a notable genus within the <i>Saprolegniales</i>, is known for its pathogenic tendencies on a wide range of aquatic organisms, causing infections such as saprolegniasis and Epizootic Ulcerative Syndrome (EUS). From late 1985 to early 1986, accounts of local periodic EUS outbreaks were reported. However, the infection has primarily been associated with <i>Aphanomyces</i> sp., another genus within the same order, rather than <i>Saprolegnia</i> sp. The only species from this genus documented in the country thus far is <i>Saprolegnia diclina</i>, with the last recorded isolation occurring sixty years ago. No member of the genus has been isolated, much less rediscovered, since then. It is speculated that its rarity is due to elevated temperatures in the Philippines, which created unfavorable conditions for its growth. Considering this, the study deliberately targeted a remote highland area with low temperatures, specifically in Kibungan, Benguet, Philippines, in search of cold-dwelling <i>Saprolegnia</i> species in the tropics. Two isolates, collected from muddy water samples baited using sesame seeds, underwent morphological, physiological, and molecular analyses and were identified as <i>Saprolegnia ferax</i>. Further, the findings emphasize the importance of temperature as a key growth and dispersal factor as the isolates thrive within the range of 15 ºC to 30 ºC yet exhibit limited growth at temperatures equal to or beyond 35ºC. This paper describes the second <i>Saprolegnia </i>report for the Philippines.

水霉属（Saprolegnia）是隶属于水霉目（Saprolegniales）的重要类群，可侵染多种水生生物并引发水霉病及流行性溃疡综合征（Epizootic Ulcerative Syndrome, EUS）。1985年末至1986年初，当地曾有周期性流行性溃疡综合征暴发的报道，但彼时该病害主要被认为与同目下的丝囊霉属（Aphanomyces）物种相关，而非水霉属物种。目前该国已记录的水霉属物种仅为双游水霉（Saprolegnia diclina），最后一次分离记录可追溯至60年前，此后再未分离到该属的任何物种，亦未曾重新发现过。有研究推测，菲律宾地区的高温环境不利于其生长，导致该属物种较为罕见。基于此，本研究特意选取了菲律宾本格特省基邦甘这一低温偏远高地，以搜寻热带地区的嗜冷水生水霉属物种。研究团队以芝麻种子为诱饵采集泥水样本，成功分离得到两株菌株，经形态学、生理学及分子生物学分析后，鉴定为强壮水霉（Saprolegnia ferax）。进一步研究结果证实，温度是影响该属菌株生长与扩散的关键因素：受试菌株可在15℃至30℃的范围内良好生长，但在35℃及以上温度下生长受限。本文为菲律宾地区第二例水霉属物种的相关报道。