系统发育分析显示，在美洲蜥蜴中发现的 Schellackia 寄生虫（顶复门）与 Lankesterella 属密切相关：Schellackia 的分布范围是否仅限于旧世界？
Phylogenetic analyses reveal that Schellackia parasites (Apicomplexa) detected in American lizards are closely related to the genus Lankesterella: is the range of Schellackia restricted to the Old World?
机构信息
Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain.
Departamento de Biomedicina y Biotecnología, Área de Parasitología, Universidad de Alcalá de Henares, Alcalá de Henares, Spain.
出版信息
Parasit Vectors. 2017 Oct 10;10(1):470. doi: 10.1186/s13071-017-2405-0.
BACKGROUND
Species of Schellackia Reichenow, 1919 have been described from the blood of reptiles distributed worldwide. Recently, Schellackia spp. detected in European and Asian lizards have been molecularly characterised. However, parasites detected in American lizard hosts remain uncharacterised. Thus, phylogenetic affinities between the Old and New World parasite species are unknown.
METHODS
In the present study, we characterised morphologically and molecularly the hemococcidian parasites (sporozoites) that infect three lizard hosts from North America and two from South America.
RESULTS
In total, we generated 12 new 18S rRNA gene sequences of hemococcidian parasites infecting New World lizard hosts. By the microscopic examination of the smears we identified Schellackia golvani Rogier & Landau, 1975 (ex Anolis carolinensis Voigt) and Schellackia occidentalis Bonorris & Ball, 1955 (ex Uta stansburiana Baird & Girard and Sceloporus occidentalis Baird & Girard) in some samples, but the phylogenetic analysis indicated that all 18S rDNA sequences are distant from Schellackia species found in Old World lizards. In fact, the hemococcidian parasites detected in the New World lizards (including S. occidentalis and S. golvani) were closely related to the genus Lankesterella Labbé, 1899. Consequently, we suggest these two species to be included within the genus Lankesterella.
CONCLUSIONS
Life history traits of hemococcidian parasites such as the type of host blood cells infected, host species or number of refractile bodies are not valid diagnostic characteristics to differentiate the parasites between the genera Schellackia and Lankesterella. Indeed, lankesterellid parasites with a different number of refractile bodies had a close phylogenetic origin. Based on the phylogenetic results we provide a systematic revision of the North American hemococcidians. Our recommendation is to include the species formerly described in the genus Schellackia that infect American lizards into Lankesterella (Lankesterellidae) as Lankesterella golvani (Rogier & Landau, 1975) n. comb and L. occidentalis (Bonorris & Ball, 1955) n. comb.
背景
1919 年，Reichenow 描述了分布在世界各地的爬行动物血液中的 Schellackia 物种。最近，在欧洲和亚洲蜥蜴中检测到的 Schellackia 物种已通过分子特征进行了描述。然而，在美洲蜥蜴宿主中检测到的寄生虫仍未得到描述。因此，新旧世界寄生虫种之间的系统发育关系尚不清楚。
方法
在本研究中，我们对来自北美的三种蜥蜴宿主和南美的两种蜥蜴宿主感染的血腔球虫（裂殖子）进行了形态和分子特征描述。
结果
总共生成了 12 个新的感染新世界蜥蜴宿主的血腔球虫 18S rRNA 基因序列。通过对涂片的显微镜检查，我们在一些样本中鉴定出 Schellackia golvani Rogier & Landau, 1975（原 Anolis carolinensis Voigt）和 Schellackia occidentalis Bonorris & Ball, 1955（原 Uta stansburiana Baird & Girard 和 Sceloporus occidentalis Baird & Girard），但系统发育分析表明，所有 18S rDNA 序列都与旧世界蜥蜴中发现的 Schellackia 物种相距甚远。实际上，在新世界蜥蜴（包括 S. occidentalis 和 S. golvani）中检测到的血腔球虫与 Lankesterella Labbé, 1899 属密切相关。因此，我们建议将这两个物种归入 Lankesterella 属。
结论
血腔球虫的生活史特征，如感染的宿主血细胞类型、宿主物种或折射体数量，不是区分 Schellackia 和 Lankesterella 属寄生虫的有效诊断特征。事实上，折射体数量不同的 Lankesterella 属寄生虫具有密切的系统发育起源。基于系统发育结果，我们对北美的血腔球虫进行了系统修订。我们的建议是将以前描述的感染美洲蜥蜴的 Schellackia 属物种归入 Lankesterella（Lankesterellidae），即 Lankesterella golvani（Rogier & Landau, 1975）n. comb 和 L. occidentalis（Bonorris & Ball, 1955）n. comb。
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