Ricania speculum (Walker, 1851)
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https://dx.doi.org/10.3897/zookeys.880.32810 |
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lsid:zoobank.org:pub:EFFE7128-E4A2-42F6-84CE-0BDDD5E0A447 |
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https://treatment.plazi.org/id/82A056D0-D45E-54A4-BD54-516AECC8BEC9 |
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Ricania speculum (Walker, 1851) |
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Ricania speculum (Walker, 1851) View in CoL
Description.
Mature spermatozoa of R. speculum are similar to those of P. shantungensis in morphology insofar as they also have a number of spermatozoa (totally 128 spermatozoa per spermatodesm) organized into sperm bundles with their heads embedded in a homogenous matrix ( Fig. 5A, C–D View Figure 5 ). The individual sperm is filiform, measuring 196 µm in average length ( Fig. 5B View Figure 5 ), with a linear head and distinct flagellum, approximately 24 µm and 172 µm in length, respectively.
The sperm head of R. speculum is elongated and filiform, formed by a short acrosome and an elongated nucleus ( Figs 5B View Figure 5 , 6B View Figure 6 ). The conical acrosome contains a dothideoid acrosomal vesicle and perforatorium with the latter made of electron-dense fiber substructures ( Fig. 6B View Figure 6 ). A transition region is visible between the acrosome and the anterior portion of the nucleus ( Fig. 6B View Figure 6 ). Anteriorly the nucleus is surrounded by the acrosome which is filled with numerous fibrous substructures; posteriorly it increases in diameter and changes from a mushroom-shape to a meniscus shape and finally to an oval-shape ( Fig. 7 B–D View Figure 7 ). The nucleus, approximately 0.99 µm in diameter, is filled with compact chromatin and takes on different shapes ( Figs 6C View Figure 6 , 7 B–I View Figure 7 ).
In the nucleus-flagellum transition region, the centriole and centriolar adjunct that lie next to the nucleus are abrupt ( Fig. 6A, C View Figure 6 ). The centriole is formed by dense microtubules that originate from the end of the pyknotic nucleus and end above the front of the axoneme ( Figs 6B View Figure 6 , 7 G–H View Figure 7 ). The centriolar adjunct is composed of moderate electron-dense substances, connecting mitochondrial derivatives with the nucleus ( Figs 6B View Figure 6 , 7 E–I View Figure 7 ).
The cross-section of the flagellum region consists of an axoneme, two symmetrical accessory bodies and two mitochondrial derivatives ( Fig. 8A, B View Figure 8 ). The axoneme of the flagellum of R. speculum has a typical 9 + 9 + 2 microtubule pattern, comprised of two central microtubules, nine inner doublet microtubules and nine outermost single accessory microtubules ( Fig. 8C View Figure 8 ). The mitochondrial derivatives have evident parallel cristae arranged in the periphery and are formed by three different portions: a serrated electron-dense region, a central clear area and a mitochondrial cristae region ( Fig. 8B View Figure 8 ). The cristae are perpendicular to the axis of the derivatives and are at regular intervals (about 46 nm) between adjacent derivatives ( Fig. 6D View Figure 6 ). Between the axoneme and the mitochondrial derivatives are large, fishhook-shaped accessory bodies ( Fig. 8A, B View Figure 8 ); they are composed of electron-dense material ( Fig. 8B View Figure 8 ). Close to the posterior sperm tip, the mitochondrial derivative is first to end ( Fig. 8E View Figure 8 ), followed by the accessory bodies, while the axoneme gradually becomes disorganized ( Fig. 8B, D–F View Figure 8 ).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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