Postembryonic development of hard jaws (trophi) in a species belonging to theBrachionus plicatilis complex (Rotifera, Monogononta): A morphometric analysis

Fontaneto, Diego; Melone, Giulio

doi:10.1002/jemt.20319

Cited by 10 publications

(10 citation statements)

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“…Contrary to previous work dealing with morphological analyses of this species complex (e.g. Campillo et al, 2005;Fontaneto & Melone, 2006), here we did not select animals of known age, as our purpose was to find taxonomically useful differences, and taxonomists usually do not work with clonal cultures, but with animals directly collected in the field, where age cannot be controlled.…”

Section: Clone Selectionmentioning

confidence: 92%

“…As the position of trophi cannot be completely controlled during preparation, trophi may lie on either their dorsal or their ventral surfaces. We identified different landmarks to delimit measurements, following Fontaneto and Melone (2006), and then, we measured length of rami, unci, manubria, and external chambers of manubria, on both left and right sides when possible (Fig. 2).…”

Section: Trophi Shape and Sizementioning

confidence: 99%

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Disentangling the morphological stasis in two rotifer species of the Brachionus plicatilis species complex

et al. 2007

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The taxonomic uncertainty surrounding cryptic species complexes has traditionally been resolved using lengthy experimental approaches, while, since the advent of PCR based techniques the number of cryptic species described in a variety of taxa is increasing steadily.Here we formally describe a new rotifer species of the Brachionus plicatilis complex: Brachionus manjavacas n.sp., disentangling what was known as a morphological stasis. Detailed morphological analyses demonstrated significant differences in body shape and size between B. manjavacas and B. plicatilis s.s., analysed by geometric morphometrics; unfortunately these statistical differences are not taxonomically reliable because of wide overlaps. Size and asymmetry of masticatory apparatus, named trophi, observed by SEM, gave similar results, with taxonomic ambiguity. Only the shape of small pieces of the trophi, named satellites, were consistently different between the species. On a strictly classical taxonomical basis it is absolutely useful to name new species on morphological bases, as we did, and to assess their status as distinct entities. Nevertheless, the two species are broadly similar; therefore, we do not suggest using the small differences in shape of satellites of trophi to identify the species for further ecological studies, but to continue discriminating them on genetic marker bases.

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Section: Clone Selectionmentioning

confidence: 92%

Section: Trophi Shape and Sizementioning

confidence: 99%

Disentangling the morphological stasis in two rotifer species of the Brachionus plicatilis species complex

et al. 2007

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“…We measured length of the right ramus of trophi in caudal view. Rotifer trophi do not change in size with age (Fontaneto & Melone 2005, 2006); therefore, size may be considered species‐specific, or at least population‐specific. Differences in size among populations were analysed using an Analysis of Variance ( anova ) and Tukey Honestly Significantly Different (HSD) posthoc test.…”

Section: Methodsmentioning

confidence: 99%

On the reality and recognisability of asexual organisms: morphological analysis of the masticatory apparatus of bdelloid rotifers

Fontaneto¹,

Herniou²,

Barraclough³

et al. 2007

Zoologica Scripta

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On the reality and recognisability of asexual organisms: morphological analysis of the masticatory apparatus of bdelloid rotifers. -Zoologica Scripta , 36 , 361-370. Species concepts and definitions have been a long-standing debate in evolutionary biology since before Darwin, and almost all proposed solutions are based upon grouping and clustering, with species conceived as somehow biological distinct entities, originated and maintained mainly by reproductive isolation. Lacking reproductive exchange, asexual organisms such as bdelloid rotifers, the best-supported clade of so-called 'ancient asexuals', pose an interesting challenge to debates over the reality of species. However, few data are available on bdelloid rotifers. The only evidence has been that bdelloid species have been more consistently recognised than in their sister sexual group, the monogonont rotifers, across successive taxonomic treatments, but this is confounded by the much lesser degree of taxonomic interest in bdelloids. We applied geometric morphometrics analyses on shape and size of hard masticatory pieces, named trophi, of 1420 bdelloids, belonging to 48 populations of eight traditional species, to test the hypothesis of recognisability of bdelloids. Our morphological analysis confirms that traditional bdelloid species are separated distinct entities, possessing trophi morphologies divided by gaps between taxa, similar to patterns of morphological features in sexually reproducing organisms. In common with most microscopic understudied organisms, bdelloid rotifers harbour much previously undescribed diversity: we found significant differences in trophi morphology within traditional species, revealing the existence of cryptic taxa, similar to those also found in facultatively sexual monogonont rotifers. We confirm that recognisability in bdelloids is not qualitatively different from other small understudied animals such as monogononts, and that sexual versus asexual reproduction does not lead to differences in morphological diversity patterns, as previously suggested based on interpretation of taxonomic revisions.

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“…de Beauchamp (1951) reported that in Asplanchna, trophi of older embryos were not discernible from the trophi of their mother. In the youngest embryonic stages in which trophi could be detected, the trophi were smaller and compact, and became extended before their definitive sclerification; after sclerification, trophi did not grow any longer (but see Fontaneto et al 2003;Fontaneto & Melone 2005. Sørensen (2002) presented SEM pictures of embryonic trophi of Floscularia melicerta (EHRENBERG 1832), Filinia longiseta (EHRENBERG 1834), and Brachionus bidentatus ANDERSON 1889, but does not discuss them in detail.…”

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confidence: 99%

“…After hatching, ramate, malleate, virgate, forcipate, malleoramate, and uncinate trophi apparently do not change in size or shape (Fontaneto et al 2003;Fontaneto & Melone 2005, although some post-embryonic growth cannot be ruled out in some taxa with incudate trophi, such as Asplanchna priodonta GOSSE 1851 (Fontaneto et al 2003;Fontaneto & Melone 2005). Markevich (1985b) reported that embryos and new-born bdelloids, as a rule, have fewer unci teeth; this observation was confirmed for embryonic specimens of Rotaria rotatoria (PALLAS 1776) by Melone et al (1998).…”

mentioning

confidence: 99%

Ontogeny of the jaws of monogonont rotifers: the malleate trophi of Rhinoglena and Proalides (Ploima, Epiphanidae)

Smet

Segers

2017

Invertebrate Biology

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Information on the embryonic development of the malleate trophi in Epiphanidae (Rotifera, Monogononta, Ploima) is presented, based on scanning electron microscopy observations in Rhinoglena fertoeensis, R. frontalis, R. kutikovae, R. tokioensis, and Proalides tentaculatus, to contribute to the understanding of this structure of high evolutionary and functional relevance in Rotifera. The first observable and distinctly sclerotized structures were a double row of median transversal sclerites along the longitudinal axis, wherein the future unci, rostellar scleropili, cristae rami, and basal apophyses became recognizable. Fulcrum and manubria arose subsequently; the fulcrum sclerites were longitudinally ordered in a double layer. The rami chambers developed last as lamellar structures. Unci appeared as separate thin, elongate elements, the primary uncini, developing to uncus plates by transversal growth and apposition of sclerite material on the shafts of the uncini. The heads of the uncini showed their greatest development after fusion of their shafts into uncus plates. The interjacent spaces between the heads functioned as a mold, organizing bundles of sclerites which developed into the uniseriate, zigzag‐shaped cristae rami. The fulcrum attained its definite shape by elongation of the double layer of rod‐shaped sclerites into appressed sclerofibrillae. Manubria became visible as a proximal ridge of sclerites, whereupon a triangular lamella composed of crisscross‐oriented sclerites developed distally, growing out to the manubrial chambers. Ramus chambers originated from two longitudinal amorphous lamellae incorporating the median rami sclerites and closing from distal to proximal; subbasal chambers were formed before the basal chambers.

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Postembryonic development of hard jaws (trophi) in a species belonging to theBrachionus plicatilis complex (Rotifera, Monogononta): A morphometric analysis

Cited by 10 publications

References 37 publications

Disentangling the morphological stasis in two rotifer species of the Brachionus plicatilis species complex

Disentangling the morphological stasis in two rotifer species of the Brachionus plicatilis species complex

On the reality and recognisability of asexual organisms: morphological analysis of the masticatory apparatus of bdelloid rotifers

Ontogeny of the jaws of monogonont rotifers: the malleate trophi of Rhinoglena and Proalides (Ploima, Epiphanidae)

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