Dondersiidae, Simroth, 1893
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publication ID |
https://doi.org/ 10.1007/s13127-016-0266-6 |
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persistent identifier |
https://treatment.plazi.org/id/46578799-FF82-F332-BD50-FAC1FB8AFBCD |
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treatment provided by |
Felipe |
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scientific name |
Dondersiidae |
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All material that we extracted from sand samples externally showed the scleritome typical for Meiomeniidae , i.e., with at least three different types of scales including lanceolate ones projecting laterally (see Fig. 1a View Fig ). Meiomeniidae is also characterized, however, by a distichous radula and a comparably simple arrangement of foregut glands (B Meioherpia - type^ in Handl and Todt 2005), which is clearly opposed by the monostichous (=monoserial) radula and the complex foregut glands (three types of pharyngeal glands and an unusual ventrolateral foregut gland complex with conspicuous pouches) detected in two of the individuals. Monoserial radulae are characteristic for several families of Solenogastres (e.g., Dondersiidae , Macellomeniidae , and Acanthomeniidae ) and the majority of the ten amphimeniid genera ( García-Álvarez and Salvini-Plawen 2007). But in combination with the scaly scleritome lacking hollow needle-like sclerites, the cryptic lineage encountered in Bermuda sands currently can be best assigned to Dondersiidae . Monophyly of Dondersiidae is poorly supported, and the taxon currently serves as a B catch basin^ for several lineages with similar radula and scleritome morphology ( Scheltema et al. 2012). The generic classification of our dondersiid-like specimens from Bermuda remains unclear as putative small denticles of the radula cannot be reliably reconstructed based on histological section series and no material remains for SEM studies of the radula. The complex system of different types of pharyngeal glands and unique ventrolateral foregut glands with conspicuous pouches are unique for any of the described genera of Dondersiidae , and a similar setting is so far only known from a recently described species from the Azores provisionally classified within Dondersia ( Klink et al. 2015) . Neither the family nor the generic classification of the species from the Azores and its putative close relative encountered in the course of the present study in Bermuda are without conflict to established character sets characterizing these taxonomic entities (e.g., presence of a pedal comissural sac, unique ventrolateral forgut glands with pouches). We refrain from establishing novel categories, until gaps in the data matrix of the mysterious novel lineages can be filled and until Dondersiidae are comparatively reinvestigated also with the support of molecular markers. Therefore, we further abstain from formally describing the discovered novel lineage herein, as (1) detailed ultrastructural data on the scleritome cannot be reliably assigned between the comicroscopic image of one column of radula teeth from meiomeniid M3. Note large lateral denticle (black arrowhead) and three smaller median denticles (asterisks). Abbreviations: bg buccal ganglion, dc dorsal caecum of midgut, fgl ventrolateral foregut glands, ft foot, ln lateral nerve cord, pg pedal ganglia, ph pharynx, r radula occurring lineages, (2) the two single individuals are juveniles lacking a description of the gonopericardial system and above all, and (3) no material remains for molecular analyses. A formal taxonomic description is postponed until more material is available to fill these gaps.
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