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The general muscular architecture in Tubiluchus troglodytes (Priapulida). Meiofauna Marina
No full textWe describe here the general muscular architecture of Tubiluchus troglodytes (Priapulida) based on phalloidin staining, confocal laser scanning and transmission electron microscopy. The body wall musculature is composed of a grid of circular and longitudinal muscle bundles, in the introvert, there is additional outer longitudinal musculature. T. troglodytes has pharynx protractors, wheras the introvert retractors could not be sufficiently resolved in this investigation. The muscular pharynx is followed by an organ with solid circular musculature, the polythyridium. The body wall musculature proceeds into the long tail. In the posterior region, anus and urogenital pores are surrounded by circular musculature
Macroecology and meiobenthos: Reply to Warwick (2014)
Full text linkWarwick (2014; Mar Ecol Prog Ser 505:295-298) suggests that my claim that the biology of marine metazoan benthos may scale continuously with body mass (Bett 2013; Mar Ecol Prog Ser 487:1-6) is an overstatement. His alternative hypothesis is that there is a ‘step-change’ in allometric relationships between the meio- and macrobenthos. I continue to propose that simple null hypotheses for standing stock size spectra and species size spectra of the metazoan benthos, consistent with metabolic theory and macroecology, offer parsimonious solutions. For standing stock and species size spectra I present field data that conform to these null hypotheses. Data from other studies, such as those suggested by Warwick (2014), may be difficult to place in the macroecological context, as those studies are constructed or presented in a different manner (e.g. they lack data on the number of individuals identified). I suggest that it may be useful to consider ‘evolutionary species size spectra’ separately from ‘macroecological species size spectra’. Both are valid testable hypotheses, and are not necessarily contradictory
Figure 4 in Revision of the genus Chordodes (Gordiida, Nematomorpha) from Africa-I. Ultrastructural redescription of Chordodes gariazzi Camerano, 1902, C. heinzei Sciacchitano, 1937, C. kolensis Sciacchitano, 1933, C. muelleri Sciacchitano, 1937, and C. ruandensis Sciacchitano, 1937
No full textFigure 4. Chordodes muelleri, female. (A) Stereomicroscope, posterior end with terminal cloacal opening (arrow); (B) body cuticle with simple (1) and tubercle areoles (2); (C) clusters containing crowned (3) and circumcluster (4) areoles; (D) cluster of crowned areoles with long filaments (5) along the ventral midline. Scale bars: 16.6 mm (A); 10 mm (B, C).Published as part of Zanca, F., Villalobos, C. De & Schmidt-Rhaesa, A., 2006, Revision of the genus Chordodes (Gordiida, Nematomorpha) from Africa-I. Ultrastructural redescription of Chordodes gariazzi Camerano, 1902, C. heinzei Sciacchitano, 1937, C. kolensis Sciacchitano, 1933, C. muelleri Sciacchitano, 1937, and C. ruandensis Sciacchitano, 1937, pp. 17-31 in Journal of Natural History 40 (1-2) on page 27, DOI: 10.1080/00222930600617898, http://zenodo.org/record/522664
Two steps to suicide in crickets harbouring hairworms
No full textSanchez MI, Ponton F, Schmidt-Rhaesa A, Hughes DP, Misse D, Thomas F. Two steps to suicide in crickets harbouring hairworms. Animal Behaviour. 2008;76(5):1621-1624
The musculature of three species of gastrotrichs surveyed with confocal laser scanning microscopy (CLSM)
No full textThe muscular system of gastrotrichs consists of circular, longitudinal and helicoidal bands that when analysed with confocal laser scanning microscopy, provide new insights into their functional organization and phylogenetic importance. We therefore undertook a comparative study of the muscle organization in three species of Gastrotricha from the orders Macrodasyida (Paradasys sp., Lepidodasyidae; Turbanella sp., Turbanellidae) and Chaetonotida (Polymerurus nodicaudus, Chaetonotidae). The general muscle organization of the marine interstitial macrodasyidans, Paradasys and Turbanella, not only confirms earlier observation on other species but also adds new details concerning the organization and number of helicoidal, longitudinal and other muscle bands (e.g. semicircular band). The freshwater, epibenthic-epiphytic chaetonotid, Polymerurus nodicaudus, has a similar muscular organization to other species of Chaetonotidae, especially species of Chaetonotus, Halichaetonotus and Lepidodermella. Perhaps unique to Polymerurus is the combined presence of an unbranched Ruckenhautmuskel (also in Halichaetonotus and Lepidodermella) and a specialized dorsoventral caudal muscle, which flank the splanchnic component of the longitudinal muscles (only in Chaetonotus and Lepidodermella). This combination, together with the presence of splanchnic dorsoventral muscles, known only in Xenotrichulidae, implies a unique phylogenetic position for Polymerurus, and indicates a potential basal position of this taxon among the Chaetonotidae studied so far (i.e. Aspidiophorus, Chaetonotus, Halichaetonotus and Lepidodermella)
Figure 3 in Revision of the genus Chordodes (Gordiida, Nematomorpha) from Africa-I. Ultrastructural redescription of Chordodes gariazzi Camerano, 1902, C. heinzei Sciacchitano, 1937, C. kolensis Sciacchitano, 1933, C. muelleri Sciacchitano, 1937, and C. ruandensis Sciacchitano, 1937
No full textFigure 3. Chordodes kolensis. (A) Stereomicroscope, male posterior end, subterminal cloacal opening (arrow) (AMT 1400). (B–G) SEM: (B) female posterior end with terminal cloacal opening (arrow) (AMT 1390); (C–F) cuticle from male specimens; (C) general view of the midbody cuticle; (D) higher magnification from (C); (E) additional areolar types (labelled 3 and 4); (F) crowned areoles with short filaments from the lateral body sides; (G) female crowned areoles with long apical filaments from the ventral midline. Numbering: simple (1), bulging (2), special types (3, 4), crowned with short filaments (5), circumcluster (6), and crowned with long filaments (7) areoles. Scale bars: 16.6 mm (A); 100 mm (B, C); 25 mm (D); 10 mm (E, F); 50 mm (G).Published as part of Zanca, F., Villalobos, C. De & Schmidt-Rhaesa, A., 2006, Revision of the genus Chordodes (Gordiida, Nematomorpha) from Africa-I. Ultrastructural redescription of Chordodes gariazzi Camerano, 1902, C. heinzei Sciacchitano, 1937, C. kolensis Sciacchitano, 1933, C. muelleri Sciacchitano, 1937, and C. ruandensis Sciacchitano, 1937, pp. 17-31 in Journal of Natural History 40 (1-2) on page 24, DOI: 10.1080/00222930600617898, http://zenodo.org/record/522664
Sciacchitano, 1958
No full textFigure 5. Holotype of Chordodes mobensis. (A) Cuticle showing simple, bulging and thorn areoles; (B) thorn areole (double arrow) and tubercle areole (white arrow); (C) clusters containing crowned areoles; (D) midline of the body showing crowned areoles with short filaments and thorn areoles. Scale bars: 20 µm (A), 10 µm (B, C).Published as part of Villalobos, C. De, Zanca, F. & Schmidt-Rhaesa, A., 2009, Revision of the genus Chordodes (Gordiida: Nematomorpha) from Africa IV. Ultrastructural redescription of Chordodes congolensis Sciacchitano, 1933, Chordodes ferox Camerano, 1897, Chordodes madagascariensis (Camerano, 1893), Chordodes mobensis Sciacchitano, 1958 and reinterpretation of Chordodes maculatus Sciacchitano, 1958 and Chordodes kakandensis Sciacchitano, 1958, pp. 2579-2595 in Journal of Natural History 43 (41-44) on page 2589, DOI: 10.1080/00222930903220002, http://zenodo.org/record/521795
Redescription of Xenodasys riedli (Gastrotricha: Macrodasyida) based on SEM analysis, with first report of population density data
No full textDuring surveys of the Gastrotricha of the Tropical Northwestern Atlantic (TNWA, Caribbean Sea), we came across numerous specimens of the uncommon
macrodasyidan, Xenodasys riedli (Xenodasyidae). Abundance data on gastrotrichs is rare and entirely absent for this species; moreover, there are no data on morphological variation of X. riedli outside its type locality (North Carolina, USA). Here, we provide new abundance data on specimens collected from St. John Island (US Virgin Islands), as well as new metric and morphological data from specimens collected on San Salvador Island (Bahamas), Tobago, and a sublittoral environment on the Atlantic Coast of Florida (USA). In the interstitial environments of St. John, X. riedli was most abundant at 0.8 m depth in moderately well-sorted sediments. It reached maximum abundance of 89.5 ± 42.7 ind./102 cm and made up 69.7% of the total taxocoenosis. Metric variation revealed that specimens at all sites in the TNWA and Florida had smaller body sizes than those recorded at the type locality, but showed only limited variation in the size and number of taxonomic characters. Observations of specimen from Florida using scanning electron microscopy (SEM) revealed details that were overlooked in the type description. For example, we observed 8 dorsal head plates (11 in the original description), 1 pair of anterior medial plates, and 3 ventral
plates, the latter of which were not described in the type specimens. We confirm the existence of round scales on the dorsolateral margins, and note that spineless-scales are also present in between the spined scales on the lateral body wall. We also determined that the lateral spined scales possess dorsal
and ventral spines instead of anterior and posterior spines, which was their original assumed position. This research reveals that SEM remains the best diagnostic tool for characterizing gastrotrich morphology, and should be part of all future studies of gastrotrich taxonomy
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