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Echinoidea name detailsGymnechinus megaloplax H.L. Clark, 1912
762369 (urn:lsid:marinespecies.org:taxname:762369)
unaccepted (subjective junior synonym)
Species
marine,
recent only
Clark, H. L. (1912). Hawaiian and other Pacific Echini. The Pedinidae, Phymosomatidae, Stomopneustidae, and Echinometridae. <em>Memoirs of the Museum of Comparative Zoölogy at Harvard College.</em> 34/4: 205-383., available online at https://www.biodiversitylibrary.org/page/1325954
page(s): 287-288; pl. 102: figs 2-3 [details]
Holotype MCZ 1291, geounit Persian Gulf
Holotype MCZ 1291, geounit Persian Gulf [details]
Status Further, there can be no doubt that the Gymnech. megaloplax of H. L. Clark is only a synonym of G. Robillardi. The main...
Status Further, there can be no doubt that the Gymnech. megaloplax of H. L. Clark is only a synonym of G. Robillardi. The main character of this species is the large "suranal" plate (Fig. 265). But it is fairly certain that it is merely an anomalous subdivision of the genital plates which has occurred in this specimen. Exactly the same anomaly may be found in G. pulchellus, cf. fig. 268, a; p. 428, such specimens being in all other respects typical G. pulchellus. Also the fact that this "suranal" plate carries a tubercle, whereas the periproctal plates of Gymnechinus are otherwise naked, leads to the conclusion that it is not a true periproctal plate. That the gill-cuts of megaloplax are, perhaps, a little deeper than usual in Robillardi, is certainly not sufficient reason for regarding them as two distinct species (it may perhaps be due to a slight exaggeration in the drawing), and likewise I cannot lay much stress on Clark's failing to find any spicules in his specimen of megaloplax (- if really lacking, it may conceivably be due to preservation, and, in any case, the spicules of Robillardi may vary considerably in number -). Clark himself also suggests that, if the characters of his megaloplax prove to be not constant, it should be regarded only as a synonym of Robillardi. The specimen identified by Koehler as G. megaloplax in no way supports the idea of megaloplax being a distinct species; I fail, e. g., to see how his PI. XVII. 16 of "megaloplax" could be distinguished from his PI. XVII. 15 of his G. pallidus, the apical system being almost exactly alike in both. [details]
Kroh, A.; Mooi, R. (2021). World Echinoidea Database. Gymnechinus megaloplax H.L. Clark, 1912. Accessed at: http://www.marinespecies.org/echinoidea/aphia.php?p=taxdetails&id=762369 on 2024-04-26
Date action by
original description
Clark, H. L. (1912). Hawaiian and other Pacific Echini. The Pedinidae, Phymosomatidae, Stomopneustidae, and Echinometridae. <em>Memoirs of the Museum of Comparative Zoölogy at Harvard College.</em> 34/4: 205-383., available online at https://www.biodiversitylibrary.org/page/1325954
page(s): 287-288; pl. 102: figs 2-3 [details] status source Mortensen, T. (1943). A Monograph of the Echinoidea. III, 2. Camarodonta. I. Orthopsidæ, Glyphocyphidæ, Temnopleuridæ and Toxopneustidæ. vii+553 pp., C. A. Reitzel, Copenhagen. page(s): 427 [details]  Present Inaccurate Introduced: alien Containing type locality
Holotype MCZ 1291, geounit Persian Gulf [details]
From editor or global species database
Status Further, there can be no doubt that the Gymnech. megaloplax of H. L. Clark is only a synonym of G. Robillardi. The main character of this species is the large "suranal" plate (Fig. 265). But it is fairly certain that it is merely an anomalous subdivision of the genital plates which has occurred in this specimen. Exactly the same anomaly may be found in G. pulchellus, cf. fig. 268, a; p. 428, such specimens being in all other respects typical G. pulchellus. Also the fact that this "suranal" plate carries a tubercle, whereas the periproctal plates of Gymnechinus are otherwise naked, leads to the conclusion that it is not a true periproctal plate. That the gill-cuts of megaloplax are, perhaps, a little deeper than usual in Robillardi, is certainly not sufficient reason for regarding them as two distinct species (it may perhaps be due to a slight exaggeration in the drawing), and likewise I cannot lay much stress on Clark's failing to find any spicules in his specimen of megaloplax (- if really lacking, it may conceivably be due to preservation, and, in any case, the spicules of Robillardi may vary considerably in number -). Clark himself also suggests that, if the characters of his megaloplax prove to be not constant, it should be regarded only as a synonym of Robillardi. The specimen identified by Koehler as G. megaloplax in no way supports the idea of megaloplax being a distinct species; I fail, e. g., to see how his PI. XVII. 16 of "megaloplax" could be distinguished from his PI. XVII. 15 of his G. pallidus, the apical system being almost exactly alike in both. [details]
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