Gemmula Weinkauff, 1875
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https://doi.org/ 10.5281/zenodo.7667122 |
persistent identifier |
https://treatment.plazi.org/id/961E878E-B435-8134-FE3B-70D8FBAFFDDA |
treatment provided by |
Felipe |
scientific name |
Gemmula Weinkauff, 1875 |
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Gemmula Weinkauff, 1875 View in CoL View at ENA
Gemmula Weinkauff, 1875: 287 View in CoL . Type species (s.d. Cossmann, 1896): Pleurotoma gemmata Reeve, 1843 View in CoL
(non Conrad, 1835) [= Gemmula hindsiana Berry, 1958 View in CoL ].
? Unedogemmula MacNeil, 1960: 101 View in CoL . Type species (o.d.): Turris View in CoL [= Pleurotoma View in CoL ] unedo Kiener, 1840 View in CoL .
Remarks: The new species described here shows closest resemblance to the type species of the taxon Unedogemmula MacNeil, 1860 , namely Pleurotoma unedo Kiener, 1840 . Powell (1964: 269, 1966: 48) treated Unedogemmula as a subgenus of Gemmula Weinkauff, 1875 , but acknowledged equal similarity to Lophiotoma Casey, 1904 . Medinskaya (2002) described the radula and foregut anatomy of the type species of Lophiotoma and several species of Gemmula , and evidently found no major differences. In Unedogemmula , peripheral gemmules are typically present only on the early whorls, but in Gemmula alwyni , which otherwise closely resembles G. unedo —it was misidentified as that by Medinskaya (2002) —they continue onto the later teleoconch whorls. Obsolescence of gemmules with growth would appear to be the end of a transformation sequence, and cannot be usefully utilised to qualify taxa or subtaxa. The presence of gemmules is in itself not a valid synapomorphy, as this characterises not only Gemmula , but a range of turrine and crassispirine genera.Although the type species of Unedogemmula shows a form typical of Lophiotoma , namely fusiform with a long siphonal canal and strongly shouldered or angular whorls, apparent intermediate states occur within Gemmula . On the other hand, in Turris invicta Melvill, 1910 , the juvenile gemmules may be so weak that the species could more appropriately be referred to Lophiotoma than to Gemmula . Radula characters (Powell 1966; Kilburn 1963;
Medinskaya 2002) in Gemmula , Unedogemmula , and Lophiotoma do not provide significant systematic data. Consequently, Unedogemmula is here tentatively synonymised with Gemmula .
The following couplets may be inserted into the dichotomous key to South African Gemmula species given by Kilburn (1983: 566):
1. Subsutural cord subequal in width to shoulder sulcus or wider than it; peripheral cord normally marked with brown or yellow ....................................................... 2 – Subsutural cord distinctly narrower than shoulder sulcus; peripheral cord occasionally patterned ............................................................. 3a (after couplet 3)
3a. Peripheral cord markedly angular, strongly spotted with brown ....... alwyni sp. n. – Peripheral cord neither strongly angular nor spotted with brown ........................ 4
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Gemmula Weinkauff, 1875
Kilburn, Richard N. 2005 |
Unedogemmula
MACNEIL, F. S. 1960: 101 |
Gemmula
WEINKAUFF, H. C. 1875: 287 |