Taxonomy

In the original publication [...]

The family Grapsidae is composed of 39 species belonging to seven genera. Currently, larval data are known for 24 out of the 39 species, but the megalopa stage remains unknown for the genera Goniopsis, Grapsus, Leptograpsus, and Planes, although megalopae collected in the plankton have been tentatively attributed to Grapsus and Planes. Thanks to the MALASPINA and MAF research projects, a significant number of megalopae were collected from open-ocean plankton worldwide, and, using DNA barcoding (16S and/or COI genes), a high percentage of them were identified. At the molecular level, Grapsidae have been widely studied, so the availability of barcode sequences in public databases has allowed us to identify the megalopa of Goniopsis pulchra, Grapsus grapsus, Leptograpsus aff. variegatus, Pachygrapsus socius, P. transversus, and Planes minutus. In the present work, these megalopae are described in detail and compared with those previously known. Consequently, for the first time, the morphology of the megalopa stage can be compared across all grapsid genera, and a set of characteristics is defined to identify the grapsid megalopa from the rest of the brachyuran megalopae.

Plant species established on the basis of early garden cultivation may have lacked the original information about their native geographical origin. Crambe suecica was originally described from its 18th-century cultivation in the Chelsea Physic Garden in London, raised from seeds without provenance that were sent from Saint Petersburg. This species has been misunderstood as native to the Baltic Sea coasts and, consequently, misinterpreted as a taxonomic synonym of C. maritima. We infer from plant morphology and the history of Russian botany that seeds of C. suecica were originally collected by Johann Christian Buxbaum in 1726 when he travelled across the Ottoman Empire and then-Russian Transcaucasia, most likely in the Gilan or Mazandaran provinces of present-day Iran. According to the morphology of its type specimen, this taxon represents a glabrous variant of C. orientalis and is hereby reduced to a synonym of the latter species. The name C. pinnatifida has been misapplied to a species native to south-eastern Europe and the north-western Caucasus. This species name is nomenclaturally superfluous and illegitimate because its protologue includes a reference to C. suecica, which is to be treated as its type-bearing synonym. This case underlines the importance of historical research in nomenclatural studies, which may be required to reach a correct taxonomic decision.