The same (male) specimen as that of the fist page, in a swimming position. The palps are large, longer than half the body length according to Piersig (1897), Viets (1936) and Gerecke e.a. (2016). The specific epithet longipalpis is of course given for this reason, but I find the difference with other species, e.g. P coccinea, not very striking (in contrary to the dark colour of legs and palps and their strong physique). You can read more about the name at the end of the page. The third and fourth pair of legs have swimming hairs. The end segment of the third legs (III-P-6) has a curved shape, which is typical for Piona species and has a function in the transfer of sperm to the female. Also visible is the depression on segment IV-P-4 of the last legs, the male can hold the legs of the female in them when mating.
"What's in a name":
Piersig (1897) wrote in his book on page 104 on Curvipes longipalpis:
Bruzelins, der Entdecker dieser prachtvollen Milbe, identifizierte dieselbe irrtümlicher weise mit Nesaea coccinea Koch die, wie schon Koenike nachgewiesen, nichts anderes ist als eine Farbenvarietät von Nesaea nodata Müller.
Loosely translated:Bruzelius, the discoverer of this wonderful mite, mistakenly identified it as Neseae coccinea Koch, which, as Koenike already has proven, is nothing but a colour variety of Neseae nodata Müller.
(Piersig writes: Bruzelins, but that will be a typo). So Bruzelius erroneously identified the mite as being Neseae coccinea, which we now know as Piona coccinea. But it is not correct that this last one is a colour variety of Nesseae (Piona) nodata. It seems P. coccinea is rather variable, making it a difficult species for systematics. Piersig also gives a number of Nesaea coccinea entries as being synonyms: Neuman 1880, Haller 1882, Barrois & Moniez 1887 and Koenike 1881, 1882. He also givers Krendowskys entry Nesaea longipalpis as from an article from Charkow 1884: "Die Süsswassermilben Südrusslands , Travaux de la Soc. des Naturalistes à l'Univ. Imp. de Kharkow. 18. Bd., S. 291, Taf. VII, Fig. 2." - I have not found that article yet.
Piersig used the name Curvipes for a number of Piona species. He wasn't the only one, although the genus name Piona was already introduced in 1842 by Carl Ludwig Koch, while Curvipes was not earlier introduced than in 1891, by Koenike. But at that time it seemed a justified classification (in the same way I adapt the species names on my website to the latest changes too, for example Thyas to Parathyas). On GBIF I found the name Curvipes longipalpis as a basionym (meaning: original name). But in Gerecke e.a. (2016) I found as original name: Nesaea longipalpis Krendowskij 1878, with an indication to the mentioned article from Charkow. Later the Curvipes group was moved into (synonymized with) the Piona genus, I don't know when and by whom. But so, be it from Nesaea or from Curvipes the name became Piona longipalpis (Krendowskij 1878), with the name of the author between parentheses, according to the rules - because of that change.
Harvey (1998) gives a short list of a number of some no longer used names within the Piona genus and there replacements. He mentions Neseae Koch 1836 as a younger homonym for both Neseae Leach 1841 and Neseae Risso 1826, so these were older names, for Crustaceans and Molluscs respectively. More names in the list: Curvipes Koenike 1891 as a replacement for Neseae Koch 1836 and a few subgeneric names of Viets and Besseling, like Tetrapiona and Carneopiona. All in all it is yet another example of the problems in systematics and taxonomy...
The meaning of a few names: Neseae: old Greek, something like: "'the dweller on islands'" (Wikipedia). She was one of the Nereids, sea nymphs. Curvipes, "curved foot or leg", after the curved end segments of the males third legs.
Bibliography:
Harvey, M.S. (1998) The Australian Water Mites: A Guide to Families and Genera
CSIRO PUBLISHING (January 1, 1998), I read it from:
https://books.google.nl/books?id=rSsS1fzgtOwC&pg=PT145&lpg=PT145&dq=nesaea+risso+1826&source=bl&ots=LMsVQPQsdR&sig=ACfU3U1V0CujUWGUGGDCRbrWO5CqKxIvNA
&hl=nl&sa=X&ved=2ahUKEwjbmcnd06n3AhVEsaQKHd4kAEwQ6AF6BAgcEAM
Piona longipalpis (Krendowski, 1878) in GBIF Secretariat (2021). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2022-04-27.
Curvipes Koenike, 1891 in GBIF Secretariat (2021). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2022-04-27
More in the BIBLIOGRAPHY watermites.