TL;DR: A census of Mysidae yielded a total of twelve species plus two non-nominotypical subspecies found so far in fresh and oligohaline waters of the Mediterranean, all belonging to the subfamily Mysinae, and the biogeographical pattern points to a primary origin in the brackish Paratethys; solely the cave-dwelling T. vjetrenicensis has more ancient roots in the Tethyan Sea.
Abstract: A census of Mysidae yielded a total of twelve species plus two non-nominotypical subspecies found so far in fresh and oligohaline waters of the Mediterranean, all belonging to the subfamily Mysinae. Among the nine species in fresh-waters, three are stenoendemics, namely of a single lake ( Diamysis lacustris ), of two neighbouring river systems ( Paramysis kosswigi ) or of karstic cave waters ( Troglomysis vjetrenicensis ). Four species— T. vjetrenicensis , D. lacustris , D. fluviatilis , and Paramysis adriatica sp. nov. described in this paper—are confined to freshwater tributaries of the Adriatic Sea (NE-Mediterranean). This strengthens previous findings about the outstanding role of the Adriatic basin for the endemic diversity of freshwater Mysidae within the Mediterranean. This is possibly related to alternating marine and freshwater-terrestrial phases during the Pliocene-Pleistocene in this semi-enclosed basin. Based on current knowledge, freshwater populations of D. mesohalobia heterandra are also confined to the Adriatic basin; this taxon, however, shows many more populations in brackish waters of the E-Mediterranean and Marmora basins. Two freshwater species ( Limnomysis benedeni , Hemimysis anomala ) are wide-range invaders of Ponto-Caspian origin, with recent expansion into fresh and brackish waters of the NW-Mediterranean. A further immigrant to this part of the Mediterranean, Neomysis integer , is of NE-Atlantic origin and occurs only marginally in fresh-water. Five among the nine species found at least once in fresh-water were also reported in oligohaline conditions, mostly also at even higher salinities. A total of eight species plus two subspecies were recorded in oligohaline waters ( S = 0.5–5). Among these, only one oligohalobious stenoendemic, Diamysis hebraica , inhabits streams at the Levantine coast. In the historical biogeographical context, the current distribution of only one out of nine indigenous species in an- to oligohaline waters of the Mediterranean, namely the mainly meso- to polyhalobious Mesopodopsis slabberi , may date back to the early Pliocene flooding of the Mediterranean by Atlantic waters and to later events. For most species, the biogeographical pattern points to a primary origin in the brackish (Miocene) Paratethys; solely the cave-dwelling T. vjetrenicensis has more ancient roots in the Tethyan (Mesogeic) Sea. Both these hypotheses are supported by chorological data and mainly the mineral composition of statoliths. The statoliths are composed of CaCO 3 as the metastable crystal phase vaterite in nine species plus two subspecies considered versus the otherwise more common CaF 2 (fluorite) in only three species (or in 7 + 2 versus two Mediterranean indigenes). All 12 + 2 Mediterranean taxa are figured and described in detail, particularly regarding P. adriatica sp. nov. and the substantially redescribed T. vjetrenicensis Stammer, 1933. Supplementary descriptions are given for P. kosswigi Bacescu, 1948, D. hebraica Almeida Prado-Por, 1981, and N. integer (Leach, 1814). A key to the 14 taxa is given including additional three species of potential future invaders. The tribe Mysini Haworth, 1825, is revised by detachment of the newly defined tribe Paramysini and of the revalidated Hemimysini Czerniavsky, 1882. A key to the resulting six tribes of the subfamily Mysinae is given.
TL;DR: The blind deep-sea mysid Amblyops magnus Birstein Tchindonova, 1958 is recorded for the first time from the Mariana Trench based on an adult female specimen collected near the Challenger Deep at a depth of 6555 m.
Abstract: The blind deep-sea mysid Amblyops magnus Birstein & Tchindonova, 1958 is recorded for the first time from the Mariana Trench based on an adult female specimen collected near the Challenger Deep at a depth of 6555 m. The specimen was described, illustrated and compared with the type description as well as with the materials previously collected from the Japan Trench. The mitochondrial COI barcode was also obtained from the specimen and submitted to GenBank. This is the third discovery of this rare species and significantly extends its geographic distribution range to the low latitude hadal zone.
TL;DR: Three species of Lophogastrida and eight Mysida are documented for samples from 5161–5497 m bottom depth in the Angola Basin, and previously known latitudinal ranges are extended southward for five species, and bathymetric ranges extended beyond 5000 m for six species.
Abstract: Three species of Lophogastrida and eight Mysida are documented for samples from 5161–5497 m bottom depth in the Angola Basin. Previously known latitudinal ranges are extended southward for five species, and bathymetric ranges extended beyond 5000 m for six species. Upon revision of the subfamily Petalophthalminae (Mysidae), four species previously attributed to the genus Petalophthalmus are integrated into Ipirophthalmus gen. nov. as I. liui gen. et comb. nov., I. caribbeanus gen. et comb. nov., I. oculatus gen. et comb. nov., and I. macrops gen. et comb. nov., mainly based on the structure of eyes and presence of setae on the telson. Petalophthalmus cristatus sp. nov. is described based on its reduced cornea and the structure of eyestalks, rostrum, mandibles, and telson. The structure of mouthparts, foregut and maxillipeds suggests an omnivorous mode of life. The diagnosis of the tribe Calyptommini (Mysidae: Erythropinae) is widened to cover the 3-segmented, uniramous fourth male pleopod and the non-incised eyeplate with horn-like rudiments of eyestalks in Abyssomysis cornuta gen. et sp. nov. The structure of mandibles, foregut, and second maxilliped suggest detritus feeding in this species. Keys to the Calyptommini and Petalophthalminae are given.
TL;DR: Effects of toxic chemicals on estuarine and marine crustaceans are often evaluated using the mysid Mysidopsis bahia, and pyrethroid toxicities to mysids and postlarval pink shrimp were similar, organophosphate toxicities were within a factor of 2.6 for both species, andMysids were 3 to 26 times more sensitive to the metals than were larval pinkrimp.
Abstract: Effects of toxic chemicals on estuarine and marine crustaceans are often evaluated using the mysid Mysidopsis bahia. In a literature survey of results of acute toxicity tests with estuarine crustaceans, Mysidae and Penaeidae were generally the two most sensitive families. However, neither family was consistently more sensitive (higher LC50 divided by lower LC50 > 2). Mysids were 54 times more sensitive to pyrethroids than were penaeids (N = 3 studies). Yet penaeids were 36 times more sensitive (N = 4 studies) to organochlorines and 5 times more sensitive (N = 17 studies) to organophosphates than were mysids.
Acute exposures of ≤24-h-old mysids and second postlarval pink shrimp Penaeus duorarum were conducted to compare responses of these crustaceans to each other, and to values from the literature for other estuarine crustaceans. The test compounds were chloride salts of cadmium, copper, and zinc; the organophosphates diazinon, fenthion, and malathion; and several pyrethroids – cypermethrin, fenvalerate, and permethrin.
Results showed that pyrethroid toxicities to mysids and postlarval pink shrimp were similar, organophosphate toxicities were within a factor of 2.6 for both species, and mysids were 3 to 26 times more sensitive to the metals than were larval pink shrimp.
TL;DR: The patterns of mineral composition of static bodies in the Mysidae reflect both anatomical and ecophysiological differences and with respect to population numbers in the different aquatic biota, vaterite prevails in freshwater species and fluorite is dominant among species in all brackish to marine environments.
Abstract: We studied the mineral composition of statoliths in 154 species belonging to 55 genera of Mysidae. Fluorite (CaF2) was found in 86% of Recent species, vaterite (CaCO3) in 9%, and no crystalline component in 5%. Seven samples of fossil statoliths from Upper Miocene deposits were exclusively calcite (CaCO3). Vaterite has the peak of occurrence in fresh water, fluorite in the photic zone of marine waters, and organic statoliths in oceanic deep waters. With respect to population numbers in the different aquatic biota, vaterite prevails in freshwater species and fluorite is dominant among species in all brackish to marine environments. The occurrence of CaCO3 in fresh to brackish waters coincides with fossil records and biogeographical observations. The Ponto-Caspian region is the center of abundance for Recent CaCO3-precipitating species. The rich brackish to freshwater fauna in this region probably has its roots in the brackish Paratethys, where a rich fossil material of calcareous mysid statoliths is known from Upper Miocene sediments. Morphological and scarce palaeontological evidence suggests that the earliest (Carboniferous to Jurassic) Mysidacea were mainly oceanic shrimps without statocysts; these were followed by (bentho) pelagic animals with nonmineralic organic statoliths. With the colonization of coastal to littoral areas by benthopelagic to benthic forms, mineralic statoliths were formed by precipitation of fluorite. Among the modern Mysidae, a special development occurred (in the Miocene) in the Ponto-Caspian region where CaCO3 statoliths appeared in brackish to freshwater forms. As in vertebrates, the patterns of mineral composition of static bodies in the Mysidae reflect both anatomical and ecophysiological differences.