An endemic species flock of Cypridopsinae (Crustacea, Ostracoda) from the ancient Lake Malawi (Africa), with the description of a new genus and three new species

Abstract

We describe Malawidopsis gen. nov., a new genus of Cypridopsinae Kaufmann, 1900 from the African ancient Lake Malawi. The genus comprises at least 17 new species, which makes it a significant ostracod radiation in this lake, parallel to a similar (but independent) cypridopsine radiation in Lake Tanganyika. Three of these new species are here described: Malawidopsis stellae gen. et. sp. nov., the type species of the new genus; M. ruwaydae gen. et. sp. nov. and M. antoniae gen. et. sp. nov.. The other new species are briefly illustrated and described, but are left in open nomenclature (sp. A, B, C, etc.). Cypridopsis cunningtoni Sars, 1910 and Potamocypris fuelleborni Daday, 1910 are transferred to Malawidopsis gen. nov. and are identical to Malawidopsis spec. F and Malawidopsis spec. N, respectively.
 The new tribe Plesiocyprisopsini trib. nov. is erected, and comprises the cypridopsine genera previously in the Cypridopsini s.l. with the right valve overlapping the left valve, at least anteriorly.
 Potential drivers of speciation within this endemic clade in Lake Malawi are briefly discussed. Bathymetry might have been important, with most species being restricted to shallower depths and only four species also occurring at depths of 75 m or more, but very few specimens were retrieved from greater depths. Most species occurred on coarse sand, but this sediment category coincides with shallower stations. Overall, most species appear to have a wide geographical distribution in the lake, so no geographical parapatric speciation is apparent. The occurrence of all species in sexual populations and the significant differences in the male sexual organs and the valves suggest that sexual selection might have been the most important driver in the speciation process of this species flock, but this should be further explored. Following deep coring results in Lake Malawi, the present clade could be (at least) c one million years old.

A New Species of the Genus <i>Sarscypridopsis</i> (Crustacea: Ostracoda) Discovered in a Japanese Rice Field

“…Order Podocopida Sars, 1866 Suborder Cypridocopina Baird, 1845 Superfamily Cypridoidea Baird, 1845 Family Cyprididae Baird, 1845 Subfamily Cypridopsinae Kaufmann, 1900 Tribe Plesiocypridopsini Jacobs and Martens, 2022 Genus Sarscypridopsis McKenzie, 1977 Sarscypridopsis denticulata Smith and Ozawa, Etymology. From the Latin denticulatus meaning with small teeth, and referring to the marginal denticles along the antero-ventral and postero-ventral margins of the left valve.…”

Revision of the taxonomic position ofPseudocyprettaKlie, 1932 (Ostracoda: Cyprididae), with a redescription ofP. maculataKlie, 1932

“…REVISION OF TAXONOMIC POSITION OF PSEUDOCYPRETTA • 11 cypridopsine genera have been recorded worldwide (Meisch et al, 2019;Almeida et al, 2021;Jacobs & Martens, 2022). Seventeen of these genera do not have subapical setae: Klieopsis Martens et al, 1991(see Martens et al, 1991, Plesiocypridopsis Rome, 1965, Sarscypridopsis McKenzie, 1977(see Meisch, 2000, Potamocypris (see Martens, 1982;Horne & Smith, 2004), Pseudocypridopsis Karanovic, 1999(see Karanovic, 1999, Siamopsis Savatenalinton, 2017(see Savatenalinton, 2017, Tanganyikacypridopsis Martens, 1985(see Martens, 1985, Brazilodopsis Almeida, Higuti, Ferreira & Martens, 2021, Parananopsis Almeida, Higuti, Ferreira & Martens, 2021(see Almeida et al, 2021, Malawidopsis Jacobs & Martens, 2022 (see Jacobs & Martens, 2022); no information on these setae has been reported in six genera: e.g., Austrocypridopsis McKenzie, 1982, Cavernocypris Hartmann, 1964, Tungucypridopsis Victor, 1983. The absence of subapical setae thus seems to be a common feature of the T1 protopodite of Cypridopsinae and could be regarded as a synapomorphy for the subfamily.…”