Tropical Amphi-Pacific and trans-Pacific disjunctions

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Cladocera of Alona affinis group from North America preserved in the collection of Professor D. G. Frey were investigated. A new subspecies of Alona ossiani Sinev, 1998 is described. Alona ossiani herricki ssp. nov. differs from the nominative subspecies in presence of 2-3 marginal denticles on postanal angle of male postabdomen, no differences between subspecies were revealed in the female morphology. An obscure taxon Alona lepida Birge,1892 was shown to be a valid species of affinis-group and is redescribed. A. lepida shares characteristic features of the group, but differs from all other species in the body shape, by postabdominal claw with basal spine almost parallel to the claw itself, and by IDL seta 1 being not claw-like. Morphology, relationships and distribution of studied taxa are discussed.

Three new species of Aloninae cladocera from Central and South Brazil are described. Two of them, Acroperus tupinamba sp. n. and Alona yara sp. n., were previously recorded from the area as European taxa Acroperus harpae (Baird, 1834) and Alona quadrangularis (O.F. Müller, 1776), respectively. Acroperus tupinamba differs from the other species of Acroperus in smaller size, long posterior setae of the valves, shorter and wider postabdomen, short setules near the base of postabdominal claw, long apical spines of antenna, and peculiar morphology of limb IV exopodite. Alona yara differs from A. quadrangularis and A. kolweizii Van Damme & Dumont, 2008 in the number of ventral setules on ventral face of limb I, from A. boliviana Sinev et Coronel, 2006 in the shape of the body and postabdomen, narrow labral keel, and absence of projections on epipodites IV–V. The third new species, Celsinotum candango sp.n. differs from all other species of the genus in proportions of postabdomen. It differs from Australian species (C. hypsophilum Frey, 1991, C parooensis Frey, 1991, and C. platamoides Frey, 1991) in a less developed dorsal keel, lateral head pores located close to midline, longer spine on basal segment of antennal exopodite, and in the presence of extremely large projections on exopodites IV–V. Celsinotum candango differs from Brazilian C. laticaudatum Smirnov & Santos-Silva, 1995 in a shorter spine on basal segment of antenna exopodite, in the shape of postabdomen and in morphology of postabdominal denticles. At present, Aloninae fauna of Brazil includes 35 species, and true diversity is undoubtedly higher, with more new species to be expected in the country.

We move the freshwater cladocerans Alona verrucosa Sars, 1901 and related species from the lump genus Alona Baird, 1843 (Anomopoda: Chydoridae: Aloninae) to Anthalona gen. n. We revise the group and describe five new taxa from tropics and subtropics: Anthalona simplex n. sp., DR Congo, A. harti n. sp., Africa (with two subspecies), A. acuta n. sp., Brazil and A. obtusa n. sp., Borneo. Anthalona is a genus of relatively small-sized, stenothermic Aloninae with specializations for scraping. Within the subfamily, the new genus is closest to Karualona and Coronatella. We discuss possible homoplasy of limb characters between latter and Anthalona. The genus can be considered an important case study in an evolutionary trend towards oligomerization of limb structures at low taxonomical levels and within an extant crustacean lineage. Composition of the genus reflects a complex history. Species with unusual morphologies (A. brandorffi, A. simplex n. sp.) appear basal in our phylogeny and may be relicts, in comparison to a pantropical A. verrucosa complex of similar forms. Several species may coexist in a single water body such as A. acuta n. sp. and A. verrucosa in the Neotropics, suggesting niche separation.

It was recently demonstrated that mountain areas add to a significant increase of the number of known cladoceran species due to higher chances of endemism. We studied six water bodies in the North Chilean Andes (XV, I and II Regions of Chile), located at more than 4000 m above sea level, and found 19 species of the Cladocera. Several selected taxa are redescribed in detail. Three new species are described: Daphnia (Ctenodaphnia) paggii sp. nov. from Salar de Lagunillas, Pleuroxus fryeri sp. nov. from Crater Lake in Licancabur Volcano (type locality) and Laguna Leija, Alona altiplana sp. nov. from Crater Lake in Licancabur Volcano (type locality) and three other water bodies. A single female, determined as Coronatella cf. circumfimbriata (Megard, 1967) from Salar de Lagunillas, probably also belongs to a yet undescribed species. Geoffreya fryeri gen. nov., sp. nov. is found in a single locality, Salar de Lagunillas. The genus Geoffreya gen. nov. (Chydoridae: Aloninae) is different from all other genera of Aloninae in a set of unique and rare characters, such as (1) exopodites III and IV, both having only four setae, all of them terminal, (2) seta 1 of exopodite V longer than setae 2–4, (3) six setae in filter plate II; (4) small size of exopodites III–V in comparison with limb I; (5) two interconnected main head pores of different size; (6) clusters of hard setules on basal and middle segments of antenna II exopodite, (7) very long setules in the lateral fascicles on the postabdomen. The postabdominal claw in Geoffreya gen. nov. bears a very short basal spine. Among 19 species found, four taxa can be regarded as cosmopolitan, ten (more than half among 19!) are Andean endemics (among them six have Patagonian congeners), two are Andean-Patagonian, one circum-Neotropical, one “Gondwanian”, one found in two very distant localities, in the Andes and high mountains of Mexico. Some zoogeographical patterns revealed in this study are discussed. Some species groups, i.e. Daphnia paggii sp. nov. and its conge-4 · Zootaxa 2430 © 2010 Magnolia Pressners, Ilyocryptus nevadensis and its congeners, are probably differentiated from some pan-continental Mesozoic taxa. We agree with previous authors that the Andean-Patagonian patterns in the cladoceran distribution likely has a Last Glacial Maximum (LGM) signature (Löffler 1984; Adamowicz et al. 2002; Mergeay et al. 2008). Based on the marked increase of number of endemic Andean taxa after our investigation of only six water bodies, we assume that the number of Neotropical endemics in the Cladocera could be significantly increased in course of further studies of the Andean high altitude waters.

The two insufficiently known South American cladoceran species, Leydigiopsis curvirostris Sars, 1901 and Leydigiopsis megalops Sars, 1901, were redescribed from the type material. Detailed morphology of the trunk limbs of these species and morphology of male L. megalops were studied for the first time. Species of the genus Leydigiopsis combine clearly plesiomorphic characters primitive morphology of head pores, male postabdomen similar to that in females, and apomorphic characters long rostrum, antennules of unusual morphology, broad postabdomen with well developed postanal denticles. Analysis of morphology suggests that Leydigiopsis belongs to the group of the small tropical genera, like Euryalona, Tretocephala, long ago separated from the main trend of Aloninae and retain numerous plesiomorphic characters.

Cladoceran communities of two lakes of Nevado de Toluca Volcano, Central Mexico, were studied. A new species of Aloninae, Alona manueli sp. nov., is described. It was previously confused with Palearctic Alona intermedia Sars, 1862, but clearly differs from it in the morphology of postabdomen, head shield and head pores, and thoracic limbs. Position of Alona manueli sp. nov. within the genus is unclear, it did not belong to any species-group within Alona s. lato. Other species recorded in the studied lakes are