The plankton communities from peat bog pools: structure, temporal variation and environmental factors

This is the first characterization of the structure and temporal variation of the plankton communities comprising the complete food web in five peat bog pools related to environmental factors over two consecutive ice-free periods in Tierra del Fuego (548S). Remarkably, picophytoplankton was composed solely of eukaryotic cells, surpassing the dominance expectations for these acidic water bodies, whereas testaceans were virtually absent, even as tychoplankters. Abundances of the different planktonic communities were slightly higher than those reported for Northern Hemisphere peat bogs and humic lakes. Mixotrophic nutrition prevailed among nano- and microphytoplankters, a strategy also common in humic lakes. The structures in spring of the planktonic communities were similar. In contrast, in late summer there were differences in the abundance and biomass of the different trophic compartments among small, shallow water bodies and large ones. These seem to be dictated by distinct pool size-driven patterns of water temperature variation. A general shift in the control of heterotrophic flagellates abundance in the pools occurred, changing from bottom-up regulation in spring to top-down control in late summer related to temperature-dependant variations in zooplankton abundance and composition. We hypothesize that changes in the trophic interactions affecting the entire food web occur over the open water period in these aquatic ecosystems, and that these are dictated by pool morphometry and related abiotic features.Facultad de Ciencias Naturales y MuseoInstituto de Limnología "Dr. Raul A. Ringuelet

The plankton communities from peat bog pools: structure, temporal variation and environmental factors

This is the first characterization of the structure and temporal variation of the plankton communities comprising the complete food web in five peat bog pools related to environmental factors over two consecutive ice-free periods in Tierra del Fuego (548S). Remarkably, picophytoplankton was composed solely of eukaryotic cells, surpassing the dominance expectations for these acidic water bodies, whereas testaceans were virtually absent, even as tychoplankters. Abundances of the different planktonic communities were slightly higher than those reported for Northern Hemisphere peat bogs and humic lakes. Mixotrophic nutrition prevailed among nano- and microphytoplankters, a strategy also common in humic lakes. The structures in spring of the planktonic communities were similar. In contrast, in late summer there were differences in the abundance and biomass of the different trophic compartments among small, shallow water bodies and large ones. These seem to be dictated by distinct pool size-driven patterns of water temperature variation. A general shift in the control of heterotrophic flagellates abundance in the pools occurred, changing from bottom-up regulation in spring to top-down control in late summer related to temperature-dependant variations in zooplankton abundance and composition. We hypothesize that changes in the trophic interactions affecting the entire food web occur over the open water period in these aquatic ecosystems, and that these are dictated by pool morphometry and related abiotic features.Facultad de Ciencias Naturales y MuseoInstituto de Limnología "Dr. Raul A. Ringuelet

The Hyalella (Crustacea: Amphipoda) species cloud of the ancient Lake Titicaca originated from multiple colonizations

The final publication is available at Elsevier via https://doi.org/10.1016/j.ympev.2018.03.004. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Ancient lakes are renowned for their exceptional diversity of endemic species. As model systems for the study of sympatric speciation, it is necessary to understand whether a given hypothesized species flock is of monophyletic or polyphyletic origin. Here, we present the first molecular characterization of the Hyalella (Crustacea: Amphipoda) species complex of Lake Titicaca, using COI and 28S DNA sequences, including samples from the connected Small and Large Lakes that comprise Lake Titicaca as well as from a broader survey of southern South American sites. At least five evolutionarily distant lineages are present within Lake Titicaca, which were estimated to have diverged from one another 12–20 MYA. These major lineages are dispersed throughout the broader South American Hyalella phylogeny, with each lineage representing at least one independent colonization of the lake. Moreover, complex genetic relationships are revealed between Lake Titicaca individuals and those from surrounding water bodies, which may be explained by repeated dispersal into and out of the lake, combined with parallel intralacustrine diversification within two separate clades. Although further work in deeper waters will be required to determine the number of species present and modes of diversification, our results strongly indicate that this amphipod species cloud is polyphyletic with a complex geographic history.Natural Sciences and Engineering Research Council || Discovery Grant 2012-327509Natural Sciences and Engineering Research Council || Discovery Grant 386591-2010Natural Sciences and Engineering Research Council || Undergraduate Student Research AwardsNatural Sciences and Engineering Research Council || Postdoctoral FellowshipCatholic University of Temuco, Research Direction || Limnology Project DGI-DCA 2007-01, Project MECESUP UCT 080

The Argentinean species of the genus Boeckella (Copepoda, Calanoida, Centropagidae) and related taxa

En la presente tesis se realizan sustanciales aportes al conocimiento sistemático de lacopepodofauna planctónica de aguas interiores de la Argentina, en particular de la Familia Centropagidae, perteneciente al Orden Calanoida. Esta familia abarcaespecies tanto marinas, como estuariales y de ambientes estrictamente interiores,tanto de agua dulce como salinos. De todos los miembros de la familia Centropagidaeque han logrado colonizar las aguas continentales el género Boeckella es por lejos elque ha tenido más éxito, ya sea que lo midamos en diversidad específica, en amplitudgeográfica o en abundancia. Bayly(1992a) hizo una revisión de las especiessudamericanas de Boeckella, que es aquí ampliada con la redescripción de Boeckellagibbosa (Brehm 1935) y la descripción de B. diamantina Menu-Marque y Zúñiga, 1994y B. antiqua Menu-Marque y Balseiro, 2000. La clave de determinación de lasespecies sudamericanas de Boeckella, elaborada por dicho autor sobre la base de lasquintas patas de los machos, es modificada para incluir las mencionadas especies. Seconsidera a B. titicacae (Harding, 1955) como sinónimo de B. gracilipes Daday, 1901,siguiendo el criterio de Villalobos y Zúñiga (1991). Se provee un panorama actualizado de la distribuciónde las especies de Boeckella enla Argentina, agregándose 220 nuevas citas a las que ya figuraban en la literatura. Sepresentan mapas de distribuciónde cada una de las 17 especies identificadas en la Argentina hasta el presente. Aun con la inclusión de las especies recientementehalladas y la gran cantidad de localidades citadas para especies de Boeckella desde lapublicación del clásico trabajo de Ringuelet (1958), se mantiene para la Argentinacontinental el esquema general de distribución fundamentalmente andino-patagónica "con desborde marginal por el este en el sur de la subregión vecina (en Argentina y Uruguay)" que describiera el mencionado autor. Si bien es necesario recabar másdatos sobre las localidades de Boeckella en los otros países de América del Sur, esprobable que su distribución ayude a reforzar la idea de la subregión Andina propuestasobre la base de otros taxa de artrópodos por Morrone (1996) o, más aún, su recientepropuesta de elevarla a la categoría de región biogeográfica (Morrone, 1999). Se analizan las relaciones biogeográflcas entre las especies de Boeckella de Américadel Sur utilizando un enfoque panbiogeográfico por medio de una metodología deanálisis de trazos. Para una nueva especie hallada en Tierra del Fuego, muy afín a Boeckella antiqua,pero cuyas características excepcionales en el quinto par de patas del macho laexcluyen del género Boeckella, se erige el género Karukinka, representado por Karukinka fueguina n. gen, n. sp. Los caracteres diagnósticos más sobresalientes deesta especie son referidos al quinto par de patas del macho, que en las especies delos géneros continentales Boeckella, Parabroteas, Neoboeckella, Hemiboeckella, Calamoecia, Gladioferens y en las especies marinas del género Centropages,cumplen una función estrictamente reproductiva, mientras que en el nuevo taxónconservan además función nadadora. Los rasgos más sobresalientes son la ausenciade garra en el exopodito izquierdo, la terminación de ambos exopoditos en segmentosespatulados, que del lado derecho culmina en una espina apenas curvada y, por sobretodo, la presencia de sedas nadadoras en el margen interno de ambos exopoditos. Todos éstos son considerados caracteres plesiomórficos. Se presenta una clave de identificación, basada sobre la estructura del quinto par depatas de los machos, para los géneros de Centropagidae conocidos de América del Sur. El descubrimiento de Karukinka n. gen. permite, sobre la base de un detallado estudiomorfológico, establecer comparaciones con especies del íntimamente relacionadogénero Boeckella. Se concluye que la presencia en aguas continentales deorganismos con caracteres mucho más primitivosque los de los actuales miembrosmarinos de la familia, habla a favor de la extinción del antepasado centropágido quedio origen a todos los miembros, tanto marinos como continentales de la familia. Se descartan las hipótesis de Bayly(1964) y Maly(1996) que proponen al géneromarino Centropages como el antecesor del cual derivaron todas las especies de Centropagidae que habitan aguas continentales. Se propone, en cambio, que tanto lasespecies marinas como continentales de la mencionada familia derivan de unantecesor, ya extinguido, cuyos machos poseían quintas patas con doble funciónnadadora y reproductiva. Esta hipótesis se basa sobre la morfología de la nuevaespecie hallada en un ambiente continental de agua dulce de Tierra del Fuego, Karukinka fueguina.The present thesis provides substantial knowledge on the systematics of the planktoniccopepod fauna of inland waters of Argentina, particularly of the family Centropagidae,belonging to the order Calanoida. This family includes representatives of marine, estuarine and strictly inland waters,both of freshwater and saline environments. Of all the members of the Centropagidaewhich have been able to colonize continental waters, the genus Boeckella is by far themost successful, whether we measure it by specific diversity, geographic range orabundance. Bayly (1992) published a revision of the South American species of Boeckella, which is here completed with the redescription of Boeckella gibbosa (Brehm 1935) and the detailed description of B. diamantina Menu-Marque & Zúñiga, 1994 and B. antiqua Menu-Marque & Balseiro, 2000. The identification key for the South American species of Boeckella prepared by Bayly (1992), based upon the structure ofthe male fifth legs, is here modified to include the above mentioned species. B.titicacae (Harding, 1955) is considered a junior synonym of B. gracilipes Daday, 1901,following the criterion of Villalobos & Zúñiga (1991). A complete updated list of records of the Argentinean species of Boeckella is provided,about 220 new localities are added to those previously registered from the literature. Distributional maps of the 17 species so far identified in Argentina are presented. Evenwith the inclusion of the species recently found and the large amount of new localitiescited for Boeckella species since the publication of Ringuelet's review (1958), the basicscheme for continental Argentina of an Andean-Patagonic distribution "marginallyspilling to the east on the south of the neighbouring subregion (in Argentina and Uruguay)" described by the above mentioned author still holds. Even if more data fromother South American countries are necessary, it is probable that the distribution of thespecies of Boeckella come to reinforce the idea of the Andean subregion proposed by Morrone (1996) or, still more, support his recent proposal to raise it to the category ofbiogeographical region (Morrone, 1999). The biogeographical relationships of the South American species of Boeckella areconsidered using a panbiogeographic approach based on a track analysismethodology. A new genus, Karukinka, represented by Karukinka fueguina n. gen, n. sp. is erectedto accommodate a new species very closer related to Boeckella antiqua, but whoseexceptional male fifth leg characters exclude it from the genus Boeckella. Its mostoutstanding diagnostic characters are all referred to the male fifth pair of legs, which inthe species of the continental Boeckella, Parabroteas, Neoboeckella, Hemíboeckella, Calamoecia, and Gladioferens genera and in the marine species of the genus Centropages have a strictly reproductive role, while in the new taxon they preserve aswimming function. The most important diagnostic traits are the absence of a claw inthe left exopodite, the ending of both exopodites in spatulated segments, the right ofwhich ends in a slightly curved spine which could hardly be considered a claw, andabove all, the presence of swimming setae in the inner margin of both exopodites. Allof these are considered plesiomorphic characters. A key based upon the structure of the male fifth legs is presented to identify the generaof the family Centropagidae so far known for South America. The discovery of Karukinka n. gen. permits, upon a detailed morphological study, toestablish comparisons with species of the closely related genus Boeckella. It isconcluded that the presence in inland water environments of members of the familypossessing far more primitive characters than those of their marine counterpartsspeaks in favour of the extinction of the marine ancestor which gave rise to all theextant Centropagidae, both marine and continental. The hypotheses of Bayly (1964b) and Maly(1996) which propose the marine genus Centropages as the ancestor from which all the species of Centropagidae which inhabitcontinental waters are derived, is rejected. On the contrary, it is proposed that all thespecies of this family, be them marine or continental, derive from an extinguishedancestor, whose males possessed fifth legs with both swimming and reproductivefunction. This hypothesis is based upon the morphology of Karukinka fueguina found inan ephemeral freshwater pond in Tierra del Fuego.Fil: Menu Marque, Silvina A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Halicyclops ramirezi Menu-Marque & Sorarrain, 2007, sp. nov.

Halicyclops ramirezi sp. nov. (Figs 2–28) Material examined. 3 females and 3 males from Laguna Mar Chiquita (37 ° 40´S, 57 ° 19´W) (Fig. 1). Female holotype (MACN-In 36391), male allotype (MACN-In 36392) and four dissected paratypes (MACN-In 36393), two females and two males. Description. Female. holotype total length, excluding caudal setae, 0.7 mm. Prosome: urosome ratio of holotype: 1.5. Postero-dorsal border of all prosomites smooth (Fig. 2). Genital double-somite (Fig. 3) as long as wide, with 2 large triangular protrusions located laterally in the anterior third, similar to those of H. pilosus Rocha, 1984 and small lateral integumentary windows on the posterior third. Such structures are present also in H. venezuelaensis Lindberg, 1954 (as illustrated by Rocha 1995 a), but here are slightly triangular. Seminal receptacle not visible (Fig. 3). Copulatory pore located centrally at the proximal third of the somite. Posterior edges of urosomites with denticulate hyaline membrane, larger in genital double-somite and decreasing in size in 2 subsequent urosomites, with denticles far more conspicuous on ventral than on dorsal surface (Figs 3–4). Anal pseudoperculum unarmed and with rounded margin. Anal somite deeply incised, with distal edge smooth dorsally and denticulate ventrally. Anal area with semicircular row of long spinules on each side. Caudal rami as long as wide (Fig. 3). Lateral seta inserted on a raised base located at end of slightly broader proximal third of caudal ramus, somewhat longer than or equal to the width of ramus itself. Dorsal seta with articulated base, inserted on distally-located papilla and longer than lateral seta. Outer apical seta longer and stiffer than inner apical seta. Inner median seta representing about 60 % of total body length, 2.3– 2.5 longer than outer median seta, with basal portion ornamented with sparse short setules and terminal portion with longer, more numerous setules on both sides, becoming gradually thinner towards apex. Outer median seta (Figs 5–6) also setulose, but setules shorter and not so densely packed. Antennule (Fig. 7) 6 -segmented, with the same structure and armature as other species of genus, e.g. H. venezuelaensis (as redescribed by Rocha 1995 a), H. hurlberti Rocha, 1991 and H. tetracanthus Rocha, 1995: 8, 12, 5 + spine, 6 + aesthetasc, 2, 10 + aesthetasc (Rocha 1995 a). Fourth segment about 1.8 longer than wide, its anterior margin notched at insertion of each marginal seta. Antenna (Fig. 8) 3 -segmented. Reduced coxa unarmed, fused to basis; basis with 2 plumose setae at inner distal corner; exopod represented by hyaline, sparsely plumose seta, reaching base of terminal segment. Endopod 2 -segmented; first segment bearing a single submarginal seta in distal third. Last segment bearing 5 setae along inner margin distributed 1-2 - 2 on 3 notches, and 7 setae of diverse lengths at tip; outer margin with transverse rows of spinules forming 3 archs. Mandible (Fig. 9) consisting of gnathobase provided with sharp toothed pars incisiva and reduced palp with 2 naked setae, the longest barely reaching base of teeth. FIGURES 12–21. Halicyclops ramirezi sp. nov. female. 12: maxilliped; 13: maxilliped; 14: P 1; 15: P 2; 16: P 3; 17: P 4; 18: terminal endopodal segment of P 4, whole specimen; 19: terminal endopodal segment of P 4, permanent slide; 20: P 5; 21: P 5 and P 6. Figs 13 –15, 18, 20, from paratype 1; 12, 16–17, 19, 21 from paratype 2. Scale bars: 0.1 mm. Maxillule (Fig. 10) comprising strong praecoxa and 2 -segmented palp. Distal end of praecoxa bearing 4 strong, curved, claw-like spines, 3 fused to segment and the largest articulated and bearing a stiff setule; inner surface bearing 7 conical spines of different lengths. Palp showing 4 spiny setae on proximal segment and 3 setae on distal one. Maxilla (Fig. 11) consisting of 4 segments. Praecoxa fused to coxa and bearing 2 setae ornamented with stiff setules. Naked seta present on raised swelling on coxa; single coxal endite bearing naked seta and a strong distal seta, ornamented with 3 long, stiff setules. Basis produced into strong serrate claw, ornamented with strong serrated spine and thin seta. Unsegmented endopod carrying 2 spines, thin seta and 2 short hairlike setae. Maxilliped (Figs 12–13) 2 -segmented. Basal segment armed with 2 long spiny setae, 2 spinules on opposite edge and a row of spinules distally. Apical segment armed with 5 setae, 2 of which are ornamented with conspicuous stiff setules. Swimming legs 1–4 (Figs 14–21) armature as in Table 1. P 1 (Fig. 14) basis with spine at inner corner reaching third endopodal segment and armed with very long, needle-like, stiff setules, arising in a helicoidal pattern. P 4 third endopodal segment (Figs 17–19) 1.4 longer than wide; inner apical spine 1.5 times longer than segment and on average 1.3 longer than outer apical spine: inner rim with 2 stiff, spine-like setae. Distal inner seta shorter than segment, not reaching tip of inner apical spine, almost even with external spine. P 5 (Fig. 20–21) exopod about 1.5 times longer than broad, bearing 3 spines and 1 seta. Seta slightly longer than inner spine, which is longest of the 3, almost as long as segment. Minute spinules present on external and internal margins. P 6 located on dorsal side of lateral protrusions, represented by inner seta and 2 blunt protrusions (Fig. 21). Male (Figs 22–28). Allotype (Figs 22–23) total length, excluding caudal setae, 0.53 mm. Only dimorphic traits described and illustrated. Prosome: urosome ratio of allotype about 1.7. Genital somite slightly wider than long (L/W= 0.85). Following urosomite with somewhat triangular integumentary windows in the posterior half. Inner median seta proportionally longer than in female, representing about 65 % of total body length Antennule (Fig. 24) 14 -segmented; it ends in a spatulate tip when seen in dorsal view, and presenting a complicated set of serrate spines on inner edge of joint between 12 th and 13 th segments (Fig. 25). Distal segment of P 4 endopod (Fig. 26) slightly more slender than in female, 1.5 times longer than wide; inner finely-serrate spine-like setae much longer than in female, both surpassing by far tip of external seta. Distal inner seta longer than segment. P 5 (Figs 27–28) with same armature distribution as female; tiny spinules on external margin longer and more visible. Spines much longer than in female, longest around 1.4 times longer than segment. P 6 (Fig. 28) spine reaching almost to distal edge of the segment, with a row of minute spines at base; setae finely plumose, internal longer than middle one. Etymology. The species is dedicated to Dr. Fernando César Ramírez, zooplanktologist at INIDEP (and previously at the Instituto de Biología Marina) at Mar del Plata, mentor to generations of Argentinean planktologists. Habitat. H. ramirezi sp. nov. is known only from plankton samples taken at the type locality, where it is completely outnumbered by the benthic congener H. glaber. The few collected specimens appeared in samples considered to be close to freshwater, on account of their low conductivity. More detailed sampling is needed to detect microhabitat preferences of the new species in a complex environment with fluctuating salinity levels. Differential diagnosis. Halicyclops ramirezi sp. nov. belongs to the group of species recognized by Rocha (1991) as sharing the following traits: - caudal setae bearing only setules as ornaments and these heteronomously distributed,- fourth segment of female antennule less than twice as long as wide,- inner spine of the second basipodite of P 1 reaching at least midlength of the third endopod of that swimming leg. - In addition it shares with many species of this group the spine formula 3-4 - 4 - 3 for the last exopodal segment of P 2 –P 4. The new species most closely resembles H. glaber and H. venezuelaensis. The female can be readily distinguished from the former by the presence of two slender, finely serrate spines, on the inner margin of the third endopodal segment of P 4, and from the latter by the shape of the genital double-somite, by the proportional lengths of the setae on the last endopodal segment of P 4 and on the exopod of the P 5. The male is easily distinguished from those of both species by the P 5 armature, which consists in H. ramirezi of four elements (three spines and one seta) rather than five elements (three spines and two setae).The presence of small lateral integumentary windows in the last third of the genital double-somite of the female and the second urosomite of the male is a trait shared with H. venezuelaensis, from which the new species differs by the slightly triangular shape of these structures.Published as part of Menu-Marque, Silvina & Sorarrain, Dora, 2007, The southernmost South American record of the genus Halicyclops Norman, 1903 (Cyclopoida: Cyclopidae) with the description of a new species, pp. 47-55 in Zootaxa 1607 on pages 49-54, DOI: 10.5281/zenodo.17883

The southernmost South American record of the genus Halicyclops Norman, 1903 (Cyclopoida: Cyclopidae) with the description of a new species

Menu-Marque, Silvina, Sorarrain, Dora (2007): The southernmost South American record of the genus Halicyclops Norman, 1903 (Cyclopoida: Cyclopidae) with the description of a new species. Zootaxa 1607: 47-55, DOI: 10.5281/zenodo.17883

FIGURES 22 – 28 in The southernmost South American record of the genus Halicyclops Norman, 1903 (Cyclopoida: Cyclopidae) with the description of a new species

FIGURES 22 – 28. Halicyclops ramirezi sp. nov. male. 22: habitus, dorsal; 23: urosome, lateral; 24: antennule, dorsal; 25: antennule, detail of distal segments; 26: terminal endopodal segment of P 4; 27: P 5; 28: P 5 and P 6. Figs 22 – 23, 28 from allotype; 24 – 27 from paratype 3. Scale bars: 0.1 mm

About Bullockia gen. nov., Trichomycterus mendozensis n. sp. and Revision of the Family Trichomycteridae (Pisces, Siluriformes)

A new genus of the family Trichomycteridae, Bullockia, and a new species of Trichomycterus are described. Bullockia gen. nov. is a monospecific and relict genus in the freshwaters of Chile. Trichomycterus mendozensis n. sp. is a freshwater relict from Argentina. Preliminary diagnoses of the subfamilies Pygidiinae and Nematogenyinae and the genera Trichomycterus, Hatcheria and Nematogenys are give