Hydaticus tuyuensis Trémouilles (Coleoptera: Dytiscidae): Larval morphology and phylogenetic relationships within Dytiscinae
The three larval instars of Hydaticus (Guignotites) tuyuensis Trémouilles are described and illustrated for the first time, emphasizing the morphometry and chaetotaxy. Second- and third-instar larvae of the known species of the subgenus Guignotites Brinck are characterized by a trilobate median proc...
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2006
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00188158_v563_n1_p479_Michat http://hdl.handle.net/20.500.12110/paper_00188158_v563_n1_p479_Michat |
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| Sumario: | The three larval instars of Hydaticus (Guignotites) tuyuensis Trémouilles are described and illustrated for the first time, emphasizing the morphometry and chaetotaxy. Second- and third-instar larvae of the known species of the subgenus Guignotites Brinck are characterized by a trilobate median process of prementum. All larval instars of H. tuyuensis, however, have a bilobate process, similar to that present in the known species of the subgenus Hydaticus Leach. This implies that a trilobate process cannot be used as a diagnostic character for Guignotites. Alternatively, Guignotites as presently defined may not represent a natural group. A cladistic analysis of 57 larval characters suggests that the genus Hydaticus shares a common origin with the clade composed of the genera Eretes Laporte and Thermonectus Dejean, based on the following synapomorphies: (i) abdominal segment VII almost completely sclerotized ventrally; the absence of (ii) additional ventroapical pores on the third antennomere, (iii) setae FE4 and FE6, (iv) additional setae on the femur and (v) additional setae on the tibia; and the presence of (vi) setae on the median process of prementum and (vii) spinulae on the second labial palpomere. A bilobate or trilobate median process of the prementum and the submedial insertion of seta AN3 distinguish Hydaticus from the remaining genera of Dytiscinae studied. © Springer 2006. |
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