Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited

The three larval instars of Megadytes (Paramegadytes) glaucus (Brullé, 1838) and the third-instar larvae of M. (Bifurcitus) magnus Trémouilles & Bachmann, 1980 and M. (Trifurcitus) robustus (Aubé, 1838) are described and illustrated for the first time, with particular emphasis on the morphometry...

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Autor principal: Michat, M.C.
Formato: JOUR
Materias:
Chaetotaxy
Coleoptera
Dytiscidae
Larval morphology
Megadytes
Phylogeny
cladistics
larva
morphometry
phylogeny
Cybister lateralimarginalis
Cybistrini
Dytiscinae
Glaucus
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_12105759_v103_n4_p831_Michat
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_12105759_v103_n4_p831_Michat2023-10-03T16:08:58Z Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited Michat, M.C. Chaetotaxy Coleoptera Dytiscidae Larval morphology Megadytes Phylogeny cladistics larva morphometry phylogeny Coleoptera Cybister lateralimarginalis Cybistrini Dytiscidae Dytiscinae Glaucus Megadytes The three larval instars of Megadytes (Paramegadytes) glaucus (Brullé, 1838) and the third-instar larvae of M. (Bifurcitus) magnus Trémouilles & Bachmann, 1980 and M. (Trifurcitus) robustus (Aubé, 1838) are described and illustrated for the first time, with particular emphasis on the morphometry and chaetotaxy. A key to the subgenera of Megadytes Sharp, 1882 is presented. In a cladistic analysis of third-instar larval characters, Megadytes is resolved as non-monophyletic; the species of Cybistrini studied, except those included in the subgenus Trifurcitus Brinck, 1945, share three synapomorphies: (i) medial projection of frontoclypeus truncate apically, with many apical setae directed forwards; (ii) lateral projections of frontoclypeus project forwards, not flattened; and (iii) median process of prementum rounded apically. The clade composed of the subgenera Megadytes s. str., Paramegadytes Trémouilles & Bachmann, 1980 and Bifurcitus Brinck, 1945 along with Cybister lateralimarginalis (De Geer, 1774) is well supported by three synapomorphies: (i) head capsule subrectangular and (ii) distal third of mandible more strongly projected inwards, (iii) with a ring of long, hair-like setae. The two species of the subgenus Paramegadytes have bilobed lateral projections on the frontoclypeus. Megadytes (M.) marginithorax (Perty, 1830) is characterized by the very narrow notches between the medial and lateral projections of frontoclypeus. No synapomorphies were discovered to group together the two species of the subgenus Bifurcitus. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_12105759_v103_n4_p831_Michat
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Chaetotaxy
Coleoptera
Dytiscidae
Larval morphology
Megadytes
Phylogeny
cladistics
larva
morphometry
phylogeny
Coleoptera
Cybister lateralimarginalis
Cybistrini
Dytiscidae
Dytiscinae
Glaucus
Megadytes
spellingShingle Chaetotaxy
Coleoptera
Dytiscidae
Larval morphology
Megadytes
Phylogeny
cladistics
larva
morphometry
phylogeny
Coleoptera
Cybister lateralimarginalis
Cybistrini
Dytiscidae
Dytiscinae
Glaucus
Megadytes
Michat, M.C.
Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited
topic_facet Chaetotaxy
Coleoptera
Dytiscidae
Larval morphology
Megadytes
Phylogeny
cladistics
larva
morphometry
phylogeny
Coleoptera
Cybister lateralimarginalis
Cybistrini
Dytiscidae
Dytiscinae
Glaucus
Megadytes
description The three larval instars of Megadytes (Paramegadytes) glaucus (Brullé, 1838) and the third-instar larvae of M. (Bifurcitus) magnus Trémouilles & Bachmann, 1980 and M. (Trifurcitus) robustus (Aubé, 1838) are described and illustrated for the first time, with particular emphasis on the morphometry and chaetotaxy. A key to the subgenera of Megadytes Sharp, 1882 is presented. In a cladistic analysis of third-instar larval characters, Megadytes is resolved as non-monophyletic; the species of Cybistrini studied, except those included in the subgenus Trifurcitus Brinck, 1945, share three synapomorphies: (i) medial projection of frontoclypeus truncate apically, with many apical setae directed forwards; (ii) lateral projections of frontoclypeus project forwards, not flattened; and (iii) median process of prementum rounded apically. The clade composed of the subgenera Megadytes s. str., Paramegadytes Trémouilles & Bachmann, 1980 and Bifurcitus Brinck, 1945 along with Cybister lateralimarginalis (De Geer, 1774) is well supported by three synapomorphies: (i) head capsule subrectangular and (ii) distal third of mandible more strongly projected inwards, (iii) with a ring of long, hair-like setae. The two species of the subgenus Paramegadytes have bilobed lateral projections on the frontoclypeus. Megadytes (M.) marginithorax (Perty, 1830) is characterized by the very narrow notches between the medial and lateral projections of frontoclypeus. No synapomorphies were discovered to group together the two species of the subgenus Bifurcitus.
format JOUR
author Michat, M.C.
author_facet Michat, M.C.
author_sort Michat, M.C.
title Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited
title_short Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited
title_full Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited
title_fullStr Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited
title_full_unstemmed Descriptions of larvae of Megadytes (Coleoptera: Dytiscidae: Dytiscinae): The hypothesis of monophyletic origin revisited
title_sort descriptions of larvae of megadytes (coleoptera: dytiscidae: dytiscinae): the hypothesis of monophyletic origin revisited
url http://hdl.handle.net/20.500.12110/paper_12105759_v103_n4_p831_Michat
work_keys_str_mv AT michatmc descriptionsoflarvaeofmegadytescoleopteradytiscidaedytiscinaethehypothesisofmonophyleticoriginrevisited
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