On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology

Phylogenetic relationships within the diving-beetle subfamily Hydroporinae are not well understood. Some authors include the genus Pachydrus Sharp, 1882 in the tribe Hyphydrini, whereas others are in favour of excluding Pachydrus from the Hyphydrini and placing it in its own tribe, Pachydrini. Larva...

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Detalles Bibliográficos
Autores principales: Michat, M.C., Torres, P.L.M.
Formato: JOUR
Materias:
Chaetotaxy
Diving beetles
Dytiscidae
Hyphydrini
Larva
Pachydrus
Phylogeny
beetle
cladistics
larval development
morphology
morphometry
new genus
phylogeny
taxonomy
Coleoptera
Hydroporinae
Hydrovatini
Hygrobiidae
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_12105759_v105_n4_p737_Michat
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_12105759_v105_n4_p737_Michat
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spelling todo:paper_12105759_v105_n4_p737_Michat2023-10-03T16:09:00Z On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology Michat, M.C. Torres, P.L.M. Chaetotaxy Diving beetles Dytiscidae Hyphydrini Larva Pachydrus Phylogeny beetle cladistics larval development morphology morphometry new genus phylogeny taxonomy Coleoptera Dytiscidae Hydroporinae Hydrovatini Hygrobiidae Hyphydrini Pachydrus Phylogenetic relationships within the diving-beetle subfamily Hydroporinae are not well understood. Some authors include the genus Pachydrus Sharp, 1882 in the tribe Hyphydrini, whereas others are in favour of excluding Pachydrus from the Hyphydrini and placing it in its own tribe, Pachydrini. Larval characters have been underutilised in phylogenetic studies, mainly because the larvae of many taxa within the family are unknown. In this study, the phylogenetic relationships of Pachydrus are studied based on a cladistic analysis of 34 taxa and 122 morphological larval characters. For this purpose, larvae of P. obesus Sharp, 1882 are described and illustrated in detail for the first time, with particular emphasis on morphometry and chaetotaxy. First and second instars for the genus were unknown. The results support a monophyletic origin of the tribe Hyphydrini excluding Pachydrus, based on four unique character states. On the other hand, Pachydrus is resolved as the sister group of the Hydrovatini. These results suggest Pachydrus should not be placed in the Hyphydrini. Given that the Hyphydrini minus Pachydrus is a distinctive clade, based on this study, it seems useful to recognise this group as Hyphydrini. Including Pachydrus in Hyphydrini would leave the tribe with a single larval apomorphy, as most characters present in the Hyphydrini and Pachydrus are also present in the Hydrovatini. However, in the absence of larvae of Heterhydrus Fairmaire, 1869 and of a more comprehensive and inclusive analysis, we do not propose a formal exclusion of Pachydrus from Hyphydrini at this stage. Pachydrus is a highly distinctive genus within the Hydroporinae and is characterised by several larval apomorphies. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_12105759_v105_n4_p737_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
Diving beetles
Dytiscidae
Hyphydrini
Larva
Pachydrus
Phylogeny
beetle
cladistics
larval development
morphology
morphometry
new genus
phylogeny
taxonomy
Coleoptera
Dytiscidae
Hydroporinae
Hydrovatini
Hygrobiidae
Hyphydrini
Pachydrus
spellingShingle Chaetotaxy
Diving beetles
Dytiscidae
Hyphydrini
Larva
Pachydrus
Phylogeny
beetle
cladistics
larval development
morphology
morphometry
new genus
phylogeny
taxonomy
Coleoptera
Dytiscidae
Hydroporinae
Hydrovatini
Hygrobiidae
Hyphydrini
Pachydrus
Michat, M.C.
Torres, P.L.M.
On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology
topic_facet Chaetotaxy
Diving beetles
Dytiscidae
Hyphydrini
Larva
Pachydrus
Phylogeny
beetle
cladistics
larval development
morphology
morphometry
new genus
phylogeny
taxonomy
Coleoptera
Dytiscidae
Hydroporinae
Hydrovatini
Hygrobiidae
Hyphydrini
Pachydrus
description Phylogenetic relationships within the diving-beetle subfamily Hydroporinae are not well understood. Some authors include the genus Pachydrus Sharp, 1882 in the tribe Hyphydrini, whereas others are in favour of excluding Pachydrus from the Hyphydrini and placing it in its own tribe, Pachydrini. Larval characters have been underutilised in phylogenetic studies, mainly because the larvae of many taxa within the family are unknown. In this study, the phylogenetic relationships of Pachydrus are studied based on a cladistic analysis of 34 taxa and 122 morphological larval characters. For this purpose, larvae of P. obesus Sharp, 1882 are described and illustrated in detail for the first time, with particular emphasis on morphometry and chaetotaxy. First and second instars for the genus were unknown. The results support a monophyletic origin of the tribe Hyphydrini excluding Pachydrus, based on four unique character states. On the other hand, Pachydrus is resolved as the sister group of the Hydrovatini. These results suggest Pachydrus should not be placed in the Hyphydrini. Given that the Hyphydrini minus Pachydrus is a distinctive clade, based on this study, it seems useful to recognise this group as Hyphydrini. Including Pachydrus in Hyphydrini would leave the tribe with a single larval apomorphy, as most characters present in the Hyphydrini and Pachydrus are also present in the Hydrovatini. However, in the absence of larvae of Heterhydrus Fairmaire, 1869 and of a more comprehensive and inclusive analysis, we do not propose a formal exclusion of Pachydrus from Hyphydrini at this stage. Pachydrus is a highly distinctive genus within the Hydroporinae and is characterised by several larval apomorphies.
format JOUR
author Michat, M.C.
Torres, P.L.M.
author_facet Michat, M.C.
Torres, P.L.M.
author_sort Michat, M.C.
title On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology
title_short On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology
title_full On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology
title_fullStr On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology
title_full_unstemmed On the systematic position of the diving-beetle genus Pachydrus (Coleoptera: Dytiscidae: Hydroporinae): Evidence from larval chaetotaxy and morphology
title_sort on the systematic position of the diving-beetle genus pachydrus (coleoptera: dytiscidae: hydroporinae): evidence from larval chaetotaxy and morphology
url http://hdl.handle.net/20.500.12110/paper_12105759_v105_n4_p737_Michat
work_keys_str_mv AT michatmc onthesystematicpositionofthedivingbeetlegenuspachydruscoleopteradytiscidaehydroporinaeevidencefromlarvalchaetotaxyandmorphology
AT torresplm onthesystematicpositionofthedivingbeetlegenuspachydruscoleopteradytiscidaehydroporinaeevidencefromlarvalchaetotaxyandmorphology
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