Larval morphology ofAllodessusGuignot (Coleoptera: Dytiscidae)

Abstract

The three larval instars of the type species of the bidessine genus Allodessus Guignot (A. bistrigatus (Clark)) are described and illustrated for the first time including detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. Larvae of this genus are characterised by the absence of the primary pore ABc, which is a synapomorphy of the tribe Bidessini, and the presence of secondary setae on the urogomphi, which suggest a close phylogenetic relationship with Amarodytes Re´gimbart. Allodessus larvae are further characterised by a short last abdominal segment, long urogomphi, absence of colour pattern on the body, presence of a ventroapical spinula on the third antennomere, presence of pore PAk, presence of posterior secondary setae on coxa, presence of a large number of secondary setae on coxa, presence of posteroventral secondary setae on tarsus, and presence of a total of 6-7 (instar II) and 7-11 (instar III) secondary setae on metatarsus. This combination of characters separates larvae of Allodessus from those of the other known Bidessini genera.

Larval Morphology ofYolaGozis, 1886 (Coleoptera: Dytiscidae: Bidessini) and Comparison with other Genera of the Tribe Bidessini

“…In part because of this, and also to develop a system useful for phylogenetic analysis, a new descriptive template including a system of nomenclature for larval chaetotaxy was devised Alarie 1991;. So far, such descriptive framework was particularly useful in studying 11 genera: Glareadessus Wewalka and Biström, 1998 (Alarie andWewalka 2001), Amarodytes Régimbart, 1900 (Michat and Alarie 2006), Anodocheilus Babington, 1841 (Michat and Torres 2006), Liodessus Guignot, 1939), Hypodessus Guignot, 1939(Michat and Alarie 2008), Neobidessodes Hendrich and Balke, 2009and Hydroglyphus Motschulsky, 1853(Michat et al 2010), Allodessus Guignot, 1953(Michat et al 2011), Limbodessus Guignot, 1939(Michat et al 2012), Brachyvatus Zimmermann, 1919(Michat and Torres 2013, and Yola (this paper). In the following, we summarize the characters potentially useful to separate larvae of Yola from those of other bidessine genera (Table 3).…”

“…Therefore, morphometric and chaetotaxic analyses allow the exploration of additional characters potentially useful for diagnosis of genera and species. In this contribution, we pro-vide, for the first time, a detailed description of the second and third instars of a species of Yola (Yola wraniki Wewalka, 2004) in the context of modern descriptions of larvae of this tribe, which incorporate detailed morphometric and chaetotaxic analyses (e.g., Alarie 2006, 2008;Torres 2006, 2013;Michat et al 2010Michat et al , 2011Michat et al , 2012. We also compare the larval features of Yola with those of other Bidessini genera for which the larvae have been described and present a preliminary key to separate the larvae of Bidessini genera which are known in detail.…”

Larvae of Huxelhydrus syntheticus Sharp, 1882 (Coleoptera: Dytiscidae: Bidessini)

“…The only mention in the literature is a drawing of the last abdominal segment and urogomphus in the context of a key to larvae of New Zealand diving beetles (Winterbourn et al 2006). Therefore, the recent discovery of all larval instars of Huxelhydrus syntheticus Sharp, 1882 allows us to provide, for the first time, a detailed description of this genus in the context of modern works on Bidessini larvae, which incorporate detailed morphometric and chaetotaxic analyses (Alarie & Wewalka 2001;Michat & Alarie 2006, 2008Michat & Torres 2006, 2013Michat et al 2010Michat et al , 2011Michat et al , 2012Michat et al , 2015). We also discuss the most relevant characters to separate Huxelhydrus from the other Bidessini genera for which the larvae have been described in detail.…”