Phylogenetic analysis of Adephaga (Coleoptera) based on characters of the larval head

Abstract. Characters of the head of adephagan larvae were examined and analysed phylogenetically. A labrum which is completely fused to the clypeofrons and the presence of a closed prepharyngeal tube are autapomorphies of Adephaga. Partial reduction of the fossa maxillaris, cardo and stipes forming a functional unit, the immobilization of the lacinia, attachment of M. craniolacinialis to the lateral stipital wall, and loss of one stipitopalpal muscle, are considered autapomorphies of Adephaga excluding Gyrinidae. Complete reduction of the fossa maxillaris and the presence of M. craniostipitalis medialis are possible autapomorphies of Adephaga excluding Gyrinidae and Haliplidae. The presence of caudal tentorial arms, insertion of the galea on the mesal side of palpomere I, and absence of the lacinia are considered synapomorphies of Trachypachidae and Dytiscoidea (Noteridae, Amphizoidae, Hygrobiidae, Dytiscidae). The presence of a slender, elongated process of the head capsule, which articulates with a corresponding socket of the cardo, is a possible autapomorphy of Dytiscoidea. The sinuate frontal sutures, distinctly protruding prementum, shortened M. craniostipitalis medialis, and absence of M. submentopraementalis are considered autapomorphies of Geadephaga excluding Trachypachidae. The presence of a regular row of hairs along the anterior hypopharyngeal margin is a possible autapomorphy of Geadephaga excluding Trachypachidae and Rhysodidae. Improvement of the hypopharyngeal filter apparatus suggests the monophyly of Anisochaeta. Presence of a penicillum and partial reduction of the lacinia are possible autapomorphies of Anisochaeta excluding Omophronini. Larvae of Cychrini, Carabini, Nebriini and Notiophilini are characterized by a strongly developed, cone-shaped hypodon. Postocular and cervical ridges, crosswise arrangement of antennal muscles, and a completely flattened hypopharynx are considered autapomorphies of Caraboidea Limbata.     

The morphological evolution of the Adephaga (Coleoptera)

The evolution of the coleopteran suborder Adephaga is discussed based on a robust phylogenetic background. Analyses of morphological characters yield results nearly identical to recent molecular phylogenies, with the highly specialized Gyrinidae placed as sister to the remaining families, which form two large, reciprocally monophyletic subunits, the aquatic Haliplidae + Dytiscoidea (Meruidae, Noteridae, Aspidytidae, Amphizoidae, Hygrobiidae, Dytiscidae) on one hand, and the terrestrial Geadephaga (Trachypachidae + Carabidae) on the other. The ancestral habitat of Adephaga, either terrestrial or aquatic, remains ambiguous. The former option would imply two or three independent invasions of aquatic habitats, with very different structural adaptations in larvae of Gyrinidae, Haliplidae and Dytiscoidea.     

The systematic position of Meruidae (Coleoptera, Adephaga) and the phylogeny of the smaller aquatic adephagan beetle families

A phylogenetic analysis of Adephaga is presented. It is based on 148 morphological characters of adults and larvae and focussed on a placement of the recently described Meruidae, and the genus‐level phylogeny of the smaller aquatic families Gyrinidae, Haliplidae and Noteridae. We found a sister group relationship between Gyrinidae and the remaining adephagan families, as was found in previous studies using morphology. Haliplidae are either the sister group of Dytiscoidea or the sister group of a clade comprising Geadephaga and the dytiscoid families. Trachypachidae was placed as the sister group of the rhysodid‐carabid clade or of Dytiscoidea. The monophyly of Dytiscoidea including Meru is well supported. Autapomorphies are the extensive metathoracic intercoxal septum, the origin of the metafurca from this structure, the loss of Mm. furcacoxalis anterior and posterior, and possibly the presence of an elongated subcubital setal binding patch. Meruidae was placed as sister group of the Noteridae. Synapomorphies are the absence of the transverse ridge of the metaventrite, the fusion of abdominal segments III and IV, the shape of the strongly asymmetric parameres, and the enlargement of antennomeres 5, 7 and 9. The Meru‐noterid clade is the sister group of the remaining Dytiscoidea. The exact position of Aspidytes within this clade remains ambiguous: it is either the sister group of Amphizoidae or the sister group of a clade comprising this family and Hygrobiidae + Dytiscidae. The sister group relationship between Spanglerogyrinae and Gyrininae was strongly supported. The two included genera of Gyrinini form a clade, and Enhydrini are the sister group of a monophylum comprising the remaining Enhydrini and Orectochilini. A branching pattern (Peltodytes + (Brychius + Haliplus)) within Haliplidae was confirmed. Algophilus, Apteraliplus and the Haliplus‐subgenus Liaphlus form a clade. The generic status of the two former taxa is unjustified. The Phreatodytinae are the sister group of Noterinae, and Notomicrus (+ Speonoterus), Hydrocoptus, and Pronoterus branch off successively within this subfamily. The search for the larvae of Meru and a combined analysis of morphological and molecular data should have high priority. © The Willi Hennig Society 2006.     

A genus-level supertree of Adephaga (Coleoptera)

A supertree for Adephaga was reconstructed based on 43 independent source trees – including cladograms based on Hennigian and numerical cladistic analyses of morphological and molecular data – and on a backbone taxonomy. To overcome problems associated with both the size of the group and the comparative paucity of available information, our analysis was made at the genus level (requiring synonymizing taxa at different levels across the trees) and used Safe Taxonomic Reduction to remove especially poorly known species. The final supertree contained 401 genera, making it the most comprehensive phylogenetic estimate yet published for the group. Interrelationships among the families are well resolved. Gyrinidae constitute the basal sister group, Haliplidae appear as the sister taxon of Geadephaga+Dytiscoidea, Noteridae are the sister group of the remaining Dytiscoidea, Amphizoidae and Aspidytidae are sister groups, and Hygrobiidae forms a clade with Dytiscidae. Resolution within the species-rich Dytiscidae is generally high, but some relations remain unclear. Trachypachidae are the sister group of Carabidae (including Rhysodidae), in contrast to a proposed sister-group relationship between Trachypachidae and Dytiscoidea. Carabidae are only monophyletic with the inclusion of a non-monophyletic Rhysodidae, but resolution within this megadiverse group is generally low. Non-monophyly of Rhysodidae is extremely unlikely from a morphological point of view, and this group remains the greatest enigma in adephagan systematics. Despite the insights gained, our findings highlight that a combined and coordinated effort of morphologists and molecular systematists is still required to expand the phylogenetic database to enable a solid and comprehensive reconstruction of adephagan phylogeny. See also Supplementary material in the online edition at doi:10.1016/j.ode.2006.05.003     

Studies of the metathorax of the trout-stream beetle,Amphizoa lecontei Matthews (Coleoptera : Amphizoidae): Contribution towards clarification of the systematic position of Amphizoidae

Skeleton and musculature of the metathorax and the abdominal nerve cord of Amphizoa lecontei (Coleoptera : Amphizoidae) Matthews were examined and compared to those of other members of Adephaga (Coleoptera). The following characters may be important for phylogenetic analysis. The narrow prescutal area and moderately developed mesophragma with distinctly separated median phragmal lobes in Amphizoa is considered as plesiomorphic, whereas the median phragmal lobes lying closely together or fused is a possible synapomorphy of Hygrobiidae and Dytiscidae. The short 1st axillary sclerite of Amphizoa may be an autapomorphy of the group. The weakly arched notum and the poorly developed metaphragma arc obviously the result of tendency towards flightlessness. The anepisternum meets the middle coxal cavity. The prosternal process does not reach the meta “sternum” (“sternum” = preepisternum + basisternum presternum + spinasternum 2). The specialized pro-meso-meta “sternal” articulation in Hygrobia and Dytiscidae is considered a synapomorphy of both groups. The amphizoid metafurca is distinctly reduced in size. Pouch-like anterolateral excavations are considered plesiomorphic. Strong dorsolateral and weak ventrolateral projections of the metafurca may be a synapomorphy of Hygrobiidae and Dytiscidae. The hind legs of Amphizoa are not adapted for swimming, except for very sparse fringes of thin setae. Swimming hind legs are considered as a synapomorphy of Hygrobiidae and Dytiscidae. The main flight muscles were degenerated in all specimens of Amphizoa examined. Absence of muscle (M) 65 may be autapomorphic for Amphizoidae. Presence of M 72 is a symplesiomorphy of Amphizoidae and Dytiscidae. M 81 and M 83 arc absent. The strong M 82 is considered as plesiomorphic. The moderate size of M 85 is connected with the lack of swimming ability. The elongate abdominal nerve cord in Amphizoa points towards a sistergroup relationship between Hygrobiidae and Dytiscidae in both of which the abdominal nerve cord shows a high degree of fusion.The phylogenetic propositions of Baehr (1979), and Kavanaugh (1986), are not consistent with the interpretation provided herein, whereas the conclusions of Burmeister (1976), Ruhnau (1986) and Beutel (1986) seem to correlate well. Therefore, it is suggested that the Amphizoidae are the sistergroup of Hygrobiidae + Dytiscidae.     

On the phylogeny and evolution of Mesozoic and extant lineages of Adephaga (Coleoptera,Insecta)

The relationships of extant and extinct lineages of Adephaga were analysed formally for the first time. Emphasis is placed on the aquatic and semiaquatic groups and their evolution in the Mesozoic. ?Triadogyrus and ?Mesodineutus belong to Gyrinidae, the sister group of the remaining families. ?Triaplidae are the sister group of the following groups (Haliplidae, Geadephaga, Dytiscoidea incl. ?Liadytidae, ?Parahygrobiidae and ?Coptoclavidae [major part]). The lack of a ventral procoxal joint and a very short prosternal process are plesiomorphies of ?Triaplidae. ?Coptoclavidae and ?Timarchopsinae are paraphyletic. ?Timarchopsis is placed in a geadephagan clade. In contrast to other coptoclavids, its metathorax is close to the condition found in Haliplidae, with a complete transverse ridge and coxae with large plates and free mesal walls. ?Coptoclavidae s.str., i.e. excl. ?Timarchopsis, is a dytiscoid subgroup. The mesal metacoxal walls are fused, the coxal plates are reduced, and the transverse ridge is absent. ?Stygeonectes belongs to this dytiscoid coptoclavid unit and is therefore misplaced in ?Timarchopsinae. ?Liadytidae belongs to a dytiscoid subgroup, which also comprises the extant families Aspidytidae, Amphizoidae, Hygrobiidae and Dytiscidae. ?Parahygrobia is the sister group of Hygrobiidae. The larvae are characterized by a broad gula, the absence of the lacinia, retractile maxillary bases and very long urogomphi set with long setae. ?Liadytiscinae is the sister group of extant Dytiscidae. There is no support for a clade ?Eodromeinae and for Trachypachidae incl. ?Eodromeinae. ?Fortiseode is nested within Carabidae. The exclusion of fossil taxa has no effect on the branching pattern. The evolution of Adephaga in the Mesozoic is discussed. Possible reasons for the extinction of ?Coptoclavidae are the rise of teleost fish and the competition of Gyrinidae and Dytiscidae, which possess efficient defensive glands and larval mandibular sucking channels.     

The systematic position of Aspidytidae, the diversification of Dytiscoidea (Coleoptera, Adephaga) and the phylogenetic signal of third codon positions

Characters of the newly discovered larvae of the South African Cliff Water Beetle Aspidytes niobe were examined and integrated into a data matrix including all families of Dytiscoidea as well as Haliplidae. Fifty-three morphological characters of adults and larvae were analysed separately and combined with molecular data from six nuclear and mitochondrial genes. The phylogeny of the group is reconstructed for the study of the evolution of swimming behaviour and larval feeding habits, as well as the shift in diversification rates leading to the two most speciose lineages. The parsimony analysis of all equally weighted morphological and molecular characters combined resulted in a single well supported tree with the topology (Noteridae (Hygrobiidae ((Aspidytidae, Amphizoidae) Dytiscidae))), in agreement with the molecular data alone, but in contradiction to the morphological data, which favoured a topology in which Hygrobiidae is sister to Dytiscidae. The exclusion of third codon positions of the three protein coding genes resulted in a topology identical to that obtained with the morphological data alone, but the use of Bayesian probabilities or the amino acid sequence resulted in the same topology as that of the tree obtained with parsimony using all equally weighted characters. We concluded that interactions of third codon positions with the other data are complex, and their removal is not justified. There was a significant increase in the diversification rate at the base of the richest families (Noteridae and Dytiscidae), which could be associated with the development of simultaneous stroke and higher swimming performance, although data on the swimming behaviour of some basal groups of Noteridae are incomplete. The presence of larval mandibular sucking channels may have contributed to the diversification of Dytiscidae and the species-rich noterid genera Hydrocanthus and Canthydrus .     

Phylogeny of hydradephagan water beetles inferred from 18S rRNA sequences

Several families in the beetle suborder Adephaga have an aquatic life style and are commonly grouped in the "Hydradephaga," but their monophyly is contentious and relationships between and within these families are poorly understood. Here we present full-length 18S rRNA sequence for 84 species of Hydradephaga, including representatives of most major groups down to the tribal level, and a total of 68 species of the largest family, Dytiscidae. Using a direct optimization method for the alignment of length-variable regions, the preferred tree topology was obtained when the cost of gaps and the cost of nucleotide changes were equal, and three hypervariable regions of 18S rRNA were downweighted by a factor of five. Confirming recent molecular studies, the Hydradephaga were found to be monophyletic, indicating a single colonization of the aquatic medium. The most basal group within Hydradephaga is Gyrinidae, followed in a comb-like arrangement by families Haliplidae, Noteridae, Amphizoidae, and Hygrobiidae plus Dytiscidae. Under most alignment parameters, Hygrobiidae is placed amid Dytiscidae in an unstable position, suggesting a possible data artifact. Basal relationships within Dytiscidae are not well established, nor is the monophyly of subfamilies Hydroporinae and Colymbetinae. In contrast, relationships at the genus level appear generally well supported. Despite the great differences in the rates of change and the significant incongruence of the phylogenetic signal in conserved vs hypervariable regions of the 18S rRNA gene, both contribute to establish relationships at all taxonomic levels.     

基于线粒体基因组序列的鞘翅目肉食亚目水生类群系统发育分析

【目的】明确肉食亚目(Adephaga)水生类群线粒体基因组的基本特征,并基于线粒体基因组序列分析肉食亚目水生类群的系统发育关系。【方法】基于Illumina HiSeq X Ten测序技术测定了圆鞘隐盾豉甲Dineutus mellyi和齿缘龙虱Eretes sticticus的线粒体全基因组序列,对其进行了基因注释,并对其tRNA基因二级结构进行了预测分析。加上已公布的鞘翅目(Coleoptera)肉食亚目水生类群17个种的线粒体基因组序列,对该类群共19个种线粒体的蛋白质编码基因(protein-coding genes, PCGs)开展了比较基因组学分析,包括AT含量、密码子偏好性、选择压力等。基于13个PCGs的氨基酸序列和核苷酸序列,利用最大似然法(ML)和贝叶斯法(BI)分别构建鞘翅目肉食亚目水生类群的系统发育关系,并通过FcLM分析进一步评估伪龙虱科(Noteridae)和瀑甲科(Meruidae)的系统发育位置。【结果】圆鞘隐盾豉甲和齿缘龙虱的线粒体基因组全长分别为16 123 bp(GenBank登录号: MN781126)和16 196 bp(GenBank登录号: MN781132),都包含13个PCGs、22个tRNA基因、2个rRNA基因和1个D-loop区(控制区)。19个肉食亚目水生类群线粒体基因组PCGs的碱基组成都呈现A+T偏好性,在密码子使用上也都偏向于使用富含A+T的密码子;在进化过程中13个PCGs的进化模式相同,都受到纯化选择。基于线粒体基因组13个PCGs的氨基酸序列的肉食亚目水生类群的系统发育关系为(豉甲科Gyrinidae+(沼梭甲科Haliplidae+((壁甲科Aspidytidae+(两栖甲科Amphizoidae+龙虱科Dytiscidae))+(水甲科Hygrobiidae+(瀑甲科Meruidae+伪龙虱科Noteridae)))))。【结论】研究结果表明,豉甲科是肉食亚目水生类群的基部类群,接下来是沼梭甲科和龙虱总科;伪龙虱科和瀑甲科互为姐妹群,并一起作为龙虱总科内部的一个分支;两栖甲科与龙虱科具有更近的亲缘关系。     

Ultraconserved elements show utility in phylogenetic inference of Adephaga (Coleoptera) and suggest paraphyly of ‘Hydradephaga’

The beetle suborder Adephaga has been the subject of many phylogenetic reconstructions utilizing a variety of data sources and inference methods. However, no strong consensus has yet emerged on the relationships among major adephagan lineages. Ultraconserved elements (UCEs) have proved useful for inferring difficult or unresolved phylogenies at varying timescales in vertebrates, arachnids and Hymenoptera. Recently, a UCE bait set was developed for Coleoptera using polyphagan genomes and a member of the order Strepsiptera as an outgroup. Here, we examine the utility of UCEs for reconstructing the phylogeny of adephagan families, in the first in vitro application a UCE bait set in Coleoptera. Our final dataset included 305 UCE loci for 18 representatives of all adephagan families except Aspidytidae, and two polyphagan outgroups, with a total concatenated length of 83 547 bp. We inferred trees using maximum likelihood analyses of the concatenated UCE alignment and coalescent species tree methods (astral ii , ASTRID, svdquartets ). Although the coalescent species tree methods had poor resolution and weak support, concatenated analyses produced well‐resolved, highly supported trees. Hydradephaga was recovered as paraphyletic, with Gyrinidae sister to Geadephaga and all other adephagans. Haliplidae was recovered as sister to Dytiscoidea, with Hygrobiidae and Amphizoidae successive sisters to Dytiscidae. Finally, Noteridae was recovered as monophyletic and sister to Meruidae. Given the success of UCE data for resolving phylogenetic relationships within Adephaga, we suggest the potential for further resolution of relationships within Adephaga using UCEs with improved taxon sampling, and by developing Adephaga‐specific probes.     

Molecular phylogeny of the highly disjunct cliff water beetles from South Africa and China (Coleoptera: Aspidytidae)

The superfamily Dytiscoidea contains six families with an aquatic lifestyle, with most of its extant diversity in two families: the burrowing water beetles (Noteridae) and the diving beetles (Dytiscidae). The other families have few species (up to six) and generally highly disjunct extant distributions. Aspidytidae currently contains one genus with two species, one in China and one in South Africa. Here we provide the first molecular data for the Chinese species, allowing us to explore the phylogenetic relationships and position of both species of this small family for the first time. Based on a matrix of 11 genes we inferred a phylogenetic hypothesis for Dytiscoidea including all extant families. Unexpectedly, Aspidytidae were consistently recovered as paraphyletic relative to Amphizoidae, despite being well characterized by apparently synapomorphic adult features. A re‐examination of larval characters in the two aspidytid species revealed that the larva of the Chinese species is strikingly similar to that of Amphizoidae. Both share a series of plesiomorphic features but also some potential synapomorphies, including a dense vestiture of short setae on the head capsule, anteriorly shifted posterior tentorial grooves and widely separated labial palps. Arguably these features may belong to the groundplan of the clade Aspidytidae + Amphizoidae, with far‐reaching secondary modifications (including reversals) in the South African Aspidytes niobe. At present we retain the family Aspidytidae, however, due to the strong adult morphological synapomorphies of the two extant species, and the fact that the molecular paraphyly of the family may result from the highly divergent nature of the two extant species. This long evolutionary separation and strong divergence, in terms of gene sequences and larval features, is undeniable, substantial levels of saturation in third codon positions of protein‐coding genes being present between the two taxa. We address this issue taxonomically by introducing the new genus S inaspidytes gen. nov. for the Chinese Aspidytes wrasei. The continued contentious relationships amongst Dytiscidae, Hygrobiidae, Aspidytidae and Amphizoidae highlight the need for more data to address dytiscoid phylogenetics, possibly involving a genomic approach. © 2016 The Linnean Society of London     

水生肉食亚目(Hydradephaga)系统发育学研究简论

水生肉食亚目(Hydradephaga)属于鞘翅目Coleoptera,是一类具有水生习性的食肉性真正水生甲虫(True water beetles)。在真正水生甲虫的系统分类中存在三种假说,一种是肉食亚目(Adephaga)位于该系统的基部,一种是多食亚目(Polyphaga)位于该系统基部,第三种是藻食亚目(Myxophaga)位于该系统基部。最近研究结果更多倾向第一种假说。目前水生肉食亚目大约有5 500个种,200多个属,含8个科。水生肉食亚目的科间水平系统发育关系虽被广泛研究,但观点仍不统一。有代表意义的有三个假说,一是豉甲科(Gyrinidae)位于系统基部,接下来是龙虱科(Dytiscidae)、两栖甲科(Amphizoidae)、水甲科(Hygrobiidae)、小粒龙虱科(Noteridae)与沼梭科(Haliplidae);二是沼梭科位于系统的基部;三是豉甲科位于系统的基部,接下来是沼梭科和龙虱总科(Dytiscoidea),其中龙虱总科由两栖甲科、水甲科、龙虱科、小粒龙虱科组成。目前根据形态学的分类,并结合分子系统学研究方法,第三种假说更符合水生肉食亚目的系统分类,也支持了水生肉食亚目作为一个单系,其祖先来自陆生的假说。     

豉甲科及水生肉食亚目的分子系统发育学分析(昆虫纲：鞘翅目)

利用PAUP和MrBayes软件,对线粒体COⅠ基因序列3个密码子位置的数据模块分别进行了豉甲科(Gyrinidae)和水生肉食亚目(Hydradephaga)在亚科或科水平上的系统发育学分析,结果表明第二密码子数据模块获得了理想的分析结果。由PAUP生成的豉甲科最优树来自第二密码子数据模块的分析,而由MrBayes生成的最优树来自全部密码子数据模块的分析。此外,用对应的氨基酸序列生成的ME和MP树与第二密码子数据模块分析的结果也一致。亚科Orectochilinae和Gyrininae以高的支持率形成了单系。然而,来自亚科Enhydrinae的种Porrorhynchus landaisi landaisi呈现了异常的位置。SH-test检验也支持该异常位置,表明这个种可能代表了一个科。在来自第二密码子数据模块的水生肉食亚目最优ML树中,整个Hydradephaga树呈现单系,豉甲科位于树的基部,表明了该科在水生肉食亚目中是一个早期的分支。在树中还产生了一个单系的Dytiscoidea总科,由Dytiscidae、Hygrobiidae、Noteridae和Amphizoidae 4个科组成,单系的Haliplidae与之成为姐妹群。此外线粒体分子钟的结果表明豉甲科的5对相近种间的分化是一个短时期内发生的(0.01～1.81百万年前),这点可能与它们的特殊地理分布有关。     

On the thoracic anatomy of the Madagascan Heterogyrus milloti and the phylogeny of Gyrinidae (Coleoptera)

Gyrinidae is a group of beetles with a unique specialization of swimming on the water surface. Heterogyrus milloti Legros (Heterogyrinae) from Madagascar is a species with various preserved plesiomorphic features. The information on the morphology and biology was very limited until recently, and the thoracic anatomy remained largely unknown. Consequently, the aim of the present study is to describe external and internal thoracic features of Heterogyrus Legros in detail and to interprete them with respect to their phylogenetic and functional significance, with a special focus on the unusual flight apparatus of Gyrinidae. Characters documented with innovative techniques are compared to conditions found in other gyrinid genera and other groups of Adephaga, including characters of other body parts and larvae. A data matrix with 144 characters of adults, larvae and eggs was compiled and analysed cladistically. Gyrinidae excluding Spanglerogyrus Folkers (Heterogyrinae + Gyrininae) is supported by many apomorphies, mainly by a unique locomotor apparatus with paddle‐like middle and hind legs. The results confirm Heterogyrus as the earliest diverging branch in Gyrinidae except Spanglerogyrus, implying a sister‐group relationship between this genus and Gyrininae, a clade comprising Gyrinini, Dineutini and Orectochilini. The presence of an opening between the mesanepisternum and elytra, reduction of the lateral metafurcal arms, loss of the metathoracic M. furcacoxalis lateralis, and modifications of the head, including the dorsal shift of the upper subcomponent of the compound eyes, are synapomorphies of the three tribes. The monophyly of Gyrinini is moderately well‐supported, whereas Orectochilini is strongly supported by different characters including a highly simplified but functioning flight apparatus. A clade comprising Orectochilini and the dineutine genera is suggested by synapomorphies of adults and larvae. The monophyly of Dineutini was supported in a recent study, but not by the characters analysed here. Features of adults, larvae and eggs indicate that Gyrinidae are the sister group to the remaining adephagan families, as suggested in some earlier morphology‐based studies and recent analyses of large molecular datasets.     

A preliminary study on the phylogenetic relationships of Copelatus Erichson (Coleoptera: Dytiscidae: Copelatinae) based on larval chaetotaxy and morphology

The phylogenetic relationships of the diving-beetle (Dytiscidae) subfamily Copelatinae are not well known. Some authors postulated a sister-group relationship between Copelatus Erichson and the remaining Dytiscidae, relying mainly on the absence of a mandibular channel in Copelatus. Other authors suggested a more derived position of the genus. Larval characters have been underutilized in phylogenetic studies, mainly because the larvae of many taxa within the family and, in particular, within Copelatinae are unknown. A comprehensive approach aimed to study the phylogenetic placement of a member of this subfamily based on larval characters has not been produced so far. In this study, the phylogenetic relationships of Copelatus are explored based on a cladistic analysis of 24 taxa and 120 chaetotaxic and morphological characters from larvae. For this purpose, larvae of Copelatus longicornis Sharp are described and illustrated in detail for the first time, with particular emphasis on morphometry and chaetotaxy, with the latter being unexplored until now. The results support a derived position of Copelatus within Dytiscidae, with a sister-group relationship between this genus and a clade formed by the subfamilies Lancetinae, Coptotominae, Laccophilinae, Colymbetinae, Matinae, and Dytiscinae, and part of Agabinae. No evidence was found for a sister-group relationship between Copelatus and the remaining Dytiscidae so that the absence of a mandibular channel in this genus is likely a reduction. Copelatus is supported by three apomorphies within Dytiscidae: mandibular channel absent, internal margin of the stipes with three robust spinulae, and seta MX8 inserted subapically on the galea. Handling editor: K. Martens     

The phylogeny of diving beetles (Coleoptera: Dytiscidae) and the evolution of sexual conflict

A model of evolution based on conflicts of interest between the sexes over mating decisions is examined in relation to diving beetles (Dytiscidae). The model predicts the following evolutionary sequence: (1) cost to females of mating increases, (2) females evolve behavioural resistance to male mating attempts, (3) males evolve devices to overcome female resistance, and (4) females evolve morphological counter-adaptations to the male devices. This model is tested using species of Dytiscidae, in which (1) some species have a very long mating duration while others mate quickly, (2) females of some species resist male mating attempts by swift and erratic swimming when seized by a male, (3) males of some species possess a grasping device in the form of sucker-shaped setae on the legs used to adhere to the pronota or elytra of females prior to mating, and (4) females of some species have a modified dorsal cuticle with irregular sculpturing which appears to interfere with the male adhesive setae. The predicted order of evolution of some of these features was tested in a cladistic analysis of 52 taxa in Dytiscidae and Hygrobiidae using characters from adult and larval morphology and a portion of the gene wingless . The combined analysis resulted in nine most parsimonious cladograms. The consensus cladogram of these indicates that male sucker setae arose a single time in a clade of Dytiscinae. Nested within this clade are five groups with an independently derived, modified dorsal cuticle in females. This pattern of characters in Dytiscinae is consistent with the prediction implied by the model of sexual selection. The utility of wingless as a marker for phylogenetic analysis of diving beetles is discussed, and the resulting phylogeny is compared with previous analyses and current classification.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 359–388.     

Study on the systematic position of Metriini based on characters of the larval head (Coleoptera: Carabidae)

Abstract. Characters of the head of larvae of Metrius contractus Eschscholtz, Ozaenini and Paussini are interpreted phylogenetically. The monophyly of Metriini + Ozaenini + Paussini is substantiated by several synapomorphies such as hyperprognathism and strong constriction of the neck. Ozaenini and Paussini together form the sister-group of Metriini. Ozaenini are paraphyletic. The monophyly of Paussini + Ozaenini excluding Pachyteles is indicated by two possible synapomorphies. Several synapomorphies are shared by Physea + Paussini. Secondary prognathism, large membranous submento-mental area and other derived features are considered autapomorphies of Paussini. Paussini excluding Platyrhopalopsis are characterized by the loss of the palpifer. The monophyly of a group which comprises Geadephaga excluding Trachypachini is suggested by several synapomorphic features. A very basal position of the metriine—paussine lineage within Carabidae is indicated by several plesiomorphic features. A hypopharyngeal filter apparatus with a dense fringe of well-arranged, long hairs is a possible autapomorphy of Anisochaeta. The results of this study do not indicate a close relationship between the metriine—paussine lineage and the tribes Brachinini and Crepidogastrini as has been suggested in recent works.     

Chromosomes of Trachypachus Motschulsky and the evolution of the ancestral adephagan karyotype (Coleoptera)

The family Trachypachidae is a critical group for understanding the evolution of the coleopteran suborder Adephaga. In this article, we report the first karyotypic data on Trachypachus showing a diploid number of 2n = 36 + X (meioformula n = 18 + X) and a single autosomal localization of the rDNA clusters. The evolutionary dynamics of this karyotype are discussed in the light of recent phylogenetic hypotheses of the order Coleoptera. We conclude that chromosome analysis supports a close relationship between trachypachids and the other Geadephaga and that a male karyotype with 36 + X chromosomes may well be considered ancestral for the whole suborder Adephaga.     

Diversity of aquatic and riparian Coleoptera of the Philippines: checklist,state of knowledge,priorities for future research and conservation

The diversity of the aquatic and strictly riparian beetles of the Philippines is reviewed. A checklist (with 317 species and subspecies) of the aquatic and riparian Coleoptera of the Philippines is provided for the first time herein. This checklist covers the following families (number of species and subspecies in parentheses): Hydroscaphidae (1), Gyrinidae (15), Dytiscidae (65), Noteridae (4), Haliplidae (2), Hydraenidae (15), Hydrochidae (2), Spercheidae (1), Hydrophilidae (72), Scirtidae (49), Elmidae (23), Dryopidae (2), Psephenidae (16), Eulichadidae (1), Limnichidae (20), Heteroceridae (5), Malachiidae (5), Lampyridae (15), Nitidulidae (4). A total of 201 species and subspecies (63%) are considered to be endemic to the Philippines. Aquatic/riparian beetle genera and families that are still unrecorded but likely to occur in this country are briefly discussed. Based on estimates at the genus level, it is concluded that about 850 aquatic and riparian species can be expected to occur in the Philippines. The implication of the Philippine biogeographic history for this diversity is discussed. The potential of aquatic/riparian beetles as bioindicators is briefly examined. The dilemma of aquatic invertebrate conservation is analysed and priorities for future research are outlined.