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Last instar larvae of the variegated mud-loving beetle Heterocerus similis Grouvelle are described and illustrated in detail. Comparative notes with earlier instars are also included. Based on the width of the head capsule and the prothorax four different instars were identified; considering that heterocerids show five larval instars, the four instars identified probably correspond to the last four. Larval length was not useful to recognize among different larval stages. The larva of H. similis is compared to that of H. freudei (Pacheco), the only other described South American heterocerid larva. [ABSTRACT FROM AUTHOR]

Larvae of water scavenger beetles (Coleoptera: Hydrophiloidea) are adapted to a wide variety of aquatic habitats, but little is known about functional and evolutionary aspects of these adaptations. We review the functional morphology and evolution of feeding strategies of larvae of the families Hydrophilidae and Epimetopidae based on a detailed scanning electron microscope (SEM) analysis, analysis of video records of feeding behaviour and observations of living larvae. There are two main types of feeding mechanisms: chewing and piercing-sucking. The character mapping using the latest phylogenetic hypothesis for Hydrophiloidea infers the chewing system as the ancestral condition. The piercing-sucking mechanism evolved at least four times independently: once in Epimetopidae (Epimetopus) and three times in Hydrophilidae (Berosini: Berosus + Hemiosus ; Laccobiini: Laccobius group; Hydrobiusini: Hybogralius). The piercing-sucking apparatus allows underwater extra-oral digestion and decreases the dependence of larvae on an aerial environment. A detailed study of the tracheal morphology of the piercing-sucking lineages reveals four independent origins of the apneustic respiratory system, all of them nested within lineages with piercing-sucking mouthparts. We conclude that piercing-sucking mouthparts represent a key innovation, which allows for the subsequent adaptation of the tracheal system, influences the diversification dynamics of the lineages and allows the shift to new adaptive zones. [ABSTRACT FROM AUTHOR]

Phylogenetic analyses testing the monophyly of the tribe Hydrobiusini and the relationships among its genera are performed based on a data matrix including characters of larval morphology and morphometrics, larval chaetotaxy and adult morphology, including eight of the nine hydrobiusine genera plus 15 outgroup taxa. The head chaetotaxy of six genera of the tribe Hydrobiusini is described (Ametor , Hybogralius , Hydramara , Limnohydrobius , Limnoxenus and Sperchopsis). Morphometric characters derived from the head capsule and mouthparts are included. All characters are illustrated in detail. The analyses performed on the above datasets and their combinations reveal the monophyly of the Hydrobiusini except for Hybogralius , and reconstruct the internal topology of the tribe, largely corresponding to results of previous molecular analyses. Hybogralius groups with genera having larvae adapted to underwater feeding in all analyses. The position of the genus Tritonus within the Laccobiini is questioned by our analyses, which suggest a closer relationship with the tribes Hydrophilini or Hydrobiusini. Larval characters are revealed as highly homoplastic, with chaetotaxic characters performing slightly worse than usual larval morphology. Nonetheless, they are phylogenetically informative and useful for testing phylogenetic hypotheses resulting from analyses of molecules or adult morphology. A key to larvae of the genera of the Hydrobiusini is presented. [ABSTRACT FROM AUTHOR]

The primary chaetotaxy of the head capsule and head appendages of the larva of Chaetarthria bruchiBalfour-Browne is described for the first time. Morphometric characters derived from the head capsule and mouthparts are included, together with detailed illustrations of all characters. Chaetotaxy of C. bruchi is compared with that of C. seminulum (Herbst), the only other Chaetarthriini species for which the chaetotaxy has been described. [ABSTRACT FROM AUTHOR]

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Abstract Larvae of water scavenger beetles are found in all types of aquatic and semi-aquatic environments and play an important role in the structure of these communities. Despite their diversity, morphological characters that allow the identification of larvae at species level are usually inconspicuous. In this paper we analyze the head capsule and mouthparts chaetotaxy of hydrophilid larvae belonging to the tribe Berosini, with the purpose of identifying variations on the external sensory organs that may be used for species delimitations. We focus on two species of Berosus Leach (Berosus festivus Berg, 1885 and Berosus patruelis Berg, 1885) and compare larval structures within Berosus and among other genera of Berosini. We include morphometric characters together with detailed illustrations of all characters, SEM images of selected structures and micrographs of a sensory organ present on the inner margin of the first antennomere which is a novelty within larval Coleoptera. Our analysis shows that the number, shape, relative position and organization of sensilla, especially those of labroclypeus and mouthparts, provide diagnostic characters for the separation of Berosus species. Also, we found a new set of characters derived from chaetotaxy that supports current phylogenetic relationships within the tribe Berosini. Most of these chaetic characters are associated with structures that have undergone strong modifications as adaptation to a benthic lifestyle in the clade Berosus + Hemiosus. [ABSTRACT FROM AUTHOR]

The primary and secondary chaetotaxy of the head capsule and head appendages of the three larval instars of Dactylosternum cacti (LeConte, 1855) and Phaenonotum exstriatum (Say, 1835) (Coleoptera: Hydrophilidae: Sphaeridiinae) are described for the first time. Morphometric characters derived from the head capsule, mouthparts and legs are also included, together with detailed illustrations of all characters. Morphology and chaetotaxy of these larvae are compared to that of other described Coelostomatini larvae. [ABSTRACT FROM AUTHOR]

Mature larvae of two species of the riffle beetle genus Austrelmis Brown are described and illustrated for the first time: Austrelmis catamarcensis Manzo and Archangelsky and Austrelmis talampayensis Manzo and Archangelsky. A larval diagnosis for the genus is presented; larvae of both species are compared with each other and with two other previously described and illustrated Austrelmis larvae. [ABSTRACT FROM AUTHOR]

Generic keys for the identification of larvae of Dytiscidae from Argentina are presented. A total of 27 dytiscid genera are recognized-in Argentina, included in 16 tribes and seven subfamilies. Twenty-two of the 27 genera are included in the keys. The remaining five genera could not be included because their larvae are unknown (Bidessonotus Régimbart, Brachyvatus Zimmermann, Hemibidessus Zimmermann, Neobidessus Young) or remain poorly known {Cybister Curtis). The keys are presented in English and Spanish. Morphological as well as chaetotaxic characters were included, and an emphasis was made to include easily seen and identifiable characters. However, due to the small size of many dytiscid larvae, some of the characters mentioned in the keys (especially the chaetotaxic ones) are difficult to visualize through the observation with a stereoscopic microscope. Therefore, the use of a compound microscope for the identification is recommended. [ABSTRACT FROM AUTHOR]

The evolution of four bionomic and morphological characters is compared under five different phylogenetic hypotheses depicting the family relationships of the superfamily Hydrophiloidea (s.sir.). These characters are: adult habitat (aquatic or riparian), larval habitat (terrestrial, aquatic or riparian), type of respiratory system in larvae (holopneustic or metapneustic) and number of abdominal segments in larvae (tenth segment not reduced or tenth segment reduced). Even though no phylogenetic hypothesis is favored above the others, they are evaluated according to how they explain the sequence of state changes of the above mentioned characters, and those that explain this sequence more parsimoniously are brought out. [ABSTRACT FROM AUTHOR]

Abstract All the preimaginal stages of Lancetes marginatus (Steinheil) and third instar larva of L. biremis Říha are described and figured for the first time. Detailed analyses of the morphometry, chaetotaxy and porotaxy are provided, and comparisons with the immatures of other species of the genus are included. The larvae described have multifragmented urogomphi, the only larval synapomorphy that defines the genus Lancetes Sharp. Third instars also present a secondary subdivision in some of the cephalic appendages, which is a synapomorphy of Lancetes plus Dytiscinae. First instar larva of L. marginatus is distinguished from the remaining known first instars of Lancetes by the absence of primary pores FRe and MXa, and the presence of one additional minute seta on the dorsal surface of antennomere 4 and one additional pore on the urogomphus. The third instar of L. marginatus is unique by the absence of secondary dorsal setae on the femur. The pupa of L. marginatus differs from that of L. angusticollis by the presence of fewer setae on the head, pronotum and abdominal terga V to VIII. [ABSTRACT FROM AUTHOR]

The preimaginal stages of the Neotropical species Hydrobiomorpha spinosa (Orchymont) are described and figured for the first time. They are compared to the larvae of the New World species Hydrobiomorpha casta (Say) and to unidentified African and Australian larvae. Bionomical notes on this species are included. [ABSTRACT FROM AUTHOR]

A phylogenetic analysis, at a tribal and subtribal level, of the subfamily Hydrophilinae was conducted. The analysis was based on twenty-nine taxa (twenty-three genera) and 148 characters (fifty-eight from immature stages and bionomics, and ninety from adults). According to the present study, Hydrophilinae is monophyletic, and except for the tribe Hydrophilini which appears as polyphyletic (it includes the subtribes Hydrophilina, Hydrobiina, and Acidocerina), the remaining tribes are monophyletic. The tribes Berosini and Chaetarthriini form the basal clade of Hydrophilinae. One unexpected result is the relationship between the subtribe Hydrobiina and the tribe Sperchopsini, which form a well-supported clade. The final tree has the following structure: (((((Sperchopsini Hydrobiina) (Anacaenini Laccobiini)) Acidocerina) Hydrophilina) (Berosini Chaetarthriini)). The results partially disagree with the phylogeny presented by Hansen, in 1991, which was based mostly on adult characters. Several evolutionary trends are briefly discussed: the types of egg case, the morphology of the clypeolabrum, mouthparts, legs, and breathing adaptations in larvae. [ABSTRACT FROM AUTHOR]

The preimaginal stages of the Neotropical species E. (M.) lampros Knisch, and Enochrus (H.) tremolerasi Knisch, are described and illustrated for the first time. They are compared to the immatures of the Neotropical species E. (M.) vulgaris (Steinheil) and E. (Hugoscottia) scutellaris (Bruch), the Nearctic E. (M.) fimbriatus (Melsheimer) and E. (M.) pygmaeus nebulosus Say, and the Australian E. (M.) maculiceps (MacLeay). Bionomical notes on the two species are included. [ABSTRACT FROM AUTHOR]

Spercheus halophilus n. sp. is described together with its eggcase and larval stages. This is the second Neotropical species for the genus.Comparative notes with adults of related species are included: S. halophilus seems closely related to S. fimbriicollis Bruch, 1915 and S. spangleri Hebauer, 1990. Larvae of S. halophilus show severalimportant differences when compared with those of S. emarginatus (Schaller, 1783) and S. cerisyi Guérin-Meneville, 1842, mostof them related to the mouthparts. This species lives in temporary pools ofwater gathered along the margins of roads running through a large salt flatin Central Argentina. Notes on the biology of this species are also included. [ABSTRACT FROM AUTHOR]

In this contribution we describe and illustrate for the fi rst time, detailed morphology and chaetotaxy of the last instar larva and the pupa of Ora depressa (Fabricius, 1801), and provide diagnostic characters and information on its biology. The last instar larva of O. depressa exhibits the characters traditionally recognized as diagnostic of the genus, i.e. the tip of the mandible obtuse, and the fourth maxillary palpomere long, almost as long as third palpomere. Ora depressa is characterized by a broadly elliptical body, which is widest at the metanotum, being brownish testaceous in color with several brown spots, having the dorsal surface mostly covered with numerous grooved scale-like setae and also several ungrooved scale-like setae, hair-like setae, club-like setae and pore-like sensilla distributed in a specific pattern, and the femur and tibiotarsus bearing a row of natatorial setae. The last instar larva of Ora depressa can be distinguished from those of the other known species of the genus by lobes of clypeolabrum being as long as wide and socket bristles with 2-6 inner teeth. The pupa of O. depressa differs from those of the other known species of the genus in the absence of pronotal horns and by the place where pupation occurs. Ora depressa pupates underwater, hanging from water's surface with the aid of the laterally expanded pronotum which bears hydrophobic setation along the lateral margins. [ABSTRACT FROM AUTHOR]