Kelly B. Miller

On the phylogeny of the Dytiscidae (Insecta: Coleoptera) with emphasis on the morphology of the female reproductive system

Characters from adult morphology are analyzed cladistically to infer the phylogeny of the family Dytiscidae. The analysis is based on examination of 233 species of Dytiscidae and several outgroup taxa including members of Noteridae, Amphizoidae, Hygrobiidae and Carabidae. Members of all currently recognized tribes of Dytiscidae are represented except Anisomeriini Brinck, Hydronebriini Guignot and Carabhydrini Watts. Emphasis is placed on identifying informative characters from the female genital system that comprise 34 of the resulting 101 total characters. The consensus of the most parsimonious trees is well resolved and supports recognition of ten subfamilies of Dytiscidae including; Matinae van den Branden, Laccophilinae Gistel, Coptotominae van den Branden, Copelatinae Erichson, Hydroporinae Aube, Agabinae Thomson, Colymbetinae Erichson, Lancetinae van den Branden and Dytiscinae Leach. Also, Hydrodytes Miller, NEW GENUS, is erected and placed in its own subfamily, Hydrodytinae, NEW SUBFAMILY, to include two species previously placed in Agaporomorphus Zimmermann (Copelatinae), H. opalinus (Zimmermann) (NEW COMBINATION) and H. dodgei (Young) (NEW COMBINATION). Hydrodytinae is sister group to Hydroporinae and is diagnosed by the presence of anterior apodemes on the gonocoxae, several characters of the metendosternite (each synapomorphic with Hydroporinae), lack of pseudotetramerous pro- and mesotarsi, lack of a declivitous prosternum and prosternal process, the scutellum visible with the elytra closed (all plesiomorphic), the rami of the female genitalia sinuate and dorsally with an opalescent sheen (each autapomorphic for Hydrodytinae). Matinae is resolved as the sister group to the remaining Dytiscidae. Hyphydrini Sharp is found to be paraphyletic with respect to Pachydrini Bistrom, Nilsson and Wewalka, and the latter is relegated to a junior subjective synonym of the former (NEW SYNONYMY). Hydroporini Aube and Hygrotini Portevin are found to be para- or polyphyletic. No changes are made to the classification of these taxa since character evidence is relatively weak, and taxon sampling within Hydroporinae is inadequate to justify changes. Carabdytes Balke, Hendrich and Wewalka is found to be the sister taxon to the remaining Colymbetinae, and because of its unique combination of characters and phylogenetic placement it is included in its own tribe, Carabdytini Pederzani (RESURRECTED). All other examined tribes of Dytiscidae are monophyletic. The female genitalia are described and figured for numerous taxa across the family, and numerous other characters are described and figured. The evolution of various features of the female genitalia within Dytiscidae is discussed. The resulting phylogenetic hypothesis is compared and contrasted with other phylogenetic proposals.

Cladistic analysis of the tribes of Dytiscinae and the phylogenetic position of the genus Notaticus Zimmermann (Coleoptera: Dytiscidae)

A hypothesis of the phylogeny of the tribes of Dytiscinae is presented based on a cladistic analysis of adult morphological characters. All tribes of Dytiscinae were included with larger tribes represented by multiple genera. Outgroups included members of all major lineages (subfamilies) of Dytiscidae. The matrix consists of 22 taxa and 45 characters. A single most parsimonious cladogram was produced by the analysis. It is concluded from the analysis that Dytiscinae is paraphyletic with respect to the genus Notaticus Zimmermann which has been previously recognized as the only member of the subfamily Aubehydrinae. Its position within the subfamily requires that it be placed within its own tribe, Aubehydrini. Additionally, Dytiscini was found to be paraphyletic, and a new tribe, Hyderodini, is proposed to contain the genus Hyderodes Sharp. Dytiscini is restricted to include only the genus Dytiscus Linneaus. Dytiscinae and all other tribes within the subfamily were found to be monophyletic. The proposed relationships of the tribes of Dytiscinae are Cybistrini + (Dytiscini + (Hyderodini + (Aubehydrini + (Hydaticini + (Eretini + Aciliini))))). Characters discovered to be useful for phylogenetic analysis of the subfamily are illustrated and described. The tribes are diagnosed and a key is presented for distinguishing them.

Revision of the Genus Eretes Laporte, 1833 (Coleoptera: Dytiscidae)

The genus Eretes Laporte is revised. Four species are recognized in the genus; 1) E. australis (Erichson) (= E. punctipennis (MacLeay)), 2) E. griseus (Fabricius) (= E. plicipennis (Motschulsky), = E. succinctus (Klug), = E. moroderi Báguena Corella), 3) E. sticticus (Linnaeus) (= E. punctatus (Zoubkoff), = E. helvolus (Klug), = E. occidentalis (Erichson), = E. conicollis (Wollaston), = E. subcoriaceus (Wollaston), = E. subdiaphanus (Wollaston)) and 4) E. explicitus Miller, sp. n. The taxonomic history of the group is reviewed. The tribe and genus are diagnosed and a key to the species is provided. Each species is diagnosed, its general distribution is provided and important morphological features are illustrated. The larva of E. australis is illustrated and used to diagnose the tribe. Evidence for the sister-group relationship between Eretini and Aciliini and for relationships within the tribe is presented based on characters from adult and larval morphology.

Asymmetrical male mandibular horns and mating behavior in Agathidium Panzer (Coleoptera: Leiodidae)

Males of some species of Agathidium Panzer have a prominent horn on the dorsal surface of the left mandible. The horn is unique in that it is highly asymmetrical. One species, A. marae Miller and Wheeler, has an additional horn on the right side of the frons. The horns are categorized into four general morphological types. Scaling relationships are investigated for two species, A. angulare Mannerheim and A. pulchrum LeConte. These species exhibit a scaling relationship that is strongly discontinuous (sigmoid) with a prominent “switch point”. Measurement data (pronotal width versus mandible height) are fit to a nonlinear regression model to determine the switch points and slopes at the switch points for the populations of each species. Behaviors associated with mating and other behaviors are described for A. pulchrum. Males use a head‐thrusting behavior to dislodge rival males from the substrate. Horned males appear better able to dislodge opponents. Head thrusting is also used less vigorously on females before and after mating.

Revision of the Genus Agaporomorphus Zimmermann (Coleoptera: Dytiscidae)

Abstract The Neotropical genus Agaporomorphus Zimmermann is revised. The genus includes five species, including three new species: A. mecolobus Miller, new species, A. dolichodactylus Miller, new species and A. grandisinuatus Miller, new species. A key is presented for identification of the species. Agaporomorphus inaciculatus Guignot is transferred to the genus Hydrodytes Miller, new combination. Male and female genitalia and other taxonomically important features are illustrated. A phylogenetic analysis of the genus is presented.

Revision and phylogenetic analysis of the New World genus Neoclypeodytes Young (Coleoptera: Dytiscidae: Hydroporinae: Bidessini)

The western North American and northern Central American genus Neoclypeodytes Young is revised. Twenty‐five valid species are recognized in the genus. One additional name, N. luctuosus (Guignot) is treated as species of uncertain status. Eleven new species are described: N. amybethae, N. anasinus, N. astrapus, N. challeti, N. edithae, N. haroldi, N. megalus, N. nanus, N. roughleyi, N. similis and N. tumulus. Six new synonymies are established: N. centralis (Sharp) = N. cinctellus (LeConte); N. substriatus (Sharp) = N. discedens (Sharp); N. americanus (Guignot), N. decoratus (Fall) and N. quadrisignatus (Sharp) = N. fryii (Clark); and N. rugulosus (Guignot) = N. obesus (Sharp). Lectotypes are designated for N. curtulus (Sharp), N. discedens, N. discretus (Sharp), N. lynceus (Sharp), N. obesus, N. ornatellus (Fall), N. pictodes (Sharp), N. plicipennis (Crotch), N. quadrinotatus (Sharp), N. quadripustulatus, N. quadrisignatus and N. substriatus. A key is provided for the known species of Neoclypeodytes. Distribution maps, illustrations of important morphological features and natural history notes are provided for each species. A single possible synapomorphy was found supporting the monophyly of Neoclypeodytes, a pattern of two maculae on each elytron. The perplexing and unresolved relationships of Neoclypeodytes to other bidessine genera are discussed. A cladistic analysis using twenty‐two characters of adult morphology is presented for twenty‐five species of Neoclypeodytes, with Uvarus lacustris (Say) and Liodessus affinis (Say) as outgroup taxa (rooted at U. lacustris). A single most parsimonious cladogram was obtained.

Revision of the Neotropical Genus Hemibidessus Zimmermann (Coleoptera: Dytiscidae: Hydroporinae: Bidessini)

The genus Hemibidessus Zimmermann, 1921 is revised. Six species are recognized in the genus. Two new species are described, H. spirodiscus sp. n. from Bolivia and H. spangleri sp. n. from Argentina. A key for identifying the species is presented. The female genitalia are thoroughly illustrated and described for the first time for any species of Bidessini. Other important diagnostic structures are also illustrated including the male genitalia. A cladistic analysis is presented for 8 species (6 ingroup and 2 outgroup species) and 13 characters. A single most parsimonious cladogram was found.

CALICOVATELLUS PETRODYTES, A NEW GENUS AND SPECIES OF PRIMITIVE VATELLINE DIVING BEETLE (COLEOPTERA: DYTISCIDAE: HYDROPORINAE: VATELLINI) FROM THE MIOCENE BARSTOW FORMATION, SOUTHERN CALIFORNIA, USA

RELATIVELY FEW fossil dytiscids have been described. This is unfortunate since fossils can provide useful phylogenetic and evolutionary information including unique character combinations not present in extant taxa and minimum ages for divergences. However, even when fossils are found, important characters are often not visible since they may be poorly preserved or obscured. The fossil insects present in calcareous nodules from the Miocene Barstow Formation of the Calico Mountains in Southern California are exceptionally well preserved (Palmer, 1957). The original organisms are replaced by silica or other minerals and when the nodules are dissolved in formic acid, the three-dimensional fossil can be retrieved from the resulting residue. These nodules have yielded a wide variety of fossils, including larvae of the dytiscid species Schistomerus californense Palmer, 1957 and numerous other terrestrial and fresh-water arthropods (Palmer, 1957). The purposes of this paper are to describe a new dytiscid genus and species from an exceptionally well-preserved specimen from the Barstow Formation and to present a hypothesis of the phylogenetic placement of the new taxon. Regional Geology.─Beginning in the Miocene, Southern California was the site of extensive faulting and volcanic activity as

Revision of the subfamily Hydrodytinae Miller (Coleoptera: Dytiscidae) with description of a new genus

The New World subfamily Hydrodytinae Miller is revised. Two genera are recognized, Hydrodytes Miller and Microhydrodytes gen. n. Hydrodytes contains three known species, H. opalinus (Zimmermann), H. dodgei (Young) and H. inaciculatus (Guignot). Microhydrodytes contains a single known species, M. elachistus sp. n. Keys are provided to the genera and species in the subfamily. Important morphological features are illustrated for diagnosing the species and a phylogenetic hypothesis is proposed for all species.

Revision of the Nearctic Liodessus affinis (Say 1823) species group (Coleoptera: Dytiscidae, Hydroporinae, Bidessini)

North American members of the Liodessus affinis (Say 1823) species complex are revised. The species group comprises four species. Two new species are described: L. noviaffinis (type locality: Gainesville Forest Insect Lab, Alachua Co., Florida) and L. saratogae (type locality: Saratoga Springs, San Bernardino County, California). Liodessus obscurellus (LeConte 1852), formerly considered a junior subjective synonym of L. affinis, is given specific status. The following synonymies are established: L. affinis microreticulatus (Hatch 1928), L. charlottii (Clark 1862), L. emilianus (Clark 1862), L. erythrostomus (Mannerheim 1852), L. macularis (LeConte 1852), and L. nigrinus (Casey 1884) = L. obscurellus. All of these names were previously treated as junior subjective synonyms of L. affinis. Also, L. youngi (Larson & Roughley 1990) = L. abjectus (Sharp 1882). Lectotypes are designated for L. abjectus, L. charlottii, L. erythrostomus, L. emilianus, L. macularis, L. nigrinus, and L. obscurellus. A neotype is designated for L. affinis. Liodessus nanus (Aube 1838) is considered a species name of uncertain status, but is probably a subjective synonym of L. affinis. A key is provided for the nine known species of North American Liodessus Guignot. The genus Liodessus is diagnosed, and its taxonomic history and questionable status as a natural group are discussed. The L. affinis complex is diagnosed, and its taxonomic history and natural history are discussed. Male genitalia are the only consistently useful structures known for differentiating species in the L. affinis complex. Females are not distinguishable based on currently known morphological features but may be identified using geographic information. Characters used previously, including coloration, punctation and general shape are too variable within and between species to be useful for species diagnosis or delimitation. For each species in the complex the following are provided: a bibliography of the species, discussion of type specimens, taxonomic history and synonymy, diagnosis, variation, etymology (for new species), geographic relationships, natural history, and geographic distribution. Distribution maps and illustrations of important structural features are provided for all species of the complex. For other Nearctic species of Liodessus the following are provided: a brief bibliography of the species, diagnosis, distribution, remarks about bionomics and/or taxonomy, and illustrations of important structural features.