Accepted by I. Ribera: 30 Jun. 2008; published: 23 Jul. 2008 45

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Fontidessus Miller and Spangler, a new genus of Bidessini from Venezuela (Coleoptera: Dytiscidae: Hydroporinae) with three new species

KELLY B. MILLER1 & PAUL J. SPANGLER2

1Department of Biology and Museum of Southwestern Biology, University of New Mexico, MSC03 2020, Albuquerque, NM 87131 USA. E-mail: kbmiller@unm.edu2Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20560 USA

Abstract

A new genus, Fontidessus n. gen., and three new species F. toboganensis n. sp., F. ornatus n. sp., and F. wheeleri n. sp.,are described from Venezuela. The new genus is similar to Uvarus and Bidessodes but is distinguished from all otherBidessini (including these) by a combination of the following: 1) transverse occipital line absent, 2) basal pronotal striaepresent, 3) basal elytral stria absent, 4) elytral sutural stria faintly present in some specimens, 5) anterior clypeal marginunmodified, 6) elytron without longitudinal carinae, 7) epipleuron without transverse carina at humeral angle, 8) laterallobes of aedeagus two-segmented, 9) habitus elongate, oval, with lateral pronotal and elytral margins nearly continuouslyand shallowly curved, and 10) metatrochanter extremely large relative to metafemur, approximately 0.6 × length ofmetafemur.

Key words: diving beetles, classification, taxonomy, new genus, new species, Venezuela

Introduction

The tribe Bidessini is among the most diverse groups of Dytiscidae. Fortunately, the group has received con-siderable attention at the genus and species level making specimens largely identifiable, though new speciesare discovered regularly. Particularly important work in the group include reviews of the Neotropical taxa(Young, 1967, 1969) and a documentation of the world genera and species (Biström, 1988). Most of the Neo-tropical/Nearctic and Afrotropical genera have been revised in modern times by F. Young and O. Biströmadvancing dramatically an understanding of the diversity in the group. Although species in this tribe are usu-ally distinct, it has a phylogenetically problematic genus-level classification. There are large numbers of gen-era defined largely by either a particular distinct apomorphy or by a unique combination of about five or sixdifferent characters. In the first case, recognition of the genus often results in a probably paraphyletic groupleft behind once the group with the apomorphy is erected. In the second case, it is clear that there is extensivehomoplasy (including losses) in the characters in question, and, therefore, it is not clear how homologous fea-tures are actually distributed among the taxa. It is a difficult taxon at the genus rank. Nevertheless, new taxawith new combinations of features are discovered regularly and must either be placed into an existing genusor a new one. Ideally, the decision about where to place a new species with a distinct character combinationwould be based on a cladistic analysis of the tribe, but such an analysis does not exist and will be a majorundertaking. The following new species from Venezuela represent just such a group of problematic taxa witha unique character combination requiring a new genus to accommodate them.

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Material and methods

Measurements and illustrations. Measurements were taken with an ocular scale on a Wild M3C dissectingmicroscope. Several specimens were measured when possible and an attempt was made to measure the largestand smallest specimen of each species. Measurements include: 1) total length (TL), 2) greatest width acrosselytra (GW), 3) greatest width of pronotum (PW), 4) greatest width of head (HW), and 5) distance betweeneyes (EW). The ratios TL/GW and HW/EW were also calculated. Female genitalia were illustrated for only asingle species, Fontidessus toboganensis, since undamaged portions of this character system were availableonly for this species.

Material. Specimens were examined from the United States National Museum of Natural History, Smith-sonian Institution (USNM, W.E. Steiner). Holotypes and most paratypes were deposited in the USNM andseveral paratypes are in the Museum of Southwestern Biology, University of New Mexico (MSBC, K.B.Miller).

Authorship. Some explanation is required for authorship of this paper and the new taxa described herein.Although no longer able to actively participate in research activities, while previously active in research at theUSNM P.J. Spangler developed numerous unpublished manuscripts. These, and many of the specimens onwhich they were based, were found in his office after his retirement. One of these manuscripts includeddescription of a new genus and species of Bidessini corresponding to the new genus and one of the new spe-cies described here. This manuscript was used, in significant part, as the basis of this paper. His conclusionswere somewhat more limited than those presented here in that he recognized only a single new species in thegenus, whereas, in the first author’s opinion there are at least three involved in the Venezuela material.Whereas credit is certainly due Spangler for his contribution to the paper and discovery of a new genus andspecies, without his direct involvement (he is not able to actively participate in this research at this time), it isuncertain what he might think about the two additional species. Rather than burdening his reputation with tax-onomic conclusions with which he may not agree, the first author has chosen to attribute two species to him-self alone and the genus and species Spangler clearly believed to be new to both authors.

Fontidessus Miller and Spangler, new genus(Figs 1–17)

Type species. Fontidessus toboganensis Miller, new species by current designation.Diagnosis and description. Fontidessus is clearly a member of the tribe Bidessini based on the bi-seg-

mented lateral lobes of the aedeagus (Figs 10, 13, 16) (Biström, 1988) and the presence of a distinct spermath-ecal spine (Fig. 17) (Miller, 2001). Fontidessus differs from other genera in the tribe by the combination of: 1)transverse occipital line absent (Figs 1–3), 2) basal pronotal striae present (Figs 1–3), 3) basal elytral striaabsent (Figs 1–3), 4) elytral sutural stria faintly present in some specimens (e.g. Fig. 1), 5) anterior clypealmargin unmodified, 6) elytron without longitudinal carinae, 7) epipleuron without transverse carina athumeral angle, 8) lateral lobes of aedeagus two-segmented (Figs 10, 13, 16), 9) habitus elongate, oval, withlateral pronotal and elytral margins nearly continuously and shallowly curved (Figs 1–3), and 10) metatro-chanter extremely large relative to metafemur, approximately 0.6 × length of metafemur (Fig. 4).

This genus is most similar to the genera Uvarus Guignot and Bidessodes Régimbart (to which it keys inBiström’s 1988 key to bidessine genera). From Bidessodes it differs by 1) dorsum not iridescent, and 2) metat-ibiae without natatory setae and metatarsi with few natatory setae. Bidessodes appears to be a monophyleticgroup. Although some of its members have dramatic modifications to the male legs or genitalia, they aresuperficially quite similar and have similar iridescence and color pattern on the dorsal surface. Fontidessusspecimens lack these features. Despite the absence of a cladistic phylogenetic analysis, Fontidessus appears tobe clearly outside Bidessodes.

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From Uvarus, Fontidessus genus differs in lacking basal elytra striae and natatory setae. It is, however,quite similar to Uvarus genus in most characters and general features such as shape, size and coloration. Theproblem with these observations is that Uvarus is a heterogeneous group with a worldwide distribution.Within Bidessini it is the “trashcan” group that includes those taxa without an occipital line but also withoutany unifying synapomorphy. Placing these new species in Uvarus would require an expansion of an alreadyproblematic group to include a new character combination. It seems more desirable to place these species in anew genus until the classification of the Bidessini can be more thoroughly tested (see Discussion below).

FIGURES 1–7. Fontidessus species. 1–3) Dorsal habitus, 1) F. toboganensis, 2) F. ornatus, 3) F. wheeleri. 4) F. tobogan-ensis, left metatrochanter and metafemur, anterior aspect. 5–7) prosternal process, 5) F. toboganensis, 6) F. ornatus, 7) F.wheeleri. Scale bar a = 1.0mm for Figs 1–4. Scale bar b = 0.1mm for Figs 5–7.

Etymology. This genus is named Fontidessus from the Latin word fontis, meaning “spring,” referring tothe seepage-like habitat of the type locality of the type species, and dessus, a common root for genus names inthe tribe Bidessini

Distribution and habitat. The genus is known from three sympatric species from only a single site inVenezuela (see type localities below). In each case, however, the species do not appear to occupy typical openwater. Instead they appear to occur in seeps or shallow water at stream margins.

Discussion. The genera of Bidessini are currently defined based on the combination of several characterssuch as the presence or absent of an occipital line, basal sutural and pronotal striae, epipleural carinae, elytracarinae and more subjective characters such as general shape. Because of the nature of the various combina-tions it is clear that homoplasy, or loss, is exhibited in many of the characters throughout the tribe. There hasbeen only limited cladistic testing of these characters (e.g. Miller et al., 2006). When new species are discov-ered with a new combination of characters, such as those described here, it is not easy to decide whether toerect a new genus or expand the definition of existing genera (which may require synonymy with other gen-era). It seems best, in the absence of cladistic testing of relationships and putative homologies, to place anom-alous species in new genera to draw attention to their unique character combination until such time as thegenera can be phylogenetically revised. In further support of the placement of this taxon outside both Uvarusand Bidessodes, a recent molecular phylogenetic analysis of Dytiscidae by Ribera et al. (2008) included atleast one member of this new genus. According to M. Balke (personal communication), “unknown Bidessinia” in that analysis (MB1171, Ribera et al., 2008) is the species described here as F. toboganensis. In theiranalysis F. toboganensis is resolved with two other unidentified Bidessini and well removed from eitherUvarus or Bidessodes (Ribera et al., 2008).

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Key to the species of Fontidessus Miller and Spangler, new genus

1 Size small (TL < 1.4mm); prosternal process apically pointed (Figs 6, 7) .................................................2- Size larger (TL > 1.4mm); prosternal process apically truncate (Fig. 5).......................................................

....................................................................................... F. toboganensis Miller and Spangler, new species2 Prosternal process moderately elongate, lateral margins apically evenly tapered to pointed apex (Fig. 6);

elytral maculations (Fig. 2) pale brown-yellow, diffuse and indistinctly demarcated; male median lobe notapically bifid (Fig. 11), with small brush of setae subapically on ventral margin (Fig. 12)................................................................................................................................................ F. ornatus Miller, new species

- Prosternal process elongate, lateral margins apically slightly concave to sharply pointed apex (Fig. 7); ely-tral maculations (Fig. 3) bright yellow, distinctly demarcated; male median lobe apically broad and deeplybifid (Fig. 14), without small brush of setae (Fig. 15) ................................F. wheeleri Miller, new species

Fontidessus toboganensis Miller and Spangler, new species(Figs 1, 4, 5, 8–10, 17)

Type locality. Venezuela, Territorio Federal Amazonas, 40km S Puerto Ayacucho, at El Tobogán, Coromoto.Diagnosis. This is the largest known species in the genus (TL > 1.4mm). The prosternal process is moder-

ately broad and parallel-sided and has the apex broadly truncate (Fig. 5). The male genitalia are distinctivewith the median lobe elongate, slender and broadly recurved in lateral aspect (Fig. 9). There is an elongateventral sclerite that fits into the ventral groove of the median lobe (Fig. 9).

Description. Measurements. TL = 1.5–1.6 mm, GW = 0.8–0.9 mm, PW = 0.6–0.7 mm, HW = 0.4–0.5mm, EW = 0.3–0.4 mm, TL/GW = 1.8–1.7, HW/EW = 1.6–1.7. Body (Fig. 1) oval, elongate; lateral outlinenearly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral marginsof elytron evenly and gently curved.

Coloration. Head yellow brown, pronotum yellow brown, brown medially along posterior margin (Fig.1); elytron brown with the following yellow maculae: 1) a basal macula in a band extending from lateral tosutural margins, posterior margin of macula irregular, 2) a lateral longitudinal macula at humeral angle, 3) anarrow longitudinal macula along lateral margin, and 4) a subtriangular subapical macula (Fig. 1). Ventral sur-faces of thorax and abdomen brown except prosternum, prosternal process, propleuron and pronotal epipleu-ron yellow-brown; appendages yellow to yellow-brown.

Sculpture and structure. Head with very fine, inconspicuous, irregular punctation, surface between punc-tures shiny with indistinct microsculpture in the form of small cells; eyes medium in size (Fig. 1, HW/EW =1.6–1.7). Pronotal surface similar to that of head; with posterior angles obtuse; lateral bead narrow, of evenwidth throughout; pronotal striae finely incised, extending nearly 1/2 distance across pronotum (Fig. 1).Elytron with anterolateral angle obtuse, not extended anteriorly (Fig. 1); surface similar to pronotum. Proster-nal process broad, lateral margins subparallel, apex of process broadly rounded (Fig. 5); metacoxal processwith lateral lobe minute. Pro- and mesotarsi relatively narrow in both male and female, but slightly broader inmale.

Male genitalia. Median lobe in ventral aspect extremely slender and long, apex slender and sharplypointed (Fig. 8); in lateral aspect narrow, extremely slender and long in apical half, abruptly curved mediallyto sharply pointed, recurved apex (Fig. 9); with elongate, slender dorsal sclerite (Fig. 9). Lateral lobe in lateralaspect broad basally, bent medially with apical segment elongate and parallel sided to narrowly rounded apex(Fig 10).

Female genitalia (Fig. 17). Bursa copulatrix elongate and narrow; spermathecal duct long, slender, some-what coiled, expanded prior to receptacle; receptacle small, about half size of spermatheca, intermediate duct

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between receptacle and spermatheca broad; spermatheca globular, spermathecal spine prominent, but notelongate; fertilization duct elongate, tightly curved in spiral, attaching to large fertilization sac; vagina elon-gate, moderately narrow; gonocoxae elongate, slender with abrupt, small, triangular expansion at apex (Fig.17).

FIGURES 8–17. Fontidessus species. 8–10) F. toboganensis, male genitalia, 8) median lobe, dorsal aspect, 9) medianlobe, right lateral aspect, 10) right lateral lobe, right lateral aspect. 11–13) F. ornatus, male genitalia, 11) median lobe andleft lateral lobe, dorsal aspect, 12) median lobe, right lateral aspect, 13) right lateral lobe, right lateral aspect. 14–16) F.wheeleri, male genitalia, 14) median lobe and left lateral lobe, dorsal aspect, 15) median lobe, left lateral aspect, 16) rightlateral lobe, right lateral aspect. 17) F. toboganensis, female genitalia, ventral aspect. Scale bars = 0.1mm.

Etymology. The species name is derived from the name of the type locality, El Tobogán.Distribution and habitat. According to notes discovered in P.J. Spangler’s office: “The series of [Fon-

tidessus toboganensis] was collected from seepage areas alongside a cascade. The specimens were obtainedby pulling matted plant roots from granitic bedrock and using an aspirator to suck up the water that accumu-lated in rock depressions as runoff from the roots. The dirty concentrated residue was then filtered throughfine-meshed, nylon cloth and the very small adults and larvae were again aspirated as they crawled out of theresidue.”

Label data indicate the collection of specimens of the species from the following habitats: “seep,” “sunlitstream”, “bare rock streambed in sunlight; beneath wet leaves at margin,” “sunlit stream; slow water oversand and gravel,” and “leaves from stream.”

Material examined. HOLOTYPE in USNM: male labeled, “VENEZUELA: T.F. Amazonas PuertoAyacucho (40km.S) El Tobogán, Cano Coromoto 26 January 1989/ seep at upper shelter collected by PJSPan-gler RAFaitoute&CBBarr/ HOLOTYPE: Fontidessus toboganensis Miller and Spangler, 2008 [red label withdouble black line border].” PARATYPES, 250 total, all with same locality data as holotype, 11 with same col-lecting date as holotype; 1 with 22 February 1986; 21 with 25 February 1986; 24 with 21 January 1985; 1 with16 November 1987; 192 with 23 January 1989.

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Fontidessus ornatus Miller, new species(Figs 2, 6, 11–13)

Type locality. Venezuela, Territorio Federal Amazonas, 40km S Puerto Ayacucho, at El Tobogán, Coromoto.Diagnosis. This species is smaller than F. toboganensis (TL < 1.3mm), but is similar in size (though

slightly smaller) and external appearance to F. wheeleri. Fontidessus ornatus has the prosternal process mod-erately elongate with the lateral margins in the apical portion straight and evenly tapered to the pointed apex(Fig. 6). The pale regions on the elytron are diffuse and poorly demarcated and are yellow-brown unlike F.wheeleri which have the elytral maculae brighter yellow and more clearly demarcated. The male genitalia arediagnostic with the median lobe slender and elongate with a subapical brush of setae on the ventral margin(Fig. 12).

Description. Measurements. TL = 1.1–1.2 mm, GW = 0.6–0.7 mm, PW = 0.6–0.7 mm, HW = 0.4–0.5mm, EW = 0.1–0.2 mm, TL/GW = 1.8–1.9, HW/EW = 1.5–1.6. Body (Fig. 2) oval, elongate; lateral outlineslightly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral marginsof elytron evenly and gently curved.

Coloration. Head yellow brown, darker in region near medial margins of eyes; pronotum yellow brown,diffusely brown medially along posterior margin and in narrow band along anterior margin; elytron brownwith diffuse yellow pattern, yellow basally, laterally along about ¾ length of elytra and in subtriangular sub-apical area (Fig. 2). Ventral surfaces of thorax and abdomen brown except prosternum, prosternal process,propleuron and pronotal epipleuron yellow-brown; appendages yellow to yellow-brown.

Sculpture and structure. Head with very fine, inconspicuous, irregular punctation, surface between punc-tures shiny with indistinct microsculpture in the form of small cells; eyes medium in size (Fig. 2, HW/EW =1.5–1.6). Pronotal surface similar to that of head; with posterior angles obtuse; lateral bead slender, of evenwidth throughout; pronotal striae finely incised, extending nearly 1/2 distance across pronotum (Fig. 2).Elytron with anterolateral angle obtuse, not extended anteriorly (Fig. 2); surface similar to pronotum but withmicrosculpture more indistinct. Prosternal process relatively narrow, lateral margins tapered to narrowlyrounded apex (Fig. 6); metacoxal process with lateral lobe minute. Pro- and mesotarsi relatively narrow inboth male and female.

Male genitalia. Median lobe in ventral aspect slender, elongate and with lateral margins parallel topointed apex (Fig. 11); in lateral aspect moderately broad at base, curved, with apical portion evenly taperedto pointed apex, subapically with small brush of setae (Fig. 12). Lateral lobe elongate, expanded apically,broadly rounded at apex, with series of long setae along dorsal margin (Fig 13).

Etymology. The species name is derived from the Greek root orno, meaning “adorned,” for the attractivecoloration characterizing this species.

Distribution and habitat. The species is known only from the type locality. Label data indicated the fol-lowing habitats; “seep,” and “bare rock streambed.”

Material examined. HOLOTYPE in USNM: male labeled, “VENEZUELA: T.F. Amazonas PuertoAyacucho (40km.S) at Tobogán, 22Feb1986 P.J. Spangler, Colln.#6/ Bare rock streambed in sunlight; beneathwet leaves at margin/ HOLOTYPE: Fontidessus ornatus Miller, 2008 [red label with double black line bor-der].” PARATYPES, 14 total; 3 with same label data as holotype; 9, Venezuela, T.F. Amazonas, PuertoAyacucho, 40km S El Tobogán, Caño Coromoto, 23 January 1989, seep at upper shelter, P.J. Spangler, R.A.Faitoute, and C.B. Barr; 2, same except 26 January 1989.

Fontidessus wheeleri Miller, new species(Figs 3, 7, 14–16)

Type locality. Venezuela, Territorio Federal Amazonas, 40km S Puerto Ayacucho, at El Tobogán, Coromoto.

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Diagnosis. This species is smaller than F. toboganensis (TL < 1.4mm), but is similar in size (thoughslightly larger) and external appearance to F. ornatus. Fontidessus wheeleri has the prosternal process elon-gate with the lateral margins slightly concave and tapered to sharply pointed apex (Fig. 7). The pale regions onthe elytron are brighter yellow and more clearly demarcated in F. wheeleri than in F. ornatus which have theelytral maculae more pale and diffuse. The male genitalia are diagnostic with the median lobe broad anddeeply bifid in ventral aspect (Fig. 14).

Description. Measurements. TL = 1.2–1.3 mm, GW = 0.6–0.7 mm, PW = 0.5–0.6 mm, HW = 0.4–0.5mm, EW = 0.2–0.3 mm, TL/GW = 1.7–1.8, HW/EW = 1.6–1.7. Body (Fig. 3) oval, elongate; lateral outlineslightly continuous between pronotum and elytron; lateral margins of pronotum gently curved; lateral marginsof elytron evenly and gently curved.

Coloration. Head yellow brown, brown along posterior margins and medial margins of eyes; pronotumbroadly brown along posterior margin, narrowly dark brown along anterior margin; elytron brown with thefollowing yellow maculae: 1) a basal macula in an irregular band extending posteriorly along suture at medialmargin, 2) a lateral longitudinal macula posterior to humeral angle, broader anteriorly and extending posteri-orly in narrow band to near apex, 3) a subtriangular subapical macula (Fig. 3). Ventral surfaces of thorax andabdomen dark brown except prosternum, prosternal process, propleuron and pronotal epipleuron yellow-brown; appendages yellow to yellow-brown.

Sculpture and structure. Head with very fine, inconspicuous, irregular punctation, surface between punc-tures shiny, without distinct microsculpture; eyes medium in size (Fig. 3, HW/EW = 1.6–1.7). Pronotal sur-face similar to that of head, with posterior surface with fine microsculpture; with posterior angles obtuse;lateral bead slender, of even width throughout; pronotal striae finely incised, extending nearly 1/2 distanceacross pronotum (Fig. 3). Elytron with anterolateral angle obtuse, not extended anteriorly (Fig. 3); surfacesimilar to pronotum, with microsculpture indistinct. Prosternal process elongate and slender, lateral marginsslightly concave, apex of process rounded (Fig. 7); metacoxal process with lateral lobe small. Pro- and meso-tarsi relatively narrow in both male and female, but slightly broader in male.

Male genitalia. Median lobe in ventral aspect very broad, deeply bifid, with branches broad, subapicallystrongly constricted on lateral margins, apices sharply pointed (Fig. 14); in lateral broad at base, irregularlynarrowed to sharply pointed apex (Fig. 15). Lateral lobe narrow at base, medially expanded, apical portionparallel-sided to slightly expanded, broadly rounded apex, with small series of elongate setae along dorsalmargin (Fig 16).

Etymology. This species is named in honor of my good friend and fellow coleopterist, Dr. Quentin D.Wheeler, Arizona State University.

Distribution and habitat. The species is known only from the type locality. Label data indicate the fol-lowing habitats; “seep,” and “bare rock streambed.”

Material examined. HOLOTYPE in USNM: male labeled, “VENEZUELA: T.F. Amazonas PuertoAyacucho (40km.S) at Tobogán, 22Feb1986 P.J. Spangler, Colln.#6/ Bare rock streambed in sunlight; beneathwet leaves at margin/ HOLOTYPE: Fontidessus wheeleri Miller, 2008 [red label with double black line bor-der].” PARATYPES, 1, same as holotype except 23 January 1989, seep at upper shelter, P.J. Spangler, R.A.Faitoute and C.B. Barr, colrs.

Acknowledgments

Special thanks to Warren E. Steiner for his help with the Paul J. Spangler material at the USNM and for com-ments on this and other projects. Thanks to Andrew E.Z. Short and William Shephard for discussion of thisand other projects related to the Spangler laboratory. Thanks to Olof Biström for insightful comments andreview of the manuscript. Portions of this work were funded by NSF grants #DEB–9983195, #DEB–0329115,and #DEB–0515924.

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