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Nepidae(Hemiptera)oftheUnitedStatesandCanada

ArticleinAnnalsoftheEntomologicalSocietyofAmerica·January1994

DOI:10.1093/aesa/87.1.27

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SYSTEMATICS

Nepidae (Hemiptera) of the United States and Canada

ROBERT W. SITES1 AND JOHN T. POLHEMUS2

Ann. Entomol. Soc. Am. 87(1): 027-042 (1994)ABSTRACT Seventy-two years have elapsed since the most recent synoptic treatment ofNorth American Nepidae. This paper updates our present knowledge and brings togetherinformation on the family from various sources. Notes on the biology and ecology ofNepidae, a redescription of Ranatra texana Hungerford, and an illustrated key to the 13species of Nepidae of the United States and Canada are provided. Range extensions,distribution maps, diagnoses, and synonymies also are given.

KEY WORDS Nepidae, waterscorpion, key

THE KNOWN WATERSCORPION fauna of the con-tinental United States and Canada comprises 13extant species in three genera (Polhemus 1988),two fossil Ranatra species from the McKittrickTar Pits (Pierce 1948, Miller 1983), and one fossilNepa species from Florissant shale beds in Col-orado (Hungerford 1932). Of the extant fauna, thegenus Nepa is monotypic in North America andoccurs throughout the eastern United States andCanada and into the midwest; Curicta is repre-sented by two species in the south and south-west; and Ranatra by 10 species with ranges thatvary from an isolated limestone sink in Arizona(R. montezuma Polhemus) to transcontinental(R. fusca Palisot de Beauvois).

The Nepidae were among the first aquaticbugs studied by early naturalists. The first fig-ures of nepids we have found are two excellentfigures of Ranatra by Aldrovandi (1602, repeatedin 1638) and crude woodcuts by Moufet (1634).Frisch (1728) provided good figures of both Nepaand Ranatra; however, Swammerdam (who diedin 1680) gave us the first excellent anatomicalstudies and drawings of these two genera in hisposthumous Biblia Naturae (1737-1738). Sincethen, the morphology of Ranatra has been stud-ied by several workers, most notably Dufour(1821, 1833; both Nepa and Ranatra), Locy(1884), Marshall & Severin (1904), and Neiswan-der (1925), and more specialized studies by Par-sons (1972, 1974). The morphology of Nepa hasbeen more intensively studied, with contribu-tions by a number of scientists reviewed in theexcellent work of Hamilton (1931). Other thanbrief notes and several figures in Hungerford(1922) and Wiley (1922,1924), the morphology of

1 Wilbur R. Enns Entomology Museum, Department of En-tomology, University of Missouri, Columbia, MO 65211.

2 University of Colorado Museum, 3115 S. York, Englevvood,CO 80010.

Curicta remained essentially unstudied untilKeffer (1991).

Since the first natural history of American ne-pids (Uhler 1884), the literature concerning biol-ogy and ecology of North American Nepidae hasbeen summarized or reported by various authors(e.g., Hungerford 1920, Torre-Bueno 1923, Rad-inovsky 1964, Bobb 1974, Weissmann 1986), andMenke presented an excellent review in 1979.More recently, several life history papers (Pack-auskas & McPherson 1986, McPherson & Pack-auskas 1987), a series of papers concerning eco-logical aspects of R. montezuma (specificallynocturnal planktonic behavior [Blinn et al.1982], parameters pertaining to the eggs [Blinn& Runck 1989], population dynamics and sec-ondary production [Runck & Blinn 1990], forag-ing ecology [Runck & Blinn 1992], and the im-pact of prey behavior and density on foragingstrategy [Blinn et al. 1993]), and several distribu-tion notes (e.g., DuBois 1978, Cochran et al.1992) have been added to the literature.

Much of the literature dealing with NorthAmerican Nepidae has focused on taxonomy.Hungerford (1922) contributed the first majorsynoptic treatment of North American Nepidae,which included biological information, keys tospecies, descriptions of new species, and correc-tions of nomenclatural errors in Kirkaldy & TorreBueno (1909). Kuitert (1947) revised the Ameri-can Nepidae, but only fragments of this disserta-tion were published (Kuitert 1949a,b). Subse-quently, several emendations to the NorthAmerican fauna have been published. Specifi-cally, R. annulipes Stal has been removed be-cause it is neotropical (Polhemus 1988); and R.spatulata, described by Kuitert (1949a) from aKey West, FL, specimen, was considered by Pol-hemus (1976) to be a mislabeled African speci-men. Ranatra texana was described by Hunger-ford (1930) from Texas on the basis of only onemale specimen, and R. montezuma was de-

0013-8746/94/0027-0042302.00/0 © 1994 Entomological Society of America

28 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 87, no. 1

scribed by Polhemus (1976) from Arizona. Morerecently, Stys & Jansson (1988) presented aworld checklist of all Nepomorpha (at and abovethe generic level), and Polhemus (1988) pre-sented all synonymies, provided a brief discus-sion of biology, and listed published state andprovince records for the Nepidae of the UnitedStates and Canada.

Presented herein are notes on the biology andecology of Nepidae; a redescription of R. texana;an annotated list of species; distributions includ-ing range extensions; and an updated, illustratedkey to the United States and Canadian species ofNepidae.

Biology and Ecology

The immature stages of Nepa and Ranatrahave been the subject of many studies: Hinton(1961, 1970) reported on egg structure and func-tion, Davis (1961) described the hatching pro-cess, Holmes (1907) reported on various aspectsof Ranatra nymphs, Hoffmann (1925) showedthat Nepa has only four instars, and Cloarec(1976) demonstrated the importance of mechano-reception in predation behavior. Packauskas &McPherson (1986) and McPherson & Packauskas(1987) provided descriptions for R. fusca and N.apiculata, respectively; the latter oviposits inmud. Oviposition is endophytic for many speciesof Ranatra, including R. montezuma (Blinn &Runck 1989) and R. quadridentata Stal (Holmes1907), although Hoffmann (1930) stated that R.chinensis Mayr oviposits in mud banks, andPackauskas & McPherson (1986) reported that R.fusca oviposits in mud banks devoid of vegeta-tion.

Adults of most New World species of Ranatrapossess a well-developed stridulatory mecha-nism, consisting of serrations on the fore coxalcavity that contact coxal ridges, which appear tobe sclerotized setae (Torre Bueno 1905a). Theonly New World species known to lack stridula-tory structures are R. texana, R. kirkaldyi TorreBueno, R. signoreti Montandon, and R. parvulaKuitert. Further, stridulatory structures are ab-sent in all Old World species examined. Nymphsof Ranatra also possess the stridulatory mecha-nism, a rare occurrence in aquatic insects (Aiken1985) and unknown in any other aquatic het-eropteran. Indeed, the possession of a stridula-tory apparatus in both nymphs and adults may beunique in aquatic insects.

Although nepids exhibit a preference for lenticsituations, habitat selection may be generalizedfor each of the three North American nepid gen-era. Curicta and Nepa typically occur alongmuddy shorelines of spring-fed bodies of water,where their dark-colored, flattened bodies areparticularly well adapted for concealment inmud. Nepa also is found in sparse to dense veg-etation (Torre Bueno 1905b, Severin & Severin

1911a, Lindeman 1941) and under leaves orstones in shallow water (Uhler 1884, Torre-Bueno 1923); DuBois (1978) found Curictaclinging to the side of a submerged log in astream. Long series of both genera have beencollected, often by hand, along the very shallowedges of streams and ponds, where the bugsblend with leaf litter. Specimens of Curicta andNepa are difficult to collect using traditionalaquatic insect net techniques. Although TorreBueno (1905b) recommended sweeping a netover these insects several times to disturb andmake them float into it, moving a stick laterally,held lengthwise against the mud substratum,will usually dislodge the waterscorpions, andthey are then easily noticed as they attempt toregain their original position.

Ranatra is found among aquatic vegetation,debris, and overhanging vegetation that extendsinto the water, where it is most easily collectedby sweeping an aquatic net vigorously throughthe vegetation. Ranatra sometimes occurs indeep water, such as swimming pools or largestock tanks, and has been seen swimming awk-wardly. If emergent vegetation such as reeds orcattails is present, Ranatra clings to it, movingdown the stems to hide during the day and re-turning to the surface during the night. Nepidspossess "static sense organs" that keep them ori-ented correctly in the water (Baunacke 1912,Thorpe & Crisp 1947). Because nepids exhibitdeath-feigning, they appear very sticklike andcan be difficult to detect when collecting. Thepropensity for nepids to undergo death-feigningis well documented for both Nepa (Hamilton1931) and Ranatra (Holmes 1906; Severin &Severin 1911a,b; Abbott 1940; Larson 1949a,b).After several minutes in a dry situation, theybegin moving in an apparent attempt to locatewater and are then most easily separated fromplant debris. Alternatively, by placing thedebris back into the water, much plant materialwill sink, whereas specimens of Ranatra usuallywill float and begin to move, and are easily de-tected.

Cloarec (1986 and references therein) exten-sively studied many aspects of Ranatra develop-ment, behavior, and prey capture. Blois & Cloarec(1983) demonstrated a density-dependent prefer-ence for prey size. Prey may be taken from thewater surface (Radinovsky 1964, Weissmann1986); J.T.P. (unpublished data) observed a spec-imen of R. fusca take a small, live fly from thesurface, and Packauskas & McPherson (1986) re-ported R. fusca preying on water striders. Themajor dietary item of R. montezuma in Monte-zuma Well is an endemic amphipod, and, becausefish are absent in this closed ecosystem, R. mon-tezuma is the ultimate consumer with a high sec-ondary production rate (Runck & Blinn 1992).Weissmann (1986) proposed the use of Ranatrafor mosquito control; Hoffmann (1930) reared R.

January 1994 SITES & POLHEMUS: NEPIDAE OF UNITED STATES AND CANADA 29

chinensis entirely on a diet of mosquitoes, butnoted that large mosquito larvae sometimes killearly instars. Evaluations of the predation effi-ciency of Nepidae on mosquito larvae havebeen provided by Ouda et al. (1986) and Chock-alingam & Somasundaram (1987). Extensive pre-dation on carp eggs by R. linearis L. in someBritish ponds resulted in the recommendationthat the ponds be drained and restocked with fish(Anonymous 1878). There are many other recordsof predation on fish (e.g., Ormerod 1878, Rao1976, Bisht & Das 1981) and tadpoles (Hoffmann1930).

An eyeless Nepa species, recently discoveredin a Romanian cave, is the first known troglobiteamong the aquatic Heteroptera (Sarbu & Popa1992). In that closed cave system, there is novegetation, and Nepa is the ultimate consumer.

Curicta, Nepa, and Ranatra disperse by noc-turnal flights and colonize temporary habitats,although actual observations of flight are rare.It was long thought that Nepa was incapableof flight because specimens were found withdegenerated flight muscles; however, Larsen(1949b) stated that functional flight musculaturedoes exist, summarized flight observations forNepa, and illustrated how flight occurs in Rana-tra (see also Torre Bueno [1906]). Ranatra willfly at night from an uncovered aquarium if a stickis available for it to leave the water. Near LakeP6tzcuaro in Mexico, a hotel swimming pool wasrecolonized on successive nights by Curictascorpio Stal (J.T.P., unpublished data). Nepa alsois apparently able to estivate, burying and encas-ing itself in mud (Wood 1884, Larimore et al.1959).

Taxonomy

De Carlo (1967) divided Nepidae into two fam-ilies, the Nepidae and Ranatridae, and under thelatter proposed the subfamilies Curictinae andRanatrinae (De Carlo 1968). This concept wasrejected by Menke & Stange (1964), Lansbury(1974a), and Stys & Jansson (1988). We concurwith Stys & Jansson that there is one family,Nepidae, with two subfamilies, Nepinae andRanatrinae, the former containing the tribes Cu-rictini and Nepini. Further, Keffer & McPherson(1993) reported the copulatory posture of Curictaand concluded that nepid copulatory posturemay be of subfamilial significance.

Lee (1991) proposed Miyamotoa as a subgenusof Ranatra based on characters of the male gen-italia; this is a preoccupied name, since replacedby Syoitia (Lee 1992). The subgenus was pro-posed to include three North American and oneMexican species (Ranatra australis Hungerford[type species], R. fusca [as americana Montan-don], R. quadridentata, and R. operculata Kuit-ert). Although Lee's study included both OldWorld and New World species, only seven of the

approximately 110 species worldwide were ex-amined. S. L. Keffer has (in progress) an exhaus-tive study of the phylogeny of Nepidae based ondetailed examination of the male genitalia of al-most all species worldwide. Preliminary resultsof that study support the separation of the abovespecies (and others) into a group separate fromthe type species of Ranatra sensu strictu, R. lin-earis; however, several other equivalent groupsmust also be recognized, including one with R.kirkaldyi along with some South American spe-cies. We believe the recognition of genus-groupnames for any of these entities before the com-pletion of Keffer's study is premature, because itwould either require proposing genus-groupnames at this time for all of Keffer's groups orresult in paraphyletic clades. Thus, althoughLee's (1991) proposal has merit, a possible endresult of Keffer's studies is the establishment ofequivalent groups within Ranatra without nam-ing them subgenera and in that event, the genus-group name Syoitia would be placed as a syn-onym of Ranatra. For these reasons, we treatRanatra in this work as a single genus withoutsubordinate taxa.

The general morphology of Nepidae has beenadequately treated and illustrated by Hunger-ford (1922), and the male genitalia were dis-cussed in detail by Lansbury (1974b). We gener-ally have followed the structural nomenclatureof Hungerford (1922), the last definitive revisionof North American species; however, for malegenitalia we follow the more modern terminol-ogy of Lansbury (1974a). As a result, two malegenitalia terms of Hungerford (intromittentorgan and clasper) are herein referred to asposterior diverticulum and paramere, respec-tively.

A number of attempts have been made to keyat least part of the waterscorpion fauna of NorthAmerica (e.g., Blatchley 1926, Herring 1951b,Usinger 1974), but none addressed the entirefauna including R. texana and R. montezuma. DeCarlo (1972) contributed a key to the New Worldspecies of Ranatra (including R. texana but be-fore the description of R. montezuma) (Englishtranslation of the couplets available fromR.W.S.); however, the key is difficult and in someinstances uses relative characteristics. Lans-bury's (1972) key to Oriental Ranatra was pro-posed by Menke (1979) as a model to follow;however, those characters have not been consis-tently appropriate for the North American spe-cies. Other than for eggs (Hinton 1962), keys toimmature stages are lacking.

Waterscorpions are notorious for much in-traspecific variability, particularly with regard toseveral key characters. For example, the lengthsof the metaxyphus and the projection of the pen-ultimate antennal segment are quite variable.This variability led Bennett (1987) to suggesthybridization, and he showed character clines

30 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 87, no. 1

for several species. Because of this variability,occasional individuals will not key correctly;thus, when possible, series of specimens shouldbe collected for many reasons, including to facil-itate characterization of the population and for amore confident use of the key.

Distinction between the parapatric R. brev-icollis Montandon and R. fusca may be quitedifficult. The suite of characters historically usedto distinguish these species is generally unreli-able because of the high level of intraspecificmorphological variability in both species. Usu-ally, the morphology of the penultimate antennalsegment is diagnostic (see couplet 11); however,nepid antennae are variable. Nonetheless, wherethe ranges of the species overlap (i.e., mid- tosouthern California), morphological divergenceis evident in the structure of the metaxyphus.Elsewhere in the range of R. fusca, the expres-sion of the metaxyphus is quite variable. A key toidentify California specimens was presented byMenke (1979); those characters have not beenincorporated into the key presented here, butare discussed in the Diagnosis section for each ofthe two species. In distinguishing between R.quadridentata and R. fusca, the principal char-acter is the degree of excavation of the profemo-ral apical notch. When examining specimens forthis feature, it is important to disregard the ves-titure lining the ventral margin of the femur andto focus on the cuticle.

Key to Species of Adult Nepidae of the UnitedStates and Canada

1. Anterolateral corners of pronotum notwider than head (including eyes); bodycylindrical, long, slender; abdominalsterna not subdivided (Fig. 1); femalesubgenital plate laterally compressed andkeel-like Ranatra F. . . . 4

1'. Anterolateral corners of pronotum widerthan head (including eyes); body flat-tened; abdominal sterna divided longitu-dinally into median and parasternites (su-tures may be indistinct) (Figs. 2,3); femalesubgenital plate broad, flattened 2

2. Length of fifth visible abdominal sternumtwice that of fourth when measured atmidline (Fig. 2); pronotum twice as wideas long (measured at midpoints); body3.5-4.5 times as long (including respira-tory tubes) as wide (measured at widestpoint); eastern United States and south-eastern Canada . . . . Nepa apiculata Uhler

2'. Length of fifth visible abdominal sternumsubequal to that of fourth when measuredat midline (Fig. 3); pronotum % as wideas long; body 5.5-6.5 times as long aswide Curicta S t a l . . . . 3

3. Juga large and bulging, as dorsally ele-

vated as tylus (Fig. 4); Arizona, MexicoCuricta pronotata Kuitert

3'. Juga slightly convex, not as elevated astylus (Fig. 5); Louisiana, Texas, Mexico,Mesoamerica Curicta scorpio Stal

4. Prothorax with midventral hollow groove(Fig. 6); southeastern United States

Ranatra buenoi Hungerford4'. Prothorax without midventral hollow

groove, but may be ventrally flattened orhave paired ventrolateral longitudinal de-pressed lines 5

5. Profemur with midventral narrow, curved,elongate spine, height of spine subequalto width of femur at that point (Fig. 22);male with laterotergites of terminal ab-dominal segment wrapped around sterna(Fig. 19); penultimate antennal segmentwith lateral projection ca. V2 length of ter-minal antennal segment (Fig. 20); Texas,Mexico, Mesoamerica

Ranatra texana Hungerford5'. Profemur with midventral spine at most

slightly longer than wide, usually nolonger than % width of femur at that point(Figs. 7-11); male with laterotergites ofterminal abdominal segment not wrappedaround sterna; penultimate antennal seg-ment with lateral projection variable . . . 6

6. Penultimate antennal segment with lateralprojection absent or <V% length of termi-nal antennal segment (Figs. 12, 13) . . . . 7

6'. Penultimate antennal segment with lateralprojection ^ V2 length of terminal anten-nal segment (Figs. 14, 15) 8

7. Profemur with width of distal portiontwice width of corresponding region oftibia (Fig. 7); penultimate antennal seg-ment with distolateral corner produced orprolonged (Fig. 12); eastern United Statesand southeastern Canada

Ranatra nigra Herrich-Schaeffer7'. Profemur with width of distal portion 3

times width of corresponding region oftibia (Fig. 8); penultimate antennal seg-ment with distolateral corner not pro-duced or prolonged (Fig. 13); easternUnited States and southeastern Canada

Ranatra kirkaldyi Torre Bueno8. Profemur without apical tooth or notch;

may have gradual, shallow concavity (Fig.9); southeastern United States

Ranatra australis Hungerford8'. Profemur with apical tooth, notch, or pro-

nounced concavity (Figs. 10, 11) 99. Body length from tip of tylus to tip of res-

piratory siphons ^45 mm; penultimateantennal segment with lateral projectionsubequal to length of terminal antennalsegment; Arizona

Ranatra montezuma Polhemus9'. Body length from tip of tylus to tip of res-

January 1994 SITES & POLHEMUS: NEPIDAE OF UNITED STATES AND CANADA 31

17

Figs. 1-17. (1) Abdominal sterna of Ranatra. (2) Abdominal sterna of Nepa. (3) Abdominal sterna of Curicta.(4) Head of Curicta pronotata. (5) Head of Curicta scorpio. (6) Prosternal groove of Ranatra buenoi. (7)Prothoracic femur and tibia of Ranatra nigra. (8) Prothoracic femur and tibia of Ranatra kirkaldyi. (9) Prothoracicfemur of Ranatra australis. (10) Prothoracic femur of Ranatra quadridentata. (11) Prothoracic femur of Ranatrafusca. (12) Left antenna of Ranatra nigra. (13) Left antenna of Ranatra kirkaldyi. (14) Left antenna of Ranatrabrevicollis. (15) Left antenna of Ranatra fusca. (16) Sterna of Ranatra quadridentata showing metaxyphus. (17)Sterna of Ranatra fusca showing metaxyphus.

piratory siphons ^50 mm; penultimateantennal segment with lateral projectionV2-V5 length of terminal antennal seg- 10'ment 10

10. Pronotum with anterior portion 3 timeslength of posterior portion when mea-sured at midline; each compound eyeslightly wider than interocular distance; 11.

southeastern seaboardRanatra drakei Hungerford

.Pronotum with anterior portion 1.5-2.5times length of posterior portion whenmeasured at midline; width of each eyesubequal to or less than interocular dis-tance 11

Penultimate antennal segment with lateral

32 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 87, no. 1

projection V2—% length of terminal anten-nal segment when measured from base ofbifurcation (Fig. 14); southern Californianorth to =s40° latitude, Mexico

Ranatra brevicollis Montandon11'. Penultimate antennal segment with lateral

projection 3A-Vs length of terminal anten-nal segment when measured from base ofbifurcation (Fig. 15) 12

12. Profemoral apical notch usually semicircu-lar and ^2 times as wide as deep (Fig.10), distal limit of notch may be poorlydefined; metaxyphus digitate, narrow, ex-tending to posterior margin of hind coxae(Fig. 16); southwestern United States,Mexico, Mesoamerica

Ranatra quadridentata Stal12'. Profemoral apical notch broadly exca-

vated, >2 times as wide as deep (Fig. 11);metaxyphus variable, ranging from asabove to broader, extending to middle ofhind coxae (Fig. 17); widespread acrossnorthern states and southern Canada;northern California south to —36° latitude

Ranatra fusca Palisot de Beauvois

The following is an annotated list of the spe-cies of Nepidae of the United States and Canada.The synonymies list only works that presentimportant taxonomic or nomenclatural informa-tion. Localities listed in Material Examined formost species present new state or provincerecords (i.e., not listed in Polhemus [1988]) orsignificant range information. Because R. texanais redescribed, localities in Material Examinedare reported for all specimens examined re-gardless of range significance. For more generaldistribution information for all species, seethe distribution maps. Abbreviations for collec-tions listed in the Material Examined sectionsare as follows: CAS (California Academy ofSciences), CNC (Canadian National Collec-tion), CSU (Colorado State University), NCSU(North Carolina State University), JTPC (John T.Polhemus Collection), TAM (Texas A&M Uni-versity), UF (University of Florida), UMC(University of Missouri-Columbia), USNM(United States National Museum), USU (UtahState University), WSU (Washington State Uni-versity).

Genus Curicta

Curicta pronotata Kuitert

Curicta pronotata Kuitert, 1949b: 66; Polhe-mus, 1988: 529.

Diagnosis. The slightly larger average size,bulging tylus (Fig. 4), and slender longitudinalcarinae on the last abdominal tergum separatethis species from C. scorpio.

Distribution. This species is an inhabitant ofpools in mountain streams. In the United States,C. pronotata is restricted to Arizona (Fig. 24),where it has been collected only a few times inthe Huachuca Mountains and Sabino Canyonnear Tucson. In Mexico, it is locally common inthe Sierra de los Ajos and Sierra Tarahumara ofSonora and occurs also in western Chihuahua,Sinaloa, Nayarit, and Jalisco (Keffer 1991).

Curicta scorpio Stal

Curicta scorpio Stal, 1862: 203; Keffer, 1993.Nepoidea montandoni Martin, 1898: 68 (syn-

onymized by Champion, 1901: 353).Curicta howardi Montandon, 1910a: 181; Pol-

hemus, 1988: 529 (synonymized by Keffer, 1993).Curicta drakei Hungerford, 1922: 432 (synon-

ymized by Kuitert, 1949b: 68).Diagnosis. The slightly smaller average size,

unswollen tylus (Fig. 5), and prominent longitu-dinal carinae on the last abdominal tergum sep-arate this species from C. pronotata.

Distribution. This species is found in pondsand slow streams in the southern United States;however, it has been collected in rocky hillstream pools in southern Mexico. In the JamesRiver (Mason County, Texas), many specimenshave been taken on the shaded, muddy bankamong grasses completely out of the water(R.W.S., unpublished data). In the United States,C. scorpio occurs in southern Texas and Louisi-ana (Fig. 24), where it sometimes is abundant. InMexico, it occurs in the eastern states of Oaxaca,San Luis Potosi, and Veracruz and extends acrosscentral Mexico in the states of Colima, Morelos,Jalisco, Michoac^n, Nayarit, and Guerrero tooverlap the range of C. pronotata. It occurs inMesoamerica as far south as Guatemala, Hondu-ras, and Nicaragua (Keffer 1991).

Genus Nepa

Nepa apiculata Uhler

Nepa apiculata Uhler, 1862: 12, pi. I, fig. 1;Polhemus, 1988: 530.

Nepa cinerea Ferrari, 1888: 189, in part.Diagnosis. The short, wide habitus, a charac-

teristic of the genus, readily distinguishes N. api-culata from all other North American nepids.

Distribution. This species is found in thenortheastern United States as far west as NorthDakota, Iowa, southwestern Kansas, and Okla-homa, with one isolated record in Georgia (Fig.24). An early instar housed at the USNM is la-beled: Florida: Cape Sable. Because the identityof this specimen is tenuous and the record iswidely disjunct from the remainder of the range,it is considered suspect and requires confirma-tion; therefore, it is not included in the rangepresented here. In Canada, N. apiculata occurs

January 1994 SITES & POLHEMUS: NEPIDAE OF UNITED STATES AND CANADA 33

along the southern border from Quebec as farwest as Manitoba.

Material Examined. North Dakota: RichlandCounty: Mirror Pool, 23-29-VI-66, G. Aarhus,USNM. Missouri: Platte City, 27-IV-36, F. W.Forbes, USNM.

Genus Ranatra

Ranatra australis Hungerford

Ranatra australis Hungerford, 1922: 449;Lansbury, 1974b: 25, figs. 17-18; Polhemus,1988: 530.

Diagnosis. This species is distinguishablefrom similar U.S. and Canadian species by thelack of a distal femoral tooth, coupled with thewell developed penultimate antennal segment,which distinguishes it from R. kirkaldyi and R.nigra. Additionally, the lack of a prominent pros-ternal sulcus distinguishes it from R. buenoi, anda short profemoral median tooth distinguishes itfrom R. texana.

Distribution. Common in the southeasternUnited States (Fig. 25).

Material Examined. Illinois: Jackson County:1 6, Carbondale, farm pond, 8-VIII-87, R. W.Sites, UMC; Union County: 1 9, Pine Hills,2-VIII-84, UMC. Kentucky: Ohio County: RockHouse Slough, 37°28'38" N, 86°53'25" W, JTPC.

Ranatra brevicollis MontandonRanatra brevicollis Montandon, 1910a: 184;

Lansbury, 1974b: 25, fig. 19; Polhemus, 1988:530.

Diagnosis. The penultimate antennal seg-ment has a lateral projection V2 to % the lengthof the terminal antennal segment (Fig. 14),which distinguishes it from R. fusca and R.quadridentata, in each of which the projectionof the penultimate segment is longer. Themetaxyphus usually is long, raised, and keel-like,almost reaching the base of the abdomen;whereas R. fusca usually has a shorter, flattermetaxyphus. The profemoral median spine usu-ally is situated midway between the trochanterand apex (measured on the inner edge). Theprofemoral apical notch usually is defined prox-imally by a rounded angle, without a tooth. Thefemale subgenital plate is slender (in lateralview), and the ventral margin is rounded only inthe basal VA.

Distribution. Baja, California Norte (Mexico)and southern California north to —40° latitude(Fig. 26). This species apparently is adapted to aMediterranean climate, because it is not foundeast of the Sierra Nevada range or north of cen-tral California.

Ranatra buenoi Hungerford

Ranatra buenoi Hungerford, 1922: 442; Polhe-mus, 1988: 530.

Diagnosis. This species is easily distinguish-able from the other North American species bythe very pronounced deep sulcus on the proster-num (Fig. 6).

Distribution. The distribution of this species issimilar to that of R. australis, the southeasternUnited States (Fig. 27).

Material Examined. Illinois: Union County: 18, Pine Hills Recreation Area, 5-V-57, R. Dim-mick, UMC. Kentucky: Butler County: MudRiver, 37°07'24" N, 86°54'03" W, JTPC; CaldwellCounty: Land Branch wetland, 37°20'43" N,87°50'33" W, JTPC; Daviess County: PantherCreek, Old Channel, 37°42'20"N, 87°12'54"W,JTPC; Henderson County: Cypress Slough,37°53'55" N, 87°29'30" W, JTPC; Hopkins Coun-ty: Long Pond, 37°14'08" N, 87°22'20" W, JTPC;Ohio County: Muddy Creek, 37°26'05" N,86°53'10" W, JTPC. Texas: Kaufman County: 18,12.9 km, S Kemp, 15-X-88, B. A. Baugh, UMC.

Ranatra drakei Hungerford

Ranatra drakei Hungerford, 1922: 451; Lans-bury, 1974b: 25, figs. 20-21; Polhemus, 1988:531.

Diagnosis. This species is clearly distinguish-able from the other United States and Canadianspecies by the very long, slender pronotum andlarge eyes; see key.

Distribution. Ranatra drakei is a warm-adapted species restricted to the lower easternseaboard and extreme southeastern states (Fig.26). It is most common in Florida.

Ranatra fusca Palisot de Beauvois

Ranatra fusca Palisot de Beauvois, 1820: 235;Hungerford, 1922: 446; Lansbury, 1974b: 25,figs. 22-23; Polhemus, 1988: 531.

Nepa 4-dentata [sic]: Uhler, 1871: 471 (mis-identification).

Ranatra quadridentata: Uhler, 1876: 338(part) (misidentification).

Ranatra americana Montandon, 1910b: 65(synonymized by Hungerford, 1922: 436).

Ranatra americana edentula Montandon,1910b: 66. New synonymy.

Ranatra fusca edentula: Hungerford, 1922:447; Polhemus, 1988: 531.

Diagnosis. The penultimate antennal segmenthas a lateral projection approximately Ys thelength of the terminal antennal segment (Fig.15). The metasternal process usually is short, ex-tending ~V2 the length of the metacoxal base(Fig. 17). The profemoral median spine usuallyis situated slightly closer to the apex than to thetrochanter (measured on the inner edge). The

34 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 87, no. 1

profemoral apical notch usually is defined prox-imally by a sharp angle (Fig. 11) or tooth. Thefemale subgenital plate is broad (in lateral view),with the ventral margin rounded in the basal V2.The paramere is long, slender, and curved, witha short subapical tooth.

Discussion. Ranatra fusca is the most wide-spread and common North American species.This species usually is an inhabitant of ponds,where it sometimes is common and intermixedwith dead grasses or weeds, although a few spec-imens have been taken from rivers. It is morpho-logically variable over its range, which has cre-ated difficulty in establishing key characteristics.Where the range overlaps that of a closely relatedspecies (in this case R. brevicollis), the variabil-ity is diminished, a phenomenon noticed byJ.T.P. for taxa of distantly related groups (e.g.,Microvelia pulchella Westwood).

The variety edentula was proposed byMontandon (1910b, as americana edentula) forthose populations lacking the preapical tooth onthe profemur and was reported to occur in Penn-sylvania and Texas. Although Pennsylvania iswithin the range of the nominate subspecies,Texas is not, and it is likely that the specimenfrom the latter is R. australis Hungerford. A neo-type has been designated by Polhemus (1994) forR. fusca edentula Montandon, and the type lo-cality has been restricted to Pennsylvania to sta-bilize the nomenclature for the species R. fusca.Specimens with profemora of both forms (i.e.,with and without preapical tooth) and interme-diates are represented in a large sample fromColorado in the JTPC. By definition, subspeciesmust be spatially separated; thus edentula mustfall as a species-group synonym of fusca.

Distribution. Ranatra fusca is found at lowerelevations completely across the northern tier ofcontiguous states in the United States and thesouthern tier of Canadian provinces (Fig. 28). AFlorida record needs reconfirmation. Kuitert(1947) discussed a specimen from Louisiana thatwas placed as this species, but it lacked the distalprofemoral tooth and had a metaxyphus similarin form to that of R. australis; thus it is doubtful.The range of R. fusca does not overlap that of theclosely related R. quadridentata (see Fig. 28).

Material Examined. CANADA: British Colum-bia: Vancouver, Spencer, CAS. Prince EdwardIsland: Watervale, 21-VIII-71, P. Budd, CNC.Nova Scotia: Echo Hwy., 7-11-VIII-71, CNC.UNITED STATES: Colorado: Boulder County:many 66, 9 9, Sawhill Ponds, Boulder, 9-X-84,J. T. Polhemus, JTPC; Douglas County: 1 9,20-111-73, J. T. Polhemus, JTPC; Jefferson Coun-ty: 1 6, 1 9, 21-111-86, J. T. Polhemus, JTPC;Yuma County: 1 6, Chief Creek, nr. Wray, CL2690, 6-VI-92, J. T. Polhemus, JTPC. Idaho: La-tah County: 1 9, Moscow Mountain, 3500-4500ft. [1,070-1,370 m], 21-XI-83, R. W. Sites, UMC;Valley County: Corral Ck., 3 mi. [4.8 km] S Cas-

cade, 23-IX-88, WSU. Kentucky: Nelson County:near Bardstown, JTPC; Perry County: near Haz-ard, JTPC. Montana: Flathead County: Thomp-son River, 6.6 mi. [10.6 km] S Rt. 2, 25-IX-90,WSU; Lincoln County: 1 9, Pipe Ck., 7 mi. [11.3km] N Libby, 24-IX-90, R. S. Zack, UMC; Mis-soula County: Missoula, 21-V-55, WSU. Nebras-ka: Sioux County: 1 6, 1 9, Niobrara River, M.Harris, 16-IX-89, CSU, JTPC. Washington: Ad-ams County: Othello, 10-VII-64, WSU; AsotinCounty: Headgate Pk., 10 mi. [16.1 km] SWAsotin, 26-V-86, WSU; Benton County: Benton,Cedar River, CAS; Chelan County: 2 9 9, 17 mi.[27.4 km] N Leavenworth, T26N R17E sec. 3,16-IX-88, R. S. Zack, UMC; Clark County: 6-IX-39, WSU; King County: 1.3 mi. [2.1 km] E Red-mond, 24-VIII-89, WSU; Columbia County: Bea-ver Lk., 16 mi. [25.7 km] SSW Pomeroy, T9NR41E sec. 2-3, 15-X-87, WSU; Snohomish Coun-ty: Everett, 6-III-43, WSU; Stevens County:Chewelah, Deer Lk., 6-X-72, WSU; ThurstonCounty: Yelm, 22-VI-89, WSU; Whitman Coun-ty: 1 9, Pullman, 21-V-84, R. W. Sites, UMC;Yakima County: Dry Ck., 10 mi. [16.1 km] SWToppenish, 18-VIII-89, WSU. Oregon: HarneyCounty: 1 9, 4-VIII-47, R. C. Erickson, JTPC.Utah: Cache County: Green Canyon, USU; UtahCounty: 1 9, Provo, Bricky Pond, 6-XI-84, D.McClain, NCSU.

Ranatra kirkaldyi Torre Bueno

Ranatra kirkaldyi Torre Bueno, 1905c: 187;Hungerford, 1922: 440; Lansbury, 1974b: 28;Polhemus, 1988: 531.

Ranatra fusca: Montandon, 1910b: 63 (mis-identification).

Ranatra kirkaldyi hoffmanni Hungerford,1922: 442. New synonymy.

Diagnosis. This species is relatively small androbust for the genus, with short respiratory si-phons. The antennal segments are roughly cylin-drical, and the penultimate segment is without adistolateral projection (Fig. 13), which distin-guishes it from all other United States and Cana-dian species of Ranatra. The paramere is long,slender, and curved; the subapical tooth iswidely separated from the apical tooth, and theposterior diverticulum is slender, not expandeddistally. The metaxyphus is truncate, and the lat-eral margins are not membranous.

Discussion. Ranatra kirkaldyi is quite distinctfrom all other North American species in severalrespects and is most closely related to the SouthAmerican fauna (S. L. Keffer, in litt). The strid-ulatory mechanism is lacking, a characteristicshared with only three other American species(see Biology and Ecology section).

The variety hoffmanni was proposed by Hun-gerford (1922) on the basis of slight differencesbetween populations from Minnesota and Kan-sas, particularly the presence or absence of a

January 1994 SITES & POLHEMUS: NEPIDAE OF UNITED STATES AND CANADA 35

preapical tooth on the profemur. Both forms andintermediates are represented in each of twowidely separated samples (Kansas and Missis-sippi) in the JTPC. By definition, subspeciesmust be spatially separated; thus hoffmanni mustfall as a species-group synonym of kirkaldyi.

Distribution. This species has a distributionroughly congruent with the eastern deciduousforests of North America, similar to R. nigra butmore patchy (Fig. 29). Eventually, it probablywill be found in more of the eastern states. It alsois known from Ontario, Canada. In Mississippi,R. kirkaldyi has been found in shallow ponds inhardwood swamps, where specimens werepicked by hand from the submerged brush anddead sticks. This habitat was subject to periodicflooding.

Material Examined. Florida: Marion County:Lake Bryant, 16-IV-38, S. H. Spurr, UF; PutnamCounty: 25-111-69, M. L. May, UF. Mississippi:Jackson County: 2 66,2 9 9, Pascagoula Swampnr. Van Cleave, 14-IX-50; 1 9, same locality,15-XI-50, J. T. Polhemus, JTPC; Sandy Slough, 16, 10-V-51, J. T. Polhemus, JTPC.

Ranatra montezuma Polhemus

Ranatra montezuma Polhemus, 1976: 204;Polhemus, 1988: 531.

Diagnosis. This species is easily distinguish-able from the other North American species byits small size and slender habitus.

Distribution. Ranatra montezuma apparentlyis restricted to Montezuma Well in Arizona (Fig.26), a thermally stable limnocrene occupying acollapsed travertine spring mound.

Ranatra nigra Herrich-Schaeffer

Ranatra nigra Herrich-Schaeffer, 1849: 32;Hungerford, 1922: 444; Lansbury, 1974b: 25,figs. 28-29; Polhemus, 1988: 531.

Ranatra fusca: Uhler, 1876: 338 (misidentifi-cation).

Ranatra protensa Montandon, 1910a: 185(synonymized by Hungerford, 1922: 436).

Diagnosis. This species is distinguishablefrom most other North American species by theshort distolateral production of the penultimateantennal segment (Fig. 12) coupled with the veryslender forelegs that lack a distal femoral tooth(Fig. 7). This species may be distinguished fromR. texana by the very long, spinelike mediantooth on the profemur of the latter.

Distribution. Ranatra nigra has a distributionapproximately congruent with the eastern decid-uous forests of North America (Fig. 30). A femalespecimen housed at WSU is labeled: Arizona:Fredonia, 24-IX-60, F. W. Homing. Because thisrecord is widely disjunct from the remainder ofthe range, we consider it suspect and probably

mislabeled; therefore, it is not included in therange presented here.

Material Examined. Illinois: Jackson County:1 <J, Lake Murphysboro, 30-IX-80, S. D. Fisher,UMC; Williamson County: 1 9, Crab OrchardLk., 13-IX-81, M. Montaba, UMC. Iowa: CerroGordo County: H , 1 9 , Clear Lake, 6-IX-61, J.B. Hervey, TAM; Dickinson County: 1 9, IowaLakeside Lab., ll-VIII-58, F. P. Meyer, TAM;Story County: 1 9, Lake Laverne, Ames, 11-VI-43, J. T. Polhemus, JTPC. Nebraska: DouglasCounty: 1 6, Omaha, 9-VII-52, J. T. Polhemus,JTPC. Kentucky: Crittenden County: PineyCreek, 37°24'09" N, 87°55'07" W, JTPC; HopkinsCounty: Flat Creek wetland, 37°17'30" N,87°24'15" W; McCreary County: nr. Whitey City,JTPC. Missouri: Boone County: 3 6 6, AshlandWildlife Refuge, 12-VII-92, B. J. Nichols, UMC.Texas: Menard County: 13 6 6, 10 9 9, San SabaRiver at Menard, 14-V-90, R. W. Sites, UMC;Kimble County: 1 6, 1 9, South Llano River,TTU Center nr. Junction, l-VIII-86, R. W. Sites,UMC.

Ranatra quadridentata Stal

Ranatra quadridentata Stal, 1862: 204; Hun-gerford, 1922: 452; Lansbury, 1974b: 25, figs.30-31; Menke, 1964: 112; Polhemus, 1988: 532.

Ranatra quadridentata championi Montan-don, 1910b: 65. New synonymy.

Ranatra americana: Van Duzee, 1917: 463(misidentification).

Diagnosis. This species is distinguishablefrom other North American species by thestrongly developed profemoral distal tooth usu-ally followed by a unique deep notch (Fig. 10).Definition of the distal limit of the notch ishighly variable. The notch and the raised, arc-uate, digitate metaxyphus (Fig. 16) distinguishesit from R. fusca, and the long penultimate anten-nal segment distinguishes it from R. brevicollis.

Discussion. The variety championi Montan-don was proposed for specimens from Guatemalathat were slightly larger with a slightly moreelongate anterior part of the pronotum than spec-imens Montandon examined from North Amer-ica. Because varieties proposed before 1960 havestanding as subspecies, they must be treated asspecies-group names. Although specimens fromGuatemala, Honduras, and Nicaragua generallyexhibit differences from North American mate-rial, as Montandon noted, the variation is incon-sistent. In a series from Nicaragua, the variationoverlaps that of a series from Sycamore Canyon,Arizona, and several specimens from the Rio Ba-canuchi, Sonora, Mexico, are of the championivariety. Therefore, the variety is inconsistentlyseparated spatially and must fall as a synonym ofquadridentata.

Distribution. In the United States, R. quadri-dentata occurs from eastern Texas west to south-

36 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 87, no. 1

Figs. 18-23. Ranatra texana: (18) Lateral view of left paramere. (19) Lateral view of terminal abdominalsegment of male. (20) Left antenna. (21) Digitate metaxyphus of metasternum. (22) Median ventral spine ofprofemur. (23) Lateral view of terminal abdominal segment of female.

em California (Fig. 28). In Mexico, it is commonand widespread, known from the states of Chia-pas, Chihuahua, Durango, Guanajuato, Michoa-c£n, Oaxaca, Sinaloa, Sonora, and Veracruz. Itranges southward through Guatemala to Hondu-ras and Nicaragua.

Material Examined. Arizona: Maricopa Coun-ty: 2 6 6, 5 mi. [8 km] SE Wickenburg, 10-IX-80,USU; Yavapai County: 2 6 6, 1 9, In, 5 mi. [8km] NE Castle Hot Springs, CL 312, 7-X-64, J. T.Polhemus, JTPC. New Mexico: Dona Ana Coun-ty: 1 9, Las Cruces, Jornado Exptl. Range, To-bosa Playa, 30-VII-70, C. R. Ward & L. G. Rich-ardson, UMC. Texas: Cherokee County: 5 6 6, 49 9, 10 mi. [16.1 km] N Jacksonville, 15-X-67, T.B. Tennison, TAM; Houston County: 1 9, Crock-ett, 24-X-65, TAM; San Patricio County: 1 6,Lake Corpus Christie St. Pk., 23-V-72, UMC;Smith County: 3 6 6, Bullard, 28-X-67, T. B.Tennison, TAM; Waller County: 2 9 9, 3 mi. [4.8km] W Hempstead, 21-IX-70, R. K. LaVal, UMC.GUATEMALA: 1 9, 10 mi. [16.1 km] N Ascun-cion Mita, CL 1313, 10-1-70, J. T. Polhemus,JTPC. HONDURAS: 1 9, Dept. Comayagua,pond, Quebrada Montanuelos, 1,080 m, 21-111-84, A. R. Gillogly, JTPC. NICARAGUA: 4 <J 6\ 29 9,3 mi. [4.8 km] S Esteli, CL 1309, 8-1-70, J. T.Polhemus, JTPC.

Ranatra texana Hungerford

Ranatra texana Hungerford, 1930: 217; Lans-bury, 1974b: 25, figs. 32-33; Polhemus, 1988:532.

Diagnosis. This species is clearly distinguish-able from the other United States and Canadian

species by the elongated, sickle-shaped mediantooth of the profemur. Superficially, because ofits slender habitus and lack of profemoral distaltooth, R. texana most closely resembles R. nigra,with which it is parapatric, but differs in thelonger penultimate antennal segment and ex-pression of the profemoral median tooth.

Description. Male: (Male described by Hun-gerford [1930]; only additional notes given here.)Paramere long, slender, curved, with short sub-apical tooth (Fig. 18); posterior diverticulum ex-panded; connexiva of abdominal segment VIIembracing operculum distally (Fig. 19).

Female: Body length, 35.30 ± 0.31 mm (mean± SEM; n = 21); respiratory siphon, 18.43 ±0.45; head width, 3.02 ± 0.03. Body slender, cy-lindrical. Overall coloration medium brown tostraw-yellow dorsally, medium to dark brownventrally. Head, pronotum slightly lighter thanhemelytra and respiratory siphons.

Vertex of head elevated above level of eyes;tylus longer, slightly more prominent (dorsallyelevated) than juga. Antenna 3-segmented; pen-ultimate segment with lateral projection ~V%length of terminal segment (Fig. 20).

Anterior part of pronotum —2.3 times length ofposterior part; prothorax —0.23 times length ofbody (excluding siphons). Anterior part impunc-tate, posterior part with dark brown punctation.Scutellum 2.2 times as long as broad. Mediandigitate posterior projection of metasternum(metaxyphus) reaching only middle of hind coxalbase (Fig. 21), acutely raised medially. Profemur= 10.3 mm, with prominent, slender, elongate,sickle-shaped median tooth; median tooth =61%of distance from trochanter to apex of femur;

January 1994 SITES & POLHEMUS: NEPIDAE OF UNITED STATES AND CANADA 37

subequal in height above femur to width of fe-mur at distal side of tooth (Fig. 22). Mesofemuralmost reaching posterior margin of abdominalsternum V. Metafemur reaching middle of ab-dominal sternum VI. Metatibia =1.2 timeslength of metafemur, 9.1 times length of metatar-sus. Tip of hind tarsus reaching % length of res-piratory siphon.

Abdominal connexivum with ventral marginextending posteriorly (Fig. 23), not extendingventrally beneath female subgenital plate as be-neath the male operculum.

Discussion. In male R. texana, the connexi-vum of the last abdominal segment curvesaround the operculum ventrally, a characteristicof the "annulipes" group defined by Drake & DeCarlo (1953). Ranatra texana was not includedby Drake & De Carlo and does not fit comfort-ably in that group, because it lacks some of thegroup's defining characteristics, which are as fol-lows: (1) connexivum of abdominal segment VIIexpanded ventrally only distally; (2) a very high,narrow, and strongly developed metaxyphus inboth sexes; (3) large antennae, with the two dis-tal segments subequal. Finally, R. texana differsfrom all other members of the group, and frommost other New World Ranatra, in lacking astridulatory mechanism (see Biology and Ecol-ogy section).

Distribution. This species has been foundmost commonly in streams from central Texas(Fig. 26) southward through eastern Mexico toGuatemala.

Material Examined. Texas: Gonzales County:2 66,19, Marcos River, Ottine, CL 396, 6-VIII-67, J. T. Polhemus, JTPC; Kimble County: 1 6, 39 9, South Llano River, 2 mi. [3.2 km] S Junc-tion, 14-XII-89, R. W. Sites, UMC; 1 9, SouthLlano River, TTU Center nr. Junction, 10-IV-88,R. W. Sites, UMC; 1 6, same locality, 15-V-88, E.B. Vadder, UMC; 1 6, same locality, 25-V-88, R.W. Sites, UMC; 1 6, same locality, 10-X-88, R.W. Sites, UMC; 1 9, same locality, ll-IX-87, W.R. Perkins, UMC; Menard County: 2 6* 6, 3 9 9,San Saba River at Menard, 4-VIII-88, R. W. Sites,UMC; 3 6 6, 2 9 9, same locality, 14-V-90, R. W.Sites, UMC; 1 9, same locality, 16-VII-89, B. A.Baugh, UMC; Tom Green County: 4 6 6, 1 9,Concho River, Christoval, CL 1113, 9-V-64, J. T.& M. S. Polhemus, JTPC; Wilson County: 7 6 6,2 9 9, Cibolo Ck., Stevens Ranch, Rt. 2, Kosci-usko, 23-111-90, R. D. Stevens, UMC; 3 6 6, 89 9, Cibolo Ck., Stevens Ranch, Rt. 1, 21-VII-90,J. A. Back & R. D. Stevens, UMC. MEXICO:Chiapas: 1 9, Puente La Flor, CL 1247, 19-XII-69, J. T. Polhemus, JTPC. Oaxaca: 1 9, Tehuan-tepec, CL 1067, 30-IV-64, J. T. & M. S. Polhe-mus, JTPC; 1 6, Juchitan, CL 1244, 18-XII-69, J.T. Polhemus, JTPC. Veracruz: 1 6, Potrero delLlano, CL 521, 8-1-71, J. T. & M. S. Polhemus,JTPC; 1 9, Gutierrez Zamora, CL 519, 7-1-71, J.T. & M. S. Polhemus, JTPC. GUATEMALA: 2

6 6, Puerto San Jose, CL 1250, 20-XII-69, J. T.Polhemus, JTPC; 1 9, E of Agua Blanca, CL1304, 10-1-70, J. T. Polhemus, JTPC; 2 6 6, 29 9, Ascuncion Mita, CL 1313, 10-1-70, J. T. Pol-hemus, JTPC.

Distribution

Published state and province records for allspecies of Hemiptera from the United Statesand Canada were collated and presented byHenry & Froeschner (1988) for the first timesince the Van Duzee (1917) catalog. In addition,many regional treatments of aquatic and semi-aquatic Hemiptera (including Nepidae) havebeen presented (Arizona [Blinn & Sanderson1989]; Arkansas [Farris & Harp 1982]; California[Pierce 1948, Usinger 1974, Menke 1979]; Con-necticut [Torre-Bueno 1923]; Florida [Herring1951a]; Idaho [Harris & Shull 1944]; Illinois[Lauck 1959]; Kansas [Oldham 1978, Slater1981]; Louisiana [Penn 1951, Ellis 1952, Gon-soulin 1975]; Mississippi [Penn & Ellis 1949,Wilson 1958, Lago & Testa 1989]; Missouri[Froeschner 1962]; Montana [Roemhild 1976];North and South Carolina [Sanderson 1982];Oklahoma [Schaefer & Drew 1964, 1968;Schaefer 1966], South Dakota [Parshley 1922,Harris 1937]; Texas [Millspaugh 1939]; Virginia[Cross 1972, Bobb 1974]; Wisconsin [Hilsenhoff1984, Cochran et al. 1992]; Alberta, Manitoba,and Saskatchewan [Clark 1926, Brooks & Kelton1967]; British Columbia [Scudder 1977]; andQuebec [Chagnon & Fournier 1948]).

The distribution maps (Figs. 24—30) were con-structed from both published records of occur-rence and range extensions from our records; thelatter are listed in the Material Examined sectionfor each species. In some instances, entire areashave been shaded regardless of whether or not aparticular species has been recorded from everypart of each region included. Although isolatedstate or province records may be nonexistent,these species probably do occur in most of theshaded areas where suitable habitat is found. Amore specific list of records from states, prov-inces, and other regions may be gleaned fromPolhemus (1988) and the regional treatments.

Nepids apparently do not occur north of =51°latitude in Canada and are absent from Hawaii,the southern Great Basin, the Mojave Desert,southern Utah, all of Nevada, northern Arizona,northern New Mexico, and western Colorado.The Great Basin is enclosed by mountains, andmany groups that occur adjacent to or even sur-rounding the Great Basin are not found within it.Bennett (1987) stated that waterscorpions are"not found at high altitudes, essentially notabove 1000 m." The Mojave Desert lies at analtitude of 650 to 1,700 m, and northern Arizonais even higher, as are most of Utah and westernColorado. Altitude may be a factor that prevents

38 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 87, no. 1

Figs. 24-30. Distribution maps of United States and Canadian Nepidae.

R. fusca from invading this range, as the climateis no more severe than in many other places itoccurs. The anomalous presence of R. fusca nearDenver, CO, at —1,700 m, is therefore confound-ing.

Ranatra operculata Kuitert is known from sev-eral localities in Chihuahua and Sonora, Mexico,as close as 200 km to the Arizona border; thus,we expect that this species will eventually befound in the United States. The females are veryeasy to recognize by the extremely long, slendersubgenital plate (operculum) that far surpassesthe base of the respiratory tube; males are similar

to those of R. texana, although the medianprofemoral tooth is much shorter.

Acknowledgments

We thank Thomas J. Henry (U.S. National Museum),Sharon Jasper (Texas A&M University), Steven L. Kef-fer (103 Dinkel Ave., Ridgewater, VA 22812), Frank W.Mead (University of Florida), and Michael Schwartz(Canadian National Collection) for sharing unpub-lished information; and Becky J. Nichols (University ofMissouri) for assistance with preparation of distribu-tion maps. We are indebted to the following for the

January 1994 SITES & POLHEMUS: NEPIDAE OF UNITED STATES AND CANADA 39

loan or gift of material: Dean W. Blinn and Clay Runck(Northern Arizona University), Robert Blinn (NorthCarolina State University), Wilford J. Hanson (UtahState University), Boris C. Kondratieff (Colorado StateUniversity), Carl Olson (University of Arizona), Ed-ward G. Riley and Sharon Jasper (Texas A&M Univer-sity), and Richard S. Zack, Jr. (Washington State Uni-versity). Reviews of the manuscript were graciouslyprovided by Carl W. Schaefer (University of Connect-icut) and J. E. McPherson (Southern Illinois Universi-ty). The Wilbur R. Enns Entomology Museum pro-vided word processing and graphics resources.Funding for R.W.S. was provided in part by project no.PSSL0232. This is Missouri Agricultural ExperimentStation journal series paper no. 11,927.

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Received for publication 24 May 1993; accepted 19July 1993.