Museum of Comparative Zoology





NOV 30 m%

UNIVERSITY OF KANSAS PUBLICATIONS University of Kansas Science Bulletin -Vol. XXXII

November 25, 1948 Lawrence, Kansas



The University of Kansas Science Bulletin (continuation of the Kansas University Quarterly) is issued in parts at irregular inter- vals. Each volume contains from 300 to 600 pages of reading mat- ter, with necessary illustrations. Exchanges with other institutions and learned societies everywhere are solicited. All exchanges should be addressed to the Library of the University of Kansas.

The University of Kansas Science Bulletin, Library of the University of Kansas,

Lawrence, Kan.


The actual date of publication {i. e., mailing date) of many of the volumes of the University of Kansas Science Bulletin differs so markedly from the dates bourne on the covers of the publication or on the covers of the separata that it seems wise to offer a corrected list showing the mailing date. The editor has been unable to verify mailing dates earlier than 1932, Separata were issued at the same time as the whole volume.

Vol. XX— October 1, 1932. Vol. XXI— November 27, 1934. Vol. XXII— November 15, 1935. Vol. XXIII— August 15, 1936. Vol. XXIV— February 16, 1938. Vol. XXV— July 10, 1939. Vol. XXVI— November 27, 1940. Vol. XXVII, Pt. I— Dec. 30, 1941.

Vol. XXVIII, Pt. I— May 15, 1942;

Pt. II— Nov. 12, 1942. Vol. XXIX, Pt. I^July 15, 1943;

Pt. II— Oct. 15, 1943. Vol. XXX, Pt. I— June 12, 1944. Vol. XXX, Pt. II— June 15, 1945. Vol. XXXI, Pt. I— May 1, 1946. Vol. XXXI, Pt. II— Nov. 1, 1947.

Editor Edward H. Taylor

. Editorial Board .

Paul G. Roofe, Chairman Frank E. Hoecker h. b. hungerford Arthur J. Mix

1.1 [' 11 k i; V


(Reprinted from Science Bulletin XI)

Fig. 1. Filaments of Spirogyra before being fed upon by a corixid.

Fig. 2. The same after being fed upon by a corixid. Note the empty fila- ments.

Fig. 3. Sigara (Vertnicorixa) alternata (Say), our most widespread and common North American corixid.

Fig. 4. A highly magnified portion of the Spirogyra shown in figure 2. Note the punctured and empty cells.

Fig. 5. The stomach contents of a small corixid nymph after thirty min- utes of feeding on Spirogyra.

The above illustrations form conclusive proof of the herbiverous tastes of a water boatman. For further evidence on the feeding habits of Corixidae see Hungerford, H. B., in Science Bulletin Vol. XI, pp. 239-249 (1920). Further studies are in progress, indicating that certain species feed also upon mos- quito lan^ae. Dr. R. I. Sailer reports a Calliconxa species in Alaska that is useful in the control of a pest mosquito there.

The color drawings on this plate were made by Miss Ellen Edmonson.




U'f- V









uiuo. CC^^P. ZflOL ySRARY

m 30 19/43



Volume XXXII

University of Kansas Publications

Lawrbnce, November 25, 1948








This paper constitutes a monographic I'evision of the family Corixidae of the Western Hemisphere, inckiding a monograph on the genus Trichocorixa Kirk., by Doctor Reece I. Sailer. Although primarily taxonomic, material is in- cluded on the biology and morphology of the family.

Prior to tliis work some 165 species and 6 subspecies were known from the Western Hemisphere. Forty-four new species, including seven by Sailer*, and six new subspecies, including three by Sailer, are presented in this paper.

Three new subfamilies are established, the Cymatiinae, the Heterocorixinae, and the Stenocorixinae. New tribes set up are the Agraptocorixini, the Glae- nocorisini (for Glnenocori.sa Thorns., and Dasycurixa n. gen.), and the Grap- tocorixini (for Graptocoriza Hungfd., Ncocorixa Hungfd. and Pftcudoghtrno- corisa Jacz.). Two new genera, Cenocorixa and Dtfic/corixa, are described for, respectively, Arctocorixa mileyce Hungfd. and Glacnocorisa hybrida Hungfd. The following subgenera are described in Signrn: Allosigara for Arctocorisa decoralo Abbott; Aphelosigara for Sigara jarmanae Hungerford; Arctosigara for Arctocorixa conocephala Hungerford; Lasiosigara for Notonecta lineata Forster; Pediosigara for Arctocorisa hydatotrephes Kirkaldy; Phaeosigara for Corisa signata Fieber; Pileosigara for Arctocorixa douglasensis Hungerford; and Xenosigara for Arctocorisa ornata Abbott.

The following new species are described: Arctocorisa lawsoni (Colorado); Callicorixa tetoni (Wyoming) ; Cenocorixa andcrsoni (Washington, etc.) ; C kuiterti (California, etc.), and C. sorcnsoni (Utah); Dasycorixa rawsoni (Sas- katchewan) ; Ectcmnostega darivini (Argentina) ; EctemnostcgeUa jamesi (Bo- livia), E. lundbladi (Perii), E. pilosa}ron,s (Peru), E. stridulata (Peru), E. iumidaccphala (Peru), E. venturii (Argentina), and E. woytkoivskii (Peru); Heterocorixa anduzei (Venezuela), H. hintoid (Bolivia). H. jaczcwskii (Brazil), H. lundbladi (Brazil), H. woylkowskii (Peru), and H. wrighti (Brazil); Neo- dgara murilloi (Colombia); Sigara (Tropocorixa) argoitinioisis (Argentina). S. {T.) brazilicnsis (Brazil), S. {T.) cgberta' (Argentina), and S. (T.) robvrti (Brazil); and Sigara (Vermicorixa) cubiensis (Cuba and Porto Rico), S. (V.) ■dejecta (Minnesota, etc.), S. (V.) grossolineata (Michigan, etc.), S. (V.) john- sto7ii (Minnesota), S. (V.) knighti (Michigan), S. (V.) mathesoni (Nova •Scotia, etc.), S. {V .) rnckinstryi (California), »S. (V.) vandykei (California, istc), S. {V.) virginiensis (Virginia, etc.), S. {V.) washingtonensis (Washington, etc.), and Sigara (Pediosigara) depressa. The new subspecies named are Het- erocorixa hesperia venezuelana (Venezuela), Heterocorixa wrighti ollalai (Bra- zil), and Pahnacorixa nana ivalleyi (Kansas, etc.). In addition, Callicorixa noorvikensis Hungerford is reduced to a subspecies of Callicorixa producta (Renter).

Up to and including this paper (exclusive of synonyms) there have been described from the Western Hemisphere 209 species and 12 subspecies. These are distributed as follows: in North America, including Mexico, 137 species and 9 subspecies; in Central America and Insular America, 17 species; and in South America and the Galapogos Islands, 58 species and 3 subspecies.

* See Sai'er's paper on page 289 for a list of the new species, subspecies, and varieties de- scribed by him in Trichucorixa.




Vol. XXXIII November 25, 1948

The Corixidae of the Western Hemisphere


il. B. Hdngerford^ University of Kansas* (Including a monograph on the Trichocorixa by R. I. Sailer)



I. Introduction 7

II. Biology of the Corixidae 8

Habitats * 8

Flight 8

Food 8

Stridulation 10

Mating 12

Oviposition 12

Nymphal life 13

Hibernation 1^

III. Taxonomy of Corixidae 16

The systematic position of the Corixidae 16

Brief history of the taxonomy of Corixidae 18

Generic concepts in Corixidae 26

Identification of Corixidae 36

Technique 36

Glossary 38

Family characteristics of Corixidae 41

Key to subfamilies of Corixidae -13

Diaprepocorinae (not represented in the Americas) Plate IV

Micronectinae (represented by Tenagobia Bergroth) 54

Stenocorixinae (not represented in the Americas) 99

Cymatiinae (represented by Cymatia Flor) 99

Heterocorixinae (represented by Heterocorixa B. White) 105

Corixinae : Key . to tribes 1 37

Glaenocorisini 1 37

Glaenocorisa Thomson. Genotype caw/rcois Thomson 138

* Contribution from the Department of Entomology, University of Kansas, with acknowl- edgments to the University of Michigan Biological Station for opportunity to pursue this study during many summers there.


6 The University Science Bulletin


* Dasycorixa Hungerford. Genotype hybrida (Hungeiford), 142

Graptocorixini 150

Graptocorixa Hungerford. Genotype abdominalis (Say) . . . 156

Neocorixa Hungerford. Genotype snowi Hungerford 150

Pseudoglaenocorisa Jaczewski. Genotype hugo- scotti (Hutchinson) (not found in the Americas),

Plate Vin 53

Agraptocorixini (not represented in the Americas) Plate IV

Corixini contains 20 genera and 13 subgenera 197

IV. Acknowledgments 815

V. Index 819


The identification of American Corixidae has been a difficult and discouraging task for many years. The uniformity of shape, simi- larity of color patterns, the lack of obvious structural characters have always made this family a perplexing one. The early de- scriptions of American corixids dealt largely with color patterns, which are both variable and almost indescribable, and were made by European workers whose types were in European museums or by American workers whose types were not designated. When Doctor Abbott undertook his studies (about 1910) the Uhler material was available in this country but the Fieber species were in European museums and were inadequately known. Abbott's own descrip- tions were based upon such characters as were already in use. At the close of his studies (about 1918) he left two new genera and 17 new species names with their types, some of which were not labeled, and two keys, one to the Corixidae of Georgia, 1913 (Bull. Brooklyn Ent. Soc. VIII, pp. 87-91) including 17 species, and one to the Cor- ixidae in "The Hemiptera of Connecticut," 1923, in which he keyed out four genera and in the genus Arctocorisa placed 11 species, 6 of which were his own. It has since been found that he determined correctly but one of Fieber's species. Doctor Abbott's withdrawal from academic work and the taxonomic study of Corixidae left no one in America willing to identify specimens in this family. Since I was engaged in a study of the biology and ecology of Aquatic Hemiptera, this was a serious matter and I was forced to make my own determinations. Therefore, I undertook to find more precise characters to supplement those in use and then to place the species described by Fieber and others. The latter task made necessary a trip to European museums to examine types. During the j'ears since Abbott's time there have appeared two papers on North American Corixidae containing keys, one of them in Blatchley's Heteroptera of Eastern North America, 1926, which keys out seven genera and brings together the descriptions of some fifty-one species, and the use of which would lead to many misdeterminations. The other by Walley, 1930, keys out twenty species recorded from On- tario and Quebec (Can. Ent. LXII, pp. 285-286). Thus with no comprehensive key available and new species appearing from time to time, some review of the American Corixidae has long been desir- able. It is my hope that this paper may prove useful to those who are interested in the Corixidae of the Americas and make possible the study of the biology and ecology of this interesting and unique familv of water bugs.


8 The University Science Bulletin


For those who find pleasure in collectmg aquatic insects the fol- lowing brief notes on the biology of Corixidae may be interesting.


The Coi^xidae are found for the most parts in i)ools, })onds and lake lagoons where they spend most of their time on the bottom. Some species are found in slowly flowing streams, a few in fast water, and one American species has been taken repeatedly on the bottom of Lake Erie at depths of from fourteen to thirty-five feet ! While the majority live in fresh water, some will inhabit saline or brackish waters. Some species i)refer waters with aquatic vegeta- tion, others more oi)en areas. Some breed only in permanent waters, while others invade the temporary ])ools and i>onds, raise their young and retreat to more stable conditions for the winter.

Flights Corixidae normally possess well-developed flight wings and have been taken at trap lights at night and occasionally recorded in large flights. In flight the hemelytra and metathoracic wings are united by a characteristically Heteropterous device. It is situated at the apex of the under surface of the clavus of the hemelytron and con- sists usually of two parallel, short longitudinal ridges between which enters the turned-up portion of the costal margin of the hind w'ing. In the water, of course, the fragile and membranous flight wings are folded beneath the hemelytra which are buttoned down both along the inner vannal margin and the basal costal margin. In certain genera the flight wings are often reduced and nonfunctional as in Palmacorixa, Krizousacori.va and Cymatia for example.


Corixidae are largely herbivorous. They may forage on the bot- tom, sweeping into the stomach quantities of the organic ooze with its attendant i)opulations, both i>lant and animal, the bulk of the material being of plant origin. In the feeding ]irocess they may ingest, besides the dcsmids, Euglena and other unicellular algae, filaments of Oscillatoria, Zygnema, Mougeotia and Spirogyra. They have been observed to puncture the cells of the larger fila- ments of Spirogyra and suck out the chlorophyll as shown in the colored plate. ^ The ingestion of multicellular organisms and the

1. HunKoifoifl. H. B., 1917, Science N, S. XLV, pp. 336-337; Jl. N. Y. Ent. Soc. XXV, pp. 1-5; 1920 Kansas Univ. Sci. Bull. XI, pp. 234-249. See, also, Sutton, Muriel, 1947 Nature Vol. 160, p. 122.

Western Hemisphere Corixidae 9

packing of the stomach with skeins of filamentous algae is indeed unique amongst the sucking insects of the order Hemiptera. The nature and abundance, oi the lood supply of corixids is one expla- nation of their dominance and gives them an advantage over all other families of aquatic Hemijitera which are uniformly predaceous in their feeding habits. There are indeed some species of Corixidae the palae of which are not flattened and spoon-shaped, and which may still be predaceous. Cymatia americana Hussey, for example, has been reported by Hungerford ^ to show cannibalistic behavior in its first instar. Hale, in his studies on Australian Corixidae,'^ says, "For months I kept in aquaria several species of Corixidae as well as members of Notonectidae and Naucoridae and during that time they were fed only upon larvae of Culex fatigans and Scutomyia notoscripta. Even newly hatched Corixidae were observed to cap- ture tiny mosquito larvae, increasingly large examples being taken during the successive stages of the metamorphosis." Poisson, 1935,'* also reported that the large species of Corixa readily captured lar- vae of Culicidae and Chironomidae and believed that the animal food is even necessary to the females at the time of egg laying. This appears to be the conclusion of Haken Lindberg '' also for Calli- corixa producta and Arctocorisa carinata. We believe, however, that Griffith," 1945, has given a fair analysis of the food gathering behavior and food sources of the average corixid. Since most corixids we have observed foraging upon the flocculent ooze in the bottom of the pool now and then swallow Arcella and other small animals, it is not surprising to see their occasional capture of some small insect. Doctor Sailer observed a species of Trichocorixa feed- ing upon its own eggs. Nevertheless, Corixidae as a group may be looked upon as members of the producing class in the waters where they are found and form a link in the food chain between the "nu- tritious salad'' or organisms in the bottom ooze, and typically pre- daceous forms. Gathering their food from the organic ooze at the bottom of the pool or feeding upon filamentous algae, they in turn make forage for the many predatory animals that lurk in the shad- owy places or dart in pursuit of their prey.

■2. Hungerford, H. B., 1923, Notes on the eggs of Corixidae. Bull. Brooklyn Ento. Soc, XVIIl, No. 1, p. 14.

3. Hale, Herbert M., 1922, Studies in Australian Aquatic Hemiptera, No. 1, Corixidae, Records of the South Australian Museum, Vol. II, No. 2, p. 310.

4. Poisson, R., 193.5, Les Hemipteres aquatiques (Sandaliorrhyncha) de la Faune fran- Caise. Arch, de Zool. Exp. et Gen., I.XXVII. Fasc. 2, p. 480.

5. Lindberg, Haken, 1944.

C. Griffith, Melvin, 1945, Univ. of Kansas Sci. Bull., XXX, Pt. IT, No. 14.

10 The University Science Bulletin


Although stridulation has been known among Corixidae since 1845 when Mrs. R. Ball and Miss M. Ball "' recorded that Corixa striata Curt, was capable of producing two quite different sounds, it was not until 1935 that the way in which the sound is produced was explained by Heinz von Mitis.^ He also was working with Euro- pean species of Corixidae. According to his observations, in the Corixinae neither the strigil nor the palar pegs of the male have anything to do with the soimd production. Only those species in which the males are equipped with a field of pegs on the base of the front femur are capable of producing sound, and the sound is pro- duced b}' rubbing this peg field over the sharp lateral cephalic mar- gin of the head. The tone thereby formed is given resonance by the air chambers in head and prothorax. In the Micronectinae von Mitis observed Micronecta meridionaUs Costa and concluded that the strigil is an essential part of the strong tonal device of these insects.

In our American Corixidae the only published record of sound production is by Hungerford ^ who heard Palmacorixa buenoi Ab- bott chirp in an aquarium one cloudy afternoon. From the struct- ural evidence, the Krizcnisacorixa should be the loudest sound producers among our American water boatmen. The males have re- markably devclojDed peg fields on enlarged anterior femora and a thickened margin on the head which, with the prothorax, is in- flated. American Corixidae which should be capable of sound pro- duction are the males of the following:

Knzousacorixa jemorata (Guerin) Knzousacorixa azleca Jaczewski TrichocorixeUa viexicana (Hungerford) Pa.Jwncorixa gillctlii Abbott Palmacorixa nana Walley Palmacorixa nana walleyi Hungerford* Palmacorixa buenoi Abbott Corisella decolor (Uhler) Corisella tarsalis (Fieber). Corisella tarsascana Jaczewski Corisella hidalgoensis Hungerford* Ectemnostegclla nujniana Lundblad Ectcmnostegella slriduJata Hungerford''' Pseudocorixa conata (Hungerford) Pseudocorixa beameroidea (Hungerford)

7. Ball, Mrs. R.. and Miss M. Ball, lS4ri. Rep. British Asoc. XV, iip. 6i-C,o; 1S46. Ann. Mag. Nat. Hist. XVII, pp. 135-136.

8. Yon Mitis, Heinz, 1935, Zur Biologic der ('(irixiden. Stridulation. Zeitschrift fiir Morphologie und Okologie der Tiere XXX, pp. 479-495.

9. Hungerford, H. B., 1920, The Biology and Ecology of .\quatic and Scmiaquatic He- miptera. ITniv. of Kansas Science Bulletin XI, p. 228.

* New species in this paper.

Western Hemisphere Corixidae 11

Arctocorisa pJanifrons (Kirby) Arctocorisa sutilis (Uhler) Arctocorisa carinata (Sahlberg) Arctocorisa chnnceoe HungcifonI Arctocorisa convexa (Fieber) Arctocorisa lawsoni Hungerford*

Callicorixa vidnerata (Uhler) and possibly others, for C. p^'aeusta

(Fieber) has been heard to stridulate and its stridular area is not


Hesperocorixa escheri (Heer) Hesperocorixa georgiensis (Egbert) Hesperocorixa harrisii (Uhler) Hesperocorixa interrupta (Say) Hesperocorixa lobata (Hungerford) Hesperocorixa lucida (Abbott) Hesperocorixn martini (Hungerford) Hesperocorixa vulgaris (Hungerford) Sigara (.Tropocorixa) chrostowkii Jaczewski Sigara (Tropocorixa) brachypala (Hungerford) Sigara (Tropocorixa) toivnsendi (Hungerford) Sigara (Tropocorixa) czakii Jaczewski Sigara (Tropocorixa) dcnseconscripta (Breddin) **

Sigara (Tropocorixa) deuseconscriptoidea (Hungerford) Sigara (Tropocorixa) dita Jaczewski Sigara (Tropocorixa) forciceps (Spinola) Sigara (Tropocorixa) hosfordcp (Hungerford) Sigara (Tropocorixa) rubyce (Hungerford) Sigara (Tropocorixa) schadei (Hungerford) Sigara (Tropocorixa) santingiensis (Hungerford) Sigara (Tropocorixa) argentiniensis Hungerford* Sigara (Tropocorixa) boliviensis Hungerford Sigara (Tropocorixa) femoridens Hungerford Sigara (Tropocorixa) termasensis (Hungerford) Sigara (Tropocorixa) trimacxdata (LeGuillou) (—jazi (Hungerford) Sigara (Subsigara) jallcnoidea (Hungerford) Sigara (Pilcosigara) douglaserms (Hungerford) Sigara (Phaeosigara) viabropala (Hungerford) Sigara (Phaeosigara) compressoidea (Hungerford) Sigara (Phaeosigara) mackinacensis Hungerford

Sigara (Phaeosigara) zimmermanni (Fieber) (=compitssa (AbboK) Sigara (Phaeosigara) signata (Fieber) Sigara (Phaeosigara) quebecensis (Walley) Sigara (Phaeosigara) mississippiensis Hungerford Sigara (Phaeosigara) bradleyi (Abbott) Sigara (Phaeosigara) sigmoidca (Abbott) Sigara (Phaeosigara) paludata Hungerford Sigara (Phaeosigara) macrocepsoidea Hungerford Sigara (Phaeosigara) dolabra Hungeiford & Sailer Sigara (Vermicorixa) scabra (Abbott) Sigara (Vermicorixa) dejecta Hungerford* Sigara (Vermicorixa) gordita (Abbott) Dasycorixa hybrida (Hungerford) Dasycorixa johanseui (Walley) Dasycorixa rawsoni Hungerford* Cenocorixa imleyce (Hungerford) Cenocorixu. andersoni Hungerford* Cenocorixa expleta (Uhler) Cenocorixa hlaisdeUi (Hungerford)

12 The University Science Bllletin

(Jcnocorixa utaheiisis (Himgerford) denocorixa dakotensis (Hungerford) Ccvucorixa hifida (Hungerford) Ccnocorixa kuiterti Hungerford*

Mating Mating takes place in the water, the male mounting the female and embracing her with his front legs, his usually flattened face closely appressed against her dorsum and his abdomen, if dextral, curved around the left side of the female, if sinistral, around the right side. In cases of reversed asymmetry Doctor Poisson ^^ has found in Corixa afjinis and Sigara sahlbergi that these abnormal males have no trouble mating with their females but do so by di- recting the abdomen to the opposite side from that which is normal. It seems probable that both the palar pegs and the strigil assist the male in a firm clasp of the female during copulation. That these are not essential in all species is indicated by the Callicorixa and some others that lack the strigil, and by Cymatia which lacks both palar pegs and strigil.


We know nothing of the egg laying habits of the subfamilies Diaprepocorinae, Stenocorixinae and Heterocorixinae. Of the Micronectinae the eggs of Micronecta mcridionalis and Micronecta potveri were figured by Poisson, 1938. The eggs of both species are attached horizontally to their support; that of the former is cov- ered with projections, that of M. poweri is not. Neither the shape of the egg nor its method of attachment is like that of the Corixinae. It would be interesting to determine the egg laying habits of the genus Tenagobia which, in the Western Hemisphere, is the counter- part of Micronecta. The eggs of the Cymatiinae and Corixinae are better known. The eggs of these Corixidae are more or less top- shaped and attached to their support by a buttonlike disk.^^ Be- tween the disk and the egg there is a very short stem in most species but in some genera, Cymatia, Agraptocorixa and Krizousaconxa for example, the egg is supported on a stalk of considerable length. The eggs are attached to any available support the water affords and it is not uncommon to find the underside of lily pads and submerged brush solidly covered with them. Their astonishing numbers in the water is more nearly appreciated when we recall that they have been gathered by the Mexicans from reeds submerged for the pur-

3 0. Poisson, R., 193'), Arch. Zool. Exp. et Gen. LXXVII. p. 4Tr>.

11. For striicturc nf corixid PCS'* «<"(' Poisson, lIlS'). .Vicli. Zool. K\|i. I't Gen. "7, Fasc. 2.

Western HexMisphere Corixidae


pose and utilized by them as food. The American genus Rainpho- corixa, wliich inhabits muddy pasture ponds, has the curious habit of phicing its eggs on the carapace of the crayfish.

P^iG. 1. The ¥.ii\i< of Corixidae. (1) Ramphucorirn acuminnta (Uhl.), after H. B. Hiingerford, 1923, Bull. Brookl. Ent. Soc, XVIII, PI. I, fig. 4; (2) Siyara iV ermicorixa) alternata (Say), after H. B. Hungerford, 1917, Jl. N. Y. Ent. Soc, XXV, PI. 9, fig. 1; (3) Krizouf;acorixa jcmurata (G.-M.). after Giierin-- Meneville; (4) Micronectn poiceri (D. & S.), after R. Poi.sjson, 1938, Ann Soc. Ent. Fr.. CVII, text fig. 42; (5) Micronecta merklionalis (Costa), after R. Pois- son, 1938, Ann. Soc. Ent. Fr., CVII. text fig. 14; (6) Sigara (Sigara) striata (L.), after R. Poisson, 1935, Ann. Ent. Soc. Fr., CVII, text fig. XVII A; (7) Agraptocorixa eurynome (Kirk.), after H. H. Hale, 1922, Records of the South Australia Museum, II, No. 2, p. 311, fig. 339 B; (8) Cymatia americana Hus- .sey, after H. B. Hungerford, 1923, Bull. Brookl. Ent. Soc, XVIII, PI. 1, fig. 4.

Nymphal Life Corixidae undergo five nymphal instars as do the majority of aquatic Hemiptera. The wing pads show plainly, beginning with the third instar at which time the spiracles become functional. Scent glands open by paired pores on the caudal margin of the third, fourth and fifth dorsal abdominal segments. In the adult these glands are replaced by a metathoracic gland opening into scent gland orifices laterad of the middle coxae (see plate III). The nymphs have two segmented antennae, one segmented hind tarsi, and the pala and tibia of the front leg is a single segment. There may be one or two generations a year depending upon the species 'or the climate.

14 The University Science Bulletin

PLATE II Life History of a Boatman

(Reprinted from "Life History of a Boatman." by H. B. Hungerford, Jl. N. Y. Ent. Soc.

XXV, No. 2).

Fig. 1. Egg of Sigara (Vermicorixa) alternata (Say).

Fig. 2. Adult of Sigara (V.) alternata (Say).

Fig. 3. Egg of an unknown small corixid.

Fig. 4. First instar nymph of Sigara (V.) alternata (Say).

Fig. 5. Second instar nymph of S. (V.) alternata (Say).

Fig. 6. Tarsus and claws of hind leg of first instar nymph.

Fig. 7. Third instar nymph of S. {V.) alternata (Say).

Fig. 8. Egg shell after nymph has left it.

Fig. 9. Fourth instar nymph of S. (V.) alternata (Say).

Fig. 10. Front leg of late fifth instar nymph, showing tibia and tarsus of adult within the terminal nymphal segment.

Fig. 11. Fifth instar nymph of S. (V.) altcmala (Say).

Fig. 12. The front leg of the male.

Fig. 13. Ventral view of the abdomen of the female.

Fig. 14. Antenna of third instar nymph.

Fig. 15. Antenna of late fifth instar nymph, showing the three distal seg- ments of the adult in the terminal nymphal segment.

Fig. 16. Antenna of the adult.

Fig. 17. Ventral view of the abdomen of a male, showing charact/eristic male asymmetry.

Western Hemisphere Corixidae


16 The University Science Bulletin


Poisson. 1935, says that Micronecta winters in the larval stage, chiefly in the second instar. The majority of the Corixinae winter as adults, although Poisson, 1935. found that Corixa affinis may winter olso in the egg stage and Griffith, 1945.^^ repor^^s some eggs of Fnmvhocorixa acuminata (Uhler) as passing the winter success- fully. T^e species also winter as adults. Hunserford, 1920, found that Palmncorixa buenoi Abbott wintered at Ithaca. N. Y., as fourth instar nymphs. Farther south adults of this species have been t"ken in the winter time. Hussey, 1<^21.^^ found Cvtnatia americana Hus- sey in Minnesota on January 15 under two feet of ice in air bubbles in the ice. Corixids of various species may be taken in midwinter swimming beneath the ice.

TAXONOMY OF CORIXIDAE The Systematic Position of the Corixidae TliH' first corixids described were placed under NotonpctU' in ^^he Hemiptera. Leach, 1817.^ pieced them in his tribe Nntonectides and considered the genera Corixa Geoffrey and Sigora Fabricius as comprising a famdv separate from Notonecta Linn, and Plea Leach. Then Borner. 1904,- proposed to place the Corixklae in a new sub- order, Spndaliorrhyncha. because they are structufallv so diff-^rent from other Hemipterous insects. Reuter, 1912^ reduced Sandalior- rhyncha to series rpnk and proposed Corixoideiie as a superfamily with the sinp'le family Corixidae in it. Oshanm, 1912 •* and Van Duzee. 1917.'' accepted Reuter's proposal but Torre-Bueno. 1917,*' thought that Sandaliorrhyncha sl^ould have ordmal rank. Borner, 1935.^ mad" the followins proposal: "Subordo: Heteroptera. uber- familie: Hydrocorisae (Cryptocerata). Familienreihe: Corixoidea (Sandaliorrhyncha). Familien: Sigaridae, Corixidae." In ano+her paper appearing the same year ^ and apparently written earlier Bor- ner used the same major divisions but in the one family, Corixidae, ]ilaced the "Unterfam. Corixinae" with the genera Cymatia Flor,

12. GriflRth,,M. E., 191.5, Univ. of KRnsas Sci. Bull. XXX, Pt. II, No. 4, p. 27H.

13. Hn.ssey, Roland, 1921, Psyche, XXVIII, p. P3.

1. Leach, William Elford. Brewster's Eclinhg. Encyc. IX, ]>. 124, 1815; Am. cfln. VIII, p. 713, 1832.'

2. Borner, Carl. Zool. An'ieg. XVII, p. 522.

3. Peuter, O. M. Of. Finska Vet. Soc. Forh. LIV, Afd. A. No. 6, pp. 13, 48.

4. Oshanin, B. F. Kat. Palae. Hemip., p. 91.

5. Van Duzee, E. P. Cat. of Hemiptera of America . . . , p. 476. f>. Torre-Bueno, J. R. de la. Ann. Ent. Soc. Am. IX, p. 353.

7. Borner, Carl. Ent. Beihefte aus Berlin-Dah'em 1, pp. 138-144.

8. Biirner, Carl. In Tierwelt Mitteleur, Leipzig 4 i Tiel, 3 Lief. X, pp. 10-lU

Western Hemisphere Corixidae 17

Corixa Geoffr., Callicorixa B. White, and Sigara Fabr. and the "Un- terfam. Micronectinae." It is not clear to me why Doctor Borner used Sigaridae instead of Micronectidae. The proposal of Douglas and Scott, 1865, to make separate families of Corixidae and Sig- aridae was not accepted and Borner's suggestion is not followed by Stichel, 1935, and several other workers since that time. In 1930 Mr. H. P. Jones established the family Micronectidae, and Kirit- shenko, since 1938, has used the families Micronectidae and Corix- idae. Before I agree with Mr. Jones and Doctor Kiritshenko I wish to see the eggs of Tenagobia and Diaprepocoris. The shape of the Micronecta egg is very different from that of the other corixid forms that are known.

The consensus of opinion, however, appears to be that there is only one family, and that this family is sufficiently different from other Hemiptera to be set apart by some higher category. Accord- ing to Mr. China's ^ Heteropterous family tree, the branch bearing the Corixidae and Notonectidae split off from the Heteropterous trunk very early and was itself separated into the notonectid and corixid branches at an ancient date. It seems to me, however, that the branch that gave rise to the Helotrephidae, Pleidae and No- tonectidae should be closer to the Naucoridae than to the Corixidae, and with this idea Mr. China now concurs.

The Corixidae have unique mouthparts and front legs which, with the possession of scent glands on the abdominal dorsum of the nymphs, set them quite apart from other aquatic Hemiptera.

From a study of the genera of Corixidae living today we believe that the ancestral Corixidae had ocelli and a well developed scutel- lum as the Diaprepocorinae still do. In the primitive males prob- ably there was little, if any, abdominal asymmetry and no strigil. The loss of a strigil in Callicorixa, in some Tropocorixa and a few others appears to be secondary.

Since the corixid mouthparts and the modifications of the front legs are intimately related to the feeding habits, it is desirable to decide whether the ancestral form was herbivorous, sucking the chlorophyll from plants, or predaceous upon other animal forms. Tillyard,^" judging from wing remains, traces the Homoptera to the Lower Permian and recognizes no Heteroptera until the Triassic. He says that "comparative morphology indicates that neither of the existing suborders is derived from the other but both from a lost

9. China, W. E. Ann. Mag. Nat. Hist., Ser. 10, Vol. XII, pp. lW-196.

10. Tillyard, R. J. 1926 Amer. Jl. Sci., XI, p. 382.


18 The University Science Bulletin

common ancestor." Since the Homoptera are herbivorous, it seems logical that the primitive Heteroptera were also herbivorous. How- ever, it does not necessarily follow that the first corixids were her- biverous. The wide spread habit of the Corixidae of gathering their food from the fiocculant bottom ooze of their aquatic habitat, with its attendant population of algae and other organisms, may have been a modification from the habit of extracting the chlorophyll from large filamentous algae, to ingesting whole filaments of the finer algae and then to sweeping in the desmids and other organisms in the coze. On the other hand, predaceous forms may have taken to gathering the populations of the bottom material and gaining more and more sustenance from the plant life until some have learned to tap the chlorophyll from filaments too large to ingest. It appears that the long slender pala of Cymatia, Stenocorixa and Diaprepocoris is more primitive than the broad spoon-shaped pala of thoso that gather micro-organisms, in which case the evidence in- dicates that early corixids were predaceous.

Brief History of the Taxonomy of the Corixidae Linnaeus, 1758, described the first corixid under the name No- tonecta striata. Geoffrey, 1762, proposed the generic name Corixa for a large species which he figured but misidentified as A'', striata Linn, which is a smaller species. Fabricius, 1775, proposed the gen- eric name Sigara for N. striata Linn. Illiger, 1807, in a work unfor- tunately long overlooked by Hemipterists, correctly used the name Sigara and identified S. striata (Linn.) as the small species with transverse lines, and showed how it differed in both size and color pattern from Geoffrey's Corixa striata which he renamed C. punc- tata. Leach, 1815, divided his tribe "Notonectides" into two fam- ilies, Notonectida in which he placed Notonecta Linn, and Corixida in which he placed Corixa Geoffrey. He apparently considered Sigara Fabricius a synonym of Cmixu. Then in 1817 t he again divided his tribe "Notonectides" into two families, one containing Notonecta and Plea, and the other S'gara and Corixa. In Sigara he placed Sigara minutissima {=Noton£cta minutissima Linn.), having a distinct scutellum, and in Corixa he placed C. coleoptrata (Fabr.), C. striata'' (Linn.) and added as new C. stagnalis, C. jossarum, C. lateralis, C. dorsalis,'' C. geoffroyi and C. offinis. It is noteworthy

t Leach, W. E. Trans. Linn. Soc. London, XII, Pt. I, pp. 10-18, 1817. I have seen this bibliographic entry dated 1818 but Van Duzee gives it 1817.

* Cliina, 19S8, reports that Doctor Jaczewski examined the Stephens collection in the Brit- ish Museum. Tliis collection was contemporaneous with Leach and if the determinutions apreed wilh Li-acli, C striata Leach = C. sahlbergi Fieber and C. dorsalis Leach S. strtata Linn.

Western Hemisphere Corixidae 19

that he separated the last two from the others by their glabrous hemeltyra and pointed out that C. geoffroyi was the species serving as the type of Corixa Geoffroy.

Fieber, 1851, in his "Species Generis Corisa" gave an historical review of the literature and treated in this paper all of the Corixidae except the very small species with a distinct scutellum which, fol- lowing Leach, he assigned to Sigara. Fieber's Corisa comprised fifty-one species, plus twenty other names of kinds he had not seen but one of which he renamed. It included C. geoffroyi Leach (== C. punctata Illig.), now recognized as the type of Geoffrey's Corixa; C. coleoptrata Fabr., the type of Cymatia; C. praeusta, the type of Callicoiixa; C. hyalinipennis Fabr., now in Agraptocorixa; C. ver- ticalis, the type of Trichocorixa ; C. germarii, now in Arctocorisa; C. kollarii, now in Centrocorisa; and a species which he misnamed C. carinata Sahib, which is a Glaenocorisa.

Thus Fieber's concept of Corixa was a broad one and his "Corisa" has been broken down into many generic and subgeneric groups by subsequent workers.

The name Sigara, however, following Leach, was applied to the very small corixids for many years. Then Kirkaldy, 1897, pro- posed for them the genus name Micronecta with Notonecta minu- tissima Linn, as the genotype and stated that Corixa Geoffroy, 1762, and Sigara Fabricius, 1775, were absolutely identical. Since Kirk- aldy accepted Geoffroy's genera as valid and considered the geno- types the same, he thought he had disposed of Sigai^a. However, Schumacher, 1924, who did not accept the validity of the Geoffroy genera before 1775 again raised the question of "Sigara vs. Corixa" and concluded that Corixa Geoffroy was a synonym of Sigara. In this paper he called attention to Illiger's long-overlooked work of 1807 in which the Corixa figured by Geoffroy was named C. punc- tata and described as twice the size of C. striata and without trans- verse lines on its elytra. Thus C. geoffroyi Leach, 1817, is a syn- onym of C. punctata Illiger, 1807.

It has been our unwavering opinion: first, that Geoffroy's genera in Histoire Abregee des Insectes, 1762, are valid and, second, that C. striata (Linn.) and C. punctata Illiger are not congeneric. We have taken no part in the published discussions of these questions but regret some of the proposals that have been made. It is gratify- ing to see that Mr. China, 1943, in his Introduction to "The Generic Names of British Hemiptera-Heteroptera . . ." recognizes that Opinion 46 of the International Commission validates Geoffroy's

20 The University Science Bulletin

genera of 1762. Mr. China, 1938, plainly pointed out that the geno- types of Sigara and Corixa are not congeneric and that neither of the two genera can ever be synonymous with the other. While in his "Generic Names of British Insects" he tentatively accepted Wal- ton's proposal to place all generic names except those of Glaeno- corisa Thompson, Cymatia Flor and the Micronectinae as subgenera of Corixa Geoffroy, he recognized that such an arrangement might be rejected later. Moreover in "Some Remarks on Walton's Natural Classification of the British Corixidae," 1943, in The Entomologist's Monthly Magazine, Vol. LXXIX, pp. 109-111, Mr. China points out that the relegation of Sigara Fabr. as a subgenus of Corixa Geoffr. by Walton in no way disposed of the question he had discussed in his 1938 paper. Whether as genera or as subgenera the genotype of Corixa is C. punctata Illiger and that of Sigara is C. striata (Linn.).

We maintain that both represent good genera. Even Leach, 1817, without noting the sinistral asymmetry of the males of his C. geof- fr oyi and C. affinis, separated them from the other corixids by their glabrous hemelytra, and Fieber, 1851, on the same character, placed C. geoffroyi Leach and his own C. xanthosoma, C. panzerii, C. atomaria (== C affinis Leach), C. macrocephala (= C. punzeri Fieb.) and C. platycnemis together. Whether Fieber did not try to establish any related groups based upon closer affinities between the different species of Corixidae as stated by Jaczewski or did at- tempt to do so, I do not know. Nevertheless, his interpolated key characters did bring some other related species together also as, for example, C. verticalis, C. pygmaea and C. burmeisterii, now in Trichocorixa, and C. bonsdorfii Sahib, and C. coleoptrata Fabr., now in Cymatia.

Flor, 1860, proposed Cymatia as a subgenus, and Douglas and Scott, 1865, raised it to generic rank. Thomson, 1869, noted that the C. geoffroyi group had the copulatory apparatus directed to the left and proposed for it the subgenus Macrocorisa which must be recognized as a synonym of Corixa. He also proposed the subgenus Glaenocorisa.

Up to this time we find the characters used in the taxonomy of Corixidae were those set forth by Fieber. This author knev; that there is sexual dimorphism of the abdomen and pala, and used the shape of the pala, the facial impressions and their pilosity, the ras- trate or nonrastrate surface of the pronotum and hemelytra, the pilosity of the hemelytra, the shape of the pronotum, with or with- out carina, the shape of the metaxyphus and color pattern. Un-

Western Hemisphere Corixidae 21

doubtedly he gave too great importance to color. Unfortunately the species Fieber studied and figured to show the asymmetry of the male abdomen was his Corisa praeusta which lacks a strigil. As a result it was Buchanan White, 1873, who was the first to dis- cover and describe the strigil in twenty species, to point out that in the males of Macrocorisa Thomson the strigil is on the left side, and that in the C. praeusta Fieber group and in Cymatia there is no strigil. For the C. praeusta group he proposed the name Callicorixa. He also named the genus Oreinocorixa, which is a synonym of Glaenocorisa Thomson. White's study of the strigil was an im- portant contribution to the taxonomy of the Corixidae. Then Kirkaldy (1901-1903) studied and figured the arrangement of the pegs on the male pala of twenty-three species of Corixidae, demon- strating that the number and arrangement of the pegs had specific value. He also figured the pala of Cymatia and of Micronecta and illustrated the field of pegs on the femur of the male of C. geofjroyi Leach. Since then the discoveries of White and Kirkaldy have been used in describing new species of Corixidae. Kirkaldy 's work from 1897 to his untimely death in 1910 had a marked effect on corixid taxonomy. His use of generic names was followed by other workers for a considerable time. He used Corixa Geoffroy for sinistral species; Arctocorisa Wallengren for dextral species with a strigil ; Callicorixa White for dextral species ' without a strigil ; Cymatia Flor, and Glaenocorisa Thomson. He proposed the fol- lowing names for new genera or subgenera: Diaprepocoris 1897, Micronecta 1897, Agraptocorixa 1898, Trichocorixa 1908, and Hes- perocorixa 1908. There were also known in Kirkaldy 's day the fol- lowing: Heterocorixa White, 1879, and Tenagobia Bergroth, 1899. Abbott (1912-1916), in the short time he studiid North American Corixidae, added the genera Ramphocorixa and Palmacorixa and described a total of 17 species, 6 of which are synonyms. He fol- lowed Kirkaldy in using Arctocorixa for most dextral American corixids, but either ignored or overlooked Kirkaldy's proposal to establish as a subgenus of Arctoconsa the name Trichocorixa for the small American species with C. pygmaea Fieb. as genotype (a syn- onym of C. verticalis Fieb.), and used the name Corixa for them in- stead because the males are sinistral. No new structural characters were discovered by him. With Abbott's withdrawal from biological work to become commercial attache in the American embassy in Tokyo, Japan, I found it necessary to undertake the determination of American Corixidae myself. During the winter of 1916-'17 at

22 The University Science Bulletin

the suggestion of H. H. Knight, who was finding the male genitalia of Miridae useful in species fixation, I explored the possibilities of these structures in Corixidae and various other aquatic and semi- aquatic Hemiptera and found them useful. In 1920, in a paper en- titled "The Male Genitalia as Characters of Specific Value in Cer- tain Cryptocerata" which appeared in the University of Kansas Science Bulletin, Volume XI, I stated that I was engaged in pre- paring a monograph of the Corixidae and that drawings of their genital parts would appear later. The paper was presented to call attention to the possibility of using the genitalia of the males of some of the aquatic and semiaquatic Hemiptera, a line of characters not hitherto used, in their taxonomy. In this paper I wrote: "A searching examination of some of the related families has shown some of them to possess quite specifically distinct genital charac- ters. The males of Gelastocoridae, Notonectidae and Corixidae have genital claspers attached to a capsule-like segment which is capable of being withdrawn into the body and thus lies hidden. This strongly chitinized capsule is but loosely attached to the body wall and can therefore be drawn forth and removed from the bug in toto without the least injury or mutilation to the external features of the specimen." Jaczewski, 1921 (and Gajl) in Rozpr. i Wia'd. z Muz. Dzied. Lwow 5/6 1919/1920, pp. 142-150, in discussing the differ- ence between Arctocorisa scotti D. and S. and A. fossarum (Leach), figured the right genital claspers of the males. Lundblad, 1923, in Annales de Biologie Lacustre XII, p. 307, called attention to the