the University of Kansas Science Bulletin volume 51, no. 26. pp. 717-801 June 30, 1980

Cytotaxonomy of the Lygaeidae

( Hemipt era-Het eropt era ) b y N. Ueshima and P.D. Ashlock

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CYTOTAXONOMY OF THE LYGAEIDAE (HEMIPTERA-HETEROPTERA)

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I By i Norihiro Ueshima and Peter D. Ashlock 1 I

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1 Vol. 51, No. 26, pp. 717-801 June 30, 1980 ANNOUNCEMENT

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Vol. 51, No. 26, pp. 717-801 June 30, 1980

Cytotaxonomy of the Lygaeidae 1 (Hemiptera - Heteroptera)

NORIHIRO UESHIMA

Department of Biology, Matsusaka College, Kubo-Cho, Matsusaka-shi, Mie, Japan 515

Peter D. Ashlock

Department of Entomology, University of Kansas, Lawrence, Kansas 66045 CONTENTS

Abstract 717 Lethaeini 757 Introduction - 717 Ozophorini 760 Materials and Methods 720 Antillocorini 760 Cytological Characteristics of the Lygaeidae 721 Targaremini _ 762 Lygaeinae 72 1 Drymini 763 Orsillinae 726 Stygnocorini 765 Metrargini 727 Cleradini 767 Nysiini 732 Myodochini 767 Orsillini 734 Udeocorini 771 Ischnorhynchinae 734 Rhyparochromini 773 Cyminae 737 Megalonotini 777 Cymini 737 Gonianotini 777 Ontiscini 739 Incertae Sedis 779 Ninini 739 Systematic and Cytological Discussion 779 Chauliopinae 739 Holokinetic chromosomes 780 Blissinae 740 Chromosome number 780 Henestarinae 746 Chromosome size 781 Geocorinae 746 The sex chromosome mechanism 783 Oxycareninae 749 The m-chromosome 785 of the sex and Pachygronthinae 75 1 Metaphase position Pachygronthini 75 1 m-chromosome 785 Teracriini 752 Species and subspecies discrimination 787 Heterogastrinae 754 Literature Cited 789 Rhyparochrominae 755 Figures Plinthisini 755 Figures 1-12. Chromosomes of Lygaeinae ....

Abstract

12 subfamilies are discussed. Chromosomal complements of 330 species of Lygaeidae in 131 genera and Chromosome numbers and sizes, sex and m-chromosome characteristics including their metaphase positions, and the use of cytological data in discrimination of higher taxa, species, and subspecies are covered. No cy- of the but several taxa tological element of the Lygaeidae is unique to the family nor to any part family, may be characterized by combinations of cytological features.

Introduction found. Accumulation of data has con- tinued, in Japan by Ueshima, who is re- This survey of the chromosomes of the sponsible for the cytological work and its Lygaeidae was begun early in the 1960s at the University of California, Berkeley, Contribution number 1700 from the Depart- to see information to whether pertinent ment of Entomology, University of Kansas, Law- the classification of the family might be rence, Kansas 66045. 718 The University of Kansas Science Bulletin

interpretation, and in Hawaii and Kansas being the most informative and easiest to collected identified by Ashlock, who and obtain, are used in this study. Those of many of the specimens and has provided one member of each genus studied are the systematic interpretation. The work illustrated. Where significant differences has been furthered several by colleagues were found within a single genus, these who sent specimens from various parts of differences are also illustrated. Illustra- the world. tions include spermatogonial metaphase and I Work on lygaeid chromosomes was be- metaphases and II of meiosis, mostly from a view. gun early in the 1900s in the United States polar Occasionally only a lateral view is by Montgomery (190k, \90U, 1906) and shown because a suitable view was not found in the Wilson (1905a, 1905£, 1909, 1912). The polar prepara- most comprehensive contribution was that tions. Sometimes both lateral and polar views are of Pfaler-Collander (1941), who studied given, and occasionally other of are shown over 50 Finnish species of the family. stages spermatogenesis where these show Other workers in various parts of the stages significant additional information. world each have added a few to bring the total of cytologically known species to The authors would like this survey to about 75. here We add more than 250 spe- be useful to the cytologist and the He- cies to the list. The chromosomes of well miptera systematist alike. The materials over 10% of the 2,800 species listed in and methods section thus includes de- Slater's Catalogue of the Lygaeidae of the scriptions of the process of obtaining and World (1964) have now been studied. preparing chromosomes for study so that Chromosomes of Lygaeidae, like those noncytologists who are so inclined may make their of all Hemiptera (Heteroptera and Ho- own observations. Terms that are not be familiar to the moptera), holokinetic; that is, they may noncytologist have diffuse or holocentric centromeres are defined below. The actual data is pre- rather than localized centromeres as do sented by subfamilies with genera grouped most organisms. Because the centromere alphabetically after a general description of the is distributed along the length of each cytological characteristics of the tribe in the chromosome, the parts of a fragmented appropriate subfamily (or chromosome are not lost and may still large subfamily Rhyparochrominae). A of the and move to the poles at anaphase. Another summary cytological systematic unusual feature found in most Lygaeidae findings concludes the text of the paper. Tables 1 8 chromosome and in some other families of the Heterop- through compare tera is the micro- or m-chromosome. Usu- sizes of species in well-studied genera. 9 ally minute, these chromosomes are al- Table gives the modal number for each of the taxa above the level ways unpaired during meiotic prophase major genus and the of and no chiasmata are formed. During the positions the sex chromosomes first and m-chromosomes I and second anaphase, they are nega- during metaphases and II. Table 10 lists stud- tively heteropycnotic. Generally, m-chro- every species mosomes orient themselves in the center ied to date in the Lygaeidae, the source of the ring of autosomes at metaphase I of information, where the specimens were and often at metaphase II as well, with obtained, and the spermatogonial and the sex chromosomes. The cytogenetic sig- metaphase I and II chromosome comple- nificance of the m-chromosome is un- ments by number. known. Ueshima (1979) has summarized The chromosomes of spermatogenesis, heteropterous cytogenetics. His summary Cytotaxonomy of Lygaeidae 719 includes a detailed description of meiosis are not visible as discrete structures al- the sex chromosomes be dis- in Oncopeltus fasciatus (Dallas) (Lygaei- though may cernible. The diffuse is character- dae, Lygaeinae) as well as discussions of stage istic of the holocentric chromosomes, m-chromosomes, Heteroptera (Fig. 6b). the behavior and mechanism of the sex diplotene—stage during prophase in which chiasmata be evident in each chromosomes, and a list of the diploid and may of chromosomes haploid chromosome numbers of all Het- pair homologous (Fig. studied to date. As it is a 3b). teroptera such, — companion to this contribution, and should equational division the segregation pat- be consulted for further information on tern in which sister chromatids of a chromosome to hemipteran cytogenetics. segregate opposite poles (see reductional). Hemiptera have the usual stages in —chromosomes or chromo- spermatogenesis. A spermatogonial divi- heteropyenotic some regions that stain differently from sion, which is like a typical mitotic divi- the rest of the genome. Positive hetero- sion, is followed by two meiotic divisions. pyenosis refers to darker staining ele- The stages in each division are typical of ments, negative heteropyenosis to lighter animals in general. Interphase is the staining elements. "resting" stage, when the nuclear mem- —chromosomes or chromo- brane is well defined and the chromosomes isopyenotic some regions that stain the same as the are not visible. This is followed by pro- majority of the euchromatin, i.e., are not phase, in which the chromosomes con- heteropyenotic. dense, become visible, and move toward reductional division —the segregation pat- the equatorial plate. At metaphase the tern in which sister chromatids of a chromosomes group on the equatorial chromosome the chromo- a (e.g., paternal plate, the autosomes typically forming some) remain together and proceed to ring around the sex and m-chromosomes. one pole while the chromatids of the In anaphase the chromosomes travel to homologous chromosome (e.g., the ma- the and at the nuclear poles, telophase ternal chromosome) segregate to the membrane becomes visible and the again, other pole (see equational). cell divides in two. In the Heteroptera, the segregation of the autosomes is reduc- Acknowledgments tional (see below) during the first meiot- We would like to the ic division and the segregation of the sex acknowledge great number of specimens sent to us by J. A. chromosome is equational. During the Slater and his (including Merrill H. second division, the autosomes divide group Sweet, Randall T. Schuh, and Samuel Sla- and the sex chromosomes di- equationally in ter), who collected in South Africa 1967- vide reductionally. There is no interphase 68 and who also collected in Florida (with between the first and second meiotic divi- Jane E. Harrington), and in Connecticut. sions in the Heteroptera. Many specimens from Central Africa (Tan- The definitions that follow are of zania) were provided by G. G. E. Scudder. terms that may be less familiar to some Some orsillines and other lygaeids from New readers. Zealand were provided by A. C. Eyles. Ue- shima collected material in Fiji, New Cale- — meiotic dia\inesis stage during prophase donia, and Malaysia while supported by contraction is near in which chromosome U.S. Public Health Grant GM-13197 to R. L. maximum (Fig. 3c). Usinger, and he completed his part of this of Kansas in Law- diffuse stage—stage preceding diplotene work at the University from the Matsu- during prophase in which the autosomes rence, supported by a grant Bulletin 720 The University of Kansas Science

Chromosome saka College. Ashlock collected specimens Squash Technique for Study in California and North Carolina, and dur- for must be in active in Specimens study ing four years at the Bishop Museum or oogenesis. The time Honolulu he collected on all of the major spermatogenesis when this occurs differs from group to islands of Hawaii and for a short period in in Science Foundation In lygaeids and Hemiptera gen- Japan, aided by National group. their full Grants GB-3105 and GB-5860. A U.S.-Japan eral, adults that have just gained resulted in six are the most suitable. Other insects cooperative grant from N.S.F. color and Thailand the last weeks of collecting in Laos by may be at the best stage during Hamil- Ashlock in the same period. Steven nymphal instars or as pupae or teneral and Ashlock have ton, Alex Slater, Virginia adults. Field-collected specimens are killed read the and corrected many errors. or iso- manscript and preserved in either standard be propyl Carnoy's fixative. They may Materials and Methods held for chromosome study in either fixa- herein are un- to About 35 taxa listed tive or they may be transferred 70% sometimes because identified to species, ethyl alcohol. In an emergency, specimens Those from Thai- or they are undescribed. may be preserved in 70%, better, 98% collected Ashlock the fixation and land were by (PDA). isopropyl alcohol, though were collected will be Those from Malaysia by resulting chromosome preparation from South Af- far more Ueshima (MLY). Those less satisfactory. Males are pro- A. Slater and his can the rica were collected by J. ductive for study: only in males G. E. group, those from Tanzania by G. details of sex determination be studied, Scudder (GGES). Some of these speci- and far more sperm than eggs are pro- mens have been lost; all others are in the duced so that the chance of finding di- or in the Mu- collector's collection Bishop viding cells is greater. those of Ueshima, seum, Honolulu, except Standard technique.— \. Dissect out the are with Ashlock. These which specimens testes or ovaries in fixative. In small speci- are identified with a code number, the mens, gonads may be dissected out after collector or both. those code, Hopefully the whole specimen is fixed. 2. Fix testes extant with code numbers can Car- specimens or ovaries in isopropyl or standard be identified and /or named in the future. 24 hours or more. 3. noy's fixative for Specimens used in this study were Place in acetocarmine stain for about 24 mostly field collected, preserved in isopro- hours. 4. Remove gonads from stain and fixative or slide. Add a few pyl Carnoy's (Ueshima, 1963) place on a glass drops and standard Carnoy's fixative, and prepared of stain and apply a coverslip. 5. Tap the standard or tech- with be- with quick squash press lightly on coverslip forceps, made with it. Place a nique. All observations were ing careful not to move piece and the aid of a camera lucida and photo- of filter paper over the coverslip press with a 35-mm camera. to graphs were taken gently with fingers squash specimen, indicated a to move the cover- Magnifications are by 10-/mi again being careful not scale on each excess stain. The drawing. slip. Blot up prepara- tion is now for If overstained, The above description is sufficient for ready study. with acetic acid. 6. To make those familiar with cytological techniques, destain 45% last for several months, but since hopefully this paper will be used the preparation of the with a by workers with little or no cytological seal the edges coverslip paraf- insect fin-balsam mixture. To make the prepara- training who may wish to study freeze it for about 10 min- chromosomes, the following instructions tion permanent, few seconds are included. utes using dry ice, or for a Cytotaxonomy of Lygaeidae 721 with liquid nitrogen. Then very quickly ture: 1 part paraffin (60° C or higher remove the coverslip with a sharp razor melting point) to 1 part balsam (as pre- blade, air dry the slide for 1 minute, add pared to mount tissues). Boil together for about 20 Euparol, and replace the coverslip. minutes and allow to solidify. — The mixture can be with a heated Ouicf{ technique. This method is applied much faster, but it does not yield as good spatula. a and is much less preparation satisfactory Cytological Characteristics of for 1. As in stand- obtaining photographs. the Lygaeidae ard technique. 2. Fix testes or ovaries in isopropyl or standard Carnoy's fixative for Lygaeinae 15 minutes. 3. Place on slide gonads glass The chromosome cytology of 12 gen- and add a few of acetocarmine stain. drops era and 26 species of the subfamily Ly- slide under a desk and Warm gently lamp gaeinae has been studied. The great ma- as the stain add evaporates more, taking jority have 14 (12 + XY) chromosomes, the does not become care that specimen only one genus, Oncopeltus, diverging 4. Blot dry. Continue for 15 minutes. up much from that number. Therefore, it is as much stain as possible from around safe to assume that the modal number for with filter wash with specimen paper, the subfamily is 14 (12 + XY). The gen- more stain, and blot again. 5. As in stand- era Lygaeus and Oncopeltus each have ard 6. As in standard tech- technique. one species (L. simlus and O. famelicus) nique. with 22 + This — (20 XY). unusually high Reagents for chromosome study. 1. number may be derived either by simple Isopropyl Carnoy's fixative: 1 part glacial fragmentation of some chromosomes as in acetic acid to 3 parts isopropyl alcohol, the genus Thyanta (Schrader and Hughes- or auton- 98% to pure. This fixative may be kept Schrader, 1956) by chromosome for more than three months without losing omy as in Banasa (Schrader and Hughes- its effectiveness. 2. Carnoy's fixative Schrader, 1958). 3 (standard) : 1 part glacial acetic acid to A characteristic of the subfamily is the parts ethyl alcohol, 95%. This fixative may lack of an m-chromosome. This situation be used in place of the isopropyl Carnoy's, is found elsewhere only in the Oxycareni- feel that it must be but many cytologists nae and a few genera of the Rhyparochro- used within two days after mixing. 3. minae. The behavior of sex chromosomes 1 basic Acetocarmine stain. Dissolve gram during meiosis in this subfamily is quite 100 acetic acid. Boil carmine into ml 45% orthodox in Heteroptera. At metaphase but not 20 to 30 minutes, do evaporate. I and II, the X and Y chromosomes lie in over Use of a condenser placed vertically the center of a ring formed by the auto- the boiling flask is recommended. Filter. somes. Figure 132 shows the distribution stain is Aceto-orcein preferred by many, pattern of the chromosome complement in orcein be used. One but pure must gram this subfamily. orcein is dissolved in 100 ml acetic — 45% 1. Arocatus rusticus (Stal). The male acid and allowed to stand for 3 to 4 days. diploid chromosome complement in Aro- Filter. 4. Acetocarmine stain (modified catus rusticus consists of six pairs of auto- for To about 10 ml of quick technique). somes and an XY sex pair. All the chro- acetocarmine stain add 4 or 5 of drops mosomes except the Y are medium-sized ferric acetate saturated in acid. propionic (Fig. la). The Y chromosome is about Let the stain mixture stand for at least 1 half as large as the others and so is easily hour before use. 5. Paraffin-balsam mix- distinguished. 722 The University of Kansas Science Bulletin Cytotaxonomy of Lygaeidae 723

the to one The male meiosis of this species is anaphase, Xi and X2 go pole The sex while the Y moves to the other. typical of Heteroptera in general. — chromosomes, X and Y, are positively 3. Graptostethus manillensis (Stal). the heteropycnotic in early prophase. In The male chromosome complement of diffuse stage, the X and Y tend to undergo Graptostethus manillensis is six pairs of which seems nonhomologous association, autosomes plus an XY pair (Fig. 3a). diakinesis. to persist into early Rapidly Two pairs of autosomes are somewhat tetrad nature oi after the diffuse stage, the larger than the other four pairs. The X the six bivalents reappears, the bivalents chromosome is the same size as the small- are usually characterized by one chaisma, er autosomes and indistinguishable from and they pass into a typical diakinesis. By them, while the Y is the smallest com- from late diakinesis, the X and Y separate ponent in the chromosome set and easily and can each other, become isopycnotic, distinguished. as double structures be resolved composed The course of meiosis is the same as of two sister chromatids. The terminaliza- in Arocatus rusticus. By diakinesis, the X tion of chiasmata is the first completed by and Y are both positively heteropycnotic. At the first six metaphase. metaphase, In the diffuse stage, the X and Y come autosomal bivalents have oriented on the close together and remain so to the late of a hollow while the In dia- periphery spindle, diplotene stage (Fig. 3b). early and Y univalents lie side X invariably by kinesis the X and Y separate from each side and the center of the occupy spindle other and may already be seen as double formed the autosomes lb). The by (Fig. structures (Fig. 3c). With continued con- meiosis is reductional for first division of traction of six autosomal tetrads (biva- the autosomes and for the sex in equational lents), the X and Y become isopycnotic As is usual in chromosomes. Heteroptera, late diakinesis. By the prometaphase, the from the second meiosis follows directly terminalization of chiasmata on each auto-

I without At telophase any interphase. some is completed. the autosomes the second metaphase, again tetrads At metaphase I, six autosomal lie on the form a hollow spindle and pe- the form a hollow spindle and lie on and riphery while the X Y again occupy while the X and periphery of the spindle the the center of a spindle and undergo Y lie in the center (Fig. 3d). During ana- "touch and characteristic go" pairing (Fig. divide phase I, the X and Y equationally. the X and Y lc). During anaphase II, lie At metaphase II, the autosomes again the autosome to opposite poles with the X pass on the periphery of a spindle and haves. — and Y occupy the center of the spindle 2. Arocatus suboeneus Montandon. with the characteristic "touch and go" The chromosome number of Arocatus sub- In the X pairing (Fig. 3e). anaphase II, oeneus is 15 in the male, consist- with the diploid and Y separate to opposite poles of 12 autosomes and X1X2Y sex chro- ing autosomes (Fig. 3f). mosomes 2a). All autosomes are — (Fig. 4. Lvgaeospilus tnpunctatus (Dallas). similar in size and the Xi is as as large The chromosome complement of Lvgaeo- and Y are less the autosomes. The X2 six of autosomes spilus tripunctatus is pairs than half the size of the autosomes. Be- of the six of and an XY pair. Two pairs are the same are the cause they size, they autosomes are slightly larger than another. indistinguishable from one others and the Y is the smallest component is while the X to the The course of meiosis (Fig. 2b, c) in the set, belongs in size and cannot be the same as in A. rusticus. In the second intermediate group 724 The University of Kansas Science Bulletin distinguished from the autosomes (Fig. species. The X and Y divide equationally 4a). The meiotic process of this species in the first division (Fig. 7c). (Fig. 4b, c) is the same as in the foregoing 8. Neacoryphus bicrucis (Say) and N. in rubicollis —The species every respect. — (Uhler). diploid chromo- 5. Lygaeits kalmii Stal. The diploid some complement of Neacoryphus bicrucis of of metaphase Lygaeus kalmii consists and N. rubicollis consists of six pairs of six pairs of autosomes and an XY pair. autosomes and an XY sex chromosome The X and Y are not conspicuous since pair (Fig. 8a). One of the chromosomes in they are similar to the autosomes in size. the set, presumably the Y, is smaller than However, one chromosome, presumably the others and easily recognized. The the Y, is slightly smaller than the rest of meiotic process of these species (Fig. 8b, the is chromosomes (Fig. 5a). The course c) the same as in preceding species. of meiosis 5b, is the same as in (Fig. c) 9. Ochrimnus tripligatus (Barber).— described species previously. The diploid chromosome complement of 6. Melanopleurus bistriangirfaris (Say) Ochrimnus tripligatus consists of six pairs and M. of autosomes and an XY sex — pyrrhopterus melanopleurus (Uh- pair (Fig. ler). The male diploid chromosome 9a). In this species the sex chromosomes complement of both Melanopleurus bistri- are easily distinguished from the auto- angirfaris and M. pyrrhopterus melano- somes because of their smaller size. One pleurus is six pairs of autosomes and an of these sex chromosomes, presumably the XY sex chromosome pair (Fig. 6a). In Y, is only about half the size of the X. the spermatogonial metaphase of both spe- The course of meiosis of the species (Fig. cies, the X and Y are not easily distin- 9b, c) is. like those described previously in guished from the autosomes, since all the every respect. chromosomes are similar in size. — 10. Oncopeltus famelicus (Fabricius). The course of meiosis in these two The spermatogonial metaphase plate of species is the same as in other species Oncopeltus famelicus consists of ten pairs previously described. However, in the of autosomes and an XY sex chromosome diffuse stage of M. bistriangirfaris, posi- pair (Fig. 10a). The X and Y are indis- tively heteropycnotic X and Y chromo- tinguishable from the autosomes because somes have separated from each other all chromosomes are similar in size. The (Fig. 6b) and clearly show the double na- course of meiosis of the species is quite ture of sister chromatids. This double orthodox (Fig. 10b, c), unaffected by the nature at the diffuse stage is not conspicu- large number of chromosomes. Of course, ous in other species. The first and second the X and Y are equational at the first metaphases also proceed as in previously division. described — species (Fig. 6c, d). 11. Oncopeltus fasciatus (Dallas). The 7. Melanostethus marginatus (Thun- details of the spermatogenesis of Oncopel- berg).—The spermatogonial metaphase of tus fasciatus have been described by Mont- Melanostethus marginatus consists of six gomery (1901£, 1906) and Wolfe and John pairs of autosomes and an XY pair (Fig. (1965). Our findings for this species con- 7a). One pair of autosomes is smaller firm their observations of the chromosome than the others, the X is similar to the cytology. small autosomes in and the Y is the size, The chromosome complement of the smallest in the set. component male diploid set of this species is seven The course of meiosis in the species pairs of autosomes plus an XY sex pair (Fig. 7b, d) is as in previously described (Fig. 11a). All the chromosomes are simi- Cytotaxonomy of Lygaeidae 725

Lygaeinae

- . &- * -s &&&$&$ • b H d .i.W*V' "1 &gM*i$%tik ttlt ini;ti

6 Melanopleurus bistriangularis

a » • • it I t I I 7 Melanostethus marginatus

a 1 ••V V'i t • 8 Neacoryphus bicrucis

a » *2> Oil' »l »v 9 Ochrimnus tripligatus

• a t 'I

t 1 10 Oncopeltus famelicus 1

a • • t • • • J

Oncopeltus fasciatus

a • b *J&* I ? M.Hil

12 Spilostethus ho spes

Fig. 6-12. Chromosomes of named species of Lygaeinae: a, spermatogonia! metaphase; b, first metaphase; c, second metaphase. (Exceptions Fig. 6: b, diffuse stage; c, first metaphase; d, second metaphase. Fig. 7: c, first anaphase; d, second metaphase.) Scale = 10 /*m. 726 The University of Kansas Science Bulletin

lar in size. The course of meiosis (Fig. because of the holokinetic nature of he- lib, c) is as in previously described species. mipterous chromosomes (Schrader and 12. Spilostethus hospes (Fabricius), S. Hughes-Schrader, 1956, 1958). jurculus— (H.-Schaeffer), and S. macilentus In the Orsillini, two genera and six (Stal). The spermatogonia! metaphase species have been worked out. The genus plates of Spilostethus hospes, S. jurculus, Hudsona has 14 (12 + XY) chromosomes and S. macilentus consist of six pairs of (Eyles, pers. comm., informs us that this autosomes and an XY sex pair (Fig. 12a). genus may belong to the Nysiini, how- One pair of autosomes is slightly larger ever), but the genus Ortholomus shows than the others. The spermatogenesis of two chromosome types: 14 (12 + XY) S. hospes (as Lygaeus hospes) has been and 16 (14 + XY)'. All Ortholomus spe- studied by Manna (1951). Our observa- cies always have one pair of extremely in tions of this species confirm his every large autosomes (see Fig. 132h, i). How- feature. The course of meiosis in these ever, the 14-chromosome species also have three species (Fig. 12b, c) is the same as a pair of large autosomes that are interme- in others previously described. diate in size between the extremely large and medium autosomes. Such an inter-

Orsillinae mediate-sized autosome pair does not oc- cur in the species with 16 chromosomes. In the orsilline tribe Metrargini, seven Therefore it can be assumed that the 16 genera and 31 species are now known chromosomes are derived from 14 by the cytologically. All genera except Darwin- fracture of the intermediate large pairs of ysius present 16 (14 + XY) chromosomes. autosomes. The modal number of the Darwinysius shows 14 (12 + XY) instead tribe is assumed to be 14 (12 + XY). of 16. In the genus Neseis, specimens of The ancestral stock of the N. hiloensis approximatus collected from subfamily Orsillinae have had 14 West Maui, Hawaii, had 18 (16 + XY) may (12 + XY) instead of the 16 found in the one other chromosomes for the following reasons. All with 14 and the collection of this species. This 18-chro- species chromosomes, Ortholomus with 16 mosome form is definitely derived from species chromosomes, show one the 16-chromosome form either by dupli- invariably extremely large pair of autosomes. In the all the cation or by fragmentation of one pair of Metrargini, with 16 chromosomes have no such autosomes (see Fig. 132c, d). The modal species autosomes and Darwin- number of the tribe is 16 (14 + XY). extremely large ysius species, which show 14 chromosomes In the Nysiini, four genera and 28 and are a primitive genus in the tribe, species have been cytologically studied. All have a pair of extremely large autosomes. species except Nysius tenellus show 14 Therefore, the 16-chromosome state in the (12 + XY) chromosomes. There is no seems to be derived from the doubt that the modal number of the tribe Metrargini 14-chromosome stock by the fracture of is 14 (12 + XY). All the species with 14 one pair of extremely large autosomes. All chromosomes always have one pair of species in the Nysiini except Nysius tenel- extremely large autosomes. This is char- lus have a pair of such extremely large acteristic of the tribe. One of the 21 spe- autosomes and have 14 chromosomes. cies of Nysius examined, N. tenellus, has The distributional of the chro- 22 (20 + XY) chromosomes instead ot pattern 14 mosome in the Orsillinae and (see Fig. 132e, f). This high chromo- complement some number may be caused by fragmen- comparative size difference of chromo- tation or chromosome autonomy, possibly somes in various groups in the Orsillinae Cytotaxonomy of Lygaeidae 727 are shown in Figures 131 and 133. ing prophase and there is no evidence for Other characteristics of chromosome crossing-over between them. At prometa- cytology in the Orsillinae are the presence phase, the m-chromosomes come close to- of a pair of m-chromosomes and the cen- gether and at metaphase they are momen- tral position of the X, Y, and m-chromo- tarily co-oriented at the center of a hollow some at metaphase I. At metaphase II, spindle (Fig. 13b). The m-chromosomes the XV pseudopair and the m again take are negatively heteropycnotic at meta- a central position in Metrargini. However, phase I and they maintain this condition of in species of the Nysiini and Orsillini, the until the completion meiosis. XY lies in the center and the m-chromo- At metaphase I, five autosomal biva- to locate on the with some tends periphery lents have oriented on the periphery of a the autosomes (see Figs. 13-27). spindle while the X and Y univalents and the m-chromosome lie side by side and Metrargini. invariably occupy the center (Fig. 13b). The first meiosis is for the sex 13. Darwinysius marginalis (Dallas) equational and D. wenmanensis Ashlock.—Darwin- chromosomes but is reductional for the autosomes and the m-chromosome. The ysius marginalis and D. wenmanensis have the same chromosomal constitution. The second metaphase follows directly upon of the first division without male diploid chromosome complements of completion At II, the these species consist of five pairs of auto- any resting period. metaphase autosomes lie on the of a somes, a pair of m-chromosomes, and an again periphery while the XY and the XY sex pair (Fig. 131a). One autosome spindle pseudopair m-chromosome lie side side and oc- pair is very much larger than the others by the center of the spindle (Fig. 13c). and is easily recognized. The pair of m- cupy The m-chromosome is hetero- chromosomes is the smallest component in negatively the second meiosis. As a the set and is about half the size of the pycnotic during result of the second division there are two Y chromosome. The X chromosome is of one five about the same size as the medium-sized kinds spermatids: containing an and the X, autosomes and the Y is about half the autosomes, m-chromosome, five an size of the X. and another containing autosomes, m-chromosome, and the Y. During meiosis, the X and Y chromo- 14. hylaeus (Kirkaldy), somes are positively heteropycnotic in the Glvptonysiits G. amicola Ashlock, and Glyptonysius sp. early prophase and undergo nonhomolo- from West Maui, Hawaii.—These three gous association. This status of the sex will be described to- chromosomes seems to persist into the Glyptonysius species since they are the same in essential diplotene stage. Immediately after the dif- gether chromosome cytology. The spermatogonial fuse stage, autosomes become evident, and consists of six of auto- the X and Y are already double structures metaphase pairs a of the m-chromosomes, and composed of sister chromatids. In late somes, pair an XY sex 14a). One of the diakinesis, the X and Y become isopyc- pair (Fig. six of autosomes is larger notic, but they can be distinguished from pairs slightly than the others. The m-chromosomes are the autosomes because they are composed In G. of two instead of four chromatids, as are the smallest component in the set. autosomal bivalents. Terminalization of amicola, the X chromosome is a little chiasmata on the autosome pair is com- smaller than the small-sized chromosomes, pleted by the prometaphase. the Y is about half as large as the X, and The m-chromosomes are unpaired dur- the m-chromosomes are about half as 728 The University of Kansas Science Bulletin

Orsillinae a b jM s METRARGINI c ii {»»•.•»• & m

10 Darwinysius marginalis

H Glyptonysius hylaeus

a b ,#«. _• • ••• iiftiiii #v yrt ••?•• ..% ;v

15 Metrarga elinguis

a I t b •••• ••••# 1 ?•'•• I V I *#•• V. 16 Neseis kirkaldyi

«. a fit b ••• Aft '-»» * • ••'• 17 Neseis hiloensis - from W. Maui

MS a f I f *.; i

18 Nesoelimacias contracta

Fig. 13-18. Chromosomes of named species of Orsillinae: a, spermatogonial metaphase; b, first metaphase; c, second metaphase. {Exception Fig. 15: d, second anaphase.) Scale = 10 /*m. Cytotaxonomy of Lygaeidae 729 large as the Y. In G. hylaeus, the X is er; N. jasciata convergens Usinger; N. ful- two-thirds as large as the small-sized auto- gida Usinger; N. hiloensis approximata somes and about twice as large as the Y, Usinger, from East Maui, Hawaii; N. h. and the m-chromosomes are about half as hiloensis (Perkins); N. h. interoculata h. large as the Y (see Fig. 14a). In Glypto- Usinger; N. jugata Usinger; N. sp. near from is N. N. nysius sp. West Maui, the X only hiloensis; /{irl^aldyi (Usinger) ; leg- slightly smaller than the small-sized auto- nota Ashlock; N. nitida consummata somes, the Y is half the size of the X and Usinger; N. n. impressicolis Usinger; N. the m-chromosome is a little smaller than n. insulicola (Kirkaldy); N. n. nitida (B.- theY. White); N. ochriasis baldwini Usinger; The course of meiosis of these three N. o. maculiceps Usinger; N. o. ochriasis N. N. species (Fig. 14b, c) is the same as in (Kirkaldy); pallassata Ashlock; N. saundersiana Darwinysius marginalis. The X and Y are pallida Usinger; (Kirk- and N. silvestrts The positively heteropycnotic in early prophase aldy); (Kirkaldy). male chromosome of and become isopycnotic by the prometa- diploid complement these consists of six of auto- phase. The m-chromosomes are unpaired species pairs somes, a of and an during the prophase and negatively hetero- pair m-chromosomes, XY sex as shown in 16a. pycnotic at the first metaphase. The pair, Figure differences in chromosome separation of the first meiosis is reduc- Comparative tional for the autosomes and the m-chro- components are listed in Table 1. mosome and equational for the sex chro- The meiotic process of these species is mosomes. as in Darwinysius marginalis. Therefore, — the course of meiosis is described N. 15. Metrarga elingitis Ashlock. The using as an 16b, The diploid chromosome complement of Me- kjrkaldy example (Fig. c). X and Y are in trarga elingitis is six pairs of autosomes, positively heteropycnotic the and a pair of m-chromosomes, and an XY early prophase nonhomologously associated at the diffuse late dia- sex pair (Fig. 15a). One pair of auto- stage. By somes is a little smaller than the others. kinesis the X and Y become isopycnotic. first division is reductional for the The X chromosome is a little smaller than The for sex the small-sized autosomes, and the Y is m-chromosome and equational the about two-thirds as large as the X. The chromosomes. m-chromosomes are about two-thirds as 17. Neseis hiloensis approximata Using- as the Y. — large er from West Maui, Hawaii. The speci- The course of meiosis in this species mens originally identified as Neseis hilo- is the same as in Darwin- (Fig. 15b, c) ensis approximata from West Maui have a The X and Y are ysius marginalis. posi- different chromosome complement from tively heteropycnotic in the early prophase others of the genus. The diploid chromo- and become isopycnotic by late diakinesis. some complement is seven pairs of auto- The m-chromosome is unpaired during somes, a pair of m-chromosomes, and an the prophase and negatively heteropycnotic XY sex pair (Fig. 17a). One pair of auto- at metaphase I. The m-chromosome is, somes is smaller than the others. The X again, negatively heteropycnotic during is the same size as the smaller autosomes, the second division (Fig. 15c, d). the Y is about half as large as the X, and 16. Neseis hjrhaldyi (Usinger) and — the m-chromosome is a little smaller than other Neseis spp. The chromosome cy- the Y. The course of meiosis of the tology of the following species is the same speci- in essential features: Neseis ehinai Using- mens (Fig. 17b, c) is essentially the same 730 The University of Kansas Science Bulletin as in Darwinysius marginalis and in other Ashlock, O. fosbergi Usinger, O. gressitti species of Neseis. Ashlock, O. montivagus (Kirkaldy), 0. These specimens may represent a sibling nimbatus (Kirkaldy), O. centralis Usinger, species of N. hiloensis, but further study and O. yoshimotoi Ashlock. The diploid is needed to clarify the situation. See fur- chromosome complement of these species ther comments in the discussion section. consists of six pairs of autosomes, an m- 18. Nesoclimacias contractu chromosome and the XY sex — (Black- pair, pair burn). The spermatogonial metaphase of (Fig. 19a). Comparative differences in Nesoclimacias contractu consists of six chromosome complements among the spe- pairs of autosomes, an m-chromosome pair, cies are listed in Table 2. and an XY sex chromosome pair (Fig. The meiotic processes of these nine 18a). One pair of autosomes is smaller species are much the same as in Dartvin- than the others. The X chromosome is ysius. The description of the meiotic proc- about the same size as the small auto- ess (Fig. 19b-d) is based on observations somes, and the Y is about half the size of O. bimaculatus as an example. The X of the X and a little larger than the m- and Y are positively heteropycnotic in chromosome. The meiotic process of the early prophase and become isopycnotic by species (Fig. 18b, c), is the same as in late diakinesis. The m-chromosomes are

Darwinysius species. unpaired during the prophase and are 19. Oceamdes bimaculatus and at I. — Usinger negatively heteropycnotic metaphase other Oceanides spp. All nine species of 20. Xyonysius basalis (Dallas), X. cali- the genus Oceanides observed have the fornicus (Stal), and X. naso (Van Duzee). same chromosome complement. The nine These three Xyonysius species have the species are Oceanides bimaculatus Usinger, same chromosome constitution. The sper- O. dilatipennis Usinger, O. euphorbiae matogonial metaphase of these species is

Table 1. Relative size differences of chromosome complements in the genus Neseis (Orsil- linae) (EL, extra large; L, large; M, medium-sized; S, small). Sex

No. autosome pairs chromosomes

Species EL M X Y

N. kjrkjildy (Usinger) 5 1/2Y S 1/3X N. ochriasis balduini Usinger 5 2/3Y M 1/3X N. o. macithceps Usinger 5 1/2Y M 1/2X N. o. ochriasis (Kirkaldy) 5 1/2Y M 1/3X N. pallida Usinger 5 1/2Y M 1/2X N. chinai Usinger 5 2/3Y M 1/2X N. jasciata convergent Usinger 4 2/3Y S 2/3X N. fulgida Usinger 5 Y S 1/2X N. hiloensis hiloensis (Perkins) 6 Y M 2/3X N. h. approximata Usinger (E. Maui) 6 2/3Y M 1/2X N. h. approximata Usinger (W. Maui) 6 1/2Y M 2/3X N. h. jugata Usinger 6 2/3Y M 2/3X N. h. interoculata Usinger 6 1/2Y M 1/2X N. sp. near hiloensis 6 1/2Y M 1/2X N. legnota Ashlock 5 2/3Y M 1/2X N. nitida nitida (B. -White) 5 2/3Y M 1/2X N. n. consummata Usinger 5 2/3Y M 1/2X N. n. impressicollis Usinger 5 2/3Y M 1/2X N. n. insulicola (Kirkaldy) 5 2/3Y M 1/2X N. pallassata Ashlock 5 2/3Y M 1/3X N. sanndersiana (Kirkaldy) 6 1/2Y M 1/2X N. silvestris (Kirkaldy) 5 2/3Y S 2/3X Cytotaxonomy of Lycaeidae 731

Orsillinae t I METRARGINI f/A & lib | ,, c #5 I •» I ••, • • f I 19 Oceanides bimaculatus

a a b

20 Xyonysius basalis

NYSIINI a b •/# • • ft «&••••• ill |:M| f 21 Nesomartis psammophila

a i£, n |. in »v»

22 Nysius abnormis

c

in i I,,tt I 23 Nysius tenellus

' « • I ?• #1 , 24 Rhypodes clavicornis

Fig. 19-24. Chromosomes of named species of Orsillinae: a, spermatogonia! metaphasc; b, first metaphasc; c, second metaphasc (Exception Fig. 19: c and d, second metaphasc.) Scale = 10 /an. 732 The University of Kansas Science Bulletin

one composed of six pairs of autosomes, an spermatogonial metaphase set, pair sex of autosomes is much than the m-chromosome pair, and an XY pair very larger of others. The chromosome is smaller (Fig. 20a). In X. basalts, two pairs X autosomes are smaller than the other four. than any of the autosomes and is about The X chromosome is equal in size to the three times as large as the Y. The m- small autosomes. The Y is about half the chromosome is about half the size of size of the X and the m-chromosome is the Y. half the size of the Y. In X. calijornicus, The course of meiosis of this species is similar to that of Darwin- only one of the six pairs of autosomes is (Fig. 21b, c) smaller than the others. The X chromo- ysius marginalis except that the m-chro- lies the of the some is larger than the small-sized auto- mosome on periphery spin- somes but smaller than the medium-sized dle at metaphase II (Fig. 21c). ones. The Y is smaller than the 22. abnormis and other slightly Nysius— Usinger X and larger than the m. In X. naso, two Nysius. spp. The following 19 species of the six pairs of autosomes are a little have been observed cytologically and are smaller than the others. The X chromo- the same in their chromosome cytology: some is the same size as the small-sized Nysius abnormis Usinger, N. angustatus autosomes. The Y is slightly smaller than Uhler, N . beardsleyi Ashlock, N. caledo- the X and is twice as large as the m-chro- niae Distant, N. coenosulus Stal, N . com- mosomes. munis Usinger, N. ericae (Schilling) (= The course of meiosis (Fig. 20b, c) is, in N. natalensis Evans), N. jullawayi Using-

- essential features, the same as in Darwin er, N. huttoni B.-White, N. lichenicola ysms. The X and Y are positively hetero- Kirkaldy, N. longicollis Blackburn, N. pycnotic in early prophase and become nemorivag'its B.-White, N. niger Baker, isopycnotic in late diakinesis. The m- N. raphanus Howard, N. scutellatus Dal- chromosomes are unpaired during pro- las, N. stali Evans, N. usitatus Ashlock, phase and are negatively heteropycnotic at N. vinitor Bergroth, and Nysius sp. (mix- the first metaphase. tus?). The spermatogonial metaphase of these 19 species consists of five pairs of Nysiini. autosomes including one extremely large 21. Nesomartis of and an XY — psammophila Kirkaldy. pair, a pair m-chromosomes, The diploid chromosome complement of sex pair (Fig. 22a). In the metaphase set, Nesomartis psammophila consists of five the smallest pair invariably is the m-chro- of of size pairs autosomes, an m-chromosome pair, mosome. Comparative differences 19 and an XY sex pair (Fig. 21a). In the in chromosome constitution of these

Table 2. Relative size differences of chromosome complements in the genus Oceamdes (Or- sillinae) (EL, extra large; L, large; M, medium-sized; S, small).

No. autosome pairs

Species O. bimaculattis Usinger O. dilatipennis Usinger ....

O. citphorbiac Ashlock .... O. josbergi Usinger O. gressitti Ashlock O. montivagits (Kirkaldy) O. nimbatus (Kirkaldy) .. O. ventralis Usinger

O. yoshimotoi Ashlock .... Cytotaxonomy of Lygaeidae 733

species are shown in Table 3. For exam- the genus. The diploid chromosome num- in ple, N. abnormis, the X chromosome ber of this species is 22 instead of 14. The is about equal to the small-sized autosomes spermatogonial metaphase consists of nine and is about three times as as of large the Y. pairs autosomes, an m-chromosome pair, The m-chromosomes are about half the and an XY sex pair (Fig. 23a). Four of size of the Y. the nine pairs of autosomes are larger than meiotic The sequence of these 19 spe- the others. There is no extremely large cies is in the same essential features. There- autosome pair, which occurs in all other the detailed fore, description of meiosis is species of the genus so far observed (see based on observation of N. abnormis. The Table 3 and Fig. 22a). The X chromo- are X and Y positively heteropycnotic in some is not easily distinguished from the early prophase and become isopycnotic by autosomes, but may be intermediate be- late diakinesis. The m-chromosomes are tween large- and small-sized autosomes as unpaired during the prophase and are shown by inspection of size relationship negatively heteropycnotic at the first meta- at the second metaphase (Figs. 23c, 131f). phase. At the first metaphase, five auto- The Y chromosome is about one-third of somal bivalents occupy the periphery of a the X in size. The m-chromosomes are a spindle while the X and Y univalents little smaller than the Y and are the and the m-chromosome lie in the center smallest component in the set. The meiot- of the spindle (Fig. 22b). At the second ic sequence of the species (Fig. 23b, c) is metaphase, autosomes and the m-chro- essentially the same as in other Nysius. mosome lie on the of a hollow periphery 24. Rhypodes clavicornis— (Fabricius) spindle while the XY pseudopair occupies and R. myersi Usinger. Rhypodes clavi- the center of the cornis and R. are the same in their spindle (Fig.—22c). myersi 23. Nysius tenellus Barber. The chro- chromosome cytology. The spermatogonial mosome complement of Nysius tenellus is metaphase contains five pairs of autosomes, different from those of other species of a pair of m-chromosomes, and an XY sex

Table 3. Relative size differences of chromosome complements in the genus Nysius (Orsil- linae) (EL, extra large; L, large; M, medium-sized; S, small). Sex No. autosome chromosomes pairs ~~ Species EL M X Y N. abnormis Usinger 1/2Y S 1/3X N. angustatus Uhler 2/3Y M>X 1/3X N. beardsleyi Ashlock 1/2Y S 1/2X V. caledoniae Distant 2/3Y S 1/3X N. coenosulus Stal 2/3Y S 1/3X N. communis Usinger 1/2Y M 1/4X N. ericae (Shilling) (= N. natalensis Evans) 2/3Y S 1/2X N. jullawayi Usinger Y S 1/3X N. huttoni B. -White Y S 1/4X N. lichenicola Kirkaldy Y S 1/3X N. longicollis Blackburn 1/2Y S 1/2X N. nemorivagus B. -White Y M 1/3X N. niger Baker Y M 1/4X N. raphanus Howard 2/3Y S 1/3X N. scutellatus Dallas Y M 1/3X N. stali Evans Y S 1/2X N. tenellus Barber 2/3Y M>X 1/3X N. usitatus Ashlock 2/3Y S 1/3X N. vinitor Bergroth Y S 1/3X N. sp. (?mixtus) Y S 1/3X 734 The University of Kansas Science Bulletin

pair (Fig. 24a). One of the five pairs of ogy of Ortholomus nevadensis and O. autosomes is extremely large. The X chro- usingeri is the same in essential features. mosome is a little smaller than the four The male diploid chromosome comple- pairs of small autosomes and is about four ments consist of five pairs of autosomes, times as as large the Y. The m-chromo- an m-chromosome pair, and an XY sex somes are slightly larger than the Y. pair (Fig. 27a). In the spermatogonial of 0. The course of meiosis in these species metaphase nevadensis, two pairs of autosomes are than the other three (Fig. 24b, c) is the same as in Nysitts spe- larger One of these is cies. The m-chromosome is negatively het- pairs. large pairs ex- eropycnotic in metaphase II. tremely large. The X chromosome is a little smaller than the small-sized auto- Orsillini. somes and about three times as large as the Y. The m-chromosomes are in 25. Hudsona anceps (B.-White).—The equal size to the Y. In O. size rela- diploid chromosome complement of Hud- usingeri, tionships in the spermatogonial set are sona anceps consists of five pairs of auto- almost the same as in O. nevadensis. How- somes, an m-chromosome pair, and an XY ever, the m-chromosomes are sex chromosome pair (Fig. 25a). One of slightly smaller than the Y. The course of meiosis the five pairs of autosomes is extremely in these species (Fig. 27b, c) is as in large. The X chromosome is a little small- Hudsona and er than the small-sized autosomes and anceps Nysius species. about four times as large as the Y. The Isch n orhynchinae m-chromosome is almost equal in size to the Y. Three and seven of the The meiotic sequence of the spe- genera species are now cies (Fig. 25b, c) is the same as in Nysius subfamily Ischnorhynchinae known All the species. cytologically. species show 14 (12 + in their chromosome com- 26. Ortholomus arphnoides Baker and XY) — plements, including a pair of the m-chro- O. scolopax (Say). Ortholomus arph- mosomes. Scudder (1962) a noides and 0. scolopax are the same in suggested possible relationship between Ischnorhyn- their chromosome cytology. The diploid chinae and the Orsillinae from the evi- chromosome complement consists of six of of dence the dorsal position of the abdom- pairs autosomes, an m-chromosome pair, inal spiracles, the structure of the oviposi- and an XY sex pair (Fig. 26a). In the tor, and the chromosome number. The spermatogonial metaphase, there are one chromosome numbers in the Ischnorhyn- extremely large pair, four medium-sized chinae are the same as in many Orsillinae, pairs, and one small pair of autosomes. but in Ischnorhynchinae there is no ex- The X chromosome belongs to the me- autosome which is a dium-sized group of autosomes. In O. tremely large pair, characteristic of the Orsillinae. Also, the arphnoides, the Y chromosome is about behavior of the and the m-chromo- half the size of X, Y, the X and slightly larger than the some during meiosis is quite different, m-chromosome. In O. scolopax, at the first from the Y is one-third the size of the X and particularly metaphase, the same size as the m-chromosome. The that in the Orsillinae. Therefore, so far meiotic as chromosome is the sequence of these species (Fig. cytology concerned, is the 26b, c) same as in Hudsona anceps Ischnorhynchinae seem not to be closely and Nysius species described previously. related to the Orsillinae. In the Ischno- 27. Ortholomus nevadensis Baker and rhynchinae, the m-chromosome always 0. usingeri Ashloc\.—Chromosome cytol- takes a central position at metaphase I, but Cytotaxonomy of Lygaeidae 735

Orsillinae -P.-tb ORSILLINI |l; in •^'j 25 Hudsona anceps

a b * c T^~ t | f I

••• • •• i 1 *b Ortholomus arphnoides

a b ## |!fi f '; •

2/ Ortholomus nevadensis

Ischnorhynchinae SI• f b . <-

28 Caprhiobia pallipes

a b *• 0.%% t I . J

29 Kleidocerys franciscanus

*•.«• till i m to •£ V ii * JU Pylorgus colon

Fig. 25-30. Chromosomes of named species of Orsillinae and Ischnorhynchinae: a, spermatogonia! metaphase; 30: second Scale = 10 b, first metaphase; c, second metaphase. {Exception Fig. d, anaphase.) ^m. 736 The University of Kansas Science Bulletin the X and Y are peripheral in Caprhiobia the five pairs of autosomes is smaller than and Kleidocerys, and the X is peripheral the others. The X chromosome resembles and the Y is central in Pylorgus. At the medium-sized group of autosomes the and is not the metaphase II, the XY pseudopair and easily distinguished from m are central in both Caprhiobia and autosomes. In both K. jranciscanus and Pylorgus, while the XY pseudopair is K. modestus, the Y chromosome is about central and the m-chromosome is periph- one-third the size of the X and twice as eral in Kleidocerys. large as the m-chromosome. In K. obo- vatus, the Y is half as as the X and 28. Caprhiobia pallipes Scudder and large — twice as large as the m-chromosome. C. sp. (#116). These two Caprhiobia meiotic of these species are the same in essential features The sequence species of their chromosome systems. The sper- at metaphase I (Fig. 29b) is the same as matogonial metaphase in both consists of in Caprhiobia pallipes. As the second five pairs of autosomes, an m-chromosome metaphase is formed, the autosomes and the the pair, and the X and Y sex chromosomes m-chromosome occupy periphery of a while the lies (Fig. 28a). In both species, one of the spindle XY pseudopair in the center of the five pairs of autosomes is larger than the spindle (Fig. 29c). others. The X chromosome is similar in The peripheral position of the m-chromo- is that size to the four medium-sized pairs of some at second metaphase unlike in autosomes, and is not easily distinguished of the m Caprhiobia pallipes. from the autosomes. The Y is about two- 30. Pylorgus colon (Thunberg).—The thirds the size of the is more than X and spermatogonial metaphase of Pylorgus twice as as the m-chromosome. large colon consists of five pairs of autosomes,

The course of meiosis in these species a pair of the m-chromosomes, and an XY is a little different from others described. sex pair (Fig. 30a). One of the five pairs At the first metaphase, five autosomal of autosomes is larger than the others. tetrads and the X and Y dyads are usu- The X chromosome is like the me- of autosomes and is not ally located on the periphery of a spindle dium-group easily is about and form a ring with the unpaired m- distinguished. The Y chromosome chromosomes in the center (Fig. 28b). one-quarter the size of the X and about The peripheral position of the sex chro- equal in size to the m-chromosome. mosomes at the first is unusual metaphase The meiotic sequence of the species is in lygaeids. However, the second division similar to that in Kleidocerys jranciscanus, of these is orthodox. The X species quite but not exactly the same. At metaphase I, and Y pseudopair and the m-chromosome five autosomal bivalents and the X chro- lie in the center of of a ring autosomes mosome lie on the periphery of a spindle, (Fig. 28c). but usually the Y chromosome lies in the

29. Kleidocerys jranciscanus (Stal), K. center of the spindle. The m-chromosome modestus and K. obovatus takes a central in the — Barber, (Van always position Duzee). The chromosome cytology of spindle (Fig. 30b). At metaphase II, the these three species of Kleidocerys is the autosomes orient on the periphery while same as in Caprhiobia pallipes in essential the XY pseudopair and the m-chromosome features. The diploid chromosome com- occupy the center of the spindle (Fig. 30c). plement consists of five pairs of autosomes, As is usual in lygaeids, the m-chromosome an m-chromosome pair, and an XY pair is negatively heteropycnotic even at ana-

(Fig. 29a). In these three species one of phase II (Fig. 30d). Cytotaxonomy of Lygakidae 737

Cyminae heteropyenotic in the early prophase. They are double structures of two sis- The subfamily Cyminae as a group has composed ter chromatids by the late the highest chromosome numbers in the diplotcne stage and are isopyenotic by late diakinesis. The Lygaeidae. In the Cymini, the two gen- autosomes reveal one chiasma on each, era known cytologically, Cymodema and and the terminalization of chiasmata is Cymus, are 28 (26 + XY) and 30 (28 + completed by the prometaphase. The m- XY). Nesocymus, recently placed in the chromosomes are unpaired during the tribe Ontiscini (Hamid, 1975), is 22 (20 pro- and are at + XY). In the Ninini, three genera and phase negatively heteropyenotic the first metaphase. They maintain this four species have been investigated cyto- condition of negative heteropyenosis un- logically. The species of both Cymoninns til the completion of meiosis. and Ninomimus also show 22 (20 + XY). The 13 autosomal tetrads lie on the The genus Nintts has 16 (14 + XY), the lowest number so far known in the sub- periphery of a hollow spindle while the X and Y and the m-chromosome family. dyads the center of the at both The chromosome arrangement of the occupy spindle the first and the first and second metaphase in the Cyminae metaphase (Fig. 31b) second The first is variable. In the genera Cymus and (Fig. 31c). metaphase of chromosomes in these Cymodema, the X, Y, and m take a cen- arrangement spe- cies is not affected the chromo- tral position, which is usual in lygaeids, by high some there tends to be at both first and second metaphase. How- numbers, although some disorder, which also ever, in Nesocymus of the Ontiscini and accompanies chromosome numbers in the other all the genera so far observed of Ninini, high families of The first division the X, Y, and m locate in the center of Heteroptera. is for the sex chromosomes and a spindle at the first metaphase, but the equational reductional for the m-chromosome. m takes a peripheral position at the sec- ond metaphase. The chromosome cytology of Cymus luridus was The distribution pattern of chromo- reported by Montgomery He observed the first meta- some complements of the Cyminae is (1901£). only and stated that there were given in Figure 134. phase simply 15 chromosome entities. From his de-

Cymini. scription and illustrations, we can easily the of the m-chromo- 31. Cymus coriacipennis (Stal), C. lun- recognize presence some, but he did not say anything about dus Stal, and C. sp. from Sierra, Califor- — the sex-chromosome mechanism. From nia. The diploid chromosome comple- his observations, his might be ment of these Cymus species consists of 13 specimens 12A + m + XY at I. If this pairs of autosomes, an m-chromosome metaphase is true, the chromosome com- pair, and an XY sex pair (Fig. 31a). All assumption of his and ours are the autosomes are similar in size. The X plements specimens different. chromosome is not distinguishable from — the autosomes. The Y chromosome is a 32. Cymus sp. (near waelbrocJ^i). The little smaller than the autosomes and about diploid chromosome complement of this is less one of auto- four times as large as the m-chromosome. Cymus species by pair somes than that of the described The essential features of meiosis in previously The spermatogonial metaphase these three species are quite typical of the species. consists of 12 of autosomes, a pattern of lygaeids described previously. pairs pair of and the sex chro- The X and Y chromosomes are positively m-chromosomes, XY 738 The University of Kansas Science Bulletin

Cyminae •• w w a •ft ••w bD f C • # § l«»»l,»^ CYMINI •• * I • ran ', i II. .• I ••• * ™ 31 Cymus coriacipennis

-^ a |*l *| b l* fl, c $& i r.» i i.; •»

32 Cymus sp. W near waelbroecki

b c .*..* § »t«| ,|lll t '••••»l ••mi $&JO Cymodema basicornis ONTISCINI a b ...... !0i •••• ••!•'•

On Nesocymus calvus • NININI * k I » . c I •' #•• a b ••••Id

35 Cymoninus notabilis

*•• .••:•. »; j »,V 00 Ninus insignis

Chauliopinae a b I' ••?* A • • •t m

f • 37«' Chauliops bisontula

Fig. 31-37. Chromosomes of named species of Cyminae and Chauliopinae: a, spermatogonial metaphase; b, first metaphase; c, second metaphase. (Exception Fig. 3 5: b and c, first metaphase; d, second metaphase.) Scale = 10 /im. Cytotaxonomy of Lygaeidak 739 mosomcs (Fig. 32a). One pair of auto- during prophase and are negatively hetero- somes is larger than the others and is pycnotic at the first metaphase. easily recognized. Again, the m-chromo- Ninini. some is the smallest component in the set. The course of meiosis 32b, in (Fig. c) 35. Cymoninus notabilis (Distant) and essential features is and is quite orthodox, C. turaensis (Paiva).—The chromosome like that in Cymus coriacipennis. cytology of Cymoninus notabilis and C. 33. basicornis turaensis is the same in — Cymodema Motschulsky. essential features. The chromosome cytology of Cymode- The spermatogonial metaphase consists of ma basicornis is essentially similar to that nine pairs of autosomes, a pair of m- of Cymus coriacipennis. The spermato- chromosomes, and an XY sex pair (Fig. gonia! metaphase consists of 13 pairs of 35a). The nine pairs of autosomes are

autosomes, an m-chromosome pair, and an similar in size, and the X and Y are in- XY sex pair (Fig. 33a). All the autosomes distinguishable from the autosomes. The except the m pair are similar in size. The smallest component is the m-chromosomes. m is the smallest pair component, easily The meiotic sequence (Fig. 35b-d) is from the others. The X is distinguished as in Nesocymus calvus. The first meiotic not detectable, since it is the same size division is reductional for the m-chromo- as the autosomes. the Y is However, some and equational for the X and Y smaller than the autosomes. The course chromosomes. In C. notabilis, the Y chro- of is as in meiosis (Fig. 33b, c) Cymus mosome is about one-third the size of the

coriacipennis. X and twice as large as the m-chromo- some. In C. turaensis, the X is about twice Ontiscini. as large as the Y, which is three times as — as the m-chromosome. 34. Nesocymus caluus (B.-White). large — The male diploid chromosome comple- 36. Ninus insignis Stal. The diploid ment of Nesocymus calvus consists of nine chromosome complement of Ninus insig- pairs of autosomes, an m-chromosome nis consists of six pairs of autosomes, an pair, and an XY sex pair (Fig. 34a). The m-chromosome pair, and an XY sex pair nine pairs of autosomes are roughly simi- (Fig. 36a). In the spermatogonial meta- lar in size. The X and Y chromosomes phase, the six pairs of autosomes are simi- are not distinguishable from the autosomes lar in size. The X chromosome is not dis- by size. However, from comparison with tinguishable by size from the autosomes, the second metaphase, the X may belong but the Y is a little smaller than the auto- to the larger-sized group of autosomes and somes. The m-chromosomes are about the Y to the medium-sized group. The one-third the size of the Y. The meiotic m-chromosomes are the smallest compo- process (Fig. 36b, c) is as in Cymonius nents of the spermatogonial metaphase set notabilis. and easily distinguished. Chauliopinae The course of meiosis in the species one and two of the (Fig. 34b, c) is as in Cymus luridus except Only genus species have been studied that, at the second metaphase, the m- subfamily Chauliopinae chromosome orients on the periphery of cytologically. the spindle. The X and Y chromosomes 37. Chauliops bisontula Banks and C. are positively heteropycnotic in early pro- jallax Scott.—The essential features of phase and become isopycnotic by late dia- chromosome cytology in Chauliops bison- kinesis. The m-chromosomes are unpaired tula and C. jallax are the same. The male 740 The University of Kansas Science Bulletin

found in the is characteristic of diploid chromosome complement consists Orsillinae, of m- the of six pairs of autosomes, a pair subfamily. chromosomes, and an XY sex pair (Fig. The genus Ischnodernus is a rather in- the 37a). In spermatogonial metaphase, teresting group. The species with 16 chro- one pair of autosomes is very much larger mosomes are distributed in temperate re- others. the X chromo- than the Although gions and the species with 14 chromosomes is not from the auto- some recognizable are found in the tropics. The species with somes by size, the Y is easily distinguished 14 chromosomes always carry one pair of it is smaller than all but the m-chro- since extremely large autosomes, but the species mosomes. The m-chromosomes are the with 16 chromosomes do not. Therefore, smallest in the set. component the species with 16 chromosomes seem to In the meiotic sequence, the X and Y be derived from the 14-chromosome spe- of the one chromosomes are positively heteropycnotic cies by fragmentation large autosome The distribution in early prophase. They are in nonhomol- pair. pattern be correlated ogous association and are double structures of chromosome numbers may composed of two sister chromatids at the to the evolution and dispersal of the spe- cies in the Ischnodernus. Such a diffuse stage. Right after the diffuse stage, genus is also found in Chro- they separate from each other and they be- situation Macropes. in the of Blissi- come isopycnotic by late diakinesis. The mosome cytology species m-chromosomes are unpaired during the nae is quite orthodox. The X, Y, and m at both first and prophase and are negatively heteropycnotic take a central position at the first metaphase. Immediately after second metaphase. nature of the the diffuse stage, the tetrad 38. Atrademus capeneri (Slater) and A. are six bivalents becomes evident. They maritimus Slater and Wilcox.—The sper- chiasma in usually associated by one each, matogonial metaphase of these two Atra- the terminalization of chiasmata is auto- and demus species consists of five pairs of completed by the prometaphase. somes, an m-chromosome pair, and the X One As the first metaphase is formed, six and Y sex chromosomes (Fig. 38a). autosomal tetrads occupy the periphery of of the five pairs of autosomes is extremely than the and a spindle while the X and Y dyads and large, much larger others, relative sizes of the m-chromosome lie in the center of the easily distinguished. The in these two spindle (Fig. 37b). The first meiotic divi- the chromosome complements in Table 4. sion is equational for the sex chromosomes species are given and reductional for the m-chromosomes. The course of meiosis in these two spe- At the second metaphase, the autosomes cies is the same in every essential feature. orient of a I the again on the periphery spindle As usual in lygaeids, at metaphase and the XY pseudopair and the m-chro- autosomal tetrads arrange themselves in lie in of the mosome the center spindle the periphery of a spindle while the m- (Fig. 37c). chromosomes and the X and Y dyads lie in the center of a ring formed by the auto- Blissinae somes (Fig. 38b). As metaphase II is formed, the m-chromosomes and the XY Ten genera and 37 species of the sub- are located in the center family Blissinae have been cytologically pseudopair again of a formed by five autosomal dyads studied. Of these, 23 species are 14 (12 + ring XY), including a pair of m-chromosomes (Fig. 38c). Blissus arenarius Barber and other and always one pair of extremely large 39. chromo- autosomes. This status, which is also species in the genus Blissus.—The Cytotaxonomy of Lygaeidae 741

Blissinae a • % 1 i ; '£•• > 38 Atrademus capeneri /

••'•• a 742 The University of Kansas Science Bulletin some cytology of the following four species and the X and Y sex chromosomes (Fig. of of the genus Blissus is essentially the same 40a). Two pairs autosomes are slightly in observed features: Blissus arenarius larger than the other four pairs. The m- Barber, B. leucopterus leucopterus (Say), chromosome is the smallest component in B. mixtus Barber, and B. omani Barber. the set. The meiotic process of the species The male diploid chromosome comple- (Fig. 40b, c) is the same in essential fea- ment consists of five pairs of autosomes, tures as Blissus arenarius. sex an m-chromosome pair, and an XY 41. Cavelerius illustris Distant.—The One of the five autosome pair (Fig. 39a). male diploid chromosome complement of is Relative size pairs extremely large. Cavelerius illustris consists of five pairs of differences of chromosomes in all the spe- autosomes, an m-chromosome pair, and are in Table 4. As an cies given example, an X1X2Y multiple sex pair (Fig. 41a). in arenarius the chromosome is B. X In the spermatogonial metaphase, one of smaller than the medium-sized slightly the five autosome pairs is extremely large, of autosomes. The Y chromosome group much larger than the others. The Xi is about one-third as as the X and a large chromosome is not distinguishable from little larger than the m-chromosome. The the smaller-sized autosomes. However, in all these process of meiosis species (Fig. the X2 and Y can be recognized from the 39b, is as in Atrademus autosomes because of their smaller size. c) — capeneri. 40. Capodemus spp. This collection of They are similar in size. The m-chromo- Capodemus specimens has recently been somes are the smallest component in the found to contain two species: C. sabulosus metaphase set and readily distinguished Slater and Sweet and C. pentameri Slater from the rest of the chromosomes. and Sweet. The following discussion ap- The essential features of meiosis in the to both has one plies species. Capodemus species (Fig. 41b, c) are as in Blissus are- more pair of autosomes than the preceding narius. The Xi, X2, and Y chromosomes Since has no extreme- species. Capodemus are positively heteropycnotic in early pro- ly large pair of autosomes, it is possible phase. They are associated with each that an extremely large pair of autosomes other at the diffuse stage. At the early in an ancestor fragmented to make two diplotene stage, they have separated from pairs of autosomes. The spermatogonial one another and each is a double structure metaphase of this species consists of six composed of two sister chromatids. These pairs of autosomes, an m-chromosome pair, three sex chromosomes become isopycnotic

Table 4. Relative size differences of chromosome complements in the genera Atrademus, Blissus, and Dimorphopterus (Blissinae) (EL, extra large; L, large; M, medium-sized; S, small). Sex

No. autosome pairs chromosomes

Species EL M X Y

Atrademus capeneri (Slater) 4 1/3Y M 2/3X A. maritimus Slater and Wilcox 4 1/2Y M 1/2X Blissus arenarius maritimus Leonard 4 2/3Y M>X 1/3X B. leucopterus hirtus Montandon 3 2/3Y M 1/2X B. mixtus Barber 3 2/3Y M 1/2X B. omani Barber 4 Y M>X 1/2X B- sp. (#57) 4 Y M>X 1/2X

Dimorphopterus annulatus (Slater) .. 4 1/2Y M 1/2X D. blissoides (Baerensprung) 4 Y M 1/2X D. oblongus (Fabricius) 4 2/3Y M 1/2X D. syrtis Slater and Wilcox 4 Y M>X 1/2X Cytotaxonomy of Lygaeidae 743

late — by diakinesis. The m-chromosomes lock, and Wilcox. The male diploid chro- are unpaired during the prophase and are mosome complement of Geoblissus me- negatively heteropyenotic at the first meta- kpngensis consists of five pairs of auto- phase. The first meiotic division is reduc- somes, a pair of m-chromosomes, and an tional for the m-chromosome and equa- XY sex pair (Fig. 44a). In the spermato- tional for the sex chromosomes. In the gonial metaphase, one of the five autosome second the is anaphase, Xi and X2 segregate pairs extremely large, much larger than to one pole with one set of autosome the others. The X chromosome is equal in halves and the Y goes to the other pole size to the smaller-sized group of auto- with the other set (Fig. 41d). somes. The Y chromosome is about one-

third smaller than the and is a 42. Cavelerins minor Slater and Miya- X little — than the moto. The chromosome complement of larger m-chromosome. The course of in Cavelerius minor is somewhat different meiosis the species (Fig. 44b, is as in Blissus arenarius. from that of C. illustris described pre- c) viously. The spermatogonial metaphase 45. Ischnodemus badius Van Duzee, in plate C. minor consists of five pairs of /. brunnipennis (Germar), /. conicus Van

an m-chromosome and an /. /. autosomes, pair, Duzee,— jalicus (Say), and slossoni Van XY sex pair (Fig. 42a) instead of the Duzee. The chromosome cytology of X1X2Y multiple sex pair of C. illustris. these five species of Ischnodemus is the One of the five is autosome pairs ex- same in essential features. The male dip- tremely large. The X chromosome is loid chromosome complement consists of slightly smaller than the autosomes and six pairs of autosomes, a pair of m-chro- the is Y smaller than the X. The m-chro- mosomes, and an XY sex pair (Fig. 45a). mosomes, the smallest component in the Relative size differences of chromosome diploid set, are readily distinguished from complements in these species are given in the rest of the chromosomes. The course Table 5. For example, in /. badius the of meiosis (Fig. 42b, c) is the same as in six pairs of autosomes are similar in size. Blissus arenarius. The X chromosome is smaller than the autosomes but than the Y. The 43. Dimorphopterus blissoides (Baeren- larger m-chromosomes are about half the size of sprung), D. annulatus (Slater), D. latus the Y and are the smallest in (Distant), D. oblongus (Stal), and S. components — the set. syrtis Slater and Wilcox. The male dip- loid chromosome complement of these During meiosis, the X and Y chromo- five Dimorphopterus species consists of somes are positively heteropyenotic in the five pairs of autosomes, an m-chromosome early prophase and become isopyenotic by pair, and an XY sex pair (Fig. 43a). One late diakinesis. They reveal nonhomolo- of the five autosome pairs is extremely gous association at the diffuse stage and large, much larger than the others. The separate from one another at the diplotene X chromosome belongs to the medium- stage. At the diplotene stage, they are sized group of autosomes and is slightly double structures composed of two sister larger than the smallest pair of autosomes. chromatids. The autosomes become evi- The Y chromosome is about half the size dent right after the diffuse stage and pass of the as X and twice as large the m-chro- into a typical diakinesis. The m-chromo- mosome. The course of meiosis in these somes are unpaired during the prophase; five is as in Blissus species (Fig. 43b, c) they are negatively heteropyenotic at the arenarius. first metaphase and maintain this condi- 44. Geoblissus mef^ongensis Slater, Ash- tion through the completion of meiosis. 744 The University of Kansas Science Bulletin

t Blissinae t ft c a * • •JR» ••:• it ••• L* < i

45 Ischnodemus badius

-.#• a # • b t m

46 Ischnodemus noctulus

•••' •«" t » t I ft • 47 Ischnodemus notandus^

•••• t » 4« Macchiademus diplopterus

a $ b c tt 49 Macropes varipennis

*•»%*** t,,u * m"90 OU Macropes obnubilis

#•••# • ft • • •* I

51 Micaredemus pusillus Gk W

Fig. 45-51. Chromosomes of named species of Blissinae: a, spermatogonial metaphase; b, first metaphase; c, second metaphase. Scale = 10 fim. Cytotaxonomy of Lygaeidae 745

The course of meiosis in these species chromosome belongs to the smaller-sized of is (Fig. 45b, c) is as in Blissus arenarius. group autosomes and slightly larger than the which are the The chromosome cytology of /. falicus m-chromosomes, smallest in the set. The mei- has been reported by Montgomery (1901/?, component otic of the 47b, 1906). His findings are confirmed by our sequence species (Fig. c) observations. is similar to that in Blissus arenarius. 48. 46. Ischnodemus noctulus Distant, /. Macchiademus diplopterus (Dis- —The essential features of chromo- nigrocephalus Slater, Ashlock, and Wil- tant). some in Macchiademus cox, /. oblongus (Fabricius), /. brevicornis cytology diplop- — terus are the same as in Atrademus (Stal), and /. tibialis Stal. These five capen- in eri. The con- species of Ischnodemus are the same spermatogonial metaphase sists of five of autosomes, an m- their chromosome cytology, but they are pairs chromosome and the X and Y sex different from other Ischnodemus species pair, chromosomes 48a). One of the five described previously. The male diploid (Fig. autosome is much chromosome complement of these species pairs extremely large, than the others. The meiotic se- consists of five pairs of autosomes, an m- larger is as in Blissus arenarius (Fig. chromosome pair, and an XY sex pair quence 48b, (Fig. 46a). One of the five pairs of auto- c). M. somes is extremely large, much larger 49. Macropes varipennis (Walker), M. and M. than the others. Relative size differences raja Distant, — uniformis Distant, of the chromosome complements in these sp. (PDA-41). The chromosome cytology of these four of is the species are given in Table 5. For exam- species Macropes is same in essential features. The ple, in /. noctulus the X chromosome diploid the same size as the medium-sized auto- chromosome complement in the male con- somes and the Y is smaller than the X. sists of five pairs of autosomes, a pair of The m-chromosomes are the smallest com- m-chromosomes, and an XY sex pair of the five autosome ponents in the set and are about two-thirds (Fig. 49a). One the size of the Y. The course of meiosis pairs is extremely large, much larger than

is to the others. Relative size differences of of these species (Fig. 46b, c) similar that of Blissus arenarius. chromosome complements in these spe- cies are listed in Table 5. The course of 47. Ischnodemus notandus Slater and meiosis in the is as in Wilcox.—The chromosome cytology of species (Fig. 49b, c) Ischnodemus notandus is different from Blissus arenarius. Ischno- — that of other species of the genus 50. Macropes obnubilis (Distant). The demus so far studied cytologically. The chromosome constitution of Macropes male chromosome diploid complement obnubilis is different from that in other an consists of seven pairs of autosomes, chro- Macropes species. The male diploid m-chromosome pair, and an XY sex pair mosome complement consists of six pairs (Fig. 47a). In the spermatogonial meta- of autosomes, an m-chromosome pair, and phase, one of the seven pairs of autosomes an XY sex The six the pair (Fig. 50a). pairs is extremely large, much larger than of autosomes are similar in size. The X others. The remaining six pairs are simi- chromosome to the medium-sized lar in size; however, two of them are belongs of autosomes and the Y is half the slightly smaller than the other four pairs. group are The X chromosome belongs to the me- size of the X. The m-chromosomes dium-sized group of autosomes and is not one-third the size of the Y and are the in the set. The mei- easily distinguished from them. The Y smallest components 746 The University of Kansas Science Bulletin

otic is process of the species (Fig. 50b, c) than twice as large as the rest), an m- as in Bliss us arenarius. chromosome pair, and the X and Y sex — chromosomes The m-chromo- 51. Micaredemus piisillus (Dallas). (Fig. 52a). somes are the smallest Micaredemus pusillus shows the same component in the set. The to the chromosome pattern as Macropes obnu- X belongs medium-sized bilis. The spermatogonial metaphase con- groups of autosomes and the Y is smaller than the X. sists of six pairs of autosomes, an m-chro-

mosome pair, and an XY sex pair (Fig. The meiotic sequence of the species is 51a). One of the six autosomal pairs is quite orthodox in every feature. The X the is larger than others. The m pair the and Y are heteropycnotic during the pro- smallest member of the set. The X chro- phase and the m-chromosomes are un- mosome belongs to the medium-sized paired during the prophase. At the first group of autosomes, and so is not distin- metaphase, as is usual, the five autosomal guishable from the autosomes. However, tetrads locate on the periphery of a spindle the is half the size of Y the X and more while the X and Y dyads and the m pair than twice as large as the m. The course lie in the center of a ring formed by the of meiosis (Fig. 51b, c) is quite orthodox autosomes (Fig. 52b). As the second meta- and is as in Blissits arenarius. phase is formed, the XY pseudopair and the m pair again lie in the center of a ring Henestarinae formed by five autosomal dyads (Fig. 52c).

Only one species of the subfamily Geocorinae Henestarinae has been observed cytologi-

cally. Four genera and 13 species of the sub- 52. Engistus viduus Slater.—The chro- family Geocorinae are now known cyto- mosome cytology of Engistus viduus is logically. In the genus Geocoris, the chro- similar to that of Macropes varipennis in mosome number so far known is quite essential features. The diploid chromo- uniform and is 20 (18 + XY) in the some complement of this species is five diploid male. On the other hand, the pairs of autosomes (one of these is more genus Hypogeocoris shows two types (16

Table 5. Relative size differences of chromosome complements in the genera lschnodemus and Macropes (Blissinae) (EL, extra large; L, large; M, medium-sized; S, small). Sex No. autosome pairs m chromosomes Species EL M lschnodemus baduis Van Duzee

/. brevicornis (Stal) 1 /. brunnipennis (Germar) /. conicus Van Duzee I. jalicus (Say)

/. nigrocephalus Slater, Ashlock, and Wilcox 1

I. noctulus Distant 1

1. notandus Slater 1

/. oblongus (Fabricius) 1 /. slossoni Van Duzee

/. tibialis Stal 1 Macropes obnubilis (Distant) M. raja Distant 1 M. varipennis (Walker) 1

M. uniformis Distant 1

M. sp. (PDA-41) 1 Cytotaxonomy of Lygaeidae 747 £ rlenestarinae •8?:" ( •:• <»:in •^ t • 3Z Engistus viduus W

Geocorinae

Wi3 n»^~.-;,.Geocoris atricolor„«^;,-~i~.. '

* a lb c |t d

3^ Geocoris varius

I • b I ».c• I. ». . '. ,'g* | ••• • «•*• • • • 30 Germalus sp.

a • h c .'/• •» m •••

ypogeocons piceus

1 , $S i !*. :iti::i t

Piocoris stellatus

Fig. 52-57. Chromosomes of named species of Henestarinae and Geocorinae: a, spermatogonia! metaphase; b, Scale = first metaphase; c, second metaphase. (Exception Fig. 54: c, first anaphase; d, second metaphase.) 10 /am. 748 The University of Kansas Science Bulletin

+ XY and 14 + XY), as does the genus of meiosis, and become isopycnotic by late Piocoris (18 + XY and 14 + XY). At diakinesis. They reveal nonhomologous present it is difficult to judge the modal association at the diffuse stage and sepa- number of the subfamily. Compared to rate from each other once at the diplotene other species in the family, 20 (18 + XY) stage. At the diplotene stage, they are chromosomes is a fairly high chromosome revealed as double structures composed number, found only in the Geocorinae of two sister chromatids. Immediately af- and in the Drymini of the Rhyparochromi- ter the diffuse stage, the autosomes be- nae. come evident and pass into a typical dia- The chromosome behavior during mei- kinesis. The m-chromosomes are unpaired osis in the Geocorinae is somewhat un- during the prophase and are negatively orthodox. The first metaphase is quite heteropycnotic at metaphase I. usual, with the X, Y and m locating in At the first metaphase, eight autosomal the center of a hollow spindle. However, tetrads occupy the periphery of a hollow at metaphase II, the m-chromosome tends spindle while the X and Y dyads and the to arrange on the periphery with the auto- m-chromosome lie in the center of the somes. Of course, the XY pseudopair lo- spindle (Fig. 53b). The first meiosis is cates in the center. reductional for the m-chromosome and

53. Geocoris atricolor Montandon, G. equational for the sex chromosomes. At bullatus (Say), G. pallens (Stal), G. sp. the second metaphase, the autosomes and from and G. the m-chromosome lie on the —Blythe, California, sp. (PDA- periphery 43). These five species of Geocoris are of a spindle but the XY pseudopair occu- the in their chromosome the center of the same cytology. pies spindle (Fig.— 53c). The male diploid chromosome comple- 54. Geocoris varius (Uhler). Geocoris ment of these species consists of eight pairs varins is different from the other Geocoris of autosomes, a pair of m-chromosomes, species described previously in chromo- and an XY sex pair (Fig. 53a). Relative some constitution. The diploid chromo- size differences of the chromosome com- some complement in the male consists of plements in these species are listed in six pairs of autosomes, an m-chromosome In Table 6. In G. atricolor, for example, three pair, and an XY sex pair (Fig. 54a). six pairs of autosomes are slightly larger than the spermatogonial metaphase, pairs the others. The X chromosome belongs to of autosomes and the X chromosome are the smaller-sized group of autosomes and similar in size. The Y chromosome is half is about twice as large as the Y. The m- the size of the X and is larger than the chromosomes are one-third the size of m-chromosome. theY. The course of meiosis of the species

is in Geocoris The X and Y chromosomes are posi- (Fig. 54b, d) the same as tively heteropycnotic in the early prophase atricolor. Figure 54c shows anaphase I.

Table 6. Relative size differences of chromosome complements in the genus Geocoris (Geo- corinae) (EL, extra large; L, large; M, medium-sized; S, small).

No. autosome pairs

Species G. atricolor Montandon G. bullatus (Say) G. pallens Stal G. sp. (PDA-43) G. sp. (from Blythe, Calif.) Cytotaxonomy of Lygaeidae 749

55. Germalus from New Caledonia. all — sp. logically investigated. Essentially, the The diploid chromosome complement species are the same in chromosome cytol- in the male of the Germalus species con- ogy, although three species of Oxycarenus sists of six pairs of autosomes, a pair of have multiple sex chromosomes. A char- m-chromosomes, and an XY sex pair (Fig. acteristic of the subfamily is lack of the 55a). One of the six autosome pairs is m-chromosome. Menon (1955) reported larger than the others. The X chromo- the presence of m-chromosomes in O. hy- some is smaller than the small-sized auto- ahninpennis in some but not all of the somes and is three times as large as the Y. cells within an individual. From his de- The m-chromosomes are about half the scription of meiosis and drawings, the m- size of the Y and are the smallest com- chromosomes in O. hyalinipennis do not ponents in the spermatogonial metaphase behave as they do in other lygaeids. Ap- plate. The meiotic sequence of the species parently, he did not observe in sufficient (Fig. 55b, c) is as in Geocoris atricolor. detail the behavior of the m-chromosomes and we are doubtful of 56. Hypogeocoris piceus (Say).—The during meiosis, the of the m-chromosome. What male diploid chromosome complement of presence Menon were m-chromosomes Hypogeocoris piceus consists of six pairs thought have been either of fractured of autosomes, an m-chromosome pair, and might parts chromosomes or chromo- an XY sex pair (Fig. 56a). In the sper- supernumerary somes. matogonial metaphase, one of the six auto- some pairs is larger than the others. The The behavior of the X and Y during X chromosome is smaller than any auto- meiosis is usual. They are located in some and is twice as large as the Y. The the center of a ring formed by the auto- m-chromosomes are half the size of the Y somes at both metaphase I and metaphase and are the smallest components in the II. set. The course of meiosis — (Fig. 56b, c) 58. Crophius bohemani (Stal). The is as in Geocoris atricolor. spermatogonial metaphase in Crophius bo- 57. Piocoris stellatus Montandon.—The hemani reveals seven pairs of autosomes chromosome cytology of Piocoris stellatus and an XY sex pair (Fig. 58a). Three of is similar to that of Geocoris atricolor, the seven autosomal pairs are larger than previously described. The diploid chro- the others. The X chromosome belongs mosome complement consists of eight pairs to the smaller-sized group of autosomes is chro- of autosomes, an m-chromosome pair, and and not distinguishable. The Y the X and Y sex chromosomes (Fig. 57a). mosome is smaller than the X and is easily Two pairs of autosomes are slightly larger recognized by its size. than the others but not conspicuously so. In meiosis, the X and Y chromosomes The X is the same size as the autosomes; are positively heteropycnotic in the early the Y is smaller than the and more X prophase and become isopycnotic by the than twice as large as the m-chromosome. late diakinesis. They are in nonhomolo- The meiotic of this process species (Fig. gous association at the diffuse stage and is as in Geocoris 57b, c) quite orthodox, separate once in the diplotene stage. At atricolor. 57c shows the side view Figure the diplotene stage, they can be resolved of metaphase II. as double structures. The autosomes be- come evident immediately after the dif- Oxycareninae fuse stage and pass into typical diakinesis. are associated one chias- Three genera and five species in the They usually by subfamily Oxycareninae have been cyto- ma on each, and the terminalization of 750 The University of Kansas Science Bulletin

Oxycareninae Vl JO Crophius bohemani w

a c a ..•.• !..'- b t't ;•, ,,

••• | f • • • J3 Oxycarenus luctuosus

Pachygronthinae a m 9 b c PACHYGRONTHINI *$: | • ••.'•• .. ,., d

60 Oedancala dorsalis

a f b Ate • «t lit II

Dl Pachygrontha bipunctata

b d •••• • ». V.'

D& Pachygrontha longiceps

•/•• a d .••V • • t •••• 00 Pachygrontha barberi

t a t b «.'U 1 •Si

b4 Uttaris pallidipennis

Fig. 58-64. Chromosomes of named species of Oxycareninae and Pachygronthinae: a, spermatogonial meta- phase; b, first metaphase; c, second metaphase; d, second anaphase. Scale = 10 /um. Cytotaxonomy of Lycaeidae 751

chiasmata is completed the ber have been caused by prometa- may either by frag- mentation phase. or by chromatid autonomy, as of is found in The course meiosis is usual. As the Thyanata or Banasa (Schrader first is and metaphase formed, seven auto- Hughes-Schrader, 1956, 1958). Study somal of the tetrads lie on the periphery of a other species in the genus would be spindle, but the X and Y dyads occupy the interesting from the point of view of chro- center of the spindle (Fig. 58b). The first mosomal evolution and the holokinetic meiosis is equational for the sex chromo- nature of the chromosomes. Chromosome somes. At the second metaphase, the auto- cytology during meiosis in the tribe is somes again orient on the periphery of a quite orthodox. The X and m, and the spindle as the XY pseudopair lies in the Y if present, usually locate in the center center of the of a spindle (Fig. 58c). No m- hollow spindle at both first and sec- chromosome is evident. ond metaphase. 59. In the tribe Oxycarenus luctuosus (Montrou- Teracriini, cytological data zier).—The male diploid chromosome is now available for four genera and four All complement of Oxycarenus luctuosus con- species. are 14 (12 + XY), including sists of an seven pairs of autosomes and the m-pair. Fourteen chromosomes may be the X1X2Y multiple sex pair (Fig. 59a). Two modal number in the tribe. Chromo- of the seven some behavior meiosis autosome pairs are slightly during in the tribe larger than the others. The Xi chromo- is somewhat different from that in the some is equal in size to the small auto- Pachygronthini. Although the chromo- somes and the X2 is about half the size some arrangement at metaphase I is as in of the Xi. the The Y chromosome is inter- Pachygronthini, at metaphase II, the mediate in size between Xi and X2. m-chromosome tends to be located on the The meiotic periphery with the autosomes instead of sequence of the species in the central (Fig. 59b, c) is similar to that of Crophius position. bohemani. The In the the Xi, X2, and Y chromo- subfamily Pachygronthinae, somes are positively heteropycnotic in the essential chromosome number is 14 (12 and the early prophase and become isopycnotic by + XY) Y chromosome was lost late in Oedancala diakinesis. In anaphase II, the Xi and and Pachygrontha during the X2 segregate to one pole with one set of process of evolution. autosomes the and Y goes to the other pole with the Pachygronthini. other set (Fig. 59d). As in no Crophius, m-chromosome is present. 60. Oedancala dorsalis (Say).—Oedan- cala dorsalis has been studied cytologically Pack n th inae ygro by Montgomery (1901a, 1906). Our find- In ings confirm his observations. The male the pachygronthine tribe Pachygron- three diploid chromosome of the thini, genera and nine species are complement known species consists of five pairs of autosomes, cytologically. An interesting fea- ture of these an m-chromosome pair, and an X chromo- members of the tribe, except some In the for Uttaris, is the lack of the Y-chromo- (Fig. 60a). spermatogonia! some. The common chromosome number metaphase, the five pairs of autosomes are is 13 similar in size. The X chromosome is (12 + XO), including a pair of m- chromosomes. In Pachygrontha, three smaller than any autosome, and the m- types of chromosome complements were chromosomes are about one-third the size found: 12 + XO, 16 + XO, and 22 + of the X and the smallest component in XO. This deviation from a common num- the set. 752 The University of Kansas Science Bulletin

is The seven of autosomes and During meiosis, the X chromosome 62a). pairs in the the X chromosome are similar in size, positively heteropycnotic early pro- dia- while the m-chromosomes are the smallest phase and becomes isopycnotic by late the distin- kinesis. It can be resolved as a double components in set and easily structure composed of two sister chro- guishable. tetrad matids at the diffuse stage. The The meiotic process of this species (Fig. evident nature of the autosomes becomes 62b, c) is as in Oedancala dorsalis. There and right after the diffuse stage, they pass are two tvpes of anaphase II configurations m-chromo- into typical diakinesis. The (Fig.62d). somes are the unpaired during prophase 63. Pachygrontha barberi Slater.—The and are negatively heteropycnotic. They chromosome complement of Pachygrontha maintain this condition until the comple- barberi is quite different from those of tion of meiosis. other species in the genus Pachygrontha. five auto- As metaphase I is formed, The spermatogonial metaphase of this spe- of a somal bivalents lie on the periphery cies consists of ten pairs of autosomes, an and m-chromo- spindle but the X dyad m-chromosome pair, and a sole X chro- some occupy the center of the spindle (Fig. mosome (Fig. 63a). The ten pairs of auto- 60b). The first meiosis is reductional for somes are similar in size, the X chromo- for the the m-chromosome and equational some is the largest component in the set, X chromosome. At metaphase II, again and m-chromosomes are the smallest. the chromosome and the m-chromosome X The course of meiosis (Fig. 63b, c) lie in the center of a formed the ring by again is as in Oedancala dorsalis. The sole autosomes At II, the (Fig. 60c). anaphase X goes to one pole with autosomes and chromosome moves to one X pole (Fig. the m-chromosome, leaving the other As a result of the second 60d). division, halves with no sex chromosome (Fig. there are two of 5 m types spermatids: + 63d). + X and 5 + m. — 64. Uttaris pallidipennis (Stal). The 61. Stal, P. of Ut- Pachygrontha bipitnctata diploid chromosome complement Distant, P. lineata Germar, and of auto- compacta taris pallidipennis is five pairs P. Stal.—The chromosome nigrovittata cy- somes, an m-chromosome pair, and the X of these four of tology species Pachygron- and Y sex chromosomes (Fig. 64a). The tha is the same in essential features. The chromosome system of the species is some- chromosome male diploid complement what different from that of other genera consists of five of autosomes, an m- in the pairs and species so far observed Pachy- chromosome and an X chromosome Oedancala and pair, gronthini. The genera In the meta- (Fig. 61a). spermatogonial Pachygrontha have shown the XO sex the five of autosomes are simi- phase, pairs mechanism; Uttaris reveals the XY sys- lar in size. The course of meiosis (Fig. tem, which is more common in the Ly- 61b, is the same as in Oedancala dor- c) gaeidae. Nevertheless, the chromosome salis. in the — cytology of the species is as others, 62. Pachygrontha longiceps Stal. Pach- and the meiotic process (Figs. 64b, c) is more of ygrontha longiceps has two pairs quite orthodox. autosomes than other Pachygrontha spe- Teracriini. cies described. The previously spermato- — gonial metaphase of the species consists of 65. Opistholeptus indicus Slater. The of seven pairs of autosomes, an m-chromo- male diploid chromosome complement indicus consists of five some pair, and an X chromosome (Fig. Opistholeptus pairs Cytotaxonomy of Lygaeidae 753

Pachygronthinae b 1 TERACRIINI {•% ••••:?.# ft 1

DJ Opistholeptus indicus

t %

00 Pachyphlegyas modigliani

'$ li»*» Ml-I*

0/ Phlegyas abbreviates^

• Mb c • 1 }&• »» ft If

68 Stenophyella macreta

9 Heterogastrinae • • , I

09 Dinomachellus maculatus

• a t• D |• mm tlb • • • • vw i I i /U Dinomachus marshalli

_ a „ lib ||' ^'ii • •?• * I 'hi Vi •• 71 Heterogaster behrensii

meta- Fie. 65-71. Chromosomes of named species of Pachygronthinae and Heterogastrinae: a, spermatogonial phase; b, first metaphase; c, second metaphase. Scale = 10/im. 754 The University of Kansas Science Bulletin

the is of autosomes, an m-chromosome pair, and however, Y slightly smaller than the the others. The m-chromosomes are the XY sex pair (Fig. 65a). In spermato- of autosomes is smallest in the set. The mei- gonia! metaphase, one pair components otic is as in larger than the others and the remaining sequence (Fig. 67b, c) Opis- are indicus. four pairs and the X chromosome tholeptus is half — similar in size. The Y chromosome 68. Stenophyella macreta Horvath. twice as as the size of the X and large The male diploid chromosome comple- the m-chromosomes. ment of Stenophyella macreta consists of In meiosis, the X and Y chromosomes five pairs of autosomes, an m-chromosome in and an XY One of are positively heteropycnotic early pro- pair, pair (Fig. 68a). five autosome is than the phase and become isopycnotic by late dia- the pairs larger kinesis. They reveal nonhomologous as- others. The X chromosome is the same the sociation in the diffuse stage and in the size as the smaller autosomes, and Y is smaller than the X. The m-chromo- diplotene stage, separate from each other. somes are the smallest in the The five pairs of autosomes become evi- components set are a third the size of the Y. dent at the diplotene stage and pass into and a typical diakinesis. The m-chromosomes The course of meiosis is as in Opistho- the and are are unpaired during prophase leptus indicus except that in second meta- at the first meta- negatively heteropycnotic phase, the m-chromosome occupies the phase. center of the spindle. (Fig. 68b, c).

The course of meiosis (Fig. 65b, c) is as in Oedancala dorsahs except that at Heterogastrinae second metaphase, the m-chromosome lies Three genera and six species of the on the periphery of the spindle with the subfamily Heterogastrinae have been in- autosomes (Fig. 65c). vestigated cytologically. The chromosome 66. Pachyphlegyas modigliani (Lethier- number in Dinomachellus (three species) —The chromosome of ry). complement is 14 (12 + XY) and in Heterogaster (one the male of modigliani con- Pachyphlegyas species) and Masoas (two species) 16 (14 sists of five pairs of autosomes, a pair of + XY). The modal number of the sub- m-chromosomes, and an XY pair (Fig. family is uncertain. 66a). In the spermatogonial metaphase, The behavior of chromosomes during five pairs of autosomes and the X chro- meiosis in these species is quite orthodox. mosome are similar in size and the Y The X, Y and m take a central position chromosome is smaller than the X. The at both first and second metaphase. m-chromosome is a third the size of the 69. Dinomachellus maculatus Scudder Y and the smallest component in the set. — and D. sp. (GGES-23). The chromosome The course of the meiosis (Fig. 66b, c) is cytology of these two species of Dinoma- as in Opistholeptus indicus. chellus is the same. The male diploid 67. Phlegyas abbreviatus (Uhler).— chromosome complement consists of five Cytological study of Phlegyas abbreviatus pairs of autosomes, an m-chromosome pair, had been done by Montgomery (\90\b, and an XY sex pair (Fig. 69a). The five 1906). Our findings confirm his observa- pairs of autosomes comprise one large pair, tions. The spermatogonial metaphase con- three medium-sized pairs, and one small sists of five pairs of autosomes, an m-chro- The X chromosome is the same size mosome pair, and an XY sex pair (Fig. pair. as the medium-sized autosomes and the 67a). All the autosomes and the X and Y sex chromosomes are similar in size; Y is smaller than the small pair. The Cytotaxonomy of Lygaeidae 755

m-chromosomcs are the smallest compo- smallest components in the set, and are nents in the set. half the size of the Y. The meiotic se-

In meiosis, the X and Y chromosomes quence (Fig. 71b, c) is as in Dinoma- chellus maculatus, described. are positively heteropycnotic in the early previously and form a as- 72. Masoas prophase nonhomologous transvaaliensis— Distant and sociation at the diffuse stage. They sepa- M. sp. (GGES-22). The chromosome rate and are double structures composed complement in these two species of Ma- of two sister chromatids at the diplotene soas is the same. The spermatogonial stage. They become isopycnotic by late metaphase consists of six pairs of auto-

diakinesis. The autosomes become evi- somes, an m-chromosome pair, and an dent after the diffuse stage and pass into XY sex pair (Fig. 72a). Two of the six a typical diakinesis. They are associated autosome pairs are smaller than the other by one chiasma on each and the terminal- four. The X chromosome is equal in size ization of chiasmata is completed by the to the smaller autosomes, and the Y is prometaphase. The m-chromosomes are smaller than the X. The m-chromosomes unpaired during the prophase and are are the smallest components in the set, negatively heteropycnotic at metaphase I. and are half the size of the Y. The meiotic is as in Dinomachel- As the first metaphase is formed, five sequence (Fig. 72b-d) lus maculatus. autosomal tetrads orient on the periphery of a spindle as the X and Y dyads and the R h yparoch ro m in ae m-chromosome lie in the center of the as well as spindle (Fig. 69b). The first meiosis is Cytologically morphologi- the is equational for the sex chromosomes and cally, Rhyparochrominae heteroge- reductional for the m-chromosome. At the neous. It is the largest subfamily in the and contains half the in second metaphase, the XY pseudopair and Lygaeidae species the the m-chromosome lie in the center of a family. Of these, 142 species in 67 have been worked out ring formed by the autosomes (Fig. 69c). genera cytologically.

70. Dinomachus marshalli (Distant).— Plinthisini. The essential features of chromosome cy- In the tribe six of tology of Dinomachus marshalli are as in Plinthisini, species the are known Dinomachellus maculatus. The spermato- only genus cytologically. The chromosome number is 16 gonial metaphase consists of five pairs of (14 + a of m-chromosomes. autosomes, an m-chromosome pair, and XY), including pair However, Pfaler-Collander the X and Y sex chromosomes (Fig. 70a). (1941) report- ed 18 in the female and 9 at first The course of meiosis (Fig. 70b, c) is as diploid in Dinomachellus maculatus. metaphase of oogenesis in Plinthisus pu- sillus. She did not observe any males. 71. Heterogaster behrensii (Uhler).— From her result, we may assume that the The male diploid chromosome comple- chromosome complement of P. pusillus is ment of Heterogaster behrensii consists of 17 (14 + XiXi.Y) in the male. six pairs of autosomes, a pair of m-chro- The chromosome behavior in Plinthi- mosomes, and an XY sex pair (Fig. 71a). sus meiosis is usual at I. The autosome pairs are composed of one during metaphase the m-chromosome tends to take large, four medium, and one small pair. However, a with the autosomes The X chromosome belongs to the me- peripheral position at II. The XY lies dium-sized group of autosomes and the Y metaphase pseudopair in the center as usual. is slightly smaller than the small-sized autosomes. The m-chromosomes are the 73. Plinthisus compactus (Uhler), P. 756 The University of Kansas Science Bulletin

Heterogastrinae

• c d ; t •i '.jut •a? tit IL Masoas transvaahensis

Rhyparochrominae PLINTHISINI a • b • A c • • • s •

73 Plinthisus compactus

LETHAEINI #?•• a I . It'll 1 I #4 Cryphula nitens

a b §m I g I I tl'ltf

IJ Diniella nitida • t

a b

-•••• tVi ••V »••• '••' 76 Diniella sp. PDA- 44

I • 77 lamproceps sp. GGES-13

Fie. 72-77. Chromosomes of named species of Heterogastrinae and Rhyparochrominae: a, spermatogonia! meta- 10 phase; b, first metaphase; c, second metaphase. (Exception Fig. 72: c and d, second metaphase.) Scale = /im, Cytotaxonomy of Lycaeidae 757

P. P. a hollow while the X and Y longisetosus Barber, sp. —(U-120), sp. spindle, (E-23), and P. sp. (C-27). The chromo- dyads and the m-chromosome occupy the some cytology of these five species of center of the spindle (Fig. 73b). The first Plinthisus are the same. The male diploid division is reductional for the m-chromo- chromosome complement of these species some and equational for the sex chro- consists of six pairs of autosomes, a pair mosomes. As is usual in Heteroptera, the of m-chromosomes, and an XY sex pair second meiosis follows directly from the (Fig. 73a). In the spermatogonial meta- first without any resting period. At the phase, two of the six autosome pairs are second metaphase, the XY pseudopair lies in of slightly smaller than the others. Compara- the center a ring formed by the tive size differences of chromosomes in autosomes and the m-chromosome (Fig. these five species are given in Table 7. For 73c). example, in P. compactus, the X chromo- Leth aeini. some belongs to the medium-sized group of autosomes and the Y is half the size Eight genera and 14 species of the of the X. The m-chromosomes are the tribe Lethaeini are now known cytologi- smallest components in the set and are cally. The data so far available suggest about one-third the size of the Y. that the modal number of the tribe is 13

In meiosis, the X and Y chromosomes (12 + XO). Deviation of chromosome are positively heteropycnotic in the early number from 13 may be caused by frag- prophase and become isopycnotic by late mentation where numbers increase and by diakinesis. They are in nonhomologous fusion where they decrease. This tribe is association at the diffuse stage and sepa- characterized by a lack of the Y chromo- rate from each other in the diplotene some, probably lost during chromosome is also stage. At the diplotene stage they can be evolution. The Y chromosome resolved as double structures composed of lacking in the genus Poeantius of the two sister chromatids. The autosomes be- Rhyparochromini. Chromosome behavior is ortho- come evident right after the diffuse stage during meiosis in the tribe quite a central and pass into a typical diakinesis. They dox. The X and m take position are associated by one chiasma on each, at both metaphase I and metaphase II. and the terminalization of chiasmata is 74. Cryphula nitens Barber and C. the m- — completed by prometaphase. The trimaculata (Distant). These two species chromosomes are unpaired during the pro- of Cryphula are the same in chromosome and are at phase negatively heteropycnotic cytology. The spermatogonial metaphase the first maintain this metaphase. They consists of four pairs of autosomes, an m- condition until the of meiosis. completion chromosome pair, and the sole X chromo- As the first metaphase is formed, six some (Fig. 74a). One of four autosome autosomal tetrads lie on the periphery of pairs is larger than the others. The X

Table 7. Relative size differences of chromosome complements in the genus Plinthisus (Rhy- parochrominae) (EL, extra large; L, large; M, medium-sized; S, small).

No. autosome paii

Species P. compactus (Uhler) P. longisetosus Barber P. sp. (U-120) P. sp. (E-23) P. sp. (C-27) Bulletin 758 The University of Kansas Science

ula nitens. In the chromosome is smaller than any autosome as in Cryph anaphase II, and the m-chromosomes, the smallest com- X moves to one pole with one set of auto- some halves ponents in the set, are easily distinguished. (Fig. 76d). is — In meiosis, the X chromosome posi- 77. Lamproceps sp. (GGES-13). The in the tively heteropycnotic early prophase, spermatogonial metaphase of this Lam- of two of and is a double structure composed proceps species consists of five pairs diffuse sister chromatids at the stage. By autosomes, an m-chromosomes pair, and late diakinesis it has become isopycnotic. an X chromosome (Fig. 77a). One pair immedi- The autosomes become evident of autosomes is larger than the others and and into ately after the diffuse stage pass the X chromosome is smaller than the the a typical diakinesis. The m-chromosomes autosomes. The m-chromosomes are are unpaired during the prophase and are smallest components in the set. The negatively heteropycnotic at metaphase I. course of meiosis (Fig. 77b, c) is as in tetrads ula nitens. In metaphase I, four autosomal Cryph while the and — lie on the periphery, X dyad 78. Near Lamproceps sp. (GGES-21). the center of a the m-chromosomes occupy The male diploid chromosome comple- ring formed by the autosomes (Fig. 74b). ment of this species near Lamproceps the chromosome a Again at metaphase II, X consists of five pairs of autosomes, pair and the m-chromosome lie in the center of m-chromosomes, and an X chromo- the of a ring formed by autosomes (Fig. some (Fig. 78a). One of the five auto- others 74c). some pairs is larger than the and is about to the 75. Diniella nitida (Reuter), D. sp. the X chromosome equal and D. small-sized autosomes. The m-chromo- (GGES-18), D. sp. (GGES-19), — somes are the smallest in the sp. (GGES-20). The chromosome cytol- component are set. The course of meiosis 78b, is ogy of these four species of Diniella (Fig. c) the same. The spermatogonial metaphase as in Crypluila nitens. consists of five pairs of autosomes, an m- 79. Lethaeus barberi Slater.—The chro- chromosome barberi is chromosome pair, and an X mosome cytology of Lethaeus of (Fig. 75a). In all four species, one pair similar to that of Crypluila nitens in every autosomes is larger than the others and essential feature. The spermatogonial met- is the size of the the X chromosome half aphase consists of four pairs of autosomes, small-sized autosomes. The m-chromo- an m-chromosome pair, and the X chro- in the four auto- somes are the smallest components mosome (Fig. 79a). One of the set. of these than the The meiotic sequence spe- some pairs is quite a bit larger nitens. in cies (Fig. 75b, c) is as in Crypluila others. The X chromosome is similar size to the medium-sized autosomes and 76. Diniella sp. (PDA-44).—The male be from them. The diploid chromosome complement in this cannot distinguished of m-chromosomes are the smallest species of Diniella consists of six pairs compo- of meiosis autosomes, one more than in other Dini- nent in the set. The course is as in ula nitens. ella, an m-chromosome pair, and the sole (Fig. 79b, c) Cryph This X chromosome (Fig. 76a). The autosome 80. Lethaeus sp. (GGES-11).— spe- of pairs are similar in size and the X chro- cies of Lethaeus has one more pair mosome is smaller than the autosomes. autosomes than L. barberi, previously de- The m-chromosomes are one-third the size scribed. The spermatogonial metaphase a of the X and are the smallest components consists of five pairs of autosomes, pair in the spermatogonial metaphase set. of m-chromosomes, and the sole X chro- All the autosomes The course of meiosis (Fig. 76b, c) is mosome (Fig. 80a). Cytotaxonomy of Lygaeidae 759 Rhyparochrominae # LETHAEINI

1 ll /0 near Lamproceps sp GGES-21

• I I • f.* I • J ••• ^ /" Lethaeus barberi

m - ~* lib |c A d

••• II • • — 80 Lethaeus sp. - GGES-11

Ol Neolethaeus dallasi

$& |l|:tlt *»•««

82 Orbelli s sp.

» « « 83 Xestocoris nitens'»

Fig. 78-83. Chromosomes of named species of Rhyparochrominae: a, spermatogonia! metaphase; b, first meta-

phase; c, second metaphase. {Exception Fig. 80: c and d, second metaphase.) Scale = 10 /im. 760 The University of Kansas Science Bulletin

and the X chromosome are similar in size the tribe Ozophorini have been investi- and the m-chromosomes are much smaller. gated cytologically. One has a chromo- The meiotic sequence (Fig. 80b-d) is as in some number of 16 (14 + XY), and the Cryphula nitens. other, Prosomoeus brunneus, which was observed 81. Neolethaeus dallasi (Scott).—The by Muramoto (1973), 14 (12 + need male diploid chromosome complement of XY). We more information to dis- cuss the characteristic Neolethaeus dallasi consists of five pairs chromosome cytol- of the tribe. of autosomes, a pair of m-chromosomes, ogy and an X chromosome In the — (Fig. 81a). 84. Migdilybs jurcijer Hesse. The dip- spermatogonial metaphase, all the auto- loid chromosome complement of Mig- somes and the chromosome are similar X dilybs jurcijer consists of six pairs of auto- in size. The m-chromosomes are the small- somes, an m-chromosome pair, and the X est in the set. component and Y sex chromosomes (Fig. 84a). All six of autosomes are similar The course of meiosis (Fig. 81b, c) is pairs in size. as in Cryphula nitens. As at both meta- The X is the same size as the autosomes and the is phases, five autosomal tetrads orient on Y slightly smaller than the X. The the periphery of a spindle while the X and m-chromosomes are the smallest com- the m-chromosome lie in the center. ponents in the set.

— The course of meiosis is orthodox. 82. Orbellis sp. The spermatogonial quite At six autosomal tetrads ar- metaphase of this species of Orbellis con- metaphase I, themselves the of sists of five pairs of autosomes, an m- range on periphery a while the and chromosome pair, and the X chromosome spindle X Y dyads and the locate in the center of a (Fig. 82a). Of the five autosome pairs, m-pair ring one is large, one is medium-sized, and formed by the autosomes (Fig. 84b). As three are small. The X chromosome be- is usual, the XY pseudopair and the m- longs to the small-sized group of auto- chromosome lie in the center of a ring somes. The m-chromosomes are the small- formed by the autosomes at second meta- est components in the set. The chromo- phase (Fig. 84c). some cytology and the meiotic sequence of Antillocorini. the species (Fig. 82b, c) is as in Cryphula described nitens, previously. Four genera and six species of the 83. Xestocoris nitens Van Duzee.—The tribe Antillocorini have been studied cyto- spermatogonial metaphase of Xestocoris logically. The modal number of the tribe nitens to be 14 -4- a consists of five pairs of autosomes, appears (12 XY) including of m-chromosomes. In an m-chromosome pair, and the sole X pair Tropistethus chromosome (Fig. 83a). One of the auto- holosericus, Pfaler-Collander (1941) could not either some pairs is larger than the others. The clearly distinguish the presence X chromosome is equal in size to the or absence of the m-chromosomes. How- smaller autosomes, and the m-chromo- ever, her Figure 19e suggests the presence somes are the smallest components in the of the m-chromosomes. Unfortunately, we set. did not have an to observe The meiotic sequence (Fig. 83b, c) is opportunity as in Cryphula nitens, with the X and the the species. m-chromosome lying in the center of the In both Antillocoris and Cligenes, chro- at both spindle metaphases. mosome cytology during meiosis is a little

unusual. At metaphase I, the X and Y Ozophorini. locate in the center, while the m-chromo- two Only genera and two species of some tends to locate on the periphery with Cytotaxonomy of Lygaeidae 761

Rhyparochrominae • »• •• OZOPHORINI % -' f I it 84 Migdilybs furcifer

ANTILLOCORINI b ° •*• a • • t • .' Sii* i** i • t

tit§ I OJ Antillocoris minutus

a b ##M I • c fit • • 00 Microcoris sexnotatus

a b t t | ' « •sis? »u« Hi v 0/ Cligenes aethiops

• 762 The University of Kansas Science Bulletin

the autosomes. Metaphase II is quite or- and the X chromosome are similar in size thodox, with the XY pseudopair and the and the Y chromosome is smaller than m arranging in the center. the X. The m-chromosomes are the small- est in the set. 85. Antillocoris minutus (Bergroth).— components The course of meiosis is as in Antillocoris The male diploid chromosome comple- (Fig. 86b, c) ment of Antillocoris minutus consists of minutus. five of a of m-chro- 87. Distant and C. pairs autosomes, pair Cligenes —aethiops sp. mosomes, and an XY sex pair (Fig. 85a). (near ashanti). The male diploid chro- In the all the of spermatogonia! metaphase, mosome complement these two species of autosomes and the X chromosome are Cligenes consists of five pairs of auto- in size is similar and the Y chromosome somes, an m-chromosome pair, and the smaller than the X. The m-chromosomes X and Y sex chromosomes (Fig. 87a). are the smallest components in the set. One of the five pairs of autosomes is than the others. In meiosis, the X and Y chromosomes larger The m-pair and the Y are are positively heteropycnotic in the early chromosome, being smaller, from the but prophase and become isopycnotic by late easily distinguishable others, the X is not in diakinesis. They are in nonhomologous recognizable the spermato- because it is the same association at the diffuse stage and main- gonial metaphase size as the other autosomes. The meiotic tain this status until the early diplotene 87b, is as in Antillocoris stage. In the late diplotene, they separate sequence (Fig. c) minutus in from each other and can be resolved as every essential feature. double structures. The tetrad nature of 88. Cligenes subcavicola Scudder.— Cli- subcavicola the autosomes becomes evident right after genes has one more pair of than the diffuse stage, and they pass into a autosomes C. aethiops, previously de- typical diakinesis. The m-chromosomes scribed. The spermatogonial metaphase are unpaired during the prophase and are consists of six pairs of autosomes, an m- negatively heteropycnotic at the first meta- chromosome pair, and the X and Y sex phase. chromosomes (Fig. 88a). The six pairs of autosomes decrease in As the first metaphase is formed, there gradually size, and there are no autosomes are eight chromosome entities: five auto- clearly large as in C. somal tetrads, an m-chromosome tetrad, aethiops. course of and the X and Y dyads (Fig. 85b). At The meiosis in the species the first metaphase, the autosomes and the (Fig. 88b, c) is quite similar to that of m-chromosome are usually located on the Cligenes aethiops. At metaphase I, six periphery while the X and Y chromo- pairs of autosomes lie on the periphery of a the somes occupy the central position. The spindle while m-chromosomes and peripheral position of the m-chromosome the X and Y dyads are usually located in at first metaphase is very unusual. At the the center (Fig. 88b). The arrangement second metaphase, the autosomes lie on of the m-chromosome at the first meta- the periphery of a spindle but the XY phase is different than in other antilloco- pseudopair and the m-chromosome oc- rines. the center cupy of the spindle (Fig. 85c). Targaremini. 86. Microcoris sexnotatus (Bergroth).— The one spermatogonial metaphase in Micro- Only genus and species has been coris sexnotatus observed. Further of consists of five pairs of cytological study an other autosomes, m-chromosome pair, and an species in this tribe is needed. XY sex pair (Fig. 86a). All the autosomes 89. Targarema stall B.-White—The Cytotaxonomy of Lygaeidae 763

spermatogonia! metaphase of Targarema the multiple sex chromosome mechanism. stall consists of seven pairs of autosomes The distribution pattern of chromosome and an XY sex pair (Fig. 88a). The auto- numbers in the tribe is given in Figure somes and X chromosome are similar in 135.

size, and the Y chromosome, the smallest Chromosome behavior during meiosis in the tribe is lor component in the set, is easily distinguish- Drymini quite normal able. So far, no m-chromosome has been the Lygaeidae. At both first and second the take observed in this species. This status is metaphases, X, Y, and m a cen- very unusual in the Rhyparochrominae. tral position in a hollow spindle. In meiosis, the X and Y chromosomes 90. Appolonius quadratus Scudder.— of are positively heteropycnotic and become The spermatogonia! metaphase Ap- consists of seven isopycnotic by late diakinesis. They are in polonius quadratus pairs nonhomologous association and can be re- of autosomes, an m-chromosome pair, and solved as double structures composed of the X .and Y sex chromosomes (Fig. 90a). are two sister chromatids in the diffuse stage. Seven pairs of autosomes and the X is half as In the diplotene stage they separate from similar in size. The Y about each other. The autosomes, whose tetrad large as the other chromosomes. The m- nature becomes evident immediately after pair is the smallest component in the set. the diffuse stage, are associated by one In meiosis, the X and Y chromosomes each. The terminalization of chiasma on are positively heteropycnotic and become is the chiasmata completed by prometa- isopycnotic by late diakinesis. They are in phase. nonhomologous association at the diffuse As the first metaphase is formed, usu- stage and separate in the early diplotene At the can be ally the seven autosomal tetrads and the stage. diplotene stage, they X dyad lie on the periphery of a spindle resolved as double structures. The auto- while the Y chromosome occupies the cen- somes become evident right after the dif- are un- ter of the spindle (Fig. 89b). This ar- fuse stage. The m-chromosomes rangement at metaphase I for the X chro- paired during the prophase and are nega- mosome is very unusual. At the second tively heteropycnotic at the metaphase. metaphase, the XY pseudopair always lies At the first metaphase, seven autosomal auto- in the center of a ring formed by tetrads orient on the periphery of a spin- somes (Fig. 89c). dle, while the X and Y dyads and the m-chromosomes lie in the center of the mini. Dry spindle (Fig. 90b). As is usual, the first division is reductional for autosomes and Nine genera and 25 species of the tribe the m-chromosomes and equational for Drymini are now known cytologically. the second meta- The data so far available indicate that the the sex chromosomes. At the XY and the modal number of the tribe is 20 (18 + phase, again pseudopair m-chromosome lie in the center of a ring XY), including a pair of m-chromosomes. There are a few deviations from the mo- formed by autosomal dyads (Fig. 90c). 91. us units —The male dal number. One species shows 18 (16 + Drym (Say). of XY) and three show 16 (14 + XY). diploid chromosome complement Dry- These deviations from the modal number mus units is eight pairs of autosomes, an and an XY sex may have occurred by the fusion of auto- m-chromosome pair, pair and the somes as in pentatomids (Schrader, 1947) (Fig. 91a). All the autosomes X and cimicids (Ueshima, 1966b). Thylo- and Y chromosomes are similar in size; chromus reveals 21 chromosomes due to the m-chromosomes are much smaller. 764 The University of Kansas Science Bulletin

Rhyparochrommae • A DRYMINI

90 Appolonius quadratus

a | t g b c

• • 9131 „Drymus unus

• • 9 M a f f • b 9 c •••* it •• 92 Eremocoris dimidiatus

a It ' .!». c • ;

93 Scolopostethus pacificus

C

94 Stilbocoris sp. PDA-34

b a A t ft | • 7#

SO Thylochromus nitidulus

first meta- Fig. 90-95. Chromosomes of named species of Rhyparochrominae: a, spermatogonial metaphase; b,

phase; c, second metaphase. Scale = 10 yum. Cytotaxonomy of Lygaeidae 765

The course of meiosis (Fig. 91b, c) is as in The male diploid chromosome comple- Appolonius qaadratus, previously de- ment of Thylochromus nitidulus consists scribed. of eight pairs of autosomes, an m-chromo- 92. Eremocoris dimidiatus Van Duzee, some pair, and the X1X2Y multiple sex All the m-chromo- E. sp. near borealis (Dallas), E. inqiiiliniis pair (Fig. 95a). except somes decrease in size from Van Duzee, and E. opticus Van Duzee.— gradually to small. The m-chromosomes are These four species of Eremocoris are large smaller than other chromosomes in the same in their chromosome cytology. any the The spermatogonia! metaphase consists of spermatogonial metaphase plate. eight pairs of autosomes, an m-chromo- The course of meiosis (Fig. 95b, c) is some pair, and an XY sex pair (Fig. 92a). similar to that of Appolonius quadratus. All except the m-chromosomes gradually The Xi, X2, and Y sex chromosomes are decrease in size from large to small. The positively heteropycnotic in the early pro- m-chromosomes are the smallest compo- phase and become isopycnotic by late dia- nents in the set and are easily distin- kinesis. As the result of the second divi- guished from other chromosomes. The sion, there are two types of spermatids: meiotic sequence of these species (Fig. 8 + m + X1X2 and 8 + m + Y. 92b, c) is as in Appolonius quadratus. 93. Barber and Stygnocorini. Scolopostethus— pacificus S. thomsoni Reuter. The chromosome cy- Two genera and five species of the tology of these two species of Scoloposte- tribe Stygnocorini have been studied. In thus is the same. The spermatogonial Stygnocoris, three species have 16 (14 -f- metaphase consists of eight pairs of auto- XY), but S. rusticus reveals 18 (16 + XY) somes, an m-chromosome pair, and an XY (see Fig. 96). This increased chromosome about sex pair (Fig. 93a). In both species, two number may have been brought of the eight autosome pairs are slightly either by fragmentation or by duplication smaller than the others. The X chromo- of one pair of autosomes during chromo- some belongs to the medium-sized group some evolution. Chromosome cytology of autosomes and the Y is smaller than during meiosis in the tribe is quite ortho- the X. The m-chromosomes are the small- dox. est in the set. course of — components The 96. Stygnocoris rusticus (Fallen). The meiosis is as in (Fig. 93b, c) Appolonius chromosome cytology of Stygnocoris rusti- quadratus. cus has been studied by Pfaler-Collander confirm her observa- 94. Stilbocoris sp. (PDA-34), S. sp. (1941). Our findings con- (GGES-14), S. sp. (GGES-15), and S. sp. tions. The spermatogonial metaphase — of an m- (GGES-16). These four species of Stil- sists of seven pairs autosomes, bocoris are the same in their chromosome chromosome pair, and an XY sex pair m-chromosomes cytology in every essential feature. The (Fig. 96a). All except the spermatogonial metaphase consists of eight are similar in size. The m-chromosomes than the others and are pairs of autosomes, an m-chromosome pair, are much smaller and an XY pair (Fig. 94a). All except easily distinguished. the m-chromosomes are similar in size. The course of meiosis is as in Drymus The m-chromosomes are the smallest com- unus. At metaphase I, seven autosomal meiotic ponents in the set. The process bivalents lie on the periphery of a hollow is as in (Fig. 94b, c) Appolonius quad- spindle while the X and Y univalents and ratus. the m-chromosomes orient in the center of — at meta- 95. Thylochromus nitidulus Barber. the spindle (Fig. 96b). Again of Kansas Science Bulletin 766 The University m Rhyparochrominae • fm• •W fi Iff• 9* STYGNOCORINI • • t • y.A • t ;

30 Stygnocoriygnocons rusticus CLERADINI |l a b * .'.•A • |,| i • • V.V •»•§• • •»• 97 Clerada apicicornis MYODOCHINI

# • % a I .) m « f » • #;J; tut I

98 Afrovertanus elongatus

t II* | 99 Carpilis consimilis

*»• • ## a • A_ bh . c

• •• , •• 1 UU Cnemodus albimaculus

b » c *** a I• • i• - r

' 9* .'vt 101 Exptochiomera dissimilis

lib . «t •«& •is. • i

lU* Heraeus pacificus

first meta- Fig. 96-102. Chromosomes of named species of Rhyparochrominae: a, spermatogonia! metaphase; b, phase; c, second metaphase. Scale = 10 /mi. Cytotaxonomy of Lygaeidae 767

the and the is phase II, XY pseudopair m- Further study needed taxonomically as chromosome lie in the center of a well as ring cytologically on the species. formed the autosomes In the by (Fig. 96c). genus Paromius, four species show 14 (12 + XY) chromosomes, while Cleradini. one species, P. pallidus, reveals 12 (10 + one and one of the Only genus species XY) chromosomes. To date, cytological tribe is Cleradini known. This species, data suggest that the modal number of Clerada shows the the is 16 apicicornis, highest Myodochini (14 + XY). If so, chromosome 24 number, (22 + XY), so then 12 chromosomes in Paromius pallidas far observed in the Rhyparochrominae. might be derived by spontaneous fusion.

In P. its, the of autosomes The chromosome cytology of the spe- pallid largest pair cies is usual at first division, but the m- is much larger than the largest pair in other of Paromius 106 chromosome tends to arrange on the pe- species (see Figs. and 107. This riphery at the second metaphase. may indicate that spon- — taneous fusion has taken 97. Clerada apicicornis Signoret. The place. Chromosome behavior meiosis spermatogonia! metaphase of Clerada api- during in the tribe is as usual at the first division. cicornis consists of ten pairs of autosomes, at second the an m-chromosome pair, and an XY sex However, metaphase, m- chromosome tends to locate pair (Fig. 97a), the highest chromosome on the periph- number in the Rhyparochrominae. The ery with the autosomes, while the XY lies in the chromosomes gradually decrease in size pseudopair center as usual. from large to small. The m-chromosomes, The distribution pattern of chromo- the smallest components in the set, are some numbers in Myodochini is given in readily recognized, but the X and Y chro- Figure 136. mosomes are not distinguishable. 98. Afrovertanus elongatus Scudder.— The course of meiosis (Fig. 97b, c) is The male diploid chromosome comple- essentially as in Drymus units except that ment of Afrovertanus elongatus consists the m-chromosome lies on the periphery of five pairs of autosomes, a pair of m- of a hollow spindle in second metaphase. chromosomes, and the X and Y sex chro- mosomes (Fig. 98a). In the spermato- Myodochini. gonial metaphase, all the autosomes and Sixteen genera and 43 species have been the X chromosome are similar in size. investigated. Of these, the great majority The Y chromosome is smaller than the show 16 (14 + XY) chromosomes, but X. The m-chromosomes are the smallest some show 14 (12 4* XY). In the genus components in the set and are half the Pachybrachius, four of the 18 species have size of the Y. 14 the re- (12 + XY) chromosomes, and In meiosis, the X and Y chromosomes 14 have 16 maining species (14 + XY). are positively heteropycnotic in the early Two chromosomes have fused to may prophase and become isopycnotic by late form one in these four their species during diakinesis. They are in nonhomologous chromosome evolution. association at the diffuse stage and are In Pachybrachius lateralis, two chromo- separate from each other in the diplotene some types are found in Japan. The speci- stage, when they can be resolved as double mens which show 16 (14 -f- XY) are from structures. The autosomes become evident Kyushu, while Takenouchi and Mura- immediately after the diffuse stage and moto (1967) reported 14 (12 + XY) chro- pass into a typical diakinesis. The m- mosomes in specimens from Hokkaido. chromosomes are unpaired during the pro- 768 The University of Kansas Science Bulletin

phase and are negatively heteropycnotic at about three times as large as the m-chro- first metaphase. mosome. The meiotic process (Fig. 101b, is as in As the first metaphase is formed, five c) Afrovertanus elongatus. autosomal tetrads orient on the periphery 102. Heraeus pacifrcus Barber.—The of a spindle but the X and Y dyads and spermatogonial metaphase of Heraeus pa- the m-chromosome lie in the center of the cificus consists of six pairs of autosomes, spindle (Fig. 98b). The first division is a pair of m-chromosomes, and an XY sex reductional for the m-chromosome and pair (Fig. 102a). All except the m-chro- equational for the sex chromosomes. At mosomes gradually decrease in size from the second metaphase, the autosomes and large to small. The m-chromosomes are the m-chromosome lie on the periphery smallest and are easily distinguishable and the XY pseudopair occupies the cen- from other chromosomes. The process of ter of the spindle (Fig. 98c). meiosis (Fig. 102b, c) is as in Afrover- tanus 99. Carpilis consimilis Barber.—The elongatus. spermatogonial metaphase of Carpilis con- 103. Ligyrocoris diffusus (Uhler), L. similis consists of six of and L. pairs autosomes, latimarginatus— Barber, litigiosus a pair of m-chromosomes, and an XY sex (Stal). These three species of Ligyrocoris pair (Fig. 99a). Two of the six pairs of are the same in their chromosome cytol- autosomes are larger than the others. The ogy. The spermatogonial metaphase con- X chromosome is equal to the small-sized sists of six pairs of autosomes, an m-chro- group of autosomes and the Y is half the mosome pair, and an XY sex pair (Fig. size of the X. The m-chromosomes are a 103a). All except the m-chromosome grad- third as large as the Y and the smallest ually decrease in size from large to small. component in the set. The course of meio- The m-chromosomes are the smallest com- sis (Fig. 99b, c) is as in Afrovertanus ponents in the set. The course of meiosis elongatus. (Fig. 103b, c) is as in Afrovertanus elon- 100. Cnemodus albimaculus and gatus. — Berg C. mavortius (Say). The chromosome cy- 104. Pachybrachius albocinctus Barber of these two of Cnemodus and other in the tology species — species genus Pachybrach- is the same. The spermatogonial meta- ius. The chromosome cytology of the fol- phase consists of six pairs of autosomes, lowing observed species is the same: Pach- a pair of m-chromosomes, and an XY sex ybrachius albocintus Barber, P. bilobatus pair (Fig. 100a). All the autosomes and (Say), P. insularis (Barber), P. lateralis the X and Y chromosomes are similar in (Scott), P. limbatus (Stal), P. nesovinctus size. The m-chromosome is the smallest Ashlock, P. nietneri (Dohrn), P. vinctus component in the set. The meiotic se- (Say), P. sp. (PDA-46), P. sp. (GGES-8), quence (Fig. 100b, c) is as in Afrover- P. sp. (GGES-9), P. sp. (GGES-10), and tanus elongatus. P. sp. (MLY-2). 101. Exptochiomera dissimilis Barber.— The spermatogonial metaphase consists The male diploid chromosome comple- of six pairs of autosomes, a pair of m- ment of Exptochiomera dissimilis consists chromosomes, and an XY sex pair (Fig. of six pairs of autosomes, an m-chromo- 104a). In all the species, one of the six some pair, and an XY sex pair (Fig. 101a). autosome pairs is larger than the others. In the spermatogonial metaphase, the au- Relative size differences of chromosome tosomes and the X chromosome gradually complements are given in Table 8. For decrease in size from large to small. The instance, in P. albocinctus, the X chromo-

Y chromosome is smaller than the X and some is slightly smaller than the medium- Cytotaxonomy of Lygaeidae 769

Rhyparochrominae a C MYODOCHINI ,'•••• • ••: I ft I

103 Ligyrocoris diffusus

™ 104 Pachybrachius albocinctus

#S»a • • b

: t 105 Pachybrachius pacificus

• b • i» $ 106 Paromius apicatus

% b

## * t " 107 Paromius pallidus see text

a c • * « #•.:. ! .

108 Pseudocnemodus canadensis

Fig. 103-108. Chromosomes of named species of Rhyparochrominae: a, spermatogonial metaphase; b, first meta- phase; c, second metaphase. Scale = 10 /xm. 770 The University of Kansas Science Bulletin sized autosomes and is twice as large as chromosome cytology. The male diploid the Y. The m-chromosomes are about one- chromosome complement consists of five third the size of the Y. The meiotic se- pairs of autosomes, a pair of m-chromo- quence (Fig. 104b, c) is as in Afrover- somes, and an XY sex pair (Fig. 106a). tanus elongatus. Two of the five autosome pairs are larger 105. Pachybrachius pacificus (Stal), P. than the others. The X chromosome is basalts (Dallas), P. capicola (Stal), and P. equal in size to the small-sized autosomes inconspicuus (Dallas).—The chromosome and the Y is smaller than the X. The m- cytology of these four species of Pachy- chromosomes are the smallest components brachius is the same, but they differ from in the set. The meiotic process (Fig. 106b, other Pachybrachius species described pre- c) is as in Afrovertanus elongatus. The 107. Paromius viously. spermatogonial metaphase — pallidus (Montrouzier). consists of five pairs of autosomes, a pair Paromius pallidus has one less pair of of m-chromosomes, and an XY sex pair autosomes than the other Paromius de- (Fig. 105a). One of the five autosome scribed previously. Malipatel (1978) has pairs is larger than the others. The X synonymized P. pallidus with P. gracilis, chromosome is equal in size to the me- but they are treated separately here be- dium-sized autosomes and the Y is smaller cause of the difference in chromosome than the X. The m-chromosomes are the complement. The spermatogonial meta- smallest components in the set and are phase consists of four pairs of autosomes, easily distinguished. Relative size differ- a pair of m-chromosomes, and the X and ences of chromosome complements in these Y sex chromosomes (Fig. 107a). Two four species are summarized in Table 8. pairs of autosomes are larger than the The course of meiosis (Fig. 105b, c) is as other two. The X chromosome is equal in Afrovertanus elongatus. in size to the small-sized group of auto- 106. Paromius apicatus (Stal), P. gra- somes and is larger than the Y. The m- cilis P. and chromosomes are the smallest (Rambur), longulus— (Dallas), components P. paraclypeatus Scudder. These four spe- in the set. The course of meiosis (Fig. cies of Paromius are the same in their 107b, c) is as in Afrovertanus elongatus.

Table 8. Relative size differences of chromosome complements in the genus Pachybrachius (Rhyparochrominae) (EL, extra large; L, large; M, medium-sized; S, small). Sex

No. autosome pairs chromosomes

Species EL M

P. albocinctus Barber ... P. basalts (Dallas) P. bilobatus (Say) P. capicola (Stal) P. inconspicuus (Dallas) P. insularis (Barber) P. lateralis (Scott) P. hmbatus (Stal)

P. nesovinctus Ashlock .

P. pacificus (Stal) P. nietneri (Dohrn) P. vinctus (Say) P. sp. (PDA-46) P. sp. (GGES-8) P. sp. (GGES-9) P. sp. (GGES-10) P. sp. (MLY-2) Cytotaxonomy of Lygaeidak 771

108. Pseudocnemodus canadensis (Pro mosomes are the smallest components in — set. of vancher). The spermatogonia! metaphase the The course meiosis (Fig. 111b, of Pseudocnemodus canadensis consists of c) is as in Ajrovertanus elongatus. six of an m-chromosome pairs autosomes, 112. Stigmatonotum capucinum (Stal). sex All pair, and an XY pair (Fig. 108a). —The chromosome cytology of Stigmato- but the m-chromosome are similar in size. notum capucinum is as in Sphaerobius to the me- The X chromosome belongs insignis, previously described. The sper- of autosomes and is dium-sized group matogonial metaphase consists of six pairs the Y. m-chromosomes larger than The of autosomes, an m-chromosome pair, and smallest in the set. are the components the X and Y sex pair (Fig. 112a). The The meiotic sequence (Fig. 108b, c) is as meiotic sequence and the behavior of chro- in Ajrovertanus elongatus. mosomes during meiosis (Fig. 112b, c) is 109. Ptochiomera nodosa —The as in Say. Sphaerobius insignis. — male diploid chromosome complement 113. Togo hemipterus (Scott). The an m- consists of six pairs of autosomes, spermatogonial metaphase of Togo hemip- an sex chromosome pair, and XY pair terus consists of six pairs of autosomes, In the meta- (Fig. 109a). spermatogonial an m-chromosome pair, and the X and Y the are phase, all except m-chromosomes sex chromosomes (Fig. 113a). All except similar in size. The m-chromosomes are the m-chromosome are similar in size. The the smallest components in the set and are m-chromosomes are the smallest compo- easily recognized. The meiotic process nents in the set. The meiotic process (Fig. is as in elon- (Fig. 109b, c) Ajrovertanus 113b, c) is as in Sphaerobius insignis. gatus. 114. Zeridonius costalis (Van Duzee). 110. Remaudiereana —The male chromosome — nigriceps (Dallas) diploid comple- and R. sp. (MLY-3). These two species ment in Zeridonius costalis consists of six of Remaudiereana are the same in their pairs of autosomes, an m-chromosome pair, the chromosome cytology. The spermatogo- and an XY sex pair (Fig. 114a). In of five of nial metaphase consists pairs spermatogonial metaphase, all the auto- autosomes, a pair of m-chromosomes, and somes and the X chromosome are similar an XY sex pair (Fig. 110a). One of the in size. The Y chromosome is smaller five autosome pairs is larger than the than the X and much larger than the m- others. The X chromosome is equal in chromosomes. The meiotic sequence (Fig. and is size to the medium-sized autosomes 114b, c) is as in Sphaerobius insignis. about twice as large as the Y. The m- chromosomes are much smaller than the Udeocorini. Y and are the smallest in the — components 115. Serranegra sp. The chromosome set. The course of meiosis 110b, c) (Fig. cytology of this species of Serranegra is is as in Ajrovertanus elongatus. The — the same as in Paromius apicatus. 111. Sphaerobius insignis (Uhler). spermatogonial metaphase complement is chromosome The male diploid comple- five pairs of autosomes, an m-chromosome of consists of ment Sphaerobius insignis pair, and the X and Y sex chromosomes a of m-chro- of auto- six pairs of autosomes, pair (Fig. 115a). One of the five pairs sex mosomes, and an XY pair (Fig. Ilia). somes is larger than the others. The X In the spermatogonial metaphase, all the belongs to the medium-sized group of autosomes are similar in size. The X autosomes and is not distinguishable from

chromosome is similar to the autosomes in the autosomes. The m-chromosome is the smallest in the set and is half size but larger than the Y. The m-chro- component 772 The University of Kansas Science Bulletin

m , f « c Rhyparochrominae MYODOCHINI

109 Ptochiomera nodosa

I b I . c • f

I1Q Remaudiereana nigriceps

a b c M t •: aft Sphaerobius insignis

• I • - I •

•• • f 112 Stigmatonotum capucinum

in ** »• I I J Togo hemipterus

114 Zeridonius costalis

meta- Fig. 109-114. Chromosomes of named species of Rhyparochrominae: a, spermatogonia! metaphase; b, first phase; c, second metaphase. Scale =: 10 fim. Cytotaxonomy of Lygaeidae 773 as large as the Y. The meiotic sequence Peritrechus and Poeantius, the m lies in (Fig. 115b, c) is quite orthodox. the center of a spindle with the sex chro- mosomes at first metaphase and tends to Rhyparochromini. arrange on the periphery with the auto- the Fourteen genera and 28 species in the somes at second metaphase (see Figs. tribe Rhyparochromini have been cytologi- 124 and 126). 116. nitidus — cally investigated. This tribe is a rather Anepsiodes Reuter. The heterogeneous group cytologically. Fifteen male diploid chromosome complement of nitidus consists of species show 14 (12 + XY) chromosomes Anepsiodes five pairs of and seven show 12 (10 + XY) chromo- autosomes, an m-chromosome pair, and somes. In addition, Graphoraglius novitus an XY sex pair (Fig. 116a). In the sper- reveals 10 (8 + XY) chromosomes, the matogonial metaphase, all the autosomes lowest number in the whole Lygaeidae. and the X chromosome are similar in size. The three species of Poeantius so far stud- The Y chromosome is smaller than the ied lack the Y chromosome, and Grapto- X and larger than the m-chromosomes. peltus japonicus carries multiple X chro- In meiosis, the X and Y chromosomes mosomes. are positively heteropycnotic in the early Interestingly, Parshad (1957£) reported prophase and become isopycnotic by late that the m-chromosomes of Lachnesthus diakinesis. They are in nonhomologous singalensis were equational at the first di- association at the diffuse stage and are vision and reductional at the second. If separate in the diplotene stage. At the true, this is the only case of such behavior diplotene stage, they are double structures of the m-chromosomes in the whole fam- composed of two sister chromatids. The autosomes become evident after the ily. However, he did not observe the right detailed behavior of the m-chromosomes, diffuse stage and pass into a typical dia- and his drawings seem to show that the kinesis. The m-chromosomes are unpaired m-chromosomes are already double struc- during the prophase and are negatively tures and positively heteropycnotic at early heteropycnotic at metaphase I. diakinesis. According to our observations, As metaphase I is formed, five auto- not het- the m-chromosomes are positively somal tetrads locate on the periphery of a and are eropycnotic during prophase, they hollow spindle while the X and Y dyads negatively heteropycnotic at metaphase I and the m-chromosome orient in the cen- and II. does not mention He negative ter of the spindle (Fig. 116b). The first first or second heteropycnosis at either division is equational for the sex chromo- metaphase. Moreover, he did not draw somes. The second meiosis follows direct- or describe the side view of anaphase I, ly after the first without any resting stage. which is the most critical to stage prove At metaphase II, the autosomal dyads lie either or reductional equational separa- on the periphery of a spindle as the XY tion. For these we doubt that the reasons, pseudopair and the m-chromosome orient of L. are m-chromosomes singalensis equa- in the center of the spindle (Fig. 116c). tional at the first division. More detailed 117. Aphanus sp. (PDA-33).—The sper- work must be done on the behavior of the matogonial metaphase of this Aphanus m-chromosomes in this species. species consists of five pairs of autosomes, Chromosome behavior meiosis during a pair of m-chromosomes, and an XY sex in the tribe is more or less heterogeneous. pair (Fig. 117a). All except the m-chro- in size from Most genera and species show the usual mosomes gradually decrease pattern in spermatogenesis. However, in large to small. The m-chromosomes are 774 The University of Kansas Science Bulletin Rhyparochrominae ' UDEOCORINI • c a ft A b *

lit) Serranegra sp.

RHYPAROCHROMINI

lib Anepsiodes nitidus^

a t «b m | V;* •••»• V"«

17 Aphanus sp. PDA-33

• a lb 9 ••••I • 5 I 9 • 118 Dieuches sp. - PDA- 14

119 Dieuches basiceps ™W • wftp • >

tw *• * a d ftI • c • ••••• {# i : t t • » IZU Elasmolomus transversus

first meta- Fig. 115-120. Chromosomes of named species of Rhyparochrominae: a, spermatogonial metaphase; b, 10 phase; c, second metaphase. (Exception Fig. 119: c, first anaphase; d, second metaphase.) Scale = yum. Cytotaxonomy of Lygaeidae 775 the smallest components in the set and are The course of meiosis (Fig. 120b, c) is as nitidus. readily recognized. The course of meiosis in Anepsiodes (Fig. 117b, c) is as in Anepsiodes nitidus, 121. Graphoraglius novitus (Distant).— previously described. Graphoraglius novitus has the lowest chro- Dieuches and D. 118. — sp. (PDA-14), sp. mosome number in the Lygaeidae. The (69-17). The spermatogonial metaphase spermatogonial metaphase contains three of these two Dieuches consists of species pairs of autosomes, a pair of m-chromo- a of m-chro- four pairs of autosomes, pair somes, and an XY sex pair (Fig. 121a). sex mosomes, and an XY pair (Fig. 118a). One of the three autosome pairs is very the four autosome is One of pairs very much larger than the others. The X chro- the others. The m- much larger than mosome belongs to the small-sized group chromosomes are the smallest components of autosomes and the Y is smaller than in the set and are easily distinguished the X. The m-chromosomes are the small- from the rest. The meiotic sequence (Fig. est components in the set. The course of is in nitidus. 118b, c) as Anepsiodes meiosis (Fig. 121b, c) is quite orthodox — is the same as in nitidus. 119. Dieuches sp. (prob. patruelis). and Anepsiodes has one more This species of Dieuches 122. Metochus uniguttatus (Thunberg). the other pair of autosomes than species —The chromosome cytology of Metochus of Dieuches described. There are five pairs uniguttatus had been investigated by and of autosomes, an m-chromosome pair, Manna (1951). Our observations confirm sex in the the X and Y chromosomes sper- his findings. The spermatogonial meta- Al- matogonial metaphase (Fig. 119a). phase of the species consists of four pairs of autosomes though there is a large pair of autosomes, a pair of m-chromosomes, and D. in Dieuches sp. (PDA-14) sp. and an XY sex pair (Fig. 122a). One of of autosomes is (69-17), no large pair the autosome pairs is very much larger recognized in this species. than the others. The m-chromosomes are in the set. The The course of meiosis is as in the spe- the smallest components meiotic is as in cies previously described in essential fea- process (Fig. 122b, c) tures. At the first metaphase, there are Anepsiodes nitidus. five autosomal tetrads, an m tetrad, and 123. Naudarensia manipurensis Distant. m- the X and Y dyads (Fig. 119b). The —The spermatogonial metaphase of Nau- the chromosomes are reductional and X darensia manipurensis consists of five pairs first division and Y are equational at the of autosomes, an m-chromosome pair, and is there are five (Fig. 119c). As usual, an XY sex pair (Fig. 123a). All except the and the XY autosomal dyads, m-dyad, the m-chromosomes gradually decrease in at the second (Fig. pseudopair metaphase size from large to small. The m-chromo- 119d). somes are the smallest components in the 120. Elasmolomus transversus (Signo- set. The course of meiosis (Fig. 123b, c) and E. mendicus Stal.—These two rett), is as in Anepsiodes nitidus. in species of Elasmolomus are the same 124. Peritrechus tristis Van Duzee.— their chromosome cytology. The male dip- The male diploid chromosome comple- loid chromosome complement consists of ment of Peritrechus tristis consists of five five pairs of autosomes, a pair of m-chro- of a of m-chromo- mosomes, and the X and Y sex chromo- pairs autosomes, pair somes, and an XY sex 124a). somes (Fig. 120a). One of the five auto- pair (Fig. All the m-chromosomes are similar some pairs is larger than the others, and except small- the smallest pair is the m-chromosomes. in size. The m-chromosomes, much 776 The University of Kansas Science Bulletin

Rhyparochrominae RHYPAROCHROMINI

121 Graphoraglius novitus

b * *•* a m. A

122\/J MetochusMpfnrVinc uniguttatustin icrn4- + at-iic

• %% ,23Itu Naudarensia manipurensis

.«-a • b • c * • •Sv % t m It4 Peritrechus tristis

a _ f |b f c

IZO Phorcinus albofasciatus

<« !'••• •:•• «# • • • t IZo Poeantius festivus t^P

first meta- Fig. 121-126. Chromosomes of named species of Rhyparochrominae: a, spermatogonial metaphase; b, phase; c, second metaphase. (Exception Fig. 126: d, second anaphase.) Scale = 10 /mi. Cytotaxonomy of Lygaeidae 777 cr than any other chromosomes, arc the chromosome locates in the center of a ring smallest components in the set. formed by the autosomes and the m-chro- mosome This unusual ar- The meiotic sequence (Fig. 124b) is (Fig. 126c). of the similar to that of Anepsiodes nitidus ex- rangement m-chromosome is similar to that of Peritrechus tristis. At cept that as the second metaphase is anaphase formed, the autosomes and the m-chromo- II, the X moves to one pole (Fig. 126d) as the result of the second some locate on the periphery of a spindle and, division, there are two of as the XY pseudopair lies in the center types spermatids: 5 -f- m X and 5 m. (Fig. 124c). This arrangement of the m- + + chromosome at the second metaphase is Megalonotini. unlike that in most other species in the and three Rhyparochromini. Two genera species have — been studied by Pfaler-Collander (1941; 125. Phorcimts albofasciatus (Stal). see Table 10). Essentially, the chromo- The chromosome cytology of Phorcimts some are the same, the dif- albofasciatus is the same as in Naudaren- complements ferences being due to the number of X sia manipurensis. The spermatogonia! chromosomes. We have no new data on metaphase of the species consists of five this tribe. pairs of autosomes, an m-chromosome pair, and the X and Y sex chromosomes (Fig. Gonianotini. 125a). The five pairs of autosomes and the X are similar in size. The Y is much To date, seven genera and eight species have been smaller than the X, but is more than twice investigated. This tribe contains three of chromosome as large as the m-chromosome. The course types complements: 14 16 and 18 of meiosis (Fig. 125b, c) is quite orthodox. (12 + XY), (14 + XY), 126. The modal number of chro- Poeantius jestivus Distant, P. sp. (16 + XY). mosomes for the tribe is not clear. (Thailand), and P. sp. (#128).—Chromo- yet The chromosome meiosis some cytology of these three species of cytology during is orthodox at first but at Poeantius is the same. The spermato- meiosis, second, the m-chromosome tends to locate on the gonia! metaphase consists of five pairs of instead of in the usual central autosomes, a pair of m-chromosomes, and periphery the sole X chromosome (Fig. 126a). All position. the m-chromosome are similar in 127. Delochilocoris illutninatus except — (Dis- size. The m-chromosomes are much the tant). The spermatogonial metaphase of smallest components in the set. Jande Delochilocoris illutninatus consists of six (1959a) reported the chromosome system pairs of autosomes, a pair of m-chromo- of P. jestivus. His observation is the same somes, and an XY sex pair (Fig. 127a). as our findings. One of the six autosome pairs is smaller is in size to the The course of meiosis is similar to that than the others and equal Y. The X chromosome to of Phorcimts albofasciatus. However, these may belong the medium-sized of autosomes and Poeantius species have no Y chromosome. group is not from the autosomes. At metaphase I, five autosomal tetrads distinguishable The m-chromosomes are the smallest com- take a peripheral position while the X in the set. dyad and the m-chromosome usually lie ponents in the center of the spindle (Fig. 126b). In meiosis, the X and Y chromosomes The first meiosis is reductional for the are positively heteropycnotic in the early m-chromosomes and equational for the X prophase and become isopycnotic by late chromosome. At metaphase II, the X diakinesis. They are in nonhomologous 778 The University of Kansas Science Bulletin

association at the diffuse stage and sepa- of a spindle formed by the autosomes and rate in the early diplotene stage. In the the m-chromosome (Fig. 127c). diplotene, they can be resolved as double 128. Emblethis vicarius Horvath.—The structures. The tetrad nature of the auto- spermatogonial metaphase of Emblethis somes becomes evident right after the dif- vicarius consists of five pairs of autosomes, fuse stage and they pass into a typical a pair of m-chromosomes, and an XY sex diakinesis. The m-chromosomes are un- pair (Fig. 128a). One pair of autosomes paired during the prophase. is very much larger than the others, three As metaphase I is formed, six auto- pairs are medium-sized, and one is small. somal tetrads orient on the periphery of The X is the same size as the medium- a hollow spindle, with the X and Y dyads sized autosomes, and the Y is similar in and the m-chromosomes in the center size to the small autosomes. The m-chro- (Fig. 127b). The first meiosis is equa- mosomes are the smallest components in tional for the sex chromosomes and reduc- the set. The meiotic sequence (Fig. 128b, tional for the m-chromosomes. The second c) is similar to that of Delochilocoris il- meiosis follows after the first with- luminatits in directly essential features. — out any resting stage. At metaphase II, 129. Malezonotus sodalicius (Uhler). the XY pseudopair orients in the center The male diploid chromosome comple-

^ Rhyparochrominae ft • • GONIANOTINT a j c f

127 Delochi locoris i 1 lumina tus

a • tb • : ) • * 128 Emblethis vicarius

0% a b • in i : t t I/O Malezononus sodalicius

Subfamily ? a

••V

130 Meschia sp. PDA-6

Fie. 127-130. Chromosomes of named species of Rhyparochrominae and of Meschia, incertae sedis: a, sperma- togonial metaphase; b, first metaphase; c, second metaphase. Scale = 10 fim. Cytotaxonomy of Lygaeidae 779 merit of Malezonotus sodalicius consists of species in the family, and many new gen- era have been since six pairs of autosomes, a pair of m-chro- and species proposed mosomes, and an XY sex pair (Fig. 129a). 1964. We provide cytological data for 12 All the autosomes gradually decrease in subfamilies; a total of 131 genera and 330 here. size from large to small. The m-chromo- species are discussed Unfortunately, somes are the smallest components in the no specimens were available to represent set. The course of meiosis (Fig. 129b, c) several small subfamilies nor any member is as in Delochilocoris illuminatus. of the family Idiostolidae, which is primi- tive to the Lygaeidae. Some crucial gen- Incertae Sedis era and species in the studied subfamilies remain unobserved, and the nearly total 130. Meschia sp. (PDA-6).—The sper- lack of material from Australia and South matogonial metaphase of this species of America and of material from Asia Meschia consists of six pairs of autosomes, rarity and the Pacific Islands Hawaii) a pair of m-chromosomes, and an XY sex (except all indicate that much additional work is pair (Fig. 130a). One of the six autosome others. if the Lygaeidae are to be well pairs is larger than the The Y required known chromosome is smaller than autosomes cytologically. a and is larger than the m-chromosomes. Although this study represents great The m-chromosomes are the smallest com- increase in our cytological knowledge, only have ponents in the set. about 10% of the described species been studied. the conclusions In meiosis, the X and Y chromosomes Obviously, that be reached are limited. It should are positively heteropyenotic in early pro- may also be noted that of the observed phase and become isopyenotic by late dia- analysis facts about the must kinesis. They are in nonhomologous as- cytological Lygaeidae on what is known about sociation at the diffuse stage and are depend heavily the other of Heteroptera, and few fam- separate at the diplotene stage. At groups ilies have been as well studied as are the diplotene stage they can be resolved as for a sum- double structures. The autosomes become lygaeids (see Ueshima, 1979, of the cytology of the Heteroptera). evident right after the diffuse stage and mary m- However, patterns have emerged that can pass into a typical diakinesis. The be discussed. chromosomes are unpaired during the pro- usefully While information has often phase and are negatively heteropyenotic. cytological been used as a basis for work As the first metaphase is formed, six phylogenetic on of exclusive use of autosomal bivalents lie on the periphery of groups organisms, data has sometimes resulted in un- a hollow spindle while the X and Y uni- gross data must valents and the m-chromosome orient in likely conclusions. Cytological be used in the same as more tradi- the center of the spindle (Fig. 130b). At way tional morphological data, and the same the second metaphase, the XY pseudopair stud- rules of analysis apply. Phylogenetic lies in the center of a formed by the ring be used ies require that unique characters autosomes and the m-chromosomes (Fig. to assemble nesting sets of holophyletic 130c). that contain all groups, that is, groups descendants of their most recent ancestor Systematic and Cytological Discussion (Ashlock, 1971, 1972, 1974). Unfortunate- no characters are Slater's Catalogue of the Lygaeidae of ly, cytological unique as a whole or to the World (1964) lists 20 subfamilies. He either to the family any the Characters that includes about 480 genera and nearly 2,400 group within family. 780 The University of Kansas Science Bulletin

seem to be are discussed below significant somes, and a decrease through fusion of in of these light phylogenetic principles. autosomes. It is generally agreed that an increase in number through fragmentation Chromosomes HoloJ{inetic occurs more often in organisms with holo- kinetic Heteroptera are peculiar in that their chromosomes (Schrader, 1974; chromosomes have a diffuse or holocentric Heizer, 1950; Schrader and Hughes- centromere, which results in the highly Schrader, 1956; Brown, 1961). Hughes- Schrader condensed, round configurations of these and Schrader (1961) induced of chromosomes during division (Ueshima, breakage chromosomes in some penta- tomids and 1979). The Homoptera having the found that the fragments be- have same kind of chromosomes, cytological evi- quite normally and perpetuate them- selves the meiotic dence can be added to the great body of during cycle. The possi- of morphological evidence that the Heterop- bility fusion of two chromosomes in tera with holokinetic and the Homoptera are closely re- organisms chromosomes, which lated. These chromosomes are not unique reduces the chromosome number to one, has been discussed the order Hemiptera (sensu lato), for by by Schrader similar chromosomes are found in the (1947) in the pentatomids, by Chickering and Bacorn Odonata and Lepidoptera in the insects (1933) for belostomatids, by and in Ueshima for the some sedges among the plants (\96bb) cimidids, and by (Ueshima, 1979). Brown (1961) for the coccids. The male diploid chromosome comple- Chromosome Number ments in the Lygaeidae so far known

Chromosome number alone is not a range from 10 to 30; the odd numbers 19, and 29 are useful phylogenetic indicator. All morpho- 25, 27, not represented (Table 14 logical and behavioral features of chromo- 10), and (12 + XY) and 16 (14 + somes as are common and well as the noncytological char- XY) very may be taken acters of groups must also be considered as two modal (or type) numbers in the if significant results are to be obtained. family. The number 16, however, seems often to be derived from When Southwood and Leston (1959) de- species with a chromosome 14. rived the Berytidae from Cyminae, com- number of In the Orsilli- the nae the all bining two into a single family be- (Table 10), Nysiini nearly cause of have 14 while the a shared high diploid chromosome chromosomes, Metrar- number (and two other dubious charac- gini nearly all have 16. The exception in the ters), they ignored the fact that all Cymi- metrargines is the genus Darwinysins, nae so far studied have an m-chromosome, the most primitive genus of the tribe so far while all Berytidae lack this structure. cytologically studied, which has a chro- mosome number of 14. Proposal of a Cyminae-Berytidae relation- Ashlock (unpubl.) was believes that the are derived ship unjustified, as has been carefully Metrargini from if so, the chromosome num- documented by Hamid (1975), even Nysiini; his ber of 14 is while the 16 chromo- though chromosomal data (1975:23, primitive somes found in the Table 2) are in many ways inaccurate. rest of the Metrargini is derived. The one not 14 The significance of chromosome num- Nysiini having ber chromosomes is tenellus depends in part upon the ways in Nysius Barber, which which has 22. This is chromosome numbers may change. species not primi- Two courses of evolution tive in the seem most likely genus, and the chromosome in these species: an increase in chromo- number of 22 must be derived from the some number by fragmentation of auto- 14 found in all other members of the Cytotaxonomy of Lygaeidae 781

cladistic of the involved. genus investigated. In the Orsillini, the analysis groups has such an genus Orthotonus has species with both Harrington (1976) analysis 14 and 16 chromosomes. In the Blissinae, completed for Myodochini. Slater the situation is even clearer because The highest chromosome numbers in and Ashlock (1976) have published a cla- the Lygaeidae are found in the Cymini distic analysis of the more primitive gen- (Cyminae) (28 and 30), with the (prob- of the more era of the subfamily. Three ably) more primitive Ontiscini (22) and primitive genera (Blissus, Dimorphopter- Ninini (22) not far behind. The only 15 studied us, and Geoblissus), containing ninine exception is Ninus insignis (Stal), have 14 chromo- species, all uniformly which has a chromosome number of 16. somes. Members of more advanced gen- The Geocorinae show 16 to 20 chromo- 16 era have either 14 or chromosomes, somes, with the highest numbers in the the distributed so as to suggest that change highly derived genus Geocoris. The classi- more than from 14 to 16 has occurred fication of the Geocorinae is in especially of these two subfamilies once. All species poor condition from subfamily to species have one auto- that have 14 chromosomes level, and requires much work before some that is classified as extremely large, proper evaluation of cytological data may than 14 lack this while those with more be attempted. The only members of the Thus it seems large chromosome. likely Rhyparochrominae with unusually high that the large chromosome has fragmented chromosome numbers are the Drymini of evolution of the 16-chro- in the process already mentioned (16 to 21), with the mosome species. majority of species at 20. in the In addition to Nysiits tenellus The rhyparochromine tribe Lethaeini simulus and orsillines, Lygaeus Oncopeltus contains those lygaeids with the lowest famelicus in the Lygaeinae and Pachygron- chromosome numbers (11 to 13), partly tha barberi in the Pachygronthinae have due to the lack in this group of the Y than is chromosome numbers far higher chromosome. Since the closely related These usual for their genera (Table 10). Antillocorini mostly have chromosome to have in- species would seem undergone numbers of 14 (one species is 16) it seems number creases in chromosome by frag- probable that the lower numbers in the mentation. Lethaeini are in part due to fusion. On the other hand, in the subfamily Size Rhyparochrominae, members of the tribes Chromosome and the commonly Drymini Myodochini Lygaeids have relatively large chromo- show a number of chromosomes; less large somes compared to those found in such than half of the observed showed species other heteropteran families as the Cimi- lower chromosome numbers. In Drymini, cidae. But even with these large chromo- 20 show 20 one species (18 + XY), species somes, members of four subfamilies have shows 18 and three show 16 (16 + XY) one exceptionally large autosome pair. Of Table In the (14 + XY) (see 10). Myo- these the Henestarinae and Chauliopinae 30 have 16 + dochini, species (14 XY) are known cytologically from single spe- 12 have 14 chro- and species (12 + XY) cies. In the Orsillinae and Blissinae, the mosomes. In neither case is it clear wheth- extremely large chromosome is found in er fusion to lower or (higher numbers) all but a few species with a chromosome fragmentation (lower to higher) is re- number of 14. Species with a higher Solu- lack the sponsible for the range of numbers. number (usually 16) exceptional For this we believe tion of problems like these requires a chromosome. reason, 782 The University of Kansas Science Bulletin

Orsillinae 12 34567 89 10 1 m

&,. Darwinysius marginalis I lit

Glyptonysius Q. I I hylaeus t t t

(2, Neseis hiloensis approximata - E.Maui I I f • •

Q. Neseis hiloensis approximata - W.Maui I t I t I t

Nysius abnormis I f I t

Nysius tenellus Itllllll

P\ Hudsona anceps ft I I

h. Ortholomus arphnoides III!

1 Ortholomus nevadensis ft f I

Fig. 131. Relative size differences of chromosomes in named species of Orsillinae. Cytotaxonomy of Lygaeidae 783

133 Orsillinae 134 Cyminae

£ 5- 136 Myodochini

30- 30-

132 Lygaeinae XI J a E 3 8 11 14 15 C haploid number 2 0-

135 Drymini 20- 20- 20-

10- E X> 3 XI E C 3 E C 3 10- C

xi S 3 C

7 8 11

haploid number

8 9 10 11 o-1 n 6 7 8 7 8 11 haploid number haploid number haploid number

Fie. 132-136. Distribution pattern of chromosome numbers in named subfamilies and tribes of Lygaeidae. Fig. 132. Lygaeinae. Fig. 133. Orsillinae. Fig. 134. Cyminae. Fig. 135. Drymini. Fig. 135. Myodochini.

that the change in chromosome number strong (it is based mostly on primitive from 14 to 16 in these two subfamilies took characters), his opinion was supported by place by fragmentation of the large chro- Stys (1973). That both subfamilies have mosome. One exception, Ischnodemus no- the exceptionally large chromosome may tandus (Blissinae) (Fig. 47), has a chro- support the hypothesis because the large mosome number of 18, but retains the chromosome is unknown outside of the

extra-large chromosome. The remaining Lygaeidae in the Heteroptera and is as exceptions are found in two of the four close to a synapomorphous character as species of Ortholomus studied (O. ar- we have found in this study. The one phnoides, Figs. 26, 131h; O. scolopax), species each in the Henestarinae and es- which have a chromosome number of 16 pecially the Chauliopinae with the excep- while retaining the large autosome found tional chromosome is difficult to explain in the other two species studied, both of and weakens the Orsillinae-Blissinae hy- which are 14-chromosome species. If this pothesis. The origin of the large chromo- increased chromosome number came about some may have been the fusion of two by fragmentation, it was of autosomes autosomes, and there is no reason to be- other than the exceptionally large one. lieve that this must be a unique event. Ashlock (1967) suggested that Orsil- The Sex Chromosome Mechanism linae and Blissinae are closely related. Even though evidence is not particularly The sex chromosome mechanism in the 784 The University of Kansas Science Bulletin

Lygaeidae is fairly uniform. In the 330 and Schrader (1947) suggested that a sim- species investigated, 296 haxe XX females ple fragmentation of holokinetic sex chro- and XY males, while the remaining 34 mosomes serves as the major source of the species are either XX-XO or have a com- multiple sex chromosomes in the Heterop- pound X chromosome mechanism. One tera. Hughes-Schrader and Schrader species has a compound Y. There is no (1961) experimentally proved the sugges- doubt that the XX-XY mechanism is tion by inducing fragmentation of the sex primitive in the Lygaeidae. Ueshima chromosomes with X-rays in some penta- (1979) has suggested that the XX-XO tomids. Ueshima (1966a, 1966£) reported mechanism found in Gerromorpha is support for the hypothesis in relative sex primitive in the Heteroptera, but that the chromosome size differences in closely terrestrial Heteroptera gained the Y chro- related species with single and multiple mosome early in their evolution. Thus, X mechanisms in the Triatominae (Redu- the XX-XO system found in most families viidae) and Cimicidae. Reduction in auto- of the Coreidae (except the primitive Hyo- some number does not seem to occur in cephalidae) and a few Lygaeidae is secon- lygaeids with multiple sex chromosomes darily derived. (Table 10), and the origin of the multiple sex chromosomes The XX-XO system is found in all through simple fragmen- tation of sex chromosomes be members of the tribe Pachygronthini may safely assumed for the (Pachygronthinae) (9 species in 3 genera Lygaeidae. studied) except the one species of the Multiple sex chromosomes are wide- genus Uttaris, which has the XY mechan- spread in the Heteroptera, and show little ism. Slater (1955) considered Uttaris to pattern in the Lygaeidae. In the subfam- be the most primitive genus in its tribe. ily Lygaeinae, of the 25 species (12 gen- Significantly, all four species in four gen- era) studied, only one, Arocatus suboeneus era studied in the other tribe of the Montandon, has an X1X2Y system. All Pachygronthinae, the Teracriini, have the others, including Arocatus rusticus (Stal), XY system. All 14 species in seven genera are XY. Similarly in the Blissinae, one of studied in the highly derived rhyparo- the two species of Cavdarias studied has chromine tribe Lethaeinae (see Ashlock, an X1X2Y system. All other blissines (37 1964), are XO, but all of the Antillocorini species in 10 genera) are XY. In the studied (a more primitive, closely related Oxycareninae all Old World species stud- tribe) are XY. Finally, the only other ied (4 in 10 genera) have X1X2Y, but lygaeids known with the XO system are the New World Crophius bohemani (Stal) the three species studied in the genus is XY. The possible significance of this Poeantws, members of the rhyparochro- distribution of multiple X chromosomes mine tribe Rhyparochromini. cannot be determined until more species are The origin of multiple sex chromo- investigated. somes is somewhat more problematical. Of all the species of Rhyparochrominae When these mechanisms evolve in such studied, only four have multiple X chro- insects with monocentric centromeres as mosome: Thylochromus, X1X2Y; Grapto-

Orthoptera and the Diptera, the number peltits, X1X2X3X4Y; Megalontus, X1X2Y; of autosomes usually decreases as the num- and Sphragisticus, X1X2X3Y. Only one ber of sex chromosomes increases (White, lygaeid, Rhyparochomus (Panaorus) an- 1973). But in the Heteroptera no such gustatiis (Montandon) (Rhyparochro- relationship is evident (Schrader, 1947; mini), has a multiple Y chromosome, Ueshima, 1966a, \966b). Troedsson (1944) XY1Y2. Cytotaxonomy of Lygaeidae 785

of of The examples multiple sex chromo- the subfamily Lygaeinae studied (25 somes in the Lygaeidae are too scattered species in 12 genera) and all Oxycarininae to be of any taxonomic significance, except (5 species in 3 genera) lack the m-chromo- perhaps in the Oxycareninae. some. This lack may corroborate the sug- gestion by Ashlock (1957) based upon the The m -chromosome structure of the aedaegus, that these two subfamilies are related, a suggestion that The only feature of heteropteran cytol- has been otherwise uncorroborated. How- ogy that is not found outside of the sub- ever, the m-chromosome is also missing order is the m-chromosome. Most Ly- in two species of Rhyparochrominae: Tro- gaeidae have this feature, as do members postethus holosericus (Scholtz), one of six of the Colobathristidae, Largidae, Hyo- species of Antillocorini studied in four cephalidae, Stenocephalidae, Rhopalidae, genera, and Targarema stall B.-White, the Alydidae, and the Coreidae—all families only targaremine studied. Clearly, loss of in the Pentatomorpha. (For a discussion the m-chromosome in the Lygaeinae and of the division of the Heteroptera into the Oxycareninae is not an isolated event in infraorders Enicocephalomorpha, Dipso- the family, and the chromosomal evidence coromorpha, Nepomorpha, Gerromorpha, for a relationship between the two sub- Leptopodomorpha, Cimicomorpha, and families Lygaeinae and Oxycareninae is Pentatomorpha, see Stys and Kerzhner, not very strong. 1975.) Other pentatomorphs : the Penta- tomoidea, the Pyrrhocoridae, the Aradidae, Metuphase Position of the Sex and the Berytidae, lack the m-chromosome. a n d m -ch ro m oso m es The m-chromosome, then, might be used as a synapomorphous character to group The positions that chromosomes in meiosis the families that have it into a single holo- take on the equatorial plate during is constant for phyletic group. However, as Ueshima metaphase reasonably given at the auto- (1979) has reported, most families of fully species. Generally, metaphase aquatic Hemiptera (the Nepomorpha) as somes form a ring and the sex chromo- well as the Saldidae (Leptopodomorpha) somes locate in the center of the ring. also have m-chromosomes. On the other A distinguishing feature of the m-chromo- hand, these chromosomes are absent from some, in addition to negative heteropyc- all studied Gerromorpha and Cimico- nosis and the fact that the two m-chromo- do not touch is morpha. Unfortunately, the phyletic rela- somes during metaphase, their in the center of the auto- tionships of the various infraorders are not location established, and assessment is complicated somal ring with the sex chromosomes of meiosis. by indaequate cytological information in during at least one stage the Enicocephalomorpha and Dipsocoro- Table 9 summarizes the position data morpha. It seems clear that the m- we have found in the Lygaeidae. Groups chromosome evolved fairly early in the in which the sex and m-chromosomes both evolution of the and has Heteroptera locate centrally during metaphase I and subsequently been lost several times. Thus, metaphase II are the Lygaeinae (no m), while there probably does exist a holo- the Metrargini of the Orsillinae, the Cy- phyletic group marked by the first ap- mini of the Cyminae, the Blissinae, the pearance of the m-chromosome, subse- Henestarinae, the Oxycareninae (no m), quent losses make delimitation of the the Pachygronthini of the Pachygronthi- group impossible. nae (no Y except Uttaris), the Hetero- In the family Lygaeidae, all members gastrinae, and in the Rhyparochrominae, 786 The University of Kansas Science Bulletin

the Lethaeini (except Lethaeus) (no Y), II, the m-chromosomes are peripheral with the Ozophorini, the genus Cligenes of the the autosomes, and the sex chromosomes Antillocorini, the Drymini, the Stygno- alone occupy the center of the ring. This corini, and the Rhyparochromini (except condition is found in the Nysiini and Peritrechus and Poeantius). Orsillini of the Orsillinae, the Ontiscini Nearly as commonly in the Lygaeidae, and Ninini of the Cyminae, the Geocori- the sex and m-chromosomes are central nae, the Teracriini of the Pachygronthi- during metaphase I, but during metaphase nae, the unplaced genus Meschia, and in

Table 9. Summary of the characteristics of chromosome cytology in the Lygaeidae (absence of — of central m-pair, ; presence m-pair, -\-\ position, c; peripheral position, p).

Suggested Metaphase I Metaphase II Taxon modal no. m-pair ~X Y~~ ~X Y m" Lygaeinae 14(12 + XY) Orsillinae Metrargini Nysiini Orsillini [schnorhynchinae

Caprluobia ... Kleidocerys ... Pylorgus Cyminae Cymini Ontiscini Ninini Chauliopinae Blissinae Henestarinae Geocorinae Geocorini Oxycareninae

Pachygronthinae

Pachygronthini . Uttaris Teracriini Heterogastrinae Rhyparochrominae Plinthisini Lethaeini Lethaeus Ozophorini Antillocorini

Antillocoris ... Botocudo Cligenes Targaremini Drymini Stygnocorini Cleradini Myodochini Udeocorini Rhyparochromini

Peritrechus ... Poeantis Gonianotini Incertae Sedis Meschia Cytotaxonomy of Lygaeidae 787

the Rhyparochrominae, the Plinthisini, tive sizes of chromosomes in the genus Peritrechits and Neseis shows Cleridini, Myodochini, wide variation. Interesting- Poeantis of the and size Rhyparochromini, ly, chromosomal variation among the Gonianotini. subspecies of N. hiloensis is of about the same as the various A few thoroughly unusual departures magnitude among full in this Hawaiian while sub- from these two patterns are worth noting. species genus, of N. nitida all have the In the genus Lethaeus (Lethaeini, Rhy- species same chromosomal size. No conclusions parochrominae), the X chromosome is can be drawn without peripheral at metaphase I. In genera An- hybridization experiments. tillocoris and Botocudo (Antillocorini, Several other genera have been simi- Rhyparochrominae), the species investi- larly tabulated (Tables 2-8) and show gated have the m-chromosome peripheral similar variations between species. The at metaphase I and central at metaphase rhyparochromine tribe Myodochini has II. just been reclassified (Harrington, 1976), and in this several we list The most peculiar situation is in the work, species in the subfamily Ischnorhynchinae. The chro- genus Pachybrachins (Table 8) will be transferred to new mosomal evidence is ambiguous, but may genera. corroborate a suggestion of Ashlock and and Discrimination Scudder (1966), in a revision of the isch- Species Subspecies that the norhynchine genus Neocrompus, The most significant cytological work is so genus Kleidocerys (the type genus) that can be done at the species level is to unlike other genera of the subfamily that observe the behavior of chromosomes in the is At subfamily probably polyphyletic. hybrids of closely related forms. Any dis- and metaphase I, Kleidocerys Caprhiobia ruption in the normal processes of chro- both have the X and Y chromosomes pe- mosomal division is excellent evidence that and the central. ripheral m-chromosomes reproductive isolation has been achieved. In the X is and Pylorgus, only peripheral Leonard (1966), working with five forms the Y and the m are central. At metaphase of the Bhssus leucopterus complex in the II, however, the X and Y chromosomes eastern United States, found in two of his in are central and the m is Kleidocerys crosses a metaphase heteromorphic pair, In the other two the peripheral. genera, involving the extra large autosomes, which and are all central. More data X, Y, m bridged at anaphase. Ueshima (1966b) in this group is an obvious desideratum. has done extensive similar work in the In general, the positions taken by the Cimicidae. While a breakdown in the and m-chromosomes are difficult to X, Y, meiotic process is excellent evidence that evaluate. the parents of the hybrids are reproduc- The large number of Hawaiian Orsil- tively isolated, it must be remembered linae reported upon herein is the result that the opposite is not true, and normal of an attempt (P.D.A.) to test the sub- behavior of chromosomes in hybrids is not in species concept as it applies to insular itself proof that the parents are of the populations. Two species of endemic me- same species. Reproductive isolation can trargine Orsillinae, Neseis hiloensis (Per- involve behavioral and ecological factors kins) and N. nitida (B.-White), live on as well, which may be bypassed in the the native tree Pipturus, and each has a laboratory. different on of the subspecies most major Chromosome morphology and number islands each the of (two on island Ha- can provide evidence that two similar waii). Tabulation (Table 1) of the rela- populations actually represent different 788 The University of Kansas Science Bulletin

revision of the China species. Specimens of two populations of genus Neocrompus (Hemip- Pacific Insects 8: the Cavelarius collected tera-Heteroptera: Lvgaeidae). genus (Blissinae) 686-694. feet of in within a few one another north- Banerjee, M. K. 1958. A study of the chromosome meiosis in of ern Thailand, of which one was entirely during twenty-eight species Hemip- tera Proc. Zool. Soc. while the other was (Heteroptera, Homoptera). long-winged mostly Calcutta 11:9-37. micropterous, proved to be separate species Browx, S. W. 1961. Fracture and fusion of coccid chromosomes. Nature 191:1410-1420. (Slater et al., 1969). C. illustris Distant, Chickerixg, A., and B. Bacorn. 1933. Spermato- the species with wing polymorphism, also genesis in the Belostomatidae, IV: Multiple chro- has a while the multiple X chromosome, mosomes in Lethrocenti. Pap. Mich. Acad. Sci. 17:529-533. other species, C. minor Slater and Miya- Geitler, L. 1939. Das Heterochromatin der Gesch- moto, has the normal single X chromo- lechtschromosomen bei Heteropteran. Chromo- some. In the Hawaiian Orsillinae, one of soma 1:197-229. O. 1956. Studies on the meiotic and mi- the more interesting findings is a single Halkka, totic cell division in certain Hemiptera under specimen of what was thought to be normal and experimental conditions. Ann. Acad. Neseis hiloensis approximate, which differs Sci. Fenn. 32:5-80. from all other specimens of the genus in Hamid, A. 1975. A systematic revision of the Cy- minae (Heteroptera: Lygaeidae) of the world, that it has an additional autosome pair. with a discussion of the morphology, biology, Careful of the showed that study specimen phylogeny, and zoogeography. Entomol. Soc. it differs from typical specimens of N. h. Nigeria, Occ. Publ. 14:179 p.

Harrington, B. J. 1976. Genera of of approximata in its pronotal cicatrices, Myodochini the world (Hemiptera: Lygaeidae; Rhyparo- which are brown rather than black. pale chrominae). Dissertation: Univ. of Connecticut, Later attempts to collect this exceptional Storrs. (In p-ess.) 'P. 1950. The chromosome of two form at the original site of the Kaualewe- Heizer, cytology species of the Pacific genus Oechalia (Pentatomi- lewe-Puu Kukui trail, 3,000 ft.. West dae, Hemiptera-Heteroptera), Oechalia patruelis failed, but about 100 from Maui, yards Stal, and Oechalia pacifica Stal. J. Morphol. 87: 179-226. the collection site, a large series of typical Hughes-Schrader, S., and F. Schrader. 1961. The N. h. approximata was collected on its kinetochore of the Hemiptera. Chromosoma 12: host plant, Pipturus. The exceptional 327-350. specimen probably represents a distinct Jande, S. S. 1959a. Chromosome number and sex mechanism in of Indian species living on a host plant other than twenty-seven species Heteroptera. Res. Bull. Panjam Univ. 10:215-217. Pipturus. . 1959/'. Chromosome number and sex mech- anism in nineteen species of Indian Heteroptera. Literature Cited Res. Bull. Panjam Univ. 10:415-417. Leonard, D. E. 1966. Biosystematics of the "leti- Ashlock., P. D. 1957. An investigation of the tax- coptcrus complex" of the genus Blissus (Heterop- onomic value of the phallus in the Lygaeidae tera: Lygaeidae). Connecticut Agr. Exp. Sta., (Hemiptera-Heteroptera). Ann. Entomol. Soc. Bull. 677. 47 p. Amer. 50:407-426. Malipatel, M. B. 1978. Revision of the Myodochini . 1964. Two new tribes of Rhyparochromi- (Hemiptera: Lygaeidae: Rhyparochrominae) of nae: A re-evaluation of the Lethaeini (Hemip- the Australian region. Austral. J. Zool., suppl. tera-Heteroptera: Lygaeidae). Ann. Entomol. ser., No. 56. 178 Soc. Amer. 57:414-422. p. Manna, G. K. 1951. A study of chromosomes dur- . 1967. A generic classification of the Or- ing meiosis in forty-three species of Indian sillinae of the world (Hemiptera-Heteroptera: Proc. Zool. Soc. Bengal 4:1-116. Lygaeidae). Univ. Calif. Publ. Entomol. 48:vi + Heteroptera. Menon, P. S. 1955. On the sex-chromo- 82 p. multiple some mechanism in a . 1971. Monophyly and associated terms. lygaeid, Oxycarenns hya- 11:483-486. Syst. Zool. 20:63-69. linipennis (Costa). Expericntia

. sex-chro- 1972. Monophylv again. Syst. Zool. 21: Mikolajskii, M. 1967. On the multiple 430-438. mosome mechanism in Trapczonotus arenarius

. 1974. The uses of cladistics. Ann. Rev. L. (Hemiptera, Lygaeidae). Experientia 23:270- Ecol. Syst. 5:81-99. 271. Ashlock, P. D., and G. G. E. Scudder. 1966. A Montgomery, T. H. 1901a. A study of the chro- Cytotaxonomy of Lygaeidae 789

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I. . 1901/'. Further studies of the chromosomes Stys, P., and M. Kerzhner. 1975. The rank and of the Hemiptera Heteroptera. Proc. Acad. Nat. nomenclature of higher taxa in recent Heterop- Sci. Philadelphia 53:261-271. tera. Acta Entomol. Bohemoslovaca 72:65-79. and N. Muramoto. 1964. . 1906. Chromosomes in the spermatogenesis Takenouchi, Y., A study of the Hemiptera-Heteroptera. Trans. Amer. of the chromosomes in five species of heterop-

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