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A comparative study of microspines in the alimentary canal of five families of Orthoptera (Saltatoria)
Pergamon
Inl. J. Insect Morphol. &Embryo/., Vol. 25, No. 3, pp. 249-260, 1996 Copynghf 0 1996 Pubbshed by Elsevier Science Ltd Printed in Great Bntain. All rights reserved 002&7322/96 $15.00+0.00
PII: SOO20-7322(96)00007-4
A COMPARATIVE STUDY OF MICROSPINES IN THE ALIMENTARY CANAL OF FIVE FAMILIES OF ORTHOPTERA (SALTATORIA)
Richard Department
of Entomology,
Kansas
J. Elzinga
State University,
Manhattan,
KS 66506, U.S.A
(Received 1 December 1995; accepted 11 April 1996) Abstract-Microspines in the alimentary tract in five families of grasshoppers and crickets (Orthoptera: Saltatoria) were studied to determine their structures and correlate them with patterns of distribution for potential use in taxonomy and future physiological studies. Short microspines were found in all sections of the foregut of each family, with the caeliferan Acrididae being the most unique, and the ensiferan families forming another group with similarities. Among the Ensifera, the Gryllacrididae and Gryllidae were the most distinctive, especially Stenopelmafus. The hindgut demonstrated another set of relationships, although less distinctive, with the Acrididae, Tettigoniidae, and Gryllacrididae appearing to be one grouping, whereas the Gryllidae and Gryllotalpidae formed another group with similarities. Copyright 0 1996 Published by Elsevier Science Ltd Index descriptors (in addition to those in the title): Acrididae, talpidae, Tettigoniidae, foregut, hindgut, intima, phylogeny.
Gryllacrididae,
Gryllidae,
Gryllo-
INTRODUCTION
Hindgut projections or spines were reported first from Orthoptera (mole crickets) by Kidd (1825) and these structures have been noted or studied since by Berlese (1909) in Gryllus campestris, and by Nation (1983), in 4 species of mole cricket. Anders (1939) reported these hindgut structures from true crickets. The relationship of these intimal structures to external structures was elucidated by Richards and Richards (1979). Judd (1948) studied 115 species of orthopteroids in 8 orders and described 2 major types of foregut with their enlarged teeth in Orthoptera, one characteristic of the Ensifera and the other of the Caelifera, but failed to report the presence of any microspines. Since then, microspines have been discovered in this section of the alimentary canal and were used in taxonomy by Bentos-Pereira and Lorier (1992), Hochuli et al. (1992, 1994), Hodge (1936, 1939, 1940), Malavasi et al. (198 la, 198 1b), Muralirangan and Ananthakrishnan (1974), and Uvarov (1966). Also, their absence in certain acridids was noted by both Bentos-Pereira and Lorier (1992) and Grant and Rentz (1967) as being important taxonomic evidence. Four additional references on orthopteran (sensu stricto) microspinal presence or absence have been published. Klein and Applebaum (1975) found numerous spikes projecting backwards or upwards in the ileum, colon, and interpad region of the rectum of the locust, Locust migratoria, but Hodge (1936) made no mention of their presence in the hindgut of Melanoplus differentialis. Malavasi et al. (1981a,b) found microspines in most sections of 249
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the foregut and ileum of 2 acridoid genera, Taeniopoda and Schistocera, and the cricket Gryllus, but noted their absence in the intestine of the grasshoppers and rectum of the cricket. The use of the scanning electron microscope (SEM) can greatly aid in locating and understanding these minute structures, yet relatively few studies have utilized this potential in understanding the intima of the alimentary canal. Malavasi et al. (1981a,b) and Nation (1983) published outstanding micrographs. Klein and Applebaum (1975) and BentosPereira and Lorier (1992) also included micrographs in their publications, the former on the ileum and colon of the locust and the latter on the foregut of certain acridimorphs. Hochuli (1994) included fine micrographs of foregut microspines and concluded that these structures most likely were used to regulate the passage of food through the foregut. The purposes of this study were: (1) to study microspines of the families of Orthoptera (sensu stricto) and determine if they demonstrate phylogenetic patterns within and among the common families; and (2) to determine if any deviations in structure and patterns exist between the foregut and hindgut as reported by Elzinga and Hopkins (1994) for the Blattaria.
MATERIALS AND METHODS The following orthopteran families and species were studied: Acrididae: Melanoplus differentialis (Thomas) and Romalea microptera (Palisot de Beauvois); Gryllacrididae: Ceuthophilus pallidus Thomas, Daihinia sp., and Stenopelmatus fuscus Haldeman; Gryllotalpidae: Gryllotalpa gryllotalpa L. and Neocurtilla hexadactyla (Perty); Gryllidae: Acheta domesticus (L.), Allonemobius fasciatus (De Geer), Gryllus assimilis (Fab.), Hapithus agitator Uhler, and Oecanthus nigricornis Walker; and Tettigoniidae: Anabrus simplex Haldeman, Amblycorypha oblongtfolia (De Geer), Neoconocephalus ensiger (Harris), Orchelimum vulgare Harris, and Scudderia texensis Saussure and Pictet. These 17 species were selected because they represented 13 subfamilies and would be expected to reflect a significant amount of any variation that existed. With the exception of R. microptera (obtained from Carolina Biological Supply Co.), S. fuscus (from California), and G. gryllotalpa (unknown locality), the specimens were collected in Kansas. Preservation was usually in Kahle’s solution. Only the adult stage was studied. Specimens were dissected under water in Petri dishes with the bottoms filled with beeswax. Each head was removed and sectioned sagitally, but the foregut was left in position to ensure accurate correlations between observations on specific sections of the gut. The remainder of the gut was removed and sectioned along the dorsal meson. Gut contents were removed, and the exposed intima was brushed with an artist’s paintbrush whose fibers had been cut short to obtain rigidity. Subsequently, detergent was added and the gut soaked for 30 min, then the intima was brushed again and flushed 4 or 5 times with distilled water forcibly ejected from a narrow diameter pipette. The cleansed gut was transferred to a dry Petri dish, spread open, and covered with microscope slide fragments to prevent curling. The specimens then were dehydrated using an ethyl alcohol series and left to dry within the closed dish. Once dry, each gut was cut into sections, oriented on SEM stubs, sputter-coated with goldpalladium, and finally viewed in an ETEC Autoscan electron microscope. Microspines were designated as being either unispinose when only a single projection arose from a scale-like base or multispinose when more than one projection was present. Any barbs (= tines) from the lateral edges of the projections were to be recorded as well as the presence of unique structures or modifications of the cuticular surface. Longitudinal scans from 1000 x to 4000 x were made throughout the length of both the foregut and hindgut. The number of longitudinal scans correlated with the width of the gut, varying from a minimum of 4 in the small H. agitator and Oecanthus nigricornis to over 8 in the much larger R. microptera. Scans also were made across the width to detect any variability on this plane, as was detected in cockroaches by Elzinga and Hopkins (1994). Because of much variability in terminology in the previously cited studies, the following standardization was used (slightly modified from Snodgrass, 1993): buccal cavity (initial space within stomodeum where dorsal dilator muscles extend to clypeus); pharynx (region where dilatory muscles extend to frons and tentorium); esophagus (from pharynx to thoracic enlargement into the crop); crop (thoracic expansion of esophagus to posterior narrowing and/or appearance of enlarged teeth); stomodeal valve (region posterior to enlarged teeth and/or section projecting into ventriculus); pylorus (anterior beginning of hindgut intima posterior to and including pyloric valve with its microspines); ileum (from pyloric valve to region narrowed into the ileum-colon valve with its microspines); and rectum (anterior part from colon-rectal valve to enlargement with rectal pads, median rectal sac with its rectal pads, and posterior rectum to the anus).
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RESULTS
Acrididae The overall gut division and shape were quite different from those of other families but similar within the family (Fig. 1). The gut diameter (when compared with the diameter of the body) was visibly large, and no enlarged proventriculus or teeth were present. The hindgut had a single short bend towards the dorsum in the colon. The microspines of the buccal cavity were usually unispinose, moderate to long (40-60 pm), and often were separated from one another by 10-20 pm. The microspines in the pharynx were located at similar intervals but were short (1.5-7 pm) and unispinose. The microspines within the esophagus and crop were aligned in definite rows (Fig. 2) with definite patterns; they were uni- to multispinose and 3-8 pm long. Microspines within the proventriculus were interspersed with the greatly reduced proventricular teeth, unispinose, and short (about 1 pm). Those on the stomodeal valve were of similar shape and size to those within the proventriculus. The pylorus of M. differendialis possessed short (3-6 pm) uni- and multispinose microspines (Fig. 3), but none were found in the ileum, colon, and rectum. Uni- to multispinose
Acrididae
Tettigoniidae,
Gryllacrididae
Gryllidae
Gryllotalpidae Fig. 1. Diagrammatic as in all subsequent
representation of the alimentary canals of Orthoptera. figures. A=anus, C =crop, E=esophagus, Co =colon, Ph = pharynx, Pr = proventriculis, R = rectum.
Anterior I =ileum,
is to the left P=pylorus,
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ones of 7-9 pm in length were noted in the valves and colon of R. microptera but not the rectum. Of special interest was the reticulated or dimpled texture of the intimal surface (infundibulate pores of Klein and Applebaum, 1975, for L. migratoria). Tettigoniidae The diameter of the gut was visibly narrower in these grasshoppers than in the Acrididae, and the hindgut was coiled. Greatly enlarged rows of teeth (Fig. 1) were present in the enlarged proventriculus or “gizzard”. The hindgut was poorly divided externally, except for the division between the colon and rectum. The buccal cavity, pharynx, and esophagus of Orchelium vulgare and Anabrus simplex had short microspines (2-7 pm), whereas they had longer microspines (9-14 pm) in Amblycorypha oblongifolia, N. ensiger, and S. texensis. The microspines in all species were flattened and uni- to poorly multispinose, and gave the appearance of overlapping roof shingles of a house (similar to Fig. 13). Microspines of the crop possessed an elongate point (Fig. 4) or points that appeared to be more sclerotized medially than at the edges. Those located anteriorly were often 2-10 pm longer than those located posteriorly. Their length varied from 10 to 25 pm, with those in Amblycorypha oblongifolia and N. ensiger being the longest. Microspines within the proventriculus were of 2 major types: short (l-5 pm), flattened, and scale-like ones on the surface of the enlarged proventricular teeth and elongated (over 100 pm) spines between the rows of teeth (Fig. 5) and sometimes at the edges of these grinding structures. The pyloric microspines (Fig. 6) were short (l-3 pm), mostly unispinose but sometimes multispinose, and separated (15-30 pm apart). The gut posterior to the pylorus usually lacked microspines, except for the colon-rectal valve (microspines l-8 pm in length and multispinose) and the anus (microspines 2-3 pm and uni- to multispinose). The entire hindgut had a reticulated to dimpled texture but the patterns were somewhat smaller than those in the acridids, and sparsely distributed sensory sensillae (Fig. 7), similar to those seen in some cockroaches (Elzinga and Hopkins, 1995), were located immediately anterior to the anus. Gryllacrididae The overall shape and diameter of the alimentary canal of these insects were very similar to those of the Tettigoniidae. Greatly enlarged teeth were found in the enlarged proventriculus as previously seen by Judd (1948). The hindgut resembled the Tettigoniidae in shape and diameter. The buccal cavity, pharynx, and esophagus had microspines that overlapped in a manner similar to that in Tettigoniidae, and consisted of both uni- and multispinal modifications (Fig. 8). They varied in length from 5 to 10 pm. The esophagus of Stenopelmatus fuscus
Fig. 2. Melanoplus differentialis. Uni- and multispinose microspines located in rows in the anterior crop. Bar = 30 pm. Fig. 3. Melunoplus differentialis. Multispinose microspines in pylorus. Bar = 2 pm. Fig. 4. Scudderia texensis. Unispinose microspines in the anterior part of crop. Bar = 2 pm. Fig. 5. Scudderia texensis. Elongated multispinose microspines between rows of large proventricular teeth. Bar = 2 pm. Fig. 6. Scudderia texensis. Multispinose microspines in the pylorus. Bar = 2 pm. Fig. 7. Scudderia texensis. Sensillum located just anterior to the anus. Bar = 2 pm.
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lacked microspines. The anterior region of the crop had both uni- and multispinose microspines with 1 to 8 tines, whereas the mid and posterior portions of the crop were differentiated into rows of microspines (2-25 pm long) separated by spaces lacking spines (Fig. 9) or areas with the spines greatly elongated dorsally and grading into shorter or no spines anteriorly (Fig. 10) and ventrally (Stenopelmatus fuscus). These spines also were slightly longer posteriorly (5-30 ,um) than in the anterior sections. Short (2-5 pm) overlapping microspines were oppressed closely to the enlarged proventricular teeth, and lengthened (over 60 pm) multispinose microspines (resembling setae) were located between these longitudinal rows of “gizzard” teeth. The major sections of the hindgut lacked microspines except for the valves. Unispinose microspines of 46 pm were found in the pylorus of Stenopelmatus fuscus whereas the other 2 species had both uni- and multispinose spines that varied in length from l-3 pm. Short (l-3 pm) microspines were seen in the ileumcolon valve, and those found in the colonrectal valve (Fig. 11) were 2-6 pm long; microspines were separated from one another in each valve. Unispinose microspines (2-6 pm) extended a short distance into the anterior part of the rectum. The intimal surface texture varied from reticulated in the colon of Stenopelmatus fuscus and rectum of Daihinia sp. to lacking such a texture in the other regions of the hindgut in all species. Gryllidae Externally, the foregut of these crickets was more similar to that of the Tettigoniidae than to the Acrididae by being narrowed and having an enlarged proventriculus and proventricular teeth, but the crop was more definitive (Fig. 1). The hindgut also resembled that of other Ensifera because of the weak distinctions of sections within the anterior intestine (Fig. 1). The microspines of the buccal cavity were uni- to multispinose, 2-7 pm in length, and usually separated (5-10 pm) from one another (Fig. 12). The pharyngeal microspines were much closer to one another than in the buccal cavity, and graded from unispinose protrusions in Oecanthus nigricornis and usually in H. agitator, to a mixture of uni- and multispinose spines that were associated closely with one another in Allonemobius fusciutus, to forming an overlapping “shingle” appearance with the multispinose microspines in G. assimilis and Acheta domesticus (Fig. 14). Lengths in the pharynx varied from 2-6 pm in length. The esophagus possessed microspines similar to those of the pharynx, except their bases were slightly wider (Fig. 13) and the length of those located dorsally in Acheta domesticus ranged up to 30 pm. The crop microspines were highly variable in this family. Shortened (l&12 pm) and multispinose microspines were common throughout this struc“mohawk” (spines located only ture in Allonemobius fasciatus; however, a conspicuous dorsally) appearance was seen in Acheta domesticus and G. assimilis with elongated (Fig. 14) dorsal multispinose microspines (7-10 tines and up to 60 pm in length in the anterior
Fig. 8. Ceuthophilus pallidus. Multispinose microspines Fig. 9. Ceuthophilus pallidus. Uni- and multispinose microspines Fig. 10. Stenopelmatus fuscus. Anterior beginning of multispinose crop. Bar = 30 pm. Fig. 11. Daihinia sp. Multispinose microspines found in the Fig. 12. Oecanthus nigricornis. Unispinose microspines in Fig. 13. Allonemobius fasciatus. Multispinose microspines
in the pharynx. Bar= 2 pm. in the midcrop area. Bar = 2 pm. microspines in dorsal region of the colon-rectal valve. Bar = 2 pm. the buccal cavity. Bar = 2 pm. in the esophagus. Bar = 2 nm.
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crop to 30-40 pm medially and 15-25 pm posteriorly). H. agitator crop microspines had a modified “mohawk” appearance, with only 5 to 7 tines per tooth (Fig. 15) and lateral spines present but only about one-third the length of those found dorsally. Except for Oecanthus nigricornis, the spines shortened in the mid crop (Fig. 15) and posterior to 5-30 pm and 826 pm, respectively, with the longest in the longitudinal ridges. The microspines found in the proventriculus were similar to those found in the Tettigoniidae, with those in some rows being multilayered and long (to 60 pm) and others being short (68 pm) with many tines. Those spines found in the stomodeal valve area were often unique, varying from short (l3 pm) microspines at right angles to the meson in short rows of 3-9 groupings in H. agitator and Oecanthus nigricornis to true elongated (10-60 pm) setae with sockets in Acheta domesticus (Fig. 16). Unlike the other families, those species studied within this family lacked microspines in the pylorus. Greatly enlarged protrusions (similar to the external scoli of some saturnid caterpillars) were seen in the ileum of both Acheta domesticus and G. assimilis, and elongate (2&40 pm) microspines projected from these protrusions. Microspines were absent in the ileum of the other gryllid species as well as in the colon of all species. However, short microspines, were normal in the valves, with uni- to multispinose ones found in the ileumcolon valve (3-10 pm) and colon-rectal valves (l-2 pm, except lacking in H. agitator) and several rows of short (l-2 pm) uni- to multispinose ones discovered in the anterior rectum of Acheta domesticus (Fig. 17); these were absent from this region in the other cricket species. No reticulations or pores were discerned in the hindgut. Gryllotalpidae The overall appearance of the alimentary canal of these insects closely resembled that of the Gryllidae, except that the crop was more oval in shape (Fig. 1) and a rectal diverticulum or sac was present at the anterior region of the rectum. The buccal cavity microspines were mostly unispinose, varying in length from 1 to 3 pm, and were isolated from one another. Within the pharynx, the bases of the unispinose microspines were enlarged so that they touched one another, but they were longer (15525 pm) in the posterior pharynx (Fig. 18) and esophagus and also became multispinose. The spines continued to lengthen in the dorsal part of the anterior crop (Fig. 19) until they reached 35 pm, but then they shortened gradually to 7-10 pm in N. hexadactyla and 24 pm in G. gryllotalpa in the posterior crop. The lateral and ventral surfaces of the crop also had microspines reduced, both in number and length, in G. gryllotalpa, but they were normally present throughout the ventral and lateral regions of the crop in N. hexadactyla. Microspines were not discernable on the surfaces of the large proventricular teeth, but they were present as elongate multispinose structures between the large proventricular teeth and extended out into much of the stomodeal valve.
Fig. 14. Gr$ius assimilis. Multispinose microspines in the mid crop area. Bar= 30 pm. Fig. 15. Hapithus agifator. Multispinose microspines in the mid crop area. Bar = 2 pm. Fig. 16. Acheta domesticus. Socketed microspines (=setae) located in the stomodeal valve area. Bar = 2 pm. Fig. 17. Acheta domesticus. Longitudinal row of multispinose microspines in the mid section of the rectum. Bar = 2 pm. Fig. 18. Gryllotalpa grvllotalpa. Uni- and multispinose microspines overlapping in the pharynx. Bar=2 pm. Fig. 19. Gryllotalpa gryllotalpa. Multispinose microspines in the anterior part of crop. Bar = 2 pm.
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Fig. 20. Gryllofdpa gryllotalpa. Enlarged scolus-like protuberance m Ileum with elongated proJectmg microspines. Bar = 30 pm. Fig. 21. Gryllotalpa grylloralpa. Uni- and multispinose microspines located in the colon-rectal valve. Bar = 2 ym.
The pylorus contained short (5-7 pm) multispinose microspines. As in some Gryllidae, large scolus-like protrusions (140-350 pm) were seen in the anterior part of the ileum (Fig. 20) each with long (40-70 pm) multispinose microspines, but none were seen in the remainder of this region. The colon, rectum, and rectal diverticulum lacked microspines; however, short (l-3 pm) multispinose microspines were observed in the ileum
DISCUSSION
The overall shape of the foregut and the modifications of the proventriculus were of 2 major types, as reported by Judd (1948). The hindgut also reflected these relationships as the Caelifera studied (Acrididae) had minimal coiling, whereas that of the Ensifera (other families studied) was more elongate and often highly coiled. The gryllacridids and tettigoniids appeared to be the most similar, followed by the gryllids and gryllotalpids, whereas the acridids were the least similar. The microspines of the foregut demonstrated similar phylogenetic relationships. In the pharynx, the Acrididae possessed isolated unispinose microspines as seen by Malavasi et al. (I981 b) and Hodge (1939), whereas the other families possessed many multispinose microspines that were usually flattened and overlapping (Hapithus and Oecanthus were exceptions). The uniqueness of Acrididae continued into the crop where the microspines were widely separated and arranged into distinctive diagonal rows with differences between species as reported by Bentos-Pereira and Lorier (1992) Hodge (1936, 1939), Judd (1948), Malavasi et al. (198 la,b), Muralirangan and Ananthakrishnan (1974) and Uvarov (1966). Such patterns were lacking in the other families, although rows may appear to be present when overlapping occurs or where rows are present but not adjacent to one another and
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not diagonally oriented (Fig. 9). Among the Ensifera, the microspines of the foregut were the most unique among the gryllacridids and some gryllids where they became elongate or were normal-sized but shortened laterally and often lost ventrally, giving the appearance of a “mohawk haircut” pattern, particularly in Stenopelmatus (Fig. 10). The proventricular spines and patterns of distribution reflected the distinction between the Caelifera and Ensifera; those of the Acrididae were short and unispinose, whereas the remaining species had short scale-like microspines on the enlarged proventricular teeth and greatly elongate ones between the rows of “gizzard” teeth that often extended out onto the surface of the stomodeal valve. In A&eta and Gryllus, these elongate structures also became socketed. The hindgut microspines exhibited differences between families. At one extreme was the grouping of Acrididae, Tettigoniidae, and Gryllacrididae that possessed microspines only in the valve regions, whereas a second grouping of Gryllidae and Gryllotalpidae sometimes possessed long microspine projections from “scoli-like” papillae in the ileum, as previously reported by Anders (1939) Berlese (1909) and Nation (1983). The similarities among the gryllids and gryllotalpids agree with the correlations noted from the foregut, but the second grouping of the remaining families is quite different. This lack of correlation probably reflects unknown physiological differences of similar but of less magnitude than those seen by Elzinga and Hopkins (1995) in Blattaria where the foregut indicated phylogenetic relationships but the hindgut did not. Acknowlrdyements-Appreciation is extended to John Krchma (Kansas State University) for his invaluable SEM assistance. This publication is Contribution No. 96-2135 of the Kansas Agricultural Experiment Station, Kansas State University. Support came from Hatch Project H033.
REFERENCES Anders,
K. 1939. Vergleichend anatomische und phylogenetische Studien tiber die Ensifera (Saltitoria). Opus. Entomol. (Suppl.) 2: l-306. Bentos-Pereira, A. and E. Lorier. 1992. Cuticular structures of the stomodeum, in Paulinia acuminata (De Geer) and Marellia remipes Uvarov (Orthoptera: Pauliniidae). Int. J. Insect Morphol. Embrvol. 21: 161-74. Berlese, A. 1909. Gli Insetti. Societa Editrice Libraria, Milano. Elzinga, R. J. and T. L. Hopkins. 1994. Foregut microspines in four families of cockroaches (Blattaria). Int. J. Insect Morphol. Embryol. 23: 253-60. Elzinga. R. J. and T. L. Hopkins. 1995. Microspine variation in hindgut regions of four families of cockroaches (Blattaria). Int. J. Insect Morphol. EmbrJol. 24: 203-l 1. Grant, H. J. and D. C. Rentn. 1967. A biosystematic review of the family Taenaoceridae including a comparative study of the proventriculus. Pan-Pacific Entomol. 43: 65-74. Hochuli, D. F. 1994. Foregut morphology of Locusta migratoria (Orthoptera: Acrididae). J. Aust. Entomol. Sot. 33: 65-9. Hochuli, D. F., B. Roberts and G. D. Sanson. 1992. Anteriorly directed microspines in the foregut of Locusra migratoria (Orthoptera: Acrididae). Int. J. Insect Morphol. Emhryol. 21: 95-l. Hodge, C. 1936. The anatomy and histology of the alimentary tract of the grasshopper Melanoplus d@rentialis Thomas. J. Morphol. 59: 423-39. Hodge, C. 1939. The anatomy and histology of the alimentary tract of Locusta migraroria L. (Orthoptera: Acrididae). J. Morphol. 64: 375-99. Hodge, C. 1940. The anatomy and histology of the alimentary tract of Radenorafum carinatum var. peninsulure Rehn and Hebard (Orthoptera: Acrididae). J. Morphol. 66: 581-603. Judd, W. W. 1948. A comparative study of the proventriculus of orthopteroid insects with reference to its use in taxonomy. Can. J. Res. 26: 933161. Kidd, J. 1825. On the anatomy of the mole cricket. Philos. Truns. R. Sot. Lond. 115: 20546. Klein, M. and S. W. Applebaum. 1975. The surface morphology of locust hindgut cuticle. J. Entomol. (A) 50: 31-6. Malavasi, J., F. Urefia and Y. Kozuka. 1981a. Microscopica electronica de barridao epitelho digestivo de1 grill0 (Gryllus sp.). Ret?. Biol. Trop. 29: 59-75.
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J., F. Ureiia and Y. Kozuka. 1981b. Estudio ultrastructural de1 epitelio digestive de Taeniopoda y Schistocerca (Saltatoria). Rev. Biol. Trap. 29: 209-26. Muralirangan, M. C. and T. N. Ananthakrishnan. 1974. Taxonomic significance of the foregut armature in some Indian Acridoidea (Orthoptera). Orient. Insect 8: 11945. Nation, J. L. 1983. Specialization in the alimentary canal of some mole crickets (Orthoptera: Gryllotalpidae). Int. J. Morphol. Embryol. 12: 201-10. Richards, A. G. and P. A. Richards. 1979. The cuticular protuberances of insects. Int. J. Morphol. Embryol. 8: 143-57. Snodgrass, R. C. 1993. Principles of Insect Morphology. Cornell University Press, Ithaca, NY. Uvarov, B. 1966. Grasshoppers and Locusts. Cambridge University Press, Cambridge, UK. Malavasi,
Inl. J. Insect Morphol. &Embryo/., Vol. 25, No. 3, pp. 249-260, 1996 Copynghf 0 1996 Pubbshed by Elsevier Science Ltd Printed in Great Bntain. All rights reserved 002&7322/96 $15.00+0.00
PII: SOO20-7322(96)00007-4
A COMPARATIVE STUDY OF MICROSPINES IN THE ALIMENTARY CANAL OF FIVE FAMILIES OF ORTHOPTERA (SALTATORIA)
Richard Department
of Entomology,
Kansas
J. Elzinga
State University,
Manhattan,
KS 66506, U.S.A
(Received 1 December 1995; accepted 11 April 1996) Abstract-Microspines in the alimentary tract in five families of grasshoppers and crickets (Orthoptera: Saltatoria) were studied to determine their structures and correlate them with patterns of distribution for potential use in taxonomy and future physiological studies. Short microspines were found in all sections of the foregut of each family, with the caeliferan Acrididae being the most unique, and the ensiferan families forming another group with similarities. Among the Ensifera, the Gryllacrididae and Gryllidae were the most distinctive, especially Stenopelmafus. The hindgut demonstrated another set of relationships, although less distinctive, with the Acrididae, Tettigoniidae, and Gryllacrididae appearing to be one grouping, whereas the Gryllidae and Gryllotalpidae formed another group with similarities. Copyright 0 1996 Published by Elsevier Science Ltd Index descriptors (in addition to those in the title): Acrididae, talpidae, Tettigoniidae, foregut, hindgut, intima, phylogeny.
Gryllacrididae,
Gryllidae,
Gryllo-
INTRODUCTION
Hindgut projections or spines were reported first from Orthoptera (mole crickets) by Kidd (1825) and these structures have been noted or studied since by Berlese (1909) in Gryllus campestris, and by Nation (1983), in 4 species of mole cricket. Anders (1939) reported these hindgut structures from true crickets. The relationship of these intimal structures to external structures was elucidated by Richards and Richards (1979). Judd (1948) studied 115 species of orthopteroids in 8 orders and described 2 major types of foregut with their enlarged teeth in Orthoptera, one characteristic of the Ensifera and the other of the Caelifera, but failed to report the presence of any microspines. Since then, microspines have been discovered in this section of the alimentary canal and were used in taxonomy by Bentos-Pereira and Lorier (1992), Hochuli et al. (1992, 1994), Hodge (1936, 1939, 1940), Malavasi et al. (198 la, 198 1b), Muralirangan and Ananthakrishnan (1974), and Uvarov (1966). Also, their absence in certain acridids was noted by both Bentos-Pereira and Lorier (1992) and Grant and Rentz (1967) as being important taxonomic evidence. Four additional references on orthopteran (sensu stricto) microspinal presence or absence have been published. Klein and Applebaum (1975) found numerous spikes projecting backwards or upwards in the ileum, colon, and interpad region of the rectum of the locust, Locust migratoria, but Hodge (1936) made no mention of their presence in the hindgut of Melanoplus differentialis. Malavasi et al. (1981a,b) found microspines in most sections of 249
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the foregut and ileum of 2 acridoid genera, Taeniopoda and Schistocera, and the cricket Gryllus, but noted their absence in the intestine of the grasshoppers and rectum of the cricket. The use of the scanning electron microscope (SEM) can greatly aid in locating and understanding these minute structures, yet relatively few studies have utilized this potential in understanding the intima of the alimentary canal. Malavasi et al. (1981a,b) and Nation (1983) published outstanding micrographs. Klein and Applebaum (1975) and BentosPereira and Lorier (1992) also included micrographs in their publications, the former on the ileum and colon of the locust and the latter on the foregut of certain acridimorphs. Hochuli (1994) included fine micrographs of foregut microspines and concluded that these structures most likely were used to regulate the passage of food through the foregut. The purposes of this study were: (1) to study microspines of the families of Orthoptera (sensu stricto) and determine if they demonstrate phylogenetic patterns within and among the common families; and (2) to determine if any deviations in structure and patterns exist between the foregut and hindgut as reported by Elzinga and Hopkins (1994) for the Blattaria.
MATERIALS AND METHODS The following orthopteran families and species were studied: Acrididae: Melanoplus differentialis (Thomas) and Romalea microptera (Palisot de Beauvois); Gryllacrididae: Ceuthophilus pallidus Thomas, Daihinia sp., and Stenopelmatus fuscus Haldeman; Gryllotalpidae: Gryllotalpa gryllotalpa L. and Neocurtilla hexadactyla (Perty); Gryllidae: Acheta domesticus (L.), Allonemobius fasciatus (De Geer), Gryllus assimilis (Fab.), Hapithus agitator Uhler, and Oecanthus nigricornis Walker; and Tettigoniidae: Anabrus simplex Haldeman, Amblycorypha oblongtfolia (De Geer), Neoconocephalus ensiger (Harris), Orchelimum vulgare Harris, and Scudderia texensis Saussure and Pictet. These 17 species were selected because they represented 13 subfamilies and would be expected to reflect a significant amount of any variation that existed. With the exception of R. microptera (obtained from Carolina Biological Supply Co.), S. fuscus (from California), and G. gryllotalpa (unknown locality), the specimens were collected in Kansas. Preservation was usually in Kahle’s solution. Only the adult stage was studied. Specimens were dissected under water in Petri dishes with the bottoms filled with beeswax. Each head was removed and sectioned sagitally, but the foregut was left in position to ensure accurate correlations between observations on specific sections of the gut. The remainder of the gut was removed and sectioned along the dorsal meson. Gut contents were removed, and the exposed intima was brushed with an artist’s paintbrush whose fibers had been cut short to obtain rigidity. Subsequently, detergent was added and the gut soaked for 30 min, then the intima was brushed again and flushed 4 or 5 times with distilled water forcibly ejected from a narrow diameter pipette. The cleansed gut was transferred to a dry Petri dish, spread open, and covered with microscope slide fragments to prevent curling. The specimens then were dehydrated using an ethyl alcohol series and left to dry within the closed dish. Once dry, each gut was cut into sections, oriented on SEM stubs, sputter-coated with goldpalladium, and finally viewed in an ETEC Autoscan electron microscope. Microspines were designated as being either unispinose when only a single projection arose from a scale-like base or multispinose when more than one projection was present. Any barbs (= tines) from the lateral edges of the projections were to be recorded as well as the presence of unique structures or modifications of the cuticular surface. Longitudinal scans from 1000 x to 4000 x were made throughout the length of both the foregut and hindgut. The number of longitudinal scans correlated with the width of the gut, varying from a minimum of 4 in the small H. agitator and Oecanthus nigricornis to over 8 in the much larger R. microptera. Scans also were made across the width to detect any variability on this plane, as was detected in cockroaches by Elzinga and Hopkins (1994). Because of much variability in terminology in the previously cited studies, the following standardization was used (slightly modified from Snodgrass, 1993): buccal cavity (initial space within stomodeum where dorsal dilator muscles extend to clypeus); pharynx (region where dilatory muscles extend to frons and tentorium); esophagus (from pharynx to thoracic enlargement into the crop); crop (thoracic expansion of esophagus to posterior narrowing and/or appearance of enlarged teeth); stomodeal valve (region posterior to enlarged teeth and/or section projecting into ventriculus); pylorus (anterior beginning of hindgut intima posterior to and including pyloric valve with its microspines); ileum (from pyloric valve to region narrowed into the ileum-colon valve with its microspines); and rectum (anterior part from colon-rectal valve to enlargement with rectal pads, median rectal sac with its rectal pads, and posterior rectum to the anus).
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RESULTS
Acrididae The overall gut division and shape were quite different from those of other families but similar within the family (Fig. 1). The gut diameter (when compared with the diameter of the body) was visibly large, and no enlarged proventriculus or teeth were present. The hindgut had a single short bend towards the dorsum in the colon. The microspines of the buccal cavity were usually unispinose, moderate to long (40-60 pm), and often were separated from one another by 10-20 pm. The microspines in the pharynx were located at similar intervals but were short (1.5-7 pm) and unispinose. The microspines within the esophagus and crop were aligned in definite rows (Fig. 2) with definite patterns; they were uni- to multispinose and 3-8 pm long. Microspines within the proventriculus were interspersed with the greatly reduced proventricular teeth, unispinose, and short (about 1 pm). Those on the stomodeal valve were of similar shape and size to those within the proventriculus. The pylorus of M. differendialis possessed short (3-6 pm) uni- and multispinose microspines (Fig. 3), but none were found in the ileum, colon, and rectum. Uni- to multispinose
Acrididae
Tettigoniidae,
Gryllacrididae
Gryllidae
Gryllotalpidae Fig. 1. Diagrammatic as in all subsequent
representation of the alimentary canals of Orthoptera. figures. A=anus, C =crop, E=esophagus, Co =colon, Ph = pharynx, Pr = proventriculis, R = rectum.
Anterior I =ileum,
is to the left P=pylorus,
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ones of 7-9 pm in length were noted in the valves and colon of R. microptera but not the rectum. Of special interest was the reticulated or dimpled texture of the intimal surface (infundibulate pores of Klein and Applebaum, 1975, for L. migratoria). Tettigoniidae The diameter of the gut was visibly narrower in these grasshoppers than in the Acrididae, and the hindgut was coiled. Greatly enlarged rows of teeth (Fig. 1) were present in the enlarged proventriculus or “gizzard”. The hindgut was poorly divided externally, except for the division between the colon and rectum. The buccal cavity, pharynx, and esophagus of Orchelium vulgare and Anabrus simplex had short microspines (2-7 pm), whereas they had longer microspines (9-14 pm) in Amblycorypha oblongifolia, N. ensiger, and S. texensis. The microspines in all species were flattened and uni- to poorly multispinose, and gave the appearance of overlapping roof shingles of a house (similar to Fig. 13). Microspines of the crop possessed an elongate point (Fig. 4) or points that appeared to be more sclerotized medially than at the edges. Those located anteriorly were often 2-10 pm longer than those located posteriorly. Their length varied from 10 to 25 pm, with those in Amblycorypha oblongifolia and N. ensiger being the longest. Microspines within the proventriculus were of 2 major types: short (l-5 pm), flattened, and scale-like ones on the surface of the enlarged proventricular teeth and elongated (over 100 pm) spines between the rows of teeth (Fig. 5) and sometimes at the edges of these grinding structures. The pyloric microspines (Fig. 6) were short (l-3 pm), mostly unispinose but sometimes multispinose, and separated (15-30 pm apart). The gut posterior to the pylorus usually lacked microspines, except for the colon-rectal valve (microspines l-8 pm in length and multispinose) and the anus (microspines 2-3 pm and uni- to multispinose). The entire hindgut had a reticulated to dimpled texture but the patterns were somewhat smaller than those in the acridids, and sparsely distributed sensory sensillae (Fig. 7), similar to those seen in some cockroaches (Elzinga and Hopkins, 1995), were located immediately anterior to the anus. Gryllacrididae The overall shape and diameter of the alimentary canal of these insects were very similar to those of the Tettigoniidae. Greatly enlarged teeth were found in the enlarged proventriculus as previously seen by Judd (1948). The hindgut resembled the Tettigoniidae in shape and diameter. The buccal cavity, pharynx, and esophagus had microspines that overlapped in a manner similar to that in Tettigoniidae, and consisted of both uni- and multispinal modifications (Fig. 8). They varied in length from 5 to 10 pm. The esophagus of Stenopelmatus fuscus
Fig. 2. Melanoplus differentialis. Uni- and multispinose microspines located in rows in the anterior crop. Bar = 30 pm. Fig. 3. Melunoplus differentialis. Multispinose microspines in pylorus. Bar = 2 pm. Fig. 4. Scudderia texensis. Unispinose microspines in the anterior part of crop. Bar = 2 pm. Fig. 5. Scudderia texensis. Elongated multispinose microspines between rows of large proventricular teeth. Bar = 2 pm. Fig. 6. Scudderia texensis. Multispinose microspines in the pylorus. Bar = 2 pm. Fig. 7. Scudderia texensis. Sensillum located just anterior to the anus. Bar = 2 pm.
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lacked microspines. The anterior region of the crop had both uni- and multispinose microspines with 1 to 8 tines, whereas the mid and posterior portions of the crop were differentiated into rows of microspines (2-25 pm long) separated by spaces lacking spines (Fig. 9) or areas with the spines greatly elongated dorsally and grading into shorter or no spines anteriorly (Fig. 10) and ventrally (Stenopelmatus fuscus). These spines also were slightly longer posteriorly (5-30 ,um) than in the anterior sections. Short (2-5 pm) overlapping microspines were oppressed closely to the enlarged proventricular teeth, and lengthened (over 60 pm) multispinose microspines (resembling setae) were located between these longitudinal rows of “gizzard” teeth. The major sections of the hindgut lacked microspines except for the valves. Unispinose microspines of 46 pm were found in the pylorus of Stenopelmatus fuscus whereas the other 2 species had both uni- and multispinose spines that varied in length from l-3 pm. Short (l-3 pm) microspines were seen in the ileumcolon valve, and those found in the colonrectal valve (Fig. 11) were 2-6 pm long; microspines were separated from one another in each valve. Unispinose microspines (2-6 pm) extended a short distance into the anterior part of the rectum. The intimal surface texture varied from reticulated in the colon of Stenopelmatus fuscus and rectum of Daihinia sp. to lacking such a texture in the other regions of the hindgut in all species. Gryllidae Externally, the foregut of these crickets was more similar to that of the Tettigoniidae than to the Acrididae by being narrowed and having an enlarged proventriculus and proventricular teeth, but the crop was more definitive (Fig. 1). The hindgut also resembled that of other Ensifera because of the weak distinctions of sections within the anterior intestine (Fig. 1). The microspines of the buccal cavity were uni- to multispinose, 2-7 pm in length, and usually separated (5-10 pm) from one another (Fig. 12). The pharyngeal microspines were much closer to one another than in the buccal cavity, and graded from unispinose protrusions in Oecanthus nigricornis and usually in H. agitator, to a mixture of uni- and multispinose spines that were associated closely with one another in Allonemobius fusciutus, to forming an overlapping “shingle” appearance with the multispinose microspines in G. assimilis and Acheta domesticus (Fig. 14). Lengths in the pharynx varied from 2-6 pm in length. The esophagus possessed microspines similar to those of the pharynx, except their bases were slightly wider (Fig. 13) and the length of those located dorsally in Acheta domesticus ranged up to 30 pm. The crop microspines were highly variable in this family. Shortened (l&12 pm) and multispinose microspines were common throughout this struc“mohawk” (spines located only ture in Allonemobius fasciatus; however, a conspicuous dorsally) appearance was seen in Acheta domesticus and G. assimilis with elongated (Fig. 14) dorsal multispinose microspines (7-10 tines and up to 60 pm in length in the anterior
Fig. 8. Ceuthophilus pallidus. Multispinose microspines Fig. 9. Ceuthophilus pallidus. Uni- and multispinose microspines Fig. 10. Stenopelmatus fuscus. Anterior beginning of multispinose crop. Bar = 30 pm. Fig. 11. Daihinia sp. Multispinose microspines found in the Fig. 12. Oecanthus nigricornis. Unispinose microspines in Fig. 13. Allonemobius fasciatus. Multispinose microspines
in the pharynx. Bar= 2 pm. in the midcrop area. Bar = 2 pm. microspines in dorsal region of the colon-rectal valve. Bar = 2 pm. the buccal cavity. Bar = 2 pm. in the esophagus. Bar = 2 nm.
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crop to 30-40 pm medially and 15-25 pm posteriorly). H. agitator crop microspines had a modified “mohawk” appearance, with only 5 to 7 tines per tooth (Fig. 15) and lateral spines present but only about one-third the length of those found dorsally. Except for Oecanthus nigricornis, the spines shortened in the mid crop (Fig. 15) and posterior to 5-30 pm and 826 pm, respectively, with the longest in the longitudinal ridges. The microspines found in the proventriculus were similar to those found in the Tettigoniidae, with those in some rows being multilayered and long (to 60 pm) and others being short (68 pm) with many tines. Those spines found in the stomodeal valve area were often unique, varying from short (l3 pm) microspines at right angles to the meson in short rows of 3-9 groupings in H. agitator and Oecanthus nigricornis to true elongated (10-60 pm) setae with sockets in Acheta domesticus (Fig. 16). Unlike the other families, those species studied within this family lacked microspines in the pylorus. Greatly enlarged protrusions (similar to the external scoli of some saturnid caterpillars) were seen in the ileum of both Acheta domesticus and G. assimilis, and elongate (2&40 pm) microspines projected from these protrusions. Microspines were absent in the ileum of the other gryllid species as well as in the colon of all species. However, short microspines, were normal in the valves, with uni- to multispinose ones found in the ileumcolon valve (3-10 pm) and colon-rectal valves (l-2 pm, except lacking in H. agitator) and several rows of short (l-2 pm) uni- to multispinose ones discovered in the anterior rectum of Acheta domesticus (Fig. 17); these were absent from this region in the other cricket species. No reticulations or pores were discerned in the hindgut. Gryllotalpidae The overall appearance of the alimentary canal of these insects closely resembled that of the Gryllidae, except that the crop was more oval in shape (Fig. 1) and a rectal diverticulum or sac was present at the anterior region of the rectum. The buccal cavity microspines were mostly unispinose, varying in length from 1 to 3 pm, and were isolated from one another. Within the pharynx, the bases of the unispinose microspines were enlarged so that they touched one another, but they were longer (15525 pm) in the posterior pharynx (Fig. 18) and esophagus and also became multispinose. The spines continued to lengthen in the dorsal part of the anterior crop (Fig. 19) until they reached 35 pm, but then they shortened gradually to 7-10 pm in N. hexadactyla and 24 pm in G. gryllotalpa in the posterior crop. The lateral and ventral surfaces of the crop also had microspines reduced, both in number and length, in G. gryllotalpa, but they were normally present throughout the ventral and lateral regions of the crop in N. hexadactyla. Microspines were not discernable on the surfaces of the large proventricular teeth, but they were present as elongate multispinose structures between the large proventricular teeth and extended out into much of the stomodeal valve.
Fig. 14. Gr$ius assimilis. Multispinose microspines in the mid crop area. Bar= 30 pm. Fig. 15. Hapithus agifator. Multispinose microspines in the mid crop area. Bar = 2 pm. Fig. 16. Acheta domesticus. Socketed microspines (=setae) located in the stomodeal valve area. Bar = 2 pm. Fig. 17. Acheta domesticus. Longitudinal row of multispinose microspines in the mid section of the rectum. Bar = 2 pm. Fig. 18. Gryllotalpa grvllotalpa. Uni- and multispinose microspines overlapping in the pharynx. Bar=2 pm. Fig. 19. Gryllotalpa gryllotalpa. Multispinose microspines in the anterior part of crop. Bar = 2 pm.
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Fig. 20. Gryllofdpa gryllotalpa. Enlarged scolus-like protuberance m Ileum with elongated proJectmg microspines. Bar = 30 pm. Fig. 21. Gryllotalpa grylloralpa. Uni- and multispinose microspines located in the colon-rectal valve. Bar = 2 ym.
The pylorus contained short (5-7 pm) multispinose microspines. As in some Gryllidae, large scolus-like protrusions (140-350 pm) were seen in the anterior part of the ileum (Fig. 20) each with long (40-70 pm) multispinose microspines, but none were seen in the remainder of this region. The colon, rectum, and rectal diverticulum lacked microspines; however, short (l-3 pm) multispinose microspines were observed in the ileum
DISCUSSION
The overall shape of the foregut and the modifications of the proventriculus were of 2 major types, as reported by Judd (1948). The hindgut also reflected these relationships as the Caelifera studied (Acrididae) had minimal coiling, whereas that of the Ensifera (other families studied) was more elongate and often highly coiled. The gryllacridids and tettigoniids appeared to be the most similar, followed by the gryllids and gryllotalpids, whereas the acridids were the least similar. The microspines of the foregut demonstrated similar phylogenetic relationships. In the pharynx, the Acrididae possessed isolated unispinose microspines as seen by Malavasi et al. (I981 b) and Hodge (1939), whereas the other families possessed many multispinose microspines that were usually flattened and overlapping (Hapithus and Oecanthus were exceptions). The uniqueness of Acrididae continued into the crop where the microspines were widely separated and arranged into distinctive diagonal rows with differences between species as reported by Bentos-Pereira and Lorier (1992) Hodge (1936, 1939), Judd (1948), Malavasi et al. (198 la,b), Muralirangan and Ananthakrishnan (1974) and Uvarov (1966). Such patterns were lacking in the other families, although rows may appear to be present when overlapping occurs or where rows are present but not adjacent to one another and
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not diagonally oriented (Fig. 9). Among the Ensifera, the microspines of the foregut were the most unique among the gryllacridids and some gryllids where they became elongate or were normal-sized but shortened laterally and often lost ventrally, giving the appearance of a “mohawk haircut” pattern, particularly in Stenopelmatus (Fig. 10). The proventricular spines and patterns of distribution reflected the distinction between the Caelifera and Ensifera; those of the Acrididae were short and unispinose, whereas the remaining species had short scale-like microspines on the enlarged proventricular teeth and greatly elongate ones between the rows of “gizzard” teeth that often extended out onto the surface of the stomodeal valve. In A&eta and Gryllus, these elongate structures also became socketed. The hindgut microspines exhibited differences between families. At one extreme was the grouping of Acrididae, Tettigoniidae, and Gryllacrididae that possessed microspines only in the valve regions, whereas a second grouping of Gryllidae and Gryllotalpidae sometimes possessed long microspine projections from “scoli-like” papillae in the ileum, as previously reported by Anders (1939) Berlese (1909) and Nation (1983). The similarities among the gryllids and gryllotalpids agree with the correlations noted from the foregut, but the second grouping of the remaining families is quite different. This lack of correlation probably reflects unknown physiological differences of similar but of less magnitude than those seen by Elzinga and Hopkins (1995) in Blattaria where the foregut indicated phylogenetic relationships but the hindgut did not. Acknowlrdyements-Appreciation is extended to John Krchma (Kansas State University) for his invaluable SEM assistance. This publication is Contribution No. 96-2135 of the Kansas Agricultural Experiment Station, Kansas State University. Support came from Hatch Project H033.
REFERENCES Anders,
K. 1939. Vergleichend anatomische und phylogenetische Studien tiber die Ensifera (Saltitoria). Opus. Entomol. (Suppl.) 2: l-306. Bentos-Pereira, A. and E. Lorier. 1992. Cuticular structures of the stomodeum, in Paulinia acuminata (De Geer) and Marellia remipes Uvarov (Orthoptera: Pauliniidae). Int. J. Insect Morphol. Embrvol. 21: 161-74. Berlese, A. 1909. Gli Insetti. Societa Editrice Libraria, Milano. Elzinga, R. J. and T. L. Hopkins. 1994. Foregut microspines in four families of cockroaches (Blattaria). Int. J. Insect Morphol. Embryol. 23: 253-60. Elzinga. R. J. and T. L. Hopkins. 1995. Microspine variation in hindgut regions of four families of cockroaches (Blattaria). Int. J. Insect Morphol. EmbrJol. 24: 203-l 1. Grant, H. J. and D. C. Rentn. 1967. A biosystematic review of the family Taenaoceridae including a comparative study of the proventriculus. Pan-Pacific Entomol. 43: 65-74. Hochuli, D. F. 1994. Foregut morphology of Locusta migratoria (Orthoptera: Acrididae). J. Aust. Entomol. Sot. 33: 65-9. Hochuli, D. F., B. Roberts and G. D. Sanson. 1992. Anteriorly directed microspines in the foregut of Locusra migratoria (Orthoptera: Acrididae). Int. J. Insect Morphol. Emhryol. 21: 95-l. Hodge, C. 1936. The anatomy and histology of the alimentary tract of the grasshopper Melanoplus d@rentialis Thomas. J. Morphol. 59: 423-39. Hodge, C. 1939. The anatomy and histology of the alimentary tract of Locusta migraroria L. (Orthoptera: Acrididae). J. Morphol. 64: 375-99. Hodge, C. 1940. The anatomy and histology of the alimentary tract of Radenorafum carinatum var. peninsulure Rehn and Hebard (Orthoptera: Acrididae). J. Morphol. 66: 581-603. Judd, W. W. 1948. A comparative study of the proventriculus of orthopteroid insects with reference to its use in taxonomy. Can. J. Res. 26: 933161. Kidd, J. 1825. On the anatomy of the mole cricket. Philos. Truns. R. Sot. Lond. 115: 20546. Klein, M. and S. W. Applebaum. 1975. The surface morphology of locust hindgut cuticle. J. Entomol. (A) 50: 31-6. Malavasi, J., F. Urefia and Y. Kozuka. 1981a. Microscopica electronica de barridao epitelho digestivo de1 grill0 (Gryllus sp.). Ret?. Biol. Trop. 29: 59-75.
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J., F. Ureiia and Y. Kozuka. 1981b. Estudio ultrastructural de1 epitelio digestive de Taeniopoda y Schistocerca (Saltatoria). Rev. Biol. Trap. 29: 209-26. Muralirangan, M. C. and T. N. Ananthakrishnan. 1974. Taxonomic significance of the foregut armature in some Indian Acridoidea (Orthoptera). Orient. Insect 8: 11945. Nation, J. L. 1983. Specialization in the alimentary canal of some mole crickets (Orthoptera: Gryllotalpidae). Int. J. Morphol. Embryol. 12: 201-10. Richards, A. G. and P. A. Richards. 1979. The cuticular protuberances of insects. Int. J. Morphol. Embryol. 8: 143-57. Snodgrass, R. C. 1993. Principles of Insect Morphology. Cornell University Press, Ithaca, NY. Uvarov, B. 1966. Grasshoppers and Locusts. Cambridge University Press, Cambridge, UK. Malavasi,