© Entomologica Fennica. 3.XII. l990 A phenetic study of the genus Rasahus Amyot & Serville (Heteroptera, Reduviidae) Maria del Carmen Coscaron Coscar6n, M. C. 1990: A phenetic study of the genus Rasahus Amyot & Serville (Heteroptera, Reduviidae).- Entomol. Fennica I: 131 - 144. Cluster analysis by four methods and a principal component analysis were performed using data on 24 morphological characters of27 species of the genus Rasahus (Peiratinae). The results obtained by the different techniques show general agreement. They confirm the present number of taxa and reveal the existence within the genus of three groups of species: scutellaris, hamatus and vittatus. The scutellaris group is constituted by R. aeneus (Walker), R. macu­ lipennis (Lepelletier and Serville), R. bifurcatus Champion, R. castaneus Coscar6n, R. guttatipennis (S t<ll), R. flavovittatus Stat, R. costarricensis Coscar6n,R. scutellaris (Fabricius), R. atratus Coscar6n, R. peruensis Coscar6n, R. paraguayensis Coscar6n, R. surinamensis Coscar6n, R. albomaculatus Mayr, R. brasiliensis Coscar6n and R. sulci col/is (Serville). The hamatus group contains R. rufiventris (Walker), R. hamatus (Fabricius), R. amapaensis Coscar6n, R. arcitenens Stal, R. limai Pinto, R. angulatus Coscar6n, R. thoracicus Stal, R. biguttatus (Say), R. arcuiger (Stat), R. argentinensis Coscar6n and R. grandis Fallou. The vittatus group contains R. vittatus Coscar6n. The characters used to separate the groups of species are: shape of the pygophore, shape of the parameres, basal plate complexity, shape of the postocular region and hemelytra pattern. Illustrations of the structures of major diagnostic importance are included. Marfa del Carmen Coscar6n, Division Entomologfa, Facultad de Ciencias Naturales y Museo de La Plata, Paseo del Bosque SIN, 1900 La Plata, Argentina (Temporary address: Zoological Museum, University of Helsinki, P. Rautatiekatu 13, SF-00100 Helsinki, Finland) 1. Introduction relationships of its species are still very unclear. The present study was undertaken because it was At present, the genus Rasahus consists of 27 thought that numerical techni ques could profita­ species with Nearctic and Neotropical distribu­ bly be applied to quantify the taxonomic distance tion. between the species of the genus and to determine The systematics of this genus has recently the relation between the characters and their dis­ been revised (Coscar6n 1983), but the phenetic criminatory values. 132 Coscar6n: Th e genus Rasahus • ENTOMOL. FENNICA Vol. 1 2. Material and methods Humboldt Universitat zu Berlin (D.D.R.), Mr. Martinez (personal collection). The numerical techniques used follow Crisci & L6pez-Armengol (1983). 2.2. Selection of the characters 2.1. Selection of the Operational Taxonomical The character set is composed of features of the Units (OTU's) external morphology of the body and the male genitalia. In this study the 27 species of Rasahus constitute The te1minology used for the external mor­ the operational taxonomic units (OTU's). They phology is according to Lent & J m·berg ( 1966) are: R. aeneus (Walker) (OTU 1), R. maculipennis and Lent & Wygodzinsky ( 1979). The terminol­ (Lepelletier and Serville) (OTU 2), R. rufiventris ogy employed for the characters of the male (Walker) (OTU 3),R. bifurcatus Champion (OTU genitalia is that proposed by Dupuis (1955, 1963) 4), R.flavovittatus (StaJ) (OTU 5), R. guttatipen­ and Davis (1966, 1969). The methodology for nis (Still) (OTU 6) , R. atratus Coscar6n (OTU 7), extraction, dissection, inflation and drawings of R. arcitenens Stal (OTU 8), R. arcuiger (Still) the male genitalia has been explained elsewhere (OTU 9) , R. argentinensis Coscar6n (OTU I 0), R. (Coscar6n 1983). Figs. 1- 24 and 29-49 depict the grandis Fallou (OTU 11), R. limai Pinto (OTU characters used in the study. 12), R. th oracicus Still (OTU 13), R. vittatus Characters of the female genitalia are not used Coscar6n (OTU 14), R. amapaensis Coscar6n in this paper because there is a significant number (OTU 15), R. hamatus (Fabricius) (OTU 16), R. of species for which the females are still un­ biguttatus (Say) (OTU 17), R. surinamensis Cos­ known. car6n (OTU 18), R. albomacu/atus (Mayr) (OTU The characters of the external morphology 19), R. peru ensis Coscar6n (OTU 20), R. para­ number 18 and those of the male genitalia 6. guayensis Coscar6n (OTU 21), R. brasiliensis The set includes quantitative continuous char­ Coscar6n (OTU22),R. sulcicol/is (Serville) (OTU acters (3), ratios (7) and qualitative characters 23), R. scutellaris (Fabricius) (OTU 24), R. cas­ (14). For each species (OTU), 5 males were taneus Coscar6n (OTU 25), R. angulatus Cos­ measured (when possible) and the mean value was car6n (OTU 26) and R. costarricensis Coscar6n used. Indications of how the measurements were (OTU 27). made are given in Figs. 1- 19. The material examined belongs to the follow­ The coding was based on the kind of data. For ing in stitutions: The American Museum of Natu­ quantitative data and ratios the value is given; ral History (U.S.A.), British Museum (Natural qualitative data are coded as absent (0) or present History) (England), California Academy of Sci­ (1 ), or, if multistate, as 1, 1.5 or 2. ences (U.S.A.), Canadian National Collections of The characters, character states and coding are Insects, Arachnids and Nematodes (Canada), listed below. Fundaci6n Miguel Lillo (Argentina), Institute Entomol6gico San Miguel (Argentina), Museo A. Characters from external morphology Argentino de Ciencias Naturales (Argentina), Museo de Ciencias Naturales La Plata (Argen­ 1 Total length (Fig. 1) tina), Museo Emilio Goeldi (Brasil), Museum 2 Width of pronotum (Fig. 1) National d'Histoire Naturelle (France), Museu de 3 Width of abdomen (Fig. 1) Zoologfa de Sao Paulo (Brazil), Naturhistoriska 4 Width of head/length of head (at eye hei ght) Riksmuseet (Sweden), Rijksmuseum van (Fig. 1) Natuurlijke Historie en Geologie (The Nether­ 5 Length pronotum/length head (Fig. 1) lands), Snow Entomological Museum, University 6 Length postocular region/length anteocular of Kansas (U.S.A.), United States National Mu­ region (Fig. I) seum (U.S.A.), Universitetets Zoologiske Mu­ 7 Length rostral segment II/length rostral seg­ seum (Denmark), Zoologisches Museum, der ment I (Fig. 2) ENTOMOL. FENNICA Vol. 1 • Coscar6n: The genus Rasahus 133 8 Length rostral segment III/length rostral 22 Medial process of pygophore: length/width segment I (Fig. 2) (Fig. 19) 9 Height of head/eyes height (Fig. 2) 23 Parameres I 0 Body shape (1 ) subrectangul ar (Fig. 2 1) (1 ) stout (Fig. 37) (2) subtriangular (Fig. 22) (2) slender (Fig. 34) 24 Basal plate 11 Postocul ar region (1) simple (Fig. 23) (1 ) angul ar (Fig. 3) (2) complex (Fig. 24) (2) rounded (Fig. 4) 12 Eye position Once the data for each of the taxa had been ( 1) not surpassing nor under nor upper sur­ recorded, a basic data matri x was constructed for face of head (Fig. 2) 27 OTU's fo r 24 characters (Table l ). (2) surpassing under or upper surface of head or under and upper surface of head (Fig. 6) 2.3. Data processing 13 Scutellum (1) not acuminate or very slightly acumi­ The data were analysed by five methods, using nate (Fig. 7) four cluster analyses and one ordinati on, as shown ( 1. 5) acuminate in the flow chart (Fig. 25). The computati onal (2) very acuminate (Fig. 9) work was done at the Centro de Estudios Superi ­ 14 Hind femur coloration ores para el Procesamiento de Ia Informacion (1 ) uniform (Fig. 34) (CESPI) of the University of La Plata, using NT­ (2) more than one colour (Fig. 29) SYS programs. 15 Hemelytra with a well defined oval dot over The BDM was standardized (BDMS) by the Cu characters, to remove the unequal weights im­ (0) absence (Fig. 44) posed on it by the use of different scales of (1) presence (Fig. 42) measurement. Details of the method and compu­ 16 Conexivum tational procedures may be found in Sneath & ( 1) vi sible dorsall y (Fig. 29) Sokal ( 1973) (2) not vi sible dorsally (Fig. 37) 17 Conex ivum Cluster analysis ( 1) homogeneous (Fig. 10 ) (2) not homogeneous (Fig. 11 ) The copheneti c correlati on coefficient (r ) (CCC) 18 Eighth sternite pilosity was computed here as a measure of distortion for (0) absent (Fig. 12) each of the methods used. (1 ) present (Fig. 13) Method 1. The "Taxonomic Distance Coeffi ­ cient" (S neath & Sokal 1973) pair between the B. Characters from th e male genitalia OTU's and the un weighted Pair-Group Method 19 Shape of pygophore using arithmeti c averages (UPGMA) fo r the con­ ( l ) rounded (Fig. 14) struction of th e phenogram of di stances were ( 1.5) subrectangul ar (Fig. l 5) employed; CCC was also computed. (2) quadrangular (Fig. 16) Meth od 2. A OTU x OTU distance matri x was 20 Inferior edge of pygophore obtained from the BDMS by calculating the (1) straig ht (Fig. 17) "Manhattan distance" between pairs of OTU's. ( 1.5) sinuose (Fig. 18) The distance matrix served as input in the calcu­ (2) with an evaginati on (Fig. 19) lati on of a "Prim Network". 2 1 Median distal region of medial process of Meth od 3 . The same procedure as Method I pygophore was used, except that the similarity coefficient (1) not c urved (Figs. 17, 20) employed here was the Pearson product-moment (2) curved (Figs. 18, 19) correlation coefficient. 134 Coscar6n: The genus Rasahus • ENTOMOL. FENNICA Vol. l ~9 ~ ~78 w.p. 1 . ' ; ' ' I' : \. i : I ' : i ! -------:'- ----------- : ..,........_' ___ _ : ' ~~ ~- -----+ Fig s. 1- 13. Characters of th e external morphology. -1 . Head, pronotum and abdomen, dorsal view (I = length; w.p. = width of pronotum; w.a. = width of abdomen; l. h. =length of head ; w.h. = width of head ; l.p. = length of pronotum; l.ao. = length of anteocular region; l.po. = length of postocular region).- 2. Head , lateral view (1.1.