Zoomorphology (2011) 130:289–303 DOI 10.1007/s00435-011-0134-z ORIGINAL PAPER Comparative morphology of the male genitalia of Aphididae (Insecta, Hemiptera): part 1 Karina Wieczorek • Bartosz J. Płachno • Piotr S´wia˛tek Received: 4 February 2011 / Revised: 29 July 2011 / Accepted: 12 August 2011 / Published online: 28 August 2011 Ó The Author(s) 2011. This article is published with open access at Springerlink.com Abstract The present study provides new data concern- Introduction ing the morphology of the male genitalia of Aphididae and unifies their nomenclature. The structure of the male gen- Among Hemiptera, Aphidoidea have a special status italia of 31 species from 26 genera of Aphididae was because of their high polymorphism and distinctive mode studied with light and scanning electron microscopy. In the of reproduction—cyclical parthenogenesis. In the complete studied species, the genitalia of males consist of a phallus life cycle (holocycle) of most aphids, the parthenogenetic composed of the sclerotized basal part with its articulation phase ends with the appearance of sexuales—oviparous and a membranous apical part—an aedeagus. Laterally of females and males. In most species, the sexual forms the phallus, there is a pair of setose parameres. The shape appear in autumn; rarely earlier, at the beginning of the of the aedeagus, the shape and length of the sclerotized summer. Daylength, temperature and nutrition are the most basal part and its articulation as well as the variability of important factors, which influence the production of sex- parameres in their form and the number of setae are rec- uales (Kawada 1987). ognized as important systematic signs of the genitalia. In comparison with females, aphid males are slender and These characters are considered in conjunction with the characterized by numerous rhinaria on the antennal seg- phylogenetic relationships among the studied taxa. ments III and IV, shorter cauda, visible sclerotization on the abdomen and sclerotized genital structures. Males, Keywords External reproductive system Á Insects Á SEM winged or wingless, are also less numerous and smaller than females. If they are less than 50% of female size, they are considered to be dwarfs (Vollrath 1998). The structure of the male internal reproductive system has been studied in about 80 species so far (Vitlaczil 1882; Blochman 1887;Cholodkovsky1900; Wojciechowski 1977; Communicated by T. Bartolomaeus. Klimaszewski et al. 1973; Głowacka et al. 1974a, b; Bochen et al. 1975; Polaszek 1987a, b in lit.; Wieczorek and Woj- & K. Wieczorek ( ) ciechowski 2004;Wieczorek2006, 2008; Wieczorek and Department of Zoology, University of Silesia, ´ Bankowa 9, 40-007 Katowice, Poland Swia˛tek 2008, 2009), and these studies have made an e-mail: [email protected] important contribution to unravelling the phylogeny of Aph- ididae. However, in contrast to others groups of Hemiptera, B. J. Płachno the male genitalia of Aphididae have only been used margin- Department of Plant Cytology and Embryology, Jagiellonian University, Grodzka 52, 31-044 Cracow, Poland ally in their taxonomy and classification (Essig and Abernathy e-mail: [email protected] 1952; Iglischand Sobhani1972; Sobhani and Iglisch 1972)and have never been documented in a comparative study. Only ´ P. Swia˛tek Polaszek (1987b in lit.) reviewed these structures and revealed Department of Animal Histology and Embryology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland a number of characters which are of potential use in the phy- e-mail: [email protected] logeny and higher classification of Aphidoidea. 123 290 Zoomorphology (2011) 130:289–303 The male genitalia of aphids are relatively large and less reduced parameres. Heie (1980) described only a sin- discernible under a hand lens or even with the naked eye gle pair of structures that he termed parameres or claspers, and are composed of the median intromittent organ (the with the aedeagus having a sclerotized basal part; while phallus) and 2 pairs of sclerotized appendices located lat- according to Miyazaki (1987), both of the pairs of appen- erally of the phallus. Nevertheless, the nomenclature and dices are called valves, claspers or parameres. Yang and drawings of these appendices are a source of confusion (see Chang (2000) comprehensively investigated the external Table 1). In general description of the male genitalia of male genitalia in Hemiptera. According to these authors, Aphidoidea Ossiannilsson et al. (1970) recognized claspers the male genitalia of aphids [based on the study of a single or opercula lateral to the penis, and the sclerotized basal species, Periphyllus koelreuteriae (Takahashi, 1919)] part of the penis consists of a pair of valves, whereas consist of the aedeagus, phallobasal plates with distinct Matsuda (1976) mentioned the tubular penis and more-or- cone-shaped projection—a connective directly connected Table 1 Comparison of the terms for male genitalia in Aphidoidea applied so far and proposed in the present paper Terms used in the Phallus Parameres present paper Basal part Articulations of basal part Aedeagus (penis) (sclerotized) (proximal and distal part (membranous) of sclerotized arms) Balbiani (1869) Valves -?Claspers Macrosiphoniella millefolli (De Geer, 1773) Baker (1915) Large, fan-shaped structures -?Claspers Eriosoma lanigerum (Hausmann, 1802) Essig and Abernathy (1952) Supporting plates Coriaceous ring ? Harpagones (gonapophyses) Periphyllus species Takahashi (1960) ---Claspers Aiceona japonica Takahashi, 1960 Sorin (1965) Basal sheath -?Claspers Stomaphis species Ossiannilsson et al. (1970) Valves -?Claspers (opercula) Aphidoidea, generally Iglisch and Sobhani (1972), ? ‘‘Sclerotized fastener’’ ?? Sobhani and Iglisch (1972) Macrosiphoniella species Matsuda (1976) --?Reduced parameres Aphidoidea, generally Heie (1980) ?-?parameres (claspers) Aphidoidea, generally Miyazaki (1987) --?parameres (claspers, valves) Aphidoidea, generally Polaszek (1987b in lit.) Valves -?Claspers comparative study of Aphidoidea Blackman et al. (2001) Valves -?Claspers Trama troglodytes von Heyden, 1837 Favret et al. (2004) Apophyses -?Claspers Iowana frisoni Hottes, 1954 Grimaldi and Engel (2005) Reduction in or a loss of male genitalia Aphidoidea, generally ? Structure described as the same name as in the present paper; - structure not described 123 Zoomorphology (2011) 130:289–303 291 with genital styles. The phallobase and the connective form were borrowed from the Department of Zoology, Univer- the upper half-circle-shaped periandrium, and this structure sity of Silesia, Katowice, Poland. Because of the rarity of is hypothetically considered to be a primary characteristic males, sample sizes consisted of 10 studied individuals for among hemipterans. Grimaldi and Engel (2005) mentioned each species, with exception of M. spinifer, L. ocoteae and that Aphidomorpha have a reduction in or even a loss of P. passerini which were studied from 3-4 specimens only. male genitalia. Generally, these structures were believed to The genitalia of 31 species were studied from aphid be similar across species and not useful taxonomically. material preserved in alcohol and slide-mounted specimens Because numerous terms have been applied to the var- (LM); 9 species were also observed using SEM techniques; ious components of the external male genitalia of Aphidi- nymphs and adult males of Appendiseta robiniae (Gillette, dae, our study firstly standardizes the terminology. We 1907) were prepared for semi-thin sectioning. Collection used light (LM) and scanning electron microscopy (SEM) data and the microscopic techniques used are summarized to show the detailed structure of the male genitalia, i.e., the in Table 2. phallus composed of the sclerotized basal part with its articulations (proximal and distal arm), the membranous Light and electron microscopy apical part—aedeagus and parameres (see Table 1). In the present paper, the general morphologies of these Alcohol-preserved specimens and slides were examined structures are described and compared in those represen- and photographed using the light microscope Nikon tatives of the Aphididae in which the genitalia are not Eclipse 600. Drawings were made with a camera lucida. A modified. This paper is part of a larger study into the magnified view is provided for each of the photographs and phylogeny of the Aphididae will provide new data con- drawings. Additionally, the nymphs and adult specimens of cerning the morphology of the male genitalia in selected Appendiseta robiniae were fixed for 2 h with 2.5% glu- species of Aphididae (subfamilies: Aiceoninae, Anoecii- taraldehyde in a 0.1 M phosphate buffer (pH 7.4), then nae, Eriosomatinae, Hormaphidinae, Greenideinae, Lach- washed 5 times in a phosphate buffer, postfixed for 2 h in ninae, Mindarinae and Thelaxinae), Adelgidae and 1% OsO4 in the same buffer, dehydrated in a graded series Phylloxeridae—i.e. representatives of aphids with strongly of ethanol replaced by acetone and then embedded in an modified structures of the male genitalia. Epoxy Embedding Medium Kit (Sigma). Semi-thin sec- tions (0.8 lm thick) were cut on a Leica Ultracut UCT ultramicrotome, stained with methylene blue and examined Materials and methods under an Olympus BX60 microscope equipped with a DP12 digital camera and AnalySIS 3.2 (Soft Imaging Taxon sampling System) software. The procedure for preparing samples for SEM was as The structure of the male genitalia of 31 species belonging described earlier (Płachno and S´wia˛tek