Academic Journal of Entomology 6 (1): 20-26, 2013 ISSN 1995-8994 © IDOSI Publications, 2013 DOI: 10.5829/idosi.aje.2013.6.1.73187

Morphological Diversity of Antennal Sensilla in Hopliinae (Coleoptera: Scarabaeoidea: Melolonthidae)

11Angel A. Romero-López, Hortensia Carrillo-Ruiz and 2 Miguel A. Morón

1Escuela de Biología, Benemérita Universidad Autónoma de Puebla, Blvd Valsequillo y Av San Claudio, Ciudad Universitaria, Col. Jardines de San Manuel, Puebla, México 72570 2Red de Biodiversidad y Sistemática, Instituto de Ecología A.C. Carretera antigua a Coatepec 351, El-Haya, Xalapa, Veracruz, México 91070

Abstract: We compare the types of male’s antennal receptors of twenty-four species of the subfamily Hopliinae from Africa, America and Eurasia, based on images obtained by scanning electron microscopy. All species present sensilla of the types chaetica and trichodea on the edges and the distal surfaces of the lamellae. In the proximal surfaces of the middle lamellae we identified sensilla of the types placodea (PLAS), auricilica (AUS) and basiconica (BAS). South African species studied present five PLAS types, four AUS types and six BAS types. In the case of the genus , the Asiatic species present two PLAS types, two AUS types and one BAS type. The Iberian species present three PLAS types, two AUS types and three BAS types. In the North American species we found three PLAS types, four AUS types and four BAS types. In the species that are distributed in Mexico, we observed four PLAS types, four AUS types and three BAS types. The Central American species present three PLAS types, one AUS type and two BAS types. Our results show a great morphological diversity of antennal sensory organs in the Hopliinae subfamily. This diversity is also observed in other species of the Melolonthidae as in the genus Phyllophaga. We discuss the possibility of promoting these morphological traits as a first approach to sexual chemical communication of Hopliinae and its usefulness in the and phylogeny of the group.

Key words: Hopliinae Males Lamellae Sensilla Phylogeny Chemical Communication

INTRODUCTION the Iberian species of the genus Hoplia feed mainly of pollen of Gramineae, Rosaceae, Plantaginaceae, The Hopliinae are represented by species of small to Asteraceae, Malvaceae, Umbeliferae and numerous fruit medium body size (3.5 - 10 mm), with the body covered trees. with scales and setae in variable density, the metatibiae About the anatomy and immature stages, Ritcher [8] normally lacking the apical spurs, the metatarsomere described the larvae of two American species, Hoplia without onychia and with one or two claws and, if two equina LeConte and Hoplia callipyge LeConte, the latter claws, they are unequal in size [1,2]. described by Ritcher [8] as Hoplia cazieri Boyer and In his world catalogue, Dalla-Torre [3] included Hoplia oregona LeConte, now synonyms of H. callipyge sixty-two genera of hopliids, forty-six of these [9]. The larvae of two Iberian species Hoplia philanthus genera are distributed in southern Africa, seven in Fuessly and Hoplia clorophana Erichson has been Eurasia, five in Madagascar, two in India, one in Sri Lanka described by Micó [7] and Carrillo-Ruiz et al. [10] and one in America. Some of the studies for hopliids have described the reproductive system of the females and centered on his food habits, preferences and potential as males of two Mexican species Hoplia squamifera and pollinator of diverse floral species of Asteraceae and Hoplia subcostata Bates. The antennal receptors have Iridaceae [4-6]. One of the most recent works in this sense arisen recently as useful structures in the taxonomy and corresponds to Micó [7], who reported that the adults of phylogeny of Hopliinae [2].

Corresponding Author: Angel A. Romero-López, Escuela de Biología, Benemérita Universidad Autónoma de Puebla, Blvd Valsequillo y Av. San Claudio, Ciudad Universitaria, Col. Jardines de San Manuel, Puebla, México 72570. 20 Acad. J. Entomol., 6 (1): 20-26, 2013

The species of Melolonthidae are characterized by Table 1: Morphological description of each of the types of antennal sensilla observed in the middle lamella of males of the various species lamellate antennae, the lamellate club is formed by studied. extensions of the three to seven terminal segments that are functionally adapted to receive to the chemical stimulus from the air [11,12]. Each lamella from the antennal club contains the sensory organs known as sensilla [13,14]. In the recent years complementary nomenclatures have arisen to that of Meinecke [11], to identify the different types of sensilla in Melolonthidae, one of these nomenclatures use the figure that forms with the exterior cuticle [15,16]. In this nomenclature the basic types of sensilla are placodea, basiconica and coeloconica are considered as the basic types of sensilla in Melolonthidae and other . In particular, the placodea are related with the sexual chemical communication [17,18] and is known that are present in a major density and diversity of forms in the antennae of distal surface and the concave region of each lamella was males than in the antennae of females [14,19]. In particular, called proximal surface. All lamellae were prepared sex pheromone (2-tetradecanona) in H. equina are following the methods proposed by Bozzola and Russell released from females and captured in the sensilla of male [23] for scanning with an electron microscope. Lamellae antennal lamellae [20-22]. were dehydrated in 80%, 90% and absolute ethanol and In the present work we compiled information about dried in a critical-point drier (SAMDRI-780A). They were the morphology of the antennal sensilla of some Hopliinae gold-coated in a metal ionizer (JEOL Model JFC-1100) and species from different regions of the world, with the examined at 15 kV in a scanning electron microscope purpose of (a) to describe and to compare the anatomy of (JEOL JSM-5600LV, 1,000X to 2,000X). The classification the antennal receptors presents in the males species; (b) and the terminology used in this study are according to to determined if the morphology of the antennal receptors [11,15,16,14,24]. shown constancy between these species that maybe could be useful in the taxonomy of the group and (c) to RESULTS relate the morphology of the different types of sensilla of these species with the chemical communication, as has In all species studied were observed trichodea and been suggested in other species of Melolonthidae. chaetica sensilla on the edges and on distal surfaces of all lamellae but it was more evident in the middle lamella MATERIALS AND METHODS (Fig. 1). In the proximal surfaces of these lamellae, were identified the basic type of sensilla placodea (PLAS), We studied specimens from twenty-four species of auricilica (AUS) and basiconica (BAS) (Fig. 2). In general, Hopliinae deposited in the collections of Instituto de in all lamellae of all species studied were found all types Ecología A. C. Xalapa, (IEXA), National Institute of of sensilla and according to their morphology we Biodiversity (INBIO), Canadian National Collection, identified seven types of PLAS, eighth types of AUS and Ottawa (CNC), University of Nebraska State Museum, six types of BAS (Table 1; Figs. 2, 3, 4). Lincoln (UNSM), Museum Nationale d´Histoire Naturelle, In the middle lamellae of the African species (genus París (MNHN) and private collection of M. A. Morón, Odontoplia, Echyra, Amorphochelus, Gymnoloma, Xalapa, Mexico (MXAL) (Table 1). Lepithrix, Pachycnema and Scelophysa) we identified Dried specimens were softened with water vapor. We types of PLAS, four types of AUS and five types of BAS studied only male specimens and for practical we (Tables 1-2; Fig. 3). In the lamellae of the different species considered one specimen for each species. We obtained of Hoplia studied we found PLAS types I, II, III,V, VI, VII; the antennal club that is composed by three lamellae, the AUS types, II, III, IV, VI, VII, VIII and BAS types I, II, IV, further away from the head of the specimen was called VII, VIII (Tables 1-2; Fig. 4). For the lamellae of the Iberian distal lamella, the nearest one was called proximal lamella species of Hoplia we observed three types of PLAS, two and the lamella between distal and proximal was called types of AUS and three types of BAS. In the lamellae middle. Also, the convex region of each lamella was called of North American species we observed

21 Acad. J. Entomol., 6 (1): 20-26, 2013

Table 2: Antennal sensilla types identified in Hopliinae species distributed in distinct regions. PLAS BAS AUS Species Distribution I II III IV V VI VII I II III IV V VI VII VIII I II III IV VI VII Odontoplia alluandi Fairmaire 1897 MAD XX X Echyra oberthuri Lacroix 1997 MAD X X X XX Amorphochelus retusus Klug MAD X X X X XX Gymnoloma femorata Burmeister 1844 SUD X X X Lepithrix fulvipes Thunberg 1818 SUD X XX Pachycnema calcarata Burmeister 1844 SUD XX Pachycnema squamosa Burmeister 1844 SUD X X X Scelophysa pruinosa Burmeister 1844 SUD X X Hoplia moerens Waterhouse 1875 JAP XX XX X Drury 1773 SPA XX X XX Hoplia clorophana Erichson 1848 SPA X XX Hoplia dispar LeConte,1880 USA X XX X XX Hoplia equina LeConte 1880 USA XXX XX Hoplia modesta Haldeman 1843 USA, CAN XXX X Hoplia mucorea Germar 1824 USA X XX XXX Hoplia sackeeni LeConte 1880 USA, CAN X X X XX Hoplia trivialis Harold 1869 USA X XX X Hoplia callipyge LeConte 1856 USA, CAN X XX Hoplia asperula Bates 1887 MEX X X X XX Hoplia subcostata Bates 1887 MEX X X X Hoplia squamifera Burmeister 1844 MEX XX X XX Hoplia festiva Burmeister 1844 MEX X XX X X Hoplia argyritis Bates 1887 CR, NIC X X X XX Hoplia surata Bates 1887 CR XX X XX MAD= Madagascar; SUD= South Africa; JAP= Japan; SPA=Spain; USA= United States; CAN= Canada; MEX= Mexico; CR= Costa Rica; NIC= Nicaragua. PLAS= placodea sensilla; AUS= auricilica sensilla; BAS= basiconica sensilla

Fig. 1: Middle lamella of Amorphochelus retusus showing Fig. 2: Types of sensilla located on the inner surface of two types of mechanoreceptors sensilla. the middle lamella of Hoplia surata. PLAS= CHS= chaetica sensillum; TRS= trichodea placodea sensillum (PLAS I); AUS= auricilic sensillum. sensillum (AUS VII); BAS= basiconic sensillum (BAS I). three types of PLAS, four type of AUS and four types of BAS; in species from Central America we found three From all studied species, fifteen presented PLAS type types of PLAS, one type of AUS and two types of BAS. I and fifteen species presented BAS type I (Table 2). In Mexican species we observed in their lamellae four In the species that are distributed in Madagascar, only E. types of PLAS, four types of AUS and three types of BAS oberthuri and A. retusus presented the same two types of (Tables 1-2, Fig. 4). sensilla (PLAS I and BAS I). The South African species

22 Acad. J. Entomol., 6 (1): 20-26, 2013

Fig. 3: Types of sensilla located on the inner surface of the middle lamella of African species. (A) Amorphochelus retusus (B) Gymnoloma femorata, (C) Pachynema squamosa, (D) Odontoplia alluandi. PLAS= placodea sensilla; AUS= auricilic sensilla; BAS= basiconic sensilla.

Fig. 4: Types of sensilla located on the inner surface of the middle lamella of species of Hoplia, distributed in distinct regions. (A) Hoplia clorophana (Spain); (B) Hoplia mucorea (USA); (C) Hoplia sackeeni (USA); (D) Hoplia asperula (Mexico). PLAS= placodea sensilla; AUS= auricilic sensilla; BAS= basiconic sensilla. do not share any type of antennal receptor, while the species (H. dispar, H. equina, H. modesta, H. trivialis, Asian species (H. moerens) and European species H. mucorea and H. callipyge) presented AUS I; three (H. coerulea) presented the same three types of sensilla (H. equina, H. modesta and H. trivialis) species presented (PLAS I, AUS I and BAS I), which are also presented in AUS II and four species (H. dispar, H. equina, H. modesta some species of Hoplia distributed in North and Central and H. mucorea) presented AUS IV. The BAS I are America. From the species that are distributed in presented in five species (H. dispar, H. equina, H. North America, four of them (H. dispar, H. sackeeni, mucorea, H. trivialis and H. callipyge) and the BAS IV H. trivialis and H. callipyge) presented PLAS I; six are presented in three species (H. equina, H. mucorea

23 Acad. J. Entomol., 6 (1): 20-26, 2013 and H. sackeeni). In Mexican species, three of them Dasylepida ishigakiensis Niijima et Kinoshita [29]. (H. subcostata, H. squamifera and H. festiva) presented For species distributed in Mexico, only has the type AUS I, which is presented too in five North information on types and numbers of sensilla on American species, in one species from Central America, in members of the genus Phyllophaga [14], [19]; in two one Asian species, in one European species and in one species were confirm that exist sexual dimorphism at this species from Madagascar (Table 2). The BAS I is level, either in relation to the number and distribution of presented in many species of hopliids including sensilla in Phyllophaga obsoleta Blanchard [14] or three Mexican species (H. asperula, H. subcostata and different types of receptors found in Phyllophaga ravida H. squamifera) and in the two species distributed in Blanchard [19]. Central America. While the BAS II is presented in two We considered continue the exploration of these Mexican species (H. subcostata and H. squamifera), in lamellar characters in other species and in the females of one species from North America and in one species from hopliids, opening the possibilities to use this information Madagascar. Finally, the species from Central America and related with general knowledge of the sex chemical presented PLAS I, PLAS II and BAS IV. communication in these insects. And finally, the data obtained improve their use as taxonomic characters to use DISCUSSION in cladistics analysis.

The results obtained in the present work show two ACKNOWLEDGEMENTS important focuses regarding the types of sensilla: these structures are useful in the taxonomy and phylogeny of We thank Bruce Gill (Canada Deparment of the group and the data suggest some away for the Agriculture), H. Howden and F. Genier (Canadian relation of the morphology of the sensilla with the sexual Museum of Nature) and Canacol Foundation for their behavior of the hopliids. On the first focus, we found invaluable support and funding for the study of evidence that the types of antennal receptors could be collections deposited in Ottawa. M.L. Jameson and B.C. support some subgroups inside the hopliids studied. For Ratcliffe (UNSM) for their support for the study of the example, the types AUS II, AUS IV and BAS IV were collection at the State Museum of the University of presented in a great number of the species of the genus Nebraska. R.P. Dechambre (Museum National d´Histoire Hoplia studied and these sensilla were presented in all Naturelle, Paris) for the loan of specimens from species that distributed in North America. The type BAS Madagascar. T. Laez (INECOL) obtained images with the II was presented in two species of Mexico. On the second scanning electron microscope. This article is a focus, these data may be useful to understanding the sex contribution to the research project "Systematics and chemical communication of these species, as it has come Biogeography of the genus Hoplia" supported by realizing with other genus of the Melolonthidae PROMEP (103.5/09/7139) and a contribution to the [13,14,16,19] and with H. equina [20]. As observed in research line “Coleoptera Lamelicornios de América species of Phyllophaga, the fact that some types of Latina” supported by Instituto de Ecología (account 902- sensilla are densely present in male antenna than in female 08-011). may be an element that could be extrapolated with the activities of emission-reception of chemical signals of REFERENCES these insects (subject to revision of the lamellae of females). 1. Arnett, R.H. Jr. 1973. The of the United States. The first morphological descriptions for A manual for identification. The American Melolonthidae antennal receptors are attributed to Entomological Institute. Ann Arbor, Michigan, Meinecke [11], being, as to all matters relating to the pp: 1112. subject, the starting point for studies of sensilla in the 2. Carrillo-Ruiz, H. and M.A. Morón, 2006. Study on the group. Hence have arisen as references for various phylogenetic relationships of the Hopliids species Phyllopherta horticola Linnaeus [25], (Coleoptera: Scarabaeoidea). Proceedings of the Adoryphorus couloni Burmeister [26], Paranomala Entomological Society of Washington, 108: 619-638. cuprea Hope [17], Phyllopherta diversa Waterhouse [27], 3. Dalla-Torre, K.W., 1912-1913: Coleopterorum Popillia japonica Newman [18], Phyllophaga anxia Catalogus, , (IV). Vol. LeConte [16], Cotinis nitida Linnaeus [28] and XX, pp: 450. Pars 45.

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