PHYLOGENETIC RELATIONSHIPS AND DISTRIBUTION OF THE RHIZOTROGINI (COLEOPTERA, SCARABAEIDAE, MELOLONTHINAE) IN THE WEST MEDITERRANEAN

In this paper, the West Mediterranean genera of Rhizotrogini are reviewed. Two kinds of character sets are discussed: those relative to the external morphology of the adult and those of the male and female genitalia. Genera Amadotrogus Reitter, 1902; Amphimallina Reitter, 1905; Amphimallon Berthold, 1827; Geotrogus Guérin-Méneville, 1842; Monotropus Erichson, 1847; Pseudoapeterogyna Escalera, 1914 and Rhizotrogus Berthold, 1827 are analysed: to demonstrate the monophyly of this group of genera; to asses the realtionships of these taxa; to test species transferred from Rhizotrogus to Geotrogus and Monotropus, and to describe external morphological and male and female genitalic characters which distinguish each genus. Phylogenetic analysis leads to the conclusion that this group of genera is monophyletic. However, nothing can be said about internal relationships of the genera, which remain in a basal polytomy. Some of the species tranferred from Rhizotrogus are considered to be a new genus Firminus. The genera Amphimallina and Pseudoapterogyna are synonymized with Amphimallon and Geotrogus respectively.

The taxonomic discussion is based on external morphology and male genitalia.The morphology of female genitalia varies little from one to another in the studied taxa and gives few diagnostic characters of low taxonomic rank (Coca-Abia & Martín-Piera, 1991;Martín-Piera & Coca-Abia, 1992).
The procedure for preparation of male genitalia was as follows; first, the clearing of the tegmen and endophallus with hot water and potasium hydroxide (KOH 5%).Once cleaned, a sagittal cut is made in the endophallus face opposite the tigilla.Then, the endophallus was dehydrated in steps using mixtures of increasing percentages of ethyl alcohol and, finally, pure xylol.The endophallus was finally mounted in Canadian Balsam on a microscope slide.
The preparation of female genitalia for study was the same as that for male genitalia, but the dehydration was less.The female genitalia were mounted in Euparal on a microscope slide.
The phylogenetic analysis was carried out using PAUP 3.1.1(Swofford, 1993) and MacClade 3.01 (Madison and Madison, 1992).The exhaustive search was used to find the most parsimonious trees.The robustness of the clades was assessed with bootstrapping (Felsenstein, 1985).
All taxa which were thought to belong to the clade constituted by Amadotrogus, Amphimallina, Amphimallon, Geotrogus, Monotropus, Pseudoapterogyna and Rhizotrogus (Coca-Abia, 1995) were included in the analysis.Geotrogus and Pseudoapterogyna were represented by their type species and the species transferred from Rhizotrogus to Geotrogus (Coca-Abia & Martín-Piera, 1998), except for Geotrogus baudii (Brenske, 1886) which was not included in the analysis because male specimens were not studied.For Amphimallon, two more representative species, one of them the type species, were selected, which express the taxon's variability (Mountreuil, 2000).The two species groups of Rhizotrogus (Coca-Abia, 1995;Coca-Abia and Martín-Piera, 1998) were represented by a single species each.Two species of Amadotrogus were included to show the morphological and genitalic variation of that genus (Coca-Abia & Martín-Piera, 2002).Although, in this paper, the rank of interest is the supraspecific, the use of species, rather than a made-up hypothetical groundplan, allows for verification of homology hypotheses and for the testing of the monophyly of the groups.Whenever possible, the type species of the genera were included in the analysis.Although type species of Monotropus (Monotropus nordmanni Blanchard, 1850) was studied and included in the analysis, the type specimens could not be obtai-ned.Also the species transferred from Rhizotrogus to Montropus (Coca-Abia & Martín Piera, 1998) were included in the analysis.

TAXONOMY
DESCRIPTION OF THE GROUP OF GENERA (Fig. 1) Antenna with ten, nine or eight segments; fifth and sixth segments may be partially fused in some species.Antennal club with three segments whose length varies from shorter than funicule to longer than stem.Clypeus shorter than frons, concave and arcuate laterally with anterior margin not strongly sinuate in the middle.Head weakly and closely punctuate and more or less pubescent.Body pubescence varies among species from abundant on body surface (including pygidium) but shorter on elytra than on pronotum and conspicuous around scutellum to being absent.Wing condition may be functional in both sexes; reduced wings in females (micropterism) and functional wings in males; and both sexes with reduced wings.Hind tibiae with lateral carina complete, with or without dorsal spurs and more or less punctate.Metepimeron narrow and with border.Tarsal claws long, slightly bent, and with a slight basal tooth.
The male genitalia correspond to that described by Coca Abia & Martín Piera (1991).The parame-res are tubular-shaped; dorsal surface with a membranous area in the middle, joined and articulated to the phallobase in medial position (Fig. 2).The endophallus is sac-shaped (Fig. 3) or with two caeca (Fig. 4); joined to the parameres apices without intermediate anchorage structures.The epithelium of the endophallus is covered with sensilla of various shapes and sizes.
The female genitalia correspond to that described by Coca-Abia and Martín Piera (1991).In ventral position the genital chamber has two plates termed sternites.In dorsal position there are two small structures named genital palpes.The median oviduct is membranous with wrinkled epithelium; bursa copulatrix with a wider proximal duct (duc-tus bursae) and a distal blister (corpus bursae).Spermatheca joined on the median oviduct independently of the bursa copulatrix: Spermathecal gland meets spermatheca at different positions of its tract.The two pairs of accessory glands have unequal shape and size and one member of each pair is rounded and reduced.
Genus Amadotrogus Reitter, 1902 TYPE SPECIES: Rhizotrogus quercanus Burmeister, 1855 (designated by Baraud, 1992) DIAGNOSIS: Genus review by Coca-Abia & Martín-Piera (2002).Antenna with ten segments; antennal club shorter than the stem and about the same size in both sexes.Pronotal surface glabrous and shiny, with scattered punctures; lateral margin is smooth or slightly serrate anteriorly.Elytra glabrous, shiny, and without striae.Functional wings in both sexes.Antero-dorsal portion of the parameres with dark areas more sclerotized than the remaining part of the parameres.Apices of the parameres robust and rounded, truncated in lateral view.Endophallus with two caeca projected cephalically    TYPE SPECIES: Scarabaeus solstitialis L., 1758.DIAGNOSIS: Antenna with nine segments, exceptionally 8-segmented (Montreuil, 2000), male antennal club longer than the females'.Head smooth, at most with a discontinued carina; coarsely, closely punctuate and pubescent.Pronotal surface with small punctures, reticulated tegument.Pronotal pubescence varies among species from long, erect and dishevelled to shorter, whitish and covering surface homogenously; lateral margin varies from serrate to almost smooth.Meso-and metasternum densely populated with long hair-like setae.Some species with elytra striate, glabrous, or pubescent around scutellum.Functional wings in both sexes.Apices of the parameres sharp.Endophallus sac-shaped, with areas of pointed sensilla and soft raspulae between the tigillum which are delicate and short with the convergent extreme connected with a bridge (Fig. 5A).Female genitalia as that described by Coca Abia & Martín Piera (1991) and Montreuil (2000).
REMARKS: The genus Amphimallina was established on the basis of the number of antennal segments (eight segments) and distal maxillary palpi-shape (Baraud, 1992).The features established to distinguish this taxa from Amphimallon have no meaning because the antennal segment can be fused, giving eight or nine antennal segments in Amphimallon (Mountreil, 2000).That character does not allow to distinguish both gene-     ra.On the other hand, there are not enough studies of the mouth parts of those genera, which would allow to ascertain if the distal maxillary palpi-shape is an autopomorphic character of Amphimallina.External morphology and the male genitalia prove the resemblance of Amphimallon to Amphimallina.The presence of a distal bridge in the tigillum (Fig. 5A), which is a distinctive character of Amphimallon, is shared with Amphimallina.This similarity, together with the phylogenetic position of Amphimallina in the cladogram, allows to conclude that Amphimallina is synonymous with Amphimallon.DISTRIBUTION: Amphimallon is a Palaearctic Melolonthini genus, distributed across the Mediterranean basin, from the Iberian Peninsula and North Africa to Romania, Bulgaria, Greece, Caucases and Russia.
TYPE SPECIES: Geotrogus magagnosci Guérin-Méneville, 1842 DIAGNOSIS: Antenna with ten segments; antennal club shorter than the stem and about the same size in both sexes.Head smooth; scattered punctures.Pronotal surface with small punctures, reticulated tegument.Pronotal surface mainly glabrous or, at most, anterior and posterior edges pubescent; lateral margin smooth.Elytra smooth.Meso-and metatibiae smooth and shiny with scattered punctures.Males with functional wings, females always micropteres and in some species males are micropteres.Dorsal surface of the parameres has a membranous area towards the middle growing wider at the apex (Fig. 6D).Endophallus sac-shaped, without raspulae, with areas of pointed sensilla and strong tigillum (Figs.5G, 7).Female genitalia as described by Coca Abia & Martín Piera (1991).
REMARKS: Geotrogus and Pseudoapteregyna have been considered to be independent taxa.The features established to distinguish one from the other are the wing condition (Baraud, 1985), elytrashape and coxa-size.The loss of wings is an adaptation to desert environment.It can be seen in other species which inhabit the desert, such as the subgenus Eugastra found in Arizona.The loss of wings has led to some morphological changes of elytra    (c) Sociedad de Amigos del Museo Nacional de Ciencias Naturales y Consejo Superior de Investigaciones Científicas Licencia Creative Commons 3.0 España (by-nc) http://graellsia.revistas.csic.esand coxae.These characters are the consequence of an adaptation to the environment and must not be considered as good diagnostic characters.On the other hand, the external morphology of other, nonadaptive, characters and the male genitalia prove the resemblance between both taxa.Consequently, Pseudoapterogyna is synonymous with Geotrogus.
DIAGNOSIS: Antenna with eight segments; antennal club longer than the stem and male antennal club longer than the females'.Pronotal surface glabrous or pubescent; serrated lateral margin.Elytra weakly striated.Functional wings in both sexes.Apices of the parameres robust.Endophallus sacshaped, without raspulae, with areas of pointed sensilla and without tigillum (Fig. 5Mt).Phallobase ventrally sclerotized and closed and strongly sinuate in the middle.Female genitalia as that described by Coca Abia & Martín Piera (1991).
REMARKS: The phylogenetic analysis below does not allow to confirm that those transferred from Rhizotrogus by Coca-Abia & Martín-Piera (1998) are established as a species belonging to Monotropus.Neither, can these species be assigned to other genera, so they remain as incerte sedis.
DIAGNOSIS: Antenna with ten segments; male antennal club longer than females' and as long as the stem.Head smooth, at most with a discontinued carina; coarsely, closely punctuate and pubescent.Pronotal surface with scattered or closely-spaced punctures.Pronotal pubescence varies among the species, from long, erect and dishevelled to shorter; serrate lateral margin.Elytra glabrous or pubescent around scutellum.Meta-and mesotibiae with spurs in dorsal position.Functional wings in both sexes.Strong parameres.Endophallus sac-shaped, with areas of pointed sensilla and thick raspulae between the tigillum, which are strong (Figs. 3 and 5Rh).Female genitalia as that described by Coca Abia & Martín Piera (1991).
DIAGNOSIS: Antenna with ten segments; antennal club shorter than the stem and about the same size in both sexes.Head smooth, coarsely, closely punctuate and more or less pubescent.Pronotal surface with scattered or closely-spaced punctures.Pronotal pubescence varies among species, from long, erect and dishevelled, to shorter or glabrous; smooth lateral margin.Elytra glabrous or pubescent.Meta-and mesotibiae without spurs in dorsal position, shiny with scattered punctures.Functional wings in both sexes.Apices of the parameres blunt.Parameres shorter than the phallobase and laterally sinuate (Fig. 8).Endophallus sac-shaped, with areas of pointed sensilla and without raspulae, strong and large tigillum (Fig. 9), almost as long as the sac.Female genitalia as that described by Coca-Abia & Martín Piera (1991).
ETYMOLOGY: The genus name is dedicated to Dr. Fermín Martín-Piera, professor and fellow of the author.His enthusiastic participation in Melolonthinae beetle research inspired the life work of the author and a love for these insects.
REMARKS: The species Rhizotrogus punicus (Burmeister, 1855) is considered type species of the genus Firminus.A male of this species, placed in Martin-Luther-Universitat Halle-Wittenberg (Saale),

PHYLOGENETIC ANALYSIS
The analysis using equal weights yielded five equally parsimonious cladograms, each with 44 steps, consistency index (CI) of 0.864, and retention index (RI) of 0.910.Two rounds of successive weighting (base weight 1000) yielded five trees of a length of 360 steps, CI = 0.944 and RI = 0.962.
The genera Amphimallon and Rhizotrogus are strongly supported, with a bootstrap of 93% and 78% respectively.Also, Amphimallina is related to Amphimallon, seen to be constituting the same taxon with considerable support (bootstrap 69%).
The genus Amadotrogus shows significant support in its branch (bootstrap 97%) that confirms the existence of autopomorphic characters established by Coca-Abia & Martín-Piera (2002).
Species formerly transferred from Rhizotrogus to Monotropus (Coca-Abia & Martín-Piera, 1998) lack synapomorphies which would justify their inclusion in Monotropus.Neither do these species constitute a monophyletic group but rather make up a basal polytomy.-Piera, 1998), and by Pseudoapterogyna tusculus type species of the genus Pseudoapterogyna.The phylogenetic position of this taxa in the cladogram, together with morphological and genitalic features currently used as taxonomic characters, allow herein to establish Pseudoapterogyna as synonymous with Geotrogus.

Martín
Whereas the remaining species transferred from Rhizotrogus to Geotrogus constitute a clade, which herein is considered a new genus Firminus, supported by synapomorphic character in the edeagus (15).
Amphimallina is related to Amphimallon, that allows to establish Amphimallina as synonymous taxon with Amphimallon.
The species formerly transferred from Rhizotrogus to Monotropus (Coca-Abia & Martín-Piera, 1998) do not constitute a monophyletic group, they can not be considered belonging to Monotropus remaining as incerta sedis.
Finally, the analysis allow to consider the West Mediterranean genera Amadotrogus, Amphimallon, Firminus, Geotrogus, Monotropus and Rhizotrogus a monophyletic group but does not shed light on their phylogenetic relationships.This basal polytomy could be considered from two points of view, either from that of "soft" polytomy or "hard" polytomy (Coddington & Scharft, 1996).Seen from the first point, the lack of data in the external morphology and genitalia does not lead to a solution; some other methodology, such as molecular analyses would be necessary.From the second point, it could be that basal radiation led to the diversification of the Rhizotrogini in the West Mediterranean.

Fig. 10 .
Fig. 10.-Bootstrap 50% Majority-rule consensus tree.The numbers on the branches indicate the bootstrap support.