Size polymorphism in Oncaea venusta Philippi, 1843 and the validity of O. frosti Heron, 2002: a commentary

The morphological characters used to describe Oncaea frosti Heron, 2002 (Copepoda, Poecilostomatoida), an Atlantic medium-sized form variant of O. venusta Philippi, 1843, appear to be inadequate in view of the great polymorphism known for this ubiquitous species. Comparative analysis of published and newly collected length data of O. venusta variants worldwide demonstrates that O. frosti cannot be unequivocally delineated in the Indo-West Pacific. The validity of O. venella Farran sensu Heron (2002) is questioned and comments are given on Heron's synonymization of O. venusta f.venella sensu Ferrari (1975) and sensu Böttger-Schnack (2001) with O. frosti. As long as the significance of the morphological characters used to separate O. venusta form variants is not substantiated by data emerging from alternative taxonomic methods, such as the analysis of gene sequences, the species names O. frosti and O. venella Farran sensu Heron (2002) are regarded as species inquirendae in the genus Oncaea.     

Enantiomeric conservation of the male‐produced sex pheromone facilitates monitoring of threatened European hermit beetles (Osmoderma spp.)

Hermit beetles of the genus Osmoderma (Coleoptera: Scarabaeidae: Cetoniinae) are known for their fruity odour, which is released in large amounts by males. Two species of the genus occur in Europe, the eastern Osmoderma barnabita (Motschulsky) and the western Osmoderma eremita (Scopoli). Previous studies on Swedish populations of O. eremita showed that the compound responsible for the characteristic scent, γ‐decalactone, functions as a sex pheromone for the attraction of conspecific females. Male O. eremita only release the (R)‐enantiomer of the lactone, and both sexes are anosmic to the opposite enantiomer. As the distribution areas of the two hermit beetle species partly overlap, it may be expected that they use different enantiomeric compositions of γ‐decalactone as pheromones to promote species discrimination. This paper reports on the identification of the sex pheromone of O. barnabita. Surprisingly, males from a Polish population produce only the (R)‐enantiomer of γ‐decalactone, and conspecific females show equal attraction to the (R)‐enantiomer and a racemic mixture of the compound, indicating that O. barnabita is anosmic to the (S)‐enantiomer, similarly to what was observed for O. eremita. A mtDNA sequence analysis of the cytochrome oxidase subunit I gene of Polish and Swedish beetles confirmed their taxonomical status as O. barnabita and O. eremita, respectively, with an average sequence divergence of 10.5% between beetles from the two studied areas. Although genetic data suggest that these species diverged several million years ago, they still rely on the same enantiomer of γ‐decalactone for mate finding. Thus, the male‐produced pheromone in Osmoderma spp. may be regarded as a territorial signal being exploited by females, rather than a cue for determining species identity. Our data show that the same compound can be used to facilitate monitoring of both beetle species, which are considered indicator species of the species‐rich fauna of saproxylic insects in Europe.     

The mating systems of three species of minute pirate bug,Orius sauteri,O. minutus,and O. strigicollis

We compared the mating systems and genital morphology of three Orius species dominant in Japan: Orius sauteri (Poppius), Orius minutus (L.), and Orius strigicollis (Poppius) (Heteroptera: Anthocoridae). In all three species, the males were polygamous and could inseminate at least three females at a rate of one female per day. Compared to the other two species, the O. minutus males had a lower rate of success in three consecutive mating orders. The mated females laid the same number of eggs irrespective of mating sequence. Orius minutus and O. strigicollis females were found to be monandrous, and they re‐mated with another male only when the 1st mating failed. In contrast, O. sauteri females were polyandrous and accepted a 2nd male even when the 1st mating was successful. Multiple mating with a single male did not increase their fecundity, and it decreased the hatching success of eggs. Mating with multiple males did not affect the fecundity or hatching success. Our scanning electron microscopy observation suggested that the genitalia of O. minutus and O. strigicollis were more similar in shape. The similarities in mating system and morphology between O. minutus and O. strigicollis support a close phylogenetic relationship.     

Olfactory response towards its prey Frankliniella occidentalis of wild and laboratory‐reared Orius insidiosus and Orius laevigatus

Orius species are important biological control agents of thrips in protected crops. Rearing conditions in mass production facilities may affect their performance in the crop when searching for the target prey. The aim of this study was to evaluate and compare the search behaviour and orientation towards prey of two Orius species, O. laevigatus (Fieber) and O. insidiosus (Say) that have been reared in the laboratory under different conditions, with wild (field‐collected) individuals. Adult predator females were placed in a Y‐tube olfactometer and offered a choice between the odours released by plants of different species (cotton, common bean, sweet pepper and cucumber), which were either non‐infested or infested with Frankliniella occidentalis (Pergande) adults.O. laevigatus and O. insidiosus responded to odours from thrips‐infested plants and these responses were influenced by the origin of the colonies. A larger percentage of laboratory‐reared O. laevigatus females (42%) did not made a choice between thrips‐infested or clean plants, compared with wild individuals (17%). Of those females that did respond to plant odours, a smaller percentage of laboratory‐reared O. laevigatus females (34%) responded to the odours from thrips‐infested plants compared with wild insects (76%). No significant differences were found inO. insidiosus females that did not make a choice between thrips‐infested or clean plants (14% for wild vs. 17% for lab individuals). Also, no significant differences were found between O. insidiosus females that selected thrips‐infested plants at the corresponding proportion of wild (75%) and laboratory‐reared (70%) individuals. We propose that the olfactometer test could be a complementary evaluation aspect to the already developed quality criteria for performance of mass‐reared Orius predators.     

Revision of the termite-parasitizing genus Dicranopteron (Diptera: Phoridae)

Dicranopteron Schmitz is removed from the Metopininae and three new species are described. All species are represented by females only and come from Odontolermes and Macrotermes nests in the Orient. A key:to species) is provided. One species was observed ovipositing in the abdomens of the young stages of O. takensis.     

An analysis of the mechanisms governing species replacements in crayfish

Summary We investigated mechanisms governing replacement of the native crayfish Orconectes sanborni by an invading cryafish, Orconectes rusticus. The two species had similar life histories, habitat preferences, and feeding patterns in allopatric and sympatric stream areas. Orconectes rusticus young-of-year (YOY) grew faster than O. sanborni YOY in the field. Adult O. rusticus were larger and, hence, dominant over adult O. sanborni; YOY were non-aggressive. In laboratory experiments, adult crayfish (about 28 mm carapace length or larger) were not susceptable to predation by largemouth bass (Micropterus salmoides, 30 cm total length) and did not alter shelter use when fish were present. Orconectes rusticus YOY were less susceptible to predation than O. sanborni YOY. Orconectes rusticus YOY reduced their vulnerability to largemouth bass by occupying shelters more often than YOY O. sanborni. In mixed-species mateselection experiments, male O. rusticus and male O. sanborni preferentially mated with O. rusticus females. Inappropriate mate selection in sympatry may have caused the 90% reduction in recruitment for both species in 1982. Orconectes rusticus probably maintains greater population growth than O. sanborni, because (1) more gravid O. rusticus females occurred in sympatry, (2) O. rusticus produced more young than O. sanborni, and (3) O. rusticus young grew faster. Reproductive interference, acting synergistically with differences in aggressive dominance and young-of-year susceptibility to predation, appears to serve as the major mechanisms regulating replacement of O. sanborni by O. rusticus in Ohio streams.     

Reproductive biology of viviparous and oviparous species of the leaf beetle genus Oreina

In five species of the genus Oreina Chevrolat (Coleoptera, Chrysomelidae) we compared the size of offspring, the fecundity of the females, the timing of offspring production and female investment over the season. Two of the species, O. elongata and O. luctuosa, laid eggs, while O. cacaliae, O. gloriosa and O. variabilis gave birth to larvae. Offspring size corrected for female size was similar in the two oviparous species and in the viviparous O. cacaliae. In the two other viviparous species the larvae were two to three times bigger in relation to the female. The greater size of the offspring was not traded off for lower fecundity in these latter two species, yet the production of bigger larvae was associated with a longer laying period and thereby a spreading of reproductive investment over the season. The prediction of life history theory that higher investment in individual offspring should be traded off for lower fecundity could not be confirmed. The investigation of egg and larval development showed that in one of the oviparous species, O. luctuosa, the length of the egg stage was more variable. This corroborates the view that in this species the eggs can be retained for varying times before being laid. Greater size at birth does not necessarily lead to shortened developmental times: the larval periods of O. cacaliae, O. elongata, O. gloriosa and O. variabilis were all comparable although the larvae of the first two species were relatively smaller when laid; only the small larvae of O. luctuosa needed significantly longer for their development. For all growth parameters examined the differences between species were larger than the differences between populations. A comparison of larval growth of the oligophagous species O. cacaliae on three plant genera showed that larval growth rate is influenced by the food plant. However, the plant on which the larvae grew worst is apparently not chosen for oviposition in the field. A comparison with a phylogeny of the species based on allozymes suggests that species with similar reproductive parameters are closely related, yet that viviparity evolved independently in O. cacaliae on one hand and O. variabilis and O. gloriosa on the other.     

Coexistence of ecologically similar colonising species III. Drosophila aldrichi and D. buzzatii: larval performance on,and adult preference for,three Opuntia cactus species

Two Drosophila species, D. buzzatti and D. aldrichi, coexist on several species of Opuntia cacti in Australia, primarily on O. tomentosa and O. streptacantha in the northern part of the cactus distribution, and on O. stricta in the south. Thorax length of field-collected adults was less, and the variance in length greater, than that for flies reared on simulated rots in the laboratory, indicating that these species are affected by crowding in nature. A larval performance index, measured on simulated cactus rots at low, moderate and high densities in single-species cultures, and at moderate and high densities in mixed-species cultures, was used to compare the relative intensity of intra- and interspecific competition at the same total larval density per 5 g necrotic cactus. Larval performance of both fly species was greatest on O. streptacantha, intermediate on O. tomentosa, and least on O. stricta in both single-species and mixed-species cultures. On O. stricta, the performances of D. aldrichi and D. buzzatii were not different when in single-species cultures, but that of D. aldrichi decreased significantly in mixed-species cultures. On the other two cactus species, the performances of D. aldrichi and D. buzzattii were not different in mixed-species cultures. The order of preferences by adult females for the cacti differed from that for larval performance, with females of both species prefering O. stricta. Analysis of microbial numbers growing on the cacti showed little difference among cacti at the rot age used for testing adult preference, but later growth was greater on O. tomentosa and O. streptacantha, the cacti that best supported larvae. Differential larval performance on O. stricta may contribute to the rare presence of D. aldrichi in the southern part of the cactus distribution, while the superior quality of O. tomentosa and O. streptacantha (larger rot size and higher microbial concentration) may reduce competition and facilitate cocxistence of the fly species in the north.     

A survey of running crab spiders (Araneae: Philodromidae) in Iran

Nine species and four genera of Philodromidae are identified and recorded from various parts of Iran including Pulchellodromus medius (O. Pickard-Cambridge, 1872) (genus and species new to Iran) and Thanatus setiger (O. Pickard-Cambridge, 1872) (new to Iran). The male of Rhysodromus hierosolymitanus (Levy, 1977), which was previously known only from females, is described and diagnosed here.     

Wolbachia infection and an all-female trait in Ostrinia orientalis and Ostrinia zaguliaevi

Sex ratio distortion toward females (SR trait), induced by a Wolbachia bacterium, has been reported in two species of the Ostrinia furnacalis group, viz., O. furnacalis, and O. scapulalis (Lepidoptera: Crambidae). In addition, an SR trait caused by abacterial, unidentified agent(s) is known in O. scapulalis. Here we examined the SR trait in four other species of the furnacalis group, viz., O. orientalis, O. zaguliaevi, and O. zealis from Japan, and O. nubilalis from central and eastern Europe. Wolbachia infection was detected in three O. orientalis females and in one O. zaguliaevi female, and the infection was always associated with the SR trait. In terms of wsp and ftsZ gene sequences, Wolbachia strains in O. orientalis and O. zaguliaevi were indistinguishable from each other, or from those in O. furnacalis and O. scapulalis. These findings suggest that Wolbachia strains in the four Ostrinia species are probably identical. In addition, one O. zealis female, which was negative in diagnostic PCRs for Wolbachia and general bacteria, produced an all‐female brood. This trait was very similar to the SR trait caused by abacterial agent(s) in O. scapulalis.     

Copepods of the Genus Oithona Baird, 1843 from mangrove areas of Central and South America

The distribution of the cyclopoid Genus Oithona in waters bordered by mangroves along the coast of Central and South America was studied. Of the ten species previously registered only O. hebes Giesbrecht, O. oswaldocruzi Oliveira, O. alvarezi Lindberg and O. fonsecae Ferrari & Bowman remain valid. O. hebes and O. oswaldocruzi are redescribed and their synonymies extensively discussed. No representatives of O. alvarezi and O. fonsecae were examined.Integumental pore signature patterns of oithonid females are described for the first time. The importance of the pore signature of the cephalosomic flaps of the males as a taxonomic character is discussed.     

Geographic variability in diapause response of Japanese Orius species

Interspecific and latitudinal variation in diapause characteristics were examined in 12 strains of Orius species (Heteroptera: Anthocoridae) including O. sauteri (Poppius), O. nagaii Yasunaga, O. minutus (L.), O. strigicollis (Poppius), and O. tantillus (Motschulsky) from Japan. A latitudinal cline was found in the photoperiodic response controlling reproductive diapause: the lower the latitude, the lower the diapause incidence and the shorter the critical daylength. To examine the overwintering success, eight strains including four species derived from different latitudes (26–43° N) were reared outdoors in Tsukuba (36° N), central Japan from the autumn of 1998 to the summer of 1999, and their winter survival and spring fecundity were recorded. Most females of the northern strains entered diapause in the autumn when the temperature was still high, and died before winter without oviposition. In the southern strains including a nondiapause Okinawa (26° N) strain of O. strigicollis, females overwintered as well as native strains in a state of quiescence. In all strains, the winter survival was significantly lower in males than in females, and eggs and nymphs failed to overwinter.     

Cytogenetic variability in genus odontocheila (Coleoptera,Cicindelidae): karyotypes,C-banding,NORs and localisation of ribosomal genes of O. confusa and O. nodicornis

Two species of Odontocheila, O. confusa and O. nodicornis, from the Neotropical Region were studied regarding their karyotypes, localisation and activity of ribosomal genes and C-banding. The species, although belonging to the same genus, have quite distinct karyotypes. O. confusa has 10 pairs of autosomes and a single sex chromosome mechanism of the XY/XX type, thus a diploid value of 2n = 22 in males and females. One aneuploid male with a diploid number of 2n = 20 and one male with three B chromosomes were found in a total of eight males studied. O. nodicornis has 17 autosomal pairs and also a single chromosome system but of the X0/XX type, thus a diploid value of 2n = 35 in males and 2n = 36 in females. Fluorescence in situ hybridisation (FISH) revealed the presence of rDNA clusters in two autosomes in both species in mitotic and meiotic figures. Silver staining of male interphase nuclei confirmed the FISH results and showed that all rDNA genes were active. C-banding analysis revealed the presence of constitutive heterochromatin in the centromeres of all chromosomes in the two species plus two pairs in O. nodicornis with terminal positive C-bands. These results are discussed from the cytogenetic and evolutionary point of view.     

To change or not to change sex: A comparison between twoOphryotrocha species (Polychaeta)

Summary The polychaeteOphryotrocha puerilis is a male-to-female sex-changer, whereasO. labronica has separate sexes throughout life. In other respects the two species are remarkably similar: they occur in the same habitat, they look the same, they eat the same things, and in someO. labronica populations sex-changers can actually be found. The size-advantage hypothesis predicts that inO. puerilis males should not benefit reproductively from a size increase as much as males inO. labronica: henceO. puerilis but notO. labronica males should change to the female sex at a certain size. I experimentally compared reproductive success at different body sizes between the two species. In isolated male-female pairs reproductive rate increased significantly with female body size but not with male body size, and this pattern was the same in both species. Hence male fecundityper se cannot account for the difference in reproductive type between the two species. In other experiments I investigated if larger males gained access to more females because they were superior competitors for mates or were preferred by females, compared to small males. InO. puerilis the combined effect of these two factors conferred no size advantage to the males, whereas inO. labronica larger males acquired more females than did smaller males. Hence interactions among males and females, in accordance with the size-advantage hypothesis, can explain why sex change is maintained inO. puerilis, and why separate sexes are maintained inO. labronica.     

Cephalic modifications in dimorphic dwarf spiders of the genus oedothorax (Erigoninae,Linyphiidae, Araneae) and their evolutionary implications

Reproductive competition among males selects for a broad variety of strategies and traits from mate guarding to nuptial food gifts. Males of many dwarf spider species possess conspicuous secondary cephalic modifications, and the few studies available suggest that these cephalic structures are connected to extensive glandular tissue. Because females were observed to contact the male head structures during mating, these traits may have evolved in the context of sexual selection. We investigated the structure, glandular equipment, and sensory equipment of the cephalic regions of several species of the dwarf spider genus Oedothorax with varying degrees of sexual dimorphism using light and electron microscopy. In one Oedothorax species, there are two male morphs that exhibit a cephalic modification (O. gibbosus gibbosus) or not (O. gibbosus tuberosus). Our study demonstrates that all males investigated produce cephalic secretions, irrespective of the morphology of their cephalic region, however, they may differ in amount of secretion and in cellular organization. In males of O. apicatus, O. gibbosus gibbosus and O. retusus the gland cells are very abundant in the area of a cephalic hump, whereas in the less conspicuous O. agrestis, and O. gibbosus tuberosus the gland cells are restricted to a small area behind the ocular region or include the ocular region as in O. fuscus. The glandular tissue consists of two gland types in O. agrestis, O. fuscus, O. gibbosus tuberosus and O. retusus and of only one type in O. apicatus and O. gibbosus gibbosus. The setae present on the head structure of all species seem to function as mechano‐ and/or chemoreceptors. The implications of our findings for the evolution of secretory head structures are discussed along with their potential for driving speciation. J. Morphol. 2011. © 2011Wiley‐Liss, Inc.     

Competitive advantage of the invasive copepod Oithona davisae over the indigenous copepod Oithona nana in the Marmara Sea and Golden Horn Estuary

Around 2010, the alien copepod Oithona davisae was introduced to the Marmara Sea and Golden Horn Estuary to live alongside the native species, Oithona nana. By October 2015, the population number, including nauplii, of the introduced species (213,600 ind m^?3) was higher than that of the native species (54,900 ind m^?3) and close to that of O. davisae in Sevastopol Bay of the Black Sea (342,000 ind m^?3) where it appeared 14 years ago. A high percentage of O. davisae females with ovisacs (up to 30% of total female number) carrying up to 15.1 ± 2.1 eggs in the sac and the predominance of nauplii in the population (up to 95% of the total population number) indicate that this alien copepod has become a permanent component of the Marmara Sea and Golden Horn Estuary ecosystem. Our experiments showed that in comparison with widely euryhaline O. davisae, O. nana is a stenohaline species. It has a salinity tolerance in the range of 13–27 psu and, in spite of having a larger body, a lower body density (1.037 ± 0.007 g cm^?3) and sinking speed. Carbon-specific respiration rates of both species were close (0.32–0.38 μL O₂ μgC^?1 day^?1) and similar to that of O. davisae from the Black Sea during this period but the frequency and speed of routine jumps, and the maximum escape reaction speed (up to 23.3 ± 1.7 cm s^?1) in O. davisae from the Marmara Sea were significantly higher. This indicates the higher adaptive potential of O. davisae in this situation compared to that of O. nana.     

Influence of thrips prey species on the life-history and behaviour of Orius albidipennis

The effects of two diets, i.e., cowpea leaves plus Megalurothrips sjostedti larvae versus cowpea leaves alone, on nymphal development and mortality of Orius albidipennis were studied under controlled laboratory conditions in Benin, West Africa. Nymphal development was longer when O. albidipennis was fed with cowpea leaves only, compared to the diet complemented with M. sjostedti larvae (17.6 days versus 14.8, respectively). Nymphal mortality was very high (78.6%) if fed with cowpea leaves only, and still relatively high if the diet was complemented with thrips larvae (44.4%).In a separate study on the longevity and fecundity of O. albidipennis adult females feeding on M. sjostedtilarvae, an average of 6.8 eggs per day (maximum 16 eggs) and a mean total fecundity of 61.1 eggs were observed. The females lived on average 13.5 days.Finally, observations on the predation by O. albidipennis adults on three different thrips species revealed that M. sjostedti larvae were killed at a lower rate than larvae of Ceratothripoides cameroni and Frankliniella schultzei. Higher predation rates were measured using unmated females and males than in mated females. However, the rate of first attack, measured as first larva attacked in dual-choice assays, was higher for M. sjostedti when a F. schultzei larva was offered simultaneously, and not different when a C. cameroni or Sericothrips adolfifridericilarva was offered.The results of this study are discussed with regard to the lack of efficacy of O. albidipennis as biological control agent for M. sjostedti.     

Rearing phonotactic parasitoid flies [Diptera: Tachinidae,ormiini, ormia spp.]

Females of ormiine tachinids fly to their hosts' calling songs and deposit larvae on the host or nearby. Two species,Ormia ochracea (Bigot) andO. depleta (Wiedemann), were reared for at least 8 generations, making them the first ormiines to be laboratory-propagated. Both were reared on natural hosts:Gryllus spp. field crickets (principallyG. rubens) forO. ochracea, andScapteriscus spp. mole crickets forO. depleta. Commercially rearedAcheta domesticus tested as hosts were less satisfactory. Hosts were parasitized manually or by confinement with flies or planidia (infective larvae). Transparent, cylindrical, sleeved cages were designed to accommodate parasitized hosts and pupae and adults ofO. ochracea. Cages were joined to allowO. ochracea to cycle through its stages with minimum handling and care. Parasitized hosts and pupae ofO. depleta were held in containers of damp sand; adults were held in cages developed forO. ochracea. Adults of both species were maintained on applesauce, sugar cubes, powdered milk, and water. The life cycle ofO. ochracea was about 31 days and ofO. depleta about 36 days, with the principal difference being the time required for planidia to complete development. InO. ochracea the adults emerged synchronously but inO. depleta males preceded females. In both species sex ratio was generally I: 1 and females lived slightly longer than males.O. depleta from our laboratory colony have been released for biological control of mole crickets.      

Comparative morphology of Ostertagia mossi and Ostertagia dikmansi (trichostrongylidae) from Odocoileus virginianus and comments on other Ostertagia spp. from the Cervidae

The synlophes of Ostertagia mossi Dikmans, 1931 and O. dikmansi Becklund & Walker, 1968 were found to be identical supporting recognition of these as the major and minor morphotypes, respectively, of a putative species pair within the Ostertagiinae. The cervical synlophe included three narrowly spaced, continuous, parallel ridges laterally and three parallel but more widely spaced ridges in the dorsal and ventral fields (Type II and Type A patterns, respectively). The disposition of the synlophe in conjunction with a long oesophageo-intestinal valve, and attributes of the genital cone and spicules are characteristics shared among other Ostertagia spp. from cervids in the Holarctic region that allow recognition of a species group morphologically distinct from the Ostertagiinae of domestic ruminants. The morphological similarity of O. mossi/O. dikmansi, O. leptospicularis Assadov, 1953/O. kolchida Popova, 1937 and O. gruehneri Skrjabin, 1929/O. arctica Mitzkewitsch, 1929 is substantial, but these species can be differentiated by small but constant differences in the synlophe and genital complex of males; females cannot be easily distinguished. The morphological similarity of this cryptic complex of species and their relatively restricted distribution among cervids suggests a coevolutionary history for hosts and parasites in the Holarctic region.     

Assessing the taxonomic status of Osmoderma cristinae (Coleoptera: Scarabaeidae), endemic to Sicily,by genetic,morphological and pheromonal analyses

Resolving complexes of closely related and cryptic insect species can be challenging, especially when dealing with rare and protected taxa that are difficult to collect for genetic and morphological analyses. Until recently, populations of the genus Osmoderma (Scarabaeidae), widespread in Europe, were treated as a single species O. eremita (Scopoli, 1763) in spite of observed geographic variation in morphology. A previous survey using sequence data from the mtDNA cytochrome C oxidase I gene (COI) revealed the occurrence of at least two distinct lineages within this species complex: O. eremita in the west and O. barnabita Motschulsky, 1845, in the east. Interestingly, beetles confined to Sicily have been described as a distinct species, O. cristinae Sparacio, 1994, based on morphological traits. Only few Sicilian specimens were included in the former genetic analysis, and the results led to a still questionable taxonomic rank for these populations. To explore the robustness of the previous taxonomic arrangement for O. cristinae, a combination of genetic, morphological and pheromonal analyses was used. A 617‐bp fragment of the COI gene, aligned with O. cristinae and O. eremita sequences already available in GenBank, showed a clear genetic divergence between the two species (interspecific mean distance = 6.6%). Moreover, results from AFLP markers sustained the distinction of the two species. In addition, geometric morphometric analyses of the shape of male genitalia revealed a clear differentiation between the two species. Via scent analysis and field trapping, we demonstrated the production of the sex pheromone (R)‐(+)‐γ‐decalactone by males of O. cristinae, the attraction by conspecific individuals (mostly females) to this compound, and a lack of antagonistic effect of (S)‐(–)‐γ‐decalactone. The fact that O. eremita and O. eremita use the same compound for mate finding suggests that this sex pheromone has not undergone a differentiation and probably the allopatry of these two species compensates for the absence of a mechanism to avoid cross‐attraction. Our genetic and morphological data support the divergence of the two species and confirm the species status for O. cristinae, while sex pheromones are confirmed to be invariant among different species of the genus Osmoderma.