Antennal Segment Research Articles

A new genus and species of Katiannidae (Collembola: Symphypleona) from Bolivia.

The new genus Borgesminthurinus gen. nov. from Bolivia shares with Sminthurinus the presence of antennal segment IV undivided, antennal segment III with one papilla; sacs of ventral tube smooth; each tenacular rami with 3 teeth and a basal appendix. They also have dens with ventral chaetotaxy reduced and lack mucronal seta; but new genus clearly differs in having thick and barbulate setae on head and body, lacking neosminthuroid setae on abdomen and the presence of seta a0 on Abd. VI acuminate. The new genus differs from Katianna which has divided antennal segment IV, vertex of head with spine-like setae and setae of the body long and smooth.

Morphological Aspects of Antennal Sensilla of the Rhodnius brethesi Matta, 1919 (Hemiptera: Reduviidae) from the Negro River, Amazon Region of Brazil.

Studies conducted in river Ererê located in the left margin of Negro River, municipality of Barcelos, state of Amazonas, have confirmed that Rhodnius brethesi has as its natural habitat the palm tree Leopoldinia piassaba. By scanning electron microscopy, sensillum type was studied on the antennae of R. brethesi. The specimens used come from the field and laboratory colony. No differences were observed between R. brethesi and other Triatominae studied. In the R. brethesi antennas, differences were observed only between the antennal segments and in the dorsal and ventral portions. Trichobothria sensilla show a difference with a lamellar base, suggesting that this conformation of the base of the sensilla is a synapomorphic feature of the genus. Another important observation is that, considering that R. brethesi is a specialist, infesting only one type of palm tree, trichoidea sensilla may be involved with plant-derived odorants. The knowledge of such functions could benefit the understanding of the likely biological role of these structures in chemical communication and also provide basic information for future studies of niche recognition, since this species of triatomine is only found in the L. piassaba palm.

“Surface Ultra-Structural Studies on Antennae in Polymorphs of Weaver Ant Oecophylla smaragdina; Fabricius” (Hymenoptera: Formicidae) with Reference to Sensilla

Oecophylla smaragdina is an established biological pest control agent in south-east Asian continent for cash crops like cashew and mango. It is a cosmopolitan species found all over the Asian continent. Being a social hymenopteran insect, Oecophylla smaragdina has a colony comprising of polymorphs. The morphological and ultra-structural investigation of such polymorphs antenna was done with scanning electron microscopy to reveal presence of various chemosensory, thermo-sensory and tactile sensory sensillae on the antennal segments with their specific role in the polymorphs. The role of worker in foraging activity is supported with the presence of large number of sensilla compared to other castes.

Observations on the Ultrastructure of Antennal Sensilla of Adult Glenea cantor (Cerambycidae: Lamiinae).

The external morphology and distribution of antennal sensilla of Glenea cantor Fabricius were studied with scanning electron microscopy. The antennae of G. cantor were observed to be filiform, consisting of scape, pedicel, and flagellum (nine flagellomeres). Four distinct types of sensory receptors were observed, including sensilla chaetica, sensilla trichodea, sensilla basiconica, and Böhm bristles. Three morphological subtypes of sensilla chaetica were found on the antennae, and sensilla trichodea were also categorized into three morphological subtypes. Sensilla basiconica was grouped into two morphological subtypes that were found on subsegments F2-F9 of the flagellum, and Böhm bristles were only found at the intersegmental joints between the scape and the head and between the scape and the pedicel. The antennae of male and female adults were similar in shape, length, and diameter. However, the length, diameter, distribution, and number of each of the four distinct types of sensilla on the males were significantly different from those on females. The types, lengths, diameters, numbers, and distributions of these sensilla were described, and their possible functions were also discussed. The results indicated that the base and end of an antennal segment have a similar sensillum density, but the middle section sensor density is significantly greater, especially for olfactory and gustatory sensilla, possibly because the joints are more involved in mechanical sensing. The density of sensors is closely related to its sensing function; so, future studies on the biology of olfaction and sexual communication in G. cantor will be facilitated by these observations.

A stereoisomer of JHSB3 with 10S-configuration, 10S-JHSB3, biosynthesized by the corpus allatum of the brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae)

The products released by the corpus allatum (CA), an endocrine gland producing juvenile hormone (JH), were analyzed in three species of stink bugs. Liquid chromatography–mass spectrometry (LC–MS) analysis of the CA products from female adults of Halyomorpha halys (Stal), Nezara viridula (Linnaeus), and Nezara antennata Scott (Hemiptera: Pentatomidae) revealed that the CA biosynthesized JH III skipped bisepoxyside (JHSB3) in all three species. In H. halys, in addition to JHSB3, the CA also produced its stereoisomer, 10S-JHSB3. A bioassay focusing on the number of antennal segments was adopted to examine biological activity of these products. When last instar nymphs were treated with either of the two JHs, they emerged as adults bearing nymphal type antennae with four segments in a dose-dependent fashion, indicating that both JHSB3 and 10S-JHSB3 had the JH activity in H. halys. Therefore, for the first time, 10S-JHSB3 in H. halys was found to be a naturally occurring JH molecule with 10S-configuration.

Antennomere numbers in fireflies (Coleoptera: Lampyridae): unique patterns and tentative explanations

The plesiomorphic antenna with eleven articles is stunningly stable across the over 400.000 beetle species, despite the astonishing diversity of morphologies and ecological settings in which these organisms live. However, a few beetle lineages evolved different antennomere numbers, and these offer an interesting opportunity to understand how an otherwise fixed phenotype may eventually change, and to study what factors shape their patterns of variation. Here, we review for the first time, based on original and literature data, the unique patterns of variation in antennomere numbers in the firefly family (Coleoptera: Lampyridae), which has the greatest range (7–62) in antennomere numbers among beetles despite a relatively low species diversity (∼2000 species). We also tested the hypothesis that antennomere numbers are positively related to body size and explored patterns of antennal asymmetry across Amydetes spp, which have the greatest range in antennomere numbers (24–62). Out of the ∼100 firefly genera, nine show antennomere numbers lower or higher than 11. Among those nine genera with unusual antennomere numbers, five show intraspecific variation as well. In taxa whose antennae have less than 11 antennomeres, males seem to follow mainly light cues to find mates. In Amydetes, we found that antennomere numbers are positively related and negatively allometric to body size, suggesting that in this group the mechanism shaping antennal segmentation is sensitive to body size. Moreover, fluctuating asymmetry was found to be widespread in Amydetes spp., with a difference of up to six antennomeres between left and right antennae. The combined occurrence of unusual antennomere numbers and within-species variation suggests that in several firefly taxa a destabilization of the mechanism driving antennal segmentation has occurred.

A new highly dimorphic genus of Sminthuridae (Collembola: Symphypleona)from Brazil.

A new genus and two new species of Sminthurinae are described. Keratosminthurus tapigu gen. nov. sp. nov. and K. calamitosus sp. nov. show a combination of features that redefines the subfamily Sminthurinae, such as a pair of sminthuroid chaetae, unguis without cavity, nine apical chaetae on tibiotarsus, 11 or more anterior dental chaetae, fourth antennal segment clearly subdivided into many (18 or more) subsegments, and asymmetric apex of mucro. The new genus also presents a striking sexual dimorphism, with modifications on male apical organ of antennal segment III, spines on the clypeus and special organs on the interocular area.

Tryphactothrips rutherfordi (Bagnall) (Thysanoptera, Panchaetothripinae): first description of the male.

The subfamily Panchaetothripinae (family Thripidae) is represented by 140 species under 40 genera (Thrips Wiki 2019). In India, 36 species under 16 genera are recorded (Tyagi Kumar 2016, Tyagi et al. 2017, Rachana and Varatharajan, 2018, Johnson et al. 2019). The members of this subfamily are leaf-feeders and usually dark brown in colour with strongly reticulate sculpture on body, terminal antennal segments needle-shaped, tarsi 1- or 2-segmented, fore wing upper vein fused with costa. The genus Tryphactothrips was established by Bagnall (1919), and this genus remains monobasic with only Dinurothrips rutherfordi Bagnall from Sri Lanka as the type species. The genus Tryphactothrips can be distinguished from related genera by the presence of sculptured round areolae on abdominal segments. It is closely related to Anisopilothrips Stannard Mitri but can be identified by paired sigmoidal setae on abdominal tergites (absent in Anisopilothrips), mesonotum without complete median longitudinal split (complete median longitudinal in Anisopilothrips). Recently, a series of both sexes of Tryphactothrips rutherfordi with banded fore wings was collected on fern from Kerala state of India. Females were identified using published keys (Wilson 1975), and the male is here described for the first time. DNA was isolated from the studied specimens and partial fragment of mtCOI gene was amplified and sequenced (Tyagi et al. 2017). Four sequences were submitted in the GenBank (Accession No. MN627201 to MN627204). Photographs and illustrations were taken through a Leica Trinocular Microscope (Leica DM-1000) using Leica software application suite (LAS EZ 2.1.0). The studied specimens were deposited in the National Zoological Collections (NZC), Zoological Survey of India, Kolkata, India.

A stalk-eyed true bug in mid-Cretaceous Burmese amber (Hemiptera, Pentatomomorpha, Yuripopovinidae)

The extinct family Yuripopovinidae Azar et al., 2011 was erected based on a true bug fossil in Lower Cretaceous amber of central Lebanon. Recently, a unique yuripopovinid Reticulatitergum hui Du et al. (2019), with an areolate body and strongly dilated antennal segment IV, was reported from mid-Cretaceous Kachin amber of northern Myanmar. Herein, the second yuripopovinid genus and species from this amber biota, Caulisoculus electrus gen. et sp. nov., is described and illustrated. The new taxon bears bizarre long eyestalks, which is an unusual morphological trait amongst true bugs. The two specialized yuripopovinid genera (Caulisoculus gen. nov. and Reticulatitergum) suggest that this extinct pentatomomorph lineage was with high disparity in Kachin amber biota.

Generation studies on benthic amphipod-Quadrivisio bengalensis, Stebbing (Gammaridae) from the Kochin Estuary, Southwest coast of India.

Quadrivisio bengalensis (Stebbing Records of Indian Museum, 1, 159-161, 1907), a eurythermal (26.5-32.2 °C) and euryhaline (0.10-26.2 psu) tropical species, makes a profound contribution as a fodder organism to the benthic biomass of tropical backwaters. Studies on life span, variations in broods, fecundity, sex ratio, brooding behaviour, brood stock assessment, growth rate, antennal segments as an index of growth, moulting frequency, mortality and starvation resistance of Q. bengalensis were made for the first time under controlled laboratory conditions of 12-h photo period for 252 days on 8 pairs of specimens (male and female) collected from the field and their successive broods. The life span of females was found to be higher (maximum 220 days) than males (maximum 175 days). Number of broods varied between 5 and 15, depending on the "status of the brood" (early or late). The maximum number of juveniles in a single brood was 24 and that by a single female over the entire life span was 211. The incubation time varied between 6 and 9 days and the duration of moults (8-18 days) was found to increase with the age of the animals. Maximum growth is usually attained by the offspring arising from the 5th to 7th broods. The 4th to 7th broods were the optimal broods for the maximum number of females attaining maturity. For broods 3 to 7 of the parental set, probability of extinction (ξ) calculated on applying stochastic branching process to generation studies for the first time showed an increasing trend with number of broods while a decreasing trend for ξ for 8th and 9th broods, with least ξ for broods 5 to 7 of the 5th, 6th and 7th generations, suggesting life span and fecundity rates as functions of the "brood status" (early or late). Whether it is true with higher crustaceans remains to be explored.

Description of a new species of Pagurus Fabricius, 1775 (Crustacea: Paguroidea: Paguridae) from the Pacific coast of Costa Rica, Central America, with notes on Pagurus albus (Benedict, 1892).

A redescription of Pagurus albus (Benedict, 1892) is presented together with a description of a new species of hermit crab, Pagurus pseudoalbus sp. n., from the Pacific coast of Costa Rica. Pagurus pseudoalbus sp. n. differs from P. albus and P. perlatus by the length of antennal acicles, which do not exceed the distal margin of the 4th antennal segment, whereas in the latter two species, the antennal acicles exceed the 4th antennal segment; the antennular peduncle is proportionally longer than the ocular peduncle in the new species compared to P. perlatus, but shorter than in P. albus; the palm of the right cheliped in P. pseudoalbus sp. n. is 1.3 times as long as broad, while in P. albus and P. perlatus it is 1.0 and 1.4 times as long as broad, respectively. Including the new species, the genus Pagurus in the Eastern Tropical Pacific currently includes 16 species.

A new species of Xenylla Tullberg, 1869 (Collembola: Hypogastruridae)from Peru, with a key to Neotropical species of the genus.

A new species belonging to genus Xenylla Tullberg, 1869 from Peru is described and illustrated. The new species, Xenylla gwiazdowiczi sp. nov., can be distinguished from previously described Xenylla species by combination of the following characters: mucro separated from dens, presence of complete row of setae c on dorsal side of the head, four thick sensilla on antennal segment IV, 19,19,18 setae on tibiotarsi of legs I-III, slightly serrated setae on abdominal segments V-VI, presence of two weakly clavate tenent hairs on each leg. The new species resembles X. spinosissima Najt Rubio, 1978 and X. humicola (Fabricius, 1780). Similarities between them have been discussed. An identification key to Neotropical species of the genus is provided.

The Luciolinae of S. E. Asia and the Australopacific region: a revisionary checklist (Coleoptera: Lampyridae) including description of three new genera and 13 new species.

The Luciolinae of S. E. Asia and the Australopacific region: a revisionary checklist (Coleoptera: Lampyridae) including description of three new genera and 13 new species.

Reduced antennal segmentation in a new species from Iran of the genus Aeolothrips (Thysanoptera: Aeolothripidae).

The number of antennal segments in adults of the different families and genera in the insect order Thysanoptera varies between five and nine. The plesiotypic number is considered to be nine (Zhang et al. 2019), and fossil thrips reported to have 10 to 15 segments (Tong et al. 2019) are generally considered to be aberrations in which the terminal segment bears transverse striae. The 9-segmented condition occurs particularly amongst species that exhibit several other characters in a plesiomorphic state, including all Melanthripidae, two genera of Merothripidae, also most species of Fauriellidae, Stenurothripidae, Heterothripidae, and Aeolothripidae (Mound et al. 1980). Curiously, members of a few genera of Thripidae (Palmer Mound 1985; Minaei 2012) also have nine antennal segments, but this is considered a reversion from the 8-segmented condition that is assumed to be plesiomorphic for that family (Zhang et al. 2019). Variation between eight and nine segments occurs in the genus Anaphothrips, and within that genus a few species exhibit intraspecific variation in antennal segmentation (Mound Masumoto 2009). Intraspecific variation in various characters, including body size, color and wing length, is well documented for the order Thysanoptera (Mound 2005 a, b). However, amongst the 207 listed species of Aeolothripidae there has never been any report of a species bearing antennae with other than nine segments, although these vary in length and shape amongst the different genera. We here describe from Iran a curious species of the genus Aeolothrips that is unusual in having only seven antennal segments, with the number reduced to six or even five in a few individuals in which the terminal segments are fused. These females with 7-segmented antennae were initially considered to be aberrant individuals of some other species. However, 25 females with such antennae have been collected over two years, all from a group of Tamarix trees. Despite extensive studies on the genus Aeolothrips in Iran (Alavi Minaei 2018, 2019), with 30 species now being recorded from this country, no other species has been found with the same colour pattern of the body and fore wings. We therefore conclude that the available specimens represent a valid species in which the antennal segmentation is reduced, and with the terminal segments unstable.

Description of a new species of Willemia (Collembola: Hypogastruridae) from Panama with key to Willemia species occurring in the Americas.

Willemia panamaensis sp. nov. from Panama is described and illustrated. It is characterised by the presence of sensilla I (S2) and i1 (S9) on antennal segment IV, nine vesicles in the postantennal organ, and having dorsal setae and sensilla on abdominal segments V and VI twice as long than on segments I and II. A dichotomous key to species recorded from the Americas is provided. Reference is given to the DNA barcoding sequences of the new species.

A new species of Odontothrips (Thysanoptera, Thripidae) from Fars province, Iran.

Mound and Palmer (1981) included the following eight genera in Megalurothrips genus-group: Ceratothrips, Ceratothripoides, Craspedothrips, Lefroyothrips, Megalurothrips, Odontothripiella, Odontothrips, and Projectothrips. However, a series of shared morphological characters, as well as their shared host-plant association with members of the plant family Fabaceae, indicates that Megalurothrips, Odontothrips, and Odontothripiella are particularly closely related (Xie et al. 2010). The species of thesethree genera all have a pair of dorso-apical setae on the first antennal segment, a character state that distinguishes them from most Thripinae (Zhang et al. 2018). Of these, Odontothrips is the most species-rich genus with 34 speciesdistributed in the Palaearctic (ThripsWiki 2019). In Iran only 5 species (O. confusus, O. iranensis, O. loti, O. meliloti, O. phlomidinus) have been recorded (Minaei 2017). Despite more than 60 years since O. phlomidinus was described from Iran, this species remains known only from the type series (Priesner 1954). In this paper, a new species of the genus is described from southern Iran that seems to be close to O. phlomidinus. Moreover, a provisional key is provided, based on females, for six species recorded from Iran. Authority names are available on the web (ThripsWiki 2019).

Description of a new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) from the redbelly tilapia Coptodon zillii (Gervais) (Perciformes: Cichlidae) in Basrah, southern Iraq

A new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) parasitic on the gills of the redbelly tilapia Coptodon zillii (Gervais) from Basrah, southern Iraq, is described. Dermoergasilus cichlidus n. sp. is morphologically similar to D. longiabdominalis El-Rashidy & Boxshall, 2001 in the body length to width ratio, the swimming legs armature, the shape of the urosome and the small slightly spiniform seta on the exopodal segment of leg 5. However, the main differences are the presence of long setae on the endopod of leg 1 in D. cichlidus n. sp. (vs relatively short setae); the inner apical spine on the tip of the endopod of leg 1 being only slightly longer than the outer apical spine (vs inner apical spine about twice as long as the outer); the first interpodal sternite ornamented with spinules (vs interpodal sternites not ornamented); and the caudal rami and anal somite of equal length (vs caudal rami length c.2/3 of the length of the anal somite). Dermoergasilus occidentalis can be distinguished from D. cichlidus n. sp. by the relative length of the antennal segments, the absence of a minute terminal spine on the digital process of the caudal ramus and by differences in the mouth parts.

Electroantennographic Responses of Aromia bungii (Faldermann, 1835) (Coleoptera, Cerambycidae) to a Range of Volatile Compounds.

Background: The red-necked longhorn beetle, Aromia bungii, is one of the most damaging pests of stone fruit trees. Native to the south-eastern Palearctic and Oriental regions, it invaded and is established to some extent in the Campania Region (Southern Italy). In several cerambycid species, volatile organic compounds (VOCs) have been shown to play a role in mate and host plant location. Methods: The electroantennographic (EAG) technique was employed to explore the antennal chemoreceptivity of male and female A. bungii antennae to 90 VOCs. Results: Increasing EAG amplitudes from the basal to the distal antennal segments were recorded in response to six selected plant volatiles. From the distal flagellomeres, the largest EAG responses (>0.8 mV) were elicited by 2-hexanol, octanal, sulcatone, guaiacol, sulcatol, 2,4-dimethyl-3-hexanol, 2,4-dimethyl-2-hexanone, heptanal, nonanal, (Z)-3-hexenol, and 1-heptanol in both sexes, and by linalool, (E)-2-heptenal, 1-octen-3-ol, (E)-2-octenal, 3-octanol, (E)-2-octen-1-ol, α-phellandrene, and α-terpinene in males. The olfactory system of both sexes proved to be sensitive to changes in stimulus concentration and compound structure. Conclusions: this study demonstrates the capability of A. bungii males and females to detect and discriminate among a wide range of VOCs and provides a basis for further olfactometer and field trapping experiments aimed at identifying behaviorally-active compounds useful for the implementation of semiochemical-based control strategies for this pest.

First record of the genus Eumunida Smith, 1883 (Crustacea, Decapoda, Eumunididae) from the southwestern Atlantic, with the description of a new species

Eumunida picta Smith, 1883, was considered for over a century an amphi-Atlantic species and the only representative of the genus in the Atlantic Ocean, until being split into three species: E. picta sensu stricto (from the northwestern Atlantic), E. bella de Saint Laurent & MacPherson, 1990 and E. squamifera de Saint Laurent & MacPherson, 1990 (from the northeastern and southeastern Atlantic, respectively). Eumunida is now expanded to include a new species, E. notialis, from off the Brazilian coast. Hence, this is the first record of Eumunida and Eumunididae from the southwestern Atlantic. The new species differs from all its Atlantic counterparts in having (1) four hepatic spines; (2) two carapace inframarginal spines; (3) the distal end of the antennal acicle nearly reaching to the articulation between fourth and fifth antennal segments; and (4) the anterolateral spine of the second pleonal tergite obsolete.

A new species of Aethiopella Handschin, 1942 (Collembola, Poduromorpha, Neanuridae) from Neotropical Region, with comments on the genus

Aethiopella Handschin, 1942 as other Pseudachorutinae (Neanuridae) presents a diagnosis with overlapping characters when compared to other similar genera, especially Halachorutes Arlé, 1966, Ceratrimeria Börner, 1906 and Pseudachorutes Tullberg, 1871. This condition, combined to several gaps on the knowledge of described species and a wide range of morphological differences within the genus, reinforces the need of its revision, since it can be an artificial group. In spite of that, a new species, Aethiopella ricardoi sp. nov., is described and illustrated. It resembles the other five Neotropical taxa of Aethiopella but is unique by the combination of fourth antennal segment with trilobed apical bulb and 7 dorsal sensilla, lack of dorsolateral S-microchaeta (ms); postantennal organ with 13-19 vesicles; mandibles with 7-8 teeth; maxillae apically hooked; and tibiotarsi I-III with 19/19/18 chaetae, respectively, with M chaeta slightly basally displaced. We also present an updated diagnosis of Aethiopella based on current knowledge of Pseudachorutinae, a table comparing all species, a key to Neotropical taxa and remarks on the genus.