Research Article |
Corresponding author: Dmitry A. Gapon ( tentatdag@gmail.com ) Corresponding author: Valentina G. Kuznetsova ( valentina_kuznetsova@yahoo.com ) Academic editor: Snejana Grozeva
© 2021 Dmitry A. Gapon, Valentina G. Kuznetsova, Anna Maryańska-Nadachowska.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Gapon DA, Kuznetsova VG, Maryańska-Nadachowska A (2021) A new species of the genus Rhaphidosoma Amyot et Serville, 1843 (Heteroptera, Reduviidae), with data on its chromosome complement. Comparative Cytogenetics 15(4): 467-505. https://doi.org/10.3897/CompCytogen.v15.i4.78718
|
A new species, Rhaphidosoma paganicum sp. nov. (Heteroptera: Reduviidae: Harpactorinae: Rhaphidosomatini), is described from the Dry Zone of Myanmar. It is the fifth species of Rhaphidosoma Amyot et Serville, 1843, known from the Oriental Region, and the first record of the genus for Myanmar and Indochina. The structure of the external and internal terminalia of the male and female is described and illustrated in detail. The completely inflated endosoma is described for the first time in reduviids. The complex structure of the ductus seminis is shown; it terminates with a voluminous seminal chamber which opens with a wide secondary gonopore and may be a place where spermatophores are formed. The new species is compared with all congeners from the Oriental Region and Western Asia. It is characterised by the absence of distinct tubercles on the abdominal tergites of the male, the presence only two long tubercles and small rounded ones on the abdominal tergites VII and VI, respectively, in the female, the presence of short fore wing vestiges which are completely hidden under longer fore wing vestiges, and other characters. In addition to the morphological description, an account is given of the male karyotype and the structure of testes of Rh. paganicum sp. nov. and another species of Harpactorinae, Polididus armatissimus Stål, 1859 (tribe Harpactorini). It was found that Rh. paganicum sp. nov. has a karyotype comprising 12 pairs of autosomes and a multiple sex chromosome system (2n♂=24A+X1X2X3Y), whereas P. armatissimus has a karyotype comprising five pairs of autosomes and a simple sex chromosome system (2n♂=10A+XY). The males of these species were found to have seven and nine follicles per testis, respectively. FISH mapping of 18S ribosomal DNA (major rDNA) revealed hybridisation signals on two of the four sex chromosomes (Y and one of the Xs) in Rh. paganicum sp. nov. and on the largest pair of autosomes in P. armatissimus. The presence of the canonical “insect” (TTAGG)n telomeric repeat was detected in the chromosomes of both species. This is the first application of FISH in the tribe Raphidosomatini and in the genus Polididus Stål, 1858.
18S rDNA, completely inflated aedeagus, FISH, karyotype, male and female genitalia, morphology, Myanmar, new species, Oriental Region, Reduviidae, Rhaphidosoma, taxonomy, testes, (TTAGG)n
Harpactorinae are the largest subfamily of Reduviidae, comprising approximately 2,330 species and 320 genera in its worldwide distribution (
The genus Rhaphidosoma includes about 50 species distributed mainly in the Afrotropical Region. Twelve species are known in the Palaearctic, namely in North Africa and Western Asia, and only three species have so far been known in the Indian and Ceylonese subregions of the Oriental Region. In this article, a new species from the Indo-Chinese Subregion is described. As far as is known, species of this genus live in deserts and savannas in grass or low bushes (
To clarify the circumscription and status of the tribe Rhaphidosomatini, a detailed examination of the morphology of the listed taxa, with the involvement of new characters, including karyological ones, is necessary, and this work is a small step towards this goal. In particular, the completely inflated endosoma of a new Rhaphidosoma species, which has a complex structure and is rich in characters significant for taxonomy, is described for the first time for reduviids, and the structure of the female internal genitalia is also examined.
Our work was aimed also to describe the karyotype of a new species of Rhaphidosoma and search for the molecular composition of telomeres and localisation of 45S rDNA loci in chromosomes of this species and another harpactorine species, Polididus armatissimus Stål, 1859 (tribe Harpactorini), distributed in the Oriental and eastern Palaearctic regions. The standard karyotype of P. armatissimus was first studied by
Previous original papers and revisions reported the chromosome complements of approximately 80 species (3% of the described ones) in about 40 genera (10% of the recognised ones) of Harpactorinae (
In recent years, knowledge of true bug cytogenetics has advanced significantly due to the use of modern techniques and approaches including chromosomal bandings, FISH, GISH, DNA content analysis, etc. (see for review
The subfamily Harpactorinae is much less studied regarding chromosomal distribution of rDNA. Currently, data are available only for seven species in six genera (of the 2330 species described and 320 genera recognised;
According to various authors, the tribe Rhaphidosomatini includes five (
The material for this study was collected by the first author during his expedition to Myanmar. The detailed data on the locality and the quantity of the material is provided in the section “Results and Discussion”: in the description of the new species (for Rhaphidosoma paganicum sp. nov.) and in the section “Chromosomal analysis” (for Polididus armatissimus).
Morphological studies. The male and female terminalia were examined in wet preparations; the aedeagus was also examined in an entirely inflated condition in dry preparations made using the method of inflation by means of glass microcapillaries (
The terminology for male genitalia partly follows
All measurements are given in millimetres.
The holotype and paratypes of the new species are stored at the Zoological Institute of the Russian Academy of Sciences, St Petersburg, Russia (
Chromosome studies. One male of the new species and eight males of Polididus armatissimus were studied using conventional chromosome staining and FISH with 18S rDNA and (TTAGG)n probes.
Fixation and slide preparation. Whole individuals were fixed immediately after collecting in 3:1 (ethanol: acetic acid) fixative. Chromosome preparations were made from the male gonads. The testes were extracted from the abdomen; testicular follicles were separated from each other in order to determine their number and shape, placed on a slide in a drop of 45% acetic acid, covered with a coverslip, and squashed by gently pressing it. No more than one or two follicles were placed on each slide. The coverslip was removed with a razor blade after freezing with dry ice, and the slide was then dehydrated in fresh fixative (3:1) and air dried.
Routine staining. For this staining, we followed the Schiff-Giemsa method (
Fluorescence in situ hybridisation (FISH). Probes for 18S rDNA and (TTAGG)n were prepared and two-colour FISH was carried out as described by
Microscopy and imaging. The routinely stained preparations were analysed using an Olympus BX 51 light microscope with an Olympus C-35 AD-4 camera. FISH images were taken using a Leica DM 6000 B microscope with a 100×objective, Leica DFC 345 FX camera, and Leica Application Suite 3.7 software with an Image Overlay module (Leica Microsystems, Wetzlar, Germany). The filter sets applied were A, L5 and N21 (Leica Microsystems). The specimens, from which the chromosome preparations have been obtained, are stored at the Zoological Institute RAS (St Petersburg, Russia).
Tribe Rhaphidosomatini
Holotype. Male (glued to rectangular piece of card), Myanmar, Mandalay Region, nr Nyaung-U Town, 21°10'47.2"N, 94°53'37.9"E, 31.X.2019, D.A. Gapon leg. (
Paratypes. Same data as for holotype, 5 males, 1 female mounted as holotype, 3 males in ethanol, 1 male in fixative, with a series of karyological preparations on slides (
Body strongly elongated, rod-shaped, with subparallel lateral margins, slightly widened at level of thoracic segments. Antennae and legs long and thin. Both sexes with vestigial fore and hind wings.
Colouration and integument. Body dark reddish-brown, often with blackish sides; ventral surface of abdomen with a more or less distinct median yellowish stripe; tarsi and last two segments of antennae yellowish brown; claws and apex of last segment of rostrum black. Body entirely, except for last two segments of rostrum, covered with dense, adpressed, whitish scale-like setae; they rather long on head, slightly shorter on thorax and abdomen, and very short and sparse on antennae and legs. On abdomen of female, they are shorter than on that of male, therefore looking less dense. Head ventrobasally with very long and dense erect setae; similar long setae, directed anteriorly, located at anterior angles of pronotum; thoracic sternites in their anterior and posterior parts near coxal cavities with dense, rather long, raised setae.
Some setae all over body, including legs and antennae, semierect, located on sparse, rounded, minute setiferous tubercles, those being visible only on wet preparations and hidden by setae on dry specimens. Such tubercles on dorsal and lateral surfaces of postocular part of head larger (looking like granules on dry specimens), bearing relatively long setae. Semierect setae on preocular part of head slightly shorter, becoming longer and denser on dorsal surface of clypeus; several longer setae located laterally anterior to eyes and on antennal tubercles. Ventral surfaces of head and thorax with less long semierect setae, dorsal surface of thorax and whole abdomen with short semierect setae; first segment of each antenna in basal part with semierect setae slightly shorter than thickness of the segment and increasing in length towards its apex; second segment with setae not exceeding its thickness and also with sparse, longer setae; third and fourth segments with very short, semierect setae. Semierect setae on coxae, trochanters and femora rather short, longer, denser on tibiae and becoming longer towards apices of tibia.
V-shaped spot on dorsal surface of preocular part of head, longitudinal stripes on sides of ventral surface of head, a thin medial stripe on ventral surface of abdomen, lateral irregular stripes and extreme margins of abdominal ventrites with very sparse, almost absent pubescence. Rostrum shining, with sparse, very short, semierect setae, only its first visible segment with adpressed pubescence and several longer, semierect setae. Small, round, dark, shining, slightly depressed scarlike marks located in pairs on abdominal tergites: approximately in middle of combined tergites I–III and before middle of each subsequent tergite; the same markings, longitudinal anterior and rounded posterior, located at anterior angle of each abdominal ventrite.
Simple scale-like setae and cuticle between them covered with a white waxy coating, that being especially abundant and thick on ventral surface of body.
Head
(Figs
Rhaphidosoma paganicum sp. nov., holotype in dorsal view A head and prothorax B meso- and metathorax C abdomen. Scale bars: 1 mm.
Rhaphidosoma paganicum sp. nov. A anterior part of body in ventral view B anterior part of body in right lateral view (right fore and middle legs omitted) C extreme apex of fore leg in anterior view. Holotype (A) and paratype (B, C). Scale bars: 1 mm.
Thorax
(Figs
Rhaphidosoma paganicum sp. nov., metanotum in left dorsolateral view at a wet preparation, under high magnification. Vestige of the left forewing is removed. Red arrow indicates a vestige of the hind wing, and blue arrows, lateral carina of the metanotum.
Labial sulcus wedge-shaped, tapering posteriorly, with thinnest transverse stridulation ribs, bounded by rounded keels, tapering and converging posteriorly. Coxal cavities located near anterior margin of prothorax, closed posteriorly and open anteriorly, separated from each other by a very narrow, sharp carina. Fore coxae contiguous. Each coxal cavity posteriorly with rather large, rounded fossa, corresponding to large internal hook-shaped apodeme lying in transverse plane, having flattened apex directed medially and ventrally.
Mesothorax wider than prothorax, trapezoidal, its pleural areas wide, with margins converging anteriorly in dorsal view. Mesonotum narrower than pronotum, its lateral margins almost parallel, slightly convex in middle, slightly concave anteriorly and posteriorly. Disc slightly convex, without a distinct medial sulcus or carina, laterally bounded along its entire length by a pair of wide flattened carinae, those being strongly smoothed anteriorly and passing into vestiges of fore wings posteriorly. The latter narrow, elongate-triangular, incumbent on metanotum, reaching its posterior margin, slightly curved medially before pointed apices. Scutellum distinct, slightly shorter than its width, convex, fused with mesonotum without distinct suture, with sharp apex and posterior margin bordered by rounded carina thickening towards middle. Small, rounded spiracle located under convex posterior margin of epimeron near dorsal margin of pleurite.
Middle coxal cavities open anteriorly, separated each from other by wider than in prosternum, flat, raised carina. Middle coxae slightly more widely spaced than anterior ones.
Metathorax short, slightly wider than mesothorax, its pleural areas wide in dorsal view, with lateral margins subparallel in anterior part and diverging posteriorly in posterior part. Metanotum slightly wider than mesonotum; its disc rather convex, without a medial sulcus or carina, laterally bounded by lateral carinae. They narrow, subparallel, hidden by vestiges of fore wings in anterior half and, in posterior half, wide, flat, tapering towards posterior ends, reaching posterior margin of metathorax and diverging. Base of each hind wing vestige looking like a narrow longitudinal carina, medially adjacent to anterior half of each lateral carina of metanotum (Fig.
Hind coxal cavities closed anteriorly, open posteriorly. Hind coxae wider moved apart than middle ones. Space between middle and hind coxal cavities monolithic, rhomboid, elongated posteriorly, with almost flat, barely depressed surface and thin medial sulcus. Ostiole of metathoracic scent gland and evaporatorium absent. Epimeron shaped as large, triangular, convex plate with rounded posterior margin.
Note. It seems that in the description of some species of Rhaphidosoma, posterior ends of lateral carinae of the mesonotum are confused with vestiges of the hind wings, which are actually absent in these species. Genuine vestiges of the fore and hind wings are described in this article, and the representation of this character in the genus requires clarification.
Legs. Coxae of all legs longitudinal, swollen; femora and tibiae evenly slender, without any denticles. Anteromedial surface of each fore tibiae subapically with distinct comb (Fig.
Abdomen
(Figs
Rhaphidosoma paganicum sp. nov. A boundary between tergites IV and V, and opening of abdominal scent gland in male (paratype) B boundary between tergites V and VI in male (paratype) C boundary between tergites VI and VII in male (paratype) D apex of abdomen of male (paratype) in right lateral view E abdomen of female in dorsal view F apex of abdomen of female in right dorsolateral view. Wet preparations (A–C) and dry specimens (D–F). Red arrows indicate small tubercles on the posterior margin of tergite VI in female. Scale bars: 1 mm.
Ventrites rather strongly convex; boundaries between ventrites II and III on inner side with two slightly spaced, concave, transverse cristae having a cupped shape, concave anteriorly. Posterior margins of ventrites from II to IV rather deeply concave and less concave in subsequent ventrites.
Connexivum separated dorsally by a rather deep depression. Ventral connexival suture present. Dorsal and ventral laterotergites flat, almost vertical.
Spiracles located on small tubercles. First pair of spiracles located dorsally close to anterior margins of corresponding laterotergites; their tubercles directed slightly posteriad (Fig.
Posterior margin of median tergite VI in male with low, smoothed, transverse medial elevation only with a row of 5–6 setiferous tubercles at posterior margin (Fig.
Tergites in female with three weak longitudinal carinae disappearing anteriorly. Posterior margin of tergite VII medially with two long, digitiform, contiguous throughout tubercles, those being located on rather high common elevation and directed dorsoposteriorly (Figs
Pygophore
(Fig.
Rhaphidosoma paganicum sp. nov., pygophore (A–C) and right paramere (D) at wet preparations (paratype) A left lateral view B ventral view (ventral and lateral branches of basolateral lobes of endosoma are slightly protruding beyond theca under the action of osmotic pressure C dorsal view D right lateral view. Scale bars: 0.5 mm.
Paramere
(Fig.
Aedeagus. Basal plates of phallobase (Fig.
Rhaphidosoma paganicum sp. nov., aedeagus (paratype) at wet preparations A–C theca and phallobase in ventral (A), dorsal (B) and left lateral (C) view D basal foramen of theca in anteriodorsal view (phallobase is strongly unbent anteriad, membrane connecting the basal plates and theca is removed and not shown) E ductus seminis in dissected aedeagus, right lateral view. Abbreviations: b.p – basal plate of phallobase; i.p – inner process of thecal basal foramen; ph.p – phallobasal part of ductus seminis; d.th.p – distal thecal part of ductus seminis; m.th.p – middle thecal part of ductus seminis; p.th.p – proximal thecal part of ductus seminis; s.ch – seminal chamber; v.p – ventral pouch of seminal chamber. Red arrows indicate cords attached to the middle thecal part of ductus seminis. Scale bars: 0.5 mm.
Theca (Fig.
Ventral wall of theca in basal half with two longitudinal, almost rectangular areas of strong sclerotisation, those being separated by rather wide membranous interval. At extreme base, these areas fused with sclerotisation of dorsal wall of theca, extending onto its lateral sides. In middle of theca length, dorsal sclerotisation extending even further to sides and almost touching lateroapical angles of strongly sclerotised parts of ventral wall. Lateral walls of theca in its basal half between described areas of sclerotisation remain membranous. Apical half of ventral wall of theca membranous, with two narrow, highly sclerotised stripes laterally, those being tapering anteriorly and posteriorly. Extreme thecal apex represented by two lobes tapering apically. Dorsal lobe completely sclerotised, with deep, narrow medial notch and external surface striated with dense longitudinal wrinkles. Ventral lobe membranous, trapezoidally rounded apically, with lateral margins reinforced with narrow stripes of strong sclerotisation described above, basally extending under lateral margins of dorsal lobe.
Short unpaired ectodermal vas deferens entering cavity of aedeagus near place of fusion of basal plates (near posterior end of pedicel). Ductus seminis morphologically subdivided into five parts (Fig.
Endosoma (Fig.
Rhaphidosoma paganicum sp. nov., completely inflated aedeagus (paratype) at dry preparations A dorsal view B ventral view C left lateral view D caudal view. Phallobase not shown. Abbreviations: a.t – apical tubercle; a.th – apical margin of theca; d.b – dorsal branch of basolateral lobe; da.t – dorsoapical tubercle; db.l – dorsobasal lobe; db.t – dorsolateral tubercle; dm.l – dorsomesial lobe; dm.s – dorsomesial sclerite; g.l – gonoporal lip; l.b – lateral branch of basolateral lobe; m.b – medial band of the basal part of endosoma; s.g – secondary gonopore; v.b – ventral branch of basolateral lobe. Scale bar: 0.5 mm.
Apical part of endosoma large, obovoid. Its base convex on dorsal side, bearing unpaired dorsobasal lobe and paired dorsobasal tubercles located laterally and slightly more basal than base of the latter. Dorsobasal lobe short, rounded, slightly tapering towards base, directed dorsoanteriorlly. Posterior surface of this lobe with sharply outlined field of microsculpture represented by dense, larger than on basolateral lobes, rather strongly sclerotised, tangentially flattened microspines decreasing towards base of lobe. Apex of lobe with two tiny contiguous tubercles. Dorsobasal tubercles shorter than dorsobasal lobe, tapering broadly to rounded apices directed anterolaterally; surfaces of tubercles without microspines. Distal part of dorsal wall of endosomal apical part smoothly convex, with unpaired dorsomesial lobe, paired dorsomesial sclerites lying on either side of the latter, and with paired membranous dorsoapical tubercles located even more distally. Dorsomesial lobe small, narrowed basally, widening distally, directed dorsoanteriorlly, slightly curved posteriad, without microsculpture. Dorsomesial sclerites rather large, diamond, with rounded angles, posteriorly fused with wall of endosoma, with anterior ends slightly elevated above the wall. Dorsal surface of each sclerite convex, densely and very finely granulated. Dorsoapical tubercles widely spaced, small, conical, with pointed apices directed dorsally, without microsculpture.
Apex of apical part of endosoma broadly dome-shaped, with paired membranous apical tubercles on dorsal side and transverse membranous protuberance on ventral side. Apical tubercles rather large, almost hemispherical, spaced apart. Membranous protuberance crescent, wide, rounded in cross section, rather thick in middle, thinning dorsally towards ends, bordering secondary gonopore ventrally, and here named gonoporal lip. Secondary gonopore looking like a wide gap between gonoporal lip and apex of endosoma, very short in middle, widening laterally; its dorsal margin at each end with a small conical membranous tubercle and very densely covered with finest microsculpture, resulting in it looking dark brown. Ventral half of each apical tubercle, lateral portions of endosomal apex, and entire gonoporal lip densely covered with microspines becoming denser towards middle of the latter.
Ventral wall of apical part of endosoma flat in proximal part and convex distally, with shallow transversal depression behind middle, entirely covered with finest microspines (those being smaller than at apex of endosoma). Distally, this area of microspines somewhat continuing onto lateral walls and, basally on each side, edged by oblique, very weakly sclerotised band.
Notes on functional morphology, dissection and terminology of the aedeagus. In repose, the basal part of endosoma is simply retracted into the theca, while the large apical part is turned inside out like a glove, and when straightened, it should turn back through a relatively small opening at the basal part of endosoma. This mode of folding the endosoma greatly complicates making preparations of completely inflated aedeagi. Perhaps for that reason and because of the high water pressure required in this case, the only completely inflated preparation that the first author (D.G.) obtained well, burst in two places, on the dorsal ends of the gonoporal lip, and these places were reconstructed in the drawings. It should also be noted that all the microspines in the drawings are shown slightly larger than they are, since D.G. did not have the technical ability to draw them very thin.
Perhaps the sclerotised medial band of the basal part of endosoma corresponds to the merged “struts” of some other reduviids, although D.G. does not quite comprehend what “struts” are as described by
It is hard not to associate the complex structure of the ductus seminis, the extreme distal part of which is represented by the extensive seminal chamber with the large pouch and opens by the wide secondary gonopore possessing soft margins, with the presence of spermatophores in insemination in reduviids (about this see e.g.
Female external terminalia
(Fig.
Rhaphidosoma paganicum sp. nov., details of the structure of female abdomen, at wet preparations A apical part of abdomen in left dorsolateral view B boundary between tergites VI and VII under high magnification C extreme apex of abdomen in ventral view D terminalia in ventral view (right gonocoxite I is removed) E right gonocoxite I. Abbreviations: ga.I – gonapophyse I; ga.II – gonapophyse II; gc.I – gonocoxite I; gc.II – gonocoxite II; gp – gonoplacs; pt.VIII – ventral paratergite VIII; s.r – second ramus; t.VIII – tergite VIII; t.IX – tergite IX. Scale bars: 1 mm.
Gynatrium
(bursa copulatrix) (Fig.
Rhaphidosoma paganicum sp. nov., gynatrium in dorsal view, at a wet preparation. Abbreviations: a.b – anterior band of gonapophyse I; a.p – anterior pouch of gynatrial cone; g.c – gynatrial cone; gc.II – gonocoxite II; l.f – lateral fold of dorsal wall of gynatrium; l.o – lateral ectodermal oviduct; m.f – median fold of dorsal wall of gynatrium; m.o – medial oviduct; pr – proctiger; ps – supposed duct of pseudospermatheca; s – sclerite of semicircular fold (contour of the left sclerite is outlined with a red line); s.f – semicircular fold of dorsal wall of gynatrium. Red dotted line outlines the ring sclerite. Scale bar: 1 mm.
Measurements (males / female). Body length 19.04–19.89 / 20.23; length of head 3.55–3.78 / 3.58; length of head anterior to transverse sulcus 1.93–2.05 / 2.03; length of head posterior to transverse sulcus 1.73–1.63 / 1.55; width across eyes 0.91–0.95 / 0.93; synthlipsis 0.50–0.53 / 0.50; length of prothorax at midline 1.48–1.70 / 1.58; width of prothorax 1.23–1.30 / 1.28; length of mesothorax 1.28–1.56 / 1.45; width of mesothorax 1.43–1.53 / 1.50; length of metathorax 0.43–0.50 / 0.43; width of metathorax 1.50–1.63 / 1.63; width of abdomen at level of first spiracles 1.13–1.25 / 1.30; length of abdomen 13.40–14.50 / 14.70; length of first antennal segment 6.15–6.50 / 5.50; length of second antennal segment 3.45–3.60 / 3.20; length of third antennal segment 2.55–2.90 / 2.25; length of fourth antennal segment 2.15; total length of labium 3.73–3.93 / 3.75; length of second visible labial segment 2.78–2.98 / 2.78; length of third visible labial segment 0.50–0.55 / 0.53; length of fore coxa 0.78–0.85 / 0.78; length of fore femur 6.70–7.10 / 6.30; length of fore tibia 8.80–9.10 / 8.10; length of middle coxa 0.70–0.78 / 0.73; length of middle femur 5.40–5.90 / 5.70; length of middle tibia 6.70–7.20 / 6.50; length of hind coxa 0.83–0.88 / 0.88; length of hind femur 9.70–10.60 / 9.40; length of hind tibia 11.4–12.6 / 11.3.
The species was found within the Dry zone in central Myanmar, whose climate, according to the classification of
The specific name paganicum is a Latin adjective meaning “heathen”; it is given after the type locality that belonged to the Kingdom of Pagan in the XI–XIII centuries AD.
Being predominantly Afrotropical, the genus is represented by only four species in the Oriental Region (Rh. atkinsoni Bergroth, 1893, Rh. tuberculatum Distant, 1904, Rh. greeni Distant, 1906, and Rh. madukaraiensis Ravichandran et Livingstone, 1994). Four species are also known from Western Asia (Rh. argillaceum Horváth, 1929, Rh. bergevini Poppius, 1911, Rh. lutescens Poppius, 1911, and Rh. davatchiae Dispons et Villiers, 1967), and they must be taken into account in comparison with the new species. All these species were described very superficially, more often from one or two specimens of the same sex, and only one of them, Rh. atkinsoni, was recently redescribed in sufficient detail (not counting the male and female terminalia) by
Differences from Rh. argillaceum
[described by
Differences from Rh. bergevini
[described by
Differences from Rh. lutescens
[described by
Differences from Rh. davatchiae
[described by
Distinguished from Rh. atkinsoni
[described based on an unspecified number of specimens (presumably males), redescribed by
Differences from Rh. tuberculatum
[described by
Differences from Rh. greeni
[described by
Differences from Rh. madukaraiensis
[described by
According to the description of Rh. madukaraiensis, it differs from Rh. tuberculatum “by the total absence of thoracic tubercles, cephalic spine and by the obscure development of scutellum, wing pads and mesonotal median carina”. In the specimens of Rh. tuberculatum available to the first author, vestiges of the fore and hind wings are completely absent. The relief triangular structures in the posterior angles of the metanotum, which can be mistaken for vestiges of the hind wings, are in fact lateral carinae. Scutellum of Rh. tuberculatum is very small, much smaller than that of the new species; the mesonotal median carina is absent in both of these species. According to the description of Rh. madukaraiensis, the type series (holotype and several paratypes) consists of males only, but the listed characters of the sculpture of abdominal tergites and the phrase “behind the fifth segment the abdomen abruptly terminates” correspond to the female. The median tergite and paratergites VIII in the female of the new species have rather large triangular prominences on the posterior margins.
Based on the analysis of the only male (paratype) available for such a study, we conclude that the male chromosome complement of the species comprises 12 pairs of autosomes and a multiple sex chromosome system, X1X2X3Y, i.e., n=16(12AA+X1X2X3Y) and 2n=28(24A+X1X2X3Y). The autosomal bivalents make up a decreasing size range; of the four sex chromosomes, Y is the largest, and all three X-chromosomes are approximately the same size (Fig.
Male meiotic chromosomes of Rhaphidosoma paganicum sp. nov., n=12AA+X1X2X3Y (2n=24A+ X1X2X3Y) A first prophase, early condensation stage (chromosomes X1X2X3 are located in a train and the Y is located slightly away from them) B, C metaphase I (sex chromosomes X1X2X3Y are lying side by side inside the ring formed by autosomal bivalents) D hybridisation signals of 18S rDNA-FISH (green) and (TTAGG)n-FISH (red) are visible on Y and one of the X-chromosomes (small green signals are also seen in some autosomal bivalents, but they proved to be not specific), and on both ends of each chromosome, respectively; Inset, Y and an X-chromosome with 18S rDNA signals E (TTAGG)n-FISH-signals are visible in spermatids. Scale bar: 10 μm.
As mentioned in Introduction, the most common karyotype of Harpactorinae includes 2n=28(24A+X1X2X3Y), and Rh. paganicum sp. nov., thus, shares this modality with regard to both the number of autosomes and the sex chromosome system. Previously, there was only one species in the genus Rhaphidosoma with a known (standard) karyotype, Rh. truncatum Jeannel, 1914. According to
Material examined. Thailand, Mae Hong Son Prov., Pai Distr., near Pai Town, 19°21'25.8"N, 98°27'01.0"E, 12,13.XI.2019, at light, D.A. Gapon leg., 8 males (
Based on the analysis of eight males, we conclude that the male chromosome complement of P. armatissimus comprises five pairs of autosomes and a simple sex chromosome system, XY, i.e., n=7(5AA+XY) and 2n=12(10A+XY) as previously noted by
Male meiotic chromosomes of Polididus armatissimus Stål, 1859, n=5AA+XY (2n=10A+XY) A diplotene/diakinesis; heteropycnotic X- and Y-chromosomes form a pseudo-bivalent B, C, D metaphase I/anaphase I transition; X- and Y-chromosomes form a pseudo-bivalent E hybridisation signals of 18S rDNA-FISH (green) and (TTAGG)n-FISH (red) are visible on AAI and on both ends of each chromosome, respectively. Scale bar: 10 μm.
It should be noted that P. armatissimus has the lowest number of autosomes (10A) ever recorded in Harpactorinae. It was previously shown that males of this species originated from Japanese and Indian (Calcutta) populations also have 2n=12(10A+XY), although males from northwest India were reported to have 2n=14(12A+XY) (see for references
Telomeres of both Rh. paganicum sp. nov. and P. armatissimus have clearly demonstrated presence of the TTAGG repeat, which constitutes the first report of the (TTAGG)n telomere motif in the tribe Raphidosomatini and in the genus Polididus (Harpactorini). This so-called “insect” repeat is considered an ancestral DNA motif of insect telomeres (
We found that the genes encoding the major rRNAs were located differently in Rh. paganicum sp. nov. and P. armatissimus. These species have different numbers of autosomes (24A and 10A, respectively) and different sex chromosome systems (X1X2X3Y and XY, respectively); however, there seems to be no correlation between these two characters and the rDNA chromosomal location in Harpactorinae (Table
Chromosomal location of genes for 18S rRNA in karyotypes of nine species of the subfamily Harpactorinae studied to date.
N | Species | 2n | Location of 18S rDNA | Reference |
Tribe Apiomerini | ||||
1 | Apiomerus lanipes (Fabricius, 1803) | 24(22A+XY) | X and Y |
|
Tribe Harpactorini | ||||
2 | Cosmoclopius nigroannulatus (Stål, 1860) | 28(24A+X1X2X3Y) | Y and one of Xs |
|
3 | Montina confusa (Stål, 1859) | 14(12A+XY) | AAI |
|
4 | Polididus armatissimus Stål, 1859 | 12(10A+XY) | AAI | Present paper |
5 | Repipta flavicans (Amyot et Serville, 1843) | 20(18A+XY) | One of sex chromosomes |
|
6 | Rhynocoris iracundus (Poda, 1761) | 28(24A+X1X2X3Y) | Y and one of Xs |
|
7 | Rhynocoris punctiventris (Herrich-Schäffer, 1846) | 28(24A+X1X2X3Y) | Y and one of Xs |
|
8 | Zelus laticornis (Herrich-Schäffer, 1853) | 26(24A+XY) | AAI |
|
Tribe Rhaphidosomatini | ||||
9 | Rhaphidosoma paganicum sp. nov. | 28(24A+X1X2X3Y) | Y and one of Xs | Present paper |
We found that the testes of Rh. paganicum sp. nov. and P. armatissimus males are located laterally at the sides of the alimentary tract, approximately in the middle of the abdominal cavity. The species have seven and nine elongated follicles per testis, respectively. In Rh. paganicum, the follicles have similar length and width; they are arranged side by side being connected by bases. In P. armatissimus, the structure of the testis turned out to be more complex. The follicles are folded three times onto each other and wrapped with a reddish peritoneal sheath. Moreover, they form two groups, one consisting of seven long and wide follicles and the other consisting of two smaller follicles. The same testis structure, although with a different ratio of large and small follicles, is also characteristic of some other species of Reduviidae (
Conception and design of the project, D.G. and V.K.; material collection and description of the new species, D.G.; cytogenetic study, V.K. and A.M-N.; writing the paper, D.G. and V.K.; final approval of the version to be published, all authors.
The work is based on the taxonomic collection of
Dmitry A. Gapon https://orcid.org/0000-0002-4927-9845
Valentina G. Kuznetsova https://orcid.org/0000-0001-8386-5453
Anna Maryanska-Nadachowska https://orcid.org/0000-0003-3270-825X