A Revision of the Genus Argolis (Hemiptera: Reduviidae: Stenopodainae) from Asia

Simple Summary The assassin bug subfamily Stenopodainae is the fifth largest group of Reduviidae, with about 770 valid species known worldwide. Many taxa of Stenopodainae have been poorly studied and are therefore in need of revision. Argolis Stål, 1861 is a medium-sized genus of Stenopodainae with native species occurring in Sub-Saharan Africa and Asia. The Asian fauna of Argolis is revised in this study, resulting in the recognition of two species, and the Oriental genera Bardesanes Distant, 1909 and Neoklugia Distant, 1919 are here considered junior synonyms of Argolis. Taxonomic changes are proposed accordingly in the present study, and the significant sexual dimorphism, systematic relationships, and distribution of Argolis are also discussed. Abstract The assassin bug genus Argolis Stål, 1861 (Hemiptera: Reduviidae: Stenopodainae) has a disjunct distribution in Sub-Saharan Africa and Asia. In the present study, the Asian species of Argolis are revised. Two species are recognized, redescribed, and illustrated, with the following new subjective synonyms and new combination proposed: Argolis Stål, 1861 = Bardesanes Distant, 1909, syn. nov. = Neoklugia Distant, 1919, syn. nov.; A. farinator (Reuter, 1882) = N. typica Distant, 1919, syn. nov. = B. sericenotatus Livingstone & Ravichandran, 1989, syn. nov.; A. signata (Distant, 1909), comb. nov. (transferred from Bardesanes) = Caunus noctulus Hsiao, 1977, syn. nov. Lectotypes for C. farinator, B. signatus, and N. typica are designated. A key to separate the two Asian species of Argolis is provided. The sexual dimorphism, systematic relationships, and distribution of Argolis are discussed. Argolis is newly recorded from Laos, Pakistan, and Vietnam.


Introduction
The assassin bug subfamily Stenopodainae is a large but relatively less researched group of Reduviidae, comprising 112 described genera and approximately 770 described species [1][2][3].Some genera are speciose and widely distributed, such as the cosmopolitan Oncocephalus Klug, 1830 (>200 spp.) and Pygolampis Germar, 1817 (91 spp.) and the Old World Sastrapada Amyot & Serville, 1843 (71 spp.).However, 52 genera of Stenopodainae are monotypic, and most of them lack sufficient descriptions and/or illustrations, which makes their identity questionable and, therefore, largely impedes our understanding of relationships within the subfamily.Our previous studies have reviewed some genera of Stenopodainae from Asia [4,5], aiming to increase our knowledge of the diverse Asian stenopodaine fauna.The present study is another part of this topic, revising the Asian fauna of the genus Argolis Stål, 1861.
Argolis, more commonly known as Caunus Stål, 1865 in the past few decades, currently contains 16 described species, with its highest diversity occurring in the Afrotropical Realm between ocelli and one pair of tubercles on posterior head margin.Eye (Figure 5A,B,E,F) large, strongly protruding laterally, reniform in lateral view, dorsal margin remote from dorsal head margin and ventral margin distinctly surpassing ventral head margin, ventromedial margin nearly touching each other.Ocellus (Figure 5A,B,E,F) large, elevated, protruding laterodorsally.Antennal scape thickest, distinctly longer than head, weakly curved near apex; pedicel longest, slightly curved; flagellum short, gracile, distiflagellomere about two times as long as basiflagellomere.Labium (Figure 5B,F) nearly straight, tapering; visible segments I and II subequal in length; visible segment III shortest.Collum distinctly distinguished from postocular region of head.
Pronotum (Figure 5A,B,E,F) subtrapezoidal, length along midline slightly shorter than width across humeral angles; anterior margin slightly concave; anterolateral angles blunt, angulated or acute, usually projecting anterolaterally; anterior pronotal lobe distinctly shorter than posterior lobe, with median depression on posterior half and four small granulations arranged squarely on disc (sometimes indistinct); posterior pronotal lobe separated from anterior lobe by faint transverse sulcus, with shallow medial longitudinal furrow; lateral margin finely concave; humeral angles acute, slightly or distinctly protruding laterally; posterior margin oblique on lateral third, nearly straight or finely concave on middle third.Anterolateral angles of prosternum forming small acute processes (Figure 5B,F); fore acetabulum open.Scutellum (Figure 5A,B) elongate triangular, with one pair of small basolateral denticles; apical process narrow and acute, curved upwards.
Legs slender.Fore femur simple, lacking ventral spines or denticles; fore tibia straight, with tibial comb at apex of inner surface.Mid tibia slightly longer than mid femur.Hind femur reaching apex of abdomen; hind tibia distinctly longer than hind femur.Tarsal formula 3-3-3; tarsomere III longest, subequal to length of tarsomeres I and II combined.Claws narrow, simple in shape.Fossula spongiosa absent in all legs.
Hemelytron (Figure 6) reaching or slightly surpassing apex of abdomen in midline; corium with hexagonal cubital cell; membrane with typical two cells; M strongly curved laterally at base of apical external cell; basal margin of apical internal cell convex.
Abdomen elongate oval, with simple lateral margin; dorsal laterotergites narrowly exposed in dorsal view; ventral surface with median longitudinal ridge running from base of sternite II to apex of sternite VII.Posterior margin of sternite VI widely concave anteriorly (Figures 2C and 4C).Posterior margin of segment VII widely incised at midportion.Segment VIII clearly exposed in lateral and ventral views, with a widely concave posteromedian margin.
Male genitalia: Pygophore (Figures 7A-C and 8A-C) oblong, with a wide, flattened, widely concave superoposterior margin; transverse bridge slender; median process weakly developed.Paramere (Figures 7D-F and 8D-F) short, curved, covered with dense setae on apical two-thirds, with one subapical keel on inner surface, apically rounded.Phallus (Figures 7G-I and 8G-I) relatively small; basal plate extension longer than basal plate arms; dorsal phallothecal sclerite well developed, with a round posterior margin; struts slender, parallel in majority of their lengths and fused at apices; ventral sclerite of phallosoma developed, narrow; endosoma elongate, largely membranous.
Macropterous female (Figures 2D-F and 4D-F).Vestiture.Similar to that of male but differs in the following characteristics: antennal scape and basal half to three-fourths of pedicel only with tiny scale-like setae; flagellomeres and apical one-fourth to half of pedicel with short suberect setae and short, decumbent, whitish pubescence.
Structure.Similar to that of male but differs in the following characteristics: body robust, subfusiform (Figures 2D-F and 4D-F); head (Figure 5C,D,G,H) thickened, with postocular region nearly parallel-sided or weakly convergent posteriorly; eye (Figure 5C,D,G,H) smaller, moderately protruding laterally, ventral margin reaching ventral head margin in lateral view, ventromedial margin far remote from each other; ocellus (Figure 5C,D,G,H) small, slightly elevated; antennal scape short, distinctly shorter than head, curved; length of pronotum slightly longer than width across humeral angles; anterior pronotal lobe slightly shorter than posterior lobe; humeral angles blunt, angulated or acute, weakly protruding laterally (Figure 5C,D,G,H); apical process of scutellum horizontal or slightly curved upwards (Figure 5C,D,G,H); hind femur not reaching apex of abdomen; hemelytron reaching anterior portion of tergite VI to posterior portion of tergite VIII in midline; abdomen subfusiform, with dorsal laterotergites widely exposed in dorsal view; posterior margin of sternite VI sharply incised anteriorly at midpoint (Figures 2F and 4F).
Diversity and distribution.Argolis currently contains 16 species, 14 of which are in the Afrotropical Realm and two in South and East Asia.

Key to the Asian Species of Argolis
1 Body generally yellowish brown (Figures 1 and 2); lateral margin of pronotum with one granulation at midpoint (Figure 5I); tibiae yellowish brown (Figure 2); ventral surface of pygophore not emarginate subapically in lateral view (Figure 7B).
Redescription.Macropterous male (Figure 2A-C).Coloration.Generally yellowish brown.Head with ocellar tubercle and eye blackish brown; ocellus, oblique stripe outside of ocellus and ventral surface of head brown to dark brown.Antennal flagellomeres and apex of pedicel dark brown.Labium with lateral surface brown and ventral surface yellow.Pronotum with dark brown median longitudinal stripe nearly throughout its length, stripe narrow on anterior lobe, wide and separated on posterior lobe (Figure 5A); lateral margin and apical process of scutellum slightly darkened; thoracic sterna and ventral third of pleura pale brown to brown.Legs unicolored; hind femur dark brown, with apical third slightly darkened (Figure 2A-C); inner surface of base of hind tibia dark brown (Figure 2A,C).Hemelytron pale greyish brown, with basal portion, exocorium and veins pale yellowish brown to yellowish brown (Figure 6A); corium with large blackish patch almost filled cubital cell, and small, oblique triangular, blackish patch at base of cubital cell (Figure 6A); clavus with blackish stripe along medial border, gradually becoming paler towards apex (Figure 6A); membrane with elongate pale brown patch along outer border of apical internal cell, elongate whitish patch surrounded by large, irregular, dark brown patch in apical external cell, and small, elongate, blackish patch at apex (Figure 6A).Basal, submedian and apical spots of each dorsal laterotergite yellow; ventral surface of abdomen with one pair of disrupted, obscure, brown lateral stripes; outer third of both sides of sternites mottled with pale brown suffusion.margin of mesopleuron, mesosternum, dorsal margin of metapleuron, and ante gin of metasternum with very short, decumbent, whitish pubescence; pronotum eral narrow, longitudinal, glabrous areas on disc (Figure 5A,E).Legs with shor decumbent to suberect, thick setae arising from small tubercles.Abdominal stern dense, short, decumbent, whitish pubescence; lateral and posterior margins of VII with short scale-like setae.2A-C and 4A-C).Head (Figure 5A,B,E, elongate, subcylindrical, shorter than pronotum; anteocular region more than two tim as long as postocular, nearly parallel-sided in dorsal view; mandibular plates sho slightly to distinctly divergent anteriorly, with sharp apices; antennifer with small seti erous lateral process; postocular region gradually convergent posteriorly, with deep lo gitudinal sulcus between ocelli and one pair of tubercles on posterior head margin.E (Figure 5A,B,E,F) large, strongly protruding laterally, reniform in lateral view, dorsal ma gin remote from dorsal head margin and ventral margin distinctly surpassing ventr head margin, ventromedial margin nearly touching each other.Ocellus (Figure 5A,B,E, large, elevated, protruding laterodorsally.Antennal scape thickest, distinctly longer tha head, weakly curved near apex; pedicel longest, slightly curved; flagellum short, gracil distiflagellomere about two times as long as basiflagellomere.Labium (Figure 5B,F

Vestiture.
As in the redescription of the genus.Setigerous tubercles on head and prothorax prominent.
Structure.Head (Figure 5A,B) 1.3 times as long as width across eyes, width across eyes 2.2 times as broad as interocular space; anteocular region 2.7 times as long as postocular; mandibular plates slightly divergent anteriorly, slightly curved upwards; postocular region with paired prominent tubercles on posterior head margin.Antennal scape 1.1 times as long as head; pedicel 1.1 times as long as scape.Pronotum (Figure 5A,B) with length along midline 0.9 times as long as width across humeral angles; anterolateral angles acute, projecting anterolaterally; anterior lobe with four distinct granulations on disc, and one pair of small granulations laterally before transverse sulcus (Figure 5I); humeral angles distinctly protruding posterolaterally (Figure 5I).Cubital cell of hemelytron relatively small, shorter than half of length of apical external cell (Figure 6A).Abdomen 2.15 times as long as its maximum width.
Hemelytron (Figure 6) reaching or slightly surpassing apex of abdomen in midline; corium with hexagonal cubital cell; membrane with typical two cells; M strongly curved laterally at base of apical external cell; basal margin of apical internal cell convex.
Abdomen elongate oval, with simple lateral margin; dorsal laterotergites narrowly exposed in dorsal view; ventral surface with median longitudinal ridge running from base of sternite II to apex of sternite VII.Posterior margin of sternite VI widely concaved anteriorly (Figures 2C and 4C).Posterior margin of segment VII widely incised at midportion.Segment VIII clearly exposed in lateral and ventral views, with a widely concave posteromedian margin.

Macropterous female (Figures 2D-F and 4D-F).
Vestiture.Similar to that of male but differs in the following characteristics: antennal scape and basal half to three-fourths of pedicel only with tiny scale-like setae; flagellomeres and apical one-fourth to half of pedicel with short suberect setae and short, decumbent, whitish pubescence.
Structure.Similar to that of male but differs in the following characteristics: body robust, subfusiform (Figures 2D-F and 4D-F); head (Figure 5C,D,G,H) thickened, with postocular region nearly parallel-sided or weakly convergent posteriorly; eye (Figure 5C,D,G,H) smaller, moderately protruding laterally, ventral margin reaching ventral head margin in lateral view, ventromedial margin far remote from each other; ocellus (Figure 5C,D,G,H) small, slightly elevated; antennal scape short, distinctly shorter than head, curved; length of pronotum slightly longer than width across humeral angles; anterior pronotal lobe slightly shorter than posterior lobe; humeral angles blunt, angulated or acute, weakly protruding laterally (Figure 5C,D,G,H); apical process of scutellum horizontal or slightly curved upwards (Figure 5C,D,G,H); hind femur not reaching apex of  2D-F).Coloration.Similar to that of male.Dorsal laterotergites of abdomen largely dark brown, with indistinct yellowish suffusion posterolaterally; tergite VIII with one pair of blackish spots in anterior half (Figure 9A).

Macropterous female (Figure
Vestiture.As in the redescription of the genus.Short suberect setae occupying apical half of antennal pedicel. Structure.Similar to that of male but differs in the following characteristics: head (Figure 5C,D) 1.7 times as long as width across eyes, width across eyes 1.75 times as broad as interocular space; anteocular region 2.8 times as long as postocular; mandibular plates nearly parallel, horizontal.Antennal scape 0.4 times as long as head; pedicel 1.45 times as long as scape.Humeral angles of pronotum angulated (Figure 5C).Apical process of scutellum slightly curved upwards (Figure 5D).Abdomen 2.1 times as long as its maximum width.
Female genitalia: Apical half of tergite IX relatively broad in dorsal view (Figure 9A); valvula II relatively longer, with sharp apex (Figure 9B,C).
abdomen; hemelytron reaching anterior portion of tergite VI to posterior portion of tergite VIII in midline; abdomen subfusiform, with dorsal laterotergites widely exposed in dorsal view; posterior margin of sternite VI sharply incised anteriorly at midpoint (Figures 2F  and 4F).
Remarks.Reuter [12] described Caunus farinator based on an unspecified number of female specimens (syntypic) from "Tranquebar" (=Tharangambadi; Tamil Nadu, India).The type depository provided in the original description is "Mus.Havn. in Coll.Westermanni", which refers to Westermann's collection in ZMUC.One female specimen (Figure 1A-C), matching the original collection data and bearing a red type label and an O.M. Reuter's handwritten identification label, was found in the collection of ZMUC.This specimen fits the original description and therefore is a syntype of C. farinator, and it is here designated as the lectotype of this species.
Neoklugia typica was described based on an unspecified number and sex of specimens (syntypic) from "S.India; Chikkaballapura" (=Chikkaballapura; Karnataka, India) [38].Nine specimens (seven males and two females) preserved in the collection of the BMNH match the original collection data.Since Neoklugia was apparently described from males as Distant [38] stated that the "first joint of the antennae [was] about as long as the pronotum, distinctly finely hirsute", the females cannot be types.Of the seven males, two have the registration number "1915-60", two have "1926-171" and the other three have "1930-599".The registration numbers indicate when the specimens were acquired by BMNH, and any specimen obtained after the original description may or may not be a type [48,49].Therefore, only the two males with the registration number "1915-60" are considered syntypes of N. typica.We here select the specimen bearing a red holotype disc and a W.L. Distant's handwritten identification label (Figure 1D,E) as the lectotype of this species.Examination of the female specimens collected together with the males recovered sexual dimorphism in this species, which is a common phenomenon in Argolis (see discussion below).Based on the similarity of females to the female type of A. farinator we concluded that the species are conspecific.Therefore, we propose the following new subjective synonymy: Argolis farinator (Reuter, 1882) = Neoklugia typica Distant, 1919, syn.nov.
Bardesanes sericenotatus was described based on a male holotype and two paratypes (one male and one female) from Vadavalli, Tamil Nadu, India [43].A dorsal habitus illustration of the male was provided along with the original description, and the phallus of this species was illustrated by Ravichandran et al. [44].Although the type material of this species deposited in BUCI was not examined during this study, several morphological characters documented in Livingstone & Ravichandran [43] and Ravichandran et al. [44] indicate the species agrees perfectly with A. farinator in body size and coloration, as well as the following morphological characters: "postocular area with a tubercular process behind each ocellus, porrectly pointing backward[s] from vertex"; "anterior lobe [of pronotum] with a pair of minute discal tubercles on either side of the median foveation"; "two pairs of discal small tubercles in the anterior lobe of pronotum".As these two species could not be distinguished by morphological characters, and also due to the proximality of their type localities, the following new subjective synonymy is proposed: Argolis farinator (Reuter, 1882) = Bardesanes sericenotatus Livingstone & Ravichandran, 1989, syn.nov.[62] (type material); Zhao and Cai (2007: 199) [ Diagnosis.Body generally dark brown (Figures 3 and 4); head and prothorax with minute setigerous tubercles (Figure 5E-H); anteocular region less than 2.2 times as long as postocular; lateral margin of pronotum simple, lacking small granulation (Figure 5J); tibiae yellowish brown, each with one basal and one subbasal dark brown annuli (Figure 4); cubital cell of hemelytron longer than half of length of apical external cell (Figure 6B); pygophore distinctly expanded posteriorly in dorsal view (Figure 8A), ventral surface strongly emarginate subapically in lateral view (Figure 8B); paramere stout, with wide subapical keel enclosing an arc with apex of paramere (Figure 8D-F).
Redescription.Macropterous male (Figure 4A-C).Coloration.Generally dark brown.Head with middle of postocular region (Figure 5E), eye and ventral surface blackish brown; ocellus brown.Antennal scape and basal two-thirds of pedicel yellowish brown, flagellomeres and apical third of pedicel dark brown.Labium with lateral surface brown and ventral surface yellow.Pronotum with indistinct, blackish, medial longitudinal stripe nearly throughout its length, stripe narrow on anterior lobe, wide and divergent on posterior lobe (Figure 5E); scutellum slightly darkened on disc, with apical process slightly paler; thoracic pleura and sterna with indistinct irregular darkened suffusion.Femora brown, each with base and apical third dark brown (Figure 4A-C); tibiae yellowish brown, each with base, narrow subbasal annulus and apex dark brown (Figure 4A-C).Hemelytron with coriaceous proximal portion brown and membrane dark greyish brown (Figure 6B); corium with large blackish patch almost filled cubital cell, and small, oblique triangular, blackish patch and narrow, oblique, blackish stripe at base of cubital cell (Figure 6B); clavus with blackish stripe along medial border, slightly becoming paler towards apex (Figure 6B); membrane with elongate whitish patch surrounded by large, irregular, blackish patch in apical external cell, and small, elongate, blackish patch at apex (Figure 6B).Basal, submedian and apical spots of each dorsal laterotergite yellow; ventral surface of abdomen yellowish brown at middle, with one pair of disrupted, obscure, blackish lateral stripes; sternite VII, segment VIII and pygophore slightly darkened.
Vestiture.As in the redescription of the genus.Setigerous tubercles on head and prothorax minute.
Structure.Head (Figure 5E,F) 1.2 times as long as width across eyes, width across eyes 2.35 times as broad as interocular space; anteocular region 2.2 times as long as postocular; mandibular plates distinctly divergent anteriorly, slightly curved upwards; postocular region with paired blunt tubercles on posterior head margin.Antennal scape 1.2 times as long as head; pedicel 1.15 times as long as scape.Pronotum (Figure 5E,F) with length along midline 0.9 times as long as width across humeral angles; anterolateral angles blunt to angulated; anterior lobe with four granulations on disc, posterior pair indistinct; humeral angles distinctly protruding laterally (Figure 5J).Cubital cell of hemelytron relatively large, longer than half of length of apical external cell (Figure 6B).Abdomen 2.1 times as long as its maximum width.
Macropterous female (Figure 4D-F).Coloration.Similar to that of male.Dorsal laterotergites of abdomen largely dark brown, with indistinct light-colored spots; tergite VIII with one pair of faint yellowish brown spots extending to anterior portion of tergite IX (Figure 9D).
Vestiture.As in the redescription of the genus.Short suberect setae occupying apical one-fourth of antennal pedicel.
Structure.Similar to that of male but differs in the following characteristics: head (Figure 5G,H) 1.6 times as long as width across eyes, width across eyes 1.7 times as broad as interocular space; anteocular region 2.1 times as long as postocular; mandibular plates slightly divergent anteriorly, horizontal.Antennal scape 0.5 times as long as head; pedicel 1.6 times as long as scape.Humeral angles of pronotum blunt (Figure 5G).Apical process of scutellum blunt, horizontal (Figure 5H).Abdomen 2.15 times as long as its maximum width.
Bionomics.Published bionomic records of this species are from China and Japan.Its habitat was speculated to be wetlands near paddy fields [46,67], but most specimens were collected under lights [ [46,52,68]; present study].Ren [52] recorded that this species inhabits the rhizosphere of plants or on the ground, and the females lay their eggs in soil crevices, near soil clumps or under loose soil.It is probably a generalist predator, Tian [53] recorded lepidopteran caterpillars as its preys in Shandong, China.The surface structure of its eggs was described by Ren [52] based on SEM observations.Okuda and Uchida [68] reported a nymph on mammal faeces with a forwardly pointed rostrum, but whether it was feeding on the juice of the faeces or preying on maggots, could not be confirmed.
Remarks.Bardesanes signatus was described based on an unspecified number and sex of specimens (syntypic) from "Burma; Karennee" (=Kayah, Myanmar) [36].A dorsal habitus and a lateral view of the head and prothorax were illustrated by Distant [37], along with a redescription of the species.One male syntype (Figure 3A-C) deposited in the BMNH and presumed to be the specimen illustrated by Distant [37] is here designated as the lectotype of this species.As Bardesanes is hereby considered a junior subjective synonym of Argolis (see discussion below), this species is transferred to the latter genus as A. signata (Distant, 1909), comb.nov.
The type material of Caunus noctulus consists of one male holotype and six paratypes (three males and three females, including one treated as the "allotype") [27].The holotype (Figure 3D-F) and three paratypes (one male and two females, including the "allotype") deposited in IZAS were examined during this study.Hsiao [27] distinguished his new species from B. signatus by the following morphological characters (in Chinese): anterolateral angles of pronotum prominent; mid femur longer than fore femur, both not curved; antennal scape relatively short, distinctly shorter than pedicel.A reexamination of the type materials of both species concluded that they were conspecific.The antennal scape of the lectotype of B. signatus is clearly shorter than the pedicel but ambiguously described as "subequal in length to the second joint [= pedicel]" by Distant [36]; the minor differences in the shape of the anterolateral angles of the pronotum are considered as minor individual variations; the seemingly curved fore and mid femora of the lectotype of B. signatus are perhaps due to a deformity during the individual development.Therefore, we propose the following new subjective synonymy: Argolis signata (Distant, 1909), comb.nov.= Caunus noctulus Hsiao, 1977, syn.nov.

Sexual Dimorphism in Argolis
Many subfamilies of Reduviidae are known to exhibit sexual dimorphism, and the morphological divergences between male and female of a certain species are sometimes extraordinary [74][75][76][77].Limited and extreme sexual dimorphism have been documented within Stenopodainae as well [7,78,79] and sexual dimorphism of Argolis was described in Villiers [7,8], Hsiao [27] and Cao et al. [6].The male and female of Argolis show differences in general habitus and several morphological character states summarized in Table 1.Some of the above characters were previously utilized to separate Argolis and Caunus [10,18,20,22], but Schouteden [11] first recognized that such differences were attributed to sexual dimorphism, and he therefore synonymized the two genera.Likewise, characters related to sexual dimorphism affected species-level classification within Argolis.For instance, A. farinator was originally described from the female, while the male was subsequently described as N. typica (see above under A. farinator).In order to avoid misidentification caused by sexual dimorphic characters, both sexes of the two Asian species of Argolis are redescribed in this study.However, some of the 14 described species from the Afrotropical Realm are still known from a single sex, and their identities need to be verified in future studies.

Evaluation of Bardesanes and Neoklugia
Distant [36] treated his genus Bardesanes as "a genus to be placed after Caunus in the British Indian enumeration", but he did not conduct a morphological comparison of these two genera.Livingstone and Ravichandran [29] included these two genera in their key to the South Indian genera of Stenopodainae.They used the morphology of the antennal scape to separate Caunus (now Argolis) and Bardesanes, but this character is sexually dimorphic as discussed above and therefore not appropriate for genus-level classification.Based on a redescription of the male of A. farinator (misidentified as B. signatus), Chandra et al. [47] listed four characters to differentiate Bardesanes and Caunus.We examine the lectotype (here designated) of B. signatus (the type species of Bardesanes) and make the following comments: (1) Chandra et al. [47] mentioned that the fore femur is spined in Bardesanes but unarmed in Caunus; this is not true because the fore femur of B. signatus only has some small setigerous tubercles on its ventral surface but no spines or denticles.(2) The visible labial segment I is "little longer than" segment II in Bardesanes, while in Caunus they are subequal in length [47]; based on the examination of a series of specimens of the two Asian species, we do not find clear differences in the length of the two basal labial segments.
(3) The antennal scape is nearly as long as the pedicel in Bardesanes but shorter than the pedicel in Caunus [47]; this character was inaccurately described by Distant [36,37], because the pedicel of the lectotype of B. signatus is clearly longer than the scape; the pedicel is also more or less clearly longer than the scape in other conspecific specimens we have examined in this study; in the measurements provided by Chandra et al. [47], the pedicel of their specimen is significantly shorter than the scape, but this is the opposite of the state shown in their photo (Chandra et al., 2013: figure B [47]). ( 4) The apical process of the scutellum is described as "moderately curved upwards" in Bardesanes and "obliquely erect" in Caunus by Chandra et al. [47]; such descriptions are ambiguous and could not effectively distinguish the two genera; the apical process of the scutellum is more or less raised in our examined specimens, although it is weaker in females than in males; this is a minor individual variation and cannot be used to separate different genera.Consequently, Bardesanes could not be clearly distinguished from Argolis by morphological characters.
When describing Neoklugia, Distant [38] compared it with Oncocephalus.Most of the morphological characters listed by him match those of Argolis, except that fore femur is "only slightly or moderately incrassated, with a single series of slender short spinules beneath", and hind leg "with the femora and tibiae about or almost of equal length" [38].The examination of the type material of N. typica (the type species of Neoklugia) reveals that these two characters were inaccurately described by Distant [38]: the fore femur is not thickened and only has some small setigerous tubercles on its ventral surface; the hind tibia is significantly longer than the hind femur.Since N. typica is also confirmed as the male of A. farinator (see above under A. farinator), there seems no reason for maintaining Neoklugia as a distinct genus based on morphological characters.
In conclusion, we propose the following new subjective synonymies: Argolis Stål, 1861 = Bardesanes Distant, 1909, syn.nov.= Neoklugia Distant, 1919, syn.nov.Argolis (as Caunus) was usually confused with Bardesanes in some previous studies [46,47,73], and Neoklugia was almost never cited since its original description.Such confusion and neglect largely stem from the unclear identities of the two Asian species of Argolis and the resulting misidentifications.In the present study, the two Asian species of Argolis are redescribed and illustrated.In order to stabilize the nomenclature regarding C. farinator, B. signatus and N. typica, lectotypes of these species are designated.The differences between the two Asian Argolis species are summarized in Table 2.

Systematic Relationships of Argolis
Argolis has long been considered to be closely related to Oncocephalus [12,19,26,27,33].These two genera share a similar general habitus and the following morphological characters: head subcylindrical; eye reniform in lateral view, nearly touching (♂) or far removed (♀) in ventral view; ocellus elevated; scutellum with apical process, horizontal or slightly curved upwards; tarsal formula 3-3-3; fore and mid tibiae lacking fossula spongiosa; hemelytron with hexagonal cubital cell.These morphological similarities likely indicate a close phylogenetic relationship between Argolis and Oncocephalus, and it is also possible that Argolis is a specialized lineage within a more extensive Oncocephalus.A cladistic analysis with samples of both genera is needed to evaluate these possibilities.
Argolis can be distinguished from Oncocephalus in its current sense by the nearly straight labium (vs.distinctly curved in Oncocephalus) and the slender and ventrally unarmed fore femur (vs.strongly thickened with one or two rows of spiniferous tubercles in Oncocephalus).

Distribution of Argolis
Argolis has a disjunct distribution in the Old World, with 14 species occurring in sub-Saharan Africa, including Madagascar, and the other two distributed in Asia (Table 3).The two Asian species exhibit geographic isolation.Argolis farinator seems to be endemic to the Indian subcontinent, with most examined specimens from southern India (Figure 10).Our study extends the distribution of the species westward to Malir (southern Pakistan) and northward to Almora (northern India) and adds a new record for the species on the southern slopes of the Himalayas.
Argolis signatacomb.nov. is distributed in Southeast and East Asia, from the Indochinese Peninsula through southern and eastern China to the Japanese Archipelago, but two examined specimens were collected from Pedong (northern India) on the southern slopes of the Himalayas (Figure 10).Few specimens were collected on the Indochinese Peninsula, but further collecting could increase its distribution range in this area.The distribution of this species in China is mainly south of the Yangtze River, but it is also found more northerly in Shandong.In Japan, this species has been recorded in Honshu, Kyushu, Shikoku, and Tsushima Islands, but most collection records are concentrated in the Kanto Region [68,69].This species was recorded in Henan, China [6] and the Korean Peninsula [35], but no voucher specimen from these localities could be examined during this study.
The biogeographic background of the distribution of Argolis is unclear.Previous phylogeographical studies have suggested that the Afrotropical, Malagasy, and Oriental reduviid faunas are closely related, and transoceanic dispersal has happened among these regions [84,85].Whether this hypothesis is also appropriate for Argolis requires testing in future studies.In the case of the Asian fauna, the Indo-Myanmar Mountain ranges may have been a geographical barrier between A. farinator and A. signata, while the Japanese populations of A. signata are probably more closely related to those in southeastern China, but the demographic history of the genus in East Asia needs to be further analyzed.
) near straight, tapering; visible segments I and II subequal in length; visible segment III shorte Collum distinctly distinguished from postocular region of head.Pronotum (Figure 5A,B,E,F) subtrapezoidal, length along midline slightly short than width across humeral angles; anterior margin slightly concave; anterolateral angl
Insects 2023, 14, x FOR PEER REVIEW 10 of 27 setae on apical two-thirds, with one subapical keel on inner surface, apically rounded.Phallus (Figures 7G-I and 8G-I) relatively small; basal plate extension longer than basal plate arms; dorsal phallothecal sclerite well developed, with round posterior margin; struts slender, parallel in majority of their lengths and fused at apices; ventral sclerite of phallosoma developed, narrow; endosoma elongate, largely membranous.