Sirthenea Spinola, 1837

Chłond, Dominik, 2018, A taxonomic revision of the genus Sirthenea (Hemiptera: Heteroptera: Reduviidae) of the Old World, Zootaxa 4520 (1), pp. 1-85 : 5-8

Genus Sirthenea Spinola, 1837

Sirthenea Spinola, 1837: 100 . Type species: Reduvius carinatus Fabricius, 1798 (by monotypy).

Monogmus Horváth, 1909: 357 (as subgenus of Sirthenea ). Type species: Sirthenea atrocyanea Horváth, 1909 (by original designation).

Sirtheneana Miller, 1958: 72 . Type species: Sirtheneana nigronitens Miller, 1958 (by original designation). Synonymized by Willemse (1985: 16).

Diagnosis. Distinguished from other genera of Peiratinae by the following combination of characters: body ( Fig. 1 ) and anteocular part of head distinctly elongated; head triangular in dorsal view and elongated in horizontal plane in lateral view, anteocular part straight, with tip directed frontally; antennal insertion approximately at middle of anteocular part of head ( Figs. 153–155 ); fossula spongiosa large, usually present only on fore tibia, exceptionally on fore and middle tibiae ( S. laevicollis ) ( Figs. 159–163 ).

Redescription. Coloration: Ground color dark (brown or black) with pale markings on legs, hemelytron, abdomen and connexives ( Figs. 193–210 ).

Structure: Body distinctly elongated ( Fig. 1 ), small to large, robust ( Fig. 2 ) or slender ( Fig. 131 ) (females, including brachypterous forms, larger than males). Head, pronotum and scutellum shiny, hemelytron with slightly granulated corium and dull membrane covered by very small and distinctly curved setae, with apices direct into apex of wing. Vestiture medium-sized to large, erect or semierect.

Head triangular with a distinctly elongated anteocular part and a distinct interocular furrow (middle part distinctly curved in acute angle) ( Fig. 1 ). In frontal view head almost cylindrical with convex or slightly elevated ventral and dorsal surfaces; lateral surfaces slightly flattened. Mandibular plate small, subtriangular, with sharp apical part. Maxillary plates large, with sharp and distinctly depressed apex. Clypeus slender, distinctly facing downward with gibbose basal part. Labrum triangular, slightly gibbose in basal part with sharp or slightly rounded apex. Antennifer distinctly visible, placed dorsolaterally with downward apices. Point of antennal insertion in middle of anteocular part of head. Scape shortest and most robust segment, slightly curved and gradually narrowing towards its base, either not reaching, reaching (subgenus Sirthenea ) ( Fig. 1 : SC) or visibly surpassing (subgenus Monogmus ) ( Fig. 28) apex of head. Scape with medium-sized setae (thin, erect and thick, adherent). Pedicel longest, thinner than scape, covered with short, dense, adherent setae and a few very long, trichobothrial setae ( Figs. 169–182 ). Basi- and distiflagellum distinctly thinner than scape and pedicel. Eyes globular, large, in lateral view with rounded anterior margin and curved, visibly flattened posterior margin ( Figs. 153–155 ). Posterior margin of an eye in laterial view S- ( Fig. 190 ) or U-curved ( Fig. 189 ). Facets pigmented or without pigment; marginal facets frequently not pigmented or pigmentation shows different patterns from more central facets. Postocular part of head slightly convex dorsally with variably-sized (mostly large) setae. Ocelli not pigmented or reduced in some brachypterous forms ( Fig. 94 ), placed on very wide, flat or slightly elevated tubercles. Labium relatively slender, arcuate. First visible labial segment short and stout with slight sculpturation on ventral surface. Second visible labial segment, laterally flattened and gradually narrowing into apex, basally distinctly convex on ventral surface. Third visible labial segment long and slender with wider basal part.

Thorax. Anterolateral angles of collar visibly not or delicately enlarged. Anterior pronotal lobe trapezoidal ( Fig. 1 : APL), rounded ( Fig. 132 ) or elongate ( Figs. 122 , 131 ) in dorsal view and relatively flattened in lateral view, visibly enlarged in brachypterous forms ( Figs. 42 , 66 , 94 ). Anterior pronotal lobe with distinct median pronotal apophysis and visible dull sulci (barely visible in representatives of subgenus Monogmus , except median sulcus) ( Fig. 1 : MS). Median sulcus ( Fig. 1 : MS) thin and slightly visible, connected with slightly visible frontal dull area, placed along collar. Latero-internal sulci ( Fig. 1 : LIS) distinctly depressed and visible, arcuate and elongated along miedial part of collar. Latero-medial sulci ( Fig. 1 : LMS) slightly arcuate and gradually narrowing into apex. Basal part connected with lateral margin of anterior pronotal lobe. Latero-external sulci ( Fig. 1 : LES) arcuate, thin and distinctly depressed. Basal part of latero-external sulci connected with transversal suture. Transversal suture deeply depressed. Posterior pronotal lobe with elevated medial part and distinctly lower lateral parts. Posterior margin of posterior pronotal lobe slightly ( Fig. 28) or distinctly ( Fig. 15 ) curved. Pronotum covered by various sized setae. Proepisternum and proepimeron large, similar in size and placed to right angle to each other with ridges connected ( Fig. 191 ) or not ( Fig. 192 ) in entire length. Surface of propleura distinctly pointed. Mesepisternum large, mesepimeron distinctly smaller, vertically elongated. Metepisternum subtriangular, distinctly pointed. Proepisternal process distinctly elongated and gradually thinner into apex with thin stridulitrum. Mesosternum with distinct carina, delicately wrinkled by transversal sculpturation, metasternum delicately elevated and with slightly curved posterior margin. Metapleura with two complete ridges ( Fig. 188 ) or internal ridge incomplete. Thorax covered by variably-sized setae. Scutellum triangular with enlarged and elevated margin and distinctly depressed cental part. Apex rounded, short ( Fig. 15 ) or elongated ( Fig. 122 ). Legs relatively short and robust. Fore coxa flattened on outer surfaces. Fore and hind coxa elongated, middle coxa almost globular. All trochanters flattened. All femur flattened laterally. Fore femur distinctly enlarged, dorsally arcuated. Middle and hind femurs slightly curved in ventral view. Fore tibia with large fossula spongiosa, reaching amost half of apical part of tibia ( Fig. 28). Middle tibia without fossula spongiosa or with thin and relatively long fossula spongiosa on about apical third of tibia ( S. laevicollis , Figs. 159–163 ). Fore and mid tibia apically covered by dense, spine-like setae. All tibia gradually enlarged into apex ( Fig. 1 : TI). First tarsomere smallest; combined lengths of first and second tarsomeres greater than third tarsomere ( Fig. 1 : TA1– 3). Claws large with small indentation near basal part. Legs covered by various sized setae.

Hemelytron slender, not reaching (females) or surpassing (males) apex of abdomen in macropterous forms, distinctly shortened in brachypterous forms, covered by various sized setae on dull corium ( Figs. 167, 168 ). Membrane dull, large, distinctly wrinkled, covered by very small, distinctly curved setae with apices directed towards apex ( Figs. 164–168 ). Apical internal cell distinctly smaller than apical external cell ( Fig. 1 : AIC, AEC).

Abdomen fusiform, distinctly larger and more cylindrical in females. Middle part of sternite of second abdominal segment and anterior part of sternite of third abdominal segment with a median carina. Abdomen slightly flattened in middle part of each sternite. Dorsal and ventral connexival suture distinctly visible. Spiracles III–VI placed distant ( Fig. 185 ), very near ( Fig. 186 ) or fused ( Fig. 187 ) with ventral connexival suture. Connexives large and vertically oriented.

Male genitalia: Pygophore asymmetrical, delicately flattened laterally and globular in shape. Median process of pygophore bent on right side. Aedeagus slightly elongated, with different sized basal plate and pedicel, as well as various shape and size of dorsal phallothecal sclerite. Parameres curved, enlarged in apical part, with sharp process on apex.

Female genitalia: Valvifer I quadrangular, valvula II triangular. Styloids triangular or with slightly rounded apices.

Distribution, habitat and biology. The genus is distributed in tropical and subtropical areas around the equator, extending to neighbouring temperate regions. A previous analysis ( Chłond & Bugaj-Nawrocka 2015a) of niche preferences based on the known distribution data of Sirthenea species indicated that, in particular, they prefer tropical and temperate climates. The present study found that most species occurring in Africa colonize areas of tropical climate, but in Asia, Australia and Oceania, some species extend broadly into temperate regions as well. However, in Asia, a lot of occurrences are concentrated in South Korea, dominated by continental climate. Among all individuals of Sirthenea examined, 54.2% were collected in tropical and subtropical moist broadleaf forests, located in a belt around the equator, mostly in the Congo basin of central Africa and in coastal West Africa, parts of the Indian subcontinent, Indonesia and New Guinea. Of the remaining individuals most have been collected from temperate broadleaf and mixed forest biomes primarily in central China. The lowest proportion of individuals originated from tropical and subtropical grassland, savanna and shrubland biomes that are widespread in Africa, South Asia and Australia. Similar results were found in earlier publications regarding climate preferences of other groups of Reduviidae ( Chłond & Bugaj-Nawrocka 2014, 2015b; Chłond et al. 2015).

Most specimens of Sirthenea species studied during the present study were collected with light traps or on the ground often covered by fallen leaves or other plant parts, confirming the information provided by Readio (1927) and Willemse (1985). Willemse (1985), Chłond & Bugaj-Nawrocka (2015a), and Chłond et al. (2017) increased our knowledge about the ecology of some species. The majority of the individuals examined during this study were collected in lowland areas (mainly at 0–200 m above sea level), which is consistent with the observations of Willemse (1985); only a few specimens were collected over 1400 m above sea level. There is one record of Sirthenea peruviana Drake & Harris, 1945 , collected in Peru at an altitude of 3328 m, representing the highest known locality of the genus ( Chłond & Bugaj-Nawrocka 2015a), previously it was a specimen of S. vidua collected at an altitude of about 1800 m ( Willemse 1985).

Figures

FIGURE 1. General morphology of Sirthenea: AAP—anterolateral angles of the anterior collar of the pronotum; ADapodeme depression of pronotum; AEC—apical external cell; AH—apodeme depression of head; AIC—apical internal cell; APL—anterior pronotal lobe; AT—antennifer; BF—basiflagellum; CL—clavus; CO—anterior collar of pronotum; DFdistiflagellum; FE—femur; FS—fossula spongiosa; HL—head length; IO—interocellar distance (synthlipsis); IS—intercalar segment of antenna; LAP—length of anteocular part of the head; LES—latero-external sulcus; LPPL—lateral parts of posterior pronotal lobe; LIS—latero-internal sulcus; LPP—length of postocular part of the head; LMS—latero-medial sulcus; MSmedian sulcus; OC—ocelli; PD—pedicel; PPL—posterior pronotal lobe; SC—scape; SCU—scutellum; TA1—tarsomere I; TA2—tarsomere II; TA3—tarsomere III; TC—tubercles of ocelli; TI—tibia; TR—trochanter.

FIGURE 2. Sirthenea africana Distant, 1903—dorsal habitus.

FIGURE 15. Sirthenea flaviceps (Signoret, 1860)—dorsal habitus.

FIGURE 42. Sirthenea rodhaini Schouteden, 1913—brachypterous female, dorsal habitus.

FIGURE 66. Sirthenea dimidiata Horváth, 1911—brachypterous female, dorsal habitus.

FIGURE 94. Sirthenea kali sp. nov.—dorsal habitus.

FIGURE 122. Sirthenea setosa sp. nov.—dorsal habitus.

FIGURE 131. Sirthenea laevicollis Horváth, 1909—macropterous male, dorsal habitus.

FIGURE 132. Sirthenea laevicollis Horváth, 1909—brachypterous female, dorsal habitus.

FIGURES 153–155. Head in lateral view: 153—Sirthenea picescens Reuter, 1887; 154—S. kali sp. nov.; 155—S. nigronitens (Miller, 1958).

FIGURES 159–163. Fossula spongiosa on middle tibia of Sirthenea laevicollis Horváth, 1909: 159—fossula on middle tibia of brachypterous female; 160—SEM image of fossula spongiosa on middle tibia of male; 161—SEM image of apical part of fossula spongiosa on middle tibia of male; 162—SEM image of apical part of fossula spongiosa on middle tibia of male; 163— SEM image of setae of fossula spongiosa on middle tibia of male.

FIGURES 193–196. Color figures of habitus: 193—Sirthenea africana Distant, 1903; 194—S. flaviceps var. adelpha Horváth, 1909; 195—S. flaviceps var lugubris Horváth, 1909; 196—S. picescens Reuter, 1887.

FIGURES 197–200. Color figures of habitus: 197—Sirthenea rodhaini Schouteden, 1913; 198—S. caiana Chłond, 2008; 199—S. dimidiata Horváth, 1911, male; 200—S. dimidiata, female.

FIGURES 201–204. Color figures of habitus: 201—Sirthenea flavipes (Stål, 1855); 202—S. flavipes var. apicalis Horváth, 1909; 203—S. kali sp. nov.; 204—S. nigronitens (Miller, 1958).

FIGURES 205–208. Color figures of habitus: 205—Sirthenea nitida Chłond, 2008; 206—S. nigra Cai & Tomokuni, 2004; 207—S. setosa sp. nov.; 208—S. obscura (Stål, 1866).

FIGURES 209–210. Color figures of habitus: 209—Sirthenea laevicollis Horváth, 1909, male; 210—S. laevicollis Horváth, 1909, female.

FIGURES 169–182. Trichobothrial setae on pedicel: 169—Sirthenea africana Distant, 1903; 170—S. flaviceps (Signoret, 1860); 171—S. picescens Reuter, 1887; 172—S. rodhaini Schouteden, 1913; 173—S. caiana Chłond, 2008; 174—S. dimidiata Horváth, 1911; 175—S. flavipes (Stål, 1855); 176—S. kali sp. nov.; 177—S. nigronitens (Miller, 1958); 178—S. nitida Chłond, 2008; 179—S. nigra Cai & Tomokuni, 2004; 180—S. setosa sp. nov.; 181—S. laevicollis Horváth, 1909; 182—S. obscura (Stål, 1866).

FIGURES 188–192. 188—Ridges of metapleura of Sirthenea caiana Chłond, 2008; 189—U-shape posterior margin of an eye of S. obscura (Stål, 1866); 190—S-shape posterior margin of an eye of S. flaviceps (Signoret, 1860); 191—Ridges of proepisternum and proepimeron of S. africana Distant, 1903; 192—Ridges of proepisternum and proepimeron of S. nigronitens (Miller, 1958).

FIGURES 164–168. Hemelytron of Sirthenea flavipes (Stål, 1855): 164—membrane; 165—membrane; 166—membrane; 167—apical part of corium; 168—setae on apical part of corium.

FIGURES 183–187. 183—Apical part of anterior pronotal lobe of Sirthenea flavipes (Stål, 1855); 184—Apical part of anterior pronotal lobe of S. picescens Reuter, 1887; 185—Spiracles of S. flavipes (Stål, 1855); 186—Spiracles of S. laevicollis Horváth, 1909; 187—Spiracles of S. nitida Chłond, 2008.