Rhyparoclava, Kment & Hemala & Baňař, 2016

Kment, Petr, Hemala, Vladimír & Baňař, Petr, 2016, Rhyparoclava pyrrhocoroides, a new genus and species of autapomorphic Rhyparochromidae with clavate antennae from Madagascar (Hemiptera: Heteroptera), Acta Entomologica Musei Nationalis Pragae 56 (2), pp. 517-545 : 522-536

Rhyparoclava gen. nov.

Type species. Rhyparoclava pyrrhocoroides sp. nov., here designated.

Description. Structure. Body ( Figs 1–3 ) drop-shaped, small, convex ventrally, quite flat dorsally.

Head ( Figs 4–8 ) prognathous, ca. 1.5× longer than wide, preocular portion parallel-sided, outline W-shaped anteriorly. Eyes hemispherical, protruding from head outline by most of their width, narrowly separated from anterior margin of pronotum ( Figs 4, 6 ), postgenae (= tempora) short ( Figs 6, 8 ). Ocelli and cephalic trichobothria absent ( Figs 4, 6, 8 ). Vertex and frons regularly gibbose, slightly elevated above level of eyes in lateral view ( Fig. 8 ). Clypeus narrow, projecting forward, distinctly surpassing mandibular plates and apices of antenniferous tubercles ( Fig. 6 ), in lateral view slightly gibbose and distinctly elevated above mandibular plates ( Fig. 8 ). Antenniferous tubercles long, triangular, sharply and obliquely truncate apically, forming the lateral margin of head ( Figs 4–7 ), with one small tooth on each dorsal and ventral side of anterior margin, visible in lateral view ( Fig. 8 ), antennae inserted slightly anteroventrally. Antennae 4-segmented, as long as two thirds of body length, incrassate, clavate, widest across apical margin of basiflagellum (= antennal segment III) ( Figs 1–2 , 11 , 35 ). Antennal segments from shortest to longest: basiflagellum (III) = distiflagellum (IV) <scape (I) <pedicel (II). Scape ( Figs 9–10 , 35 ) short, cylindrical, slightly narrowing in anterior third of its inner margin, its outline distinctly separated from segments II–IV, collectively forming a compact club. Pedicel ( Figs 11 , 35 ) longest, nearly twice as long as basiflagellum or distiflagellum, connected with scape only by very thin base and then gradually widened towards truncate apex. Basiflagellum ( Figs 12 , 35 , 71 ) stout, cylindrical, only slightly widened basally, about half as long as pedicel and about the same length as distiflagellum. Distiflagellum ( Figs 12 , 35 , 71 ) conically tapering towards pointed apex. Ventral side of head flat ( Figs 5, 7 ), with a deep median depression starting from the posterior margin of bucculae and ending towards the apex of labial segment I ( Fig. 7 ). Bucculae short, reaching half-length of labial segment I ( Fig. 7 ), elongate, as high as labial segment I, their ventral margin only slightly rounded; bucculae hardly visible in lateral view ( Fig. 8 ). Labium slender ( Fig. 2 ); labial segment I ( Figs 5, 7 ) as long as ca. 2/3 of head length, segment II ( Figs 5 , 21) longest, segment III (Fig. 21) short, reaching between procoxae, segment IV shortest, reaching between mesocoxae.

Thorax. Pronotum trapezoidal ( Figs 4 , 16), with anterolateral angle 106° and posterolateral angle 67°; anterior margin concave, pronotal collar not developed; lateral margins explanate, in the form of a wide lamella bearing a single row of punctures; disc of pronotum slightly convex, anterior and posterior lobes indistinctly delimited.

Scutellum (Figs 18–20) slightly convex, in shape of ca. equilateral triangle.

Pro-, meso- and metasterna ( Figs 23–24 ) not keeled, with a very shallow groove medially. Vestibular scar well developed ( Figs 25–27 ), laterally modified into a long, narrowly V-shaped ostiole ( Figs 25–28 ). Peritreme ( Figs 25–27 ) short, auricle-shaped, slightly shorter than half the distance between ostiole and lateral margin of metapleuron, narrowing laterad, apex narrowly rounded, peritremal furrow distinct throughout peritreme except its extreme apex ( Figs 27–28 ). Peritremal surface oriented posteroventrally, elevated above surrounding pleuron. Evaporatorium surrounding ostiole and peritreme, occupying a large anteromedian portion of the metapleuron ( Figs 25–26 ), projecting medially between meso- and metacoxae ( Figs 25, 27 ); mesopleural evaporatorium small, occupying a narrow, subtriangular area between the mesopleural suture and the posterior margin of mesopleuron, narrowing laterad towards metathoracic spiracle ( Fig. 26 ). Metepimeroid hardly demarcated from metepimeron ( Fig. 25 ).

Fore wings brachypterous, fused together along claval commissure, membrane entirely absent ( Figs 1 , 3 , 19–20). Exocorium expanded, lamellate, widest anteriorly and gradually narrowing posteriad (Fig. 20), its proximal half bearing a single row of distinct punctures, distal half impunctate (punctuation apparent also on corresponding hypocostal lamina). Claval furrow obliterated, boundary of clavus and corium barely distinguishable (Figs 19–20). Veins (R+M, Cu, 1A+2A) slightly elevated, prominent among neighbouring rows of punctures (Fig. 20). Anterodistal angle of corium widely rounded, distal margin truncate, reaching ca. posterior margin of tergite IV or anterior margin of tergite V ( Figs 1 , 3 , 39), posterior margins of both hemelytra enclosing an obtuse angle (ca. 143°; Fig. 19). Hind wings absent.

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Figs 16–22. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs:16–17 – pronotum, dorsal view (16 – magnification 80×; 17 – detail of microsculpture, 400×); 18 – scutellum, dorsal view (100×); 19–20 – hemelytra, dorsal view (19 – 50×, 20 – 75×); 21 – prothorax, ventral view (75×); 22 – procoxae, ventral view (200×). Scale bars: 0.1 mm (Fig. 17), 0.2 mm (Figs 16, 22), 0.5 mm (Figs 18, 20, 21), 1 mm (Fig. 19). (SEM micrographs by P. Kment).

Legs. Pro- and metacoxae inserted close to each other, distance between pro- and metacoxae as wide as labial width, distance between mesocoxae slightly wider (Figs 21–23). Anterior surface of procoxa with small granule-like tubercle bearing single seta (Figs 21, 22: black arrow). Femora incrassate ( Figs 2 , 21), oval in cross-section, apically attenuated, pro- and metafemora somewhat more incrassate than mesofemur; mesofemur shorter than profemur, metafemur longer than profemur. Ventral surface of femora flat in apical third, on profemora with three serially arranged denticles anteroapically (Figs 21, 29). Protibia rounded in crosssection, slender, widened and flattened only apically, bearing a row of small spines ( Figs 30–31 ). Mesotibia shorter and metatibia longer than protibia; meso- and metatibia not widened apically, bearing two short spines on their apices ventrally. Tarsal segments from shortest to longest: II <III <I ( Fig. 32 ). Pretarsus with two slender, sickle-shaped claws accompanied by large fleshy pulvilli (with lamellate microsculpture on their ventral surface) and two short parempodia ( Figs 33–34 ).

Abdomen ( Figs 36–46 , 74–75 ) wide, almost rounded in outline posteriorly (connexival segments holding very wide obtuse angles), quite flat ( Fig. 37 ), only slightly convex ventrally, without a median keel or furrow ( Figs 36 , 46 ). Abdomen widest across posterolateral angles of segment V, slightly wider than fore wings ( Figs 1–2 ). Tergites II and III membranous, III slightly convex posteriorly (Figs 40–41). Tergites IV and V (Fig. 40) widely U-shaped; anterior margin of tergite VI concave, its posterior margin straight; posterior margin of tergite VII shallowly concave; tergite VIII widely rounded posteriorly. Vestiges of larval dorso-abdominal scent glands present between tergites III/IV ( Fig. 49 ), IV/V ( Fig.

50) and V/VI ( Fig. 51 ). Y-shaped suture between tergites III and IV vestigial, apparent only medially (Figs 42–43). Abdominal spiracles II and V–VII situated ventrally ( Figs 36–37 ), spiracles III and IV dorsally on the respective hypopleurites ( Figs 38 , 43: white arrows).

Hypopleurites (= outer laterotergites) well developed, their lateral margins forming continual outline, their posterior margins slightly convex (Fig. 40). Separate, narrow epipleurites (= inner laterotergites) are present in segments III− VI ( Fig. 38 ), invaginated in the fold between tergites (= mediotergites) and hypopleurites.

Sternite II narrow but completely developed ( Figs 46–47 ). Sternite III triangularly produced anteromedially ( Figs 36 , 46–48 ), with one large rounded tubercle posteromedially, carrying 3+3 trichobothria approaching midline, one triad on each side ( Figs 36–37 , 46–48 , 52 ); trichobothria on each side arranged triangularly, situated approximately at level of spiracles ( Figs 36 , 52 ). Sternites IV–VII with following arrangement of trichobothria on each side of body: Sternite IV with three trichobothria in one oval field submedially, in slightly prespiracular position, forming triangle (inner trichobothrium placed more posteriorly than lateral ones) ( Figs 36 , 52 ). Sternite V with three trichobothria laterally, anterior trichobothrium prespiracular, placed on large, rounded, prominent tubercle, two posterior ones postspiracular, placed on slightly elevated, oval field ( Figs 37 , 53 ). Sternite VI with three trichobothria laterally, anterior one prespiracular, placed on medium sized, apically excavated tubercle, two posterior ones postspiracular, placed on slightly elevated, oval field ( Figs 37 , 54 ). Sternite VII with two trichobothria laterally, both postspiracular ( Figs 37 , 55 ). Posterior portion of sternite VIII in male exposed below genital capsule ( Figs 36 , 57 , 74–75 ). Sternites III–VII shallowly sulcate sublaterally (especially on V–VII), lateral margins forming ventral portion of connexivum ( Figs 36–37 , 44–46).

► Figs 39–44. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs, abdomen. 39 – male, dorsal view (magnification 50×); 40–43 – female, dorsal view (40 – 42×; 41 – anteriorly, 55×; 42 – anterolaterally, 90×; 43 – detail of hypopleurites III and IV, 150×); 44 – female, lateral view (55×). Scale bars: 0.5 mm (Figs 41–43), 1 mm (Figs 39, 40, 44). (SEM micrographs by P. Kment).

Male genitalia. Genital capsule ( Figs 57–58 ) small, subquadrate, widest subapically; posterior aperture ( Fig. 58 ) large, divided by one narrowly triangular projection on each side into a broadly oval dorsal sinus and transverse, narrowly reniform ventral sinus. Paramere ( Figs 65–66 ) narrowly rhombic. Phallus as in Figs 67–69 (not inflated), aedeagus composed by a basal vestibule (TSAI & RÉDEI in press; = distinconjunctiva sensu BONHAG & WICK 1953) untraceable in repose, a narrow, helicoid complex forming two coils, and a thin penisfilum protruding from the complex, forming five coils.

Female genitalia with ensiform but relatively short ovipositor ( Figs 59–64 ); sternite VII completely bisected along midline, the two hemisternites broadly subtriangular, their posteromesal angles roundedly protruding, distal margins emarginate; valvifer IX nearly completely covered, only distalmost extremity exposed in rest ( Fig. 60 ). Spermatheca helical, apically widened ( Fig. 70 ).

Sexual dimorphism. Females somewhat wider and more robust than males (see the species description, measurements and calculated ratios), having wider abdomen compared with total body length, wider corium and pronotum compared with their lengths.

Differential diagnosis and systematic placement. Rhyparoclava gen. nov. is established here for a single species, R. pyrrhocoroides sp. nov., which is easy to distinguish from all known members of Rhyparochromidae due to its unique habitus, including anocellate head with prominent antenniferous tubercles, explanate lateral margins of pronotum and corium, brachyptery, and especially antennal segments II–IV forming a compact club, a condition unknown in any other member of the family. There are several genera with more or less incrassate antennal segments II to IV, e.g. Appolonius Distant, 1901 (Drymini) ( CHOPRA & SINGAL 1982), Lanchnophorus Reuter, 1887 (Rhyparochromini) ( KMENT et al. 2016), Longinischus Brailovsky, 2009 (Ozophorini) ( BRAILOVSKY 2009, BRAILOVSKY & BARRERA 2016), and Ptochiomera Say, 1832 (Myodochini) ( HENRY et al. 2015), but all of them have antennal segments attenuated both basally and apically so the antenna keeps its moniliform structure.

Although Rhyparoclava pyrrhocoroides gen. & sp. nov. somewhat resembles some members of Pyrrhocoroidea in its general habitus and the lack of ocelli, it certainly does not belong to Pyrrhocoroidea because of the following characters: 1) presence of epipleurites (inner laterotergites), and 2) presence of a sclerotized holder and a multicoiled penisfilum (unknown in any Pyrrhocoroidea). These two characters are synapomorphies of Rhyparochromidae (both Plinthisini and Rhyparochromini ), therefore the new genus is placed into this family. The lack of ocelli (a synapomorphy of Pyrrhocoroidea) in Rhyparoclava gen. nov. is therefore an autapomorphy evolved convergently and independently from the condition found in Pyrrhocoroidea, probably as a result of loss of the flight capacity in Rhyparoclava .

Based on the intersegmental suture between abdominal sternites IV and V curving anteriorly, terminating before attaining lateral abdominal margin ( Figs 36–37 , 44), the new genus is placed into the subfamily Rhyparochrominae ( SWEET 1967, HENRY 1997).

Following the keys to the tribes of Rhyparochrominae ( SWEET 1967, PÉRICART 1999a), the combination of the abdominal spiracle II positioned ventrally and spiracles III and IV positioned dorsally on hypopleurites (Fig. 43), the posterior pair of trichobothria on sternite V being always with one above the other ( Figs 37 , 54 ), and the anterior dorso-abdominal scent gland present between terga III and IV ( Fig. 49 ) unequivocally place Rhyparoclava to either Megalonotini or Rhyparochromini . Despite a superficial similarity of Rhyparoclava to some of the Gonianotini with explanate lateral margins of pronotum (especially Emblethis Fieber, 1860 – cf. PÉRICART 1999a,b), its placement in Gonianotini is excluded by the abdominal spiracle III positioned dorsally (it is positioned ventrally in Gonianotini ). However, a placement of Rhyparoclava to either Megalonotini or Rhyparochromini is problematic due to the fact that both tribes are best distinguished based on larval characters, which are not available for Rhyparoclava . The tribe Megalonotini is defined by the absence of a Y-suture between tergites III and IV in larva; the abdomen of the larva is black and heavily sclerotized; and anterior dorso-abdominal scent gland usually reduced, while in the larvae of Rhyparochromini , the Y-suture between tergites III and IV is present; the abdomen is usually light-pigmented, not black, and the anterior dorso-abdominal scent gland is always well developed ( SWEET 1967, PÉRICART 1999a). PÉRICART (1999a) added one more character in the key for West Palaearctic genera: pronotum without or with only a narrow lateral keel in Megalonotini (e.g. Sphragisticus Stål, 1872 ), while lateral margins of pronotum are largely lamellate in all their length in Rhyparochromini . However, this is true only for West Palaearctic Rhyparochromini genera, e.g. in the Indian Altomarus Distant, 1903 or Caridops Bergroth, 1894 , the lateral margin of pronotum is ecarinate, rounded (see DISTANT 1904). The presence of the vestiges of the anterior dorso-abdominal scent gland and the laterally explanate pronotal margin suggests an inclusion of Rhyparoclava into Rhyparochromini . However, a definitive tribal placement of the new genus requires either the discovery and description of a larva or the use of molecular phylogenetic methods in future studies.

The function of the peculiar clavate antennae ( Figs 1–2 , 11–12 , 35 , 71 ) of Rhyparoclava remains unknown. At first glance, they resemble antennae of some Clavigeritae ( Coleoptera : Staphylinidae : Pselaphinae ), e.g. Colilodion Besuchet, 1991 from Borneo and Sumatra (BE- SUCHET 1991: 501), or the recently descibed Squamiger elegans Hlaváč & Baňař, 2016 from central Madagascar ( HLAVÁČ & BAŇAŘ 2016: 394). The subtribe Clavigeritae contains strictly myrmecophilous genera (e.g. HLAVÁČ et al. 2013), having antennae strongly specialized for secretion of liquid compounds. However, we did not find any special morphological feature on antennae of Rhyparoclava such as gland openings ( Figs 12–15 , 71 ). The hard incrustation (slimy after softening in water) apparent on apical antennal segments in some specimens ( Figs 13, 14 ) is interpreted as contamination, not a secretion of the antennal segments. Just speculatively, the antennae may be involved in visual communication (cf. also WAPPLER et al. 2015) or may serve as a fat storage organ helping to survive in adverse environmental conditions.

Etymology. The generic name is composed from the Latinized Greek word rhyparo- (originally ρυπαρός, meaning dirty or filthy), standing here for the family Rhyparochromidae , and the Latin noun clava (meaning maul, stick, cudgel or club), referring to the unusual clavate shape of antennae, unique within the family. The gender is feminine.

Figures

Figs 1–2. Rhyparoclava pyrrhocoroides gen. & sp. nov., habitus. 1 – female, dorsal view; 2 – male, ventral view. (Photographs by P. Kment).

Figs 3–8.Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs:3 – habitus, dorsal view (18×); 4–5 – head and pronotum (4 – dorsal view, magnification 60×; 5 – ventral view,75×); 6–8 – head (6 – dorsal view, 95×; 7 – ventral view, 95×; 8 – lateral view, 110×). Scale bars: 0.5 mm (Figs 4–8), 1 mm (Fig. 3). (SEM micrographs by P. Kment).

Figs 9–15. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs: 9–10 – scape (= antennal segment I) (9 – dorsal view, magnification 200×; 10 – ventral view, 210×); 11 – antennal segments II–IV, dorsal view (70×); 12–13 – basiflagellum (III) and distiflagellum (IV) (12 – dorsal view, 110×; 13 – ventral view, with film formed by slimy secretion, 130×); 14–15 – basiflagellum, dorsal view, microsculpture (14 – with slimy secretion, 400×; 15 – 850×). Scale bars: 50 μm (Fig. 15), 0.1 mm (Fig. 14), 0.2 mm (Figs 9–10), 0.4 mm (Fig. 13), 0.5 mm (Figs 11–12). (SEM micrographs by P. Kment).

Figs 35–38. Rhyparoclava pyrrhocoroides gen. & sp. nov.: 35 – antenna; 36–38 – abdomen (36 – ventral view, 37 – lateral view, 38 – dorsal view). Scale bars: 1 mm. (Line drawings by V. Hemala). Abbreviations: e ‒ epipleurite; h ‒ hypopleurite; t ‒ tergite.

Figs 65–71. Rhyparoclava pyrrhocoroides gen. & sp. nov., male and female genitalia: 65–66 – paramere (two different views); 67–69 – phallus, not inflated (67 – ventral, 68 – lateral, 69 – dorsal view); 70 – spermatheca; 71 – basi- and distiflagellum after KOH treatment. Scale bars: 0.1 mm (65–70), 0.5 mm (71). (Photographs by P. Baňař).

Figs 23–28. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs: 23 – meso- and metathorax, ventral view (magnification 75×); 24 – metasternum, ventral view (400×); 25–27 – external scent efferent system of the metathoracic scent gland (25 – ventrolateral view, 130×; 26 – ventrolateral view, 190×; 27 – ventral view, 170×); 28 – peritreme, ventral view (300×). Scale bars: 0.1 mm (Figs 24, 28), 0.3 mm (Figs 26, 27), 0.4 mm (Fig. 25), 0.5 mm (Fig. 23). (SEM micrographs by P. Kment).

Figs 29–34. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs: 29 – profemur, ventral view, detail of anteroapical spines (magnification 600×); 30 – apex of protibia and protarsus (200×); 31 – apex of protibia, detail (500×); 32 – metatarsus, dorsal view (210×); 33–34 – propretarsus (33 – apical view, 700×; 34 – ventrolateral view, 550×). Scale bars: 50 μm (Figs 29, 33), 0.1 mm (Figs 31, 34), 0.2 mm (Figs 30, 32). (SEM micrographs by P.Kment).

Figs 74–78. Rhyparoclava pyrrhocoroides gen. & sp. nov., wart-like tubercles (marked by white arrows), SEM micrographs. 74 – thorax and abdomen, male, ventral view (45×); 75 – abdomen, male, lateral view (65×); 76 – scapes, ventral view (120×); 77 – scutellum and hemelytron, dorsal view (75×); 78 – metapleuron with ostiole and peritreme, ventrolateral view (250×). Scale bars: 0.5 mm (74–77), 0.1 mm (78). (SEM micrographs by P. Baňař).

Figs 45–51. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs, abdomen: 45 – male, ventral view (magnification 47×); 46 – female, ventral view (42×); 47 – female, detail of anterior region (70×); 48 – male, details of sternites II–IV (70×). 49–51 – female, scars of larval dorso-abdominal scent glands, dorsal view: 49 – tergites III and IV; 50 – tergites IV and V (300×); 51 – tergites V and VI (300×). Scale bars: 0.1 mm (Fig. 49), 0.2 mm (Figs 50–51), 0.5 mm (Fig. 48), 1 mm (Figs 45–47). (SEM micrographs by P. Kment).

Figs 52–58. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs.52–55 – details of trichobothria in ventral view (52 – sternites III and IV, magnification 270×; 53 – segment V, 190×; 54 – segment VI, 190×; 55 – segment VII, 190×); 56 – segment VIII, dorsal view (200×); 57 – sternite VIII and genital capsule, ventral view (210×); 58 – genital capsule, dorsal view (170×). Scale bars: 0.2 mm (Figs 52, 56–57), 0.3 mm (Figs 53–55, 58). (SEM micrographs by P. Kment).

Figs 59–64. Rhyparoclava pyrrhocoroides gen. & sp. nov., SEM micrographs. 59–61 – female terminalia, ventral view (59 – 95×, 60 – 140×, 61 – 300×). 62–64 – ovipositor (62 – ventral view, 90×, 63 – detail in ventral view, 180×, 64 – detail in lateral view, 160×). Scale bars: 0.1 mm (Fig. 61), 0.3 mm (Figs 59–60, 63–64), 0.5 mm (Fig. 62). (SEM micrographs by P. Kment).