Dichelocentrum, Gapon, 2014

Gapon, D. A., 2014, Revision of the genus Polymerus (Heteroptera: Miridae) in the Eastern Hemisphere. Part 1: Subgenera Polymerus, Pachycentrum subgen. nov. and new genus Dichelocentrum gen. nov., Zootaxa 3787 (1), pp. 1-87 : 68-73

Genus Dichelocentrum gen. nov.

Type species: Dichelocentrum transvaalicum sp. nov.

Diagnosis. Recognised by anterior spicule divided into two branches, posterior branch of baso-apical sclerotised band strongly dilated in distal part, and following combination of characters: short, not strongly pointed preocular part of head; pale spots on frons reaching antennal cavities anteriorly (vs. not reaching in dark species of Polymerus ); thickened second antennal segment in males, greater in its diameter than collar width ( Fig 33 H ); narrow pronotal collar; fine punctures on pronotum; body covered with adpressed, weakly widened gold or silver setae; claws without tooth; right paramere long, completely sclerotised (except for weakly sclerotised anterior wall of body) with rather long and wide, curved anteriad hypophysis (as opposed to the same in Polymerus and Charagochilus ); vesica with small left anterior and posterior lobes; swollen anterior right lobe with only low bladders; medial right lobe, medial and posterior spicules, left serrate carina, posterior bladder and fields of microtrichia on vesica absent; rather short posterior right lobe subdivided into two branches; branched baso-apical sclerotised band with posterior branch reaching posterior apex of vesica; secondary gonopore located on left wall of vesica, with complete ring of subequal concentrically curved spinulae; two pairs of anterior and posterior vestibular sclerite connected together; presence of dorsal sac, inner horizontal fold and medial process in gynatrium; ring sclerites without triangular plates on external margins; and absence of transverse fold, dorsal structure, lateral lobes and medial lobe.

Description. Size and shape of body ( Fig. 42 ). Body rather small, 4.10–5.00 in males and 4.35–5.80 in females, elongate-oval with sub-parallel lateral margins, slightly convex dorsally.

Colouration. Dorsal surface of head yellowish brown to dark brown, with large pale spots along inner margins of eyes, reach antennal fossae and dilated posteriad. Dorsal surface of head can be almost entirely pale ( D. transvaalicum sp. nov.). Ventral surface of head and mandibular plates light. Antennae at least partially pale. Pronotum dark brown or blackish, its posterior margin with brownish-yellow stripe, not reaching to lateral angles. Ends of this stripe slightly extended in form of triangular patches directed anteriad. Pronotum of D. longirostre ( Reuter, 1905) comb. nov. usually with narrow longitudinal light strip; pronotum of some specimens of D. transvaalicum pale, with a few large dark spots. Collar yellowish-brown, rarely dark. Pleurites yellowish brown or dark brown, propleurites pale, their posterior margins and margins of coxal cavity yellowish. Evaporatorium yellowish or whitish. Scutellum dark brown, with yellow spot at apex, ranging in size from small to very large. Femora, tibiae and tarsi pale. Femora often with small or large dark brown spots, rarely almost entirely dark brown. Third tarsal segment dark. Bristles on tibiae dark brown. Clavus dark brown, with paler anterior and posterior corners. Corium yellowish-brown, with more or less large dark spots in posterior and internal parts. Sometimes corium almost entirely dark brown, except for narrow strip along external margin. Small longitudinal spot on corium behind apex of clavus yellowish. Cuneus often light brown, dark brown or russet. It usually reddish in D. ornatifrons (Odhiambo, 1959) comb. nov. and D. flora ( Linnavuori & van Harten, 2005) comb. nov. Base and apex of clavus yellowish. Ventral surface of abdomen light brown, sometimes dark brown or reddish with brownyellowish spots and narrow dark stripe on each side along lateral margins.

Surface and vestiture. Pronotum densely covered with very small and shallow punctures. Surface between them smooth and shiny. Area around calli matte. Scutellum without punctures, with very fine transverse wrinkles, less shiny than pronotum. Clavus and corium with subtle sparse punctures, matte. Body entirely covered with thin, slightly raised, gray setae; head, thorax, wings and abdomen venter also covered with weakly thickened, easily deciduous silvery or goldish setae.

Structure of body. Head transverse, oblique, with short preocular part. Frons more or less convex, vertex flat, its posterior margin with distinct carina along entire width. Clypeus not protruding beyond anterior margin of frons. Eyes large, vertical in lateral view and transverse in dorsal view. Mandibular plates triangular, maxillar plates subquadrangular with oblique anterior margin. Buccula short. Rostrum reaches hind coxae or slightly protrudes beyond them; its first segment reaches middle of xyphus of prothorax. Antennal fossa located close to inferior margin of eye. First segment slightly thickened, several times shorter than second, slightly shorter than third and fourth ones separately. Second antennal segment in males about the same thickness as first segment and distinctly thicker than third and fourth segments ( Fig. 33H ). Second antennal segment in females significantly thinner than first segment, very slightly thickened apically, its base about the same thickness as third and fourth segments.

Pronotum trapezoidal, more or less convex in posterior part and slanted anteriad. Cali rather large, strongly flattened. Anterior margin of pronotum slightly concave, with collar. Its width approximately equal to diameter of female second antennal segment in its middle. Lateral margins of pronotum straight, smooth, posterior margin straight in middle, with rounded lateral parts. Anterior and posterior angles of pronotum rounded. Xyphus of prothorax with round carinae on its margins. Mesoscutum partly exposed, looking as narrow transverse strip in front of scutellum base. Scutellum approximately as long as wide, its surface more or less convex. Hemelytra macropterous or subrachypterous, their lateral margins nearly straight in males and more convex in females. Membrane brown, with whitish small patches near apex of cuneus. Openings of metathoracic scent glands small, continuing as short ruga surrounded by small evaporatory area, expanding posteriorly. Femora slightly bent, flattened laterally. Tibiae cylindrical, straight. First segment of all tarsi shorter than second one, second and third segments subequal in length.

Genital capsule conical, rounded posteriorly, without any prominences. Posterior opening of genital capsule subsymmetrical, extending anteriad and narrowing in posterior part. Two paramere sockets located in its posterior corners. Cuplike sclerite of genital chamber large, ovoid, narrowing anteriad. Proctiger as in Polymerus .

Right paramere ( Figs 34 , 35 : A, B, E, F, I, J) long, subcylindrical, slightly shorter then left one. Paramere body without processes and protrusions. Anterior wall of body straight in apical part and slightly concave in basal part, rather weakly sclerotised but not hyaline; posterior wall strongly sclerotised, convex in basal part. Hypophysis rather short, curved anteriad, its left (internal) margin skewed downwards.

Left paramere ( Figs 34 , 35 : C, D, G, H, K, L). Anterior wall of paramere body from lateral view slightly and evenly convex or almost straight, posterior wall strongly, subrectangular convex basally. Sensory process located on left (external) wall of body, short and broad. Hypophysis long, curved anteriad, flattened laterally, expanding distally from lateral view, with acicular extreme apex, slightly curved to right. Right (internal) wall of hypophysis with more or less high carina. The latter with row of thin setae in some species.

Aedeagus. Phallobase as in Polymerus .

Basal part of theca with membranous lateral and posterior walls, apical part of theca and its anterior wall basally sclerotised. Apical part of anterior wall weakly sclerotised. Apical margin of theca with single triangular anterior sclerotised blade. Its apex with small notch on left side ( Fig. 5 C ). This blade turns forward during copulation.

Vesica ( Figs 13 F ; 36 ; 37 ) relatively small and consists of anterior and posterior membranous parts, separated with depressions on right and left sides of vesica. Long basi-apical sclerotised band located in right depression, secondary gonopore lies in left one. Secondary gonopore small, ovate, with complete ring of subequal, concentrically curved spinulae ( Fig. 13 F ). Anterior part of vesica with two lobes. Right anterior lobe swollen moderately long and wide, with anterior branch and three wide bladders. Anterior branch directed anteriad, slightly downwards and to right. Superior bladder more convex, right one flattened, inferior bladder as superior or as right ones. Anterior spicule lies on posterior walls of lobe base and its superior bladder. Basal part of this spicule wide and being continuation of anterior branch of baso-apical sclerotised band. In distal part anterior spicule bifurcates into two branches directed anteriad and slightly to left. These branches subequal in length and curved downwards apically. Anterior branch with more sharply curved apex, posterior one slightly wider than the latter and curved more gradually. Anterior left lobe rather small, broad in basal part, tapering apically, with two branches. Superior branch directed upwards and curved posteriad in apical part; inferior branch usually shorter, directed downwards and anteriad. Posterior part of vesica slightly smaller than anterior one, with posterior apex directed posteriad, and with two lobes. Posterior left lobe of the same size as anterior left one, not branched, directed to left and its apex touches the latter. Base of lobe often with smooth basal tubercle. Both left lobes cover secondary gonopore on each side and superiorly, forming short channel. Medial right lobe, medial left tubercle and medial spicule absent. Posterior right lobe rather narrow, longer than other lobes of vesica, directed anteriad and divided into two branches in distal part. Posterior branch of baso-apical sclerotised band curved to left on superior surface of posterior part of vesica and reaches its apex. This branch greatly widened and covered with longitudinal rugae in middle, tapering distad. Posterior wall of vesica weakly sclerotised in extreme base.

Gynatrium ( Figs 38 ; 39 ). Dorsal labiate plate usually with very thin sclerotised band connecting ring sclerites. Dorsal sac rather large, with rather thickened walls and wide rounded anterior margin. Its length is approximately equal to width; it overlies tectal sclerites but not covering its external parts. Tectal sclerites separate and looks like pair of triangular plates with sharp internal angles directed mediad. Posterior margins of tectal sclerites form short rounded prominences. Inner horizontal fold rather long. Transverse fold absent. Medial lobe on posterior margin of gynatrial roof absent. Interramal sclerites large, merged into single sclerite. Its lateral angles strongly elongated, external margins slightly convex in middle, ventral margin with more or less deep notch, dorsal margin smooth concave, without medial prominence. Anterior walls of interramal lobes membranous, only dorsal margins of their openings bordered by narrow sclerotised edging connected with lateral angles of interramal sclerites. Medialprocess small, round, lie in middle of interramal sclerite. Anterior vestibular sclerites small, diverging anteriorly, parallel in posterior part, lie in parasagittal plane on internal walls of folds formed by membrane connecting first gonocoxites. Posterior vestibular sclerites lie in frontal plane, very large, boomerang-shaped, with closely spaced parallel anterior ends and divergent posterior ones. Ends of anterior and posterior sclerites of each pair connected to one another.

Measurements of all species of the genus are given in Table 4 .

Distribution. Afrotropic: Yemen, Eastern, Western and Southern Africa

Etymology. Name of the genus derived from the ancient Greek words “διχηλός”, bifurcated and “κέντρον”, needle, spine, spike. The gender of the name is neuter.

Key to species of genus Dichelocentrum gen. nov.

1(2). Femora and the first antennal segment ( Fig. 33 A ) yellowish or brownish-yellow, without dark spots, or first antennal segment with small isolated dark spot on external surface. Right paramere with short and tapering hypophysis on lateral view and small smooth tubercle on anterior wall under it ( Fig. 34 A, E ). Left paramere with long hypophysis, its superior and inferior margins convex before apex on lateral view ( Fig. 34 C, G ). Superior margin of posterior branch of spicule of vesica smoothly curved ( Fig. 36 A )............................................................................. 1. D. longirostre

2(1). Femora with small or large dark spots or distinctly reddish. First antennal segment with short or long dark ring at base, or first segment in most part or entirely black or red ( Fig. 33 B–E ).

3(4). First two antennal segments, femora and venter of abdomen reddish ( Fig. 42 C ). Right paramere with short and tapering hypophysis on lateral view and small smooth tubercle on anterior wall of body under hypophysis ( Fig. 34 I ). Left paramere with long hypophysis, its superior and inferior margins convex before apex on lateral view ( Fig. 34 K ). Superior margin of posterior branch of vesical anterior spicule sharply curved ( Fig. 36 B, C )......................................... 2. D. flora

4(3). Antennae, femora and venter of abdomen not red. Superior margin of posterior branch of vesical anterior spicule smoothly curved ( Fig. 36 D ).

6(9). Smaller, length 3.95–5.00. Body usually with large pale spots ( Fig 42 E, G, H ). Right paramere with rather long and wide hypophysis on lateral view (35 A, I). Africa.

7(8). Head pale or dark superiorly. Pronotum with several large dark spots, if it completely dark, than with light longitudinal stripe visible at least in posterior part ( Fig. 42 G, H ). Veins of membrane not red. Inferior margin of left paramere hypophysis convex in middle and concave before apex ( Fig. 35 K )....................................... 4. D. transvaalicum sp. nov.

8(7). Superior surfaces of head and pronotum always dark, the latter without longitudinal pale stripe ( Fig. 42 D, E ). Veins on membrane often red. Inferior margin of left paramere hypophysis straight on all length ( Fig. 35 C, G ).......... 3. D. ornatifrons

9(6). Greater, length 5.00–5.80 mm. Body very dark ( Fig. 42 I ). Right paramere with rather short and narrow, pointed hypophysis on lateral view ( Fig. 35 M ). Arabian Peninsula.................................................... 5. D. alkadanum

Figures

FIGURE 5. Structure of theca. A, theca of Polymerus nigrita; B, theca of Dichelocentrum longirostre; C, apical blade of theca of Dichelocentrum longirostre; D, apical blade of theca of Charagochilus gyllenhalii. Anterior (A, B) and anterio-inferior view (C, D). Scale bare: 0.14 mm.

FIGURE 13. Secondary gonopore. A, Polymerus (Pachycentrum) nigrita; B, P. (Poeciloscytus) unifasciatus; C, Charagochilus gyllenhalii; D, Proboscidocoris fuliginosus; E, Pr. nitidus; F, Dichelocentrum longirostre. lsc—left serrate carina; sgp—subgonoporal plate.

FIGURE 33. Antennae. A–E, first antennal segment; F–H, antennae totally. A, Dichelocentrum longirostre comb. nov., syntype; B, D. ornatifrons comb. nov. from Tanzania; C, holotype of Polymerus xerophilus; D, D. ornatifrons, male paratype; E, D. ornatifrons, female paratype; F, Polymerus carpathicus, male; G, D. transvaalicum sp. nov., female; H, D. transvaalicum, male. Scale bare: 0.14 mm.

FIGURE 34. Parameres of Dichelocentrum gen. nov. species. Right (A, B, E, F, I, J) and left (C, D, G, H, K, L) parameres. A–D, D. longirostre comb. nov., syntype; E–H, D. longirostre comb. nov. from Tanzania; I–L, D. flora comb. nov. Right (A, E, I), left (C, G, K) and posterior (B, D, F, H, J, L) view. Scale bare: 0.14 mm.

FIGURE 35. Parameres of Dichelocentrum gen. nov. species. Right (A, B, E, F, I, J, M, N) and left (C, D, G, H, K, L, O) parameres. A–D, D. ornatifrons comb. nov., paratype; E–H, D. ornatifrons from Tanzania; I–L, D. transvaalicum sp. nov.; M–O, D. alkadanum comb. nov. after Linnavuori & van Harten (2005). Right (A, E, I, M), left (C, G, K, O) and posterior (D, B, F, H, J, L, N) view. Scale bare: 0.14 mm.

FIGURE 36. Vesica of Dichelocentrum gen. nov. A–C, uninflated vesica; D–H, anterior spicule; I–K, inflated vesica. A, D. flora comb. nov., holotype; B, D. ornatifrons comb. nov., paratype; C, D. alkadanum comb. nov., paratype after Linnavuori & van Harten (2005); D, D. longirostre comb. nov., syntype; E, D. flora, holotype; F, D. flora from Niger; G, D. ornatifrons, paratype; H, D. alkadanum, paratype after Linnavuori & van Harten (2005); I, J, D. longirostre; K, D. flora. Left (A–C, I), posterior (D–H), and superior (J, K) view. all—anterior left lobe; arl—anterior right lobe; as—anterior spicule; pa—posterior apex of vesica; pb.bab—posterior branch of basoapical sclerotised band; pll—posterior left lobe; prl—posterior right lobe; sg—secondary gonopore. Scale bare: 0.14 mm.

FIGURE 37. Vesica of Dichelocentrum gen. nov. A–C, D. ornatifrons comb. nov.; D, E, D. transvaalicum sp. nov. Left (A, D), superior (B, E) and posterior (C) view. Scale bare: 0.14 mm.

FIGURE 38. Inner female genitalia of Dichelocentrum gen. nov. A, gynatrium in dorsal view; B, C, posterior wall of gynatrium in ventral view. A, B, D. longirostre comb. nov., syntype; C, D. ornatifrons comb. nov. mpr—medial process; ihf—posterior margin of inner horizontal fold; ts—tectal sclerites.. Scale bare: 0.14 mm.

FIGURE 39. Inner female genitalia of Dichelocentrum gen. nov. A, gynatrium in dorsal view; B, D, posterior wall of gynatrium in ventral view; C, vestibular sclerites in dorsal view. A–C, D. transvaalicum sp. nov.; D, D. alkadanum, paratype. avs—anterior vestibular sclerites; ihf—posterior margin of inner horizontal fold; mpr—medial process; pvs— posterior vestibular sclerites; ts—tectal sclerites. Scale bare: 0.14 mm.

FIGURE 42. Dichelocentrum gen. nov., habitus. A, D. longirostre comb. nov., syntype, male; B, D. longirostre comb. nov., female; C, D. flora comb. nov., holotype, male; D, D. ornatifrons comb. nov., paratype, male; E, D. ornatifrons, paratype, female; F, holotype of Polymerus xerophilus, female; G, D. transvaalicum sp. nov., male; H, D. transvaalicum, female; I, D. alkadanum comb. nov., holotype, female.