Ploiaria anak Distant, 1909

Pansare, Pratik P., Ghate, Hemant V. & Webb, Mick, 2018, Redescription of the thread-legged assassin bug Ploiaria anak (Hemiptera: Heteroptera: Reduviidae: Emesinae) from India, with notes on its biology, Zootaxa 4388 (4), pp. 557-566 : 558-565

Ploiaria anak Distant, 1909

Ploearia anak Distant, 1909: 505 . Syntype (s): India, Lucknow ; BMNH (examined).

Ploearia anak: Distant (1910: 180, Fig. 99) (redescription, figure).

Ploiaria anak: Wygodzinsky (1966: 165, 168) (in key, records, distribution), Maldonado Capriles (1995: 109) (catalogue), Ambrose (2006: 2396, supplement 5) (checklist), Rédei (2008: 15) (in key).

Type material examined. Lectotype (here designated): male, [India, Uttar Pradesh:], “Aitken / Lucknow”, “ Ploearia / anak / Type Dist.”, “Distant Coll. / B.M.1911-383”, “Type” [disc with red margin] ( Fig. 24 ). Paralectotype: female, with similar locality and collection label ( Fig. 25 ). Both specimens are deposited in BMNH.

Additional specimens examined. India: Pune District, Daund, vi.2016, leg. P. Pansare (1 female, Modern College of Arts, Science & Commerce, Shivajinagar, Pune); same but viii.2016 (1 female, same depository); one male and one female from the same locality but xii.2016, found trapped in spider web (1 male and 1 female, same depository).

Redescription. Female. Colouration: Ground colour of body pale ochraceous, with a pattern of pale brown to dark brown longitudinal bands or patches on head, thorax, legs and abdomen dorsally and laterally. Ventral colouration mostly pale on head and thorax. Fore legs ochraceous, with brown patches on coxa and femur, not extending to ventral side; tarsus pale except extreme apex; spiniform processes of anteroventral row on fore femur completely black including their bases, those of posteroventral row pale with only a narrow black ring at base, set on a pale brown base; mid and hind legs uniformly brownish except femoro-tibial articulations which are pale, femora darker than corresponding tibiae, tarsi very pale. Abdomen dorsally and ventrally partly reddish, with brown patches on tergites; connexivum pale with some brown patches; longitudinal brownish bands present ventrally beyond middle.

Anteocular part of head with a pair of dark lateral bands with black tubercles, median area with colourless fine granules, eyes dark black. Antennae dark brown, base and apex of segment I pale, segment II darker except pale apex, segments III and IV pale. Postocular part of head with a median ochraceous band and lateral brownish areas with dark tubercles. Head beneath pale, smooth and shining. Labium with second visible segment laterally brown, third visible segment pale brown.

Pronotum with a broad, median, ochraceous band, lateral area pale brown with dark brown granules at few places; with a pair of ochraceous spots laterally on each side near anterior margin; prosternum pale cream with a few brown specks laterally and in front of fore coxae. Meso- and metanota with thin, median ochraceous line and one broad line of similar colour on either side, rest area dark brown. Mesosternum pale cream; metasternum (and some part just anterior to mid coxae) pale brown, with median carina.

Structure: Head ( Figs. 5–6 , 8 ) elongate oval, both anteocular and postocular parts distinctly tumescent dorsally, rounded laterally, granulate. Antenniferous tubercles situated dorsally; clypeus and mandibular plates sloping anteriad and projecting beyond antenniferous tubercles, clypeus slightly more prominent than mandibular plates. Clypeus and mandibular plates finely granular, granules on disc of anteocular area small and colourless, those on lateral area coarser and darker. Transverse interocular sulcus prominent, eyes large. Posteriormost part of head forming a short, almost parallel-sided neck. Antennae thin and long, first and second joints subequal in length, third and fourth considerably shorter. Ventral surface of head smooth and shining. Labium with first two visible segments moderately swollen, third visible segment narrowed, slightly curved, sharp at tip ( Fig. 8 ), extending up to base of fore coxae, resting on prosternal groove which has fine transverse stria.

Thorax ( Figs. 5–6 , 9–10 ): Pronotum broad anteriorly, gradually narrowed posteriorly, posterior fourth almost parallel-sided, median area very finely, lateral part more coarsely granulate. Anterior margin straight behind head, anterior corner slightly elevated and rounded. Mesonotum narrowed anteriorly, gradually dilated posteriorly, dorsomedian part finely granulate, with a fine median sulcus which is distinct in posterior third of segment. Dorsolateral part demarcated by a distinct carina or raised margin along its entire length, area laterad to this carina with large granules. Metanotum subquadrate with fine median longitudinal sulcus, finely granulate dorsomedially, lateral area with larger granules ( Figs. 9–10 ). Pro- and mesosterna medially almost smooth, shining, with very scattered fine granules; metasternum medially finely granulate and with a distinct carina between mid and hind coxae; mid and hind coxae oblong, shining and smooth. Prothoracic acetabula directed forward; hind coxae closer to each other than mid coxae.

Legs: Fore legs ( Figs. 6–7 , 11 ) robust. Fore coxae moderately long, shorter than fore femur, unarmed; fore trochanter thick, armed with a long process (4–5 times as long as its width at base) provided with a small apical spine and also with a very small spine on its inner face. Fore femur slightly broader in proximal half than distally, longer than coxae, with an anteroventral and a posteroventral row of spiniform processes; posteroventral row with about 6 longer, elevated and several minute, wart-like processes, each with a short apical spine ( Fig. 11 ). Fore tibia shorter than fore femur, more or less straight, its apical portion slightly dilated and bent, with few small setae and fine tubercles in proximal half and short spiniform processes in distal half, apex with a tuft of stiff setae ventrally; tarsus three-segmented, segment I longest, segment III shortest.

Abdomen ( Figs. 5 , 12–15 ) with basal fifth narrow and parallel-sided, beyond which laterally dilated, broadly oval and dorsally convex, and again narrowed towards posterior tip; abdomen six times broader at its widest place than basally. Segment I with lateral angular projection on either side; segment II gradually dilated posteriorly; segments III–V successively broader, again narrowed from segment VI onwards. Entire dorsal surface very finely granulate, ventral surface finely granulate and sculptured; ventral intersegmental sutures indistinct; spiracles very small, situated on ventral laterotergites, surrounded by fine white border ( Fig 12 , 14 ).

Female terminalia as in Figs. 13–14 .

Male. Colouration. Colour only slightly different to female, especially ventrally (see Figs 16–17 ).

Structure. Abdomen slightly narrower than in female ( Figs. 16–17 ).

Male terminalia. Pygophore 0.8 mm long, slightly elongate oval, moderately sclerotized, ventrally distinctly convex, dorsally flat, with a sharp posterosuperior spine preceded by rounded protuberance; with a pair of small spines, directed vertically towards dorsum, situated laterally mesad to paramere, visible in dorsal ( Fig. 18 ) and lateral views ( Fig. 19 ); anterior (basal) opening oval in dorsal view, outline of phallus visible in lateral view, endosoma visible in ventral view ( Fig. 20 ) in macerated preparatums. Parameres symmetrical, widely separated, small, sock-like ( Fig. 23 ). Phallus ( Figs. 21–22 ) more or less similar to the condition found in Ploiaria huangorum Rédei & Tsai, 2010 .

Measurements (in mm; male / female). Total length 10.5 / 9.75, length of anteocular region of head 0.50 / 0.60, length of postocular region of head 0.43 / 0.50, width across eyes 0.63 / 0.60, interocular distance 0.35 / 0.30; length of first visible labial segment 0.35 / 0.30, length of second visible labial segment 0.38 / 0.40, length of third visible labial segment 0.38 / 0.40; maximum width of pronotum 0.65 / 0.68, width of pronotum at base of head 0.45 / 0.40, length of pronotum 1.35 / 1.40; length of mesonotum 1.13 / 1.00; length of metanotum 0.63 / 0.90; minimum width of abdomen (at base) 0.25 / 0.25, maximum width of abdomen (at middle) 1.75 / 1.65; fore leg: length of coxa 1.13 / 1.00, length of femur 2.55 / 2.35, length of tibia 1.75 / 1.60, length of tarsus with claw 0.75 / 0.65, length of first tarsal segment 0.28 / 0.31, length of second tarsal segment 0.23 / 0.25, length of third tarsal segment 0.38 / 0.35; mid leg: length of coxa 0.50 / 0.50, length of femur 7.70 / 6.50, length of tibia 10.0 / 8.50, length of tarsus 0.30 / 0.30; hind leg: length of coxa 0.50 / 0.50, length of femur 10.5 / 9.00, length of tibia 13.75 / 13.0, length of tarsus with claw 0.30 / 0.30; length of prosternum 1.50 / 1.50, length of mesosternum 1.10 / 1.20, length of metasternum 0.60 / 0.50; length of first antennal segment 6.75 / 6.00, length of second antennal segment 6.00 / 5.50, length of third antennal segment 0.75 / 0.80, length of fourth antennal segment 1.10 / 1.10.

Distribution. Pakistan: Punjab ( Wygodzinsky 1966); India: Uttar Pradesh ( Distant 1909), Tamil Nadu ( Ravichandran 1988, Ambrose 2006), Rajasthan: Mahwah, Gujarat: Godhra ( Wygodzinsky 1966), Maharashtra: Pune District (new record).

Remarks. P. anak was described from an unspecified number of specimens (syntypes) from ‘Lucknow (Aitken)’. A male and a female syntype ( Figs. 24, 25 ) are present in the BMNH, from which the male is selected as lectotype. Photo of an additional non-type male from the environs of Godhra, Gujarat, deposited in the CASC, identified and listed by Wygodzinsky (1966), has been examined as well ( Fig. 26 ). One male studied in detail was found dead, trapped in a spider web, and many parts of the body became detached during cleaning. Subsequently, in November 2017, a fresh live male was collected, and the measurements of male were taken from this individual.

Bionomics. Both live females of P. anak were observed moving slowly on the wall where small spiders were also detected. When brought to the laboratory, we observed that the bug could move on a spider web without getting entangled ( Fig. 1 ). Knowing that some emesine bugs feed on spiders ( Wygodzinsky 1966, Wignall & Taylor 2010, Soley et al. 2011) and Eugubinus araneus Distant (1904: 207) was reported “living in nest of spider”, we provided one of the females of P. anak females with a small moth, a small dipteran, a lygaeid and a mirid bug, and a small spider; within a short time the spider was aggressively caught and its content sucked. Two more spiders offered were treated similarly ( Fig. 2 ). This species is apparently a specialist predator of spiders. Nevertheless, we also found one male and one female of P. anak and a specimen of another emesine bug ( Stenolemus sp.) dead and trapped in spider web; this indicates that these emesines sometimes get trapped in spider webs ( Fig. 3 ).

The female collected in August 2016, with distended abdomen ( Figs. 4–5 ), was found to carry three large, nearly fully developed eggs, each about 1.5 mm long ( Fig. 15 , one egg removed). This indicates that the breeding season of this species is during July and August and that the female can deposit at least three eggs at a time.

Figures

FIGURES 24–26. Ploiaria anak Distant, 1909. Fig. 24, lectotype (male); Fig. 25, paralectotype (female); Fig. 26, a non-type male from Godhra, Gujarat, India, deposited in CASC, and its labels. Figs. 24–25 © BMNH, Figs. 26 © CASC.

FIGURES 1–7. Ploiaria anak Distant, 1909, from Daund, Pune. Fig. 1, living bug on small spider web; Fig. 2, a bug feeding on spider; Fig. 3, a bug trapped in a large spider web; Fig. 4, female, lateral view; Fig. 5, same, dorsal view; Fig. 6, same, details of anterior portion of body, lateral view; Fig. 7, same, details of fore femur, tibia and tarsus.

FIGURES 8–12. Ploiaria anak Distant, 1909, from Daund, Pune; SEM micrographs. Fig. 8, head, lateral view; Fig. 9, meso- and metanota; Fig. 10, same, higher magnification; Fig. 11, fore legs; Figs. 12, elevated spiracle (marked with red arrow)

FIGURES 13–17. Ploiaria anak Distant, 1909, from Daund, Pune; abdomen. Figs. 13–14, female terminalia in ventral and lateral views, respectively; Fig. 15, female abdomen cut open to reveal eggs; Figs. 16–17, male abdomen in dorsal and ventral views, respectively.

FIGURES 18–23. Ploiaria anak Distant, 1909, from Daund, Pune; male genitalia. Figs. 18–20, pygophore in dorsal, lateral and ventral views respectively; Fig. 21, phallus in lateral view; Fig. 22, details of endosoma; Fig. 23, parameres.