Caystrus trivalis (Gerstaecker)

Ahmad, I. & Zahid, M., 2009, Resurrections and redescriptions of Caystrus marginiventris (Stål), C. trivalis (Gerstaecker) and C. pseudobrunnescens Linnavuori (Hemiptera: Pentatomidae: Pentatominae), key to this complex and their cladistic relationships, Pakistan Journal of Zoology 41, No. 4, pp. 305-312 : 309-310

Caystrus trivalis (Gerstaecker)

( Figs. 3)

Anarropa trivalis Gerstaecker 1873: 398-399 p. 17 fig 1; Stål 1876: 70; Schouteden 1905: 13. Caystrus trivalis, Linnavuori 1972: 401 , 405- 6; figs. 5c-f; 1974: 402, 406; fig. 5d; 1982: 76, fig. 102 6b-d.

Colouration and general shape

Body light brown with thick brown punctures; eyes blackish brown; ocelli pinkish; membrane of hemelytra light brown.

Head

Distinctly broader than long; anteocular distance distinctly shorter than remainder of head; paraclypei broad, longer than clypeus, separated at tips, apices pointed, lateral margins sinuate, a round lobe adjacent to eyes present; antennae with basal segment reaching head apex, 2 nd segment shorter than 3 rd, 5 th longest, length of segments I 0.5 (0.5- 0.6), II 1.1 (0.75-1.1), III 1.35 (0.9-1.4), IV 1.7 (1.1- 1.7), V 1.85 (1.4-1.9), antennal formula I<2<3<4<5; labium just reaching hind coxae, 2 nd and 3 rd segments equal, length of segments I 0.75 (0.7-0.8), II 1.2 (1.0-1.4), III 1.2 (0.9-1.2), IV 0.9 (0.7-0.9), labial formula I<IV<2 = 3; anteocular distance 0.8 (0.8-0.9), remainder of head 1.1 (0.9-1.15); width of head 2.55 (2.25-2.6); interocular distance 1.4 (1.3- 1.5); interocellar distance 0.8 (0.8-0.9).

Thorax Pronotum slightly more than 2.25 X broader than its length, anterior margin broader than head width across the eyes, anterior angles sharply toothed, humeral angles sub-acutely produced, lateral margins sinuate, length of pronotum 2.45 (2.2-2.55), width 5.8 (5.8-6.2); scutellum large with distinct apical lobe, apex narrowly rounded, length of scutellum 4.6 (4.1-4.95), width 3.75 (3.3-3.85); metathoracic scent auricle ( Fig. 3) with peritreme lobe-like, not reaching to ½ distance of evaporatoria, apex narrowly round, anterior margin concave, posterior margin convex, ostiole somewhat oval; length base scutellum-apex clavus 3.3 (3.1- 3.8); apex clavus-apex corium 2.4 (2.2-2.6); apex corium-apex abdomen including membrane 1.7 (1.7-2.3); apex scutellum-apex abdomen including membrane 3.1 (2.75-3.6).

Abdomen

Convex beneath; connexiva moderately exposed at repose; posterior margin of 7 th abdominal sternum medially concave, lateral margin slightly sinuate with acute angles. Total length 12.05 (10.75- 13.05).

Male genitalia

Pygophore ( Fig. 3C) quadrangular, dorsomedian surface concave with an elongate, large process at inner lateral margins, lateroposterior margin sinuate, lateral lobes narrowly rounded, ventro-median surface produced into a bifurcate lobe; paramere ( Fig. 3D) somewhat Fshaped, outer margin convex, apex of blade transversely truncate, inner prong beset with bunch of hairs; aedegaus ( Fig. 3E,F) with theca apically ventro-medially terminating into a prominent conical lobe, with pairs of bifurcated lateral appendages, later only medially membranous, dorsal membranous conjunctival appendages shorter than penial lobes, vesica longer than penial lobes.

Female genitalia

Female terminalia ( Fig.3G) with large somewhat quadrangular-shaped, 1 st gonocoxae meeting to each other, posterior margins sinuate; 9 th paratergiles large, flipper-like, passing beyond posterior margins of fused 8 th paratergites; later medially concave; 2 nd gonocoxae with posterior margin convex; posterior margin of proctiger concave; spermatheca ( Fig. 3H) with balloonshaped median dilation, proximally encircled by a sclerotized ring, proximal spermathecal duct more than 4 X the distal spermathecal duct, pump region tubular, medially slightly dilated, bulb spherical with three finger-like processes, third bifurcated.

Material examined

1 male Zair: Bambesa , leg J. Vrydagh 10,193 7 determined as C. trivalis by R. Linnavuori No. 7855 deposited at NHM Tervuren. Belgium; 2 female Wambasa , leg Dr. Degotte, 1936; 1 female Equateur, Bokuma , leg R. Lootens, 4,1954; 2 female Kibali, Nioka , 11,195 3, J. Hecq. determined as C. trivalis by R. Linnavuori No. 7855 deposited at NHM Tervuren. Belgium .

Comparative note

It is most closely related to C. nigriventris in having body pale brown or light brown with fine punctures, body of small or large sized, dorso-median surface of pygophore not deeply concave, but it could easily be separated from C. nigriventris in having body light brown with thick brown punctures, body moderate to large (10.75- 13.05mm), labium just reaching hind coxae, apical lobe of scutellum of moderate size with subround apex in contrast to body pale brown with fine brown punctures, size remarkably short (10.5-11.0mm), labium short extending to middle coxae and apical lobe of scutellum short with acutely pointed apex in C. nigriventris .