Caystrus trivalis
Creators: name: Ahmad, I.
name: Zahid, M.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Pentatomidae
Caystrus
Caystrus trivalis

description: 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.
description: Published as part of 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, pp. 305-312 in Pakistan Journal of Zoology 41 on pages 309-310