Thyanta (Phacidium) acuta Ruckes 1952
Creators: name: Rider, D. A.
name: Chapin, J. B.
Publisher: name: Zenodo
Year: 1991
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Pentatomidae
Thyanta
Thyanta acuta

description: Thyanta (Phacidium) acuta Ruckes
Fig. 139- 153, Map 4
Thyanta acuta Ruckes, 1952:67-68.
Diagnosis. Medium-sized; ovate. Dorsal surface green to dark brown, sometimes with the following structures reddish: two spots on posterior disc of pronotum, one on each side of middle, extending to include nearly entire dorsal surface ofpronotum; dorsal surface of head; marginal band on scutellum along each frenum; and all of hemelytra except exocorium.
Apex ofhead evenly rounded; outer jugal margins sinuous, not parallel (Fig. 140). Anterolateral margins ofpronotum concave in dorsal view; humeral angles produced primarily laterad and only slightly anterodorsad, spinose (Fig. 139). Mesial angle of each pronotal cicatrice piceous; transhumeral subcalloused line usually present.
Mesia! margins of basal plates in caudoventral view nearly straight; posterior margins sinous; posteromesial angles rounded (Fig. 151). Sclerotized rod swollen at about two-thirds distance from base, apical, narrowed portion elongate (Fig. 152); spermathecal bulb globose, slightly elongate, small amount of coiling of spermathecal duct below proximal flange (Fig. 153). Posteroventral surface of pygophore arcuately rounded; posterior margin in caudal view U-shaped, medial portion slightly concave (Fig. 147); pygophore in lateral view nearly arcuately convex (Fig. 150). Each paramere rather robust, apex nearly spinose in medial view (Fig. 141); blunt, robust in ectal view (Fig. 143); roughened, spiculate area on lateral surface slightly elongate (Fig. 142). Each lateral conjunctival lobe of aedeagus with 3-4 spinose diverticula apically (Fig. 146) and l hooked sclerotized diverticulum ventrally (Fig. 144); penisfilum large, dorsomedial conjunctival lobe apparently absent (Fig. 145).
Types. Ruckes (1952) described T. acuta from 1'3 and 19 from Paraguay. Although he described this species under the name T. acuta, the name placed on the label with the specimens is T. acutissimus. The remaining label information, however, matches exactly that given in the original description, and the specimens fit the description for T. acuta. The holotype was examined and is housed at the University ofMichigan Museum (Ann Arbor).
Distribution. Southern South America (Map 4).
Specimens examined. 4 l specimens collected from 2 September to 1 April; deposited in AMNH, CNC, LHR, MBR, MLP, USNM, ZMB. BOLIVIA: El Beni: Trinidad. La Paz: Apolo. Santa Cruz: Santa Cruz. BRAZIL: Raco. Mato Grosso: Cuiaba. Mato Grosso do Sul: Corumba; Salobra. Minas Gerais: 60 km W Araxa. Santa Catarina: Nova Teut6nia. Sao Paulo: Teodoro Sampaio. PARAGUAY: Caaguazu: Estancia Primera. Central: Lago Yloycaraiy, N of San Bernardino. Concepcion: Horqueta. Cordillera: Caacupe. Guaira: Villarrica. ARGENTINA: Misiones: lgazu; Leandre Alem; San Ignacio; Victoria.
Comments. This species is closely related to T. robusta and T. cornuta. It can be separated from T. robusta by the less robust form and by the form of the posterolateral angles of the pygophore, which are not double-cone-shaped when viewed ventrally or dorsally. The posterior margin of the pygophore in caudal view is U-shaped in T. acuta and V-shaped in T. cornuta.
description: Published as part of Rider, D. A. & Chapin, J. B., 1991, Revision Of The Genus Thyanta Stal, 1862 (Heteroptera: Pentatomidae) I. South America, pp. 1-77 in J. New York Entomol. Soc. 99 on pages 29-31