Thyanta (Phacidium) juvenca Stal

Rider, D. A. & Chapin, J. B., 1991, Revision Of The Genus Thyanta Stal, 1862 (Heteroptera: Pentatomidae) I. South America, J. New York Entomol. Soc. 99, No. 1, pp. 1-77 : 22-24

Thyanta (Phacidium) juvenca Stal

Figs. 94- 108, Map 4

Thyanta juvenca Stal, 1862b:104 ; Stal, 1872:35; Lethierry and Severin, 1893: 148; Berg, 1900:89; Kirkaldy, 1909:94; Jensen-Haarup, 1928:189.

Euschistus juvencus: Walker, 1867:247 .

Pentatoma pilosum Reed, 1898: 132 . (syn. by Kirkaldy, 1909)

Diagnosis. Medium-sized; slightly convex dorsally, distinctly convex ventrally. Dorsal surface pale to medium green, usually with yellow or red markings on apex of tylus, on apex of scutellum, on each humeral angle, and on legs.

Apex of head narrowly rounded; outer jugal margins sinuous, not parallel ( Fig. 95). Anterolateral margins of pronotum straight to slightly concave in dorsal view; humeral angles obtusely to narrowly rounded, protruding only slightly beyond base of adjacent coria ( Fig. 94). Each pronotal cicatrice usually immaculate, sometimes marked with black in mesial angle.

Mesia} margins of basal plates in caudoventral view straight to slightly convex; posterior margins sinuously convex; posteromesial angles rounded ( Fig. 106). Sclerotized rod relatively short, swollen subapically; narrowed apically ( Fig. 107); spermathecal duct with large amount of swelling and coiling below proximal flange ( Fig. 108). Posterior margin of pygophone shallowly and sinuously U-shaped in caudal view ( Fig. 102); posteroventral surface of pygophore straight in lateral view ( Fig. 105); slightly convex in ventral and dorsal views ( Figs. 103, 104). Each paramere robust; apex spinose, curved gently laterad in ectal view ( Fig. 98), curving gently dorsad in medial view ( Fig. 96); shaft with nearly angulate protuberance at middle; roughened, spiculate area on lateral surface linear ( Fig. 97). Each lateral conjunctiva! lobe of aedeagus with single rounded diverticulum ( Fig. 101); dorsomedial conjunctiva! lobe moderately large ( Fig. 100) penisfilum prominent, median penial lobes small, inconspicuous ( Fig. 99).

Types. Stal (1862b) described T. juvenca from lo from Chile. In the original description, he states that the type specimen was placed in the "Mus. Helsingfors" in Finland. The type specimen was not located in the Universitetets Zoologiske Museum (Helsingfors, Finland). However, the original description is adequate to fix the species. In his description, Stal says "Thorax marginibus lateralibus anticis integris, levissime sinuatis, angulis lateralibus obtusus, vix prominulis." Only three species of Thyanta are known to occur in Chile: T. juvenca, T. xerotica and T. rubicunda. Thyanta xerotica is relatively rare and occurs only in the very northern areas of Chile. Thyanta rubicunda has each humeral angle produced into an acute spine. Thyanta juvenca is the only common and widespread species in Chile that has each humeral angle obtusely rounded as in the above description.

Reed (1898) described Pentatoma pilosum from 200 from Chile without designating a holotype. Theo labeled (a) "Sin. Hem. Chile Coll. EC Reed" (b) "CJ Drake Coll. 1956" is designated lectotype. Theo labeled (a) "Sin. Hem. Chile Coll. ECReed" (b) "CJ Drake Coll. 1956" (c) "Pent. spe nov." (d) "juvenca" (e) " Thyanta " is designated paralectotype. Kirkaldy (1909) properly placed this species as a junior synonym of T. juvenca. Both specimens were examined and are housed in the U.S. National Museum of Natural History (Washington, D.C.).

Distribution. Chile ( Map 4).

Specimens examined. 79 specimens collected from 7 September to 17 May; deposited in AMNH, CAS, CNC, DAR, EGER, ENGL, FSCA, LHR, MNHS, UCR, UCS, USNM, ZMB. CHILE: Atacama: Rio Manflas . Bibfo: Arauco ; Queime , E . Concepcion . Coquimbo: Rivadavia ; Vicuna . El Liberatador General Bernardo O'Higgins: Rancagua ; 10 km N San Fernando ; San Vicente de Tauga . Maule: Cauquenes ; La Jaula . Cord . Curic 6 ; coast nr . Mataquito R . Region Metropolitana de Santiago: Buin ; Co San Ramon ; Clovillo ; Curacavi ; El Canelo ; La Matancilla ; Los Maitenes ; Melocoton ; Quebrada Macul ; Quilicura ; Rinconada Maipu ; San Bernardino ; Santiago . Tarapaca: Arica . Valparaiso: La Cruz ; Los Andes ; Ocoa ; Papudo .

Comments. Thyantajuvenca is closely related to T. acutangu/a, which may actually be a subspecies ofthe former. The male genitalia ofthe two species are nearly identical. Thyanta juvenca has each humeral angle obtusely rounded, while in T. acutangula each humeral angle is distinctly angulate.