Thyanta (Argosoma) hamulata Rider 1991, new species
Creators: name: Rider, D. A.
name: Chapin, J. B.
Publisher: name: Zenodo
Year: 1991
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Pentatomidae
Thyanta
Thyanta hamulata

description: Thyanta (Argosoma) hamulata Rider, new species
Figs. 215-229, Map 3
Description. Dorsal surface green to pale yellowish-brown, usually no red or black markings present; punctures concolorous with surface.
Apex of head broadly rounded; outer jugal margins sinuous (Fig. 216). Antennae pale brown to green, distal segments slightly darker. Anterolateral margins of pronotum in dorsal view nearly straight; humeral angles obtusely rounded, protruding slightly beyond base of adjacent coria (Fig. 215). Pronotal cicatrices immaculate. Hemelytra uniformly and shallowly punctate; posterior margins weakly convex; costal angles narrowly rounded (Fig. 215), reaching beyond middle of penultimate connexival segments; hemelytral membranes hyaline, a few faint brown flecks sometimes present. Connexiva narrowly or not at all exposed, posterolateral angles of segments sometimes minutely marked with piceous.
Ventral surface pale yellow to yellowish-green; punctures concolorous with surface; rostrum yellow to green, apical half of segment 4 piceous; reaching onto third (second visible) abdominal stemite. Ostiolar canals acuminate apically. Femora and tibiae yellowish-brown to green, tarsal segments sometimes darker. Postspiracular brown spots sometimes vaguely present in brown form; posterolateral angles of abdominal stemites usually immaculate, rarely marked minutely with black.
Mesia] margins of basal plates in caudoventral view weakly convex, separated basally; posterior margins nearly straight; posteromesial angles rounded (Fig. 227). Sclerotized rod of nearly equal diameter throughout entire length, not at all swollen near apex; dilation of spermatheca constricted near middle, ending about threefourths distance from base of sclerotized rod (Fig. 228); spermathecal duct only slightly swollen and coiled below proximal flange (Fig. 229). Posterior margin of pygophore in caudal view broadly and shallowly U-shaped, posterolateral angles somewhat thickened (Fig. 223); chin-like protuberance prominent in ventral and lateral views (Figs. 224, 226); posterior margin nearly straight in dorsal view (Fig. 225). Each paramere with concave surface oriented dorsad; in ectal view, apex narrowly rounded, digitiform, curving gently laterad, with angulate triangular lateral lobe (Fig. 219); from medial view apex curving dorsad and caudad forming a distinct hook (Fig. 21 7); roughed, spiculate areas on lateral surface of paramere localized, circular (Fig. 218). Each lateral conjunctiva! lobe ofaedeagus with single diverticulum (Fig. 222); dorsomedial lobe present, but small (Fig. 221); penisfilum and median penial lobes of moderate size (Fig. 220).
Measurements. Total length 6.31-7.41 (6.39); total width 4.10-4.89 (4.10); medial length ofpronotum 1.32- 1.61 (1.32). Medial length ofscutellum 2.80-3.31 (2.80); basal width 2.58-2.98 (2.58); width at distal end of frena 0.88-0.99 (0.92). Length ofhead 1.34- 1.50 (1.37); width 1.88-2.08 (1.90). Length of segments 1-5 ofantennae 0.37-0.42 (0.37), 0.74-0.98 (0.74), 0.81-0.98 (0.81), 0.99-1.21 (1.05), and 1.10-1.14 (1.10), respectively. Length of segments 2-4 ofrostrum 1.18- 1.29 (1.18), 0.75-0.81 (0.81), and 0.59-0.74 (0.59), respectively.
Holotype. 5 labeled (a) " COLOMBIA: Dept. Valle del Cauca. Bitaco Valley, Finca Kyburz 1 km above Bitaco " (b) "Altitude 4500 ft. 27-28.Xl.1963 P. C. Hutchinson & J. K. Wright." Deposited in the California Academy of Sciences (San Francisco).
Paratypes. 855, 9'i?'i?. Labeled same as holotype (255 4'i?'i? CAS); (a) " PERU:Dept. Cajamarca Prov. Jaen. Pucara. Rio Huancabamba, 900m 14- 18.1.1964 " (b) "P. C. Hutchison and J. K. Wright Collectors" (555 2'i?'i? CAS), except 255; labeled " 10- 13.1.1964 "; " PERU: Dept. Amazonas Between Rio Maran.on and Bagua. 3-X-1964 P. C. Hutchison & J. K. Wright" (5 2'i?'i? CAS); and (a) " PERU: 94 mi. E. of Olmos, Lambayeque 1- 18- 1955 " (b) " E.I.Schlinger & E.S.Ross collectors" ('i? CAS).
Distribution. Northwestern South America (Map 3).
Comments. Only this species and T. acuminata have a distinct acute lateral lobe on each paramere. In T. hamulata, the lateral lobe is triangular, and the apex of each paramere curves dorsad and caudad, forming a distinct hook. In T. acuminata, the lateral lobe is spinose, and the apex of each paramere curves gently dorsad, not forming a distinct hook.
Only four species of Thyanta are known to lack the subapical swelling of the sclerotized rod of the spermatheca. Thyanta emarginata has the posteromesial angle of each basal plate deeply excavated. Thyanta hamulata can be separated from both T. brasiliensis and T. boliviensis by the constriction in the middle of the dilation of the spermatheca.
Etymology. Named for the hamulate or hooked apex of each paramere.
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 42-45