Thyanta (Phacidium) robusta 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 robusta

description: Thyanta (Phacidium) robusta Rider, new species
Figs. 124- 138, Map 4
Description. Medium to large; dorsal surface dusky brown to greenish brown; broadly ovate, robust. Punctures brown, usually becoming fuscous near each humeral angle and in irregular band just posterior to transhumeral pale subcalloused line.
Apex of head evenly rounded; outer jugal margins nearly parallel for middle third of distance from eyes to apex (Fig. 125). Antennae brown, segments 1-2 sometimes vaguely marked with fuscous, segments 3-5 often reddish. Anterolateral margins of pronotum concave in dorsal view; humeral angles produced anterolaterad and dorsad, spinose (Fig. 124). Mesia! angle of each pronotal cicatrice marked with fuscous, sometimes only vaguely so. A raised transhumeral subcalloused line usually present. Disc of pronotum anterior to cicatrices depressed, punctures crowded, small. Hemelytra with exocorium of each more densely punctate than rest of corium; posterior margin of corium convex, costal angle narrowly rounded, usually reaching beyond middle of penultimate connexival segment (Fig. 124); hemelytral membranes hyaline with numerous fuscous flecks. Connexiva green to brown, posterolateral angles black, sometimes posterior margin of each segment marked with fuscous.
Ventral surface pale brown to green; punctures usually concolorous with surface, sometimes pale brown. Rostrum pale brown to green, apical half ofsegment 4 piceous, reaching to anterior margin of third (second visible) abdominal sternite. Ostiolar canals acuminate apically. Humeral angles often piceous. Femora and tibiae pale brown, tarsal segments darker, reddish; femora sometimes marked with a few pale brown spots, usually one dark brown to fuscous spot on superior surface at distal third. Postspiracular black spot usually present on each side of each abdominal sternite; posterolateral angle of each abdominal sternite piceous.
Mesial margins of basal plates in caudoventral view nearly straight; posterior margins sinuously convex; posteromesial angles weakly emarginate (Fig. 136). Sclerotized rod swollen subapically, distinctly narrowed apically (Fig. 137); spermathecal duct slightly swollen and coiled below proximal flange (Fig. 138). Posteroventral surface ofpygophore arcuately rounded; posterior margin in caudal view U-shaped, medial portion concave (Fig. 132). Pygophore in lateral view emarginate on dorsal half (Fig. 135); each lateral angle appearing double-cone-shaped in both ventral and dorsal views (Figs. 133, 134). Each paramere robust, apex nearly spinose in medial view (Fig. 126); apex narrowly rounded, curved slightly mediad in ectal view (Fig. 128); roughened, spiculate area on lateral surface linear, short (Fig. 127). Each lateral conjunctiva! lobe ofaedeagus with 1-2 diverticula (Fig. 131); dorsomedial conjunctiva! lobe apparently absent (Fig. 130); penisfilum and median penial lobes prominent (Fig. 129).
Measurements. Total length 7.41-9.78 (7.41); total width 6.47-8.04 (6.47); medial length ofpronotum 1.71- 1.99 (1.71). Medial length of scutellum 3.31-4.08 (3.40); basal width 3.20-3.84 (3.28); width at distal end of frena 1.21-1.66 (1.40). Length ofhead 1.62-1.81 (1.62); width 2.08-2.36 (2.12). Length of segments 1-5 ofantennae 0.40-0.52 (0.40), 0.81-0.94 (0.81), 1.07-1.20 (1.07), 1.14-1.25 (1.14), and 1.16- 1.21 (1.21), respectively. Length of segments 2-4 ofrostrum 1.25-1.62 (1.25), 0.74-0.81 (0.74), and 0.77-0.96, respectively.
Holotype. 5 labeled "ANA RECK (MUN. CAXIAS DO SUL R. S. 9-IV-55, BRASIL E. W. GRUMAN leg." Deposited in the Florida State Collection of Arthropods (Gainesville).
Paratypes. 255, 522. Labeled same as holotype (5 FSCA); (a) " SAO PAULO Br., Mraz " (b) "Z.M.B. Hem." (5 ZMB); (a) " Gramado, R.G. do Sul, Brasil 6-1-50 J. Becker 123" (b) " Thyanta det RISailer" (c) " Thyanta acuta Ruckes varietal form" (d) "Compared with type. Much more robust. H. Ruckes" (2 USNM); " GRAMADO 2. 1954 RGS BRASIL " (2 MZRS); " Brazil, Parami 30 mi. W Irati 23 FEB 1980 D.B. Thomas Coll." (2 DBT); (a) " Tasimbe 2411 57'' (b) "218" (2 MZRS); and (a) " Pinheinal 28 I 53 " (b) "217" (2 MZRS).
Distribution. Brazil (Map 4).
Comments. This is a fairly distinctive species, although it is closely related to T. acuta and T. cornuta. It can be separated from these species by the larger, more robust shape, and by the characters of the male genitalia. The double-cone-shaped posterolateral angles of the pygophore in ventral and dorsal views will separate this species from both T. acuta and T. cornuta.
Etymology. Named for the robust form of the humeral angles.
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 27-29