Thyanta (Phacidium) convexa, Rider, 1991

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 : 18-20

Thyanta (Phacidium) convexa Rider, new species

Figs. 64-78, Map l

Description. General form ovate, distinctly convex. Dorsal surface stramineous to pale brown, punctures dark brown to dark green, a few interstitial pale points scattered on each corium.

Dorsal surface of head transversely convex; juga and tylus subequal in length or tylus slightly longer than juga. Outer jugal margins subparallel for middle third of distance from eyes to apex ( Fig. 65). Antennae pale brown to green, segments 3-5 usually faintly darker on distal half of each segment. Anterolateral pronotal margins weakly convex in dorsal view ( Fig. 64), concolorous with rest ofpronotum. Humeral angles narrowly rounded, protruding slightly beyond base of adjacent coria ( Fig. 64). Pronotal cicatrices immaculate. Apex of each corium narrowly rounded, usually reaching beyond middle of penultimate connexival segment; posterior margin of corium convex; hemelytral membranes hyaline with several faint brown flecks. Connexiva pale brown, posterolateral angle of each segment usually black.

Ventral surface pale brown to green; abdominal punctures concolorous with surface; punctures on thoracic pleura usually dark brown. Posterior termination of each buccula roundly truncate. Rostrum reaching to posterior margin of third (second visible) abdominal segment. Ostiolar canal acuminate distally. Legs pale brown to green. Postspiracular black spot usually present on each side of each abdominal sternite. Posterolateral angles of abdominal sternites piceous.

Mesial margins of basal plates in caudoventral view convex; posterior margins sinuous, slightly concave, posteromesial angles rounded ( Fig. 78). Sclerotized rod slightly swollen subapically, distinctly narrowed apically ( Fig. 76); spermathecal duct swollen and with much coiling below proximal flange ( Fig. 77). Posterior margin of pygophore in caudal view U-shaped, medial portion concave ( Fig. 69); posterolateral angles prominent in ventral and dorsal views ( Figs. 70, 71); posteroventral surface arcuately rounded, not produced caudad in lateral view ( Figs. 72). Apex of each paramere narrowly rounded in ectal view ( Fig. 68), curving distinctly dorsad in medial view ( Fig. 66); roughened, spiculate area on lateral surface circular ( Fig. 67). Each lateral conjuctival lobe of aedeagus with single rounded diverticulum ( Fig. 73); dorsomedial conjunctiva! lobe distinct ( Fig. 74); median penial lobes and penisfilum moderately prominent ( Fig. 73).

Measurements. Total length 6.31-7.18 (6.31); total width 4.10-4.73 (4.42); medial length ofpronotum 1.51-1.73 (1.51). Medial length ofscutellum 2.80-3.13 (2.83); basal width 2.65-2.98 (2.87); width at distal end of frena 1.03-1.25 (1.07). Length ofhead 1.64-1.81 (l.64); width 2.03-2.19 (2.06). Length of segments 1-5 of antennae 0.37-0.40 (0.37), 0. 70-0.81 (0.81), 0. 72-0.83 (0. 74), 0.98-0.99 (0.98), and 0.99-1.03 (1.03), respectively. Length of segments 2-4 of rostrum 1.21-1.42 (1.21), 0.66-0.74 (0.68), and 0.81-0.83 (0.83), respectively.

Holotype. cS labeled (a) " Peru S.A. III. 19 1937 E.G. Smyth " (b) "J.R.de la TorreBueno Collection K.U." Deposited in the Snow Entomological Museum, University of Kansas (Lawrence) .

Paratypes. lcS, 722. Labeled same as holotype (222 SMEK) ; labeled as holotype except " III. 16 1937 " (2 SMEK) ; labeled as holotype except "1.26 1936" (2 SMEK) ; (a) " Lima ( Peru) VI. 1939 leg. Weyrauch " (b) "WK W 5776" (cS USNM) ; " Peru. Dpto. Amazonas 43 K. ne. Chikiaco 1050' 6-10 XI 1978 L. J. Barkley " (2 LHR) ; (a) " PERU: 8 km. NE. Pucusana , Lima. IX- 12-54 " (b) " E.I.Schlinger & E.S.Ross collectors" (2 CAS) ; (a) " PERU Chancay river valley III- 15- 51 " (b) "Ross and Michelbacher Collectors" (2 CAS) ; (a) " ECUADOR Guayaquil " (b) " 12- 1-53 at light" (2 USNM) .

Distribution. Ecuador and Peru (Map l).

Comments. Thyanta convexa and T. aeruginosa are very similar in general appearance and are the only two species in the genus that have the posterior termination ofeach buccula roundly truncate; in all other species it is evanescent. Thyanta convexa differs from T. aeruginosa in having the superior surface of each tibia sulcate and the juga and tylus subequal in length. Thyanta convexa further differs from all other congeners by the slightly convex anterolateral pronotal margins and the male genitalia.

Etymology. Named for the convex anterolateral margins of the pronotum.