Thyanta (Argosoma) similis Van Duzee

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 : 70-72

Thyanta (Argosoma) similis Van Duzee

Figs. 357-363

Thyanta similis Van Duzee, 1933:26-27 ; Barber, 1934:282; Linsley and Usinger, 1966: 133; Froeschner, 1981:71; Froeschner, 1985:43-44.

Diagnosis. Small; ovate; distinctly convex. Green to testaceous often marked with dark rubescence on scutellum, hemelytra, and posterior disc of pronotum. Scutellum with medial longitudinal band from base to near apex nearly impunctate, subcalloused, cream-colored.

Apex of head broadly rounded; outer jugal margins subparallel for middle third of distance from eyes to apex ( Fig. 358); dorsal surface ofhead evenly but distinctly convex transversely. Anterolateral margins of pronotum concave in dorsal view; humeral angles rounded ( Fig. 357). Pronotal cicatrices immaculate. Ostiolar canals acuminate apically. Mesial margins of basal plates in caudoventral view straight to slightly convex; posterior margins sinuously convex; posteromesial angles truncated ( Fig. 361). Distal end ofsclerotized rod slightly swollen subapically, narrowed apically ( Fig. 362); spermathecal duct slightly swollen below proximal flange ( Fig. 363). Posterior margin of pygophore sinuously U-shaped in caudal view ( Fig. 359); concave in lateral view. Apex of each paramere spinose in ectal view; narrowly rounded in medial view; dorsomedial concave surface oriented more dorsad than mediad; roughened spiculate area on lateral surface circular.

Types. Van Duzee (1933) described T. similis from 2'i!'i! both collected in the Galapagos Islands. Both specimens were examined and are conserved in the California Academy of Sciences (San Francisco).

Distribution. Known only from the Galapagos Islands, Ecuador.

Specimens examined. Five specimens collected between 22 January and 24 April; deposited in CAS, DAR, SMEK. ECUADOR: GALAPAGOS ISLANDS: Floreana Island: Post Office Bay . Rabida Island . Santa Cruz Island: Academy Bay .

Comments. Thyanta similis and T. setigera are the only two species of Thyanta known to occur in the Galapagos Islands. These two species are easily separated by the shape of the humeral angles, which are rounded in T. similis and angulate to spinose in T. setigera. Thyanta similis is the only species in the genus that has the medial portion of the scutellum nearly impunctate and subcalloused.