Thyanta (Thyanta) setigera Ruckes

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 : 10-11

Thyanta (Thyanta) setigera Ruckes

Figs. 16-31

Thyanta perditor (of authors, not Fabricius): Heidemann, 1901:365; Barber, 1934: 282; Van Duzee, 1937: 112.

Thyanta setigera Ruckes, 1957c :l 79-180, figs. 7, 8; Linsley and Usinger, 1966: 133; Froeschner, 1981:71; Froeschner, 1985:43-44.

Diagnosis. Ovate. Dorsal surface green or brown, usually with at least partial transhumeral rubiginous band.

Apex ofhead broadly rounded; outer jugal margins sinuous, not parallel ( Fig. 17). Anterolateral margins of pronotum concave in dorsal view, immaculate, with at most a few weak denticles near head; each humeral angle acute, weakly spinose, oriented laterad, spine protruding beyond base of adjacent corium by less than half width of eye ( Fig. 16). Mesial angle of each pronotal cicatrice piceous. Postspiracular black spot present on both sides of each abdominal stemite; posterolateral angles and usually anterolateral angles of each abdominal stemite marked with black.

Mesial margins of basal plates in caudoventral view nearly straight, separated basally; posterior margins sinuous ( Fig. 29). Pygophoral opening subtended by semicircular impression; posterior margin in caudal view distinctly convex with medial V-shaped emargination ( Fig. 25), concave in lateral view ( Fig. 28).

Types. Ruckes (1957c) described T. setigera from 24M and 2n 2 specimens, all from the Galapagos Islands. The holotype and 27 paratypes were examined. The holotype is housctd in the California Academy of Sciences (San Francisco).

Distribution. Galapagos Islands, Ecuador.

Specimens examined. 39 specimens collected between 25 February and 17 June, and on 26 November; deposited in AMNH, CAS, CU, DAR, LACM, SMEK, UCB, USNM. ECUADOR: GALAPAGOS ISLANDS: Fernandina Island : nr. Espanola Island . Gardner Island: nr. Espanola Island . Isabela Island: Banks Bay ; Tagus Cove . N. Seymour Island. Rabida Island . San Cristobal Island . Santa Cruz Island: I. 5 mi N Academy Bay ; Bellavista ; Conway Bay ; Sullivan Bay . Santiago Island .

Comments. The only other species of Thyanta that occurs on the Galapagos Islands is T. similis. Thyanta setigera is easily separated from T. similis by the spinose humeral angles. The humeral angles are rounded in T. similis.

The relatively short humeral spines of T. setigera, protruding beyond the base of the adjacent corium by less than the width of an eye, readily distinguish this species from T. perditor . The only other related species occurring in South America is T. rubicunda which has strong denticulations along the anterolateral pronotal margins and usually lacks any black markings on the anterolateral angles of the abdominal segments. In contrast, Thyanta setigera has reduced pronotal denticulation and usually the anterolateral angle of each abdominal segment is marked with black.