J. New York Entomol. Soc. 103(4):360-363, 1995 ROLSTONUS ROLSTONI, NEW GENUS AND NEW SPECIES OF ACANTHOSOMATIDAE FROM ARGENTINA (HETEROPTERA: PENTATOMOIDEA: DITOMOTARSINI) Richard C. Froeschner — Abstract. Rolstonus rolstoni, a new genus and species from Argentina, is described and illustrated. Among the specimens of the family Acanthosomatidae in the National Museum mm of Natural History, Washington, D.C., is an unusual one measuring just 5.1 in length and representing a new genus and new species. It is my pleasure to name this Figs. 1-3. Rolstonus rolstoni, (1) dorsal habitus; (2) metapleuron; (3) male genital capsule, dorsal view with parameres in place. 1995 NEW ACANTHOSOMATIDAE 361 Fig. 1-3. Continued. new genus and new species Rolstonus rolstoni as a tribute to our friend and col- league, Dr. L. H. Rolston, who over many years, has published much from which we gained a more detailed understanding of the hemipterous superfamily Pentato- moidea in the New World. As yet, the host of this insect is unrecorded. 362 JOURNAL OF THE NEW YORK ENTOMOLOGICAL SOCIETY Vol. 103(4) Rolstonus, new genus Diagnosis: Ditomotarsinae: Ditomotarsini: Rolstonus is the only genus of the tribe Ditomotarsini with the combination of the juga distinctly surpassing and incurved (not quite in contact) beyond the tip ofthe clypeus (Fig. 1), the margins ofthe head concealing the antennophores in dorsal view, and the prostemum weakly convex. In Kumar’s (1974:5) key to the world’s genera of the tribe Ditomotarsini, Rol- stonus runs to the African genus Uhlunga Distant because it has a low but distinct mediolongitudinal carina on the mesosternum, but it differs from Uhlunga by nu- merous characters, the most conspicuous being the antennophores are concealedfrom dorsal view by the expanded margins of the head. In the keys to South American genera of Acanthosomatidae by Rolston and Kumar (1975:271) and by Froeschner (1981:8-9), it would be identified as Mazanoma Rolston and Kumarbecause itsjuga distinctly surpass the clypeus, but the sole member of that genus is much larger, measuring, 8.7-9.6 mm, has a strong, mediolongitudinal groove on the prostemum, and a strongly deflexed preocular part of the head. Characters: (Known from a single male). Outline oval, humeral angles weakly pro- tmding laterad of costal margin. Dorsal surface, except membrane, mostly closely punctate. Costal margin of hemelytron convex on apical two-thirds, without the “hump” of Kumar (1974). Head: Not deflexed anterior to eyes. Juga surpassing and incurved beyond apex of clypeus. Antennophores unarmed, hidden from dorsal view by expanded margins of head. Antennal segment I short, not reaching apex of head, V longest. Bucculae low, posteriorly rather abmptly terminated under eyes, a short distance from base of head. Labium reaching between posterior coxae, segment I not surpassing bucculae, subequal in length to IV, II and III equal, each somewhat longer than I or IV. Max- illary tubercle absent. Pronotal width slightly more than two-and-a-half times median length. Anterior margin deeply concave between eyes. Anterolateral margin expanded, carinate, out- line weakly convex; anterolateral angles vaguely projecting. Humeri rounded, no- ticeably projecting beyond costal outline. Scutellum triangular, slightly wider than long, apex acute, each basal angle with a small pale callous. Hemelytra slightly surpassing apex ofabdomen. Costal margin weakly convex on apical two-thirds. Mesocorium with apical margin straight, outerapical angles slight- ly rounded. Prostemum weakly convex, without mediolongitudinal groove. Propleuron and mesopleuron mostly shining, with numerous punctures. Metapleuron with widely separated punctures. Ostiolar canal elongate, narrow, distinctly grooved longitudi- nally, extending slightly less than half way from ostiolar opening to lateral margin of supporting sclerite (Fig. 2); evaporative area surrounding only basal part of os- tiolar canal and extending along narrow posterior margin ofmesosternum. All tibiae convex dorsally, without a subbasal angulation. Abdomen shining, finely alutaceous, virtually impunctate. Type-species: Rolstonus rolstoni new species, here designated. Etymology: This new genus is dedicated to a long time personal friend and a scholar of the New World Pentatomoidea, L. H. Rolston, and is formed by adding the Latin masculine ending us to his name. . 1995 NEW ACANTHOSOMATIDAE 363 Rolstonus rolstoni, new species Figs. 1-3 Diagnosis: As the only member of the genus, this species is recognized by the generic characters. Characters (measurements in mm): Holotype, 6 Length 5.1; width across humeral angles, 2.9. Antennal segments, I, 0.32: II, 0.47: III, 0.32; IV, 0.50: V, 0.63. Labial segments, I, 0.35: II, 0.58: III, 0.58: IV, 0.38. Colordull yellowish, irregularly marked with pale red; dorsally withpinkishareas, including many ofthe punctures, that give it a pinkish cast; abdomen ventrally with a broad, longitudinally sublateral, reddish-brown band. Male genitalia as in Fig. 3. Holotype male: Bariloche, Rio Negro, Argentina, Nov. 1926, R&E Shannon [Na- tional Museum of Natural History, Washington, D.C.]. Etymology: The species name reinforces the dedication to Dr. L. H. Rolston. Distribution: Known only from the holotype from Argentina. ACKNOWLEDGMENTS The author expresses sincere thanks to Young T. Sohn, Illustrator at the Smithsonian Insti- tution, forthe fine drawings; and to Drs. ThomasJ. Henry, Systematic EntomologyLaboratory, U.S. Department of Agriculture, Wayne N. Mathis, Department of Entomology, Smithsonian Institution, Washington, D.C., J. E. Eger, Dow Elanco, Tampa, Florida, and David A. Rider, Department of Entomology, Noth Dakota State University, for constructive reviews of the manuscript. LITERATURE CITED Froeschner, R. C. 1981. Heteroptera or true bugs of Ecuador: a partial catalog. Smithsonian Contrib. Zool. 322:i-iv, 1-147. Kumar, R. 1974. A revision ofworld Acanthosomatidae (Heteroptera: Pentatomidae): keys to and descriptions ofsubfamilies, tribes, and genera, with designation oftypes. Australian J. Zool., Supplementary Series No. 34:1-60 [a corrected title page amended the family group name to “Pentatomoidea”]- Rolston, L. H. and R. Kumar. 1975 (1974). Two new genera and two new species of Acan- thosomatidae (Hemiptera) from South America, with a key to the genera ofthe Western Hemisphere. J. New York Entomol. Soc. 82:271-278. Received 12 September 1996; accepted 26 September 1996.