Author Institution: Department of Zoology and Entomology, The Ohio State University, Columbus, OhioA tenebrionid beetle from southwestern United States, Megasida tenuicollis New Species, is described. Two species of this genus are now known from north of the Rio Grande River, the other being M. obliterata (Champion). Ecological and distributional data are presented for both species and their diagnostic characters are discussed and illustrated

Triplehorn, Charles A.

The Ohio Journal of Science

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NOTES ON THE SPECIES OP MEGA SWA CASEY FROMTHE UNITED STATES1(COLEOPTERA: TENEBRIONIDAE)CHARLES A. TRIPLEHORNDepartment of Zoology and Entomology, The Ohio State University, Columbus, OhioABSTRACTA tenebrionid beetle from southwestern United States, Megasida tenuicollis NewSpecies, is described. Two species of this genus are now known from north of the RioGrande River, the other being M. obliterates (Champion). Ecological and distributionaldata are presented for both species and their diagnostic characters are discussed andillustrated.The genus Megasida was erected by Casey (1912, p. 202) for certain large,glabrous species previously placed in the genus Asida. These are characterizedb}^  having the prosternal process deflexed behind the coxae and the terminal seg-ment of the maxillary palpus sexually unmodified. They are similar to the largespecies of Stenomorpha, but in this latter genus the base of the pronotum is con-spicuously and broadly lobed medially and the terminal segment of the maxillarypalpus is large and scalene in the male, smaller and recti-triangular in the female.Casey based his description of the genus on Asida obliterata Champion, whichhe selected as the type of the genus. He also included six more of Champion'sspecies from northern Mexico in the genus although it appears unlikely that heever saw any of them.Pallister (1954) described two new Mexican species in Megasida, bringing thetotal to nine species currently placed in the genus. Until now, but one species,M. oblilerata, has been recognized as occurring north of the Rio Grande.Casey recorded obliterata from El Paso, Texas, just across the Rio Grande fromthe type locality, Paso del Norte (Ciudad Juarez), Chihuahua, Mexico. It hasalso been recorded from southern Arizona (Horn, 1894, p. 421), but I have neverseen one from that state.On a recent collecting trip,2 this species was found in large numbers at WhiteSands National Monument, Otero County, New Mexico. Dr. Howard V. Weems,Jr., and I, aided by our families, collected 150 specimens within a fifty-yard radiusof the wall surrounding the Monument headquarters on the evening of August 19,1962. The beetles appeared shortly before dusk in company with several speciesof Eleodes and were moving rapidly about. Several hours later their numbers haddiminished markedly, and most of those still above ground were scarcely moving.This large series was identified as Megasida obliterata (Champion) and wasverified by Mr. T. J. Spilman of the United States Department of Agriculture.Through the courtesy of Mr. J. Balfour-Browne of the British Museum, I wasable to study two specimens from Champion's Paso del Norte series and concludethat Casey's determination of this species was correct. Each of the two specimensperfectly match our specimens from White Sands, New Mexico.During the study, a second species of Megasida was found north of the RioGrande River. The two species may be separated by the following key:1. Elytra minutely and inconspicuously punctured, surface dull; pronotum with basalangles obtuse or rectilinear, not prolonged caudad obliterata (Champion)1'. Elytra coarsely and densely punctured, surface shining; pronotum with basal anglesacute and prolonged caudad over humeri tenuicollis n. sp.Manuscript received November 11, 1966.Sponsored by the American Philosophical Society (Grant No. 3091, Penrose Fund).THE OHIO JOURNAL OF SCIENCE 67(1): 38, January, 1967.No. 1 MEGA SI DA FROM U.S. 39Megasida obliterata (Champion)(Fig. A)Asida obliterata Champion, 1892, p. 497; Horn, 1894, p. 421.Megasida obliterata (Champion), Casey, 1912, p. 203.Elytra dull and irregularly, finely wrinkled to almost smooth, minutely and inconspicuouslypunctured; at least an indication of a lateral marginal carina or obtuse angulation present andextending more than halfway from base to apex (one exception); trace of two discal costaesometimes evident; basal angles of pronotum obtuse and not extending backward over humeri;apex of elytral margin sharply reflexed, thin; abdominal sterna minutely scabrous and withA. Megasida obliterata (Champion) 9 . White Sands National Monument, New Mexico.B. Megasida foeda (Champion) 9. Villa Lerdo, Durango, Mexico.C. Megasida tenuicollis New Species 9 • Brewster County, Texas.Line = 10 mm.Photograph by Robert B. Welch, Department of Photography, The Ohio State University;drawings by the author.widely spaced, extremely fine, asperate punctures on apical three segments. Measurements(d\ 9 ): Length: 19-26 mm.; width: 9.4-13.5 mm. Distribution: NEW MEXICO: (5) Alamagordo,August 27, 1960, C. A. & W. E. Triplehorn; (1) Deming, September 26, 1960, J. G. Watts; (159)White Sands National Monument, August 19-21, 1962, C. A. & W. E. Triplehorn, H. V. &Camilla Weems; (28) Las Cruces, September 7, 1966, F. J. Moore. TEXAS: (1) Brewster County,Rt. 385 entrance to Big Bend National Park, August 25, 1960, C. A. & W. E. Triplehorn; (5)Culberson County, August 30, 1940, D. J. & J. N. Knull; (1) El Paso, August 30, 1940, D. J.& J. X. Knull; (2) 9 miles west of Sierra Blanca, August 18, 1962, C. A. Triplehorn & H. V.Weems, Jr.; (1) 8 miles w. of Sterling City, September 1, 1962, H. V. Weems, Jr.40 CHARLES A. TRIPLEHORN Vol. 67Megasida tenuicollis n. sp.(Fig. C)Holotype (9 ) . Large, stout, moderately inflated posteriorly, convex, shining, glabrous,minutely alutaceous and dark reddish-brown throughout. Head moderately coarsely andsparsely punctured. Pronotum slightly broader than long; base two-tenths wider than apex,lateral margins arcuate, moderately reflexed, broadest about middle, feebly sinuate in basalhalf, straight and converging anteriorly; apical margin deeply emarginate, angles very acuteand prominent; basal margin sub truncate except at angles which are acute and prolongedcaudad over humeri, fitting inside humeral carina; disc evenly convex, minutely and sparselypunctate, more coarsely but still sparsely punctured laterally, reflexed portion coarselywrinkled. Elytra evenly convex from side to side, rather abruptly rounded laterally butwithout trace of a lateral carina except for a prominent, strongly reflexed humeral callus;surface, including inflexed portion, coarsely and rather densely punctured; punctures finer bas-ally, a series of fine grooves interspersed among punctures, epipleura in the form of a sharpD. Megasida foeda (Champion). Apex of female genital segment, ventral view.E. Megasida tenuicollis New Species. Apical sclerite of male aedeagus, dorsal view.F. Megasida tenuicollis New Species. Apex of female genital segment, ventral view.Line = l mm.carina at apical fifth of elytra, poorly defined anteriorly; apex not reflexed. Ventral surfaceof thorax finely and very sparsely punctured; abdominal sterna finely punctured, more coarselyso laterally, punctures connected by a network of fine creases, areas subtended by these creasesextremely minutely but densely punctulate and alutaceus. Female genitalia (fig. F) withapex of lateral valves elongate and thin. Male genitalia as shown (fig. E). Measurements:Length: 25 mm.; width: 12 mm. Type Locality: Green Valley (Brewster Co.), Texas, July 14,H. A. Wenzel (The Ohio State University). Paratypes: ARIZONA: (2) 7 miles north of Portal,July 12, 1963, Arthur Raske (on Opuntia). NEW MEXICO: (1) Alamogordo, August 27, 1960,C. A. & W. E. Triplehorn; (1) Lordsburg, July 17, 1955, D. J. & J. N. Knull; (1) White SandsNational Monument, August 19, 1962, C. A. & W. E. Triplehorn. TEXAS: (13) Brewster County,Green Valley, July 14, H. A. Wenzel; (1) 9 miles west of Sierra Blanca, August 18, 1962, C. A.& W. E. Triplehorn; (1) Oak Spring, Chisos Mts., August 15, 1962, H. V. Weems, Jr. Measure-No. 1 MEGASIDA FROM U.S. 41ments (cf, 9) : Length: 22-29 mm.; width: 11-14 mm. Variation: As with most tenebrionidbeetles, the females tend to be somewhat larger and more robust than the males. The sizeand shape of the pronotum vary considerably and the lateral margins in some are sinuate bothapically and basally; in others only the basal sinuation is evident. The lateral margins in onespecimen are evenly arcuate without trace of sinuations.The width of the pronotum ranges from 64.3 to 79.4 per cent of the elytral width (Average:75.2; Holotype: 72.0). The pronotum in all cases is quite evidently much narrower than theelytra.The elytral punctures vary slightly in depth and coarseness, and somewhat in their distanceapart. There is visually no trace of a lateral marginal carina on the elytra, but in one specimen(Chisos Mountains, Texas) there is a very distinct subcarinate ridge. Except for this specimen,the presence or absence of a lateral carina would have been utilized as another distinguishingcharacter separating obliterata from tenuicollis.Oddly enough, there is one specimen of obliterata (White Sands, New Mexico) in which thelateral carina is absent. In every other specimen it is quite evident.This species is very similar to Megasidafoeda (Champion) (fig. B) from Durango,Mexico, and specimens at hand compared favorably with the description of thatspecies. Two specimens of foeda, borrowed from the type series through thecourtesy of Mr. J. Balfour-Browne, proved to be very different in several importantrespects. The pronotum in the Durango specimens of foeda is extremely wide,nearly as wide as the elytra (88.2 and 90.9 per cent of elytral width). The sidesof the elytra are also more parallel than in tenuicollis. The illustration accom-panying the description indicates an extremely wide pronotum; since Championmentions no variation, it is assumed that this is characteristic of the species.Neither body conformation nor the relative size of pronotum in themselveswould have been cause for describing tenuicollis as a distinct species were it notfor the remarkably dissimilar lateral valves of the female genitalia of the twospecies. In foeda the valves are broad and short apically (fig. D). However,the external characters mentioned above appear to be quite diagnostic at leastwith the specimens available for study.It is interesting to note that on three separate occasions (Alamogordo andWhite Sands, New Mexico, and 9 miles west of Sierra Blanca, Texas) the twospecies M. obliterata and M. tenuicollis were collected together at identical locations.All specimens listed above are in The Ohio State University insect collectionand the Florida State Collection of Arthropods, except for the two paratypes ofM. tenuicollis from Arizona which are deposited in the California Academy ofSciences collection.LITERATURE CITEDCasey, Thomas L. 1912. A revision of the American genera of the tenebrionid tribe Asidini.Mem. Col., vol. 3, p. 70-214.Champion, George C. 1892. Biologia Centrali-Americana, Insecta, Coleoptera (Supplementto Heteromera), vol. 4, pt. 1, p. 477-524.Horn, George H. 1894. The Coleoptera of Baja California. Proc. Calif. Acad. Sci., ser. 2,vol. 4, p. 302-449.Pallister, John C. 1954. The tenebrionid beetles of north central Mexico collected on theDavid Rockefeller Mexican expedition of 1947 (Coleoptera: Tenebrionidae). AmericanMuseum Novitates, No. 1697, p. 1-55.

Notes on the Species of Megasida Casey from the United States (Coleoptera: Tenebrionidae)

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Notes on the Species of Megasida Casey from the United States (Coleoptera: Tenebrionidae)

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