Smicronyx (Pseudosmicronyx) obrieni Anderson, Korotyaev, and Lingafelter
Creators: name: Anderson, Donald M.
name: Korotyaev, Boris A.
name: Lingafelter, Steven W.
Publisher: name: Zenodo
Year: 2006
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Curculionidae
Smicronyx
Smicronyx obrieni

description: Smicronyx (Pseudosmicronyx) obrieni Anderson, Korotyaev, and Lingafelter,
New Species
Figs. 1–11
Description. Body elliptical, moderately stout, dermal color black. Vestiture abundant, squamulose, pale greyish white, with pearly lustre, shadowy dorsal pattern of pale brown in some specimens (Figs. 1–2). Rostrum (Figs. 3, 5) moderately stout, moderately curved, slightly tapered from base to apex, coarsely punctate behind antennal insertions, with 2 pairs of thin dorsal carinae (obsolete in females) before antennal insertions; scales recumbent except for 2 basal tufts. Basal groove separating rostrum from head shallow, distinct. Mandibles (Fig. 6) distinctly exarate. Head convex, black, shining, reticulate, bearing broad patch of appressed scales behind rostrum. Antennae (Figs. 3–4) inserted near mid-length of rostrum (females, Fig. 3b), or before middle (males, Fig. 3a); first funicular segment stout, subequal to combined length of second and third segments, second distinctly longer than third, remaining 4 segments subequal; setiform scales (Fig. 4d) pale grey, longest on seventh segment; club spindle-shaped, shorter than combined length of segments 3–7 (Fig. 4c). Prothorax moderately convex, slightly broader than long, slightly constricted behind apex; pronotum closely, evenly punctate, shining, without sculpturing, covered with flat, oval scales mixed with arched, flattened, setiform scales (Fig. 1). Elytra moderately convex, sides subparallel for about two-thirds length, converging to obtusely rounded apex, length slightly less than twice width across humeri; intervals flat, finely punctate, covered with 3–4 rows of flat, elliptical, overlapping scales and single row of arched, flattened, setiform scales (Fig. 1). Declivital callosities distinct, not prominent. Scutellum small, subtriangular, squamose. Underside closely covered with ovate, greyish-white scales, with modified striate and/or plumose scales on prosternum (Fig. 9c) and mesosternum (Fig. 9d). First and second ventrites together slightly longer than ventrites 3–5. Femora moderately clavate, unarmed, reddish brown, clothed with elliptical and elongate appressed scales. Tibiae (Figs. 7b, 8b) straight, reddish brown, thinly covered with mixture of elliptical and elongate appressed scales; row of 4–5 dark, stiff setae on inner margin, reduced to 3 on metatibiae; spurs slightly curved. Tarsi dark, reddish brown, squamose; third tarsomere distinctly broadest, bilobed; fifth tarsomere elongate, slightly longer than second and third tarsomeres combined (Fig. 7c, 8c); claws long, moderately divergent, fused near bases (Figs. 7d, 8d). Male genitalia as illustrated in Fig. 10, internal sac microspiculose, orificial plates fused dorsally; in lateral view, tegmenal strut sinuate with apex weakly, dorsally oriented (Fig. 10c); tegminal arms convergent, but indistinct dorsally. Female genitalia as illustrated in Fig. 11, arms of spiculum ventrale (apodeme of sternite 8) approximately Vshaped and anterior end of stem weakly expanded (Fig. 11a); hemisternites (coxites) weakly convergent apically with weakly divergent styli (Fig. 11a); spermatheca C-shaped but distinctly bulbous at proximal end near spermathecal duct and constricted at opposite end (Fig. 11b), with distinct striations around proximal third and slight indentation at inner margin of spermathecal body. Sexual dimorphism: Males distinguished from females externally by rostrum (Fig. 3) which is longer, smoother, and more polished before antennal insertions in females, and by fifth ventrite of the abdomen which is slightly depressed medially and barely sinuate at anterior margin in males (Fig. 9a), but nearly flat and transverse in females (Fig. 9b).
Measurements (in mm): Taken from specimens collected at one locality 12 mi. NE of Floydada, Texas; n 5 25 males, 25 females. Mean values are in parentheses. Males: Body L. 2.12–2.72 (2.41); Elytra L. 1.48–1.92 (1.69); Elytra W. 0.92–1.28 (1.07); Prothorax L. 0.56–0.76 (0.70); Prothorax W. 0.64–0.88 (0.76); Rostrum L. 0.88–1.12 (0.98). Females: Body L. 1.92–2.84 (2.46); Elytra L. 1.36–2.00 (1.75); Elytra W. 0.84–1.24 (1.09); Prothorax L. 0.48–0.72 (0.65); Prothorax W. 0.60–0.84 (0.75); Rostrum L. 0.88–1.24 (1.08).
Distribution. U.S.A.: Texas, New Mexico, possibly other southwestern states. RUSSIA (?): possibly established in Krasnodar Territory.
Biology. Given the many specimens collected from Ambrosia grayi (A. Nelson) Shinners (Asteraceae) in Texas, this plant is a probable host. This species is active in the late summer on ragweed.
Material Examined. Holotype (male) U.S.A., 12 mi. N[orth] E[ast] Floydada, Floyd Co., Texas, VIII-29-1970, on Ambrosia grayi [at] playa lake, C. R. Ward & C. W. O’Brien (USNM). Paratypes, U.S.A.: Texas, 12 mi NE Floydada, Floyd Co., playa lake, VIII-29-1970, on Ambrosia grayi, 227 Ex.; same except no host data, col. at night, 8 Ex. (USNM, CWOC). New Mexico, Ute Lake, 8-19-1970, D. Foster, 2 Ex., (CWOC). RUSSIA: Krasnodar Territory, Slavyansk District, ‘‘ Kuban’ ’ collective farm, on rice, VIII-1-1975, 6 Ex. (ZMAS); 2 Ex. (USNM).
Etymology. This species has been named in honor of Dr. Charles W. O’Brien, of Green Valley, Arizona, who took part in collecting the type series, and who kindly loaned those specimens.
Discussion. Some noteworthy features of this species are the long fifth tarsomere (Figs. 7d, 8d), which extends farther beyond the third tarsomere than in most other species of the subgenus Pseudosmicronyx, the slight, but distinct, pearly lustre of the vestiture (Fig. 1), the distinctive sinuate tegminal shape (from lateral view) (Fig. 10c), and the distinctive shape of the spermatheca (Fig. 11b). Smicronyx obrieni clearly belongs to the subgenus Pseudosmicronyx, and shares a number of basic features with the S. corniculatus group of species (see Anderson, 1962), of which several species are also associated with species of Ambrosia or the related genus Iva. However, the rostrum of female S. obrieni (Figs. 3b, 5c, d) is not as polished and terete before the antennal insertions as in the corniculatus group. Also, the surface of the pronotum is not sculptured with wavy ridges between the punctures, as in many species of the corniculatus group. Thus, the relationship of S. obrieni to the latter group remains unclear.
Two other undescribed species of Smicronyx resembling S. obrieni from Texas (CWOC) have a similar body shape and pale vestiture. Those species differ from S. obrieni in having shorter fifth tarsomeres, different punctation of the pronotum, and different shape and sculpturing of the rostrum. It should also be noted that S. obrieni may also be confused with other described species in the western USA having a similar habitus, particularly Smicronyx pallidus Anderson and S. albidosquamosus Klima, however the aforementioned characters will distinguish them. The latter two species have not yet been recorded from Texas or New Mexico. The status of the undescribed species mentioned here is based upon Anderson’s revision of the Smicronyx species of America north of Mexico (1962), and on his examination of the type specimens of the described Mexican Smicronyx species. The collection of the series of S. obrieni in Russia ‘‘on rice’’ is presumed incidental and we do not believe this is a host plant since the host of the long series from Texas was apparently A. grayi.
description: Published as part of Anderson, Donald M., Korotyaev, Boris A. & Lingafelter, Steven W., 2006, Discovery Of A New Species Of Smicronyx Schoenherr (Coleoptera: Curculionidae), pp. 243-251 in The Coleopterists Bulletin 60 (3) on pages 245-251, DOI: 10.1649/884.1, http://zenodo.org/record/4924242