Slaterocoris ambrosiae

Slaterocoris ambrosiae (Knight) Figures 12, 14–16; plate 1; map 2 Strongylocoris ambrosiae Knight, 1938: 5, fig. 2 (orig. desc.); Kelton, 1968: 1134: fig. 22 (disc.); Knight, 1970: 249, fig. 29 (disc.); Henry and Wheeler, 1988: 448 (catalog); Schuh, 1995: 196 (catalog). Slaterocoris ovatus Knight, 1970: 247 (orig. desc.); Henry and Wheeler, 1988: 450 (catalog); Schuh, 1995: 198 (catalog). NEW SYNONYMY. Slaterocoris arizonensis Knight, 1970: 248, fig. 30 (orig. desc.); Henry and Wheeler, 1988: 448 (catalog); Schuh, 1995: 197 (catalog). NEW SYNONYMY. Slaterocoris bispinosus Knight, 1970: 249, fig. 25 (orig. desc.); Schuh, 1995: 197 (catalog). NEW SYNONYMY. Slaterocoris severini Knight, 1970: 250, fig. 28 (orig. desc.); Henry and Wheeler, 1988: 451 (catalog); Schuh, 1995: 199 (catalog). NEW SYNONYMY. DIAGNOSIS: Distinguished from other Slaterocoris species by the conspicuous pale apex of the femur, the relatively pale tibia (fig. 12), the dense, suberect, brown simple setae (fig. 14C), and the male genitalia, especially the unique subapical tubercle of the left paramere (fig. 16C, D) and the basal spur on the base of the endosomal spicule (fig. 16A). REDESCRIPTION: Male: Moderately small, elongate; length 3.20–5.10, width 1.45–2.20 (pl. 1). COLORATION: Black, including antenna, coxa, femur, and tarsomeres; apex of femur narrowly, and hind tibia, pale (fig. 12); sometimes tibia black in Puebla (Mexico) specimens. VESTITURE: Dense, moderately long, suberect brown simple setae (fig. 14C). STRUCTURE: Hemelytral length variable, costal margin sublinear; frons smooth (fig. 14A, B); mesothoracic spiracle and metathoracic scent-efferent system as in figure 14D. GENITALIA: Pygophore: Tergal process short, bifurcate with right side point directed toward midline (fig. 14E). Phallotheca: Left lateral surface slightly compressed (fig. 16B). Endosomal spicule: Ventral lobe of uniform thickness throughout apical region with weak marginal serration; dorsal lobe bifurcate with narrow, smooth rami (fig. 16A), sometimes rami sparsely serrate; base with spur (fig. 16A, arrow). Right paramere: Small; apical region with variable number of ventral spines; medial region with prominent pointed or serrate spine; basal lobe prominent, pointed or serrate (fig. 15A–J); sometimes strongly produced (fig. 15C). Left paramere: Distal portion shorter than basal portion; distally with prominent subapical process (fig. 16C, D). Female: Moderately small, obovate; Length 3.30–4.20, width 1.70–2.09 (pl. 1). STRUCTURE: Costal margin strongly convex. GENITALIA: First gonapophyses: Left overlapping right, in ventral view; left greater than right at overlap; right lateral surface small. Left first gonapophyses: Dorsal surface concave, apex wide. Vestibulum, anteroventral margin of anterior wall: Sclerotized medially and sclerotized to lateral margins of bursa copulatrix. Ventral labiate plate: Strongly produced moderately, base wide, triangular. Second gonapophyses: Anterior medial surface strongly convex. Interramal sclerite: Dorsomedial region flat, not produced anteriorly; posteromedial portion with tumid process abutting ovipositor bulb; lateral ventromedial regions overlapping ventromedial plate. Interramal lobe: Dorsal or basal insertion with membranous attachment; dorsomedial margin not produced as lobe; ventral projection long with concave anterior surface. HOSTS: Records indicate that the predominant breeding hosts are species of the widespread and common genus Ambrosia (Asteraceae). In the southwestern portion of the range (Arizona and California), the hosts are A. confertiflora, A. dumosa, A. eriocentra, and A. psilostachya. Annual ragweed, A. artemisiifolia, is the only species known from the eastern portion of the range of S. ambrosiae. A very few specimens were taken from other Asteraceae: Chrysothamnus sp., Encelia farinosa, E. frutescens, Gurierrezia sp., Hymenoclea salsola, Iva axillaris, and Parthenium sp. Single specimens were found on non-Asteraceae listed in the ‘‘Specimens Examined’’ below; these are considered to be sitting records. DISTRIBUTION: Widely distributed in North America, from extreme southwestern Ontario, Canada, and adjacent Michigan, west across the midwestern United States from South Dakota to Iowa, and south to Texas and California. In Mexico, S. ambrosiae is known from the eastern portion of the Central Plateau in Durango, south across the Sierra Madre Oriental of Nuevo Leon, and reaching its southern limit in the Sierra Transvolcanica from Jalisco to northern Puebla (map 2). The ruderal ecology of the hosts of S. ambrosiae certainly account for its wide habitat range in forest, grassland, and desert environs. COLLECTION SUMMARY: 601 specimens from 167 collection events with earliest (March) and latest (December) records from Texas. The bulk of the collection events from the southern U.S. (Texas west to California) occur in April and May, with June to August dates predominating as the season progresses farther north. Collection dates from Mexico extend from July to September, with the latest (November) from Nuevo Leon. DISCUSSION: The subapical tubercle of the left paramere and the prominent spur on the left side base of the ventral lobe of the endosomal spicule are unique to S. ambrosiae; however, there is no question concerning the correct generic placement of this species, as all the diagnostic characters of Slaterocoris are present. Based on the cladistic analysis, S. ambrosiae was not placed in a species group, but as the sister to a large number of species (figs. 1A–D, 2). Two characters support this arrangement: dense dorsal vestiture (10-2) and long ventral projection of the interramal lobe (69-2). Knight (1938) described S. ambrosiae based on numerous males and females from Kansas, South Dakota, and Texas. Kelton (1968) and Knight (1970) distinguished it by the small body size, black antennae with short segment II, relatively long, brownish black vestiture, smooth frons, and right paramere of the male. All of these characteristics are variable throughout the range of S. ambrosiae. In males, the body length ranges from 3.20 to 5.10, antennal segment II length 0.70–1.20, ratio of the length of segment II to head width 0.83–1.31, and the structure of the right paramere is variable in the apical, medial, and basal spinose regions (cf. fig. 15A–J). Based on a limited number of specimens, Knight (1970) described four nominal species, distinguished by setal color and a short antennal segment II: S. arizonensis (8 holotype + 18, 1♀ paratypes —AZ, NM, ZA), bispinosus (8 holotype + 5♀ paratypes —SL), ovatus (♀ holotype, 1♀ paratype —CA, TX), and severini (8 holotype — SD). Each typifies an extreme condition in one or more of the variable ‘‘diagnostic’’ features. Knight (1970) separated his nominal species and S. ambrosiae based on vestiture color (dark black or brown vs. pale golden or silvery) and density (dense vs. sparse), ratio of length antennal segment II and head width, and right paramere structure (basal spine bifurcate or not). Only two structures of the male genitalia, the bifurcate apex of the left paramere (fig. 16C, D) and the prominent spur on left basal shoulder of the endosomal spicule (fig. 16A), are invariant in all specimens (the condition in ovatus is inferred from examination of external features). Additionally, the dorsal vestiture is relatively dense, long, suberect, and brown to black, the tibiae are yellow, the hemelytral membrane length is sexually dimorphic in some populations, and all known breeding hosts are species of Ambrosia. Because I cannot find constant differences in size, ratio, or genitalic structure to support the four nominal Knight (1970) species, and all fit within the variation established for these characters based on examination of specimens from throughout the range, I am treating all of them as junior synonyms of S. ambrosiae. Among specimens of S. ambrosiae in the CNC, some from Durango, Mexico, have Kelton’s manuscript name ‘‘ durangoensis ’’affixed. A male from this collection event has an apparently aberrant prominent basal lobe of the right paramere (fig. 15C); others from the same population are typical of the species as in figure 15A, D. Some males with long hemelytra from San Miguel Texmelucan, Puebla, have dusky brown to black tibia, others from the same collection event have typically pale tibiae and are otherwise identical to other S. ambrosiae. The extremes of variation in right paramere morphology of S. ambrosiae are documented in figure 15A–J. In the apical region there appears to be a tendency for the ventral and medial spines of the right paramere to be smaller than the dorsal spine, and the ventral and medial spines are situated closer together and slightly removed from the dorsal spine. HOLOTYPES: MEXICO: San Luis Potosi: 10 mi S of Rio Verde [1.529526 N 99.037176 W], 28 Jul 1970, Murray, Phelps, Hart, Schaffner, 18 (AMNH_PBI 00122240) (USNM) (S. bispinosus: junior synonym). USA: Arizona: Pinal Co.: Superior [33.293896 N 111.095566 W, 732 m], 16 Apr 1928, A.A. Nichol, 18 (AMNH_PBI 00133386) (USNM) (S. arizonensis: junior synonym). California: San Bernardino Co.: Barstow [34.898596 N 117.022816 W], 21 May 1938, J. Standish, 1♀ (AMNH_PBI 00122258) (USNM) (S. ovatus: junior synonym). South Dakota: Hanson Co.: Emery [43.601676 N 97.622226 W], 24 Aug 1927, H.H. Knight, 18 (AMNH_PBI 00134025) (USNM) (S. ambrosiae: senior synonym). Lincoln Co.: Newton Hills [Canton, 43.224436 N 96.580046 W], 24 Jun 1935, H.C. Severin, 18 (AMNH_PBI 00122265) (USNM) (S. severini: junior synonym). OTHER SPECIMENS EXAMINED: CANADA: Ontario: Harrow, 42.033336 N 82.916666 W, 10 Aug 1997, P. Livingston, 18 (00329759) (DEBU); 14 Jul 1998, C. Teissen, (Fabaceae), 18 (00111336) (CNC). MEXICO: Coahuila: Cerrito, 20 mi SE of Saltillo, 25.211046 N 100.772536 W, 18 Jul 1963, H. and A. Howden, 18 (00111341), 1♀ (00

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