Image of Capitophorus xanthii (Oestlund 1886)
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Capitophorus xanthii (Oestlund 1886)

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Capitophorus xanthii (Oestlund)

Siphocoryne xanthii Oestlund, 1886:36 [neotype: apt.v.f., Hennepin Co., Minnesota, 10–IX–1898, Coll. 158/′98, Acc. 3537, OWO, on Xanthium; in OWO coll.].—Oestlund, 1887:71.—Williams, 1891:9.—Gillette and Baker, 1895:123.—Hunter, 1901:106.—Sanborn, 1906:274.—Wilson and Vickerey, 1918:180.

Capitophorus xanthii (Oestlund).—Oestlund, 1922:139.—Knowlton, 1927:238.—Gillette and Palmer, 1934:158–159.—Knowlton and Smith, 1937:152.—Patch, 1938:183, 246.—Palmer, 1952:273.—Knowlton, 1954:9.—Börner and Heinze, 1957:208.—Robinson and Bradley, 1965:41; 1968:61.

DIAGNOSIS.—This species can best be recognized by its anterior abdominal chaetotaxy of 2–1–1–2, short antennae, clavate cornicles, absence of posterodorsal caudal setae, and the large, widely expanded body setae. Its difference from C. shepherdiae have been mentioned under that species.

DESCRIPTION.—Apterous Viviparous Female: Color in life pale greenish, with dorsal markings of darker green (Oestlund, 1886:36). Body stoutly spindle-shaped; cleared specimen pale, with tips of rostrum, legs, cornicles, and areas around primary sensoria brown; tergum rather pronouncedly sculptured. Head with slightly developed laterofrontal projections, mesofrontal tubercle prominent; mf 1p, lf 1p, vlf 1p, df 4p, vf 3–6 (usually 3)p, pc 2p, ac 4 arranged 1–2–1, and md 1 or 2 on each side; dorsal setae stoutly bulbous, subsessile, borne on large tubercles, subequal in length; vf setae also capitate but thinner and shorter, pc, ac, and md elongate, mostly pointed. Antennal segment I conspicuously produced mesodistally, with 5–8 knobbed setae in addition to basal pointed one on dorsum. A.s.II with setae, similarly knobbed but smaller than those of preceding segment. A.s.IV and V subequal, about ⅔ length of a.s.III; unguis 3 to 4½ times (m = 3.62 ± .15, n = 27) as long as base of a.s.VI.

Arrangement of thoracic and body setae shown in Figure 47; prothorax with usual number of 8, arranged in 2 rows of 4; meso- and metathorax 2–1–2 (sp–p–m); first and fifth abdominal segment 2–1–1–1 (sp–p–sm–m); second to fourth abd.s. 2–1–1–2; abd.s. 6 and 7 also with 3 pairs of setal rows, spinals duplicate, other rows single; eighth segment with a pair of duplicate spinals, median one occasionally present, 1–4 others decreasing in size laterally. Cauda tapering, sometimes with slight distal constriction before acute tip; spiculate; with 2 lateral pairs, usually without posterodorsal seta (absent in 92 of 100 specimens seen). Cornicles clavate on distal ⅓, extreme apex narrowed slightly; faintly wrinkled on cylindrical base; concolorous with body, tip pale brown or dusky; 3¼ to 4½ times as long as cauda. Rostrum IV+V rostrate, with relatively long (about ¼ entire length of segment) sharply pointed apex; 1 basal, 1 dorsal, and 3 lateral pairs of setae present, ml distinctly removed from pi and lateral pairs subequal in length; slightly longer than second joint of hind tarsi.

Measurements (in mm) of neotype and 14 neoparatypes: BL 1.40–1.94 (1.78), We .37–.44 (.402); a.s.III .21–.29 (.239), a.s.IV .15–.20 (.166), a.s.V .15–.20 (1.69), a.s.VI .07–.09 (.081) + .25–.35 (.291); cornicles .58–.75 (.703), cauda .15–.21 (.182); hind tibiae .80–1.00 (.895), hind ta–2 .09–.10 (.098), rostrum IV+V .10–.12 (.115). Length of dorsal head setae: mf .0198–.0396 (.0291), lf .0220–.0308 (.0257), df–1 .0264–.0374 (.0329), df–2 .0242–.0352 (.0290), ipf .0220–.0308 (.0255), and opf .0176–.0308 (.0254). Proportions of a.s.III:IV:V, 1: .55–.82 (.69): .63–.81 (.71); VIu/VIb 3.00–4.29 (3.62); co/ca 3.22–4.41 (3.89); rostrum IV+V/ hind ta–2 1.10–1.22 (1.18).

Alate Viviparous Female: In life, yellowish green, with transverse dark green markings on abdomen (Oestlund, 1886:36). Cleared specimen with dark brown head, thorax, abdominal sclerites, tips of tibiae, entire tarsi, and antennae from near bases of a.s.III; anterior wing margin, wing veins, and distal ½ of cornicles dusky. Head and basal 2 antennal segments similar in chaetotaxy to those of aptera but setae relatively shorter, merely rod-shaped; all ventral setae but vf and vlf pointed. Sensoria distributed as follows: a.s.III 19–35 (28.26 ± 2.14, n = 19); a.s.IV 9–17 (13.74 ± 1.18, n =19); a.s.V 1–6 (3.47 ± .65, n = 19). Abdomen with well-defined, rectangular central sclerite, spinopleural sclerites on segments anterior and posterior to central sclerite and marginals less developed; setal pattern as in aptera. Cauda tapering to acute point, may be constricted distally, pinching off a small terminal knob (Figure 58); 2 lateral pairs of setae present, posterodorsal seta absent. Rostrum IV+V as in aptera, averaging 1¼ times length of hind tarsal segment 2.

Measurements (in mm) of 10 neoparatypes: BL 1.45–1.90 (1.72), We .36–.41 (.390); a.s.III .23–.32 (.283), a.s.IV .15–.23 (.188), a.s.V .16–.20 (.178), a.s.VI .07–.10 (.086) + .27–.36 (.328); cornicles .41–50 (.461), cauda .11–.16 (.136); hind tibiae .82–99 (.93), hind ta–2 .08–.10 (.092), and rostrum IV+V .11–.12 (.113). Proportions of a.s.III:IV:V, 1: .59–.82 (.67): .57–.70 (.63); VIu/VIb 3.33–4.38 (3.87); co/ca 2.93–3.85 (3.42); rostrum IV+V/ hind ta–2 1.10–1.50 (1.23).

Oviparous Female: Unknown? See notes below.

Alate Male: Similar to alate viviparous female except as follows: sensoria on a.s.III–V more numerous; cauda shorter, triangular, without a distal constriction, portion beyond last lateral pair of setae much shorter. Aedeagus oblong, with angular tip.

Measurements (in mm) of 3 specimens: BL 1.50–1.60 (1.55), We .38–.40 (.393); a.s.III .28–.32 (.303), a.s.IV .18–.20 (.195), a.s.V .18, a.s. VI .08–.09 (.085) + .20–.23 (.215); cornicles .35–.38 (.366), cauda .10–.11 (.107); hind tibiae .82–.84 (.83), hind ta–2 .09, and rostrum IV+V .11. Proportions of a.s.III: IV:V, 1: .58–.71 (.65): .56–.64 (.59); VIu/VIb 2.50–2.56 (2.53); co/ca 3.18–3.80 (3.58); rostrum IV+V/ hind ta–2 1.22. Number of sensoria on a.s. III 32–36 (33.8), on a.s.IV 16–24 (18.5), and on a.s.V 4–9 (6.8).

HOSTS.—Winter hosts: Elaeagnus angustifolia, Hippophae rhamnoides (Gillette and Palmer, 1934; Palmer, 1952).

Summer hosts: various species of Xanthium: X. strumarium var. canadense, X. echinatum, X. pennsylvanicum, and X. strumarium.

DISTRIBUTION.—Aside from type-locality (Minnesota) records exist for the states of Colorado, Idaho, Iowa, Kansas, Nevada and Utah, and Manitoba in Canada.

TYPES.—The material on which Oestlund based his original description of C. xanthii in 1886 no longer exists in his collection at the University of Minnesota. Its occurrence elsewhere is doubtful and no references to this possibility have ever been published; however, there is abundant material collected and determined by him at later dates. Comparisons of these later collections with his original description are in perfect agreement, and their conformity with his concept of this species is quite obvious. A neotype and neoparatypes are, therefore, selected from among these available specimens.

NEOTYPE.—Apt.v.f., with data indicated above.

NEOPARATYPES.—33 apt.v.f., 8 al.v.f., with same data as neotype; 5 apt.v.f. and 4 al.v.f., Minneapolis, Minnesota, 15–X–1890, on Xanthium; 20 apt.v.f. and 1 al.v.f., Excelsior, Minnesota 17–VIII–1910, coll. 70/′10, Acc. 4259, on X. canadense; 11 apt.v.f., Minneapolis, Minnesota, 14–VII–1912, Coll. 38/′12, on Xanthium; 5 apt.v.f. and 10 al.v.f., Minneapolis, Minnesota, 10–IX–1921, Coll. 82/′12, on Xanthium; and 1 apt.v.f. and 2 al.v.f., Minneapolis, Minnesota, Coll. 103/′21, on Xanthium. All neoparatypes collected by O.W. Oestlund and in his collection at the University of Minnesota.

SPECIMENS EXAMINED.—Aside from types: CANADA: Manitoba: La Salle, 1 apt.v.f. on 29–VI–1965, and Winnipeg, 1 al.v.f. on 12–X–1963, both collected by AGR, on X. strumarium. KANSAS: Manhattan, 3 al.v.f., 23–IX–1950, J.B. Kring, on the wing (KSU); Riley Co., 2 apt.v.f. and 5 al.v.f., 3–X–1949, J.B. Kring, on X. pennsylvanicum (KSU). MINNESOTA (also OWO slides): apterous and alatoid nymphs associated with types; Crookston, 17–VII–1897, 222/′97, Acc. 3386, on Xanthium; Minneapolis, 6 apt.v.f. on 8–IX–1903 (51/′03), 1 apt.v.f. and several ny. on 12–IX–1918 (83/′18), and 2 apt. v.f., 3 al.v.f., 3 al.m., and 4 altd.ny. on 1–X–1921 (129/′21), all on Xanthium; Ramsey Co., 19 apt. v.f. and many ny., 12–X–1907, 95/′07, on X. canadense. UTAH (all collected by GFK); Bear River City, 7 apt.v.f., 3 al.v.f., and 3 ny., 11–IX–1926, on X. echinatum (EOE coll.); Howell, 1 apt.v.f., 16–VIII–1925, on X. canadense (EOE coll.); Lewiston, 13 al. v.f., 15–IX–1926, on X. echinatum (GFK coll.); Tremonton, 5 apt.v.f. and 8 apt.ny., 28–VIII–1926, on X. echinatum (EOE coll.); and Washington, 4 apt.v.f. and 5 al.v.f., 9–VIII–1936, on Cocklebur (GFK coll.).
bibliographic citation
Corpuz-Raros, Leonila Alzate and Cook, Edwin F. 1974. "A revision of North American Capitophorus van der Goot and Pleotrichophorus Börner (Homoptera: Aphididae)." Smithsonian Contributions to Zoology. 1-143. https://doi.org/10.5479/si.00810282.156