Aphid

Capitophorus elaeagni (del Guercio)

Myzus elaeagni del Guercio, 1894:189–199 [type: Italy, on Elaeagnus; believed to have been destroyed].—Schouteden, 1906a:32.—Davis, 1908:251–253; 1910:495.—Wilson and Vickerey, 1918:71.

Capitophorus elaeagni (del Guercio).—Patch, 1938:183.—Eastop, 1951:108.—Cottier, 1953:227–234.—Hille Ris Lambers, 1953:144–151.—Börner and Heinze, 1957:207–208.—Bodenheimer and Swirski, 1957:276.—Eastop, 1958:28–29.—MacGillivray, 1959:639.—Heinze, 1961:51, 53.—Heie, 1962: 221.—Smith, Martorell, and Escolar, 1963:44–46.—Shapo-shnikov, 1964:789.—Stroyan, 1964a:79:—Szelegiewicz, 1964:249.—Tuatay and Remaudière, 1964:266.—Leonard and Tissot, 1965:257.—Paik, 1965:55.—Pepper, 1965:191.—Robinson and Bradley, 1965:41.—Eastop, 1966:432–433.—Huculak, 1966:125.—Quednau, 1966:426.—Leonard, 1967:262.—Coon and Pepper, 1968a:1473; 1968b: 1474.—Leonard, 1968:8.—Robinson and Bradley, 1968:61.

Capitophorus elaeagni Van der Goot, 1913:84 [nomen nudum].

Myzus eloreagni [sic] Guercio.—Kirkaldy, 1906:12 [misspelling].

Capitophorus arctifoliae Shinji, 1924:359.

Myzus braggii Gillette, 1908:17–19 [type: Fort Collins, Colorado, on Cirsium arvense, USNM 41946].—Gillette and Bragg, 1915:102.—Jones, 1918:1–2.—Patch, 1918:90, 91.—Swain, 1919:73.—Patch, 1923:303.

Capitophorus braggii (Gillette).—Van der Goot, 1915:119–122.—Patch, 1918:90.—Takahashi, 1923:33.—Timberlake, 1924:456.—Hall, 1926:35.—Hori, 1929:82.—Judenko, 1930:166.—Takahashi, 1931:77.—Börner and Schilder, 1932:615.—Gillette and Palmer, 1934:146–147.—Mimeur, 1934:35–36.—Blanchard, 1935:366–368.—Cottier, 1935:357–358.—Tseng and Tao, 1936:150.—Knowlton and Smith, 1937:151.—Patch, 1938:182&244.—Blanchard, 1939:945–947.—Knechtel and Manolache, 1940:243–244.—Smith, 1940:141.—Blanchard, 1944:34.—Sampson, 1946:394.—Zimmerman, 1948:106–107.—Palmer, 1952:251–252.—Knowlton, 1954:8.—Essig, 1958:251.—Leonard, 1963:70.

Aphis cardui Linnaeus.—Sanborn, 1904:255 [in part].

Phorodon carduinum (Walker).—W. M. Davidson, 1912:409.

Capitophorus carduinus.—Oestlund, 1922:139 [not Walker, misidentification; Oestlund’s specimens seen].—Leonard, 1963:70 [not Walker, misidentification; apterous and alate viviparae from St. Louis, Missouri, in University of Maine collection, apparently of same series as those recorded by Leonard].

Myzus carthusianus Haviland, 1918:49–50 [type: Godalming, Surrey, England, on thistle].

Capitophorus carthusianus (Haviland).—J. Davidson, 1925:18.—Theobald, 1926:256.—Patch, 1938:244.

Capitophorus cirsii Nevsky, 1928:195 [types: Tashkent, Fergaria, Djar-Kurgan, Fettchenko in Middle Asia, on Cirsium arvense, Carduus spp., Arctium majus (data given in original description)].—Nevsky, 1929:139–140.—Patch, 1938; 244.

Capitophorus cynariella Theobald, 1923a:39–42 [type: Gizeh, Egypt, on Cynara scolymus].—Patch, 1938:244.

Capitophorus flaveolus Walker.—Glendenning, 1929:56.—Hottes and Frison, 1931:282–283.—Leonard, 1936:180.

Capitophorus n. sp. (Laing) [sic].—Ogilvie, 1928:22 [on Cynara cardunculus].

DIAGNOSIS.—Apterous vivipara can be separated from other thistle aphids as follows: (1) from the European C. carduinus, by its more acutely tapered cauda, presence of more caudal hairs (7–13, m = 10.4, n = 40 vs. 5–6, m = 5.6, n = 3), larger proportion of unguis to base of a.s.VI (5½–9 times, m = 7.09, n = 51 vs. 4¾–6 times, m = 5⅓, n = 4), and the darkened tips of cornicles; and (2) from C. horni, by the 1–1–1 chaetotaxy of metathoracic to sixth abdominal segments, and also the dark tips of cornicles. Among alate females, C. elaeagni differs from both C. carduinus and C. horni by having consistently more sensoria on a.s.III (37–60, m = 43.5, n = 68 vs. 29–35, m = 30.9, n = 12 for C. carduinus, and 21–33, m = 27.0, n = 10 for C. horni) and greater ratio of unguis to base of a.s.VI (averaging 7¾ vs. 5¼ and 5¾, respectively); further from C. carduinus by always bearing sensoria on a.s.V (2–14, m = 7.4, n = 60 vs. 0–4, m = 1.0, n = 12), and from C. horni by its anterior abdominal chaetotaxy (1–1–1 vs. 2–1–2). On the primary host, apterous and alate fundatrigeniae can be recognized from those of said species by same characters given for viviparous exules.

DESCRIPTION.—Fundatrix and Apterous Fundatrigeniae: Much like apterous exule except for shorter unguis; unique among Capitophorus species in that a.s.IV and V are separate, dorsal seta of a.s.II usually present.

Measurements (in mm) of 10 specimens on Elaeagnus (from Gainesville, Florida, 14–II–1940; Urbana, Illinois, 9–V–1929; St. Paul, Minnesota, 2–VI–1966 and 20–IV–1968; and Sturgeon Bay, Wisconsin, 4–V–1925): BL 1:28–1.82 (1.61), We .33–.41 (.38); a.s.III .22–.38 (.312), a.s.IV .16–.33 (.233), a.s.V .17–.27 (.221), a.s.VI .08–.11 (.094) + .36–.73 (.566); cornicles .40–.73 (.591), cauda .15–.25 (.216); hind tibiae .69–1.03 (.885), hind ta–2 .07–.10 (.089), and rostrum IV+V .12–.15 (.138). Spinal setae of abd.s. I–V .0110–.0440 (.0292), pleurals I–V .0088–.0308 (.0175); mf .0264–.0550 (.0387), lf .0352–.0572 (.0457), df–1 .0374–.0550 (.0468), df–2 .0110–.0484 (.0305), ipf .0110–.0440 (.0296), and opf .0088–.0374 (.0247). Proportions of a.s.III:IV:V, 1: .64–.92 (.74): .61–.75 (.71); a.s.VIu/VIb 2.33–7.56 (5.88); co/ca 2.44–3.23 (2.74); and rostrum IV+V/ hind ta–2 1.40–1.88 (1.59).

Alate Fundatrigeniae: Similar to alate exules except for slightly shorter unguis.

Measurements (in mm) of 10 specimens on Elaeagnus (all from St. Paul, Minnesota, 2–VI–1966): BL 1.59–1.81 (1.69), We .35–.40 (.376); a.s.III .39–44 (.415), a.s.IV .29–.33 (.312), a.s.V .23–.28 (.248), a.s.VI .09–.12 (.099) + .52–.77 (.693); cornicles .42–.47 (.446), cauda .10–.13 (.113); hind tibiae 1.06–1.14 (1.09), hind ta–2 .09–.10 (.096), and rostrum IV+V .12–.13 (.128). Proportions of a.s.III:IV:V, 1: .69–.85 (.75): .55–.65 (.60); a.s.VIu/VIb 5.2–8.11 (6.99); and co/ca 3.38–4.6 (3.97).

Apterous Viviparous Female (exule): Head with normal complement of setae, i.e., mf 1p, lf 1p, vlf 1p, df 4p, vf 2p, ac usually 6, and md 1–6 (usually 3 or 4) on each side; proportions of dorsal setae variable but anterior ones (mf, lf and df–1) always longest, df–2 shorter than df–1 (about ⅔ among apterae on Cirsium and Sonchus, see Figures 77, 78) or subequal to it (specimens on Cynara, Figure 80), posterior df’s ⅓ to ⅔ df–1 among Cirsium specimens, and ¾ to equal df–1 among those on Cynara; dorsal setae capitate, ventral setae with all but ac, pc, and md also knobbed. Antennal segment I with 5–9 (usually 6) knobbed setae aside from small pointed one on dorsum; a.s.II with knobbed setae; a.s.IV about ¾ and a.s.V about ⅔ the length of a.s.III; unguis of a.s.VI 5½ = 9 times (m = 7.09, n = 51) as long as base.

Prothorax with 8 setae arranged in two transverse rows of 4; mesothorax with 1 or 2 spinal, 1 pleural, and 1 or 2 marginal setae; metathorax with same pattern as abd.s. 1–5, namely, 1–1–1; abdominal marginals sometimes partly duplicated, this being more frequent among specimens on Cynara (e.g., 68% of 79 specimens had at least one duplication) than those on Cirsium; on tapered posterior segments, setal bases close together, 2 or 3 longer ones present on either side of median line, and 2 or 3 smaller outer ones. Spinal setae variable in length: .0088–.0286 (m = .0166, n = 95) in some Cirsium-collected specimens from Minnesota (Figure 77), .0176–.0440 (m = 0.294, n = 89) in another clone on same host and locality (Figure 78), and .0264–.0704 mm (m = .0513, n = 96) in specimens on Cynara from California; first type about ½, second equal to, and third 1½ times basal diameter of a.s.III. Pleural setae always shorter than spinals, ½ to ⅔ their lengths, and ⅓ to ½ basal diameter of a.s.III among specimens on Cirsium and Sonchus, or up to ¾ or equal this diameter among Cynara specimens. Cauda tapering to acute point; with 7–13 (m = 10.4, n = 40) setae, 2–4 pairs lateral and longer than those on posterodorsal surface. Cornicles cylindrical, imbricate, tips brown, and 2½ to 3⅓ times cauda in length. Rostrum IV+V rostrate; with 1 basal, 1 dorsal, and 3 lateral pairs of setae, ml distinctly removed from pl setae and all lateral setae subequally small.

Measurements (in mm) of 10 specimens on Cirsium (from St. Paul, Minnesota, 4 to 8–IX–1966): BL 1.67–1.85 (1.78), We .37–.40 (.39); a.s.III .35–.45 (.403), a.s.IV .30–.40 (.362), a.s.V .26–.32 (.289), a.s.VI .09–.11 (.099) + .70–.80 (.735); cornicles .68–.83 (.745), cauda .24–.30 (.272); hind tibiae .90–1.12 (1.04), hind ta–2 .08–.09 (.089), and rostrum IV+V .125–.14 (.136). Proportions of a.s.III:IV:V, 1: .80–1.00 (.89): .66–.79 (.72); VIu/VIb 6.45–8.82 (7.57); co/ca 2.48–3.32 (2.75); and rostrum IV+V/ hind ta–2 1.38–1.75 (1.52). Length of head setae: mf .0286–.0528 (.0386), If .0396–0550 (.0447), df–1 .0330–.0484 (.0439), df–2 .0132–.0396 (.0314), ipf .0110–.0308 (.0200), and opf .0110–.0264 (.0184).

Alate Viviparous Female (exule): Head, thorax, antennae except extreme bases of a.s.III, and abdominal sclerites brown; legs pale like membranous portions of abdomen but darker on distal ⅓ to ½ of femora, tips of tibiae and entire tarsi; rostrum IV+V, tips of cornicles, and wing veins brown. Head and abdominal chaetotaxy similar to apterous female but setae much shorter and merely blunt or pointed. Cauda variably shaped (Figures 88–90) but always with constriction before anterolateral pair of setae; with 2 or 3 lateral pairs and 1 posterodorsal setae. Cornicles and rostrum IV+V as in aptera except for size.

Measurements (in mm) of 20 specimens on Cirsium (from St. Paul, Minnesota, 26–VIII to 4–IX–1966): BL 1.50–1.98 (1.79), We .34–.38 (.362); a.s.III .40–.50 (.443), a.s.IV .31–.39 (.349), a.s.V .25–.31 (.277), as.VI .09–.11 (.101) + .68–.83 (.768); cornicles .40–.56 (.486), cauda .11–.18 (.148); hind tibiae .97–1.23 (1.10), hind ta–2 .08–.10 (.090), and rostrum IV+V .11–.14 (.128). Sensoria on a.s.III 37–51 (44.3), on a.s.IV 17–37 (26.8), and on a.s.V 2–14 (7.3).

Gynopara: Like the summer alatae except for presence of more sensoria on a.s.III–V. Counts of sensoria for 10 specimens on Elaeagnus (from Minneapolis, Minnesota, 20–X–1927 and 21–X–1928): 46–66 (53.4) on a.s.III; 24–42 (35.5) on a.s.IV; and 7–15 (11.5) on a.s.V.

Oviparous Female: Similar to other apterous morphs but smaller; dorsal seta of a.s.II frequently absent; dorsal setae shorter, more slender, eighth abdominal marginals sometimes pointed; cauda shorter, stouter; subgenital plate with more numerous, all pointed setae; basal portion of hind tibiae swollen, bearing numerous pseudosensoria.

Measurements (in mm) of 8 specimens on Elaeagnus (from Fort Collins, Colorado, 21–X–1909; Minneapolis, Minnesota, 11–X–1928; and St. Paul, Minnesota, 1–XI–1961) and 5 specimens on Hippophae (from Minnesota State Farm, 3–XI–1899): BL 1.34–1.73 (1.46), We .35–.40 (.368); a.s.III .21–.33 (.268), a.s.IV .16–.25 (.212), a.s.V .18–.25 (.216), a.s.VI .08–.10 (.092) + .19–.60 (.428); cornicles .38–.52 (.451), cauda .15–.19 (.168); hind tibiae .63–.74 (.700), hind ta–2 .07–.10 (.086) and rostrum IV+V .13–.15 (.139). Length of setae: abdominal spinals I–V .0132–.0352 (.0205), pleurals I–V .0088–.0198 (.0121); mf .0198–.0528 (.0379), If .0264–.0594 (.0429), df–1 .0286–.0550 (.0412), df–2 .0110–.0440 (.0243), ipf .0110–.0264 (.0165), and opf .0110–.0220 (.0143). Proportions of a.s.III:IV:V, 1: .67–.92 (.79): .67–.93 (.80); VIu/VIb 2.11–6.33 (4.51); co/ca 2.33–3.06 (2.73); and rostrum IV+V/ hind ta–2 1.44–2.0 (1.68).

Alate Male: Similar to alate female except as follows: head setae all pointed; antennae slightly longer, sensoria more numerous; spinopleural sclerites of third to fifth abdominal segments broken into transverse bars; cornicles and cauda relatively shorter. Genitalia illustrated in Figure 94; aedeagus oblong, with slightly angular apex.

Measurements (in mm) of 14 specimens on Cirsium (from Fort Collins, Colorado, 6–X–1914), Elaeagnus (from Fort Collins, Colo., 21–X–1909), and trap pans (from Union Gap, Washington, X–and XI–1952 to 1953): BL 1.45–2.12 (1.87), We .34–.41 (.396); a.s.III .47–.59 (.519), a.s.IV .37–.49 (.427), a.s.V .32–.41 (.366), a.s.VI .10–.14 (.119) + .59–.96 (.861); cornicles .36–.46 (.409), cauda .10–.14 (.123); hind tibiae 1.07–1.32 (1.17), hind ta–2 .08–.10 (.093), and rostrum IV+V .12–.14 (.133). Proportions of a.s.III:IV:V, 1: .76–.92 (.83): .66–.76 (.70); VIu/VIb 5.86–8.0 (7.23); co/ca 2.86–3.91 (3.35); and rostrum IV+V/ hind ta–2 1.30–1.75 (1.44). Number of sensoria on a.s.III 56–83 (66.3), a.s.IV 39–63 (46.6), and a.s.V 16–29 (22.8).

HOSTS (references to quoted hosts in parentheses).—Winter hosts: Elaeagnus angustifolia, E. commutata, E. longipes (Patch, 1938), E. multiflora (Leonard, 1956), E. oldhami (Takahashi, 1931, in Formosa), E. pungens, E. umbellata (Leonard, 1964); Hippophae rhamnoides; and Shepherdea argentea.

Summer hosts: Arctium lappa; Carduus crispus, C. leptacanthus (Eastop, 1958, in East Africa), C. tenuiflorus (Cottier, 1953, in New Zealand); Cirsium arvense, C. horridulum, C. japonicum (Takahashi, 1931, in Formosa), C. lanceolatum, C. mexicanum (Smith, Martorell, and Escolar, 1963, in Puerto Rico), C. nuttallii, C. occidentalis, C. smallii, C. vulgare; Cnicus sp., Cryptostemma calendulaceum (Cottier, 1953, in New Zealand; and Eastop, 1966, in Australia); Cynara cardunculus, C. scolymus; Silybium marianum (Cottier, 1953, in New Zealand); and Sonchus arvensis.

DISTRIBUTION.—Capitophorus elaeagni has been recorded from all zoogeographical regions of the world.

SPECIMENS EXAMINED.—Numerous nearctic specimens of all morphs and stages from various localities including: CANADA: Manitoba, New Brunswick, Nova Scotia and Ontario, UNITED STATES: California, Colorado, Florida, Hawaii, Idaho, Illinois, Indiana, Kansas, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Missouri, Montana, New Hampshire, New Jersey, North Carolina, North Dakota, Oregon, Pennsylvania, Texas, Utah, Washington, Washington, D.C., and Wisconsin. Specimens from the following countries also seen: Argentina, Brazil, Chile, China, Egypt, Italy, Japan, Netherlands, and Turkey. Specimens of C. carduinus include 8 apt.v.f., 8 al.v.f., 11 ovip.f., and 4 al.m. from England, Germany, and Netherlands.