Pleotrichophorus gregarius (Knowlton 1929)

Pleotrichophorus gregarius (Knowlton)

Capitophorus gregarius Knowlton, 1929:13 [lectotype: apt. v.f., Logan Canyon, Utah, 6–X–1927, GFK, on Chrysothamnus nauseosus; in EOE coll.].—Knowlton and Smith, 1936a:110; 1937:151.—Knowlton, 1948:122.—Palmer, 1952: 258.

Pleotrichophorus gregarius (Knowlton).—Hille Ris Lambers, 1969:167.

DIAGNOSIS.—This species very closely resembles P. xerozoous from which it differs by its more slender, longer, gradually tapered, larger rostrum IV+V/ hind ta–2 ratio (Figure 128 vs 127). Furthermore, the head and body setae are generally longer, more narrowly expanded (Figures 185–187, 190), at least the anterior head setae are petiolate, and there are more sensoria on a.s.III. (See diagnosis and notes under P. xerozoous for further details of differences).

DESCRIPTION.—Apterous Viviparous Female: Color in life dark brown to chocolate brown in spring forms and brown to greenish brown in summer and fall forms (Knowlton, 1929); cleared specimen pale, with last 2 rostral segments, tips of a.s.III and IV, areas around secondary sensoria, most of a.s.V and entire a.s.VI, bases and apices of tibiae, entire tarsi and distal ½ to ⅔ of cornicles brown. Body length 1.85–2.69 (2.33, n = 88), width across eyes .48–.58 (.534, n = 98) mm. Laterofrontal tubercles moderately produced, mesofrontal tubercle rather small; mf 1p, lf 2–4 on each side, vlf 1p, df 13–21 (16.28 ± .28, n = 98), vf 7–15 (10.48, n–94), pc usually 2p, ac 4–7, md 2–6 on each plate; dorsal setae basically funnel-shaped, anterior ones usually slightly expanded, posterior ones shorter, less distinctly stemmed; ventral setae except vlf and some of vf’s elongate, with blunt or pointed apices; mf .0176–.0462 (.0362, n = 194) and df–1 .0220–.0484 (.0372, n = 195) mm long. Antennal segment I produced on mesodistal margin, faintly imbricate with 10–22 (usually 12 or 13) blunt or knobbed setae aside from basal pointed one on dorsum. A.s.II normally with blunt or knobbed setae. A.s.III with short setae, longest about ½ basal diameter of segment and all setae of same shape as those of preceding segment; bearing 2–9 (4.72, n = 185) sensoria. A.s.IV and V about as long as a.s.III; unguis averaging 4 to 7 times (5.60, n = 100) base of a.s.VI.

Dorsal body integument smooth on disk, becoming faintly striate-spiculate caudally; with 2 median rows of papillae bearing 2–5 spinal setae each, papillae increasingly developed posteriorly, similar pleural projections also present but less conspicuous than spinal; dorsal setae of same shape as those on head but generally more expanded. Cauda stoutly elongate, not constricted, with rounded apex; spiculate; with 3–5 (3.91, n = 196) setae on each side and 0–6 (3.00, n = 98) on posterodorsal surface. Cornicles .42–.77 (.574, n = 194) mm long, 1¼ to 2 times (1.61 ± .10, n = 100) as long as cauda; cylindrical, with bases and apices slightly thickened; rather conspicuously imbricate-spiculate. Legs with 3, 3, 3 hairs on first tarsal joints. Rostrum IV+V slender at base and tapering to acute point; .10–. 12 (.109, n = 195) mm long, .67–1.00 (.79 ± .02, n = 100) times length of hind ta–2; with 1 basal, 2 dorsal and 3 lateral pairs of setae, al about twice as long as ml and pi setae.

Measurements (in mm) of lectotype and 21 paralectotypes: BL 1.85–2.50 (2.17), We .49–.58 (.53); a.s.III .50–.70 (.612), a.s.IV .35–.74 (.601), a.s.V .45–.73 (.589), a.s.VI .12–.19 (.153) + .72–.92 (.818); cornicles .41–.72 (.585), cauda .25–.40 (.344); hind tibiae 1.22–1.60 (1.43), hind ta–2 .12–.16 (.139) and rostrum IV+V .10–.12 (.111). Proportions of a.s.III: IV:V, 1: .64–1.14 (.97): .82–1.07 (.93); VIu/VIb 4.63–7.00 (5.63); co/ca 1.29–2.06 (1.69); rostrum IV+V/ hind ta–2 .67–1.00 (.81).

Alate Viviparous Female: Not seen. Palmer (1952:258) gives the following measurements: BL 1.60, We .50; a.s.III .65, a.s.IV .73, a.s.V, .66, a.s.VI .16 + .83; cornicles .55 and hind tibiae 1.55 mm. Number of sensoria on a.s.III 12–15.

Oviparous Female: Resembles apterous vivipara except as follows: dorsal setae less expanded; spinal pleural papillae less conspicuous; cauda shorter, stouter, saclike, darker; subgenital plate bearing more setae; hind tibiae with basal half thickened, bearing numerous pseudosensoria.

Measurements (in mm) of 5 paralectotypes: BL 1.95–2.25 (2.12), We .50–.55 (.52); a.s.III .52–.62 (.587), a.s.IV .48–.59 (.526), a.s.V .49–.55 (.531), a.s.VI .13–.16 (.143) + .76–.90 (.820); cornicles .39–.48 (.427), cauda .23–.25 (.246); hind tibiae 1.20–1.37 (1.30), hind ta–2 .12–.14 (.135), rostrum IV+V .11–.12 (.113); mf .0286–.0440 (.0360) and df–1 .0308–.0484 (.0403). Proportions of a.s.III: IV:V, 1: .81–.98 (.89): .87–.96 (.91); a.s.VIu/VIb 5.43–6.00 (5.76); co/ca 1.50–1.92 (1.73); rostrum IV+V/ hind ta–2 .79–.92 (.84). Number of sensoria on a.s.III 3–8 (4.67); df setae 14–19 (16.2); lateral caudal setae 3–6 (4.5) and posterodorsal caudal setae 2–6 (4.0).

Alate Male: Dark brown except membranous portions of abdomen and wings pale. Differs morphologically from apterous viviparous female in having fewer df setae (8–13, m = 10.58, n = 12), these merely blunt or pointed; setae shorter, mf .0176–.0286 (.0222, n = 18), df–1 .0220–.0330 (.0276, n = 21) mm long; antennal setae also blunt or pointed; more sensoria on a.s.III (34–53, m = 42.73, n = 22), also present on a.s.IV (18–32, m = 24.57, n = 21) and on a.s.V (15–27, m = 21.71, n = 21); abdominal segments 1 to 6 with 2 large, transverse pleural sclerites (may be broken on some segments), 2 dashlike spinal and 2 ovate marginal sclerites, and spinopleural areas of abd.s. 7 and 8 also sclerotized; cauda shorter, more slender, darker; cornicles (.18–.39 mm, m = .258, n = 24), cauda (.14–. 19 mm, m = .1.67, n = 12) both shorter so co/ca ratio about same (1.20–2.14, m = 1.58, n = 24). Genito-anal capsule dark brown, aedeagus cylindrical, with rounded apex, parameres rather small, setaceous lobes.

Measurements (in mm) of 3 paralectotypes: BL 1.70–1.98 (1.84), We .39–.45 (.427); a.s.III .61–.71 (.655), a.s.IV .55–.64 (.587), a.s.V .52–.61 (.560), a.s.VI .13–.15 (.14) + .80–.89 (.845); cornicles .18–.25 (.232), cauda .14–.17 (.153); hind tibiae 1.22–1.50 (1.33), hind ta–2 .12–.14 (.132) and rostrum IV+V. 10–. 12 (.107). Proportions of a.s.III:IV;V, 1: .85–.98 (.89): .80–.95 (.86); VIu/VIb 5.64–5.71 (5.67); co/ca 1.20–1.79 (1.52); rostrum IV+V/ hind ta–2 .77–86 (.81).

HOSTS.—Chrysothamnus nauseosus and C. viscidiflorus (Palmer, 1952).

DISTRIBUTION.—Widely distributed in Utah and also recorded from California, Idaho, Nevada, and Oregon.

TYPES (designated from available cotypes).—Lectotype, apt.v.f. with data given above. Paralectotypes: 5 apt.v.f., 5 ovip.f., 3 al.m., 8 apt.ny., and 1 altd.ny., with same data as lectotype (12 slides in EOE coll. and 6 slides in GFK coll.); 6 apt.v.f., Brigham Canyon, 10–VIII–1927, GFK, on Chrysothamnus nauseosus (EOE coll.); 5 apt.v.f. and 3 apt.ny., Wellsville Canyon, Utah, 2–IX–1927, GFK on C. nauseosus (EOE coll.); and 5 apt.v.f. and 3 apt.ny., Immigration Canyon, Idaho, 10–IX–1927, GFK, on C. nauseosus (EOE coll.).

SPECIMENS EXAMINED.—Aside from types, numerous specimens of all morphs, except alate viviparae, from following localities: C ALIFORNIA: Big Bear City, Big Bear Lake, Fish Springs (Inyo Co.), Lebec (Kern Co.) Mojave Desert, and 3 mi E Onion Valley (Inyo Co.). I DAHO: Franklin. N EVADA: Reno. O REGON: Warm Springs. U TAH: Blacksmith Fork Canyon, Box Elder Canyon, Cottonwood Canyon, Dry Lake, Farmington, Hyde Park, Hyrum Dam State Park, Logan Canyon, Logan Dry Canyon, Logan Green Canyon, Mantua, Monticello, North Neola, Ogden Canyon, Paradise, Pine Valley, Salt Lake City, Smithfield Canyon, Spring Hollow, Uinta, Weber Canyon, and Wellsville Canyon.

Pleotrichophorus heterohirsutus (Gillette and Palmer)

Capitophorus heterohirsutus Gillette and Palmer, 1933:351 [type: apt.v.f., Sheep Creek, Northern Larimer Co., Colorado, 17–IX–1932; USNM 49297]; 1934:151.—Knowlton and Smith, 1936b:231.—Patch, 1938:245.—Palmer, 1952:259.

Pleotrichophorus heterohirsutus (Gillette and Palmer).—Hille Ris Lambers, 1953:115; 1966:606; 1969:165, 167.

Capitophorus bitrichus Knowlton and Smith, 1936b:230 [originally described from apt.v.f., Bear Canyon, Bradshaw Ranch in Sardine Canyon, Lewiston and Logan, Utah, 4 to 14–VIII–1925, GFK, on Artemisia; type in USNM; “paratypes” from Logan, CFS coll., seen].—Knowlton, 1941:138.—Palmer, 1952:251.

Pleotrichophorus bitrichus (Knowlton and Smith).—Hille Ris Lambers, 1966:606; 1969:165, 172 [as a synonym of P. heterohirsutus (Gillette and Palmer)].

DIAGNOSIS.—P. heterohirsutus is a small, pale green aphid that can be easily recognized by its short cornicles, needle-tipped last rostral segment, broadly convex frontal margin or poorly developed laterofrontal tubercles, and the mixture of pointed and conical- to fan-shaped setae on the dorsum of the head (especially the anterior setae) and the body (especially the posterior abdominal segments). The larger members (B.L. up to 1.80 mm) may be confused with smaller, pale-legged specimens of P. quadritrichus pallidus; but can be separated from them by the frontal and setal characters, by its pale, triangular and usually pointed cauda (vs. oblong, distinctly constricted and broadly rounded cauda), and its much shorter, conical or fan-shaped anterior head setae (vs. elongate, cylindrical anterior head setae with blunt or flattened apices).

DESCRIPTION.—Apterous Viviparous Female: Color in life pale green, appearing frosted (Gillette and Palmer, 1933). Cleared specimen with pale body; antennae commonly dark from apices of a.s.V but in some individuals, dark from apices of a.s.IV (e.g., from Allen and Green Canyon, Utah) or even distal half of a.s.IV or apices of a.s.III (e.g., from Uinta Mts., Utah); legs pale, with dusky tibial apices or sometimes bases of tibiae also brown (e.g., Green Canyon and Uinta Mts., Utah), entire tarsi dark brown; rostrum with most of last segment dark brown, sclerotic; apices of cornicles light brown or dusky, or entirely dusky (e.g., specimens from Uinta Mts.). Body 1.06–1.82 (1.36, n = 17) mm long, .29–.43 (.368, n = 19) mm wide across eyes. Head with broadly convex frontal margin, laterofrontal tubercles barely (Figures 388, 392) or slightly (Figures 396, 398) produced; mf setae usually 2p (1 or 2 sometimes added, ventrally displaced, in which case rather difficult to distinguish from vf’s), lf 1–3 (usually 2) on each side, vlf 1p, df 26–49 (39.32 ± 3.13, n = 19), vf 6–15 (usually 12), pc 2p, ac 3–7 (usually 4), md 2–4 (usually 3) on each plate. Dorsal head setae a mixture of elongate, pointed (commonly If, sometimes mf, and less commonly some of df’s), elongate and blunt or flattened (mf, df–1, some of anterior df’s) and shorter, funnel- to fan-shaped ones (posterior df’s); ventral setae most commonly elongate, pointed but some vf's may be funnel- or fan-shaped. Antennal segment I only slightly produced mesally, almost smooth, with 3–6 long pointed setae in addition to usual small pointed one or dorsum. A.s.II with long, pointed setae. A.s.III faintly imbricate, with long pointed to blunt setae, longest subequally as long as basal diameter of segment, with 0–3 (1.03, n = 37) sensoria. A.s.IV and V subequal and ⅔ to ¾ length of a.s.III; unguis of a.s.VI 2½ to 4 ⅓ times (3.44, n = 32) as long as its base.

Tergum smooth, membranous, becoming finely spiculate caudally; with rather dense cover of funnel- to fan-shaped, and sometimes also a few pointed setae. Cauda .11–.25 (.156, n = 18) mm long; basically triangular, with acute, pointed or rounded apex, in most specimens not distinctly constricted; with 2 lateral pairs and 1 posterodorsal setae. Cornicles .12–.29 (1.86, n = 38) mm long, .92–.1.45 (1.19 ± .02, n = 36) times length of cauda; cylindrical; imbricate-spiculate. Legs with 3, 3, 3 hairs on 1st tarsal joints; hind tibiae .48–.91 (.636, n = 34), hind ta–2 .10–.14 (.II9, n = 34) mm long. Rostrum IV+V .13–.16 (.139, n = 19) and 1.00–1.40 times (1.18 ± .03, n = 34) as long as hind ta–2; slender, distal half, beyond pi setae, produced into thin cylindrical needle; with 1 basal, 2 dorsal, and 3 lateral pairs of setae, al about twice ml and pi setae in length.

Measurements (in mm) of 12 specimens from Wyoming: BL 1.06–1.37 (1.21), We .29–.40 (.349); a.s.III .21–.31 (.251), a.s.IV .14–.23 (.181), a.s.V .15–.22 (.190), a.s. VI .09–.11 (.103) + .25–.41 (.333); cornicles .12–.20 (.158), cauda .12–.16 (.134); hind tibiae .48–.68 (.573), hind ta–2 .10–.12 (.113), and rostrum IV+V .13–.14 (.136). Proportions of a.s.III:IV:V, 1: .64–.81 (.72): .65–.86 (.76); VIu/VIb 2.50–4.33 (3.42); co/ca .92–1.45 (1.17); rostrum IV+V/ hind ta–2 1.13–1.40 (1.21).

Measurements (in mm) of 4 “paratypes” of P. bitrichus: BL .98–1.28 (1.14), We .30–.37 (.340); a.s.III .19–.25 (.215), a.s.IV .12–.19 (.154), a.s.V .15–.18 (.166), a.s.VI .07–.11 (.101) + .26–.33 (.291); cornicles .11–.15 (.128), cauda .13–.16 (.143); hind tibiae .45–59 (.516), hind ta–2 .10–.11 (.108), and rostrum IV+V .12–.13 (.126). Proportions of a.s.III: IV:V, 1: .59–.81 (.69): .72–.84 (.76), and VIu/VIb 2.6–3.86 (2.93). Ratio of cornicles to cauda (including 10 other apt.v.f. from Hyrum, Utah) .85–1.18 (1.01 ± .03, n = 28); rostrum IV+V/ hind ta–2 1.09–1.33 (1.16 ± .02, n = 27); number of df setae 19–35 (25.11 ± 3.83, n = 9); number of sensoria on a.s.III 0–1 (.62, n = 26).

Alate Viviparous Female: Head, thorax, legs, except extreme bases of mid- and hind femora, and most of fore femora, antennae, wing veins and apical 2 rostral segments brown; abdomen and cauda pale, anal plate dusky, cornicles and disc of subgenital plate brown. Morphologically like apterous vivipara, differing only as follows: df setae fewer (11); a.s.III with more sensoria (8); abdominal setae relatively sparser. Abdominal sclerotizations not distinct in cleared specimen seen.

Measurements (in mm) of 1 specimen from Green Canyon, Utah: BL 1.78, We .40; a.s.III .45 (other segments missing on both sides); cornicles both .23, cauda .19; hind tibiae (one side only) 1.00, hind ta–2 .14, and rostrum IV+V .15.

Oviparous Female: Very much like apterous vivipara, including caudal shape (often stouter and shorter in other Pleotrichophorus species), differs from it in thickened tibial bases, bearing pseudosensoria on enlarged portion, and presence of more setae on subgenital plate.

Measurements (in mm) of 8 paratypes: BL 1.27–1.43 (1.35), We .35–.37 (.36); a.s.III .24–.32 (.279), a.s.IV .16–.20 (.180), a.s.V .17–.21 (.194), a.s.VI .09–.11 (.098) + .29–.36 (.323); cornicles .16–.19 (.17), cauda .13–.16 (.149); hind tibiae .57–.66 (.608), hind ta–2 .11–.12 (.114), and rostrum IV+V .12–.14 (.131). Proportions of a.s.III:IV:V, 1: .57–.71 (.65): .61–.75 (.71); VIu/VIb 2.91–3.67 (3.29); co/ca 1.00–1.21 (1.15); rostrum IV+V/ hind ta–2 1.08–1.23 (1.15). Number of df setae 29–35 (32); number of sensoria 0–1 (.7).

Apterous Male: Head dusky, faintly sclerotic; antennae brown except extreme bases of a.s.III; sternal and pleural apophyses, legs except bases of femora and mid portions of tibiae, last 2 rostral segments, cornicles and genito–anal capsule brown; body pale, membranous with 2 dusky brown pleural sclerites on metathorax to abd.s. 7, a second outer pair of smaller pleural thickenings on abd.s 3 to 5, less distinct and irregular spinal dashes and marginal thickenings around spiracles. Morphologically similar to apterous viviparous female except as follows: df setae fewer (15–20, m = 17, n = 4); more sensoria on a.s.III (22–30, m = 26.63, n = 8), also present on a.s.IV 8–16, m = 11.63, n = 8) and a.s.V (4–8, m = 5.5, n = 8); presence of sclerites on dorsum; body setae sparser, posterior segment bearing mostly elongate, pointed setae; cornicles shorter, co/ca ratio slightly smaller; cauda triangular, acutely pointed, not much extended beyond pi setae. Aedeagus short, thick, with truncate or slightly pointed apex; parameres small, setaceous.

Measurements (in mm) of 4 paratypes: BL 1.13–1.19 (1.16), We .30–.36 (.34); a.s.III .28–.31 (.296), a.s.IV .19–.21 (.199), a.s.V .18–.23 (.197), a.s.VI .09–. 11 (.099) + .29–.32 (.306); cornicles .07–.09 (.083), cauda .09–.10 (.095); hind tibiae .56–.59 (.573), hind ta–2 .11–.13 (.12), and rostrum IV+V .13. Proportions of a.s.III:IV:V, 1: .63–.72 (.67): .58–.77 (.66); VIu/VIb 2.90–3.56 (3.21); co/ca .78–.90 (.87); rostrum IV+V/ hind ta–2 1.00–1.18 (1.08).

HOSTS.—Artemisia tridentata, Artemisia sp.

DISTRIBUTION.—Colorado (northeastern), Utah (most records in northeastern and eastern portions), and Wyoming (southwestern).

SPECIMENS EXAMINED.—COLORADO: Eaton Res., No. Larimer Co., 10 ovip.f., 4 apt.m. and 6 ny., 17–IX–1932, MAP, on Artemisia tridentata (paratypes, C.S.U.). UTAH: Allen Canyon, 6 apt.v.f., 5–VII–1934, GFK, on A. tridentata (GFK coll.); Green Canyon, 1 apt.v.f., 1 al.v.f., and 2 ny., 5–VI–1953, GFK, on A. tridentata (GFK coll.); Uinta Mts., 2 apt.v.f., 4–VIII–1932, GFK, on Artemisia (CFS coll.). WYOMING: Douglas, 13 apt.v.f., 12–VIII–1929, on Artemisia (CSU).

Specimens of Capitophorus bitrichus examined: 4 apt.v.f., Logan, Utah, 12–VIII–1925, GFK, on sage brush (CFS coll.); and 9 apt.v.f. and 12 apt. ny., Hyrum, Utah, 23–VIII–1938, Knowlton and Hardy, on A. tridentata (CFS coll.).