Pleotrichophorus filifoliae (Palmer & M. A. 1938)

Pleotrichophorus filifoliae (Palmer)

Capitophorus filifoliae Palmer, 1938:355 [type: apt.v.f., Denver, Colorado, 27–VIII–1919, LCB, on Artemisia filifolia; USNM 52349]; 1952:255–256.

Pleotrichophorus filifoliae (Palmer).—Hille Ris Lambers, 1966:606; 1969:166.

DIAGNOSIS.—A rather small species (1–1.23 mm long), P. filifoliae can be recognized by its short cornicles (.08–.12, m = .091, n = 11) that are about half (.50 ± .05) the length of the cauda, the short (.09–.10, m = .097, n = 6), slender acutely pointed but not needle-like last rostral segment, and the rather long (mf and df–1 setae .0352–.0462 mm), distinctly stemmed and funnel-shaped head and body setae. It resembles P. obscuratus in the shape of setae but can be readily separated from it by the pale legs and cornicles and by the shape of the last rostral segment (distinctly needle-tipped in P. obscuratus).

DESCRIPTION.—Apterous Viviparous Female: Color in life medium green, appearing frosted due to funnel-shaped setae (Palmer, 1938); cleared specimens pale with the tips of a.s.V, remainder of antennae, tips of tibiae, entire tarsi and most of rostrum IV+V darker. Body 1.08–1.23 (1.14, n = 5) mm long, .30–.38 (.335, n = 8) mm wide across eyes. Head with moderately produced latero- and mesofrontal tubercles; mf 2p, lf 2–3 on each side, vlf 1p, df 21–27 (23.43 ± 1.50, n = 7), vf 5–7, pc 2p, ac 4, and md 2–4 (usually 3) on each side; dorsal setae funnel-shaped, with distinct stems, about % entire length for anterior or ⅓ to ½ for posterior setae; ventral setae with vf and vlf similarly but more narrowly funnel-shaped, remainder pointed or blunt at apices; mf and df–1 setae .0352–.0462 mm long, with means of .0389 (n = 14) and .0413 (n = 13), respectively. Antennal segment I slightly produced on inner distal margin, faintly imbricate, with 5–9 blunt or slightly knobbed setae aside from usual pointed seta on dorsum. A.s.II usually with blunt or knobbed setae. A.s.III faintly imbricate, setae blunt or knobbed, rather small, longest less than ½ basal diameter of segment, with 1 sensorium in all 14 segments counted. A.s.IV and V subequally long ¾ to equal a.s.III in length; a.s.VI with unguis 4⅓ to 5⅓ times (4.68, n = 7) as long as base (about 3 times in one spring-collected female seen).

Dorsal body integument smooth on disk, becoming spiculate caudally; setae moderately dense and of similar shape to those on head. Cauda .17–.18 (.178, n = 5) mm long; elongate, with slight basal constriction, acutely rounded apex; slightly dusky; spiculate; with 2 lateral pairs and 1 posterodorsal setae. Cornicles .08–. 12 (.091, n = 11) mm long, .44–.53 (.50 ± .05, n = 5) times as long as cauda; cylindrical; apices slightly dusky; imbricate-spiculate, spicules rather small but sharp. Legs with 3, 3, 3 hairs on first tarsal joints; hind tibiae .60–.70 (.674, n = 10) and hind ta–2, .09–.11 (.10, n = 10) mm long. Rostrum IV+V .09–.10 (.097, n = 6) mm long, .91–1.11 times (.96 ± .06, n = 9) length of hind ta–2; slender at base, tapering gradually to acute point, distal ¼ to ⅓ past pl setae sometimes appearing as stout “needle”; with 1 basal, 2 dorsal, and 3 lateral pairs of setae, al about 2 times size of ml and pi setae.

Measurements (in mm) of holotype: BL 1.21, We .35; a.s.III–V all .30, .25, and .25 on both sides, a.s.VI .12 + .59 and .11 + .58; cornicles both .09, cauda .18; hind tibiae (one side) .74, hind ta–2 missing, and rostrum IV+V .10.

Alate viviparous female: Not seen. Palmer (1938) gives the following measurements for one specimen: BL 1.4; a.s.III .37, a.s.IV .27, a.s.V .28, a.s.VI .12 + .50; hind tibiae .72, hind ta–2 .10 mm. Number of sensoria on a.s.III 10.

Sexuales: Not known.

HOST.—Artemisia filifoliae.

DISTRIBUTION.—Apparently rare, and so far known only around type-locality (Denver, Colorado).

SPECIMENS EXAMINED.—Holotype: 1 paratype slide containing 8 apt.v.f. and with same data as holotype (CSU); and 1 “metatype” apt.v.f., Roggen, Colorado, 13–V–1939, MAP, on Artemisia filifolia.