Pleotrichophorus knowltoni Corpuz-Raros & E. F. Cook 1974

Pleotrichophorus knowltoni

DIAGNOSIS.—This species resembles P. chrysanthemi and P. glandulosus in its moderately long cornicles (averaging between .45 and .55 mm); acutely pointed last rostral segment; and long, thin stemmed, apically flattened head and body hairs. It differs from both species in a much denser cover of setae (mean df setae of oviparous females number 26.67 ± 3.16, n = 6 vs. 13.36 ± .64, n = 22 in P. chrysanthemi and 13.89 ± .48, n = 49 in P. glandulosus apterous vivipara) and from P. glandulosus in its thinner-stemmed setae.

DESCRIPTION.—Apterous Viviparous Female (based on holotype only): Color in life unknown; cleared, stained specimen with body pale, tips of rostrum and tibiae, and entire tarsi dark brown, antennae dusky from basal ¼ of third segment (other segments missing), cornicles dusky from about distal ⅓. Body length 2.47, width across eyes .32 mm. Head with moderately developed mesoand laterofrontal tubercles; mf 1p plus 1 unpaired one, lf 2 and 3 on each side, vlf 1p, df 26, vf 7, pc 2p, ac 4, and md 3 and 4 on each lobe; distally flattened or expanded dorsal setae with long (about 5/6 of length for mf and df–1) slender (about 33 μ wide) stems; vf and vlf much like df setae but pc, ac, and md blunt or pointed at apices; mf .0506–.0638 and df–1 .0484 mm long. Antennal segment I produced on inner distal margin, imbricate with 7–8 blunt or spine-like setae in addition to basal pointed one on dorsum. A.s.II imbricate, with blunt or pointed setae. A.s.III imbricate, with mostly pointed setae, longest slightly more than ½ basal diameter of segment, with 2 sensoria on both sides; remainder of flagellum broken.

Dorsal integument smooth on disk, becoming imbricate-spiculate caudad from abd.s. 6; with 2 rows of small pleural intersegmental patches; setae of similar shape to those on head, with posterior slightly longer than discal ones. Subgenital plate with mostly marginal setae (Figure 289). Cauda .27 mm long; stoutly elongate, with rounded tip; spiculate; with 2 lateral pairs and 2 posterodorsal setae. Cornicles .47 mm long, 1¾ times as long as cauda; cylindrical, with slightly incrassate bases; imbricate, wrinkled and armed with small pointed teeth. Legs with 3, 3, 3 hairs on first tarsal joints; hind tibiae 1.39 and hind ta–2 .15 mm long. Rostrum IV+V .13 mm long; tapering to acute point, with straight margins; with 1 basal, 2 dorsal, and 3 lateral pairs of setae, ml and pl ⅓ to ¼ al in length.

Oviparous Female: Very much like apterous vivipara, differing only as follows: body setae thinner, less expanded, some of posterior setae pointed (Figure 291); subgenital plate (Figure 290) more thickly armed with pointed setae; hind tibiae thickened, bearing pseudosensoria on basal third.

Measurements (in mm) of 6 paratypes: B.L. 2.13–2.47 (2.24), We .49–.56 (.530); a.s.III .57–.70 (.623), a.s.IV .42–.63 (.538), a.s.V .48–.57 (.532), a.s.VI .15–.17 (.16) + .86–.98 (.94); cornicles .43–.51 (.466), cauda .22–.27 (.238); hind tibiae 1.30–1.59 (1.37), hind ta–2 .13–.16 (.146), rostrum IV+V .13–.14 (.133); mf .0440–.0638 (.0527), and df–1 .0462–.0660 (.0564). Proportions of a.s.III:IV:V. 1: .71–.98 (.88): .77–.92 (.86); VIu/VIb 5.38–6.13 (5.84); co/ca 1.78–2.05 (1.96 ± .06); rostrum IV + V/ hind ta–2 .87–1.00 (.91). Number of sensoria on a.s.III 1–4 (2.3); df setae 23–32 (26.67 ± 3.16), and posterodorsal setae 2–5 (3.7).

HOST.—Unknown.

DISTRIBUTION.—No records other than type-locality (Umiat, Alaska).

TYPES.—Holotype, apt.v.f., Umiat, Alaska, 24–VII–1955, R.F. Smith, on unknown host; specimen at 5:00 o’clock on type-slide. Paratypes: 6 ovip.f., with same data as holotype and 3 of which are mounted on same slide as holotype. Holotype and all paratypes in EOE coll.

ETYMOLOGY.—This species is named in honor of Dr. George F. Knowlton, Professor emeritus, Utah State University.