Chilarboreus (s. str.) acuticollis Ruta, 2011

Ruta, Rafał & Yoshitomi, Hiroyuki, 2018, Description of females of Chilarboreus Ruta, 2011 (Coleoptera: Scirtidae: Scirtinae), Zootaxa 4388 (2), pp. 265-274 : 266-268

Chilarboreus (s. str.) acuticollis Ruta, 2011

( Figs 1A , 2 , 3A, 3D, 3F , 4 )

Material examined. 2 females (EUM): “ CHILI, Prov. Valdivia, \ Cerro Oncol , 6. II. \ 1999 T. Cekalovic leg. \ TC- 576 PO-5”.

Description. Female. Body elongate, widest in posterior 2/3 length of elytra, convex, sparsely clothed with procumbent setae ( Figs 1A , 2A ). Coloration light brown, without contrasting dorsal pattern. Head as long as wide, 1.2× wider than interocular space, convex, with small depression in posterior portion, covered with subtly granulate punctures; eyes small, subtly protuberant. Supraantennal ridge oblique ( Fig. 2E ), forming obtuse angle with anterior margin of clypeus; clypeus subtrapezoidal, with rectangular emargination in anterior portion. Antennae moderately long, extending to basal 1/4 of elytra; antennomere 1 globular, wide, antennomere 2 cylindrical, much narrower than antennomere 1, antennomere 3 long, ca. 1.4× longer than antennomere 2, antennomeres 4–10 gradually shortening, apical antennomere wide, suboval, as long as antennomere 3. Pronotum ( Fig. 2B ) rectangular, strongly transverse, sides subparallel, a bit wider at posterior angles, lateral carinae crenulate, antero- and posterolateral angles right-angled, not produced; disc convex, with deep longitudinal groove along the midline, deep fossae in anterolateral angles, and deep impunctate groove along basal margin ending in deep pits. Anterior portion of basal groove with two transverse, elevated, tubercle-like excitators, each with numerous minute punctures visible at high magnification ( Fig. 2C ). Punctation of pronotum granulate on disc, coarsely granulate on sides. Elytral punctation irregular, dense in anterior portion (punctures large, separated by ca. 0.5–0.7 diameter) and sparse in posterior portion (punctures small, separated by ca. 4.0 diameters). Each elytron with adsutural stria in anterior portion and with three distinct longitudinal carinae, humeral portion rounded. Anterolateral portions of elytra explanate and slightly produced anteriorly. Hind wings absent. Mesoventral process truncate at apex. Metaventrite with large, coarse punctures in anterior portion and almost smooth in posterior portion, with deep transverse groove along posterior margin ( Fig. 2D ). Abdomen with paired setal tufts on ventrite 4 ( Figs. 3A, D, F ). Sternite VIII elongate (L 0.64 mm), with a pair of subparallel apodemes fused basally; tergite VIII very long (L 1.30 mm), apical portion subtrapezoidal; ovipositor long (L 1.45 mm), branchlets absent, coxites membranous, triangularly elongate, not covered with setae, styli missing in the studied specimen ( Fig. 4A, B ). Bursal sclerite ( Fig. 4C ) small (L 0.45 mm), subconical, densely covered with spines.

Measurements and ratios. N=2: TL 2.01–2.33 (2.17), PL 0.50–0.53 (0.52), PW 0.77–0.80 (0.79), EL 1.67– 1.77 (1.72), EW 1.10–1.17 (1.14), TL/EW 1.8–2.0 (1.9), PW/PL 1.5, EL/EW 1.5, EL/PL 3.3.

Figures

FIGURE 1. Females of Chilarboreus, habitus: A) Ch. acuticollis; B) Ch. fossulatus (digitally reconstructed—left elytron missing in the specimen); C) Ch.darwini. Scale bar = 1 mm.

FIGURE 3. Chilarboreus, female abdomens: A) Ch. acuticollis, B) Ch. fossulatus; C) Ch. darwini; D) Ch. acuticollis, ventrites 4 & 5; E) Ch. fossulatus, ventrites 4 & 5; F) Ch. acuticollis, ventrite 4, close-up; G) Ch. fossulatus, ventrite 4, closeup. Scale bar = 0.50 mm (A, B, C).

FIGURE 4. Chilarboreus acuticollis, female genitalia: A) dorsal view; B) semi-lateral view; C) bursal sclerite. Scale bar = 0.50 mm (A, B), 0.10 mm (C).

FIGURE2. Chilarboreus acuticollis, female:A) dorsal view; B) pronotum; C) basal portion of pronotum, close-up; D) ventral view; E) head, ventral view, close-up.