Chilarboreus (Pictarboreus) darwini Ruta, 2011

Ruta, Rafał & Yoshitomi, Hiroyuki, 2018, Description of females of Chilarboreus Ruta, 2011 (Coleoptera: Scirtidae: Scirtinae), Zootaxa 4388 (2), pp. 265-274 : 271

Chilarboreus (Pictarboreus) darwini Ruta, 2011

( Figs 1C , 3C , 7 , 8 )

Material examined. 2 females (EUM): “ CHILI, Prov. Chiloe, \ Isla Chiloe, Chepu \ 14.I.2002 \ T. Cekalovic leg.” Description. Female. Body elongate, widest in the anterior half of elytra, flattened, clothed with two types of setae: procumbent ones and sparse, longer, curved, erect ones ( Figs 1C , 7A ). Coloration brown, without contrasting dorsal pattern. Head as long as wide, 1.4× wider than interocular space, convex, without depression in posterior portion, covered with granulate punctures; eyes small, subtly protuberant. Supraantennal ridge arcuate, forming right angle with anterior margin of clypeus ( Fig. 7E ); clypeus subrectangular. Antennae moderately long, extending to basal 1/4 of elytra; antennomere 1 globular, antennomere 2 cylindrical, narrower and as long as antennomere 1, antennomere 3 long, ca. 1.3× longer than antennomere 2, antennomeres 4–10 gradually shortening, apical antennomere wide, suboval, as long as antennomere 3. Pronotum ( Fig. 7B ) transversely trapezoidal, sides sinuate, widest at anterior portion, lateral carinae subtly crenulate, anterolateral angles produced anteriorly, posterolateral angles right-angled; disc moderately convex, with shallow concavity and deep impunctate groove along basal margin ending in deep pits. Anterior portion of pronotal concavity with two oval excitators covered with numerous minute punctures visible at high magnification ( Fig. 7C ). Punctation of pronotum not granulate, relatively dense on disc (punctures separated by ca. 0.3 diameter) and coarse on sides (punctures touching each other). Elytral punctation irregular, dense in anterior portion (punctures large, separated by ca. 0.5 diameter) and gradually becoming sparse in posterior portion (punctures small, separated by ca. 1.0–2.0 diameters). Elytra subparallel in anterior half, each elytron with subtly marked adsutural stria, longitudinal carinae subtly marked, humeral portion rounded. Hind wings absent. Mesoventral process bilobed at apex. Whole metaventrite covered with punctures, with shallow transverse groove along posterior margin ( Fig. 7D ). Abdomen without paired setal tufts ( Fig. 3C ). Sternite VIII elongate (L 0.57 mm), with a pair of subparallel apodemes fused basally; tergite VIII long (L 0.88 mm), apical portion subtrapezoidal; ovipositor long (L 1.24 mm), branchlets absent, coxites membranous, triangularly elongate, not covered with setae, styli missing in the studied specimen ( Fig. 8A, B ). Bursal sclerite ( Fig. 8C, D ) small (L 0.38 mm, W 0.19 mm), subcylindrical, with complex armature of setae and spines.

Measurements and ratios. N=2: TL 2.01–2.30 (2.16), PL 0.47–0.50 (0.49), PW 0.68–0.70 (0.69), EL 1.55– 1.80 (1.68), EW 0.90–1.00 (0.95), TL/EW 2.2–2.3 (2.3), PW/PL 1.4–1.5 (1.5), EL/EW 1.7–1.8 (1.8), EL/PL 3.3– 3.6 (3.5).

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

FIGURES8. Chilarboreus darwini, female genitalia:A) dorsal view; B) lateral view; C) bursal sclerite, lateral view; D) bursal sclerite, dorsal view.Scale bar = 0.50 mm (A, B), 0.10 mm (C, D).