Chilarboreus, Ruta, 2011

Ruta, Rafał, 2011, Chilarboreus gen. nov., a new genus of Chilean Scirtidae (Coleoptera: Scirtoidea), with descriptions of three new species, Journal of Natural History 45 (27 - 28), pp. 1689-1713 : 1692-1696

Subgenus Chilarboreus subgen. nov.

( Figures 1A,B ; 2 A–D, J; 3–8)

Type species. Chilarboreus fossulatus sp. nov.

Diagnosis

Pronotum bears distinct, deep fossae in anterolateral portion; punctation of basal and lateral portions of pronotum granulate; lateral edges of pronotum straight; aedeagus flattened, moderately to strongly elongated; dorsum uniformly brown.

Description

Male. Body elongated, TL 2.1–2.4 mm, TL / EW 2.0–2.3, moderately convex. Body brown, covered with yellowish, procumbent setae, head and pronotum with granulate punctures in basal and lateral portions, remaining portions of dorsum covered with normal (not granulate) punctures, not microreticulated.

Head as long as broad, base concealed from above by pronotum; eyes small, oval, slightly protuberant, relatively coarsely faceted; tempora well marked, distance from posterior margin of eye to occipital ridge equal to the diameter of the eye, slightly converging basally; distance from ventral margin of eye to subgenal ridge equal to the diameter of the eye; supraantennal ridges slightly elevated, oblique, joined mesally to clypeal margin; frons distinctly convex; paired antennal fossae lying below carinae shallow, extending laterally to carina, parallel to edge of eye and ventrally reaching transverse ridge connecting edge of eye with clypeal margin; eyes surrounded by trough-shaped groove; antennal insertions moderately large and partly visible from above. Frontoclypeal suture absent; clypeus very short, transverse, c.5.0 times wider than long, with transversely rectangular emargination, lateral margins converging anteriorly. Anteclypeus present in emargination of clypeus. Ventral portion of head between subgenal ridges concave, gular area slightly convex, transversely rectangular, 1.3 times wider than long; submentum short, slightly longer than wide, much longer than mentum, sides diverging anteriorly. Subgenal ridge well marked, without indentation in anterior portion. Antennae moniliform; antennomeres subtly widened apically, covered with long hairs; antennomere 1 widest, globular, without ridge on anterior margin; antennomere 2 cylindrical, slightly narrower and c.1.2 times longer than antennomere 1; antennomere 3 longest, c.1.5 times longer than antennomere 2; antennomeres 4–10 of similar length, as long as antennomere 2; apical antennomere wide, as long as antennomere 3. Antennae distinctly microreticulated. Labrum clearly visible, transverse, c.3.0 times wider than long, anterior margin slightly emarginated, anterolateral angles broadly rounded, slightly membranous. Mandibles symmetrical, c.2.2 times longer than width at bases, abruptly curved in apical third, apices unidentate, basal two-thirds of outer margin covered with setae; inner margin of mandibles with a minute triangular denticle, small indentation present behind denticle; molar region not developed. Basistipes with very scarce setation. Maxillary palpi: palpomere 1 narrow, 2 wider, as long as 1, 3 somewhat shorter than 2, subtriangular, 4 spindleshaped, 1.5 times longer than 3, without setae. Galea short and broad, not widening apically, with long, fringed, irregularly arranged setae at apex; lacinia with straight, subtle setae and distinct apical hook; row consisting of few setae parallel to inner margin present. Mentum transverse (W / L = 2.0), trapezoidal, with slightly rounded, but well-marked anterior angles. Ligula narrow at base, widening apically, apical portion bilobed, covered with long, dense setae. Labial palpomeres: palpomere 1 long, narrow, c.3.0 times wider than long; palpomere 2 arcuate, as long as palpomere 1; apical palpomere arising from the apex of preapical one, cylindrical, sinuous, c.1.3 times longer than palpomere 1, without setation. Cervical sclerites large, triangular.

Pronotum moderately transverse, narrower than bases of elytra, 1.3–1.5 times wider than long; sides subparallel or slightly widening basally, lateral margins slightly depressed; disc convex, with distinct fossulate depressions in anterolateral portions; anterior margin rounded; anterolateral angles acute, right-angled, not or slightly projecting; posterior angles right-angled, well marked; base bisinuate, with distinct groove parallel to basal margin, ended with deep fossae. Prosternum highly reduced anteriorly; prosternal process wide, rhomboidal, c. 2.0 times longer than wide, covered with delicate setae, with longitudinal keel on ventral surface.

Scutellum small, oval to pentagonal, slightly longer than its width, flat, with rounded or pointed apex; anterior margin straight. Elytra elongated, distinctly wider at base than pronotal base; humeri well marked, apices regularly rounded, elytra with longitudinal depression parallel to the suture, distinctly narrowed in anterior portion behind humeri, two longitudinal carinae and adsutural stria subtly marked. Epipleura wide at base, wider than metanepisternum, regularly narrowing till apex, slightly translocated on lateral portion of elytra and appearing very narrow in ventral view, present till apex. Punctation of elytra irregular, not granulate, uniform, rather sparse, punctures separated by c.2.0 diameters. Internal elytral process not marked.

Hind wings c.2.2 times longer than its width; radial cell oval; venation reduced; apical portion of r3 marked, straight; r4 present as a slightly visible darkened area; rp-mp2 arcuate, forming right angle with MP 1+2; CuA+AA 1+2 absent. Medial field with two free veins; pigmented areas: radial cell, three areas in apical field.

Mesoventrite small; anterior margin with distinct coxal rests; longitudinal suture not marked on mesoventral process; anterior portion forming widely triangular fossa for the reception of the prosternal process; mesoventral process short, as long as wide, sides subparallel or slightly converging posteriorly, apex truncate, touching metaventrite; mesocoxae completely separated by a process; mesanepisternum rhomboidal, as long as wide, forming coxal rest for procoxa; mesepimeron smaller, distinctly punctured, triangular, strongly narrowed mesally; mesocoxal cavities closed laterally by narrow processes of mesepimeron and mesanepisternum; mesocoxae triangular, slightly projecting; mesotrochantin hidden, rectangularly elongated.

Metaventrite moderately long, transverse (W / L 2.6), convex; discrimen present on posterior three-quarters of its length; impunctate and smooth in posterior portion; distinct transverse groove present along posterior margin of metaventrite; metanepisternum trapezoidal, long, c.3.0 times longer than its width, slightly narrowing posteriorly; anterior portion of metaventrite forming elevated, transverse ridge. Metacoxae moderately large, strongly oblique, 3.0 times wider than its length, extending laterally to epipleura; metacoxal plate obliquely narrowing, present on almost whole length of metacoxa, reduced in outermost portion. Metendosternite short, lateral furcal arms long, relatively narrow in basal portion; ventral processes well marked, triangular; anterior furcal arms narrow, elongated.

Legs long; femora extending beyond elytral margin, trochanter moderately long; trochantero-femoral joint oblique; femora not touching coxae, as long as tibiae, widened in the middle of their length. Subfemoral grooves with distinct, hexagonal microreticulation. Tibiae narrow, slightly widened at apex, with paired carinae; metatibial spurs short, shorter than metatibial width; tarsi longer than half length of tibiae; tarsomere 1 elongated, narrow, slightly triangularly widened, as long as tarsomeres 2 and 3 combined; tarsomere 4 bilobed apically; apical tarsomere as long as tarsomeres 3 and 4 combined.

Abdomen c.1.4 times longer than its width, convex; ventrites 1–2 fused; ventrites 1–4 of subequal length; ventrite 5 slightly longer; anterior margin of ventrite 1 slightly elevated; ventrite 5 regularly rounded at apex. Abdominal ventrites regularly covered with setae. Laterosternites narrow, reduced in two-thirds of length of apical ventrite. Tergites 1–7 slightly sclerotized, covered with setae arranged in a peculiar hexagonal pattern, areas devoid of setae weakly visible, marked as shallow areas in basal portions of tergites; apodemes of tergite 7 reduced in males, only slightly exceeding length of the tergite; spiracles localized on ventral sides of pleura.

Sternite 9 oval, membranous, with dense setae on apical margin, slightly wider than its length, apodemes fused at bases. Tergite 8 with short apodemes and elongated, regularly rounded apical portion, covered with stout, short setae, longer setae present on apical margin; apodemes distinctly shorter than apical portion. Tergite 9 with short apodemes, apical portion devoid of setae; sparse setae present only on apical margin. Aedeagus symmetrical, dorsoventrally flattened. Tegmen small, reduced to a bilobed, flat structure. Penis distinctly longer than its width, with oval pala, which is as long as trigonium; parameroids narrow, mesal process truncate or deeply excised.

Female (based on C. fossulatus ). TL 2.1. Eyes small; tempora very long, distinctly longer than diamter of an eye; distance between lower margin of eye and subgenal ridge larger than diameter of an eye; basal portion of pronotum parallel to basal groove smooth, impunctate. Wings reduced; humeri not marked; sides of elytra rounded; elytral apices flattened; mesoventral fossa very wide; metaventrite short (W / L 3.2); punctation of abdomen subtle; ventrite 5 with two tufts of setae; apodemes of tergite 7 short, but better developed than in male.

Sternite 8 elongate rectangular, with a pair of subparallel apodemes fused basally, with sparse setae at apex. Tergite 8 very long; apical portion trapezoidal, slightly longer than its width, with sparse setation on apical margin; apodemes long, c. 3.5 times longer than apical portion. Ovipositor long, slightly shorter than abdomen, c.7.5 times longer than its width; branchlets absent; coxites membranous, triangularly elongate, not covered with setae; styli with two tufts of setae at apex. Prehensor small, triangular, with numerous spinose outgrowths.

Figures

Figure 1. Habitus. (A) Chilarboreus (Chilarboreus) fossulatus; (B) Chilarboreus (Chilarboreus) acuticollis; (C) Chilarboreus (Pictarboreus) darwini. Scale bar 1.0 mm.

Figure 2. Morphological details. (A–D, J) Chilarboreus (Chilarboreus) fossulatus; (E–I, K) Chilarboreus (Pictarboreus) darwini; (A, E) mandible; (B, F) maxilla; (C, G) labium; (D, H) labrum; (I) elytron; (J, K) wing. Abbreviations: lh, laciniar hook (uncus). Scale bars 0.1 mm (A–H), 0.6 mm (I), 0.7 mm (J, K).