Chilarboreus (Pictarboreus), 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 : 1704-1708

Subgenus Pictarboreus subgen. nov.

( Figures 1C ; 2 E–I, K; 9–11)

Type species. Chilarboreus darwini sp. nov.; by present designation.

Diagnosis

Pronotal surface even, without fossae in anterolateral portions; punctation of basal and lateral portion of pronotum normal, not granulate; lateral edges of pronotum slightly diverging anteriorly, widest in basal portion; aedeagus cylindrical, elongated; dorsum usually with dark, extremely variable pattern on elytra.

Description

Male. Body elongated, TL 2.2–2.5 mm, TL / EW 2.2–2.4, moderately convex. Body brown to blackish-brown, head black, covered with yellowish, procumbent setae, head and pronotum with normal (i. e. 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; distance from ventral margin of eye to subgenal ridge equal to half diameter of the eye; tempora slightly converging basally; 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, its width c.5.0 times its length, truncate, lateral margins subparallel. Anteclypeus developed, slightly shorter than clypeus. Ventral portion of head between subgenal ridges concave; gular area slightly convex, transversely rectangular, its width c.1.3 times length; submentum short, slightly longer than wide, much longer than mentum, sides diverging anteriorly. Subgenal ridges well marked, without indentation in anterior portion. Antennae moniliform; antennomeres subtly widening apically, covered with long hairs, distinctly microreticulated; antennomere 1 widest, globular, without ridge on anterior margin; antennomere 2 cylindrical, slightly narrower than antennomere 1, as long as antennomere 1; antennomere 3 longest and narrowest, c.1.5 times longer than antennomere 2; antennomeres 4–10 gradually shortening till apex, slightly shorter than antennomere 3; apical antennomere wide, as long as antennomere 3. Labrum clearly visible, transverse, its width c.3.0 times length; anterior margin deeply emarginated; anterolateral angles broadly rounded, slightly membranous. Mandibles symmetrical, c.2.2 times longer than wide at bases, abruptly curved in apical third; apices unidentate; basal two-thirds of outer margin covered with setae; inner margin with deep and narrow incision; basal portion of mesal edge with three small denticles; molar region not developed. Basistipes with very scarce setation. Maxillary palpi: palpomere 1 triangular; 2 and 3 rectangular, as long as 1; 4 spindle-shaped, c.1.5 times longer than 3, without setae. Galea short and broad, not widening apically, with extremely elongated, fringed, irregularly arranged setae at apex; lacinia narrow, with straight, subtle setae and distinct apical hook; row of setae parallel to inner margin present, consisting of a few setae. Mentum transverse (W / L = 2.0), trapezoidal, with rounded anterior angles. Ligula narrow at base, widening apically; anterior margin deeply excised; apical portion bilobate, covered with long, dense setae. Labial palpomeres: palpomere 1 long, narrow, c.3.0 times wider than its length; palpomere 2 slightly widened, arcuate, as long as palpomere 1; apical palpomere arising from the apex of preapical one, cylindrical, sinuous, c.1.5 times longer than palpomere 1, without setation. Cervical sclerites large, triangular.

Pronotum moderately transverse, distinctly narrower than base of elytra; sides widening basally, lateral margins sinuate, not depressed; pronotal disc evenly convex, with longitudinal line devoid of punctures; anterior margin rounded; anterolateral angles acute, right-angled, not projecting; posterolateral angles right-angled, well marked; base bisinuate, with narrow groove parallel to basal margin, ended with small fossae. Prosternum highly reduced anteriorly; prosternal process wide, rhomboidal, c.3.0 times longer than its width, covered with delicate setae, with longitudinal keel on ventral surface.

Scutellum small, oval, slightly longer than wide, flat, with rounded apex; anterior margin straight. Elytra elongated, distinctly wider at base than pronotal base, with longitudinal depression parallel to the suture, distinctly narrowed in anterior portion behind humeri; humeri well marked; apices regularly rounded; longitudinal carinae subtly marked, adsutural stria not marked. Epipleura wide at bases, 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, dense, punctures separated by c.1.0 diameter. Internal elytral process not marked.

Hind wings c.2.2 times longer than wide; radial cell oval; venation reduced; apical portion of r3 well marked, straight; r4 not marked; rp-mp2 arcuate, forming with MP 1+2 right angle; CuA+AA 1+2 absent. Medial field with two free veins; pigmented areas: radial cell, small area in apical field.

Mesoventrite small; anterior margin with distinct coxal rests; longitudinal suture not marked on mesoventral process; anterior portion forming hexagonal fossa for reception of prosternal process; mesoventral process slightly longer than wide; sides converging posteriorly; apex emarginated, 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; mesocoxa triangular, slightly projecting; mesotrochantin hidden, rectangularly elongated.

Metaventrite long (W / L 2.2), convex; discrimen present on posterior threequarters of its length, sparsely punctate in posterior portion; distinct groove is 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. Metacoxa moderately large, strongly oblique, c.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 indistinct, irregular, squamiform microreticulation. Tibiae narrow, slightly widening at apex, with paired carinae; metatibial spurs short, shorter than metatibial width; tarsi c.1.5 times 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.1.5 times longer than wide, convex; ventrites 1–2 fused; ventrites 1–4 of subequal length; ventrite 5 slightly longer; anterior margin of ventrite 1 slightly elevated; apical ventrite regularly rounded at apex. Abdominal ventrites regularly covered with setae. Laterosternites narrow, reduced in two-thirds length of apical ventrite. Tergites 1–7 slightly sclerotized, covered with peculiar hexagonal setation, areas devoid of setae weakly visible, marked as shallow areas in basal portions of tergites; apodemes of tergite 7 reduced, only slightly exceeding length of the tergite; spiracles localized on ventral sides of pleura.

Sternite 9 membranous, reduced to two elongated plates. 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 moderately long apodemes, apical portion with only a few marginal setae. Aedeagus symmetrical, cylindrical. Tegmen large, forming theca enclosing penis. Penis with narrow basal portion, widening apically; trigonium truncate, with denticle on ventral side; parameroids wide, elongated, subrectangular.

Female. Unknown.

Etymology

Combination of Latin picturatus (painted) and a generic name Chilarboreus , refers to the dorsal pattern present in majority of specimens; gender masculine.

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).