Globorentonium, Lawrence, John F. & Slipinski, Adam, 2013

Lawrence, John F. & Slipinski, Adam, 2013, Globorentonium, a new genus of rentoniine Trogossitidae (Coleoptera: Cleroidea) from Australia and Brazil, Zootaxa 3710 (3), pp. 257-270 : 258-259

Globorentonium gen. n.

Type species: G. globulum sp. n.

Diagnosis. The genus may be distinguished from other rentoniines by characters given in the generic key below.

Description. Total length 0.95–1.15 mm. Body short and broad (BL/EW = 1.03–1.28). Upper surfaces strongly convex, smooth and shiny, red to black in color and clothed with fine, decumbent to suberect hairs ( Figs 1 A–F).

Head (excluding labrum) slightly longer than width behind eyes, more or less flattened and strongly declined, with sharp, strongly curved transverse occipital ridge joining posterior edges of eyes ( Figs 4 A, 5A), which are 0.25–0.33 times as long as head, slightly longer than wide and coarsely facetted; antennal insertions barely exposed from above and moderately widely separated; subantennal grooves large, extending behind eyes ( Figs 2 B, 3D, 4B); frontoclypeal suture weakly impressed and straight or absent; clypeus extending well in front of antennal insertions, its anterior edge truncate; labrum strongly transverse. lightly sclerotized, its apex weakly trilobed. Antennae ( Figs 3 B, 4C, 5C) about as long as or slightly longer than head width, 10-segmented with a 1-segmented club longer than preceding five antennomeres combined; scape about 1.8 times as long as wide, widest at base and narrowing apically, with obliquely attached peduncle; pedicel 0.67–0.75 times as long as scape and 1.5–2 times as long as wide; antennomere 3 0.5–0.67 times as long as pedicel and less than 1.5 times as long as wide; remaining funicular segments gradually shorter and broader, becoming strongly transverse just preceding club. wth 9 or 8 and 9 only slightly narrower than club, so that club may appear 2- or 3-segmented; terminal antennomere 1.33–1.67 times as long as wide, narrowly to broadly rounded at apex, and vaguely subdivided. Mandibles slightly longer than wide, narrowly bidentate, with serrate incisor edge; mola well-developed, transversely ridged; prostheca large, membranous, densely pubescent near apex. Maxilla with galea and lacinia apically setose, the latter elongate, about half as wide as former, without uncus; apical palpomere elongate and subconical. Mentum slightly transverse and apically concave; apical labial palpomere similar to that on maxilla but usually shorter and broader. Gulamentum relatively long, about 0.7 times as long as dorsal head length, with a series of transverse striations and divided at about middle by weakly, posteriorly curved transverse groove ( Figs 2 B, 3D, 4B), which is connected laterally to a pair of postocular grooves and the posterior edges of the subantennal grooves; sometimes with short, crescentic, mesal impression ( Fig. 2 B) lying just in front of transverse groove; gular sutures very short and widely separated. Corpotentorium with anterior, acute process ( Fig. 3 D); laminatentoria weakly developed, not meeting at midline. Cervical sclerites well-developed ( Fig. 2 B).

Pronotum 0.31–0.53 times as long as wide, widest at anterior third; sides very weakly curved and strongly converging anteriorly; lateral carinae complete but without margin or bead; anterior edge moderately emarginate; anterior angles rounded; posterior angles right or obtuse; posterior edge strongly, evenly curved, simple and unmargined; disc strongly, evenly convex. Prosternum in front of coxae very short ( Fig. 4 H), about 0.25 times as long as mid length of coxal cavity, broadly emarginate anteriorly; prosternal process incomplete and apically rounded or acute; procoxae strongly transverse and somewhat projecting, with reduced trochantin and well developed coxal plates ( Fig. 3 C) concealing most of femora; procoxal cavities strongly transverse, externally broadly open (without postcoxal projections) and internally closed. Scutellar shield minute, elongate and sharply acute posteriorly, usually concealed by elytral bases and posterior edge of pronotum. Elytra about 0.6–0.92 times as long as wide and 1.43–3.2 times as long as pronotum; sides somewhat sinuate and apices broadly conjointly rounded; disc strongly convex with fine, more or less even punctation; epipleura relatively narrow, except at base, strongly oblique and incomplete. Mesoventrite ( Fig. 4 F, 5F) strongly transverse, separated by sutures from mesanepisterna which are widely separated from one another; anterior edge on a different plane than metaventrite, with pair of large procoxal rests continuing onto mesanepisterna and separated by an anteriorly acute elevated process fitting in between procoxae; mesoventrite expanded posteriorly, with subtruncate apex concealing concavity for receiving metaventral process. Mesocoxal cavities externally separated by mesoventral process, 0.6– 0.8 times as wide as shortest diameter of mesocoxal cavity, but internally subcontiguous, laterally open (partly closed by mesanepisterna and small portion of mesepimeron). Metaventrite ( Figs 4 F, 5F) strongly transverse, its shortest length 0.85–1.5 times as great as shortest diameter of mesocoxal cavity, with pair of straight postcoxal lines extending from lateral third or fouth of mesocoxal cavity to posterolateral corner of ventrite, forming part of crural impression; discrimen and transverse metakatepisternal suture absent; anterior process broadly rounded, overlapping mesoventral process; exposed portion of metanepisternum about 7 times as long as wide, more or less parallel-sided and mesally concave forming part of crural impression; metepimeron concealed. Metacoxae strongly transverse, not extending laterally to elytra, narrowly separated, without coxal plates. Metendosternite with moderately long stalk, long anterior arms, long, slender laminae and anterior tendons located near the apices of anterior arms. Hind wings absent. Legs relatively short and stout; all trochanterofemoral joints strongly oblique, so that femur is in contact with coxa; all femora and tibiae all slightly impressed to receive tibiae and tarsi, respectively; protibia ( Figs 2 D, 3C, 4E, 5B) expanded externally towards apex, widest at apical third or fourth, with outer edge broadly rounded or more or less angulate and sometimes armed with close-set, short spines; mesotibia slightly expanded just beyond base but mostly parallel-sided with contiguous setae only at apex; metatibiae gradually expanded apically, with contiguous spines only at apex; tibial spurs not obvious. Tarsi 5-5-5 with tarsomeres 1–4 more or less equal in length, without ventral lobes ( Figs 3 C, 5B), but sometimes with several long setae beneath; claws simple; empodium well-developed.

Abdomen about 0.6 times as long as wide, with 5 free ventrites ( Figs 3 A, 4G) or with ventrites 1–4 (sternites III–VI) fused together with divisions between them incomplete or absent ( Figs 2 A, 5D); when divisions visible, shortest length of ventrite 1 greater than those of 2 and 3 or 2–4 combined, broadly bi-impressed and with long, slender intercoxal process, narrowly rounded or acute at apex; base of abdomen always more or less tumid along midline, so that ventrites 1–4 each have a short, rounded, posteriorly-projecting process overlapping ventrite behind it or the combined basal ventrites form a single longitudinal ridge; ventrite 5 strongly transverse and broadly rounded at apex. Most abdominal tergites membranous; tergite VIII well sclerotised; spiracles on segments I–VII at edges of tergites. Sternite VIII in male with short or long and slender spiculum relictum. Segment IX with spiculum gastrale which may be moderately long and slender or broad at base and narrowly rounded at apex. Aedeagus ( Figs. 6 A–C, E–H) of cucujiform type, 4.5–7 times as long as wide, with short to moderately long, apically truncate or acute anterior tegminal strut, usually lined with longitudinal baculi; parameres short and broad or moderately long and apically expanded and separate but fused to phallobase; penis about 7 times as long as wide and apically acute or short and membranous, without basal struts. Sternite VIII in female with moderately long, fixed spiculum ventrale; ovipositor ( Fig. 6 D) 1.1–2 times as long as wide; proctiger membranous; paraprocts lightly sclerotized, except for baculil, subequal in length to gonocoxites, each of which is moderately sclerotized and not obviously divided, with slender transverse basal baculum and short, palpiform apical gonostylus.

Figures

FIGURE 1. Globorentonium species, habitus: (A) G. plaumanni sp. n., dorsal, length = 1.05 mm; (B) G. lescheni sp. n., dorsal, length = 1.1 mm; (C – F) G. globulum sp. n., habitus, length = 1.1 mm: (C – D) dorsal; (E – F) lateral.

FIGURE 2. Globorentonium globulum sp. n.: (A) abdomen, ventral; (B) head, ventral; (C) elytron; (D) fore leg.

FIGURE 3. Globorentonium lescheni sp. n.: (A) abdomen, ventral; (B) antenna; (C) fore leg; (D) head, ventral.

FIGURE 4. Globorentonium lescheni sp. n., scanning electron micrographs: (A) head, dorsal; (B) head, ventral; (C) antenna; (D) hind leg; (E) apex of fore leg; (F) pterothorax, ventral, with left mesocoxa and right metacoxa removed; (G) abdomen, ventral; (H) prothorax, ventral, with both coxae removed.

FIGURE 6. Globorentonium genitalia: (A – D) G. globulum sp. n.: (A) tegmen, ventral; (B) penis, ventral; (C) penis, lateral; (D) ovipositor, ventral. (E – F) G. lescheni sp. n.: (E) tegmen, ventral; (F) penis, ventrolateral. (G – H) G. plaumanni sp. n.: (G) tegmen, ventral; (H) tegminal apex, showing small, fixed parameres.