Cyrtonion moto, Fikáček, 2008

Fikáček, Martin, 2008, A new species of the genus Cyrtonion (Coleoptera: Hydrophilidae: Megasternini) from the Democratic Republic of the Congo, Acta Entomologica Musei Nationalis Pragae (suppl.) 48 (1), pp. 27-35 : 29-31

Cyrtonion moto sp. nov.

( Figs. 1-2 , 6 )

Type locality. Democratic Republic of the Congo, Ituri prov., Moto, 3°10′N 29°30′E, 790 m a.s.l.

Type material. HOLOTYPE: ♁, ‘MUSÉE DU CONGO / Haut Uelé [= upper Uelé riv.]: Moto / 1920 / L. Burgeon // Pachysternum / sculpticolle Rég. / J. Balfour-Browne det. 1953’ ( MRAC). PARATYPE: 1♀, ‘MUSÉE DU CONGO / Haut Uelé [= upper Uelé riv.]: Moto / -X-XI-1920 / L. Burgeon’ ( MRAC).

Description. Body broadly oval, maximum width in anterior 0.3 of elytra; elytra highly convex in lateral view; pronotum more convex than elytra, not forming continuous curve with them in lateral view. Length of holotype: 2.7 mm; width of holotype: 1.7 mm.

Coloration. Dorsal and ventral body surface dark reddish brown, elytra slightly paler than pronotum. Ventral side of head, lateral portions of prosternum, legs, antennae and mouthparts reddish.

Head. Clypeus with dense, moderately coarse setiferous punctation, interstices without microsculpture; anterior margin narrowly rimmed, angulate with straight median part in male, only indistinctly angulate in female. Frons divided from clypeus by complete transverse ridge connecting antennal bases. Surface with dense coarse setiferous punctation, interstices narrow, without microsculpture. Eyes rather small, interocular distance 6× larger than width of one eye. Mentum with anterior margin indistinctly concave medially, with rather deep narrow cleft sublaterally; surface with dense and coarse punctation posterolaterally and sculpture consisting of transverse ridges in median portion. Antenna with 9 antennomeres, scapus ca. as long as antennomeres 2-5 combined; antennal club elongate, antennomere 9 blunt at apex. Maxillary palpomeres 2-4 subequal in length, palpomere 2 widened apically.

Prothorax. Pronotum with deflexed lateral portions (those portions seen in ventral view); dorsal portion slightly explanate laterally, with two high submedian bulges divided by narrow ridge, false lateral margins bisinuate laterally. Dorsal surface with rather dense, coarse setiferous punctation, interstices without microsculpture; punctures becoming smaller and sparser on pronotal bulges. Posterior part of pronotum without defined transverse row of coarser punctures. Prosternum with large antennal grooves reaching deflexed parts of pronotum; median portion of prosternum plate-like with deep posterior median cleft; plate distinctly divided from lateral parts, finely carinate medially, bearing sparse punctures and rugose microsculpture.

Mesothorax. Preepisternal elevation in form of subpentagonal plate widely contacting anteromedian portion of metaventrite; surface with rather sparse, moderately coarse punctation, interstices without microsculpture. Cavities for reception of procoxae deep, reaching preepisternal elevation. Elytra with 10 punctate striae; lateral parts of elytra deflexed. Interval punctation of elytra very fine and sparse consisting of setiferous scar-like punctures; punctural series consisting of rather coarse, shallow, sparsely distributed punctures. Intervals highly convex, bearing higher and wider bulges on following positions: interval 2 (between series 1 and 2) – short bulge on anterior 0.4, long bulge in whole posterior 0.5; interval 3 – short bulge on elytral base; interval 4 – short high bulge at midlength, short smaller bulge subapically; interval 5 – short bulge in anterior 0.4; interval 6 – short bulge subapically; interval 7 – short bulge at elytral base and in posterior 0.6; interval 9 – short low bulge at elytral base; intervals 8 and 10 lacking bulges. Epipleuron narrow in anterior 0.4, becoming very narrow posteriorly of metathorax, then narrowing towards elytral apex.

Metathorax. Median part of metaventrite without defined pentagonal median area, divided from lateral portions by very distinct and complete femoral lines going arcuately from metacoxal attachements to anterolateral corners of metaventrite; median portion (mesally of femoral lines) with coarse but rather sparse punctation, interstices without microsculpture; lateral portions (laterally of femoral lines) with much denser punctation consisting of punctures similar to those on median portion, interstices dull, but without distinct microsculpture. Anterolateral ridge absent, anterolateral part of median portion of metaventrite neither divided by ridge nor concave. Hind wings completely developed.

Legs short, tibiae ca. as long as femora and coxae combined; anterior tibiae slightly flattened, widened at apex, with outer margin in shape of continuous curve.

Abdomen. Ventrite 1 carinate medially, bearing coarse puntation; ventrites 2-5 ecarinate, with punctation consisting of smaller punctures than on ventrite 1. Interstices of ventrites 1-5 without microsculpture.

Male genitalia ( Figs. 1-2 ). Parameres ca. as long as phallobase, gradually narrowing from base to blunt, membranous apex. Phallobase wide, 1.6× longer than wide, lateral parts partly reduced, posteriorly bearing long slightly asymmetrical manubrium. Median lobe wide and long, widest basally, ca. 4× longer than wide, continuously narrowing from base to apex; apex blunty rounded; corona situated in apical 0.15.

Variation. The shape of anterior margin of clypeus is angulate in male holotype, but only indistinctly angulate in female paratype. In the paratype, elytral intervals including bulges are slightly lower than in the holotype. No other variation was observed.

Differential diagnosis. The species is externally very similar to both remaining Cyrtonion species, but can be easily distinguished by the wider aedeagus with rounded apex of the median lobe (in contrast, median lobe is pointed apically in C. ghanense and C. sculpticolle ).

Etymology. The species name refers to the village name, where both type specimens were collected. It stands as a noun in apposition.

Bionomics. No habitat information is available.

Distribution. Democratic Republic of the Congo; the species is known only from the type locality (see Fig. 6 ).

Figures

Figs. 1-4. Aedeagophores of Cyrtonion Hansen, 1989 species. 1-2 – C. moto sp. nov., holotype; 3 – C. ghanense Hansen, 1989, paratype; 4 – C. sculpticolle (Régimbart, 1907), paratype. 1 – aedeagus; 2-4 – apical portion of the median lobe.

Fig. 6. Known distribution of the species of the genus Cyrtonion Hansen, 1989. Green area covers distribution of evergreen rain forest.