Orthogonius cyclothorax, Tian & Deuve, 2007

Tian, Ming-yi & Deuve, Thierry, 2007, A Taxonomic Treatment Of The Species Of Orthogonius Macleay (Coleoptera: Carabidae: Orthogoniini) Of Singapore, Raffles Bulletin of Zoology 55 (2), pp. 261-266 : 263-264

Orthogonius cyclothorax , new species

( Figs. 7–11 )

Type material. – Holotype: male, labeled “Coll. I. R. Sc. N. B. / Singapore, Nee Soon, Mal trap 2, Swamp forest , Station 25068. 19 Apr. 2005. P. Grootaert coll.”, collected at Nee Soon, Singapore (type locality) and deposited in IRSNB.

Description. Body: Length 10.5 mm; width 4.5 mm. Form stout, moderately shiny.

Color: Head dark brown, pronotum and elytra reddish brown; legs (except femora), ventral surface, palpi of mouthparts, antennae and labrum brown; femora yellow.

Macrosculpture: Head and pronotum shallowly striate, impunctate, intervals 3, 5, 6 and 8 of elytra with sparse, small punctures.

Microsculpture: Mesh pattern isodiametric on head, pronotum and elytra; microlines dense.

Head: Slightly narrower than long (HW/HL = 0.92), stout, evidently convex. Frontal impressions pit-like, small; clypeus bisetose, surface quite even. Eyes very large, prominent. Antennae rather long, extending to about one-fifths of elytra from base; pubescent from apical two-thirds of antennomere 4; antennomere 4 as long as antennomere 3, but less than two times of antennomere 2.

Mouthparts: Labrum six setose, anterior margin distinctly emarginate. Maxillae: palpi subcylindrical, palpomeres 3 and 4 subequal; palpomere 3 with several short setae at apex. Labium: submentum with one seta on either side; mentum without median tooth, asetose; glossal sclerite of ligula small, bisetose at apex; palpomeres with articles subcylindrical, palpomere 2 slightly longer than palpomere 3; palpomere 2 bisetose on inner margin with a few short setae at apex.

Prothorax: Pronotum — form transverse (PW/PL = 1.82), widest at slightly posteriad middle; both anterior and posterior margins beaded; fore and hind angles round; sides evenly broadened; lateral expanded margins clearly defined, smooth and hardly reflexed; disc convex; anterior and posterior transverse impressions shallow, posteriolateral foveae small. Prosternum — intercoxal process distinctly bordered at apex.

Elytra: Form broadly ovate (EL/EW = 1.44), parallel at sides at middle portion, surface moderately convex; basal border complete; humeri square, apex broadly truncate, sutural angle nearly rectangular ( Fig. 8 ); striae rather deep, intervals quite flat, subequal in width at middle portion; interval 7 flat, not carinate; interval 3 with middle and hind setiferous punctures, basal puncture absent.

Legs: Middle coxae glabrous. Femora — hind femur moderate, with two setae on posterior margin of ventral surface. Tibiae — fore tibia stout, gradually enlarged at apex, apical margin sinuate, outer angle rectangular ( Fig. 7 ); middle tibia slender; hind tibia hardly dilated at apex, apical spurs long and sharp. Tarsi — hind tarsomere 4 shorter than tarsomere 3, shallowly emarginate at apex; all tarsal claws pectinate, pectens long.

Abdomen: Abdominal ventrite VII of male complete, without emargination at apical margin ( Fig. 9 ).

Male genitalia: Median lobe of aedeagus slightly expanded in middle portion, apex abruptly terminated and pointed; apical lamella small, longer than wide, obtuse at apex ( Figs. 10–11 ).

Female: Unknown. Etymology. – The specific epithet is a combination of the Greek adjectival prefix “cyclo-”, meaning round, and feminine noun “thorax”, referring to the form of the pronotum which has rounded fore and hind angles.

Comparisons. – This new species is similar to O. medanensis Tian & Deuve, 2006 of Sumatra, but is markedly distinct in the following morphological features: its mentum is without seta (2 setae in O. medanensis ), interval 3 of elytra is without basal setiferous punctures (evident in O. medanensis ) and apical lamella of aedeagus is narrower (broader in O. medanensis ).

Distribution. – This species is known only from the type locality, Singapore.

Figures

Figs. 7–11. Line drawings of structural features of Orthogonius cyclothorax, new species: 7, left fore tibia, dorsal view; 8, apex of right elytron; 9, abdominal ventrite VII of male; 10, aedeagal median lobe, right lateral view; 11, apical portion of aedeagal median lobe, dorsal view. Scale bars: 1 mm. A for Figs. 8–9; B for Figs. 7, 10–11.