Orthogonius emarginatus, 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 : 262-263

Orthogonius emarginatus , new species

( Figs. 1–6 )

Type material. – Holotype: male, labeled “Coll. I. R. Sc. N. B. / Singapore, Nee Soon, Mal trap 1, Swamp forest , Station 25046. 5 Apr. 2005. P. Grootaert coll.”, collected at Nee Soon, Singapore (type locality) and deposited in IRSNB.

Description. – Body: Length 15.0 mm; width 6.0 mm. Form stout; surface markedly shiny.

Color: Body black; antennae, palpi, legs and ventral surface reddish dark brown.

Macrosculpture. Head: dorsal surface without striation, but densely and moderately punctate; base of neck and median portion of vertex impunctate. Pronotum smooth, glabrous, shallowly striate. Elytra with intervals very shallowly and sparsely punctate. Ventral surface smooth and glabrous.

Microsculpture: Mesh pattern isodiametric on dorsal surface of head, but densely and moderately transverse on pronotum and elytra.

Head: Slightly wider than long (HW/HL = 1.15), convex. Frontal impressions large and deep, fovea-like, not extended to level of anterior pair of supraorbital setae; clypeus bisetose, surface uneven, slightly raised at base. Eyes very large and markedly prominent, longitudinal diameter of eye about twothirds distance between eyes. Antennae rather long, slightly extended over base of elytra; antennomere 4 longer than antennomere 3, almost twice as long as antennomere 2.

Mouthparts: Labrum six setose, straight at front margin.

Maxillae: palpal articles subcylindrical, glabrous.

Labium: submentum with a pair of setae; mentum without median tooth, with a pair of setae; glossal sclerite short, quite stout, bisetose at apex; palpal articles subcylindrical, glabrous; palpiger asetose; palpomere 2 bisetose on inner margin.

Prothorax: Pronotum — form transverse (PW/PL=1.66), widest at about middle; both fore and basal margins finely beaded; sides anteriorly and posteriorly evenly contracted; the lateral expanded margins comparatively narrow, quite even throughout, smooth and evidently reflexed; both fore and hind angles round; disc markedly convex; anterior and posterior transverse impressions distinct, deep and wide; posteriolateral foveae small. Prosternum — intercoxal process unbordered at apex.

Elytra: Form elongate (EL/EW=1.5), parallel at sides in middle portion; surface rather flat; basal border indistinct basad intervals 1–5; humeri square; apex roundly truncate, sutural angle nearly rectangular ( Fig. 3 ); striae fine and deep, intervals slightly convex, except interval 7 carinate in basal half; intervals subequal in width in middle portion; interval 3 with only basal setiferous puncture.

Legs: Middle coxae glabrous. Femora — hind femur comparatively slender, with only one seta on posterior margin of ventral surface, at one-fourth from base. Tibiae — fore tibia slightly dilated at apex, latter rounded and sinuate near outer apical angle ( Fig. 1 ); middle tibia robust, markedly dilated at apical portion, outer apical surface slightly but evidently emarginate in outer apical portion ( Fig. 2 ); apical spurs of hind tibia long and sharp. Tarsi — hind tarsomere 3 much longer than tarsomere 4; tarsomere symmetrically bilobed at apex; all tarsal claws pectinate, pectens very short.

Abdomen:Abdominal ventrite VII of male deeply emarginate at apical margin ( Fig. 4 ).

Male genitalia: Median lobe of aedeagus robust ( Figs. 5–6 ), ventral margin markedly sinuate, evenly constricted toward apex, obtuse and somewhat tube-like; dorsal orifice long; apical lamella slightly narrowed toward apex, slightly longer than wide.

Female: Unknown.

Etymology. – The specific epithet, “emarginatus”, is a Latin adjective, nominative case, referring to the emargination of middle tibia in outer apical portion, which characterises this species.

Comparisons. – This new species is closely resembles to O. andrewesianus Tian & Deuve (2006d) , but it is easily distinguishable from the latter by its larger size, labrum that is straight at the front margin (slightly convex in O. andrewesianus ), base of elytra indistinctly bordered (unbordered against intervals 1–3 in O. andrewesianus ) and the stouter aedeagus.

Distribution. – This species is known only from Singapore.

Figures

Figs. 1–6. Line drawings of structural features of Orthogonius emarginatus, new species: 1, left fore tibia, dorsal view; 2, left mid femur, ventral view; 3, apex of right elytron; 4, abdominal ventrite VII of male, ventral view; 5, aedeagus, right lateral view; 6. apical portion of aedeagus, dorsal view. Scale bars: 1 mm. A for Figs. 3–4; B for Figs. 1–2 and 5–6.