Oesyperus pygmaeus Andrewes, 1923

Kataev, Boris M., 2006, A taxonomic review of the genus Oesyperus (Coleoptera: Carabidae: Harpalini), Zootaxa 1286, pp. 43-55 : 51-54

Oesyperus pygmaeus Andrewes, 1923

( Figs 3 , 5 , 12–14 )

Oesyperus pygmaeus Andrewes, 1923: 446 . Type locality: "Madras: Palni Hills, Marian Shola, 7200 feet ”, India.

Type material. Paratype: ɗ, labelled "Palni Hills, Marian Shola, ca. 7200 ft., S.W. Kemp, under rotten wood in dense jungle, S. W. K.", " Cotype" [on round piece of paper with green margin], " Oesyperus pygmaeus Andr., Cotype, H.E. Andrewes det.", "Indian Mus. Calcutta", "H.E. Andrewes Coll., B. M. 1945–97 " ( NHML).

Redescription (based on the paratype). Size: Length 6.4 mm, width 2.6 mm.

Habitus: Fig. 3 .

Colour: Dark brown, nearly black, poorly shiny on elytra, head and pronotum somewhat dull; labrum paler, reddish brown. Palpi, antennae and legs brownish yellow.

Head: Large (WHmax/WPmax = 0.78; WHmin/WPmax = 0.68), with small and weakly convex eyes separated from buccal fissure ventrally by distance longer than width of first antennomere and slightly shorter than length of second antennomere. Temples moderately long, flat, sloping to neck constriction. Frontal suture shallow; clypeo­ocular prolongations rather evenly curved, deepened at clypeus, superficial at eyes. Supraorbital furrows ( Fig. 5 ) straight, moderately prolonged to neck constriction behind eyes and not curved ventrad distally. Labrum moderately deeply concave apically. Penultimate labial palpomere approximately equal to apical palpomere. Puncturation of dorsal surface of head rather coarse and irregular, with distance between punctures usually slightly greater than their diameter; on frons puncturation very sparse. Dorsal microsculpture visible throughout, consisting of very distinct isodiametric, almost granulate meshes.

Pronotum: Weakly convex and weakly transverse, 1.38 times as wide as long, widest in anterior third, notably narrowed basad (WPmax/WPmin = 1.38). Apical margin slightly, arcuately emarginate, bordered only at apical angles. Apical angles slightly protruding, acute, blunt at apices. Basal margin somewhat straight, narrower than apical margin and slightly narrower than base of elytra between humeral angles, without distinct basal border (bead hardly distinct at basal angles). Sides very widely rounded up to distinct obtuse basal angles, narrowly bordered throughout. Lateral depressions not developed; basal foveae very small, oval and shallow. Dorsal puncturation irregular, rather coarse and sparse, distributed throughout, with distance between punctures along margins approximately equal to their diameter and in central portion of pronotal disc greater than their diameter. Dorsal microsculpture distinct throughout, consisting of isodiametric, almost granulate meshes.

Elytra: Oval, moderately long, 1.45 times as long as wide, 2.60 times as long and 1.30 times as wide as pronotum, rather strongly convex, without basal depressions. Humeri not prominent, widely rounded at apices. Preapical sinuation moderate. Sutural angle acute, narrowly rounded at apex. Basal bead glabrous, almost straight, forming with lateral margin a very obtuse angle. Striae impunctate, slightly deepened throughout. Parascutellar striole strongly reduced, indistinct; basal pore distinct, isolated from basal bead. Intervals slightly convex, weakly narrowed to apex; eighth and ninth intervals not widened apically. All intervals rather coarsely punctate, with two punctures in transverse row on each interval on disc. Each third interval with 3–4 discal pores usually connected with second stria. Microsculpture visible throughout, consisting of large, more or less isodiametric meshes.

Legs: Protibia with one preapical spine on outer margin; apical spur slightly longer than first protarsomere. Metafemur with two setae along posterior margin. Metatarsus shorter than WHmin, with first tarsomere approximately as long as second and third combined.

Male genitalia: Median lobe of aedeagus ( Figs 12–14 ) arcuate, with arcuate ventral margin of medial portion (lateral aspect). Terminal lamella ( Fig. 13 ) short and wide, slightly bend dorsad apically, with sides roundly converging to rounded apex.

Distribution. Known only from the type locality (Marian Shola) in Palni Hills, southern India. The beetles were collected under rotten wood in dense jungle.

Remarks. Oesyperus pygmaeus is easily recognized by the small body and the rather convex elytra with strongly reduced parascutellar striole and without basal depressions. In addition, the head is relatively wider and the median lobe is more arcuate than in other species.

Figures

FIGURES 1 – 3. Oesyperus, habitus. 1, Oe. unctulus; 2, Oe. planus; 3, Oe. pygmaeus. Scales = 25.0 mm (A: 1, 2; B: 3).

FIGURES 4 – 5. Oesyperus, head, lateral aspect. 4, Oe. planus; 5, Oe. pygmaeus. Scale = 1.0 mm.

FIGURES 9 – 14. Oesyperus, median lobe (10, 13, apical portion). Oe. planus (9 – 11), Oe. pygmaeus (12 – 14). 9 – 10, 12 – 13, dorsal aspect; 11, 14, lateral aspect. Scales = 0.5 mm (A: 9, 11, B: 10, 12 – 14).