Heterolinus Sharp 1885:475

Márquez, Juan, 2001, Systematic Review Of Heterolinus Sharp (Coleoptera: Staphylinidae: Xantholinini), The Coleopterists Bulletin 55 (3), pp. 317-329 : 318-321

Heterolinus Sharp 1885:475 ; Blackwelder 1944:148 (checklist).

Type Species. Xantholinus puncticeps Guérin­Méneville 1844 (by monotypy).

Diagnosis. Head big, posterior angles acute; superior line of pronotal hypomera joining with inferior line at the procoxae level; elytra strongly rugose at posterior border.

Redescription. Body flattened; length 15–24 mm; black, except abdomen, labial and maxillary palpi, and legs red; or black, except labial and maxillary palpi, and tarsal segments red and two last segments yellow. Head widened posteriorly; lateral margins convex, delimiting clearly dorsal and ventral areas with a fine fold, with a little oblique fold near posterior angles that are acute; posterior margin curved inward; dorsal punctures dense, reduced at frontal area, punctures wide and deep, with two large setae at each middle part of posterior border and with a pair of little setae on central part; with a shallow and wide groove at interior border of each eye that is not a true channel, with microsculpture of wavy lines and some punctures; with frontal and antennal channels, the first one arriving at level of posterior border of the eye and the second one longer; eyes small; antennae long, exceeding middle part of the pronotum when directed backwards; first antennomere longer than next three combined, second longer than half of third, fourth and fifth subquadrate, sixth to tenth transverse, with long setae decreasing to apex and abundant setae increasing to base; mandibles long, nearly as long as head length; labrum conspicuous, long, wide, and bilobed; ventral punctures less dense than dorsal surface; gular sutures contiguous; ventral surface with flat area on each side, as wide as ¼ of total width, finely grooved and very glossy; maxillary and labial palpi moderately long. Neck narrow in proportion to head. Pronotum nearly as long as head length, conspicuously narrower than head; lateral margins narrowed at anterior part; without central punctures or with one, two or rarely three in anterior third; superior line of pronotal hypomera joining with inferior line at procoxae level. Scutellum with few fine punctures. Elytra slightly longer than pronotum; with fine punctures scattered and a row of five setiferous punctures; long setae denser at humeral, lateral, and posterior borders; posterior borders very rugose. Prosternum strongly medially carinate, with carina exceeding procoxae; with conspicuous microsculpture of wavy lines and with fine setae. Mesosternum very short, transverse, widely separating mesocoxae; microsculpture like that of prosternum, with longer setae. Metasternum very long, microsculpture like that of mesosternum, and with long setae denser at sides. Legs moderately long; fifth tarsomere of tarsi as long as previous three combined; fourth shorter; first four tarsomeres of anterior tarsi slightly dilated; protibiae with denser fine setae at inner face and denser and long setae at outer face; with apical and preapical ctenidium; mesotibiae and metatibiae with five ctenidia at inner border. Abdomen short, less than twice as long as elytra; long setae denser at sides, last two segments the densest. Genital segment with male tergite asymmetrical, with denser and fine setae at apex; sternite symmetrical, broader than tergite. Female tergite with few fine setae at apex; sternite divided, with

= 5 mm.

few log setae at apex. Aedeagus elongate, very acute at apex, parameres reduced, internal sac big and conspicuous.

Bionomics. Immature stages are unknown. Little is known about the habitat requirements of the species, but it is probable that they live under bark of dead trees, like the species of the related genera Homalolinus and Ehomalolinus .

Remarks. Species of this genus are superficially similar to species of Homalolinus . They share several features, such as the flattened body, similar size, very long antennae, head broader at base with acute angles, and elytra with fine punctures. Homalolinus canaliculatus and Heterolinus puncticeps are of similar color and maybe sympatric. Heterolinus can be easily distinguished from Homalolinus by its denser punctures on the head, longer antennae, rudimentary ocular channels, lack of impressed Y­shaped line on the head, by the superior line of pronotal hypomera joining with inferior line at procoxae level, the strongly medially carinated prosternum exceeding procoxae, the elytra very rugose at posterior border, first four segments of anterior tarsi slightly dilated, and by the aedeagus with reduced parameres, with conspicuous internal sac.

Geographical Distribution. Species of Heterolinus were previously known from Colombia, Peru, and Costa Rica. In this work, Ecuador and Bolivia are new country records ( Fig. 19 ). Heterolinus basiniger very likely also occurs in Panama.

Figures

Fig. 19. Geographical distribution of the Heterolinus species. Circles = H. basiniger; triangles = H. puncticeps; squares = H. xanthogaster (question mark indicates locality not identified on map).