Bolitogyrus cornutus Brunke

Brunke, Adam J. & Solodovnikov, Alexey, 2014, A revision of the Neotropical species of Bolitogyrus Chevrolat, a geographically disjunct lineage of Staphylinini (Coleoptera, Staphylinidae), ZooKeys 423, pp. 1-113 : 42-44

Taxon classification Animalia Coleoptera Staphylinidae

Bolitogyrus cornutus Brunke sp. n. Figs 2B, 8 C–F, 21 A–D, 24E, 27D, 31A (map)

Type locality.

Ecuador, Pichincha, Mindo.

Type material.

Holotype ♂ (SEMC): ECUADOR: Pichincha, Mindo, 10.6 km, W. Mindo Road, 0°4'23"S, 78°45'14"W, 1375 m, 28 Mar 1999, R. Brooks, ECU1B99 061, ex. fungus covered log [white printed label] / SM0153248 [white barcode label] / Holotype, Bolitogyrus cornutus Brunke, sp. n. [red printed label].

Paratypes (5 ♂ 5 ♀, SEMC, ZMUC): same data as holotype, SM0153249, SM0153250, SM0153252, SM0153253, 3 ♂ 1 ♀ (SEMC, ZMUC). COLOMBIA:Valle de Cauca, PNN Farallones de Cali Anchicaya, 3°26'N, 76°48'W, 730 m, Malaise, 27.II to 27.III.2001, S. Sarria leg., M.1538, SM0548927, SM0548929, 1♂ 1♀ (SEMC); same locality except: 1.VIII to 10.X.2000, M.1104, SM0548928, 1 ♀ (SEMC); same locality except: 9.V to 18.VII.2000, M.1099, SM0548926, 1 ♀ (SEMC); same locality except: 8.V to 19.V.2001, M.1893, SM0548930, 1 ♂ (SEMC); same locality except: 900 m, 19.VI to 3.VII.2001, M.1891, SM0650434, 1 ♀ (SEMC).

Diagnosis.

Within the Bullatus Lineage: pronotum with two punctures in dorsal row (Fig. 7C); abdominal segment VIII pale yellow, distinctly paler than previous segments (Fig. 2B). Most male specimens can be recognized immediately by the protuberance of the pronotum produced into a truncate ‘horn’ (Fig. 8C).

Description.

Measurements ♂ (n=5): HW/HL 1.98-2.10 ( ‘pseudofemale’ with 1.90); PW/PL 1.66-1.85; EW/EL 1.26-1.32; ESut/PL 0.79-0.82; PW/HW 1.12-1.17; forebody length 3.8-4.3 mm.

Measurements ♀ (n=5): HW/HL 1.76-1.86; PW/PL 1.49-1.70; EW/EL 1.23-1.29; ESut/PL 0.86-0.96; PW/HW 1.04-1.07; forebody length 4.0-4.4 mm.

Coloration: body dark brown; frons sometimes with faint, green-blue metallic reflection; pronotum with faint bronze metallic reflection; pronotum with base narrowly, and lateral portions broadly and distinctly paler, orange-brown, pronotal protuberance paler, pale lateral areas sometimes joining with that on pronotal protuberance; elytra paler, reddish brown to yellowish-brown with epipleuron distinctly paler, yellowish, suture and outline of scutellum dark brown, apex of elytra indistinctly to noticeably paler; dorsal abdomen with tergites III–V reddish brown to red, bordered laterally and apically with contrasting dark brown in specimens from Ecuador, tergites more diffusely colored in Columbian specimens; tergites VI–VII darker, dark brown, apex of tergite VII with pale, orange semi-circular marking, apex of sternite VII pale, yellow; segment VIII and genital segment of both sexes entirely pale, yellow; antennomeres I–V pale, yellowish brown, segments I–II sometimes darker brown, antennomeres VI–X dark brown, apical antennomere slightly paler than previous, light-brown to brownish-yellow; maxillary and labial palpi yellow-brown, segments I–III darker in specimens from Ecuador; legs pale, yellow to yellowish brown, profemur without distinct dark subapical band, meso- and metafemur with dark subapical band nearly or entirely reaching apex, mid and hind coxa darkened, brownish, tibia with darkened lateral face, tarsus dark brown.

Head markedly more transverse in males than in females; with median frontal impression present and always distinct; frons coarsely sculptured but strongly glossy; base of head with well-developed posterior protuberances, surface smooth, glossy, with several coarse, sparsely distributed, asetose punctures; microsculpture absent dorsally except as broken lines on frons in some specimens and well-developed, fine lines on temples.

Pronotum markedly more transverse in males than in females; with disc smooth, glossy, with scattered fine to coarse micropunctures on disc, microsculpture absent except as broken lines on anterior angles; lateral areas with moderately impressed, irregularly spaced, asetose punctures, often contiguous; pronotal protuberance in lateral view distinct in both sexes but weakly to moderately developed in females (Fig. 8E), and strongly developed and truncate apically in males (Fig. 8C) (one male seen without strongly developed pronotal protuberance); lateral margins of pronotum strongly convergent anteriad in females and more weakly convergent anteriad in males but of a shape distinct from species of the Divisus Group (Fig. 2B); with two punctures in dorsal row; scutellum with 1-5 separated to contiguous, weakly impressed, asetose punctures; elytra weakly transverse, suture shorter than to nearly equal to pronotum at midlength; macrosetae of elytra relatively long and erect, distinct from overall surface sculpture in lateral view.

Median lobe entire, with more heavily sclerotized areas indicating two lateral lobes with subapical teeth (Fig. 21C); in lateral view, median lobe constricted at midlength, produced ventrad and then recurved dorsad (Fig. 21C); paramere reaching level of constriction of median lobe, in lateral view; in parameral view, median lobe slightly dilated in apical third, apex weakly to distinctly notched (Fig. 21A); paramere truncate to notched apically, narrowed at midlength and apical third dilated, without peg setae, apex with a row of fine setae (Fig. 21 A–B, D). Male sternite VII without emargination, with only narrow glabrous area at middle; male sternite VIII with transverse basal line broken at middle, with slightly emarginate apex, impressed and glabrous in short triangular area near emargination; male sternite IX distinctly asymmetrical at base, with deep emargination at apex (Fig. 24E).

Female tergite X strongly constricted in basal half, base fused with accessory sclerite, with U-shaped emargination at apex (Fig. 27D); female laterotergal sclerites expanded at base and overlapping with tergite X (Fig. 27D).

Distribution.

Figure 31A. Known from the foothills of the Andes in Columbia and Ecuador. Bolitogyrus cornutus is the only species of the genus known to occur in South America and may occur farther north in Venezuela.

Bionomics.

Specimens of Bolitogyrus cornutus have been collected from elevations ranging from 700-1375 m, from fungus-covered logs and from Malaise traps during February to March and May to October.

Etymology.

The species epithet refers to the strongly developed pronotal protuberance of male Bolitogyrus cornutus . This species possesses the most strongly modified pronotum in the genus Bolitogyrus .

Comments.

Bolitogyrus cornutus is currently the only species of the genus known from South America and thus, can be recognized by distribution alone. One unassociated female (BMNH) from the vicinity of the type locality may belong to this species but, as it was collected at a substantially higher elevation (1700 m), remains unidentified.

The sexual dimorphism of the pronotum observed in this species is striking and the most pronounced in the entire genus (Fig. 8 C–F). However, one male specimen from Columbia was observed with some female-associated characters including a pronotum with a small and rounded protuberance (Fig. 8D) and a less transverse head (1.90 versus 1.98-2.10 in other males). It is also smaller than the other males but size was not found to be sexually dimorphic in this species (see measurements). Its aedeagus is identical to that of other males from the same collecting event, suggesting that males of Bolitogyrus cornutus may be polymorphic for secondary sexual traits and possibly any behavior related to them.