Bolitogyrus proximus (Cameron, 1942)

Brunke, Adam J., 2017, A revision of the Oriental species of Bolitogyrus Chevrolat (Coleoptera, Staphylinidae, Staphylininae), ZooKeys 664, pp. 1-97 : 21-22

Bolitogyrus proximus (Cameron, 1942) Fig. 1D, 3B, 10 D–G, 19D (map)

Cyrtothorax proximus Cameron, 1942: 138

Type locality.

Martapura, South Kalimantan, Borneo, Indonesia.

Type material.

Cyrtothorax proximus Cameron, 1942.

Holotype (♂, BMNH). Type [circle label with red border] / Martapura, S.E.

Borneo, Doherty, 1891 [printed] / C. proximus TYPE Cam. [handwritten] / M. Cameron. Bequest., B.M. 1955-147 [printed] / Holotype ♂, Cyrtothorax proximus Cameron, 1942, det. A. Brunke 2017 [red printed label] / AJB0000399 [identifier label].

Cameron (1942) stated that his specimen was a female, though it is a male.

Other material.

BRUNEI: Temburong: Kuala Belalong FSC, 4°34'N 115°7'E, malaise GM3, 18.V.1991, N. Mawdsley, 1 ♀, AJB0000498 (BMNH).

MALAYSIA: Sabah: Batu Punggul Resort, environs of, vegetation and forest floor litter around large trees near river, 24.VI-1.VII.1996, 1 ♀, AJB0000493 (MHNG); same except, intercept trap, 23-V-2001, J. Kociam, 1 ♀, AJB0000497 (NMW); Danum Valley, B.R.I., flight intercept trap, 14-16.II.2007, G. de Rougemont, 1♂, AJB0000488 (cRou); same except, 1.VI.1999, G. Mendel, 1 ♀, AJB0000492 (BMNH); Lahad Datu, Ulu Segama, Forest Reserve, Danum Valley F.C., 4°57.9'N 117°48.1'E, 200 m, 1° forest, flight intercept trap, 4.IV.2005, E. Slade and Villaneuva, 1 ♂, AJB0000489 (OUMNH); same except 1.XI.2005, 1 ♂, AJB0000490 (OUMNH); Penanpang, flight intercept trap, 11-15.I.2008, Y. Shibata, 1 ♀, AJB000091 (cShi); Sepilok Nature Resort, in fungi on log, 13.II.2007, G. de Rougemont, 1 ♀, AJB0000487 (cRou); Tawau Hills Park, 7-9.VI-1998, P. Hlavac, 1 ♂, AJB0000400 (NMW); Sarawak: Gunung Mulu National Park, near base camp, 50-100 m, alluvial forest, malaise trap, V-VIII.1978, P. Hammond and J. E. Marshall, 1 ♀, AJB0000496 (BMNH).

INDONESIA: Central Kalimantan: confluence of Busang and Rekut rivers, flight intercept trap, VIII.2001, Brendell and Mendel, 1 ♂ 1 ♀, AJB0000494, AJB0000495 (BMNH); East Kalimantan: Paiau River, Mjöberg, 1 ♂, NHRS-JLKB-000021956 (NHRS).

Diagnosis.

Among the members of the Caesareus Group: pronotum not entirely pale; elytra without dark spot; first two visible abdominal segments with distinct darkened area (Fig. 1D); median lobe in parameral view converging to acute apex (Fig. 10D).

Redescription.

Measurements ♂ (n = 5): HW/HL 1.34-1.42; PW/PL 1.39-1.46; EW/ EL 1.21-1.25; ESut/PL 0.86-0.90; PW/HW 1.10-1.13; forebody length 6.1-6.5 mm.

Measurements

♀ (n = 5). HW/HL 1.39-1.48; PW/PL 1.32-1.41; EW/ EL 1.22-1.24; ESut/PL 0.88-0.94; PW/HW 1.06-1.09; forebody length 5.9-6.5 mm.

Similar to B. caesareus but differing only in the following: antennae with apical 1 or 2 segments distinctly paler, first segment entirely yellow; orange area on frons distinctly larger, reaching up to half the length of eyes; scutellum varying from entirely reddish to basal two-thirds dark brown; palpi with last segment darkened; pronotum not entirely pale and always dark medially with pale expanded margin: sometimes with a spot in each orange lateral area, sometimes pronotum with only anterior angles paler, or pronotum entirely dark; antennomeres 7-10 transverse and asymmetrical; elytra slightly shorter relative to pronotum at middle; elytral disc with small, variably-shaped, elevated and impunctate yellow spot; pronotum wider relative to head; pronotal margin distinctly more expanded; elytral disc with setose punctures only in usual rows; sternites III-V with basal line distinctly projected posteriad at middle; median lobe in lateral view slightly constricted just before apex, this part slightly deflected dorsad, with tooth basad of constriction, this tooth arising from middle of subapex, not apical carina (Fig. 10F); median lobe in parameral view sometimes with slight ridge connecting apex with tooth (Fig. 10E); paramere slightly longer than median lobe, much more strongly constricted at basal third and more strongly expanded about midlength, peg setae similar but more clearly separated into marginal and medial groups, sometimes connecting to form a pair of ovoid shapes (Fig. 10G); male sternite VII additionally with glabrous triangular area medioapically; male sternite IX with regular setation, without conspicuous rows of long setae; female tergite X triangular with acute apex, with raised, flat discal area of approximately same shape.

Distribution.

Figure 19D. Endemic to the island of Borneo. The single specimen from Brunei is a female but is tentatively assigned to this species as it was collected at a lower elevation than those of the externally indistinguishable B. temburong .

Bionomics.

Like the often co-collected B. caesareus , B. proximus is a species of lowland rainforests in Borneo. Several specimens indicate large trees or primary rainforest on the labels. Specimens have been collected during the months of January-February, April-August, and November, in flight intercept traps and from litter at elevations ranging from 0-200 m. Bolitogyrus proximus has been frequently collected along larger rivers, while its cryptic sister species, B. temburong occurs in lower montane forests (>400 m).

Comments.

Although externally indistinguishable from B. temburong , B. proximus differs dramatically in the shape of the paramere and the median lobe in lateral view; it may also be micro-allopatric with it at a lower elevation.