Gymnocychramus politus Lea 1921
Creators: name: Lawrence, John F.
name: Kirejtshuk, Alexander G.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Nitidulidae
Gymnocychramus
Gymnocychramus politus

description: Gymnocychramus politus Lea, 1921
(Figs 6, 35–36, 47, 62–63)
Gymnocychramus politus Lea 1921: 185. Type locality: Richmond River, NSW.
Diagnosis. This species differs from G. bicolor in its larger size, brown or black colour, sparser elytral macropunctures, strongly convex prosternum and presence of large, elongate-oval pits on the ventral surface.
Redescription. Length = 4.70–6.20 (5.54 ± 0.54, n = 8) mm. Body ovate, slightly flattened: body length/ elytral width = 1.49–1.54 (1.52); greatest depth/elytral width = 0.56–0.61 (0.58). Head and elytra black, pronotum dark reddish-brown, underside and legs yellowish-brown to black; scutellar shield and pygidium either yellow or dark-reddish brown; antennae usually brownish with darker club. Dorsal vestiture very short and not visible under lower magnifications. Head about as long as wide. Eyes 0.28× head width. Temples 0.52× as long as eye, distinctly curved. Frontoclypeal suture distinct. Clypeus 0.60× as long as wide at base, sides concave and converging to truncate apex. Labrum 0.32× as long as wide. Antennal scape 1.26× as long as wide and 1.93× as long as pedicel; antennomere 3 about 1.5× as long as 4; club 0.60× as long as antennomeres 3–8 combined and 1.31× as long as wide; terminal antennomere 0.74× as long as wide. Mandible with outer edge deeply emarginate at base and strongly, gradually curved towards apex, which is unidentate; incisor edge lined with spines; mola well-developed with a number of transverse ridges; prostheca a narrow membrane becoming broader and setose apically. Apical maxillary palpomere 1.67× as long as wide, widest at base with narrowly rounded apex. Mentum 0.67× as long as wide, parallel-sided; apex biemarginate on either side of subacute mesal lobe. Apical labial palpomere about 1.60× as long as wide, widest near base, with narrowly rounded apex. Genal ridges more or less parallel, only slightly sinuate, extending to ends of temples. Pronotum 0.46–0.51 (0.49)× as long as wide, widest at base, lateral margins visible for their entire lengths from above; anterior edge moderately emarginate forming produced and rounded anterior angles; posterior angles more or less right; posterior edge more or less evenly curved but slightly sinuate laterally, with distinct marginal bead, obscured at middle; disc strongly, evenly convex; punctation fine and sparse, punctures usually separated by more than two diameters; interspaces finely sculptured, with irregular curved ridges, producing a dull sheen. Prosternum 0.95× as long as mid length of procoxal cavity, strongly tumid, without pubescent patch in male; prosternal process 0.48× as wide as mid length of procoxal cavity, not or only slightly curved behind coxae, with angulate apex and distinct vertical wall. Scutellar shield 0.22× as wide as pronotum, with broadly rounded apex. Elytra 1.01–1.07 (1.03)× as long as wide and 1.94–2.33 (2.10)× as long as pronotum; elytral apices independently weakly rounded, but almost meeting at suture, exposing most of pygidium; lateral margins moderately broad and visible for their entire lengths from above; humeri weakly developed; disc with nine more or less regular rows of larger punctures, separated by more than one puncture diameter within a row, with scattered smaller punctures in between, some of them forming less regular rows; fine sculpture similar to that on pronotum but less regular; epipleura slightly oblique and partly visible in lateral view, broad at base and gradually narrowing apically and extending to posterior edge of ventrite 4. Anterior edge of mesoventrite on almost same plane as metaventrite, without posternal rest or median carina, not raised posteriorly, its posterior edge emarginate. Mesocoxae separated by 0.38× longest longitudinal diameter of mesocoxal cavity. Metaventrite slightly convex; distance between meso- and metacoxal cavities 0.32× width of ventrite; discrimen extending almost to base of anterior process; postcoxal lines beginning at about mesal third of each coxal cavity and adjacent to edge of coxal cavity until lateral third, then gradually curving posteriorly to meet lateral edge of ventrite at posterior third; postcoxal lines lined with elongate-oval pits, sometimes acute at one end, and similar pits border the anterior edges of metacoxal cavities. Metanepisternum 4.76× as long as wide, widest near anterior end and narrowed posteriorly. Metacoxae separated by 0.71× mid length (shortest diameter) of coxa. Protibia distinctly expanded apically, its outer edge lined with short serrations, each of which is associated with a short, blunt socketed spine; outer apex with distinct fixed tooth. Mesotibia and metatibia moderately expanded and apically subacute, its outer edge lined with moderately long, acute spines. Anterior faces of meso- and metatibiae each with longitudinally oblique setal row. All basal tarsomeres expanded and lobed, metatarsus less than half as long as metatibia. Abdominal with ventrite 1 at lateral third 0.90× as ventrite 2, with intercoxal process broadly rounded and postcoxal lines shallowly curved and not extending to middle of ventrite; ventrites 2–4 subequal in length, each with one fine transverse carina near anterior end and a more prominent carina just behind it, the latter lined with a series of large longitudinally oval pits; ventrite 5 1.65× as long as 4, with a fine transverse carina near base; apex broadly rounded in both sexes. Pygidium in both sexes with straight transverse basal carina, apex strongly narrowed and truncate. Tergite VIII (anal sclerite) in male apically rounded. Tegmen (Fig. 35) 2.64× as long as wide, its apex strongly curved in lateral view; sides parallel for basal two-thirds, then slightly converging to apex, which consists of two rounded lobes separated by deep incision; side of each lobe with ventral setal tuft; anterior strut 0.37× as long as body of tegmen with narrowly truncate apex; base of tegmen ventrally with pair of short, apically truncate lobes attached to a long, slender strut. Penis (Figs 36, 62–63) slightly longer than body of tegmen and 4.0× as long as wide; distinctly curved at apex; sides subparallel at base, divided apically into broad, lightly sclerotised dorsal lobe with rounded, medially incised apex and ventral lobe about the same length, more heavily sclerotised, widest at base but abruptly narrowed at basal third to form parallel sided process with acute, upturned apex; anterior penile strut about as long as body of penis. Ovipositor (Fig. 47) 1.87× as long as wide, widest at base, flattened; paraprocts slightly longer than gonocoxites, which are 1.12× as long as their combined widths, widest at base and gradually narrowing to subacute, contiguous apices, without gonostyli.
Variation. In a specimen from northern QLD (near Mareeba), the dorsal lobe of the penis bears a distinct recurved tooth arising at the base of the median incision and the ventral lobe is not upturned. It is possible that two species are involved, but the rarity of specimens prevents us from determining whether or not this variation is infraspecific.
Types. Holotype, C/2272, New South Wales, Richmond River, in fungi (QMB); paratype, same data (SAM).
Other specimens examined. NSW: Brindle Creek, Border Ranges N. P. (28.22S, 153.05E), 14.ii.1985, ex ethanol, I. D. Naumann (1, ANIC); Dorrigo Nat. Park, 24.i.1967, on fungus, N. Fenton (3, ANIC, ZIN); QLD: Bartle Frere, west base (17°28’S, 145°46’E), 700m, 10.i–31.iii.1995, Flt. Intercept trap, Monteith & Hasenpusch (1, QMB); Charmillin Ck. Xing, Tully Falls Rd., 950m, 8.xii.1989 – 5.i.1990, pitfall & intercept traps, Monteith, Thompson, Janetzki (1, QMB); Glastonbury Ck., 15 km W of Gympie, 27.x.1980, MV light, A. Neboiss (1, QMB); Julatten, vii.1994, B. P. Moore (1, ANIC); Mapleton Falls NF (26°38’S, 152°51’E), 500m, rainforest, 10.xi.1991 – 8.i.1992, intercept, D. J. Cook (1, QMB); Mossman Bluff track, 5–10 km W of Mossman, 360m, 1–16.i.1989, flight intercept trap, Monteith, Thompson, ANANZSES (1, QMB); Mt. Cotton, upper gully (27°36’S, 153°13’E), 150m, rainforest, 12.xii.1997 – 7.v.1998, 5811, intercept, G. B. Monteith (1, QMB); Mt. Glorious, 630m, 14.xi.1986 – 30.i.1987, flight intercept trough trap, rainforest, T. Hiller (1, ANIC); Numinbah Arch (28°14’S, 153°14’E), 320m, rainforest, 2.xii.1991 – 1.i.1992, intercept, D. J. Cook (1, QMB); Numinbah Arch (28°14’S, 153°14’E), 320m, rainforest, 1.i–23.ii.1992, intercept, D. J. Cook (1, QMB); One Tree Hill, 1.5km NE (25°17’S, 151°55’E), 160m, vine scrub, 6.xii.1998 – 6.ii.1999, 9004, intercept, D. & I. Cook (1, QMB); Ravensbourne NF (27°22’S, 152°11E), 740m, rainforest, 7.i–1.iii.1992, intercept, D. J. Cook (1, QMB); Tamborine Mt., 16.ii.1960, E. M. Exley (4, QMB /UQIC); Tinaroo Creek Rd., 26 km up via Mareeba, MDPI Intercept Trap Site 7, 23.xii.1982 – 12.i.1983, Morgan, Brown, Storey (1, QDPC); Tully Falls, 750m, 8.xii.1989 – 5.i.1990, pitfall & intercept traps, Monteith, Thompson, Janetzki (2, QMB); Yarraman (26°51’S, 152°00’E), 440m, rainforest, 1.xii.1991 – 7.i.1992, intercept, D. J. Cook (1, QMB); Yarraman, Cooyar Ra. (26°52’S, 151°54’E), 540m, rainforest, 2.iii–12.iv.1992, intercept, D. J. Cook (1, QMB).
Distribution. Northern NSW to northern QLD.
Biology. At least one adult of this species has been collected on the fruiting body of Dictyophora indusiata (Vent. Ex Pers.) Desv. (Phallales: Phallaceae) (Lawrence & Milner 1996).
description: Published as part of Lawrence, John F. & Kirejtshuk, Alexander G., 2019, Review of the Australian Cyllodini (Coleoptera: Nitidulidae: Nitidulinae), with descriptions of new taxa, and notes on the genus Macleayania (Nitidulini), pp. 301-334 in Zootaxa 4544 (3) on pages 326-328, DOI: 10.11646/zootaxa.4544.3.1, http://zenodo.org/record/2618373