Howeius micropterus, Mantilleri, 2011

Mantilleri, Antoine, 2011, Revision of the Tribe Microtrachelizini Zimmerman, 1994, from Australia: New Taxa and Records (Insecta: Coleoptera, Brentidae), Records of the Australian Museum 63 (1), pp. 89-98 : 93-94

publication ID 10.3853/j.0067-1975.63.2011.1555

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scientific name

Howeius micropterus


Howeius micropterus n.sp.

Type material. HOLOTYPE ♂, Aust: NSW, Lord Howe Island , S. & J. Peck, 17–31.V.1980, Transit Hill, 350', pan traps, lowland tall forest ( ANIC) . PARATYPES: ♀, NSW, Steven’s Reserve Disturbance Gradients, Lord Howe Is., 31°31'25"S 159°04'06"E, 08–15.XII.2000, H. Gibb, R. Harris & T. Moulds, LHI/SR/30/2/1 (pit trap), K192981, pré, MNHN EC1813 ( MNHN) GoogleMaps ; ♀, NSW, Lord Howe Island , Mt Gower, leaf litter, 31°35'S 159°04'E, 100 m, 01.XI.1978, T. Kingston, K188532 ( AMS) GoogleMaps ; ♂, NSW, Mt Lidgbird , SE end in dip between “Pimple” and main cliff, 31°34'18"S 159°05'00"E, 21.V.2001, Ian Hutton, leaf litter ex. leaf litter caught in birds nest fern Asplenium goudeyi , 15 m off ground, K188534 ( AMS) GoogleMaps ; ♂, NSW, Mt Gower , Lord Howe Island, Midway down gully near igloo, 31°35'06"S 159°04'32"E, ca 782 m, 18–31.I.2002, I. Hutton, MG002 (pit trap), K185284 ( AMS) GoogleMaps ; ♂, NSW, in forest behind research station, Lord Howe Island , 31°31'37"S 159°03'58"E, 22.II.2001, Jaynia Tarnawski, LHI/JT/08L, leaf litter ex palm and banyan litter, K188533, MNHN EC1814 ( MNHN) GoogleMaps .

Description. Measurements. Length: 7.6–10.3 mm; width across humeral calli: 0.93–1.40 mm; ratios: length of head + rostrum/length of pronotum: 1.2–1.4; length of pronotum/ width of pronotum: 1.5–2.0; base of pronotum/apex of pronotum: 1.1–1.4; length of pronotum/length of elytra: 0.45–0.55; length of elytra/width of elytra: 2.6–3.0; length of protibia/width of protibia: 4.8–5.3. — Colour. Brownishred to dark brown. — Habitus: Figs 3–4 View Figs 1–8 . — Head ( Fig. 23 View Figs 23–33 ) broader than long, quite convex, smooth, with a deep median notch at the base. Eyes large but not projecting laterally; temples very short, not protruding behind eyes. Vertex and frons smooth. Metarostrum and mesorostrum strongly grooved longitudinally, the groove reaching base of prorostrum; metarostrum with well-marked lateral grooves. Prorostrum smooth, 0.8–1.1× as long as head + metarostrum + mesorostrum. Antennal segment 3 ( Fig. 25 View Figs 23–33 ) conical, 4–8 cylindrical with a row of long raised setae; 9–11 not flattened, forming a club, 11th 1.7–1.8× longer than 10th, acuminated at apex. Venter of head tomentous, metarostrum and mesorostrum and basal half of prorostrum with a longitudinal groove ( Fig. 24 View Figs 23–33 ). — Pronotum cylindrical ( Fig. 23 View Figs 23–33 ), smooth, shiny, grooved only on basal third. Prothorax slightly depressed in front of procoxae; prosternellum hardly distinct. Procoxae bulging, strongly conical. Legs punctate; all femora with yellowish setae on underside (especially in male); meso- and metafemora pedunculate. Protibiae ( Fig. 26 View Figs 23–33 ) 0.8× as long as profemora. Metasternum quite convex, smooth, not grooved. Elytra glabrous, almost completely fused together, the base slightly concave with weak humeral callus. Interstria 2 present almost from base to apex; 3 strongly elevated at base, then more depressed but still distinct, elevated at apex; interstria 4 present from base to apical declivity; 5–6 hardly distinct; 7 more elevated; 8 as 5 and 6; 9 as 7 and forming the external apical border of elytra. Apex of elytra not rimmed nor notched. Mesonotum triangular, its apex pointing upwards. Metanotum weakly sclerotized. Hind wings reduced to small membranous strips.

Sternites III–IV in male ( Fig. 27 View Figs 23–33 ) almost smooth, with few fine punctures and a median longitudinal depression; three large setae on each side of sternite III and one large setae on each side of sternite IV. Spiculum gastrale as in Fig. 23 View Figs 23–33 . Tegmen ( Fig. 29 View Figs 23–33 ) with parameres reduced and filiform, not completely fused. Sternites III–IV in female similar to male, longitudinal depression on sternite III weaker and large setae missing. Tergite VIII denticulate at apex ( Fig. 30 View Figs 23–33 ). Spermatheca as in Fig. 31 View Figs 23–33 . Epipleurites VIII as in Fig. 32 View Figs 23–33 .

Distribution. Recorded only from Lord Howe Island and probably endemic there as its elytra are almost completely fused and its hind wings are not functional.

Etymology. The generic name derives from Lord Howe Island and is masculine in gender, and the specific epithet describes the strong reduction of the hind wings.

Remarks. This new taxon was figured by Zimmerman (1991: 157) under the name Lord Howe Genus A, and listed in his subtribe Trachelizina . However, it belongs to Microtrachelizini as indicated by the structure of the ventral side of the mesorostrum (presence of two small projections under the antennal insertions), the third protarsal segment not being bilobed, sternite VII having two latero-apical depressions, the tegmen being ringshaped with filiform parameres and the gonocoxites of female fused at based, with reduced styli. Its placement in Microtrachelizini is not clear: its elongated prorostrum places it near Araiorrhinus but its elytral venation, apex of elytra and structure of gonocoxites differ strongly from the conditions in Araiorrhinus where there is no strong sclerotization of the apex of gonocoxites (see Fig. 20 View Figs 14–22 for comparison with A. zimmermani and Fig. 49 View Figs 34–50 for comparison with representative of the genus Microtrachelizus ). This new taxon seems to occupy an intermediate position between Araiorrhinus and Microtrachelizus and does not fit with any of the known genera of the tribe. It represents probably a quite old lineage but its presence on Lord Howe Island is surprising as this island is only 6.9 million years old ( McDougall et al., 1981), but exemples exist in other groups of Arthropoda, e. g. in Insecta Hemiptera with the endemic genus Howeria Evans, 1959 ( Burckhardt, 2009) or in Araneae Micropholcommatidae Hickman, 1943 with the endemic monotypic tribe Patelliellini (Rix & Harvey, 2010) . Being an oceanic island, it is very possible that this species derives from a migrant to Lord Howe Island and that the sister-species of H. micropterus still waits to be discovered, probably on the Australian mainland or in New Guinea. Loss of the hind wings in such a short time (less than 6.9 My) is not surprising; it is well documented for other groups of beetles on similar or even shorter periods ( Boucher, 2006).


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