Lymexylidae, Fleming, 1821

Lawrence, John F., 2020, The Australian Lymexylidae (Coleoptera: Tenerionoidea) with one new genus and two genera new to Australia, Zootaxa 4895 (2), pp. 211-238 : 235

Key to the Genera and Species of Lymexylidae occurring in Australia

1. Elytra covering abdomen or only slightly shortened; hind wings folded beneath elytra; maxillary palp organ absent or present in male only; antennae much longer than head width and more or less serrate..................... Melittommatinae ... 2

- Elytra very short, brachypterous, not reaching metacoxae and exposing all abdominal segments; hind wings exposed, without transverse folds; male and female with maxillary palp organ; antennae not or barely longer than head width and spindle-shaped (widest sub-basally and narrowing towards apex.............................................. Atractocerinae ... 5

2(1). Pronotum not or only slightly longer than wide, widest anteriorly with anterior edge slightly curved and side margins not extending onto apex; anterior pronotal angles obtuse but distinct; antennomeres 3–10 distinctly widened apically; notosternal suture weakly impressed and diagonal; abdominal segment IX in male with appendiculate paratergites; apicale much shorter than basale, apically emarginate but not completely divided; ovipositor with basal coxital lobes evenly, moderately heavily sclerotised, without bacula and with slender mesal projections extending to apex and separating membranous, densely setose apical lobes.................................................................. Melittomma pervagum (Olliff)

- Pronotum distinctly longer than wide, widest at or behind middle with anterior edge strongly curved and side margins more or less continuous with anterior margin; anterior pronotal angles absent; antennomeres 4–10 distinctly widened apically; notosternal sutures distinct and more or less parallel; abdominal segment IX in male without appendiculate paratergites; apicale subequal to or longer than basale, completely divided or not; ovipositor with basal coxital lobes lightly sclerotised, with distinct bacula and without anteromesal projections................................................................. 3

3(2). Base of pronotum without or with broad, shallow impressions; elytral interlocking mechanism and epipleura more or less complete and abdominal apex usually concealed; scutellum at least slightly convex and separated by transverse ridge from scutum; maxillary palp organ present in male; abdominal sternite VIII in male without setose pads.................................................................................................... Alcestoma queenslandicum sp. nov.

- Base of pronotum with pair of small, relatively deep, sublateral impressions; elytral interlocking mechanism and epipleura incomplete, so that elytra beyond middle lie flat on abdomen with independently rounded apices exposing one or two abdominal tergites; scutellum flat or slightly concave, not separated from scutum; maxillary palp organ absent in both sexes; abdominal sternite VIII in male with pair of setose pads................................................ Australymexylon ... 4

4(3). Male antenna strongly serrate; female antenna serrate; penis much shorter than basale and apicale combined; abdominal segment VIII of male with small, round, ventral setose pads; colour almost always with evident pale spot at base of each elytron........................................................................ Australymexylon fuscipennis (Lea)

- Male antenna weakly serrate; female antenna scarcely so; penis as long as basale and apicale combined; abdominal segment VIII of male with large, oval setose pads, covering most of sternite and part of tergite; colour usually uniformly dark, reddishbrown to nearly black..................................................... Australymxylon australe (Erichson)

5 (1). Eyes larger, occupying almost entire frons, separated in frontal view by less than 0.05 times distance across both eyes..... 6

- Eyes smaller, separated in frontal view by at least 0.15 times distance across both eyes.............................. 7

6(5). Head smaller, longer than wide, somewhat horizontally produced, distinctly narrower than pronotum; eyes elongate-oval, their long axis at an angle of about 30º to long axis of head; elytra much shorter than prothorax; northwestern Australia................................................................................... Atractocerus crassicornis Clark

- Head larger, wider than long, rather vertical, at least as wide as anterior edge of pronotum; eyes more diagonal, their long axis at an angle of about 45º to long axis of head; elytra longer than prothorax; southern Australia.................................................................................................... Raractocetus kreusleri (Pascoe)

7 (5). Pronotum subquadrate, not longer than wide; head distinctly declined with vertex somewhat flattened and abruptly declined posteriorly, without median groove; antennae 11-segmented; eyes in frontal view separated by distance about equal to width of one eye in same view; meso- and metatarsi not longer than their respective tibiae; hindwings relatively darkly pigmented, with metallic sheen; northern QLD............................................................... Arractocetus sp.

- Pronotum distinctly longer than wide; head less declined with vertex convex, usually with median groove; antennae 12-segmented; eyes in frontal view separated by distance less than 0.7 times width of one eye in same view; meso- and metatarsi much longer than their respective tibiae; hindwings hyaline, without metallic sheen; southern Australia............................................................................................. Leptonetron victoriense (Blackburn)