Elater zealandicus, White, 1846

Redescription (based on O. zealandicus and Lord Howe Island species)

Length 13–20 mm. Elongate and almost parallel-sided, length about 4× width. Elytra almost twice length of head and pronotum. Body uniformly brown to almost black. Body surfaces closely setose, setae short, golden brown and recumbent to semi-erect but easily worn off if specimens handled. Body surfaces shiny, generally closely punctured but without dense microsculpture.

Head. About as broad as anterior of pronotum or distinctly narrower; eye facets minute, much smaller than head punctures; eyes large, prominent laterally, interocular space 2–4.5× eye widths in dorsal view; anterior of clypeus arcuate in dorsal view, abruptly elevated above junction with labrum, edge usually carinate, the deflexed surface punctured and setose; subgenal ridge prominent, continuous from posterior of eye to base of mandible; antennae serrate or pectinate from either 3 rd or 4 th antennomere, if pectinate then with lobes arising from anterolateral angles of antennomeres, shorter than antennomeres; labrum transverse ovate, surface flat to strongly convex, anterior margin convex to feebly medially concave; mandibles short and broad, laterally densely punctured on basal half, bidentate; mentum with convex anteror margin and partly rugose base; apical maxillary and labial palpomeres elongate, almost evenly expanded to obliquely truncate or convex apices.

Thorax. Pronotal length along midline less than width at hind angles; pronotum laterally carinate throughout, carina at anterior angles visible from above or hidden by lateral pronotal swelling; pronotal postero-lateral lobes acute, with a single median carina about 1.5× length of lobe; notosternal sutures sinuate, simple, not grooved, with short anterior notch; pronotal posterior margin not notched inside angles; prosternal chin-piece broadly convex anteriorly, almost flat to strongly reflexed; prosternal process with thin lateral carinae convergent towards apex; scutellum slightly elongate, anteriorly truncate and abruptly elevated; nine regular punctured striae on each elytron and intervals closely but finely punctured; elytral apices rounded, with or without minute tooth at apex of suture; epipleura complete, thin except abruptly expanded at humeri, upper margin continuing as a thin carina along elytral anterior margin; mesocoxal cavities closed by combination of mesoventrite, mesanepisternum, mesepimeron and metaventrite; apices of mesoventral and metaventral intercoxal lobes weakly to strongly bilobed, with deep suture between; metafemora about 2.5× length of metacoxae; paired tibial spurs prominent on each leg; metatarsi slightly longer than metatibiae; tarsomeres 1–4 simple, decreasing in length, 1 about as long as 2+3, 4 not greatly reduced; claws simple, not pectinate, without a ventral seta.

Abdomen. Abdominal process acute between metacoxae; tergite 7 soft, not strongly sclerotised; apex of sternite 7 rounded, truncate or slightly concave.

Female genitalia. Abdominal tergite 8 and sternite 8 fused at base by a sclerotised strip; sternite 8 with spiculum about 2× length of apical field; paraprocts with baculi, long, slightly expanded to anterior apices; gonocoxite partly split into two, proximal piece elongate rectangular, distal piece elongate triangular to rectangular, with subapical laterally directed gonostylus; bursa copulatrix expanded and elongated, with dense small spinules in walls of apical half and a twisted internally microspined extension attached to the base of this spinuliform area; single ovate to sphaerical spermatheca attached by a thin duct to the twisted extension of the bursa copulatrix.

Male genitalia. Posterior margin of tergite 8 convex, sternite 8 partly membranous, without anterior strut, posterior margin concave; tergite 9 without anterior strut, posterior margin concave; tergite 10 distinct but fused to 9 at midline, posterior margin truncate; basal piece roughly U-shaped, with acute anterior angles; parameres free, elongate triangular, laterally strongly acutely barbed, with less than 6 setae at apices; median lobe extending beyond apices of parameres, almost evenly attenuated to apex, with short anterior struts at expanded base.

Sexual dimorphism . Antennomeres 4–10 of females serrate, with triangular antennomeres, antennomeres 4–10 of males with at least slightly extended or lobed apicolateral angles.

Larva (based on two specimens of O. howensis associated with adults; Figs 20–21 View FIGURES 20–21 ). Cylindrical, dorsum with scattered long trichobothrial setae. Head prognathous, flatter than prothorax, anterior margin with small nasale and lateral lobes covering internal base of mandibles; stemmata absent; antennae aparently 2-segmented, with domelike apical sensorium of 2 nd segment much larger than minute third segment; postmentum with truncate posterior edge; prothorax distinctly longer than mesothorax or metathorax; mesothorax and metathorax with narrow anterior band of dense punctures; legs clothed with short stout spines; abdominal segments 1–9 with anterior band of dense punctures and larger lateral punctures, the latter increasing in density from base to apex of abdomen; segments 1–8 each with arched dorsal part distinctly separated from and laterally enclosing almost flat sternite, sides of the dorsal part with a deep but incomplete longitudinal sulcus on anterior 2/3, delimiting fused laterotergite with spiracle; urogomphi absent; tergite 9 cylindrical, dorsal and ventral surfaces not divided, elongate, with 4 longitudinal sulci on basal half, acute apex and 18 rounded tubercles on apical half, five dorsal pairs, one lateral pair and 3 ventral pairs; sternite 9 semicircular, strongly punctured, enclosed by tergite 9.

Notes

The females of the two species examined here have tergite 8 fused to sternite 8, basally (but narrowly), which is supposedly diagnostic for Lissominae ( Calder 1996) . For photography of each sclerite it was necessary to break the sclerotised connecting tissue.

Calder evidently did not examine either O. zealandicus or O. howensis for his diagnosis of Ochosternus ( Calder 1996, pages 23 and 338), as metatarsomere 1 is much shorter than 2–4 combined in these species, and the metatarsi are slightly longer than the metatibia. His description is further confused by illustration of what may be a Megapenthes species to represent Ochosternus ( Calder 1996, Fig. 369). However, Ochosternus is similar to Megapenthes Kiesenwetter, 1858 , a widespread Palaearctic genus with a European type species.

Ochosternus belongs to a group of genera in Australia with the following characteristics: anterior edge of clypeus carinate and strongly elevated above labrum; mandibles bidentate; pronotum entirely laterally carinate; pronotal postero-lateral lobes with a single median carina; pronotosternal sutures simple, not deeply grooved; scutellum anteriorly abruptly elevated; mesocoxal cavities closed by combination of mesoventrite, mesanepisternum, mesepimeron and metaventrite; tarsomeres 1–4 simple, 4 not greatly reduced; tarsal claws not pectinate, without a ventral seta. These are characteristics of the Megapenthini Gurjeva, 1973 ( Stibick 1979). In Australia this group includes six genera: Augenotus Gullan, 1977 ; Lingana Neboiss, 1960 ; Megapenthes Kiesenwetter, 1858 ; Melanoxanthus Eschscholtz in Laporte, 1838, Ochosternus Candèze, 1863 ; Rangsia Calder, 1996 . All are currently placed in Elaterinae ( Lawrence & Slipinski 2013) . Female genitalia in Elateridae are complex and in this group seem to be phylogenetically informative, in contrast to the rather uniformly structured male genitalia ( Calder 1996). The female genitalia of Augenotus quadriguttatus (Erichson, 1842) ( Calder 1996, Fig. 323), Megapenthes automolus Candèze, 1859 ( Calder 1996, Fig. 345) and Ochosternus norfolcensis Lea, 1929 ( Calder 1996, Fig. 370), are almost identical, with a single sphaerical spermatheca on a thin stalk, attached to the twisted and densely internally spined extension of the bursa copulatrix. The females of Lord Howe Ochosternus are similar to these. The male parameres of all three genera are notable for having few apical setae, compared with related genera.

Calder’s descriptions and diagnostic generic key only weakly distinguish Ochosternus from Augenotus and Megapenthes . If these are treated as synonyms, Megapenthes is the oldest name. The putative mainland Australian Ochosternus specimens in Queensland Museum, mentioned above, appear to be the same as specimens in the Australian Museum identified as Megapenthes or ‘near Megapenthes’ by Calder and Goodyer. However, Megapenthes is based on a European type species and its Australian species may be wrongly placed in this genus. For example, Asian species that might otherwise belong to Megapenthes have been split into several genera based on subtle differences in shape of the elytral apices ( Schimmel 2004). Taxonomy of the Megapenthes generic group clearly needs more work. For purposes of this faunistic study, we consider the Lord Howe species of this generic group to be correctly placed in Ochosternus .