Ochthebius queenslandicus Hansen, 1998

Perkins, Philip D., 2007, A review of the coastal marsh water beetle Ochthebius queenslandicus Hansen (Coleoptera: Hydraenidae), Zootaxa 1625, pp. 35-42 : 37-40

Ochthebius queenslandicus Hansen, 1998

( Figs. 1–6 )

Ochthebius pallidipennis Deane 1931: 169 (primary homonym of O. pallidipennis Villa & Villa, 1835 [= O. aeneus Stephens, 1835 ].

Ochthebius queenslandicus Hansen 1998: 118 (replacement name for Ochthebius pallidipennis Deane, 1931 ). Ochthebius queenslandicus Hansen ; Jäch, 2001: 103 (redescription).

Type Material. Holotype (female): AUSTRALIA: Queensland: Townsville [labels: Townsville N. Q. G. F. Hill // 2275 TYPE // Ochthebius pallidipennis Deane ; F. E. Wilson collection // DIGITAL IMAGE captured 2004 P. D. Perkins]. Deposited in the MVMA.

Diagnosis. Recognized from other Australian hydraenids by the combination of short maxillary palpi, pronotum with a lateral hyaline border, and elytra with dark brown longitudinal lines passing through the serial punctures ( Fig. 1 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.85/0.78; head 0.34/0.45; pronotum 0.45/0.62; elytra 1.05/0.75. Head and disc of pronotum infuscate or blackish, slightly metallic, lateral areas of pronotum slightly lighter, elytra brownish or testaceous with brownish longitudinal lines through at least series 1 to 7 or 8, lines sometimes reduced anteriorly and posteriorly over series 1 to 3, lines sometimes indistinct in darkly colored specimens; maxillary palpi and legs light brownish to testaceous, venter dark brown to black.

Eyes in dorsal aspect with eight convex facets in longest series. Interocular foveae large and deep, medial margin more abrupt than lateral, width of each nearly equal distance separating them. Ocelli distinct, shining. Frons finely sparsely punctulate, interstices shining except duller in microreticulate areas anteromedially and especially at sides of interocular foveae. Clypeus strongly microreticulate and dull laterally and basally, remaining sub-triangular median area shining, finely sparsely punctulate; anterior angles of clypeus slightly declivous, slightly produced, acute. Frons and clypeus punctures each with fine short indistinct recumbent seta.

Pronotum widest near anterior 1/4, side attenuate, weakly sinuately so to base. Anterior margin on each side with minute postocular process and extremely shallow postocular emargination; hyaline border well developed; posterior to hyaline border transversely narrowly banded with smooth strongly shining area. Lateral hyaline border moderately wide, sides almost straight, anteriorly narrowing and ended just behind anterior angles, posteriorly continuing narrowly but distinctly around posterior angles and along base. Disc with microreticulate narrow midlongitudinal sulcus shallower and less strongly, if at all, microsculptured in midlength; anterior and posterior admedian foveae well developed, punctate, microreticulate and confluent with similarly microsculptured sulcus, posterior foveae larger than anterior; reliefs shining, submedially very finely sparsely recumbent-setiferously punctate and with exceeding fine, sparse, irregularly distributed micropunctate ground sculpture. Lateral depression, lateral fossula and area between fossula and posterior fovea more densely coarsely punctate than discal reliefs. Posterior angle with broad shallow depression.

Elytra elongate oval, broadest about middle. Each elytron with ten distinct series of punctures, series not striate-impressed except sutural in discal 1/2, puncture diameter ca. 1.5 times eye facet on disc, longitudinally separated by less than puncture diameter, becoming finer and more separated laterally and apically, each puncture with fine recumbent nearly imperceptible seta. Intervals flat, 2 to 3 times puncture diameter, slightly shining, very effacedly alutaceous; sparse nervure setae each with base dark brown similar to serial punctures.

Metaventrite with large median, sub-triangular, shining glabrous area, except a few random punctures in middle of glabrous area.

Aedeagus ( Figs. 2 ) with distal piece thin and markedly arcuate.

Sexual dimorphism: Labrum (microslide mount) in male medially slightly depressed and non-setose, submedially on each side bearing four to six short, stout spines facing inward, laterally bearing tapering setae, surface microreticulate, anterior margin nearly entire, moderately strongly reflexed over median 1/2, free edge of reflexed part straight. Labrum in female with anterior margin straight or very weakly arcuate, surface microreticulate and bearing rather dense, tapering setae. Mandible in male with outer margin bearing stout, rather long spiniform setae; in female, with tapering curving setae. Explanate margin of elytron in male narrower than tarsal apex, in female as wide as tarsal apex. Elytral apices in male narrowly separately rounded, in female conjointly rather sharply rounded. Abdominal ventrites as follow: 1–5 entirely clothed with dense hydrofuge pubescence in both sexes, except small shining posteromedian area on ventrite 5 in female; ventrites 6 and 7 microreticulate; ventrite 6 apical 1/ 2 in male sparsely, in female densely setose; ventrite 7 in male apically setose on each side of median emargination, in female setose over median 1/2 of arcuate margin. Apical tergite sharply rounded, in male bearing tapering setae, in female bearing tapering setae and margin with fringe of short stout spines. Male protarsomeres 1–2 with pad of suction setae.

Distribution. Currently known from coastal or near-coastal localities near the cities of Perth, Darwin, Karumba, and Townsville ( Fig. 6 ).

Discussion. The size, pronotal microsculpture, and elytral color vary considerably in this species. Larger specimens (ca. 1.80 mm), such as the holotype and other specimens from near Townsville, Queensland, are generally darker and slightly more strongly sculptured on the pronotum. Smaller specimens (ca. 1.62 mm), such as those from Holmes Jungle (near Darwin in the Northern Territories), often have the lines of color on the elytra less developed anteriorly and posteriorly over the medial series, but the other series are more distinctive than the same in larger specimens due to a paler testaceous background. In general, the lines of color are in part a product of the spacing of the serial punctures, that is, each puncture has a "dot" of dark color and when the punctures are longitudinally close enough together the dots become confluent to form the lines of color. The pronotal microreticulation in the area of confluence of the midlongitudinal sulcus and posterior foveae is usually well developed in small specimens, but appears to vary more in larger specimens. The aedeagal structure differs only very slightly among the various morphs ( Figs. 2–5 ). A polymorphic interpretation is considered prudent given the aedeagal uniformity, the lowland coastal distribution, and the few specimens available for study.

Material (36 examined). AUSTRALIA: Northern Territory: Darwin, 12° 27' S, 130° 50' E, 13 May 1963, C. Watts (2 females SAMA); Holmes Jungle, 11 km NE by E of Darwin, 12° 24' S, 130° 56' E, 15 May 1973, M. S. Upton (3 males, 7 females ANIC); Howard Springs, 24 km S of Darwin, 12° 28' S, 131° 3' E, 12 May 1983, J. T. Doyen (1 male ANIC); Howard Springs, 14 May 1963, C. Watts (1 female SAMA); Queensland: Near Karumba, 17° 29' S, 140° 52' E, 4 November 1968, D. D. Giuliani (1 male, 1 female WAM); Normanton, at light, 17° 40' S, 141° 4' E, 4 September 1982, R. I. Storey (1 male, 1 female QPIM); Normanton, at light, 17° 40' S, 141° 4' E, 4 May 1963, P. F. Aitken and N. B. Tindale (1 female SAMA); Townsville, light trap, 19° 15' S, 146° 48' E, 23–30 May 1968, P. Ferrar (1 male ANIC); same locality, 19° 15' S, 146° 48' E, 31 May–16 June 1968, P. Ferrar (1 female ANIC); Townsville [no date], 19° 15' S, 146° 48' E, G. F. Hill (holotype) (1 female MVMA); Townsville, Town Common, shallow pools in seasonally flooded marshland, 21 March 1996, J. Denton (6 NMW; not seen); Western Australia: Cannington, 32° 1' S, 115° 56' E, 24 July 1953, R. P. McMillan (1 male WAM); L. Walyungup, 32° 20' S, 115° 46' E, 1–30 March 1972, P. Zwick (1 male MCZ); Mandurah, 32° 31' S, 115° 43' E, 17 April 1975, F. H. Uther-Baker (1 male ANIC); Rottnest Island, 32° 0' S, 115° 36' E, 1–30 October 1931, P. J. Darlington (1 MCZ); Vasse [no date, no collector], 33° 41' S, 115° 17' E (5 males, 5 females SAMA).

Figures

FIGURE 1. Ochthebius queenslandicus, holotype. Dorsal and lateral habitus.

FIGURES 2 – 5. Ochthebius queenslandicus, aedeagi. 2. Specimen from Townsville, Queensland. 3. Specimen from Vasse, Western Australia. 4. Specimen from Holmes Jungle, Northern Territories. 5. Specimen from Karumba, Queensland.

FIGURE 6. Geographical distribution of Ochthebius queenslandicus.