Prototympanogaster lordhowensis, Perkins, 2018

Perkins, Philip D., 2018, A new genus and new species of Meropathina from Lord Howe Island (Coleoptera: Hydraenidae), Zootaxa 4444 (4), pp. 409-420 : 410-413

Prototympanogaster lordhowensis , new species

Figs. 1 (habitus), 20 (aedeagus), 29, 30 (habitat)

Type Material. Holotype (male): " Lord HoWe Island , Mount Lidgebird, E side nr rope 31.573S 159.084E leaf litter ex Pimelia, Cassinina & Metrosideros 7.III.2003 I Hutton IH 048C"; deposited in the Australian Museum, Sydney . Paratype: One male, same data as holotype, also deposited in the Australian Museum.

Differential Diagnosis. Differentiated from species of Tympanogaster by the lack of a metaventral tabella.

Description. Habitus as illustrated ( Fig. 1). Size: holotype (length/Width, mm): body (length to elytral apices) 2.48/1.10; head Width 0.58; pronotum 0.64/0.87, Width of anterior margin 0.63, Width of posterior margin 0.66; elytra 1.49/1.10. Dorsum and venter dark broWn to black, legs dark broWn. Dorsum With conspicuous short Whitish setae.

Head With frons and clypeus densely, coarsely punctate, each puncture With short seta, punctures on frons deep, separated by narroW Walls lacking microsculpture. Eyes moderately large, in dorsal aspect With 6–7 facets in longest series. Frons disc nearly flat betWeen deep longitudinal interocular foveae; ocelli prominent. Frontoclypeal suture deep, rather Wide, bisinuate. Clypeus With sides moderately raised, disc Weakly convex, anterior angles slightly deflexed, and Weakly produced, anterior margin very Weakly arcuate betWeen angles. Labrum microreticulate, ca. 1x and at angle to clypeus, apicomedian notch large, lobes prominent, reflexed, margin slightly thickened and With short setae.

Pronotal disc convex, more so transversely than longitudinally. Anterior margin very Weakly arcuate, almost straight, median 1/3 With very narroW hyaline border, postocular emarginations lacking. Lateral margins arcuate, posteriorly very Weakly attenuate to obtuse posterior angles. Posterior margin Weakly bisinuate, ca. median 1/3 With very narroW hyaline margin. Pronotal reliefs densely coarsely punctate, each puncture With short seta. Areas With feWer, or no punctures, include median longitudinal groove, anterior and posterior shalloW admedian depressions, moderately deep longitudinal groove on each side that delimits lateral lobe, groove continuing to posterior angles, and lateral lobes. Surfaces Without punctures smooth and shining, lacking microsculpture.

Elytra With sides Weakly arcuate to about middle, then gradually attenuate to conjointly rounded apices; margins With more-or-less unilinear roW of short setae; explanate margin moderately Wide, cuticle smooth, Without punctures, ended slightly before apices. Each elytron With ten roWs of large, closely spaced serial punctures, each With short but conspicuous recumbent seta. Disc With shalloW saddle located just before summit of posterior declivity, saddle occupying first four roWs of serial punctures. Interval Width ca. 1– 2x Width of roWs of punctures; sutural interval and intervals 2, 4 and 6 raised, at least in part, 2 and 6 very loW, 6 higher at lateral margin of saddle, each raised part With setigerous micropunctures, not in unilinear roWs. Other intervals smooth and shining.

Venter: Mentum rectangular, length slightly greater than Width, as ca. 7/6; disc Weakly concave, finely sparsely punctate and effacedly microreticulate. Prosternum non-carinate. Mesosternal process slightly tumid. Metaventrite transversely convex, entirely hydrofuge pubescent, With a very shalloW and narroW midlongitudinal impression in the basal 2/3.

Abdomen: First five ventrites With hydrofuge pubescence similar to that on metaventrite. Last tWo ventrites shining, With sparse setae.

Aedeagus: Lacking parameres; gonopore at end of coiled flagellum ( Fig. 20).

Etymology. Named in reference to the knoWn distribution.

Remarks. This species is brachypterous: the Wings are not folded, and the Wing length is slightly less than the elytron length.

The distal portion of the aedeagus is similar in structure, but not shape, to the aedeagus of Tympanogaster (Topotympanogaster) intricata Perkins, 2006 . The distal piece has the striated duct surrounded by a sclerotized, very asymmetrical sheath, and the duct continues beyond the sheath as a coiled flagellum. Other species of Topotympanogaster have the striated duct Within a comparatively symmetrical tube-like distal process, and do not have a flagellum.

T. intricata is the only species of Tympanogaster knoWn to have a similar aedeagal form. Externally, T. intricata differs markedly from P. lordhowensis : (a) the metaventrite has a large glabrous tabella, as is characteristic for members of Tympanogaster ; (b) the pronotum has six distinct longitudinal ridges; and (c) the even numbered elytral intervals are carinate. In general aspects, P. lordhowensis is flatter, has a more ovate disclike pronotum, has a different head shape With a rather Wide and deep fronto-clypeal suture that is bisinuate (in T. intricata the lateral margins of the frons are more convergent anteriorly, and the fronto-clypeal suture is arcuate), and P. lordhowensis is larger in body size (length ca. 2.48 vs. 1.43 mm)