Hydraena impercepta Zwick, 1977

Perkins, Philip D., 2011, New species (130) of the hyperdiverse aquatic beetle genus Hydraena Kugelann from Papua New Guinea, and a preliminary analysis of areas of endemism (Coleoptera: Hydraenidae) 2944, Zootaxa 2944 (1), pp. 1-417 : 102-104

Hydraena impercepta Zwick, 1977

( Figs. 178 , 180 , 346–348 , 409 , 515, 516 )

Hydraena impercepta Zwick, 1977: 153 .

Hydraena impercepta ; Perkins 2007: 62.

Type Material. Holotype (male): Queensland [labels: Queensland Blackb's Coll // luridipennis, Macl. // I 8298 Hydraena luridipennis Macl Queensland // // Hydraena impercepta Zwick spec. nov. Holotypus male design. P. Zwick 1975 // DIGITAL IMAGE captured 2004 P. D. Perkins] ( SAMA).

Differential Diagnosis. Differentiated from H. cavifrons by the non-concave frons and the comparatively small metaventral plaques, which are small ovals (SEM Fig. 346 ). The plaques are similar to those of H. buloba ; differentiated from that species by the very differently shaped pronotum that has much less angulate sides, and is less transverse (PL/PW ca. 0.73 vs. 0.50), the less robust body, and the non-striate-impressed elytral series ( Figs. 178 , 179 , 182 ). The pro- and metatibiae of males differ in all three species of the Luridipennis group in PNG, and the male genitalia distinctively differ ( Figs. 180, 181 , 184 ). The metaventrite, abdominal apex, and complicated chaetotaxy of the tibiae are illustrated with SEMs ( Figs. 346–348 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.00/0.88; head 0.25/0.45; pronotum 0.49/0.64, PA 0.49, PB 0.59; elytra 1.29/0.88. Head and large pronotal macula dark brown, remainder of dorsum, legs and maxillary palpi brown.

Frons punctures ca. 1xef; interstices narrow walls near eyes, 1–3xpd medially. Clypeus microreticulate laterally, finely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotum densely coarsely punctate, punctures on disc deep, ca. 3xpd those of frons, interstices narrow walls to 1xpd, some interstices uniting to form short longitudinal lines; PF1 absent; PF2 shallow; PF3 and PF4 moderately deep, shallowly joined.

Elytral punctures about 0.5xpd of largest pronotal punctures. Intervals not raised, width ca. 1xpd, interstices between punctures of a row slightly less. Apices in dorsal aspect separately rounded, in posterior aspect margins forming angle with one another.

Metaventral disc densely punctate beneath hydrofuge pubescence, without plaques, median impression deep, longitudinal, subtriangular, basally ca. 2x P2. P1 laminate; median carina angulate in profile. P2 moderately narrow, l/w ca. 5/3, sides parallel, apex rounded. Very low midlongitudinal carina between mesoventral intercoxal process and median depression. AIS flat, width at arcuate posterior margin 2x P2. Abdominal apex with short setae; last tergite with depression on ventral face. Protibia with subapical angulation on inner surface. Mesotibia slender. Metatibia with rounded enlargement on inner surface near midlength, then tapering to apex; outer surface arcuate at base, then straight to apex.

Aedeagus ( Fig. 178 ) main piece slightly wider in lateral than ventral view, with large, strong process on right side of apical part, medial margin with two points; left paramere large, with four groups of setae; right paramere narrow, with three groups of setae. Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 409 ); tergite X with row of stout setae, tips blunt and angled ventrad.

Distribution. In PNG, known from lowland Areas 3, 11, and 15; elevation range 20–305 m ( Fig. 516 ). Also known from Australia, having a wide distribution pattern in Queensland and northern Northern Territory ( Fig. 515 ).

Remarks. In females the elytral apices are slightly more sharply rounded, the posterior declivity is not as abrupt, and the metaventral depression is not as deep as in males. Some specimens have the metaventral plaques apparent as very small, non-punctate ovals at the base of the median depression.

Material Examined (92): Central Province: Loloki , 10 miles N of Port Moresby, ex gravel in roadside drain, [GE est.] 30–50 m, 9° 20' S, 147° 10' E, 19 iii 1965, M. E. Bacchus (MEB 209) (2 NHM) ; Loloki , 10 miles N of Port Moresby, ex swamp, much grass, [GE est.] 30–50 m, 9° 20' S, 147° 10' E, 19 iii 1965, M. E. Bacchus (MEB 208) (2 NHM) ; Moitaka , 7 miles N of Port Moresby, among vegetation hanging from bank into deep pool in field drain, [GE est.] 30–50 m, 9° 25' S, 147° 12' E, 17 iii 1965, M. E. Bacchus (MEB 205) (m# NHM) ; Moitaka , 7 miles N of Port Moresby, ex dead leaves in gravelly shallow of small pond, [GE est.] 30–50 m, 9° 25' S, 147° 12' E, 17 iii 1965, M. E. Bacchus (MEB 207) (4 NHM) ; Moitaka , 7 miles N of Port Moresby, ex shallow muddy margin of swamp, little weed, [GE est.] 30–50 m, 9° 25' S, 147° 12' E, 17 iii 1965, M. E. Bacchus (MEB 203) (1 NHM) ; Moitaka , 7 miles N of Port Moresby, ex weeds round margin of small pond, [GE est.] 30–50 m, 9° 25' S, 147° 12' E, 17 iii 1965, M. E. Bacchus (MEB 207a) (1 NHM) ; Moitaka , 7 miles N of Port Moresby, shallow grassy margins of swamp, [GE est.] 30–50 m, 9° 25' S, 147° 12' E, 17 iii 1965, M. E. Bacchus (MEB 206) (19 NHM) ; Port Moresby – Brown River road, ex grassy shallows of large muddy pond, [GE est.] 50–100 m, 9° 24' S, 147° 14' E, 15 iii 1965, M. E. Bacchus (MEB 195) (30 NHM) ; Madang Province: 5 km N Brahman , [GE est.] 130–150 m, 5° 39' S, 145° 22' E, 21 vi 1991, D. Larson (1 MCZ) ; Ramu Valley , 3 km N Brahman, [GE est.] 130–150 m, 5° 40' S, 145° 22' E, 16 v 1991, D. Larson (5 MCZ) ; Morobe Province: Markham Valley, Gusap , 90 miles NW of Lae, ex small muddy pools in almost dry stream bed, much algae, 305 m, 5° 59' S, 146° 5' E, 27–30 i 1965, M. E. Bacchus (MEB 158) (1 NHM) ; Markham Valley, Gusap , 90 miles NW of Lae, small muddy pond, stony bottom, 305 m, 5° 59' S, 146° 5' E, 27–30 i 1965, M. E. Bacchus (MEB 158) (1 NHM) ; Markham Valley, Gusap , c. 90 mi. W of Lae, ex cattle water troughs, 305 m, 5° 59' S, 146° 5' E, 3 xii 1964, M. E. Bacchus (MEB 114) (1 NHM) ; Markham Valley, Gusap , c. 90 miles NW of Lae, large pond, muddy bottom with thick layer of dead leaves, dense Ceratophyllum , 305 m, 5° 59' S, 146° 5' E, 27–30 i 1965, M. E. Bacchus (MEB 162) (1 NHM) ; Markham Valley, Lae–Kainantu road, Erap River , ex gravel, [GE est.] 80–130 m, 6° 37' S, 146° 42' E, 26 i 1965, M. E. Bacchus (MEB 156) (1

NHM); Western (Fly) Province : Balimo, Om, [GE est.] 20–40 m, 8° 1.823' S, 142° 57.458' E, 9–11 xi 2008, Posman ( PNG 185) (21 MCZ, NHM, NMW, PNG, ZSM) .

Figures

FIGURE 178. Hydraena impercepta, holotype, dorsal and lateral habitus, and venter.

FIGURE 179. Hydraena cavifrons, holotype, dorsal and lateral habitus, and venter.

FIGURE 182. Hydraena buloba, holotype, dorsal and lateral habitus, and venter.

FIGURES 180–181. Aedeagi. 180. H. impercepta, non-type specimen from Moitaka, 7 mi. N. of Port Moresby. 181. H. cavifrons, holotype.

FIGURES 346–351. Scanning electron micrographs of H. impercepta (346–348), H. jubilata (349–350) and H. lassulipes (351).

FIGURES 408–411. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 515–518. Geographical distributions of Hydraena species.

FIGURES 184–185. Aedeagi of holotypes. 184. H. buloba. 185. H. impala.