Hydraena fasciata, Perkins, 2011

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 : 60-61

Hydraena fasciata , new species

( Figs. 90 , 92, 474 )

Type Material. Holotype (male): Morobe Province: Herzog Mts., Vagau [Wagau], ex gravel banks of swift shallow clear river, 1128 m, 6° 48' S, 146° 48' E, 8 i 1965, M. E. Bacchus (MEB 145a) ( NHM) . Paratypes (20): Morobe Province: Same data as holotype (11 NHM) ; Herzog Mts., Vagau [Wagau], ex muddy gravel banks of shallow clear swift river, 1220 m, 6° 48' S, 146° 48' E, 9 i 1965, M. E. Bacchus (MEB 147b) (7 NHM) ; Herzog Mts., Vagau [Wagau], Snake River , under gravel in bed of large slow river, 1220 m, 6° 48' S, 146° 48' E, 15 i 1965, M. E. Bacchus (MEB 152) (1 NHM) ; Markham Valley, Gusap , c. 90 mi. W of Lae, 305 m, 5° 59' S, 146° 5' E, 27– 30 i 1965, M. E. Bacchus (MEB 166) (1 NHM) .

Differential Diagnosis. Among members of the Colorata group, similar to H. paxillipes in having deep pronotal foveae PF2 and a very distinctive pronotal fascia ( Figs. 90 , 91 ); distinguished therefrom by the slightly larger size (ca. 1.55 vs. 1.47 mm), the more elongate pronotum (PL/PW ca. 0.86 vs. 0.77), and the slightly different plaque configurations. Males are additionally differentiated by the more markedly modified protibiae of H. fasciata , and the more distinctly arcuate metatibiae of H. paxillipes . The male genitalia of the two species markedly differ ( Figs. 92, 93).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.55/0.64; head 0.24/0.36; pronotum 0.38/0.44, PA 0.37, PB 0.37; elytra 0.97/0.64. Dorsum of head piceous; pronotum testaceous in front of and behind piceous fascia, ratios of color bands, as measured in midline, ca. 8/12/5; elytra brown, very slightly lighter around summit of posterior declivity; legs light brown to testaceous; maxillary palpi testaceous.

Frons punctures ca. 1xef; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely and very finely punctulate, strongly shining, each puncture with very fine, recumbent seta. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin straight; punctures on disc ca. 1xpd those of frons, interstices shining, 2–4xpd, punctures slightly larger and denser at anterior and posterior; PF1 united to form shallow transverse impression across anterior 1/3 of pronotal disc; PF2 deep, oval, oblique, shallowly confluent; PF3 moderately deep; PF4 shallow.

Elytra with summit of posterior declivity slightly before midlength; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/1/5/4. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward apex, apex joined to mesoventral midlongitudinal ridge. Plaques carinate, located at sides of deep, inverted V-shaped median depression. Metaventrite with midlongitudinal ridge between mesoventral intercoxal process and apex of median depression. AIS slightly concave, width at straight posterior margin ca. 1.5x P2. All legs long and slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia distinctively modified, median 1/3 of medial margin widened and bearing row of short stout spines, margin between apex and spines slightly emarginate. Mesotibia straight. Metatibia very slender, very slightly emarginate on medial surface. Abdominal apex symmetrical, or nearly so; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 92).

Etymology. Named in reference to the fasciate pronotum.

Distribution. Currently known from the Markham Valley at the border of Areas 3 and 5 (305 m), and the Herzog Mts., Area 6 (1220 m) ( Fig. 474 ).

Figures

FIGURE 90. Hydraena fasciata, holotype, dorsal and lateral habitus, and venter.

FIGURE 91. Hydraena paxillipes, holotype, dorsal and lateral habitus, and venter.

FIGURES 471–474. Geographical distributions of Hydraena species.