Hydraena lassulipes, 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 : 38-39

Hydraena lassulipes , new species

( Figs. 46 , 48, 351 , 392, 454 )

Type Material. Holotype (male): Morobe Province: Herzog Mts., Vagau [Wagau], ex gravel banks of small clear river in dense forest, 1220 m, 6° 48' S, 146° 48' E, 6 i 1965, M. E. Bacchus (MEB 140a) ( NHM) . Paratypes (150): Eastern Highlands Province: Okapa , small algae filled puddle, 1524 m, 6° 32' S, 145° 37' E, 10 ii 1965, M. E. Bacchus (MEB 188) (4 NHM) ; Purosa Valley, nr. Okapa , on submerged stones, [GE est.] 1500–1700 m, 6° 32' S, 145° 37' E, 8 ii 1965, M. E. Bacchus (MEB 182a) (1 NHM) ; Umg. [=environs of] Okapa , [GE est.] 1500– 1700 m, 6° 32' S, 145° 37' E, 18 vi 1979, W. G. Ullrich (3 MHNG) ; Wanitabi Valley, nr. Okapa , ex dead leaves caught among rocks in small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171b) (4 NHM) ; Wanitabi Valley, nr. Okapa , gravel banks of small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171a) (2 NHM) ; Gulf Province: Marawaka, Mala , 1400 m, 7° 5.664' S, 145° 44.467' E, 11 xi 2006, Balke & Kinibel ( PNG 90) (11 MCZ, NHM, NMW, PNG, ZSM) ; Marawaka, near Ande , 1000 m, 7° 3.598' S, 145° 44.375' E, 10 xi 2006, Balke & Kinibel ( PNG 89) (1 ZSM) ; Morobe Province: Same data as holotype (117 NHM) ; Herzog Mts., Vagau [Wagau], ex leaves caught among rocks in shallow clear swift river, 1220 m, 6° 48' S, 146° 48' E, 9 i 1965, M. E. Bacchus (MEB 147a) (1 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) (6 NHM) .

Differential Diagnosis. The dorsal habitus is somewhat similar to that of H. supina ( Figs. 46 , 47 ); differing therefrom by the shape of the pronotum, with PA and PB being equal, and the sides not distinctively emarginate between the anterior angles and the widest part; differing additionally by the smaller size (ca. 1.77 vs. 1.90 mm). The metaventral plaques and the slightly arcuate male metatibiae are quite similar to those of H. supina and H. nitidimenta . The aedeagus ( Fig. 48) distinctively differs from that of other members of the Jubilata group, and should be examined for reliable determinations. The complicated chaetotaxy of the metatibia is illustrated with an SEM ( Fig. 351 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.77/0.71; head 0.29/0.36; pronotum 0.39/0.47, PA 0.42, PB 0.42; elytra 1.09/0.71. Dorsum dark brown to piceous, anterior margin of pronotum slightly lighter, legs and maxillary palpi brown.

Frons punctures ca. 1xef; interstices shining, 1–4xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum finely sparsely punctate. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 1–5xpd, punctures slightly larger and denser at anterior and posterior; PF1 united to form shallow transverse impression across anterior 1/3 of pronotal disc; PF2 shallow, oval, oblique, not confluent; PF3 moderately deep; PF4 obsolete.

Elytra with summit of posterior declivity slightly past 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. 2/1/4/2. 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 moderately wide, parallel, weakly raised, located at sides of deep, median depression. Metaventrite with short midlongitudinal ridge between mesoventral intercoxal process and median depression. AIS width at straight posterior margin very slightly greater than P2. All legs long and very slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia weakly arcuate. Mesotibia straight. Metatibia moderately arcuate. Abdominal apex symmetrical; last tergite (male) deeply notched.

Aedeagus ( Fig. 48) main piece, in ventral aspect, with right side characteristically thick-walled and angulate; both parameres, in lateral aspects, wide in distal 1/2; left paramere only slightly longer than right; right paramere with cluster of setae at apical angle. Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 392).

Etymology. "Little weary foot"; named in reference to the very slender legs and relatively heavy body.

Distribution. Currently known from eastern Area 1 and from Area 6 (Herzog Mts.); elevation range 1000– 1700 m ( Fig. 454 ).

Figures

FIGURE 46. Hydraena lassulipes, holotype, dorsal and lateral habitus, and venter.

FIGURE 47. Hydraena supina, holotype, dorsal and lateral habitus, and venter.

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

FIGURES 451–454. Geographical distributions of Hydraena species.