Hydraena pluralticola, 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 : 62-63

Hydraena pluralticola , new species

( Figs. 95 , 97, 399, 473 )

Type Material. Holotype (male): Morobe Province: c. 7 miles Lae–Bulolo road, ex gravel and grass roots on bank of small stream, [GE est.] 10–30 m, 6° 41' S, 146° 54' E, 30 xii 1964, M. E. Bacchus (MEB 120) ( NHM) . Paratypes (116): Madang Province: Sepik Ramu Basin, Kojé Creek , unshaded creek, small to medium cobbles, gravel and fine sand (the latter in areas of slack water), filamentous algae on stony substrates, small accumulations of leaf litter, 160 m, 5° 33' S, 145° 23' E, 1 vii–30 viii 1988, D. Dudgeon (88 NMW) ; Morobe Province: 3 miles

Bulolo–Lae road, ex mud banks of small stream, [GE est.] 50–150 m, 6° 42' S, 146° 57' E, 29 xii 1964, M. E. Bacchus (MEB 128) (2 NHM) ; Kassam Pass, Yung Creek , [GE est.] 1300–1500 m, 6° 12' S, 146° 0' E, 8 v 1979, W. G. Ullrich (4 MHNG) ; Lae–Bulolo road, ex dead leaves on mud bank, [GE est.] 900–1100 m, 6° 52' S, 146° 37' E, 28 xii 1964, M. E. Bacchus (MEB 123) (21 NHM) ; Western Highlands Province: Sepik River Basin, Kil Stream , montane forest, 1800 m, 5° 40' S, 144° 42' E, 16 viii 1988, D. Dudgeon (1 NMW) .

Differential Diagnosis. Distinguished from other members of the Colorata group by the pronotal macula, which grades to lighter color laterally but does not form a fascia; the color band ratios also differ from other species in the group, being ca. 4/4/3. Males have the protibiae and metatibiae modified somewhat similar to those of H. paxillipes , but the habitus and male genitalia of the two species differ markedly ( Figs. 91 , 93, 95 , 97).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.58; head 0.20/0.31; pronotum 0.33/0.41, PA 0.34, PB 0.34; elytra 0.80/0.58. Dorsum of head piceous; pronotum testaceous in front of and behind dark brown to piceous macula that gradually grades to light brown laterally, hence sub-fasciate, ratios of color bands, as measured in midline, ca. 8/8/6; elytra dark 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. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin very slightly emarginate; 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 shallow, oval, oblique, shallowly confluent; PF3 moderately deep; PF4 shallow or obsolete.

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, effacedly microreticulate, weakly shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect weakly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/1/4/4. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward apex. Plaques short, carinate, located at sides of deep, inverted V-shaped median depression. Metaventrite with very low midlongitudinal ridge between P2 and apex of median depression. AIS slightly concave, width at straight posterior margin ca. 1.5x P2. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia slightly arcuate, medial margin in distal 1/2 distinctively thickened and bearing row of very short, peg-like spines. Mesotibia straight. Metatibia moderately arcuate, medial margin in distal 1/4 with few recumbent hair-like setae. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 97). Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 399).

Etymology. Named in reference to the wide elevation range of the known collection localities.

Distribution. Currently known from the eastern parts of Areas 1–3; with a wide elevation range, 10–1800 m ( Fig. 473 ).

Figures

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

FIGURE 95. Hydraena pluralticola, holotype, dorsal and lateral habitus, and venter.

FIGURES 471–474. Geographical distributions of Hydraena species.