Hydraena nanocolorata, 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 : 63-64

Hydraena nanocolorata , new species

( Figs. 98 , 100 , 475 )

Type Material. Holotype (male): 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 ( NMW) . Paratypes (101): Madang Province: Same data as holotype (84 NMW) ; Morobe Province: Markham Valley, Gusap , 90 miles NW of Lae, ex dead leaves on mud wetted by seepage, 305 m, 5° 59' S, 146° 5' E, 27–30 i 1965, M. E. Bacchus (MEB 163) (17 NHM) .

Differential Diagnosis. Among members of the Colorata group similar to H. colorata in having shallow pronotal foveae PF2 and a distinctive pronotal fascia ( Figs. 87 , 98 ); distinguished therefrom by the smaller size (ca. 1.15 vs. 1.25 mm), the differently shaped pronotum (PA slightly greater than PB), the proportionally shorter elytra, and the slightly sparser dorsal punctation. The pronotal fasciae also differ in the two species, the color band ratios being ca. 6/9/ 4 in H. nanocolorata and ca. 7/10/ 5 in H. colorata . The male genitalia of the two species distinctively differ ( Figs. 89 , 100 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.15/0.52; head 0.17/0.29; pronotum 0.30/0.39, PA 0.33, PB 0.32; elytra 0.69/0.52. Dorsum of head piceous; pronotum testaceous to light brown in front of and behind piceous fascia, ratios of color bands, as measured in midline, ca. 6/9/4; elytra brown; legs light brown to testaceous; maxillary palpi testaceous.

Frons punctures ca. 1xef; interstices shining, 2–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely and very finely punctulate, strongly shining. Genae very slightly raised, shining, without posterior ridge. Pronotum cordiform, anterior margin 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.

Elytra weakly convex, posterior declivity gradual, 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. 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 very slightly raised, l/w ca. 2/1, sides slightly converging toward apex. Plaques short, carinate, located at sides of deep, inverted U-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, 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 straight, medial margin in distal 1/4 with few recumbent hair-like setae. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 100 ).

Etymology. Named in reference to the small size and relationship with H. colorata .

Distribution. Currently known from two localities in eastern Area 3; elevations 160 m and 305 m ( Fig. 475 ).

Figures

FIGURE 87. Hydraena colorata, holotype, dorsal and lateral habitus, and venter.

FIGURE 98. Hydraena nanocolorata, holotype, dorsal and lateral habitus, and venter.

FIGURES 100–101. Aedeagi of holotypes. 100. H. nanocolorata. 101. H. clarinis.

FIGURES 475–478. Geographical distributions of Hydraena species.

FIGURES 88–89. Aedeagi of holotypes. 88. H. koma. 89. H. colorata.