Hydraena receptiva, 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 : 133-134

Hydraena receptiva , new species

( Figs. 246 , 248, 376–379 , 544 )

Type Material. Holotype (male): Morobe Province: 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) ( NHM) . Paratypes (56): East Sepik Province: Sepik, main river, [GE est.] 5–20 m, 4° 12' S, 143° 36' E, 2 iii 1965, R. W. Hornabrook (7 NMNZ) ; Yentchan , main Sepik River , in small stream behind village, [GE est.] 20–50 m, 4° 8' S, 142° 55' E, 18 iii 1965, R. W. Hornabrook (1 NMNZ) ; Madang Province: 5 km N Kawe , plantation drain, [GE est.] 10–60 m, 4° 58' S, 145° 47' E, 11 iii 1991, D. Larson (4 MCZ) ; 5 km NW CRI, Nagada Harb , [GE est.] 10–30 m, 5° 20' S, 145° 42' E, 18 iii 1991, D. Larson (1 MCZ) ; 7 km W Bagildik, Murnass River , [GE est.] 400–600 m, 4° 57' S, 145° 43' E, 8 iii 1991, D. Larson (5 MCZ) ; Gogal Valley , 4 km S Baru Village, [GE est.] 300–500 m, 5° 42' S, 146° 32' E, 10 iv 1991, D. Larson (2 MCZ) ; Gogal Valley, Baru Village , [GE est.] 300–500 m, 5° 40' S, 146° 32' E, 10 iv 1991, D. Larson (7 MCZ) ; Gogal Valley nr. Kokun River , [GE est.] 40–80 m, 5° 17' S, 145° 38' E, 3 v 1991, D. Larson (6 MCZ) ; Nagada River nr. Nobanob , [GE est.] 10–40 m, 5° 10' S, 145° 45' E, 12 vi 1991, D. Larson (10 MCZ) ; Ramu Valley , 6 km N Brahman, [GE est.] 130–150 m, 5° 38' S, 145° 22' E, 21 vi 1991, D. Larson (5 MCZ) ; Morobe Province: 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) (8 NHM) .

Differential Diagnosis. Differentiated from other members of the Fundextra group by the shape of the pronotum, which is subtrapezoidal, having the sides straight between the widest part and the posterior angle ( Fig. 246 ); in other members of the group the sides are sinuate in this area. The carinate metaventral plaques are unusual in that they are higher anteriorly than posteriorly. The male genitalia distinctively differ from those of other members of the group ( Fig. 248). The prosternum, meso- and metaventrite, and the abdominal apex of female are illustrated with SEMs ( Figs. 376–379 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.36/0.64; head 0.19/0.34; pronotum 0.36/0.50, PA 0.37, PB 0.51; elytra 0.81/0.64.

Dorsum of head dark brown to piceous; pronotum brown around dark brown to piceous, diffusely margined, macula, ratios of color bands, as measured in midline, ca. 7/13/4; elytra dark brown; legs light brown; maxillary palpi testaceous, tip not darker. Dorsum weakly shining.

Frons punctures ca. 1xef, not notably smaller or sparser medially; interstices effacedly microreticulate, dull, 1– 2xpd. Clypeus effacedly microreticulate, very finely sparsely punctulate medially. Mentum very sparsely very finely punctulate, shining. Postmentum effacedly microreticulate in shallow median depression, otherwise finely sparsely punctate. Genae very slightly raised, shining, with shallow, obsolete median impression, without posterior ridge. Pronotum transverse, ca. median 3/4 of anterior margin slightly arcuate to posterior, sides weakly arcuate, not emarginate between midlength and posterior angle; punctures on disc ca. 1xpd of largest frons punctures, interstices strongly shining, ca. 2–6xpd, punctures posteriorly slightly larger than those on disc; PF1 and PF4 absent; PF2 very shallow, completely shallowly confluent in midline to form U-shaped, exceedingly shallow impression; PF3 moderately deep, wide.

Elytra with posterior declivity very gradual, summit at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect slightly separately rounded, in posterior aspect margins forming angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 5/1/8/7. P1 very slightly wider than laminate; median carina nearly straight in profile, very slightly arcuate between coxae. P2 markedly concave, length/width ca. 6/5, sides very slightly diverging toward blunt apex. Plaques carinate lines, slightly higher anteriorly than posteriorly, parallel, at sides of densely punctate median depression. Metaventrite between mesocoxae slightly sloping, confluent with tip of P2. AIS width at straight posterior margin slightly greater than P2. All legs of moderate length. Profemur (male) with minute tubercle on ventral margin near basal 1/3; protibia arcuate in proximal 1/2, distal 1/2 slightly widened. Meso- and metatibia straight, slender. Abdominal apex asymmetrical; last tergite (male) with deep concavity near apex, offset to left side. Aedeagus as illustrated ( Fig. 248).

Etymology. "The receiving one"; named in reference to the depression between the mesocoxae, which receives the apex of the prosternal intercoxal process.

Distribution. Currently known from both western and eastern arms of Area 3, and from several lowland localities in Area 5; elevation range 5–1100 m, but only one locality above 150 m ( Fig. 544 ).

Figures

FIGURE 246. Hydraena receptiva, holotype, dorsal and lateral habitus, and venter.

FIGURES 376–381. Scanning electron micrographs of H. receptiva (376–379) and H. thola (380–381).

FIGURES 543–546. Geographical distributions of Hydraena species.