Hydraena funda, 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 : 146-147

Hydraena funda , new species

( Figs. 271 , 273 , 370–372 , 560 )

Type Material. Holotype (male): Central Province: Moitaka , 7 miles N of Port Moresby, ex dead leaves in gravelly shallow of small pond, [GE est.] 30–50 m, 9° 25' S, 147° 12' E, 17 iii 1965, M. E. Bacchus (MEB 207) ( NHM) . Paratypes (10): Central Province: Same data as holotype (4 NHM) ; Port Moresby – Brown River road, ex grassy shallows of large muddy pond, [GE est.] 50–100 m, 9° 24' S, 147° 14' E, 15 iii 1965, M. E. Bacchus (MEB 195) (6 NHM) .

Differential Diagnosis. Differentiated from other PNG members of the genus by the combination of very small size (ca. 1.16 mm), trapezoidal pronotum, and extremely finely punctate dorsum ( Fig. 271 ). The male genitalia distinctly differ from those of other PNG Hydraena , but are quite similar to the genitalia of the Australian species H. trapezoidalis ( Fig. 273 ). The prosternum, meso- and metaventrite, abdominal apex of female, and complicated chaetotaxy of the protibiae are illustrated with SEMs ( Figs. 370–372 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.16/0.51; head 0.18/0.30; pronotum 0.29/0.44, PA 0.33, PB 0.44; elytra 0.69/0.51. Dorsum of head dark brown to dark reddish brown; pronotum light brown to testaceous around dark brown, rectangular macula on disc, ratios of color bands, as measured in midline, ca. 5/10/4; elytra dark brown, with interstices lighter than columellae; legs light brown to testaceous; maxillary palpi testaceous, tip not darker. Dorsum very shiny.

Frons punctures ca. 1xef, larger and denser near eyes than medially; interstices shining, 1–2xpd laterally, ca. 4– 8xpd medially. Clypeus effacedly microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining. Postmentum anteriorly finely punctate, posteriorly moderately coarsely punctate, shining. Genae flat or very slightly raised, shining, without posterior ridge. Pronotum trapezoidal, ca. median 3/4 of anterior margin slightly arcuate to posterior; punctures on disc extremely fine and sparse, usually smaller than smallest frons punctures, interstices strongly shining, ca. 5–10xpd or more; PF1, PF2 and PF4 absent; PF3 moderately deep, obsolete, large.

Elytra with summit of weak posterior declivity slightly posterior to midlength; lateral explanate margins narrow. Punctures very small, shallow, and widely spaced, for the most part not forming discrete series. Intervals strongly shining. 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. 2/2/3/6. P1 ca. 1/2 P2; median carina nearly straight in profile, very slightly arcuate between coxae. P2 transversely slightly concave, length ca. 2x width, sides slightly converging toward blunt, non-raised apex. Plaques roundly slightly raised, converging anteriorly, at sides of inverted V-shaped median depression. Metaventrite not concave between P2 and plaques. AIS width at straight posterior margin ca. 2x P2. All legs of moderate length, tibiae very slender. Profemur (male) without tubercle next to trochanter; protibia very slightly arcuate, gradually increasing in width from base to apex. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) sharply rounded. Aedeagus as illustrated ( Fig. 273 ).

Etymology. "Base, bottom"; named in reference to the wide pronotal base.

Distribution. Currently known from two very narrowly separated localities near Port Moresby (Area 11), elevation ca. 30–100 m ( Fig. 560 ). This is the putative sister species of H. trapezoidalis , which is distributed in northern Australia ( Fig. 559 ).

Figures

FIGURE 271. Hydraena funda, holotype, dorsal and lateral habitus, and venter.

FIGURES 272–273. Aedeagi of holotypes. 272. H. pegopyga. 273. H. funda.

FIGURES 370–375. Scanning electron micrographs of H. funda (370–372) and H. incisiva (373–375).

FIGURES 559–562. Geographical distributions of Hydraena species.