Hydraena dudgeoni, 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 : 119-120

Hydraena dudgeoni , new species

( Figs. 218 , 220 , 528 )

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: Same data as holotype (6 NMW) .

Differential Diagnosis. A broad, banded species, somewhat similar to H. fasciolata in habitus ( Figs. 218 , 219 ); differing therefrom by the smaller size (ca. 1.38 vs. 1.44 mm), the less distinctly color-banded elytra, and the less widely spaced procoxae (plaque ratios ca. 7/1/6/8 vs. 9/1/6/8). The male genitalia of the two species differ markedly ( Figs. 220, 221 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.38/0.66; head 0.18/0.34; pronotum 0.36/0.53, PA 0.39, PB 0.45; elytra 0.86/0.66. Dorsum distinctively banded: labrum and clypeus light brown to testaceous; frons dark brown; pronotum testaceous; elytra dark brown in anterior ca. 7/15, with testaceous fascia at posterior declivity, and similarly colored band across elytral apices, the two testaceous areas separated by light brown crescent shaped band; legs and maxillary palpi testaceous, tip of palpus not darker.

Frons punctures ca. 1xef, slightly larger near eyes than medially; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum subcordiform, ca. median 3/4 of anterior margin arcuate to posterior; punctures on disc ca. 1xpd frons punctures, interstices shining, 1–3xpd, punctures not appreciably larger at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 shallow; PF4 absent.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins rather wide in anterior 1/2 where sides of elytra gradually sloping; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2–5xpd, 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. 7/1/6/8. P1 ca. 5/7 P2; median carina straight in profile; postcoxal process medially concave. P2 transversely concave, l/w ca. 5/7, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, converging slightly anteriorly, at sides of very deep median depression. Metaventrite concave between P2 and plaques. AIS width at straight posterior margin ca. equal P2. All legs moderately long and slender. Profemur (male) with very small tubercle next to trochanter; protibia arcuate, gradually increasing in width from base to apex. Mesotibia very slightly arcuate. Metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 220 ).

Etymology. Named in honor of aquatic ecologist David Dudgeon, collector of this and other new species of PNG Hydraena .

Distribution. Currently known only from the type locality, Kojé Creek, in the eastern arm of Area 3; elevation 160 m ( Fig. 528 ).

Figures

FIGURE 218. Hydraena dudgeoni, holotype, dorsal and lateral habitus, and venter.

FIGURE 219. Hydraena fasciolata, holotype, dorsal and lateral habitus, and venter.

FIGURES 220–221. Aedeagi of holotypes. 220. H. dudgeoni. 221. H. fasciolata.

FIGURES 527–530. Geographical distributions of Hydraena species.