Hydraena trichotarsa, 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 : 34-35

Hydraena trichotarsa , new species

( Figs. 38 , 40, 446 )

Type Material. Holotype (male): Morobe Province: Lae–Bulolo road, ex stones and gravel bank of large river, 6° 52' S, 146° 37' E, 28 xii 1964, M. E. Bacchus (MEB 124) ( NHM) . Paratypes (22): Oro Province: Northern District, tributary Musa , in open river bed backwater, 100–300 m, 9° 20' S, 148° 55' E, 21 viii 1975, R. W. Hornabrook (22 NMNZ) .

Differential Diagnosis. Among members of the Manulea group, somewhat similar in body shape to H. mianminica ( Figs. 38 , 39 ); differing therefrom by the slightly wider elytra, the narrower pronotal fascia (color bands ca. 7/13/7 vs. 6/16/4), the coarser elytral punctation, and the slightly differently shaped metaventral plaques (ratios ca. 2/3/8/3 vs. 3/2/8/3). Males of H. trichotarsa have long brushes of setae on the meso- and metatarsi. The male genitalia of the two species distinctively differ ( Figs. 40, 41).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.64/0.67; head 0.22/0.39; pronotum 0.41/0.50, PA 0.42, PB 0.43; elytra 0.95/0.67. Holotype teneral; mature specimen with dorsum of head piceous; pronotum brown in front of and behind dark brown fascia, ratios of color bands, as measured in midline, ca. 7/13/7; elytra brown to dark brown; legs brown; maxillary palpi light brown, tip of palpus 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 cordiform, median 1/2 of anterior margin very slightly emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 2–4xpd, punctures larger and denser at anterior and posterior; PF1 very shallow; PF2 shallow; PF3 deep; PF4 very shallow or absent.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins rather wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–3xpd, as are interstices between punctures of a row, a few punctures subserial. 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. 2/3/8/3. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 3/1, sides converging toward blunt apex. Plaques moderately wide, parallel, weakly raised, located at sides of deep, median depression, each plaque tapering slightly from posterior to anterior. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 2x P2. All legs moderately long and slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia arcuate, distal 1/3 slightly widened on anterior surface and slightly widened on medial margin, medial margin apically with cluster of very short spines. Meso- and metatibia moderately arcuate. Meso- and metatarsi with long hair-like setae beneath. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated ( Fig. 40).

Etymology. Named in reference to the prominent setae of the meso- and metatarsi, and to the relationship to H. tarsotricha .

Distribution. Currently known only from two localities, one at the border of Areas 3 and 6 (Lae–Bulolo road) at 900–1100 m, and one at the border of Areas 8 and 9, at 100–300 m ( Fig. 446 ).

Note. The holotype ( Fig. 38 ) is teneral; mature specimens are much darker.

Figures

FIGURE 38. Hydraena trichotarsa, holotype, dorsal and lateral habitus, and venter.

FIGURE 39. Hydraena mianminica, holotype, dorsal and lateral habitus, and venter.

FIGURES 443–446. Geographical distributions of Hydraena species.