Hydraena otiarca, 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 : 43-45

Hydraena otiarca , new species

( Figs. 55 , 57 , 302, 303 , 362, 363 , 394, 456 )

Type Material. Holotype (male): Morobe Province: Herzog Mts., Vagau [Wagau], Snake River , under gravel in bed of large slow river, 1220 m, 6° 48' S, 146° 48' E, 15 i 1965, M. E. Bacchus (MEB 152) ( NHM) . Paratypes (189): Madang Province: Adelbert Mts. , below Keki, 790 m, 4° 42.3' S, 145° 25.089' E, 5 v 2006, Balke & Manaono ( PNG 53) (10 MCZ, NHM, NMW, PNG, ZSM) ; Finisterre Mts. , Lower Naho Valley, Hinggia, ex rocks and gravel bank of swift clear stream, 762 m, 5° 50' S, 146° 7' E, 28 xi 1964, M. E. Bacchus (MEB 112) (25 NHM) ; Finisterre Mts. , Naho River Valley, Budemu, ex gravel banks of large river, 1264 m, 5° 56' S, 146° 40' E, 18 x 1964, M. E. Bacchus (MEB 61) (5 NHM) ; Finisterre Mts. , Naho River Valley, Budemu, ex sand and gravel banks of small stream, but only in the 20 yards that it is permanent, 1264 m, 5° 56' S, 146° 40' E, 19 x 1964, M. E. Bacchus (MEB 62) (11 NHM) ; Finisterre Mts. , Naho River Valley, Damanti, ex gravel bank of shallow stream, 1082 m, 5° 55' S, 145° 58' E, 12 x 1964, M. E. Bacchus (MEB 49) (3 NHM) ; Finisterre Mts. , Naho River Valley, Damanti, ex gravel banks of small fast river, 1082 m, 5° 55' S, 145° 58' E, 8 x 1964, M. E. Bacchus (MEB 37) (2 NHM) ; Finisterre Mts. , Naho River Valley, Damanti, ex gravel banks of very fast-running clear stream, 914 m, 5° 55' S, 145° 58' E, 11 x 1964, M. E. Bacchus (MEB 47) (5 NHM) ; Finisterre Mts. , Naho River Valley, Damanti, ex small pool, probably permanent, in clay in dense shade, 1067 m, 5° 55' S, 145° 58' E, 8 x 1964, M. E. Bacchus (MEB 39) (6 NHM) ; Finisterre Mts. , Naho River Valley, nr. Moro, ex dead leaves and muddy gravel by small stream, 1372 m, 5° 50' S, 146° 7' E, 5 xi 1964, M. E. Bacchus (MEB 88) (4 NHM) ; Finisterre Mts. , Naho River Valley, nr. Sewe, large flat area of wet gravel with small rivulets running through it, 1615 m, 5° 51' S, 146° 8' E, 15 xi 1964, M. E. Bacchus (MEB 95) (5 NHM) ; Morobe Province: Herzog Mts. , Vagau [Wagau], ex dead leaves in small stream in dense forest, 1220 m, 6° 48' S, 146° 48' E, 6 i 1965, M. E. Bacchus (MEB 139) (4 NHM) ; Herzog Mts. , Vagau [Wagau], ex gravel banks of small clear river in dense forest, 1220 m, 6° 48' S, 146° 48' E, 6 i 1965, M. E. Bacchus (MEB 140a) (32 NHM) ; Herzog Mts. , Vagau [Wagau], ex leaves caught among rocks in shallow clear swift river, 1220 m, 6° 48' S, 146° 48' E, 9 i 1965, M. E. Bacchus (MEB 147a) (1 NHM) ; Herzog Mts. , Vagau [Wagau], ex muddy gravel banks of shallow clear swift river, 1220 m, 6° 48' S, 146° 48' E, 9 i 1965, M. E. Bacchus (MEB 147b) (70 NHM) ; Huon Pen. , Kwapsanek, 850 m, 6° 34.913' S, 147°.526' E, 31 iii 2006, Balke & Sagata ( PNG 25) (6 MCZ, NHM, NMW, PNG, ZSM) .

Differential Diagnosis. Similar in dorsal habitus to H. cheesmanae ( Figs. 55 , 59 ); differing therefrom in being slightly larger (ca. 1.46 vs. 1.37), in having a more coarsely punctate pronotum with PA slightly wider than PB (PA and PB equal in H. cheesmanae ), and having the metaventral plaques slightly longer and closer together (ratios ca. 3/2/9/2 vs. 3/3/8/3). The male metatibiae differ very slightly in the two species, whereas the male genitalia differ distinctively in many details ( Figs. 57 , 61 ). The metaventrite, abdominal apex, and very complicated chaetotaxy of the tibiae are illustrated with SEMs ( Figs. 302, 303 , 362, 363 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.46/0.63; head 0.24/0.35; pronotum 0.36/0.44, PA 0.38, PB 0.40; elytra 0.87/0.63. Dorsum of head piceous; pronotum testaceous in front of and behind piceous fascia, ratios of color bands, as measured in midline, ca. 5/15/4; elytra dark brown; legs brown; maxillary palpi light brown to testaceous, tip not darker.

Frons punctures ca. 1xef; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and anterior 1/2 of postmentum very sparsely very finely punctulate, shining; posterior 1/2 of postmentum effacedly micropunctulate. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; punctures on disc slightly larger and deeper than those of frons, interstices shining, 1–4xpd, punctures slightly larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 deep; PF4 absent.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–2xpd, 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. 3/2/9/2. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward blunt apex. Plaques large, diverging slightly from posterior to anterior, weakly transversely raised, at sides of deep median depression, each plaque tapering slightly from posterior to anterior. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin slightly greater than P2. All legs long and slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia very slightly arcuate, widest subapically, cluster of small spines on medial margin at this point. Mesotibia straight. Metatibia straight or near so, medial margin in distal 1/2 weakly emarginate and with few long setae that lie flat on cuticle in dry specimens. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 57 ). Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 394).

Etymology. "Resting bow"; named in reference to the extremely weakly arcuate male metatibiae, and to the relatively small aedeagus.

Distribution. Currently known from several localities in Area 5, and one locality (Herzog Mts.) in Area 6; elevation range 760–1615 m ( Fig. 456 ).

Figures

FIGURE 55. Hydraena otiarca, holotype, dorsal and lateral habitus, and venter.

FIGURE 59. Hydraena cheesmanae, holotype, dorsal and lateral habitus, and venter.

FIGURES 56–57. Aedeagi of holotypes. 56. H. infoveola. 57. H. otiarca.

FIGURES 298–303. Scanning electron micrographs of H. remulipes (298–301) and H. otiarca (302–303).

FIGURES 358–363. Scanning electron micrographs of H. quintana (358–361) and H. otiarca (362–363).

FIGURES 455–458. Geographical distributions of Hydraena species.

FIGURES 60–61. Aedeagi of holotypes. 60. H. remulipes. 61. H. cheesmanae.