Hydraena variopaca, 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 : 94

Hydraena variopaca , new species

( Figs. 159 , 161 , 342 , 505 )

Type Material. Holotype (male): Eastern Highlands Province: Wanitabi Valley, nr. Okapa , on wet rocks above waterline in small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171c) ( NHM) . Paratypes (131): Eastern Highlands Province: Awande, Okapa , Eastern Highlands, [GE est.] 1500–1700 m, 6° 31' S, 145° 35' E, 25 v 1965, R. W. Hornabrook (3 NMNZ) ; Mjairasa, Okapa , ex stones in waterfall spray, [GE est.] 1500–1700 m, 6° 32' S, 145° 37' E, 17 iii 1965, R. W. Hornabrook (40 NMNZ) ; Okapa , ex muddy gravel banks of fast, clear stream, 1524 m, 6° 32' S, 145° 37' E, 9 ii 1965, M. E. Bacchus (MEB 183) (2 NHM) ; Okapa , on logs and vegetable debris in small river, 1524 m, 6° 32' S, 145° 37' E, 10 ii 1965, M. E. Bacchus (MEB 187a) (16 NHM) ; Okapa , on wet rocks above waterline, fast, clear stream, 1524 m, 6° 32' S, 145° 37' E, 9 ii 1965, M. E. Bacchus (MEB 183a) (13 NHM) ; Okapa , under stones in small river, 1524 m, 6° 32' S, 145° 37' E, 10 ii 1965, M. E. Bacchus (MEB 186) (12 NHM) ; same locality, 10 ii 1965, M. E. Bacchus (MEB 187) (26 NHM) ; Wanitabi Valley, nr. Okapa , on wet rocks above waterline in small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171c) (15 NHM) ; Gulf Province: Marawaka, near Ande , 1000 m, 7° 3.598' S, 145° 44.375' E, 10 xi 2006, Balke & Kinibel ( PNG 89) (1 ZSM) ; Madang Province: Finisterre Mts., Naho River Valley, nr. Moro , ex gravel banks of small fast stream, 1432 m, 5° 50' S, 146° 7' E, 7 xi 1964, M. E. Bacchus (MEB 91) (3 NHM) .

Differential Diagnosis. Among members of the Cristatigena group, quite similar in dorsal habitus to H. cristatigena ( Figs. 158 , 159 ); differing therefrom by the slightly larger size (ca. 1.88 vs. 1.81 mm), the slightly more widely spaced metaventral plaques, and the slightly coarser granulation of the elytra. Males are additionally recognized by the simple hind tibiae. The male genitalia of the two species differ in significant details, while in general shape suggest a rather close relationship ( Figs. 160, 160 ). The ventral surfaces of the head and prothorax are illustrated with an SEM ( Fig. 342 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.88/0.88; head 0.28/0.46; pronotum 0.43/0.58, PA 0.50, PB 0.48; elytra 1.17/0.88. Dorsum dark brown to piceous, head and pronotal disc slightly darker, palpi light brown, except distal 1/2 of last palpomere darker; legs brown, "knees" dark brown.

Dorsum of head and pronotum densely punctulate, dull; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1xpd or slightly larger; punctures of clypeus obsolete. Labrum apicomedially excised, free margins weakly upturned. Mentum sparsely punctate, effacedly microreticulate, weakly shining; postmentum anterior 1/2 with punctation similar to mentum, posterior 1/2 densely micropunctulate. Genae raised, posterior ridge strong. Pronotum with anterior margin weakly emarginate over middle 1/2; all pronotal foveae moderately deep.

Elytra subrugulose, dull, punctures very indistinct, most punctures with three granules, one at anterior margin and one on each side. Intervals not raised, width ca. 1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Explanate margin well developed, about as wide as widest part of metatibia.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 4/1/10/7. P1 laminate; median carina sinuate in profile. P2 moderately narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques very narrow, weakly raised, subcarinate, located at lateral margins of deep, median depression. Metaventrite tumid lateral to plaques. No midlongitudinal carina between mesoventral intercoxal process and plaques. Hydrofuge pubescence dense. AIS flat, width at straight posterior margin ca. 1.5x P2. Protibia (male) markedly widened, slightly arcuate, medial surface rather flat; mesotibia simple; metatibia slender, gradually increasing in width from base to apex, very weakly emarginate on medial surface slightly before midlength. Abdominal apex symmetrical.

Aedeagus ( Fig. 161 ) main piece with large distal lobe, in ventral aspect lobe apically pointed, with arcuate right side and left side with tiny lobe; left paramere small, not bilobed, setae in two clusters; right paramere sharply rounded apically; distal piece, in right lateral view, with knob-like lobe.

Etymology. Named in reference to the varyingly dull dorsum.

Distribution. Currently known from far eastern Area 1 (1000–1700 m) and one locality in the Finisterre Mts., Area 5 (1432 m) ( Fig. 505 ). This is one of ten species with distributions exclusively shared between Areas 1 and 5 ( Fig. 422 ).

Figures

FIGURE 158. Hydraena cristatigena, holotype, dorsal and lateral habitus, and venter.

FIGURE 159. Hydraena variopaca, holotype, dorsal and lateral habitus, and venter.

FIGURES 160–161. Aedeagi. 160. H. cristatigena, non-type specimen from E. Highlands, Wanatabe Valley, nr. Okapa. 161. H. variopaca, holotype.

FIGURES 340–345. Scanning electron micrographs of H. bacchusi (340–341), H. variopaca (342) and H. cristatigena (343– 345).

FIGURES 503–506. Geographical distributions of Hydraena species.

FIGURES 421–422. 421. All known collecting localities for Papua New Guinea Hydraena. 422. Ten species, representing eight species groups, with distributions exclusively shared between Areas of Endemism 1 and 5.