Hydraena ambroides, 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 : 22-23

Hydraena ambroides , new species

( Figs. 14 , 16 , 432 )

Type Material. Holotype (male): Eastern Highlands Province: Wanitabi Valley, nr. Okapa , gravel banks of small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171a) ( NHM) . Paratypes (180): Eastern Highlands Province: 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) (15 NHM) ; Purosa Valley, nr. Okapa , on submerged stones, [GE est.] 1500– 1700 m, 6° 32' S, 145° 37' E, 8 ii 1965, M. E. Bacchus (MEB 182a) (1 NHM) ; Umg. [=environs of] Igipinti, Korindaiop River , [GE est.] 600–1700 m, 6° 25' S, 145° 42' E, 18 vi 1979, W. G. Ullrich (18 MHNG) ; Umg. [=environs of] Kainantu, Onerunka , [GE est.] 1500–1700 m, 6° 17' S, 145° 52' E, 24 ii 1980, W. G. Ullrich (3 MHNG) ; Umg. [=environs of] Okapa , [GE est.] 1500–1700 m, 6° 32' S, 145° 37' E, 18 vi 1979, W. G. Ullrich (6 MHNG) ; Umg. [=environs of] Onerunka, Ramu River , [GE est.] 1500–1700 m, 6° 20' S, 145° 47' E, 9 xii 1979, W. G. Ullrich (6 MHNG) ; Wanitabi Valley, nr. Okapa , ex dead leaves caught among rocks in small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171b) (38 NHM) ; Wanitabi Valley, nr. Okapa , ex muddy gravel banks of small shaded stream, 1524 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 177a) (7 NHM) ; Wanitabi Valley, nr. Okapa , gravel banks of small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171a) (1 NHM) ; Wanitabi Valley, nr. Okapa , on partly rotted floating logs, 1524 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 176a) (41 NHM) ; Wapi Creek, Kimiagomo, Okapa , ex debris and submerged logs in creek, 1900 m, 6° 25' S, 145° 34' E, 9 viii 2005, K. Sagata (WB 123) (3 ZSM) ; Gulf Province: Marawaka, near Ande , 1000 m, 7° 3.598' S, 145° 44.375' E, 10 xi 2006, Balke & Kinibel ( PNG 89) (3 ZSM) ; Madang Province: Finisterre Mts., Naho River Valley, Budemu –Kikipei track, ex gravel bank of small river in places where rotten leaves had accumulated, 1220 m, 5° 56' S, 146° 40' E, 24 x 1964, M. E. Bacchus (MEB 73) (4 NHM) ; Morobe Province: 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) ; Western Highlands Province: Sepik River Basin, Kil Stream , montane forest, 1800 m, 5° 40' S, 144° 42' E, 1 vii–30 viii 1988, D. Dudgeon (11 NMW) ; same locality, 16 viii 1988, D. Dudgeon (22 NMW) .

Differential Diagnosis. Quite similar in dorsal habitus to H. ambra and H. ambripes ( Figs. 10 , 11 , 14 ); differing from H. ambra by the unicolored head, the more strongly punctate dorsum, and the smaller size (ca. 1.71 vs. 1.82 mm); differing from H. ambripes by the confluent pronotal foveae PF2, the differently shaped pronotum, and the longer elytra. Males of H. ambroides are distinguished from males of H. ambra by the non-modified mesotibiae, and from those of H. ambripes by the non-modified protibia. The male genitalia of the three species ( Figs. 12, 13 , 16 ) clearly show a relationship; among other differences, the aedeagus of H. ambroides can be recognized by the very differently shaped right paramere.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.71/0.73; head 0.25/0.38; pronotum 0.40/0.48, PA 0.40, PB 0.41; elytra 1.07/0.73. Dorsum varying from amber colored with dark brown head and pronotal fascia to entirely dark brown with piceous head and pronotal disc, head not bicolored, legs light brown in amber individuals, brown in darker individuals, maxillary palpi brown to testaceous.

Frons punctures ca. 1xef; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate and shining medially. Mentum very sparsely very finely punctate, shining; postmentum very finely densely micropunctulate in median concavity, surrounding areas smooth, shining. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin emarginate; lateral margins turning outward slightly at posterior angles; punctures on disc ca. 1–2xpd those of frons, interstices shining, 1–4xpd, punctures much larger and much denser at anterior and posterior; PF1 united to form shallow transverse impression across anterior 1/3 of pronotal disc; PF2 deep, oval, oblique, very shallowly confluent in middle, conjointly forming U-shaped impression; PF3 and PF4 moderately deep.

Elytra distinctively humped just behind midlength, at summit of posterior declivity; lateral margins evenly arcuate; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few random, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect very 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. 4/1/7/5. P1 narrow, not laminate; median carina sinuate in profile. P2 raised, l/w ca. as 3/2, sides slightly converging toward apex, apex joined to raised mesoventral intercoxal process. Plaques narrow, slightly arcuate, converging toward one another anteriorly, weakly raised, weakly carinate laterally, located at sides of deep, median depression. Metaventrite with short midlongitudinal ridge between mesoventral intercoxal process and median depression, also with longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS and adjacent area on first ventrite conjointly forming shallow concavity; AIS width at straight posterior margin ca. 1.5x P2. Profemur (male) with small, sharply pointed tubercle next to trochanter; all tibiae slender, straight. Abdominal apex symmetrical.

Etymology. Named in reference to relationship to H. ambra .

Distribution. Currently known from Areas 1 (eastern), 5, and 6; elevation range 1000–1900 m ( Fig. 432 ).

Figures

FIGURE 10. Hydraena ambra, holotype, dorsal and lateral habitus, and venter.

FIGURE 11. Hydraena ambripes, holotype, dorsal and lateral habitus, and venter.

FIGURE 14. Hydraena ambroides, holotype, dorsal and lateral habitus, and venter.

FIGURES 16–17. Aedeagi of holotypes. 16. H. ambroides. 17. H. sagatai.

FIGURES 431–434. Geographical distributions of Hydraena species.

FIGURES 12–13. Aedeagi of holotypes. 12. H. ambra. 13. H. ambripes.