Hydraena tarsotricha, 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 : 50-51

Hydraena tarsotricha , new species

( Figs. 67 , 69, 308–309 , 314–315 , 396, 459 )

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 (26): Madang Province: Finisterre Mts., Naho River Valley, nr. Moro , walking on surface of dead leaves. Specimens pure white color when alive, 2134 m, 5° 50' S, 146° 7' E, 10 xi 1964, M. E. Bacchus (MEB 94) (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) (17 NHM) ; Morobe Province: 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) (2 NHM) ; 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) (2 NHM) ; Western Highlands Province: Simbai , 1800–2000 m, 5° 14.276' S, 144° 28.741' E, 1 iii 2007, Kinibel ( PNG 138) (1 ZSM) .

Differential Diagnosis. Similar in habitus and some male sexual dimorphisms (no tubercle on first abdominal ventrite, fifth ventrite with transverse ridge, long hair-like setae on the meso- and metatarsi) to H. tricosipes ( Figs. 67 , 70 ); differing therefrom by the larger size (ca. 1.78 vs. 1.63 mm), the wider and longer plaques (ratios ca. 3/4/ 13/1 vs. 3/3/11/1). The male genitalia of the two species also show a relationship, but differ in shapes of the main piece, distal piece, and parameres ( Figs. 69, 72 ). The metaventrite, the very complicated chaetotaxy of the tibiae, and the long setae of the metatarsi are illustrated with SEMs ( Figs. 308–309 , 314–315 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.78/0.68; head 0.29/0.37; pronotum 0.41/0.47, PA 0.41, PB 0.39; elytra 1.08/0.68. Dorsum piceous; legs and maxillary palpi dark brown.

Frons punctures ca. 1xef, slightly larger near eyes than medially; interstices shining, 1–6xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 2–4xpd, 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. 2–3xpd, as are interstices between punctures of a row, a few punctures random. 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. 3/4/13/1. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward blunt apex. Plaques very large, very narrowly separated, slightly more narrowly separated posteriorly than anteriorly, weakly raised. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 1.7x P2. All legs long and very slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia straight or very slightly arcuate, distal 1/3 widened on anterior surface, moderately long spine on medial surface at base of widened area. Mesotibia very slightly arcuate; mesotarsi with long, straight setae along lower margin. Metatibia straight or very slightly arcuate; metatarsi with long hair-like setae along lower margin. Fifth abdominal ventrite posteriorly markedly transversely raised. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 69). Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 396).

Etymology. "Hairy feet"; named in reference to the prominent setae of the meso- and metatarsi.

Distribution. Currently known from Areas 1, 5, and 6, with only one or two localities in each; elevation range 1220–2135 m ( Fig. 459 ).

Figures

FIGURE 67. Hydraena tarsotricha, holotype, dorsal and lateral habitus, and venter.

FIGURE 70. Hydraena tricosipes, holotype, dorsal and lateral habitus, and venter.

FIGURES 304–309. Scanning electron micrographs of H. tetana (304–307) and H. tarsotricha (308–309).

FIGURES 310–315. Scanning electron micrographs of H. tricosipes (310–313) and H. tarsotricha (314–315).

FIGURES 459–462. Geographical distributions of Hydraena species.

FIGURES 72–73. Aedeagi of holotypes. 72. H. tricosipes. 73. H. huonica.