Hydraena (Hydraenopsis) zetteli Freitag & Jäch, 2007

Freitag, Hendrik & Jäch, Manfred A., 2007, Revision of the species of Hydraena Kugelann (Coleoptera: Hydraenidae) from Palawan and Busuanga, with descriptions of eleven new species, and redescription of Hydraena (Hydraenopsis) scabra d’Orchymont, 1925, Zootaxa 1431, pp. 1-44 : 17-19

Hydraena (Hydraenopsis) zetteli Freitag & Jäch , sp. n.

(Figs. 6, 18a–h)

Type locality. Residual river pools, Mate, Municipality of Brooke’s Point, 08°46'N 117°50'E, southern Palawan, Philippines.

Type material. Holotype ɗ ( NMW): “ PHIL.: Palawan Brooke’s Point Mate, 31.3.1994 leg. Zettel (54)”, terminal parts of abdomen and aedeagus glued separately, one meso- and one metatarsus lacking (Fig. 6). Paratypes: 1 Ψ ( UPLB) “ PHIL.: Palawan, P. Princesa SSW Martarpi Cabayugan R.1 10°09'46''N 118°49'29'' E 1.3.2001, leg. Freitag (1)”; 1 ɗ ( NMW): “ PHIL.: Palawan, P. Princesa SSW Martarpi Cabayugan R1 10°09'46''N 118°49'29'' E 11.12.2000, leg. Freitag (2)”; 1 ɗ (CZW): “ PHIL.: Palawan, P. Princesa SSW Martarpi Cabayugan R.1, 10°09'46''N 118°49'29''E 11.XII.2000, leg. Freitag (a45)E”; 2 ɗɗ ( NMW, 1 ex. mutilated): “ PHIL.: Palawan, P. Princesa SE Manturon, Karst spring LS4R 10°09'29''N 118°53'30''E 18.III.2001, leg. Freitag (a50) E”; 3 ΨΨ (1 ex. NMW, 1 ex. CZW, mutilated; 1 ex. UPLB, mutilated): “ PHIL.: Palawan, P. Princesa SE Manturon, Cabayugan R. 10°09.486'N 118°53.493' E 3.3.2001, leg. Freitag (i6)”.

Description. Body 1.30–1.40 mm long. Habitus as in Fig. 6. Entire body reddish gold-brown; legs and maxillary palpi slightly paler; head usually not conspicuously darker.

Pronotum wider than long, broadest at middle, entire pronotum moderately densely punctate; punctures moderately large and moderately deeply impressed, interstices glabrous; foveae hardly perceptible or absent; lateral margins anteriorly and posteriorly slightly convergent; anterior angles rounded, posterior angles more or less rectangular, pronoto-elytral angle obtuse; lateral rim denticulate; anterior margin straight to slightly concave, posterior margin straight to slightly convex; lateral portions of pronotum moderately deflexed; lateral hypomeron approximately as broad as profemora, inner margin convex to biconvex; mesal hypomeron narrow, inconspicuous.

Elytra elongately oval, apically almost conjointly rounded, with ca. 14 longitudinal, more or less regular, not impressed rows of punctures (nine between suture and shoulder); punctures moderately large and moderately deeply impressed; interstices and intervals convex, glabrous; lateral margins of elytra widely explanate, almost reaching elytral apex, not or imperceptibly denticulate; inflexed lateral portion (pseudepipleuron) approximately as broad as metafemur; almost reaching elytral apex (ca. posterior 0.1), with indistinct foveae and one inconspicuous row of punctures; epipleuron narrow, inconspicuous.

Mesoventral longitudinal ridges less conspicuous than in other species; meso- and metaventrite pubescent; mesoventral intercoxal process moderately broad, truncate, moderately long, much narrower than pseudepipleuron, margins exserted, medially impressed; metaventral disc slightly impressed; metaventral plaques almost as broad as disc; intercoxal sternite large, slightly narrower than metafemur, slightly longer than broad; metaventrite and ventrites sparsely pubescent.

Femora with straight inner margins, outer margins conspicuously convex.

Aedeagus ( Figs. 18 a–c). Main piece slender, without setae (three micropores present); phallobase subsymmetric. Distal lobe not clearly delimited from main piece; ejaculatory duct distally ending in a short flagellum-like process, which is dorsally embedded in a less sclerotized hood-like structure. Parameres small, not articulately connected with main piece; left paramere short, inserted at about basal 0.45 of aedeagus, apically truncate, with a longitudinal ventro-mesal fringe of long setae and ca. seven moderately long setae (three ventral subapical, four lateral); right paramere shorter, apically attenuately rounded, inserted at ca. basal 0.6 of aedeagus, with a subapical tuft of long setae.

Gonocoxite ( Fig. 18 e) subsemicircular, rather transverse, more or less evenly rounded; lateral margin slightly emarginate subbasally; apical area of ventral plate almost as long as proximal area; condyles small; setae of subapical tufts slightly curved; dorsal plate simple, basally slightly surpassing outer plate, with one moderately large cavity.

Spermatheca ( Figs. 18 f–g). Proximal portion strongly curved, U-shaped; distal portion discoidal.

Secondary sexual characters. Male profemur with tiny denticle near base of ventral face (dissection of leg recommended). Male terminal sternite broadly pyriform, apical margin rounded, base broad; spiculum gastrale moderately long, distinctly curved basally ( Fig. 18 d). Male tergite X distinctly excised apically. Female tergite X ( Fig. 18 h) subsemicircular; disc moderately densely covered with squamose setae; subapical fringe of short trichoid setae medially interrupted; hyaline apical margin notched medially.

Differential diagnosis. Externally, Hydraena zetteli can easily be distinguished from H. nielshaggei and H. jojoorculloi by its bigger size, and from H. scabra by moderately large and moderately deeply impressed elytral and pronotal punctures. From all species described above it differs by its broad elytral gutter (almost reaching elytral apex) and more or less regularly reddish to gold-brown colour. Its aedeagus superficially resembles that of H. nielshaggei , but it can be distinguished from all species by is long parameral setae. Female tergite X differs from all other Philippine species known so far by presence of subbasal squamose setae.

Distribution ( Fig. 30 ). This species is known from one creek in Mate, Brooke’s Point, southern Palawan, and from the Cabayugan River near Puerto Princesa, central Palawan.

Ecology. The holotype was collected in a residual pool of a riverbed during the dry season. All remaining specimens were caught in emergence traps positioned at banks of headwater creeks of rather undisturbed, forest-covered areas.

Etymology. Named for Dr. Herbert Zettel (Natural History Museum of Vienna, Austria), famous specialist of water bugs and expert on the zoogeography of the Philippines.

Figures

FIGURE 18. Hydraena zetteli sp. n. a – c) aedeagus (paratype from Cabayugan, Palawan) in ventral (parameral setae omitted), dorsal (parameral tufts omitted) and lateral view (tuft of left paramere omitted); d) male sternite X and spiculum; e) gonocoxite; f – g) spermatheca; h) female tergite X.

FIGURE 30. Collecting sites and geographical distribution of Hydraena species in Palawan and Busuanga, including enlarged map of St. Paul National Park: Hydraena scabra d’Orchymont, H. jojoorculloi sp. n., H. nielshaggei sp. n., H. zetteli sp. n., H. castanescens sp. n., H. claudia sp. n., H. kodadai sp. n.