Introduction of the Exocelina ekari-group with descriptions of 22 new species from New Guinea (Coleoptera, Dytiscidae, Copelatinae)

Abstract The Exocelina ekari-group is here introduced and defined mainly on the basis of a discontinuous outline of the median lobe of the aedeagus. The group is known only from New Guinea (Indonesia and Papua New Guinea). It contained four species to date: Exocelina astrophallus (Balke, 1998), Exocelina atowaso (Shaverdo, Sagata & Balke, 2005), Exocelina munaso (Shaverdo, Sagata & Balke, 2005), and Exocelina polita (Sharp, 1882). Twenty two new species are described herein: Exocelina alexanderi sp. n., Exocelina anggiensis sp. n., Exocelina arfakensis sp. n., Exocelina bifida sp. n., Exocelina brahminensis sp. n., Exocelina bundiensis sp. n., Exocelina edeltraudae sp. n., Exocelina ekari sp. n., Exocelina eme sp. n., Exocelina evelyncheesmanae sp. n., Exocelina hansferyi sp. n., Exocelina irianensis sp. n., Exocelina kakapupu sp. n., Exocelina knoepfchen sp. n., Exocelina oceai sp. n., Exocelina pseudosoppi sp. n., Exocelina soppi sp. n., Exocelina unipo sp. n., Exocelina utowaensis sp. n., Exocelina waigeoensis sp. n., Exocelina weylandensis sp. n., and Exocelina wondiwoiensis sp. n. The lectotype of Copelatus politus Sharp, 1882 is designated. A checklist and identification key to all species of the group are provided and important diagnostic characters (habitus, color, male antennae and protarsomeres 4–5, median lobes and parameres) are illustrated. Data on the distribution and habitat requirements are given. Representatives of the Exocelina ekari-group are so far mostly known from lowland to lower montane habitats of the northern and central parts of New Guinea, the group is less diverse in higher altitudes.


Introduction
All specimen data are quoted as they appear on the labels attached to the specimens. Label text is cited using quotation marks. Comments in square brackets are ours. We extracted DNA and obtained DNA sequence data for some of the species/specimens, marked with individual DNA extraction numbers (e.g. "256 DNA M. Balke"). All types of the herein described specimens are provided with red labels. The female specimens, identification of which is difficult or sometimes impossible, are included in the type series only when collected with males of respective species and do not show external morphological differences from them. If two or more morphologically similar species collected together (males found together), their females were not included in the types series of the respective species but were mentioned under additional material.
Measurements were taken with a Wild M10 stereomicroscope. The following abbreviations were used: TL (total body length), TL-H (total body length without head), MW (maximum body width), and hw (handwritten). Number of the ventral setae of the male protarsomere 5 is given only for one specimen of each species, which was mounted on a glass slide (see below) for drawing. This character was found not very useful for the species identification since it is possible to make a general statement of the setation pattern (short/long, dense/sparse) but not to count them with certainty at the magnification of normal dissecting scopes. The potential phylogenetic information content of this character will be studied in a further work.
Drawings were made with the aid of a camera lucida attached to a Leica DM 2500 microscope. For detailed study and drawing, antennae, protarsi, and genitalia were removed and mounted on glass slides with DMHF (dimethyl hydantoin formaldehyde) as temporary preparations. The drawings were scanned and edited, using the software Adobe Illustrator CS5.1. Arrangement of the figures follows the species order in the key.
The terminology to denote the orientation of the genitalia (ventral for median lobe and dorsal and external for paramere) follows Miller & Nilsson (2003). The term "sternite 7" is used to indicate the last abdominal sternite (ventrite). Administrative divisions of Indonesia and Papua New Guinea follow information from .

Diagnosis of the Exocelina ekari-group
This group is newly introduced herein, and the following diagnostic characters of the group are proposed: -beetles small or middle-sized (TL-H 3.0-5.2 mm); -habitus oblong-oval (broadest approximately at elytral middle), with rounded pronotal and elytral sides, body outline continuous; -pronotum short, trapezoidal, with posterior angles not drawn backwards; -coloration red, reddish-brown to piceous, mainly uniform, sometimes with paler head and pronotum and darker elytra; -microreticulation and punctation of dorsal suface very fine to strongly impressed, so that beetles shiny to matt dorsally; -metacoxae and abdominal sternites 2-6 (and 7 in males) with thin, almost longitudinal striae/strioles; -pronotum and elytra without striae or strioles; -pronotum with or without lateral bead; -male antennomeres simple or antennomeres 3-10 differently modified; -male protarsomeres 1-3 not expanded laterally; -male protarsomere 4 cylindrical, narrow, with small to large anterolateral hook; -male protarsomere 5 not modified: long and narrow, without expansion and concavity, ventrally with two sparse rows of relatively short setae; -median lobe of aedeagus with discontinuous outline in ventral view and sometimes in lateral view; -ventral sclerite of median lobe more or less deeply divided on the middle, in some species like two long subequal ventral sclerites, because of strong sclerotisation of its lateral sides; -apical part of median lobe with or without setae; -paramere with or without notch on dorsal side; -paramere with long setae occupying whole dorsal side, in most species these setae denser and stronger on subdistal part of paramere and can be of different length and shape.
The main diagnostic character of the group is discontinuous outline of the median lobe of the aedeagus in ventral view and sometimes in lateral view (showed with arrows in Figs 1C,D). The discontinuous outline of the median lobe is present due to curved, plicate, or corrugated lateral sides of the lobe. It can be differently developed, for example very strongly, forming submedian constriction, as e.g. in Figs 2C,3C,and 4D,or  Male: Antennomeres 3-4 strongly enlarged and triangular (3 larger than 4), 5-6 distinctly enlarged, 7 somewhat enlarged (Fig. 9A); antennomeres 3-6 rugose ventrally. Protarsomere 4 with small (only slightly larger than more laterally situated large seta), thin, slightly curved anterolateral hook. Protarsomere 5 ventrally with anterior row of 9 short setae and posterior row of 7 short setae (Fig. 9B). Abdominal sternite 7 with 8-10 lateral striae on each side. Median lobe with strong submedian constriction in ventral view, apex of median lobe elongate in lateral view and narrower in ventral view (Figs 9C,D). Paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae (Fig. 9E).
Distribution. Indonesia: West Papua Province: Manokwari Regency. The species is known only from the type locality (Fig. 50).

Exocelina arfakensis
Diagnosis. Beetle middle-sized, piceous, shiny but with evident dorsal punctation; pronotum with distinct lateral bead; male antennomeres 3-4 strongly enlarged and triangular (3 larger than 4), 5-6 distinctly enlarged, 7 somewhat enlarged; male protarsomere 4 with small, thick (evidently thicker and slightly longer than more laterally situated large seta), slightly curved anterolateral hook; median lobe with strong submedian constriction in ventral view, apex of median lobe elongate in lateral view and narrower in ventral view; paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae.
Surface sculpture: Head with very dense, coarse punctation (spaces between punctures 1-2 times size of punctures), especially on vertex. Pronotum and elytra with punctation much finer and sparser. Pronotum and elytra with somewhat stronger impressed microreticulation, but dorsal surface still shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, rounded and smooth anteriorly, with small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Protarsomere 4 with small, thick (evidently thicker and slightly longer than more laterally situated large seta), slightly curved anterolateral hook. Protarsomere 5 ventrally with anterior row of 11 short setae and posterior row 5 short setae (Fig. 10B). Abdominal sternite 7 with 6-8 lateral striae on each side. Median lobe with strong submedian constriction in ventral view, apex of median lobe elongate in lateral view and narrower in ventral view (Figs 10C,D). Paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae (Fig. 10E).
Female: Dorsal punctation slightly coarser, antennae simple, sternite 7 without striae. Distribution. Indonesia: West Papua Province: Manokwari Regency. The species is known only from the Arfak Mountains, the eastern part of Bird's head (Fig. 50).
Female: Without evident differences in external morphology from male, except for abdominal sternite 7 without striae.

Exocelina atowaso
Additions and corrections to the description. For the complete description and illustrations see Shaverdo et al. (2005).
Male: Protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook. Median lobe with very strong submedian constriction and small subapical processes in ventral view and with almost rounded apex bearing setae in lateral view. Paramere without notch on dorsal side, with relatively dense, long, thin setae. See Figs 9, 14a, b in Shaverdo et al. (2005).
Female: Without evident differences in external morphology from male, except for abdominal sternite 7 without striae.
Diagnosis. Beetle small, dark brown to piceous, shiny; pronotum without lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe with strong submedian constriction and apex bifid: with small dorsal extension; paramere with notch on dorsal side and subdistal part elongate, with dense, long, thin setae. The species is well recognizable by its characteristic male genitalia.
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with much finer and sparser punctation than on head. Elytra with very sparse and fine punctation, almost invisible. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum without lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly less rounded, smooth, with small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Without evident differences in external morphology from male, except for abdominal sternite 7 without striae.
Distribution. Indonesia: Papua Province, Jayawijaya Regency. This species is known only from the type locality (Fig. 50).

Exocelina brahminensis
Diagnosis. Beetle small, piceous, with reddish brown head and pronotum, shiny; pronotum without lateral bead or with weak traces of lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe with weak submedian constriction in ventral view; paramere with strong notch on dorsal side, with notch tip sharply pointed, and subdistal part elongate, with upper setae thin and more numerous and lower setae shorter, thick, and flattend. The species is similar to E. eme sp. n., from which it differs by simple male antennae and the shape of the male genialia, especially by the strong notch of the paramere and its sharply poined tip.
Surface sculpture: as in E. eme sp. n. Structures: Pronotum without lateral bead or with weak traces of lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly smooth, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Traces of the pronotal lateral bead developed stronger in some specimens; abdominal sternite 7 without striae.
Etymology. The name refers to the village Brahmin where this species was first discovered. The species name is an adjective in the nominative singular. Diagnosis. Beetles small, dark brown, dorsally less strongly punctate than E. hansferyi, submatt; pronotum with lateral bead; male antennomeres 3-5 enlarged, 6-8 slightly enlarged; male protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe with strong submedian constriction and proximal part narrower, apex of median lobe narrower in lateral view; paramere with distinct notch on dorsal side and subdistal part elongate, with less numerous, long, thin setae.
Surface sculpture: Similar to E. hansferyi, but with less strong punctation and microreticulation. Head with very dense punctation (spaces between punctures 1-2 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures less than diameter of cells of microreticulation. Pronotum with finer, sparser punctation than on head. Elytra with finer, sparser and more evenly distributed punctation than on pronotum. Pronotum and elytra with rather strongly impressed microreticulation, dorsal surface, thus, submatt. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine, rather dense punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, without anterolateral extensions. Blade of prosternal process lanceolate, rather narrow, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 slightly truncate apically.
Female: Antennae simple, abdominal sternite 7 without striae. Distribution. Papua New Guinea. The species is known from Madang and Eastern Highlands Provinces (Fig. 50).

Exocelina edeltraudae
Diagnosis. Beetle middle-sized, piceous, submatt; pronotum with distinct lateral bead; male sternite 7 slightly to distinctly concave apically; male antennomeres 3-5 distinctly enlarged, almost equally in size and shape, antennomeres 6-8 enlarged; male protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe with very strong submedian constriction and proximal part very broad in ventral view, apex of median lobe pointed and strongly curved downwards in lateral; paramere with distinct notch on dorsal side and subdistal part elongate, with numerous, dense, long, thin setae. The species is well recognizable by the modified antennae of the males and the shape of the median lobe.
Surface sculpture: Head with dense, coarse punctation (spaces between punctures 1-3 times size of punctures), especially on vertex. Pronotum with punctation much finer, sparser, and more evenly distributed than on head. Elytra with extremely sparse and fine punctation. Pronotum and elytra with strongly impressed microreticulation, dorsal surface, thus, submatt. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, rounded and smooth anteriorly, with small anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded or concave apically.
Distribution. Papua New Guinea. The species is known from Western Highlands and Southern Highlands Provinces (Fig. 50).
Etymology. Dedicated to Edeltraud Tötzl, senior author's mother-in-law: "With my sincere thankfulness. Without your help with my children, my scientific work was not possible during last six years". The species name is a noun in the genitive case. Additional material. 10 females "IRIAN JAYA: Paniai Prov. road Nabire-Ilaga, km 54 10.9.1996, 900m leg. M. Balke (96 # 19)" (NHMW). These females are most likely a mixture of three species: E. ekari sp. n., E. weylandensis sp. n., and E. kakapupu sp .n. Also see the paragraph of E. irianensis sp. n.

Exocelina ekari
Diagnosis. Beetle small, dark brown, with slightly paler anterior part of head and pronotal sides, shiny; pronotum without lateral bead; male antennomeres 3-10 stout; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe with strong submedian constriction and apical part very broad in ventral view and slightly flattened in lateral view; paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae.
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with much finer and sparser punctation than on head. Elytra with very sparse and fine punctation, almost invisible. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum without lateral bead or with weak traces of lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly rounded, smooth, with very small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Male: Antennomeres 3-10 stout (Fig. 16A). Protarsomere 4 with large, thick, strongly curved anterolateral hook. Protarsomere 5 ventrally with anterior row of 10 short setae and posterior row of 5 short setae (Fig. 16B). Abdominal sternite 7 with 1-5 lateral striae on each side. Median lobe with strong submedian constriction and apical part very broad in ventral view and somehow flattened in lateral view (Figs 16C,D). Paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae (Fig. 16E).
Female: Antennae more slender, abdominal sternite 7 without striae. Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).
Etymology. This species is named for the native community (Ekari people) which inhabits the area from which the specimens have been collected. The name is a noun in the nominative standing in apposition. Diagnosis. Beetle small, piceous, shiny; pronotum without lateral bead; male antennomeres 3-10 slightly stout; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe with weak submedian constriction in ventral view; paramere with notch on dorsal side and subdistal part elongate, with upper setae thin and less numerous and lower setae long, thick, somewhat flattend, and curved at apex.
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with much finer and sparser punctation than on head. Elytra with very sparse and fine punctation, almost invisible. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum without lateral bead or with weak traces of lateral bead in females. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly smooth, without anterolateral extensions. Blade of prosternal process lanceolate, narrow, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Antenna slightly more slender; pronotum with weak traces of lateral bead; abdominal sternite 7 without striae.
Distribution. Indonesia: Papua Province, Jayawijaya Regency. This species is known only from the type locality ( Fig. 50).
Etymology. The species is named for the Eme River, from a tributary of which it has been collected. The name is a noun in the nominative singular standing in apposition.  Mt. Nok, 500m, 11.ii.1994, 00.05.076S, 130.44.586E, Balke (BH 11)", one of them additionally with a green label "DNA M.Balke 1276" (NHMW, ZSM).

Exocelina evelyncheesmanae
Diagnosis. Beetle middle-sized, dark brown to piceous (teneral specimens reddish-brown), shiny; pronotum with lateral bead; male antennomeres 3-7 very slightly enlarged, antennomere 3 slightly more triangular than other antennomeres; male protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe with strong submedian constriction in ventral view and truncate apex in lateral view; paramere with notch on dorsal side and subdistal part short and small, with less numerous, relatively short, thick, and flattened setae. The species occurs together with E. waigeoensis sp. n. and can be distinguished from it by its larger size (also females) and the shape of the medial lobe.
Surface sculpture: Head with dense punctation (spaces between punctures 1-4 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head. Elytra with very sparse and extremely fine punctation. Pronotum and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead, absent in anterior angles. Base of prosternum and neck of prosternal process with distinct ridge, smooth and slightly rounded anteriorly (less than in E. waigeoensis sp. n.), without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Antennae more slender, abdominal sternite 7 without striae. Distribution. Indonesia: West Papua Province: Raja Ampat Regency. The species is known only from the type locality (Fig. 50).
Etymology. The species is named for the incredible collector and adventurer, Miss Lucy Evelyn Cheesman who discovered this species. The species name is a noun in the genitive case. Diagnosis. Beetle small, yellowish-red to brown, dorsally strongly punctate, submatt; pronotum with lateral bead; male antennomeres 3-5 enlarged, 6-8 slightly enlarged; male protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe with strong submedian constriction and proximal part narrower, apex of median lobe rather broad in lateral view; paramere with shallow notch on dorsal side and subdistal part elongate, with less numerous, long, thin setae.
Surface sculpture: Head with very dense punctation (spaces between punctures 1-2 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures equal diameter of cells of microreticulation. Pronotum and elytra with finer, sparser, and more evenly distributed punctation than on head. Pronotum and elytra with rather strongly impressed microreticulation, dorsal surface, thus, submatt. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine, rather dense punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, smooth and slightly rounded anteriorly, with small anterolateral extensions. Blade of prosternal process lanceolate, rather narrow, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 slightly truncate apically.
Female: Antennae simple, abdominal sternite 7 without striae. Distribution. Papua New Guinea: Morobe Province. The species is known only from the type locality (Fig. 50).
Etymology. The species is named after our friend and colleague Dr. Hans Fery (Berlin). The name is a noun in the genitive case. Diagnosis. Beetle small, reddish-brown to dark brown, usually with paler head and pronotal sides; shiny; pronotum without lateral bead; male antennomeres 3-5 distinctly enlarged; male protarsomere 4 with large, thick, evidently curved anterolateral hook; median lobe with very strong submedian constriction, distal and proximal parts equally broad, and symmetrical apex in ventral view; paramere with shallow notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae. The species differs from other ones by the pronotum without lateral bead and modified antennae of the males.
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with a little sparser but much finer punctation than on head, almost invisible. Elytra with extremely sparse and fine punctation. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum without lateral bead, in some specimens with indistinct traces of bead. Base of prosternum and neck of prosternal process with distinct ridge, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly truncate apically, in some specimens very distinctly, in some less.
Female: Antenna simple; traces of bead on pronotal sides are more often observed than in males; abdominal sternite 7 without striae.
Etymology. The name is derived from the Biak (northern coast of New Guinea) islanders' word "Irian", which means "hot island emerging from the sea" and refers to New Guinea. The species name is an adjective in the nominative singular.  These females most likely belong to E. kakapupu sp. n. However they are not included in the type series, since four specimens of E. weylandensis sp. n. have been collected from this locality too, and, therefore, some of females might belong to this species. Also see in the paragraph of E. irianensis sp. n. and E. ekari sp. n.

Exocelina kakapupu
Diagnosis. Beetle small, very similar to E. soppi sp. n. and E. pseudosoppi sp. n. in size and coloration; pronotum without lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe with strong submedian constriction in ventral view and almost truncate apex in lateral view; paramere with notch on dorsal side and elongate subdistal part, with numerous, dense, long, thin setae; setae of proximal part longer, thicker, distinctly visible.
Surface sculpture: Punctation as in E. soppi sp. n. and E. pseudosoppi sp. n. but denser and coarser; microreticulation evidently stronger than in these species.
Structures: Pronotum without lateral bead or with weak traces of lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly rounded, smooth, with very small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly truncate apically.
Female: Without evident differences in external morphology from male, except for abdominal sternite 7 without striae.
Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).

Exocelina knoepfchen
Diagnosis. Beetle middle-sized, uniformly dark brown or head and pronotum slightly paler; pronotum with distinct lateral bead; male antennomere 3 evidently larger than other; male protarsomere 4 with very small (smaller than more laterally situated large seta), thin, slightly curved anterolateral hook; median lobe with very weak submedian constriction, apex of median lobe almost rounded in lateral view; paramere without notch on dorsal side, with relatively short, sparse, thin setae. The species is well recognizable by its larger size, the modified antennae of the males, and paramere distinctly longer than median lobe.
Coloration: Dorsally uniformly dark brown or head and pronotum slightly paler, with paler (yellowish-red to reddish-brown) anterior margin of head, lateral sides of pronotum, and narrow bands along elytral suture; head appendages yellowish-red to reddishbrown, legs slightly darker (Fig. 33).
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head. Elytra with very sparse and fine punctation, almost invisible. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with strong, sharp ridge, without anterolateral extensions. Blade of prosternal process lanceolate, narrow, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Etymology. The species is named for an old friend of M. Balke. The name is a noun in the nominative singular standing in apposition.
Additions and corrections to the description. For the complete description and illustrations see Shaverdo et al. (2005).
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with sharp ridge and well developed anterolateral extensions. Blade of prosternal process lanceolate, rather narrow, with strong longitudinal convexity; neck and blade of prosternal process evenly jointed, except for weak concavity in front of jointion of protrochanters.
Male: Protarsomere 4 with large, thick, strongly curved anterolateral hook. Median lobe without submedian constriction but with lateral folds in ventral view and with apex pointed and curved downwards in lateral view. Paramere without notch on dorsal side, with relatively dense, long, thin setae. See Figs 10, 15a, b in Shaverdo et al. (2005).
Female: Without evident differences in external morphology from male, except for abdominal sternite 7 without striae.
Distribution. Papua New Guinea. The species is known only from Crater Mountain, Simbu and Eastern Highlands Provinces (Fig. 50). Diagnosis. Beetle small, reddish-brown to brown; pronotum with narrow lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe slender, with weak submedian constriction in ventral view and elongate apex in lateral view; paramere with strong notch on dorsal side and subdistal part short and large, with long, dense, curved at apex setae.
Surface sculpture: Head with dense punctation (spaces between punctures 1-4 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head. Elytra with very sparse and fine punctation, almost invisible. Pronotum and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct but narrow lateral bead, in some specimens reduced at posterior angles. Base of prosternum and neck of prosternal process with distinct ridge, smooth and rounded anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Some specimens with pronotal lateral bead reduced at posterior angles; abdominal sternite 7 without striae.
Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).
Etymology. The species is named for "Doc" Ocea Megay, one of our Ekari fellows and most enthusiastic fieldworker who died from a snake bite shortly after we have collected this species. He is buried in Topo. The species name is a noun in the genitive case. (Sharp, 1882) http://species-id.net/wiki/Exocelina_polita 37 Copelatus politus Sharp, 1882: 568. Copelatus politus Sharp, 1882: Régimbart, 1899 ;Zimmermann, 1919Zimmermann, : 198 (cat.), 1920; Guéorguiev, 1968: 34 (cat.) Shaverdo, Hendrich & Balke 2012" [red, printed] (BMNH). Notes: The lectotype is designated in order to support the stability of nomenclature since it is not clear from the original description that it has been based on the single male. The genialia are partly damaged.

Exocelina polita
Diagnosis. Beetle middle-sized, brown, shiny, with almost invisible dorsal punctation; pronotum with distinct lateral bead; male antennomeres 3-4 strongly enlarged and triangular (3 distinctly larger than 4), 5-6 distinctly enlarged, 7 somewhat enlarged; male protarsomere 4 with small, thin, slightly curved anterolateral hook; median lobe with strong submedian constriction in ventral view, apex of median lobe elongate in lateral view and broader in ventral view; paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae.
Surface sculpture: Head with dense punctation (spaces between punctures 1-2 times size of punctures), evidently finer and sparser anteriorly; diameter of punc-tures smaller or equal than diameter of cells of microreticulation. Pronotum with distinctly finer, sparser, and more evenly distributed punctation than on head. Elytra with very sparse and fine punctation, almost invisible. Head, pronotum, and elytra with strongly impressed microreticulation, dorsal surface shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, rounded and smooth anteriorly, with very small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Unknown. Distribution. Indonesia: West Papua Province: Manokwari Regency. The species is known only from the lectotype from the Arfak Mountains, the eastern part of Bird's head (Fig. 50). Diagnosis. Beetle small, very similar to E. soppi sp. n., differing from it in the shape of the anterior part of the prosternum, simple male antennae, and male genitalia: truncate apex of the median lobe, stronger submedian constriction, and the shape and setation of the paramere: shallow notch on the dorsal side and subdistal part elongate, with a strong tuft of thicker, somewhat flattend, and strongly curved at apex setae.
Surface sculpture: Punctation and microreticulation as in E. soppi sp. n. Structures: Pronotum without lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly evidently less rounded and smooth than in E. soppi sp. n., with very small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Without evident differences in external morphology from male, except for abdominal sternite 7 without striae.
Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).
Etymology. Long time this species was mistaken for E. soppi sp. n. The name is a noun in the nominative singular standing in apposition. Diagnosis. Beetle small, dark brown, often with paler head and pronotal sides, shiny; pronotum without lateral bead; male antennomeres 3-10 slightly stout; male protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe with weak submedian constriction in ventral view and elongate apex in lateral view; paramere with notch on dorsal side and subdistal part short and small, with large brush of thick, somewhat flattend, long, curved at apex setae.
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with much sparser and finer punctation than on head. Elytra with extremely sparse and fine punctation. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum without lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly rounded, smooth, with very small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically, in some species broadly truncate.
Female: Antennae slightly more slender, abdominal sternite 7 without striae. Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).
Etymology. This species is dedicated to our old buddy Michael Sopp (Berlin). The species name is a noun in the genitive case. Diagnosis. Beetles small, very similar to E. kakapupu sp. n. except for male antennomeres 3-10 stout, male genitalia, weaker dorsal punctation and microreticulaton, and much more striated male sternite 7. Also protarsomere 4 with large, thick, strongly curved anterolateral hook, which apical part longer than in E. kakapupu sp. n. Median lobe with weak submedian constriction in ventral view and elongate apex in lateral view; paramere with notch on dorsal side and elongate subdistal part, with numerous, dense, long, thin setae; setae of proximal part shorter, thiner, often hardly visible.
Surface sculpture: Punctation and microreticulation evidently weaker than in E. kakapupu sp. n., more similar to that in E. soppi sp. n.
Structures: Pronotum without lateral bead or with weak traces of lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly rounded, with weak transverse lines, small anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Antennae more slender, abdominal sternite 7 without striae. Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).
Etymology. The species is named for the type locality. The name is a noun in the nominative singular standing in apposition. Diagnosis. Beetle small, piceous, shiny; pronotum without lateral bead; male antennomeres 3-10 slightly enlarged; sternite 7 concave; male protarsomere 4 with large, thick, strongly curved anterolateral hook; median lobe long, with very weak submedian constriction and apex narrow in ventral view; paramere large, with strong notch on dorsal side and subdistal part very broad, subquadrate, with dense, long, relatively thick, curved at apex setae. The species is well recognizable by its characteristic male genitalia and concave (also in females) abdominal sternite 7.
Surface sculpture: Head with dense punctation (spaces between punctures 1-3 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with much finer and sparser punctation than on head. Elytra with extremely sparse and fine punctation. Head, pronotum, and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum without lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, anteriorly smooth, without anterolateral extensions. Blade of prosternal process lanceolate, narrow, convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 concave apically.
Female: Antenna distinctly more slender than in male; abdominal sternite 7 only slightly concave apically, without striae.
Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known from the lower Utowa River area and one of its tributaries (Fig. 50).
Diagnosis. Beetle small, reddish-brown, shiny; pronotum with distinct lateral bead; male antennomeres 3-7 very slightly enlarged, antennomere 3 slightly more triangular than other antennomeres; male protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe with strong submedian constriction in ventral view and elongate apex in lateral view; paramere with notch on dorsal side and subdistal part short and small, with less numerous, relatively short, thick, and flattened setae.
Description. Size and shape: Beetle small (TL-H 3.45-3.7 mm, TL 3.75-4.1 mm, MW 1.8-2.0 mm), with oblong-oval habitus, broadest at elytral middle. Coloration: Head and pronotum uniformly reddish-brown, darker posterior eyes and sometimes on anterior margin of pronotum, elytra dark brown, head appendages yellow to yellowish-red, legs distally darker than head appendages, hind legs to reddish-brown (Fig.  28). Note: Perhaps, the coloration can be darker: the type series includes several teneral beetles and it is possible that the rest specimens are not completely sclerotized.
Surface sculpture: Head with dense punctation (spaces between punctures 1-4 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head. Elytra with very sparse and extremely fine punctation. Pronotum and elytra with weakly impressed microreticulation, dorsal surface, thus, shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal sternites with distinct microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal sternites.
Structures: Pronotum with distinct lateral bead, absent in anterior angles. Base of prosternum and neck of prosternal process with distinct ridge, smooth and rounded anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Antennae more slender, abdominal sternite 7 without striae. Distribution. Indonesia: West Papua Province: Raja Ampat Regency. The species is known only from the type locality (Fig. 50).
Etymology. The species is named in reference to its distribution: Waigeo Island. The name is an adjective in the nominative singular. Additional material. See in the paragraph of E. irianensis sp. n., E. ekari sp. n., and E. kakapupu sp. n.

Exocelina weylandensis
Diagnosis. Beetle small, reddish-brown to brown, with paler head and pronotal sides, shiny; pronotum without lateral bead; male antennomeres 3-10 stout; protarsomere 4 with middle-sized, slender, evidently curved anterolateral hook; median lobe slender, with very weak submedian constriction in ventral view; paramere with notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, flattened, slightly curved at apex setae.
Surface sculpture: Punctation and microreticulation as in E. irianensis sp. n. Structures: Pronotum without lateral bead, in a very few specimens with indistinct traces of bead. Base of prosternum and neck of prosternal process with distinct ridge, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly rounded apically.
Female: Antennae more slender, abdominal sternite 7 without striae. Distribution. Indonesia: Papua Province: Nabire and Paniai Regencies. This species is known only from the type locality area (Fig. 50).
Etymology. Derived from the name of the range, Weyland, at the northern edge of which the type locality is situated. The species name is an adjective in the nominative singular. Diagnosis. Beetle small, externally very similar to E. irianensis sp. n. but darker: dark brown to piceous, with head (in some specimens only its anterior part) paler; shiny; pronotum without lateral bead; male antennomeres 3-5 distinctly enlarged; male protarsomere 4 with large, thick, evidently curved anterolateral hook; median lobe with very strong submedian constriction, distal and proximal parts equally broad, and asymmetrical apex in ventral view; paramere with shallow notch on dorsal side and subdistal part short and small, with not numerous, relatively short, thick, and flattened setae. The species is very similar to the previous one and differs from it only by the assymetrical shape of the apex of the median lobe.
Structures: Pronotum without lateral bead, in some specimens with indistinct traces of lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal sternite 7 broadly truncate apically.
Female: Antenna simple; traces of bead on pronotal sides are more often observed than in males; abdominal sternite 7 without striae.
Distribution. Indonesia: West Papua Province: Teluk Wondama Regency. This species is known from the Wondiwoi Mountains of Wandammen Peninsula (Fig. 50).
Etymology. The species is named for the type area, Wondiwoi Mountains. The name is an adjective in the nominative singular.

Key to species of the Exocelina ekari-group
The key is based mostly on the male characters. In many cases females cannot be assigned to species due to similarity of their external and internal structures (for female genitalia see Figs 17a and 17b in Shaverdo et al. (2005). Some species are rather similar in point of external morphology, therefore, in most cases the male genitalia need to be studied for reliable species identification. Numbers in brackets refer to an arrangement of the species descriptions above. Beetle larger, TL-H: 4.8-5.0 mm (Fig. 24), male protarsomere 4 with large, thick, strongly curved anterolateral hook, apex of median lobe pointed and curved downwards in lateral view (Figs 10, 15a in Shaverdo et al. (2005)  Beetle smaller, TL-H: 3.35-3.8 mm (Fig. 26), male antenna simple, male protarsomere 4 with large, thick, strongly curved anterolateral hook, median lobe more slender in ventral view, and paramere with strong notch on dorsal side and subdistal part short and large (Fig. 1)  Beetle dorsally submatt, with distinct punctation (Fig. 27), male antennomeres simple, median lobe short and with extremely strongly discontinuous (curved, plicate) outline, paramere with shallow notch on dorsal side and subdistal part elongate, with dense, long, thin setae (Figs 37, 46, 64 in Balke (1998 (Figs 28,29), male antennomere 3-7 very slightly enlarged, antennomere 3 slightly more triangular than other antennomeres, median lobe longer and without such a strong modification, paramere with notch on dorsal side and subdistal part short and small, with less numerous, shorter, thick, and flattened setae (Figs 2, 3) (Fig. 28), apex of median lobe elongate in lateral view (Fig. 2D) (Fig. 29), apex of median lobe truncate in lateral view (Fig. 3D)  Male antennomeres 3-5 strongly enlarged (Fig. 4A), beetle dorsally piceous (Fig. 30), male sternite 7 slightly to distinctly concave apically, median lobe with very strong median constriction and proximal part very broad in ventral view, apex of median lobe pointed and strongly curved downwards in lateral view, subdistal part of paramere with numerous, dense, long setae  Male antennomeres 3 and 4 more strongly elongated, more equal in size and shape (Fig. 8A), elytral punctation fine, coloration dark brown to piceous (Fig. 34) Prosternal ridge anteriorly evidently less rounded and smooth, male antenna simple, median lobe with apex truncate in lateral view and submedian constriction stronger in ventral view, paramere with shallow notch on dorsal side and subdistal part elongate, with strong tuft of thicker, somewhat flattend, and strongly curved at apex setae (Figs 19A (Shaverdo, Sagata & Balke, 2005) 25 E. atowaso (Shaverdo, Sagata & Balke, 2005) 26 E. oceai sp. n. 27 E. astrophallus

Habitats
The species are always running water associated, but they do avoid water movement. This appears paradox, but it is a very important microhabitat preference especially in many tropical ecosystems. New Guinean Exocelina species are found in streambeds, usually the smaller the better, at the edge where there are small backflows. There, the beetles are only found where there is no current at all. Small isolated water holes, usually on heavy red clay, are another preferred habitat. The beetles may be found on wet rocks along streambeds, hiding under leaves, in rock pools, or tiny water filled holes in rocks, along the streams, as well as in rest pools of intermittent streams, in wet gravel, underneath of rocks in dry streambeds, and in tiny, shallow water holes on slopes above the actual spring of a stream. It is worth to note that it is often the best approach to climb a ridge up to a suitable point and then descend a steep slope until the first temporary water holes occur. This yields often large series of specimens -such as on Waigeo Island, on Mountain Nok, where Exocelina beetles were extremely common in such habitats: the first stagnant water available underneath the summit, often where roots and rocks contained water and formed small puddles on the clay. Few meters below, where the first order stream was already running slowly, we did hardly encounter specimens. In limestone areas, such as on Batanta Island and in Fak Fak (species treated in a future paper), we followed a stream up to a point where the entire, 10 m wide, streambed was dry. Specimens were found in small water holes on large limestone boulders. Sometimes, Exocelina species occur on sandy/gravelly river banks, where they can either be seen swimming around in small pools, or are collected by removing rocks from the wet ground where a small puddle will form in the imprint, and specimens can then be washed out of the gravel by hand and with a strainer. At the edge of large (montane) rivers, we found large numbers of specimens in pools along the river. In general, clay, mossy rocks, as well as presence of rough sand/gravel indicate rich Exocelina fauna, as this allows the beetles to hide well and dig into the ground to avoid flooding of streams. Shaded locations are preferred -often, the only shaded spot along a stretch of river, otherwise fully exposed, contains all Exocelina beetles that can be found.
Figures 51-53 illustrate some typical habitats and their microhabitats, but there are countless variations of the general theme. Fast flowing streams on steep slopes such as in Figs 51,53 are notoriously hard to sample, as this requires hiking up the stream in the water, on very slippery ground and cutting through vegetation across the streambed in order to find suitable microhabitats. In situations like that, it might be advisable also to travel around and try to find possibly dry lower order streams, which might contain the same species. Riverbank habitats (Fig. 52) are, on the other hand, much easier to access and to sample, and it is helpful to utilize strong gloves to dig through the gravel, removing stone by stone, and excavate gravel (which is often very sharp) in order to crate small puddles which will eventually reveal Exocelina beetles out of the interstitial. For more information see http:// zsm-entomology.de/wiki/Coleoptera_Fieldwork.