Taxonomic revision of New Guinea diving beetles of the Exocelina danae group, with the description of ten new species (Coleoptera, Dytiscidae, Copelatinae)

Abstract Ten new species of Exocelina Broun, 1886 from New Guinea are described: Exocelina andakombensis sp. n., Exocelina garaina sp. n., Exocelina injiensis sp. n., Exocelina kabwumensis sp. n., Exocelina marawaga sp. n., Exocelina posmani sp. n., Exocelina tekadu sp. n., Exocelina varirata sp. n., Exocelina wareaga sp. n., and Exocelina woitapensis sp. n. All of them together with five already described species are united into the newly defined Exocelina danae-group (with Exocelina miriae-subgroup), a polyphyletic complex of related species with lateral setation on the median lobe. In the light of newly available material, all previously described species of the Exocelina rivulus-group are considered to belong to a single species, Exocelina damantiensis (Balke, 1998), which is now placed into the Exocelina danae-group, and three new synonyms are therefore proposed: Exocelina madangensis (Balke, 2001) syn. n., Exocelina patepensis (Balke, 1998) syn. n., and Exocelina rivulus (Balke, 1998) syn. n. Exocelina tarmluensis (Balke, 1998) syn. n. is a junior synonym of Exocelina danae (Balke, 1998). Redescription of Exocelina atratus (Balfour-Browne, 1939) is provided based on its type material. An identification key to all known species of the group is provided, and important diagnostic characters are illustrated. Data on the species distribution are given, showing that whilst most species are local endemics, Exocelina damantiensis is extremely widely distributed.


Introduction
-habitus oblong-oval (broadest approximately at elytral midlength), with rounded pronotal and elytral sides, body outline continuous; -pronotum short, trapezoidal, with posterior angles not drawn backwards; -coloration brown to piceous, mainly uniform, sometimes with paler head and pronotum and darker elytra; -microreticulation and punctation of dorsal surface very fine to strongly impressed, beetles shiny to matt dorsally; -metacoxae and abdominal ventrites 1-5 (and 6 in males) with thin, almost longitudinal striae/strioles; -pronotum and elytra without striae or strioles; -pronotum with lateral bead; -antennomeres not modified or modified: antennomere 2 distinctly enlarged in male and female; -male protarsomeres 1-3 not expanded laterally; -male protarsomere 4 cylindrical, narrow, with large or small anterolateral hooklike seta; -male protarsomere 5 not modified: long and narrow, without expansion and concavity, ventrally with two rows of short setae or with anterior band and posterior row of relatively long setae; -median lobe of aedeagus with continuous outline in ventral and lateral views; -ventral sclerite of median lobe more or less deeply divided apically; -distal part of median lobe with lateral setae; -paramere with or without notch on dorsal side; -paramere with subdistal setae dense, strong, long; proximal setae similar to subdistal but sparser and thinner, often weakly visible.
Based on analyses of the molecular data (Toussaint et al. 2014, supplementary figs 1-4), we state that the E. danae-group is a polyphyletic complex of the related species, most of which together with the E. broschii-group and E. monae ) build a monophyletic cluster of morphologically diverse species with some general characters: presence of lateral pronotal bead and lateral setation of the median lobe, unmodified paramere, with distinct, dense subdistal setae and inconspicuous proximal setae, and antennomere 2 distinctly enlarged or equal to or larger than antennomere 3.
In the E. danae-group, the Exocelina miriae-subgroup is recognized based on the distinctly enlarged antennomere 2. This subgroup includes three species: Exocelina miriae , Exocelina rufa , and Exocelina tekadu Shaverdo & Balke, sp. n. In former species, antennomere 2 is enlarged in both males and females (less strongly). The females of two latter species are unknown, therefore, we can only assume the modification of the female antennomere 2 in them. This state is also recorded for Exocelina ullrichi , which also has an enlarged antennomere 2 in both sexes. This is an interesting fact, since, in the majority of Exocelina species in New Guinea, males have modified antennomeres, but females do not have such modifications. numerous fine setae situated linearly usually on anterior half of distal part of median lobe; paramere without notch, slightly concave on dorsal side and with dense, strong setae on subdistal part and fine proximal setae ( Fig. 2B-D).
Variability. Specimens from the Eastern Highlands have a shorter apex of the median lobe and more numerous lateral setae situated on almost the whole distal part of the median lobe (Fig. 3).
Diagnosis. Beetle small (TL-H 3.45-3.5 mm); reddish brown; matt, with dense, strong punctation and strongly impressed microreticulation; pronotum with distinct lateral bead; male antennomere 2 distinctly enlarged, antennomeres 3-6 stout (Fig. 24); protarsomere 4 with large, strongly curved anterolateral hook-like setae; male protarsomere 5 ventrally with anterior band of 23 and posterior row of 5 relatively long, thin setae (Fig. 1A); median lobe evenly curved, with slightly curved, elongate and broadly pointed in lateral view, evenly tapering, with broadly rounded apex (slightly truncate on very tip) in ventral view, on both lateral sides with numerous fine setae situated linearly on almost whole distal part of median lobe; paramere without notch, slightly concave on dorsal side and with dense, strong setae on subdistal part and fine proximal setae ( Fig. 1B-D).

Exocelina tekadu
Diagnosis. Beetle medium-sized; brown, with reddish head and pronotum; shiny; male antennomeres modified: antennomere 2 distinctly enlarged, antennomeres 3-6 stout; protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe with slightly curved, broad apex in lateral view and with concave apex in ventral view, on both lateral sides with small bunch of fine distal setae; paramere without notch on dorsal side. The species is similar to E. miriae and E. rufa in the presence of the enlarged male antennomere 2, but differs from them in the shape and setation of the median lobe, as well as in distinctly finer dorsal punctation and microreticulation; from E. rufa also in size and coloration.
Description. Size and shape: Beetle medium-sized (TL-H 3.95 mm, TL 4.5 mm, MW 2.2 mm), with oblong-oval habitus, broadest at elytral middle. Coloration: Head reddish brown, with small darker areas posterior to eyes; pronotum reddish brown, with small brown to dark brown area on disc; elytra dark brown, with narrow reddish sutural lines; head appendages yellowish red, legs reddish, distally darker, especially metathoracic legs (Fig. 26).
Surface sculpture: Head with rather dense punctation (spaces between punctures 1-2 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation or equal for some punctures. Pronotum with much sparser and finer punctation than on head. Elytra with very sparse and fine punctation. Pronotum and elytra with weakly impressed microreticulation, dorsal surface shiny. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal ventrites with distinct microreticulation, strioles, and very fine sparse punctation.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively narrow, slightly convex, with distinct lateral bead and few setae; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 slightly truncate.
Male: Antennomere 2 distinctly enlarged, antennomeres 3-6 stout ( Fig. 26). Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of more than 50 and posterior row of 7 rather long setae (Fig. 4A). Median lobe with slightly curved, broad apex in lateral view and with concave apex in ventral view, on both lateral sides with small number of fine setae situated in a bunch on distal part of median lobe close to apex. Paramere without notch, slightly concave on dorsal side and with dense setae on subdistal part; proximal setae inconspicuous ( Fig. 4B-D). Abdominal ventrite 6 with 7-8 lateral striae on each side.
Female: unknown. Distribution. Papua New Guinea: Morobe Province. The species is known only from the type locality (Fig. 40).
Etymology. The species is named after Tekadu Village. The name is a noun in the nominative singular standing in apposition.

Other species
The species described below do not have modified antennae. ages and legs proximally yellowish red, legs distally darker, reddish brown, especially metathoracic legs (Fig. 29). Teneral specimens paler. Surface sculpture: Head with very dense punctation (spaces between most of punctures equal size of punctures), sparser anteriorly; diameter of most of punctures equal diameter of cells of microreticulation. Pronotum and elytra with sparser and slightly finer punctation than on head. Pronotum and elytra with strongly impressed microreticulation, dorsal surface matt. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles, abdominal ventrites with distinct microreticulation and strioles. Metaventrite medially, metacoxal plates, and abdominal ventrites with sparse but distinct punctation.

Exocelina andakombensis
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, and smooth, with distinct lateral bead and few lateral setae; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 slightly truncate.
Male: Antennae simple. Protarsomere 4 with small (equal to laterally situated large seta), weakly curved anterolateral hook-like seta; small setae around it reduced. Protarsomere 5 ventrally with anterior row of 8 and posterior row of 3 short setae (Fig.  7A). Median lobe with slightly curved, rounded apex in lateral view and with almost truncate apex in ventral view, on both lateral sides with strong, short setae situated almost linearly on a half of distal part of median lobe. Paramere without notch, slightly concave on dorsal side and with dense setae on subdistal part; proximal setae inconspicuous ( Fig. 7B-D). Abdominal ventrite 6 with 6-9 lateral striae on each side.
Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.

Exocelina atrata
Diagnosis. Beetle medium-sized, dark brown, with paler, reddish-brown, head and pronotal sides; dorsal surface with fine punctation and evident microreticulation, shiny; pronotum with distinct lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe broad, with almost parallel sides and broadly rounded apex in ventral view and with slightly curved apex, some short distal setae in lateral view; paramere without notch on dorsal side.
Surface sculpture: Head with dense and coarse punctation (spaces between punctures 1-2 times size of punctures); diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with evident, dense punctation, finer, sparser than on head. Elytra with finer, sparser punctation than on pronotum, punctation fine but distinct. Pronotum and elytra with distinct microreticulation, dorsal surface shiny. Head with microreticulation slightly stronger. Metaventrite, metacoxa, and abdominal ventrites distinctly microreticulate, but with cells of microreticulation larger than on dorsal side. Metacoxal plates with longitudinal strioles and transverse wrinkles; abdominal ventrites with strioles. Ventrum with inconspicuous punctation, more evident on metacoxal plates and two last abdominal ventrites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, smooth anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 truncate apically.
Male: Antenna simple. Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with dense anterior band of ca. 70 relatively long, thin setae and posterior row of 15 similar setae (Fig. 22A). Abdominal ventrite 6 with 4-5 lateral striae on each side. Median lobe broad, with almost parallel sides and slightly concave apex in ventral view and with slightly curved apex, some short distal setae situated in small groups under very fine carinas in lateral view; ventral sclerite of medial lobe as long as median lobe or slightly longer ( Fig. 22B-C). Paramere without notch, slightly concave on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 22D).
Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 rounded apically, without striae.
Variability and notes on species delimitation. Herein, we synonymize with E. damantiensis three species, which were described and treated as representatives of the E. rivulus-group: E. madangensis, E. patepensis, and E. rivulus . The main difference between these species was in the shape of the medial lobe, therefore, this character was carefully studied in all available populations and illustrated (in ventral and lateral views) for almost all of them (Figs 10-16). It has been found that the shape of the median lobe varies both within and among populations. It can be slightly (e.g., Figs 10B, D, 11A, C, F, 12D, E, F, 13C) or strongly (e.g., Figs 10A, 12A-C, H, 13A, B, D) broadened subdistally. Sometimes, the narrower shape might be due to the fact that specimens are teneral (e.g., Fig. 12D) or were treated for SEM (e.g., paratype of E. madangensis, Fig. 12E). The shape can be less and more narrowed apically, the narrower form being characteristic of eastern populations: Simbu, EHL, Madang, and Morobe, but is also found in specimens from Papua, Sandaun, and the Western Province. The less narrowed apically shape is characteristic of specimens from one population in Morobe (Yakop, Fig. 13C), and sometimes both shapes are found in the same population (Tabubil, Western Pr., Fig. 11E, F). The males of the type series of E. patepensis from the Lae-Bulolo region (Morobe) have a median lobe with a more elongate, almost truncate apex (Figs 13D, 16E), but a similar shape can be also observed in some specimens from the other Morobe populations or in some paratypes of E. damantiensis from the Finisterre Range, Madang. A less elongate apex of the median lobe is found in the population from the border region Simbu/EHL (Fig. 15G, H). In short, the shape of the median lobe is not a reliable character to support the earlier recognized species, or to split the present material into several new species or subspecies. The other characters, such as size, coloration, and dorsal punctation, vary little between localities. The beetles are medium-sized, piceous or reddish brown (probably more teneral forms), often with a paler head and pronotal sides, sometimes with reddish sutural lines on the elytra, and are shiny dorsally, with the punctation on the elytra fine, rather distinct or almost invisible. Protarsomere 4 always has a large, thick, strongly curved anterolateral hook-like seta; indication of the "small antero-lateral hook" for E. madangensis in  is probably a mistake.
Thus, the E. rivulus-group is apparently not a complex of several species, but instead a single, very successful polymorphic species E. damantiensis, with the largest geographical range of any New Guinea Exocelina: along the central mountain range from Wandammen Peninsula to Huon Peninsula. Of course, it is not out of the question that further material and study of other aspects (e.g., population genomics) might change this situation.
Distribution and habitats. Indonesia and PNG. It occurs in the central mountain chain and the mountains of Wandammen and Huon Peninsulas (Fig. 39). There, it is one of the most common and numerous species from 450 m to 1900 m. Usually, it is a dominate species in the biotope and co-occurs with many species, some of which are mentioned under "Females of doubtful identity".
Our study of the types of E. tarmluensis revealed no significant difference of this species from E. danae in the external morphology and in the structure of its genitals. Only slight variability in the shape of the apex of the median lobe was noted . Therefore, E. tarmluensis is recognized as a synonym of E. danae.
Distribution. Indonesia: Papua Province: Pegunungan Bintang Regency; PNG: Sandaun Province (Fig. 40). Diagnosis. Beetle medium-sized, dark brown to piceous; dorsal punctation and microreticulation fine; pronotum with lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe slightly broadened and almost rounded distally, with apex weakly concave in ventral view and evenly curved in lateral view, with numerous fine laterodistal setae; paramere without notch on dorsal side; subdistal setae dense, proximal inconspicuous. This species is very similar to E. damantiensis but differs from it in the shape of the median lobe: almost rounded distally in ventral view and evenly tapering in lateral view; its apex not curved in lateral view, as well in less numerous subdistal setae of the paramere. These morphological characters and the fact that this species is phylogenetically quite isolated from E. damantiensis (Toussaint et al. 2014) support its delimitation.
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. 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 distinct ridge, smooth and not rounded anteriorly, 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 ventrite 6 slightly truncate apically.
Male: Antenna simple. Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of ca. 50 and posterior row of 11 relatively long setae (Fig. 21B). Abdominal ventrite 6 with 4 lateral strioles on each side. Median lobe slightly broadened and almost rounded distally, with apex weakly concave in ventral view and evenly tapering in lateral view; on both lateral sides with fine setae situated on distal part of median lobe (Fig. 21B-C). Paramere without notch on dorsal side and with dense setae on subdistal part; proximal setae more numerous but inconspicuous (Fig. 21D).
Distribution. Papua New Guinea: Morobe Province. This species is known only from the type locality area (Fig. 40).
Etymology. The species is named after Garaina Village. The name is a noun in the nominative singular standing in apposition. Diagnosis. Beetle small; piceous, with reddish brown to brown head and pronotum laterally; matt, with strong punctation and microreticulation; male antennae simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe with slightly curved, rounded apex in lateral view and with almost truncate apex in ventral view, on both lateral sides with strong, short setae situated almost linearly on anterior half of distal part of median lobe under fine carina; paramere without notch on dorsal side. The species is very similar to E. andakombensis sp. n. but differs from it in presence of the lateral carina, bordering shorter distal setae, on the median lobe and the large, thick, strongly curved anterolateral hook-like seta of protarsomere 4, as well as longer and much numerous ventral setae of protarsomere 5, see also under diagnosis of E. andakombensis sp. n.
Surface sculpture: as in E. andakombensis sp. n. Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, and smooth, with distinct lateral bead and few lateral setae; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 slightly truncate.
Male: Antennae simple. Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of 19 and posterior row of 8 relatively long setae (Fig. 8A). Median lobe with slightly curved, rounded apex in lateral view and with almost truncate apex in ventral view, on both lateral sides with strong, short setae situated almost linearly on a half of distal part of median lobe under fine carina (Fig. 8B-C). Paramere without notch, slightly concave on dorsal side and with dense setae on subdistal part; proximal setae inconspicuous (Fig. D). Abdominal ventrite 6 with 6-9 lateral striae on each side.
Holotype: TL-H 3.6 mm, TL 3.9 mm, MW 1.9 mm. Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.
Distribution. Papua New Guinea: Morobe Province. The species is known only from the type locality (Fig. 40).

Exocelina kabwumensis
Diagnosis. Beetle small to medium-sized; piceous, with reddish brown to brown head and pronotum laterally; matt, with strong punctation and microreticulation; male antennae simple; protarsomere 4 with weakly curved anterolateral "hook-like" (not modified into a hook) seta, smaller than more laterally situated large seta; median lobe narrow, with almost parallel sides and askew truncate apex in ventral view, with slightly curved apex and very few fine distal setae in lateral view; paramere with small notch on dorsal side. The species is very similar to E. andakombensis sp. n., E. injiensis sp. n., and E. woitapensis sp. n., but differs from them in size, shape of the median lobe, and the presence of only few fine distal setae laterally on the median lobe.
Surface sculpture: As in E. andakombensis sp. n. Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, and smooth, with distinct lateral bead and few lateral setae; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 slightly truncate or broadly rounded.
Male: Antennae simple. Protarsomere 4 with very small, weakly curved anterolateral "hook-like" (not modified into a hook) seta, smaller than more laterally situated large seta. Protarsomere 5 ventrally with anterior band of 27 and posterior row of 6 relatively long, thin setae (Fig. 5A). Median lobe narrow, with almost parallel sides and askew truncate apex in ventral view, with slightly curved, relatively broad apex and very few fine distal setae in lateral view (Figs 5B-C). Paramere with small notch on dorsal side and with dense setae on subdistal part; proximal setae inconspicuous (Fig.  5D). Abdominal ventrite 6 with 8-10 lateral striae on each side.
Holotype: TL-H 3.65 mm, TL 4.0 mm, MW 2.0 mm. Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.
Distribution. Papua New Guinea: Morobe Province. The species is known only from the type locality (Fig. 40).
Etymology. The species is named after Kabwum Village. The name is an adjective in the nominative singular. Diagnosis. Beetle medium-sized, piceous, with paler sides of pronotum; dorsal surface with fine punctation and evident microreticulation, shiny; pronotum with distinct lateral bead; male antennomeres simple; protarsomere 4 with weakly curved anterolateral hook-like seta, smaller than more laterally situated large seta; median lobe evidently broadened in distal part, broadly pointed to apex in ventral view and with slightly curved, rounded apex in lateral view, on both lateral sides with numerous fine setae situated linearly on anterior half of distal part of median lobe under fine carina; paramere without notch on dorsal side. The species is similar to E. posmani sp. n. but differs from it mainly in the structure of the median lobe: apex longer and narrower in lateral view and pointed in ventral view, distal setae not arranged into one area but situated linearly along the lateral margin.
Surface sculpture: Head with relatively dense and coarse punctation (spaces between punctures 1-3 times size of punctures); diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distrib-uted punctation than on head. Elytra with much finer, sparser punctation than on pronotum. Pronotum and elytra with distinct microreticulation, dorsal surface shiny. Head with microreticulation slightly stronger. Metaventrite, metacoxa, and abdominal ventrites distinctly microreticulate. Metacoxal plates with longitudinal strioles and transverse wrinkles; abdominal ventrites with strioles. Ventrum with inconspicuous punctation, more evident on metacoxal plates and two last abdominal ventrites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, not rounded anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 broadly rounded or slightly truncate.
Male: Antenna simple. Protarsomere 4 with very small (smaller than more laterally situated large seta), weakly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of 27 setae and posterior row of 5 short, relative thick setae (Fig.  20A). Abdominal ventrite 6 with 7-10 lateral striae on each side. Median lobe evidently broadened in distal part, braodly pointed to apex in ventral view and with slightly curved, rounded apex in lateral view, on both lateral sides with numerous fine setae situated linearly on anterior half of distal part of median lobe under fine carina ( Fig.  20B-C). Paramere without notch, slightly concave on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 20D).
Holotype: TL-H 4.5 mm, TL 4.9 mm, MW 2.2 mm. Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.
Variability. Elytral punctation varies from inconspicuous to distinct. Distribution. Papua New Guinea: Eastern Highlands and Gulf Provinces. The species is known only from the Marawaka area (Fig. 40).
Etymology. The species is named after the Marawaka area. The name is a noun in the nominative singular standing in apposition. Diagnosis. Beetle medium-sized, piceous, with paler head and sides of pronotum; dorsal surface with fine punctation and evident microreticulation, shiny; pronotum with distinct lateral bead; male antennomeres simple; protarsomere 4 with weakly curved anterolateral hook-like seta, equal to more laterally situated large seta; median lobe only slightly broadened in distal part, with almost parallel sides and slightly concave apex in ventral view, with slightly curved, broad, rounded apex in lateral view, on both lateral sides with numerous fine setae situated not linearly but on large area of anterior half of distal part of median lobe under short fine carina; paramere without notch on dorsal side. The species is similar to E. marawaka sp. n. but differs from it in the structure of the median lobe: apex shorter and broader in lateral view and slightly concave in ventral view, distal setae arranged into one area, not situated linearly. This species was collected together with of E. woitapensis sp. n., which is smaller and matt, with stronger punctation and microreticulation of the dorsal surface.
Surface sculpture: As in E. marawaka sp. n. Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, not rounded anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 broadly rounded.
Male: Antenna simple. Protarsomere 4 with small (equal to more laterally situated large seta), weakly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of 22 setae and posterior row of 5 short setae (Fig. 23A). Abdominal ventrite 6 with 4-7 lateral striae on each side. Median lobe only slightly broadened in distal part, with almost parallel sides and slightly concave apex in ventral view, with slightly curved, broad, rounded apex in lateral view, on both lateral sides with numerous fine setae situated not linearly but on large area of anterior half of distal part of median lobe under short, fine carina ( Fig. 23B-C). Paramere without notch, slightly concave on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 23D).
Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.
Variability. Elytral punctation varies from inconspicuous to distinct. Distribution. Papua New Guinea: Central Province (Fig. 40). Etymology. The species is named for Aloysius Posman. The species name is a noun in the genitive case. Diagnosis. Beetle medium-sized, dark brown, with reddish-brown pronotal sides; dorsal surface with strong punctation and microreticulation, matt; pronotum with distinct lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe slender, with slightly curved, short, broad apex and compact area of fine distal setae in lateral view, with slightly concave apex in ventral view; paramere with very shallow notch on dorsal side. The species is very similar to E. wareaga sp. n. but differs from it in shape of the median lobe: it is more slender, lateral margins apically and subapically not very thick and not bordered with a carina; also the fine distal setae on lateral sides of the median lobe are not situated linearly, but in compact areas.
Surface sculpture: as in E. wareaga sp. n. Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, smooth anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 broadly rounded.
Male: Antenna simple. Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of more than 70 short setae and posterior row of 12 relatively long, thin setae (Fig. 18A). Abdominal ventrite 6 with 4-6 lateral striae on each side. Median lobe slender, with slightly curved, short, broad apex and compact area of fine distal setae in lateral view, with slightly concave apex in ventral view . Paramere with very shallow notch on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 18D).
Etymology. The species is named after Varirata National Park. The name is a noun in the nominative singular standing in apposition.  Wareaga, 760m, 27x2009 9.25.424S 147.31.068E Sagata (PNG227)" (ZSM). Paratypes: Central: 39 males, 46 females with the same label as the holotype (NHMW, ZSM). 7 males, 6 females "Papua New Guinea: Central, Moroka area, Kailaki, 827 m, 26.x.2009, 9.24.134S 147.33 Diagnosis. Beetle medium-sized, dark brown, with paler, reddish-brown, head and pronotum; dorsal surface with fine punctation and evident microreticulation, shiny; pronotum with distinct lateral bead; male antennomeres simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe robust, apicolaterally with thick margins bordered with dorsolateral carina, with slightly curved, broad apex in lateral view and with truncate apex in ventral view, on both lateral sides with numerous fine setae situated linearly on anterior half of distal part of median lobe; paramere with very shallow notch on dorsal side. The species is very similar to E. varirata sp. n. but differs from it in the shape of the median lobe: it is more robust, lateral margins apically and subapically thicker, bordered with a dorsolateral carina; also fine distal setae on lateral sides of the median lobe are situated linearly.
Surface sculpture: Head with relatively dense and coarse punctation (spaces between punctures 1-3 times size of punctures); diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head. Elytra with finer, sparser punctation than on pronotum, punctation very fine but evident. Pronotum and elytra with distinct microreticulation, dorsal surface shiny. Head with microreticulation slightly stronger. Metaventrite, metacoxa, and abdominal ventrites distinctly microreticulate, but with cells of microreticulation larger than on dorsal side. Metacoxal plates with longitudinal strioles and transverse wrinkles; abdominal ventrites with strioles. Ventrum with inconspicuous punctation, more evident on metacoxal plates and two last abdominal ventrites.
Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, smooth anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 slightly truncate.
Male: Antenna simple. Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of more than 70 short setae and posterior row of 13 relatively long, thin setae (Fig. 17A). Abdominal ventrite 6 with 3-5 lateral striae on each side. Median lobe robust, apicolaterally with thick margins bordered with dorsolateral carina, with slightly curved, broad apex in lateral view and with truncate apex in ventral view, on both lateral sides with numerous fine setae situated linearly on anterior half of distal part of median lobe (Fig. 17B-C). Paramere with very shallow notch on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 17D).
Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.
Distribution. Papua New Guinea: Central and National Capital District Provinces (Fig. 40).
Etymology. The species is named after Wareaga village. The name is a noun in the nominative singular standing in apposition. Diagnosis. Beetle medium-sized; piceous, with reddish brown head and pronotum, later often with darker disc; matt, with strong punctation and microreticulation; male antennae simple; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; median lobe relatively broad, with slightly curved, rounded apex in lateral view and with askew truncate apex in ventral view, on both lateral sides with numerous strong setae situated broad-linearly on whole distal part of median lobe; paramere with small notch on dorsal side. The species is very similar to E. kabwumensis sp. n. but differs from it in the larger body size, broader median lobe, and the presence of numerous thick distal setae laterally on the median lobe. It is also similar to E. andakombensis sp. n. and E. injiensis sp. n. but differs from them in the larger body size, shape of the median lobe, and more numerous and more sparsely situated thick distal setae laterally on the median lobe. From E. kabwumensis and E. andakombensis, it also differs in the large, thick, strongly curved anterolateral hook-like seta of protarsomere 4. This species co-occurs with E. posmani sp. n., see under its diagnosis for their morphological differences.
Surface sculpture: As in E. andakombensis sp. n. Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, and smooth, with distinct lateral bead and few lateral setae; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 slightly truncate.
Male: Antennae simple. Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of ca. 60 and posterior row of 16 relatively long, thin setae (Fig. 6A). Median lobe relatively broad, with slightly curved, elongate, rounded apex in lateral view and with askew truncate apex in ventral view, on both lateral sides with numerous strong setae situated broadlinearly on whole distal part of median lobe ( Fig. 6B-C). Paramere with small notch on dorsal side and dense setae on subdistal part; proximal setae inconspicuous (Fig.  6D). Abdominal ventrite 6 with 5-8 lateral striae on each side.
Holotype: TL-H 4 mm, TL 4.5 mm, MW 2.15 mm. Female: Without evident differences in external morphology from males, except for not modified pro-and mesotarsi and abdominal ventrite 6 without striae.
Distribution. Papua New Guinea: Central Province (Fig. 40). Etymology. The species is named after Woitape Village. The name is an adjective in the nominative singular.

Key to species of the Exocelina danae-group
The key is based mostly on male characters. In many cases females cannot be assigned to species due to the 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 on external morphology, therefore, in most cases the male genitalia need to be studied for reliable species identification. Numbers in parentheses refer to the arrangement of the species descriptions above.

Habitats
All species treated here are associated with running water as almost all previously studied New Guinea Exocelina (Shaverdo et al. 2012). Figure 41 shows one of the habitats in the Marawaka area: a mid-montane forest stream with small bays and puddles at its edge, which yielded a large number of these beetles. The following nine species are known from this area: E. marawaka sp. n., E. andakombensis sp. n., E. injiensis sp. n., E. miriae , E. hintelmannae (Shaverdo, Sagata & Balke, 2005)  ) 2 E. miriae , Herzog Range, Wagau A male protarsomeres 4-5 in ventral view B median lobe in ventral view C median lobe in lateral view D paramere in external view.        , setae are not shown 13 median lobe in ventral view, PNG, Morobe A, B Kobau C Yakob, PNG74 D Lae-Bulolo, paratype of E. patepensis  14 median lobe in lateral view, IN A West Papua, Wasior B Papua, Nabire-Ilaga, 96#13 C Papua, Wano, Pap027 D Papua, Bime-Calab, 16, paratype of E. rivulus .   ) 25 E. miriae